This PDF file contains the front matter associated with SPIE Proceedings Volume 10586 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Dissolution of ultrathin exposed EUV photoresist can deviate from the bulk regime due to the modulating influence of the adjacent top and bottom interfaces, which can eventually dominate the behavior of the entire film. Furthermore, use of TMAH 0.26N as aqueous developer for CARs has remained the industry standard without thorough investigation of other possible aqueous bases and concentrations. In this work, we provide a detailed description of the interfacial dissolution behavior of model ultrathin EUV resists in a variety of tetraalkylammonium-based developers, using a representative open source polymer platform. Dissolution kinetics measured using QCM (quartz crystal microbalance) with and without added PAG highlight the convolution of vertical distribution of resist additives with their dissolution inhibition effect throughout the resist film. Results for the local dissolution at the resist-substrate interface using interrupted development and AFM measurements are provided and explained in terms of confinement effects (polymer chain mobility, vacid diffusion) and polymer-substrate interactions. This work can serve as initial guidance to understand the attainable interfacial dissolution modulation afforded by a rational developer selection and a matching EUV resist design.

Extreme UV(EUV) technology must be potential solution for sustainable scaling, and its adoption in high volume manufacturing(HVM) is getting realistic more and more. This technology has a wide capability to mitigate various technical problem in Multi-patterning (LELELE) for via hole patterning with 193-i. It induced local pattern fidelity error such like CDU, CER, Pattern placement error. Exactly, EUV must be desirable scaling-driving tool, however, specific technical issue, named RLS (Resolution-LER-Sensitivity) triangle, obvious remaining issue. In this work, we examined hole patterning sensitizing (Lower dose approach) utilizing hole patterning restoration technique named “CD-Healing” as post-Litho. treatment.

Photosensitized Chemically Amplified ResistTM (PSCARTM) **2.0’s advantages and expectations are reviewed in this paper. Alpha PSCAR in-line UV exposure system (“Litho Enhancer”) was newly installed at imec in a Tokyo Electron Ltd. (TELTM)’s CLEAN TRACKTM LITHIUS ProTM Z connected to an ASML’s NXE:3300. Using the Litho Enhancer, PSCAR 2.0 sensitization preliminary results show that suppression of roughness enhancement may occur while sensitivity is increased. The calibrated PSCAR 2.0 simulator is used for prediction of resist formulation and process optimization. The simulation predicts that resist contrast enhancement could be realized by resist formulation and process optimization with UV flood exposure.

Metal oxide nanomaterials have shown promise for use as EUV resists. Recently, significant efforts have focused on tinoxo clusters that have high absorption coefficient Sn centers and radiation sensitive organic ligands. In our studies, we have investigated a β-Keggin butyl-Sn cluster (β-NaSn₁₃), which is charge-neutral and allows studying radiation induced chemistries without interference from counterions. We have used ambient pressure X-ray photoelectron spectroscopy (APXPS) to investigate the contrast properties of the β-NaSn₁₃ in ultrahigh vacuum (UHV) and in the presence of ambient oxygen. These contrast studies indicate that ambient oxygen reduces the dose requirements for the solubility transition of the β-NaSn₁₃ photoresists. APXPS spectra collected before and after the solubility transition shows that ambient oxygen causes a greater loss of butyl ligands from the samples and the formation of more tin oxide for larger doses, suggesting the presence of reactive oxygen species. APXPS was also used to study processes during the post exposure bake, where we compared the differences in film chemistries in ambient oxygen or in UHV. There were only very small differences in the APXPS spectra before exposure and after exposure and the post exposure bake. However, ambient oxygen resulted in some changes for unexposed regions during the post exposure bake; there was a greater ratio of tin oxide to other oxygen species (alkoxy ligands, hydroxyls) for samples annealed in oxygen. These results have significance for EUV and e-beam lithography processing parameters, as well as implications for cluster design and ligand chemistries.

We have investigated the mechanism of photodecomposition of antimony carboxylate complexes of the type Ph3Sb(O2CR′)2 by means of EUV outgassing in combination with isotopic labelling. A series of photoresists were examined to determine the mechanistic pathways by which volatile photoproducts are generated during EUV exposure. A primary volatile photoproduct from triphenylantimony complexes is benzene. However, the source of hydrogen needed to convert the phenyl groups to benzene (Ph-H) is not obvious. We concluded that the primary source of hydrogen to create benzene is external to the film. Additionally, we have prepared isotopically-labelled versions of Ph₃Sb(O₂CCH(CH₃)₂)₂ in which the hydrogens in the isobutyrate ligand were replaced with 0, 1, 6 and 7 deuteriums, to provide information about the relative reactivity of these protons during EUV exposure as analyzed by mass spectrometry. High reaction selectivity was identified within the carboxylate dictated by hydrogen location relative to the carbonyl for both benzene and phenol generation. Lastly, the results of these studies were used to propose a series of reaction pathways to generate the aforementioned reaction byproducts.

Continued improvement in pattern fidelity and reduction in total edge placement errors are critical to enable yield and scaling in advanced devices. In this work, we discuss patterning optimization in a combined two-layer process, using ArFi self-aligned double patterned line and EUV via process in a 10nm test vehicle. In prior work (1), we showed the composite correction ability for lithography and etch systems in single layer processes. Here, we expand on the optimization and setup to improve the single layer process, improve the line edge roughness, and look at a second layer via process. The sum of all those optimizations is the edge placement. Here, we describe the fidelity of the final multilayer pattern and the process budget for a two-layer line and via process in terms of total edge placement error (EPE) (2). In the line process, control of mechanical interactions in the resist and etch process significantly improve line width and line edge roughness (LWR/LER), with a net improvement in LWR of 30% measured after develop, and 18% measured after etch. Pitchwalk is improved using cross wafer etch and litho cooptimization to less than 1.0nm 3σ. For the via process, we determine the root distribution of EPE resulting from the core placement errors at lithography and etch. Results on final multilayer pattern uniformity, overlay, and edge placement are shown.

When technology node transitions to 14nm and beyond, multi-patterning technique including litho-etch-litho-etch (LELE) and self-aligned double patterning (SADP) with optical lithography is required to achieve device scaling until extreme ultraviolet (EUV) comes into full production. Although LELE and SADP are widely used and well-studied for line-space layers, the challenge of contact layers still remains unknown. In addition, process window (PW) and pattern defects are often characterized with lithography printability only before 7nm. However, when the gate length is pushed to the limitation of immersion lithography, hard mask open etch (HMO) also needs to be studied along with lithography printability to further optimize overall patterning process window (PW). In this paper, we first studied several optical proximity correction (OPC) techniques such as source-mask optimization (SMO) and sub-resolution assist features (SRAF) to improve PW. We then characterized the patterning PW on several patterning defects including single-layer bridging, multi-layer bridging, missing contact, unlanded contact, and extra contact by tuning develop CD (DCD) and HMO CD (MCD). SMO such as illumination source and projection lens wavefront has been extensively used to enlarge depth of focus (DoF). Two different XY polarizations sources were optimized via SMO and were verified on silicon based on overlap process window and mask error enhancement factor (MEEF). Both sources have achieved <90nm lithography PW and <3 MEEF for the selected SRAM and logic designs. The effect of SRAF size on patterning PW were studied by obtaining DoF and exposure latitude (EL) post develop and post HMO. DoF was enlarged by 20nm when increasing SRAF size; however, EL was reduced by 6% post develop and by 2% only post HMO, suggesting patterning PW should be studied at post HMO instead of post develop. When characterizing multi-patterning PW, two types of defects need to be considered: type 1) single-layer bridging and missing contact driven by lithography only; type 2) multi-layer bridging, unlanded contact, and extra pattern driven by both lithography and HMO. Type 1 defects were studied by lithography printability from focus-exposure matrix for different targets (dense/semi-iso/iso) and maximum lithography PW was achieved by adjusting DCD. Type 2 defects were studied by adjusting both DCD and MCD (etch bias). Missing contact was improved by 20x and unlanded contact was improve by 5x when DCD was increased by 8%; however, multi-layer bridging was worsen by 10x, which can be improved by decreasing MCD by 8%. As a result, overall patterning PW can only be obtained by combining lithography PW and HMO optimization.

The interaction of 91.6 eV EUV photons with photoresist – in particular chemically amplified resist (CAR) – is different than exposure at 193 nm and 248 nm wavelengths. The latter is understood well and it is known that photons interact with electrons in the resist’s molecular valence orbitals (for chemically amplified resist (CAR) the photon interacts with the photo acid generator (PAG), which leads to a deprotection reaction on a polymer after a thermal catalytic reaction during a post-exposure-bake.). At EUV however, more steps are involved in the radiolysis process between the absorption of the photon and the final chemical modification. These are related to the generation of primary electrons and their decay to lower energy secondary electrons, and most of this steps are not well understood. In this paper, the reaction products from EUV and low energy electron exposure are examined using Residual Gas Analysis (RGA), which measures and analyzes the outgassing products related to the ongoing reactions. This investigation is applied firstly on a model CAR where details of the resist chemical constituents were known prior to testing. The measurement not only resolved information on the expected acid related reactions from the PAG and protection groups, but also exhibited direct scission reactions of the polymer, where some of them lead to polymerization reactions. Moreover, the measurement quantifies the balance between the different ongoing reactions, which were confirmed by contrast curve measurements. Based on learnings on the model resist, applied the measurement technique to commercial resists, where actual resist chemistry composition is not known. Despite that, it was found that information could be deduced to distinguish between acid related ongoing reactions and direct scission of reaction on the base polymer and quantify their relation. Moreover, different generations of commercial resists based on similar chemistry platform were investigated, which revealed that improvements in printing performance could be explained by PAG reaction yield increase.

The photo-mechanism of EUV exposures in chemically amplified photoresists are much different than that of previous lithographic wavelengths. Electrons generated during EUV exposure are demonstrated to be a source of acid production through a process referred to as electron trapping. Density functional theory modeling indicates that it is energetically favorable for the PAG molecule to decompose if an electron is trapped. Low-energy electrons unlikely to produce holes and secondary electrons generate acid indicating electron-PAG interactions are capable to induce decomposition. Additionally, a more easily reduced PAG (i.e. higher likelihood of trapping an electron) produces a higher acid yield supporting electron trapping as a process of acid production. An acid indicator, Coumarin 6, was used to determine the number of acids generated per absorbed EUV photon. The results of these measurements indicate that electron-PAG interactions are a source of acid production through electron trapping; thus, increasing the number of electron-hole pairs available to induce chemical reactions would improve sensitivity. It is expected that lower band gap materials produce more electron-hole pairs after an absorption event. Subsequently, these measurements show that lower band gap polymers generate higher acid yields.

We characterized the reactivity of a model metal resist for extreme ultraviolet (EUV) lithography by using a midInfrared free electron laser (mid-IR FEL). The evaluated metal resist consisted of a zirconium-oxide core and methacrylic-acid (MAA) ligands. The mid-IR spectra of the metal resist were measured to study photoresponse to FEL irradiation. In the spectra, the metal resist exposed with EUV light showed decreases of peaks of MAAs coordinating a metal core and new peaks have emerged. Mid-IR FEL study suggested that the EUV exposure made ligands of the metal resist more reactive, which are possible pointers increasing the sensitivity of the metal resist.

An in situ resist dissolution analysis of a ZrOx-based metal resist in a typical organic solvent developer [e.g., normal butyl acetate (nBA)] revealed three types of dissolution behaviors: “nano-swelling” at the film surface, “nonuniform dissolution” in the mid-film region, and “resist residue” at the bottom. Attributed to the presence of metal resist film depth inhomogeneities, these dissolution behaviors can impact the EUVL imaging performance of the metal resists. Based on the results obtained, it was also found that developer polarity plays a significant role in obtaining a more uniform or stable dissolution characteristic for metal resists.

For semiconductor device manufacturing, line width roughness (LWR) and defect reduction is one of the most important items to obtain high yield. In this study we described the development of novel high absorption resists for use in extreme ultra violet (EUV) lithography system and its LWR and nano-bridge reduction capability. Herein decomposition rates of photo acid generator (PAG) and several high EUV absorption compounds were studied to clarify inefficient pass on acid generation mechanism. As a result, it is revealed that existence of decomposition pass on high EUV absorption compounds degenerates PAG decomposition efficiency. New high absorption materials were synthesized with taking into account its decomposition durability and its lithographic performance were investigated. 15-20% dose reduction keeping its LWR value and nano-bridge reduction were observed even at lower dose condition compared to non-high absorption platform.

Chemically amplified resists have been used for the fabrication of semiconductor devices. With the miniaturization of circuits, the performance of chemically amplified resists approaches their limit due to the acid diffusion. The development of a novel platform without acid diffusion becomes important. In this study, we proposed a negative-type polymer resist used for extreme ultraviolet (EUV) and electron beam (EB) lithography. The proposed resist utilizes polarity change and radical crosslinking triggered by EUV/EB exposure. Polymers having triarylsulfonium cations and 2,2,2-trisubstitued acetophenone as side chains were designed for realizing the dual insolubilization property. 2,2,2- trisubstitued acetophenone was incorporated for the efficient radical generation on the polymer structure for the crosslinking. An onium salt was incorporated for the efficient use of thermalized electrons for the polarity change and the radical generation of the side chain. In addition, triphenyl-(4-vinyl-phenyl)-stannane (StTPSn) was incorporated into the resist polymer as the EUV/EB absorber to enhance sensitivity. The highly sensitive property of the designed polymers was demonstrated.

Current EUV lithography pushes photoresist thickness reduction to sub-30 nm in order to meet resolution targets and mitigate pattern collapse. In order to maintain the etch budgets in hard mask open, the adhesion layer in between resist and hard mask has to scale accordingly. We have reported a grafted polymer brush adhesion layer used in an ultrathin EUV patterning stack and demonstrated sub-36 nm pitch features with significant improvement over existing adhesion promotion techniques [1]. This paper provides further understanding of this class of materials from a fundamental point of view. We first propose a hypothesis of the adhesion mechanism, and probe key factors that could affect adhesion performance. The grafting kinetics study of polymer brush that contains different functional groups to the substrate shows grafting chemistry, time, and temperature are key factors that affect the printing performance. We then conduct a systematic study to understand printing capability at various pitches for different silicon-based substrates. By comparing the process window, we gain comprehensive understanding of the printing limits and failing modes with this approach. We provide a comparative study of a grafted adhesion layer vs. a conventional spin on BARC type material, including defectivity. Pattern transfer to hard mask with varied etch chemistry is conducted to understand the performance of polymer brush during etch.

Currently, there are many developments in the field of advanced lithography that are helping to move it towards increased HVM feasibility^1,2,3,4. Targeted improvements in hardware design for advanced lithography are of interest to our group specifically for HVM metrics such as LWR improvement, dose reduction processes, and defect density reduction. In this work we are building on our experience to improve LWR in an advanced lithographic process by employing novel hardware solutions on our SCREEN DUO coat develop track system⁵ . Our approach is to implement post-litho annealing to improve resist line roughness. Although it is preferable to achieve such improvements post-etch process we feel, as many do, that post-patterning improvements are a precursor to improvements after etching⁶ . We hereby present our work utilizing the SCREEN DUO coat develop track system to improve aggressive dense L/S patterns.

Extreme ultraviolet (EUV) lithography is expected to replace current photolithographic methods because of improved resolution. The atomic photon absorption cross section is a central factor that determines the optimal elements around which to base photoresist chemistry, and tin is a strong absorber for EUV photons (~92 eV). β-NaSn₁₃ ([NaO₄(BuSn)₁₂(OH)₃(O)₉(OCH₃)₁₂(Sn(H₂O)₂)]), one of the organo-tin oxo compounds is being studied in this paper using helium ion beam lithography (HIBL) to demonstrate the patterning performance. High aspect ratio (15:1) and dense line patterns (20 nm half pitch) have been achieved with no defects. Thinner films yielded even smaller feature sizes (linewidths of ~ 10 nm). Thinner films require higher dose to get continuous and solid line patterns presumably due to fewer molecules available for condensation. Studies on various substrates indicate that the high Z substrates can help improve the pattern performance at low doses.

A trilayer stack of spin-on-carbon (SOC), silicon anti-reflective coating (SiARC) and photoresist (PR) is often used to enable high resolution implant layers for integrated circuit manufacturing. Damage to substrates from SiARC removal using dry etching or aqueous hydrogen fluoride has increased the demand for innovative SiARC materials for implant lithography process. Wet strippable SiARCs (WS-SiARCs) capable of stripping under mild conditions such as SC1 (ammonium hydroxide/hydrogen peroxide/water) while maintaining key performance metrics of standard SiARCs is highly desirable. Minimizing the formation of Si-O-Si linkages by introducing organic crosslink sites was effective to impart SC1 solubility particularly after O2 dry etching. Incorporation of acidic groups onto the crosslinking site further improved SC1 solubility. A new siloxane polymer architecture that has SC1 active functionality in the polymer backbone was developed to further enhance SC1 solubility. A new SiARC formulation based on the new siloxane polymer achieved equivalent lithographic performances to a classic SiARC and SC1 strip rate >240Å/min under a relatively low concentration SC1 condition such as ammonium hydroxide/hydrogen peroxide/water=1/1/40.

Hemicellulose spin on carbon (SOC) material was newly developed for hardmask layer. For next generation lithography, high etching selectivity is strongly required. However, there is an issue of a balance of cost and etching selectivity in conventional process. Hemicellulose spin on carbon material is able to overcome this issue by virtue of its chemical structure and newly-developed reactive hemicellulose hardening (R2H). R2H means that hemicellulose unit is selectively hardened by chemical reaction. In this study, deep L/S and hole patterns were fabricated by using hemicellulose SOC with R2H and its dry etching selectivity was 26. Additionally, compatibility with EUV lithography was confirmed. Favorable pattern made of resist for EUV lithography was obtained on Hemicellulose SOC and successfully transferred into hemicellulose SOC.

Irresistible Materials has previously introduced the HM340 series of fullerene based spin-on carbon, and reported on material characterization, including very high carbon content and high thermal stability. The materials have a low Ohnishi number providing high etch durability and the low hydrogen level allows for high-resolution etching without wiggling. Here we present further investigation of the spin-on-carbon, and demonstrate the flexibility of the platform. Film carbon content can be easily varied from as high as 95% (suitable for high durability etches) to as low as 80% (for instance to use as a sacrificial etch material). We present characterisation of the optical properties of the materials, and process and formulation developments. Work to vary the curing temperature between 200 and 300°C, and to reduce cure times to 90 seconds or less has been successfully undertaken. Alternative casting solvents have been investigated and work to achieve spin coatable film thickness ranges from less than 50 nm to significantly more than 500nm is described. and spin-coatable film thickness ranges from less than 50 nm to significantly more than 500nm are described. Results from initial planarisation trials are presented together with initial results from on-going work on spin-on carbon formulations that exceed 95% carbon content.

We have developed block co-polymers (BCPs) in which one of the blocks incorporates silicon and the other does not [1]. These materials provide access to BCPs with high Flory-Huggins interaction parameters (χ) and dry etch selectivity under reactive ion etching (RIE) conditions to provide Sub-20 nm patterns [2]. Recently we have investigated a hybrid chemo/grapho-epitaxy process that provides 20 nm and 10 nm full pitch patterning and we have transferred these patterns into useful substrates. This hybrid process produced 20 nm DSA with fewer defects with this material than the conventional chemo-epitaxial process. Cross-sectional scanning transmission electron microscopy (STEM) with electron energy loss spectroscopy (EELS) confirmed that the BCP features span the entire film thickness on hybrid process wafers [3]. We have now succeeded in demonstrating DSA with poly(4-methoxystyrene-block-4-trimethylsilylstyrene) (PMOST-b-PTMSS) aligned by guidelines comprised of cross linked poly(2-vinylpyridine) (Figure a). The process was demonstrated by cross-section analysis to produce features that span the entire BCP film thickness and the introduction of nitrogen into the guide line provides new evidence for the nature of the interaction between the guide lines and the BCP(Figure b). We have also reported the DSA and pattern transfer of poly(5-vinyl-1,3-benzodioxole-block-pentamethyldisilylstyrene) (PVBD-b-PDSS) at 10 nm full pitch. However, in this case, the DSA involved a trade-off between perpendicularity and dislocation defects [4]. Improved brush materials that selectively graft to an etched Cr surface rather than etched imprint resist provide oriented and aligned 5 nm line-and-space patterns that cleanly traverse the full film thickness thickness (Figure c). 1. Bates C. M., et al. Science (2012), 338 (6108), 775. 2. Azarnouchea, L., et al. J. Vac. Sci. Technol. B (2016) 34 (6), 061602/1-061602/10. 3. Blachut, G., et al. Chem. Mater (2016), 28 (24), 8951-8961. 4. Lane A. P., et al. ACS Nano (2017), 11 (8), 7656-i7665.

Self-aligned strategies are required because today’s feature sizes are beyond the resolution limit of the exposure tools. One self-aligned strategy is Directed Self-Assembly (DSA), where block copolymers (BCP) are thermodynamically driven to self-align with a lithographically defined template with chemical contrast and/or topography. Traditionally, DSA has harnessed polymer – polymer interactions to direct the assembly of BCP. A common implementation of this traditional process utilizes a binary chemical pattern which consists of a preferential homopolymer guide stripe and a non-preferential random copolymer background brush. This preferentiality is well understood by comparing the surface energies of the chemical patterns with those of the blocks of the BCP. The random copolymer naturally has a surface energy between the two blocks and is non-preferential; whereas the homopolymer surface energy matches that of one of the blocks and is therefore preferential. This technique requires the patterning of an additional polymer layer which will not be present in the final device, and is used only for directing the assembly. In spite of this, DSA is a promising technique for patterning due to its inherent ability for CD rectification and pitch multiplication. These inherent benefits are due to the complex thermodynamic process which underlies DSA which drives BCP to form only a given CD and Pitch. It would be particularly advantageous to also encode existing structures into thermodynamic information, then thermodynamics would cause BCP to self-align to these existing structures rectifying placement error. These existing features could be cut masks which are required in order to fabricate devices from line and space arrays. This information could also enforce alignment to active metal features. Here we show a new technique, by which metal – polymer interactions can be used in place of polymer – polymer interactions. These metal – polymer interactions, which cannot be adequately described by conventional surface energy comparisons, allow for a true self-aligned process. We begin by classifying process relevant metals including gold, aluminum, copper, tungsten and cobalt based upon their thermodynamic interactions with PS-b-MMA. We then created guide patterns using metal and dielectric line space arrays. These patterns when combined with DSA allow for lines and space patterns to be self-aligned to any exposed metal features and reduce process constraints on exposure tools. The BCP was thermodynamically driven to snap to the metal which could be a cut mask or could be an active interconnect. These BCP line and space patterns can then be transferred into the underlying substrate to produce sparse arrays of lines and spaces aligned with the underlying metal. Our process can also be used to align line and space patterns to metal layers during back end of the line processing. A similar process could also be used to guide contact hole shrink to correct for placement error in the initial lithographic template.

We investigate the fabrication of sub-20 nm pillars by DSA lithography using PS-cylinder-forming PS-b-PMMA block copolymer (BCP). The approach is based on the removal of PMMA-matrix by either dry or wet etching to form PS pillars which act as a soft etching mask that can be further transferred to an intermediate hard one and then to the substrate. The process conditions of BCP self-assembly were optimized in terms of annealing temperature, brush layer composition and film thickness. It was demonstrated that PS/PMMA volume fractions of 50/50 in the PS-r-PMMA brush layer is the most adapted to obtain standing PS cylinders. Top-down SEM images showed a hexagonal array of PS cylinders in a PMMA matrix with a natural period of 33.5 nm (determined by Fast Fourier Transform FFT method) and CD around 15 nm. Both wet and dry etching strategies for PMMA removal were discussed. It was shown that UV exposure followed by organic solvent development is necessary to decrease pattern collapsing during PMMA removal step which is the most critical issue for pillar fabrication. PMMA removal by dry etching was shown to completely avoid this pattern collapsing. Finally, pillars etching transfer to typical organic Si containing antireflective coating and spin on carbon (SiARC/SOC) hard mask and then to the silicon substrate was demonstrated. Si pillars of 15 nm CD and 70 nm height were obtained with a straight profile shape.

This paper presents a design and technology co-optimization (DTCO) study of metal cut formation in the sub-20-nmregime. We propose to form the cuts by applying grapho-epitaxial directed self-assembly. The construction of a DTCO flow is explained and results of a process variation analysis are presented. We examined two different DSA models and evaluated their performance and speed tradeoff. The applicability of each model type in DTCO is discussed and categorized.

Directed self-assembly (DSA) of block copolymers (BCPs) is a lithographic technique that is expected to be mutually complimentary with ArF immersion lithography, EUV lithography, electron beam direct writing, or nanoimprint for sub-15 nm line patterning and sub-20 nm contact hole patterning. Defect mitigation is the primary challenge behind the use of DSA lithography in practical applications in advanced semiconductor device manufacturing. Therefore, resolve this issue, defect dynamics needs to be clarified using in-situ measurements of self-assembling processes of BCPs in conjunction with modeling approaches. In this work, the evolution of a surface morphology in self-assembling processes of BCPs during annealing was investigated using in-situ atomic force microscope (AFM).5 A JPK NanoWizard ULTRA Speed AFM (JPK Instruments AG) under AC mode (lock-in phase signal image) was employed to carry out in-situ measurements of self-assembling of symmetrical polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) thin films with a thickness of 40 nm, and a domain spacing 30 nm domain spacing (L0) of 30 nm on a 5 nm thick neutral layer (PS-r-PMMA) during the thermal annealing process starting from a disordered as-cast state. The COOrdinated Line epitaxy (COOL) process was applied to provide DSA line multiplication patterns as hybrid guide patterns which act as chemical and physical epitaxy process. The in-situ observation approach of the surface morphology during micro-phase separation process revealed the defect generation and rectification processes in DSA thin films. A combination of the time development data in the in-situ AFM and grazing-incidence small-angle X-ray scattering (GI-SAXS) will also be discussed to develop a kinetic modeling for predicting dynamical changes in the three-dimensional nanostructures.

Directed self-assembly (DSA) of block copolymer (BCP) thin films has been extensively researched as an alternative lithographic technology to enhance the resolution beyond the limitation of current lithography techniques.[1] One of the most critical factors need to be addressed for DSA process to be accepted at high volume manufacturing (HVM) is defect density of DSA pattern.[2] The defects of thermodynamically driven DSA process, such as the dislocation defects in LiNe flow, are known as kinetically trapped metastable structures.[3] Therefore, a key to eliminate those defects is to find out the effective kinetic pathway of assembly that enables BCP to reach to defect-free structure more easily. In addition to defect annihilation, easy pathway will also allow faster assembly, consequently reducing the cost of ownership of DSA process. The obvious approach for faster assembly in DSA process is to increase annealing temperature. In this study, we address the impact of annealing temperature on DSA process. First, increasing annealing temperature makes the free surface of a PS-b-PMMA film more PMMA preferential. Because of altered boundary condition at the top surface, more careful optimization of backfilling brush was required to maintain preferred orientation of BCP films. Second, the dimension of BCP is also affected by annealing temperature. Temperature dependency of BCP dimension was quantitatively investigated by CD-SEM and DSA-APPS Offline CD Measurement Software (Figure 1a). Based on the measured values, the dimension of chemical pattern is accordingly modified to achieve aligned DSA pattern (Figure 1b). We anticipate our finding from this study can be generally applied for other BCP systems. [1] Ruiz, Ricardo, Huiman Kang, François A. Detcheverry, Elizabeth Dobisz, Dan S. Kercher, Thomas R. Albrecht, Juan J. de Pablo, and Paul F. Nealey. "Density multiplication and improved lithography by directed block copolymer assembly." Science 321, no. 5891 (2008): 936-939. [2] Gronheid, Roel, Paulina Rincon Delgadillo, Hari Pathangi, Dieter Van den Heuvel, Doni Parnell, Boon Teik Chan, Yu-Tsung Lee et al. "Defect reduction and defect stability in IMEC's 14nm half-pitch chemo-epitaxy DSA flow." In SPIE Advanced Lithography, pp. 904905-904905. International Society for Optics and Photonics, 2014. [3] Hur, Su-Mi, Vikram Thapar, Abelardo Ramírez-Hernández, Gurdaman Khaira, Tamar Segal-Peretz, Paulina A. Rincon-Delgadillo, Weihua Li, Marcus Müller, Paul F. Nealey, and Juan J. de Pablo. "Molecular pathways for defect annihilation in directed self-assembly." Proceedings of the National Academy of Sciences 112, no. 46 (2015): 14144-14149.

In this paper we will describe a self-consistent field theory simulation study on bridge defects in lamellae-forming diblock copolymers. Because the bridge defects are buried three-dimensional defects formed in the diblock copolymer film, it is difficult to observe and determine what causes them. To determine the cause of the bridge defects effectively, self-consistent field theory simulations were used. By reproducing structural characteristics of the bridge defects in the simulation, the cause of the bridge defects were clarified. Finally, we discussed ways to prevent the bridge defects.

Directed self-assembly (DSA) of block copolymers (BCPs) is one of the most promising techniques to tackle the everincreasing demand for sub-lithographic features in semiconductor industries. BCPs with high Flory Huggins parameter (χ) are of particular interest due to their ability to self-assemble at the length scale in sub-10 nm regime. However, such high-χ BCPs typically have imbalanced surface energies between respective blocks, making it a challenge to achieve desired perpendicular orientation. To address this challenge, we mixed a polymeric additive with poly(2-vinylpyridine)- block-polystyrene-block-poly(2-vinylpyridine) (P2VP-b-PS-b-P2VP) and successfully achieved perpendicular orientation control of the triblock copolymer. The polymeric additive has lower surface energy than both PS and P2VP blocks, and it selectively interacts with high surface energy P2VP blocks via hydrogen bonding. As a result, the surface energies of PS and P2VP blocks are balanced and perpendicular orientation forms upon thermal annealing. Using this approach, we demonstrate 5X density multiplication DSA with a half pitch of 8.5 nm via chemo-epitaxy. This material system is also amenable to sequential infiltration synthesis (SIS) without the need to remove the additive, revealing its pattern transfer potential. We believe that this integration-friendly DSA approach using simple thermal annealing holds the promise of bringing high-χ BCPs to advanced nanopatterning applications.

A variety of advanced DSA materials have been developed to offer the ease of fabrication and precise control of DSA processes, especially to minimize the number of processing steps and material depositions needed in the DSA implementation. Exemplary materials include spin-on hardmask neutral layer (HM-NL) materials, crosslinkable guiding polymers materials (X-mat), and block copolymers (BCPs) with respective unique combinations of multiple functionalities, e.g., HM-NL materials having etch resistance capability, reflectance control, and non-preferential surface energy to BCP blocks; BCPs with solubility in orthogonal solvents to photoresist, low thermal annealing temperatures required, and no need for top-coat or solvent annealing to get perpendicular orientation. Empowered by these materials, both conventional graphoepitaxy and chemoepitaxy DSA processes can be simplified and enhanced with more potential. For instance, simplified graphoepitaxy DSA by using positive-tone development (PTD) photoresist patterns has been successfully demonstrated. This simplified graphoepitaxy DSA has also led to a facile approach to generate chemoepitaxy guiding patterns.

Densely patterned contact holes form a key component of integrated circuits, but there are significant challenges to patterning holes with a sub 10-nm radius. The directed self-assembly (DSA) of block copolymers offers a potential solution, where a larger hole is initially patterned and a cylinder forming block copolymer (BCP) is assembled inside. The radius of the inner BCP cylinder can now be used to template the hole radius. It can be particularly challenging to characterize the internal structure of the DSA patterned contact hole, particularly for features such as the residual layer, which may adversely impact the etching process. The high aspect ratio of these features makes top-down characterization nearly impossible, forcing the use of challenging cross-section based approaches. Critical Dimension small angle X-ray scattering (CDSAXS) offers the possibility of characterizing the internal structure of DSA patterned contact holes. CDSAXS is a variable angle scattering technique which combines measurements from different sample angles to reconstruct the three-dimensional structure of the sample. In this case the scattering yields a two-dimensional pattern, where the off-axis peaks contain additional information about the structure. A model based inverse analysis is then used to fit the scattering and evaluate the structure of the measured target. Contact holes were prepared with a variety of radii and surface treatments in order to evaluate which conditions resulted in optimal assembly of the BCP inside the template. The results demonstrate a correlation between hole radius, surface treatment and residual layer thickness.

1. INTRODUCTION Directed self-assembly (DSA) lithography is one of the promising next generation lithography. There are mainly 2 requirements for next generation lithography. One is smaller size lithography for logic and DRAM etc.. Another is 3D lithography for 3D semiconductor devices. Regarding DSA lithography, wide-range DSA to expand applicable patterning size was studied. However, there are not well known a potential of 3D lithography; deep pattern of directed self-assembly and deep RIE on Si devices. This paper describes xylan high-chi block copolymer and its wider range of 3D patterning size. 2. EXPERIMENTAL RESULTS AND DISCUSSION A structure model of xylan block copolymer for wide-range DSA lithography is proposed. It is composed of A and B part in hydrophobic part and C and D part in hydrophilic part. Part D has xylan structure. The xylan block copolymers were synthesized and dissolved in PGMEA. Metal contamination was removed. Then, they were spin-coated on a substrate with guide pattern, annealed and carried out dry development using RIE on 300 mm wafer. Directed self-assembly patterns were evaluated by SEM. In our experimental results, half pitch 8.3 nm of L/S pattern and CD 51 nm of hexagonal hole pattern were obtained. According to these results, xylan block copolymer is suitable for wide-range DSA. Spin coated thickness of xylan block copolymer were evaluated. From 50 nm to 1.3 μm of thickness was realized and micro phase separation was confirmed. These results suggest xylan block copolymer has a possibility of wider thickness range of micro-phase separation. Si deep RIE of xylan block copolymer was carried out. Silicon depth was 300 nm. It seems that xylan block copolymer is suitable for 3D semiconductor lithography. 3. SUMMARY It was confirmed xylan block copolymer is suitable for 3D patterning size on directed self-assembly lithography. It has a big potential for wider application of not only 2D but also 3D semiconductor devices.

Lamellar CD-SEM image analysis is one of the key step for the development of new polymer formulations. We present in this paper a new approach for the analysis of lamellar CD-SEM that can be extended to any type of other pattern (contact…) with a machine learning approach. We will also focus on the roughness analysis and specifically the Line Edge Roughness (LER) and Power Spectral Density (PSD) with a robust estimation that takes into account curvature of the line. The last part is dedicated to the introduction of a process optimisation technique using machine learning to optimize process parameters from a first design of experiment.

Incorporated in relevant design of guiding templates, DSA (Direct Self Assembly) patterning offers a cost-effective manufacturing method to support pattern shrink for advanced technology nodes. The physical characteristics of the BCP moieties and the self-assembly process, pose unique 3D metrology challenges. Pattern fidelity issues of DSA caused by dislocations, forms residual later that can impact pattern fidelity after Etch. Addressing this challenge can assist the R&D groups to monitor material and process quality to meet patterning specifications. In this paper, we highlight the usage of BSE (Back Scattered Electron) metrology as an innovative approach to characterize the DSA process. Experimental data demonstrate the possibility to characterize the polymer residual layer quality and even assess its thickness for the pattern etch transfer. The quality of the information brought by the BSE imaging make it a must-have to quantify the bottom opening for processed of DSA techniques of pitch multiplication and shrink, from which are not visible with conventional SEM images.

Multi-patterning processes such as self-aligned double patterning (SADP) and self-aligned quadruple patterning (SAQP) present new challenges to the semiconductor device manufacturing such as increased relative cost to previous nodes, longer cycle times, and increased (local) edge placement error between grid and cut/block layers. As the scaling requirements continue, the factors driving both EPE and electrical yield such as overlay, critical dimension control (CDU) and stochastics (LCDU) become greater concerns to multi-patterning. In addition to lithographic process variations, the unit processes such as plasma/vapor etch, deposition, wet/cleans can contributes additional variation in spacer/mandrel profiles leading to poor CDU control and ultimately within-wafer pitch walking. In this paper, we outline alternative SAQP integration schemes to improve the feature profile of both mandrel and spacer to minimize process variability. This patterning scheme designated as fly-cut SAQP introduces new concepts such top spacer removal by chemical-mechanical planarization, mandrel foot mitigation layers, multi-layered mandrel for accurate polish end-point and void-free gap fill to realize high fidelity transfer to the underlying hardmask. Finally, we will demonstrate the effectiveness for this new integration scheme as a candidate for multi-color/self-aligned block (SAB) and highlight the additional benefits of using such an approach.

In this paper, we demonstrate photosensitive polyimide (PSPI) profile optimization to effectively reduce stress concentrations and enable PSPI as protection package-induced stress. Through detailed package simulation, we demonstrate ~45% reduction in stress as the sidewall angle (SWA) of PSPI is increased from 45 to 80 degrees in Cu pillar package types. Through modulation of coating and develop multi-step baking temperature and time, as well as dose energy and post litho surface treatments, we demonstrate a method for reliably obtaining PSPI sidewall angle >75 degree. Additionally, we experimentally validate the simulation findings that PSPI sidewall angle impacts chip package interaction (CPI). Finally, we conclude this paper with PSPI material and tool qualification requirements for future technology node based on current challenges.

Laser ablation of poly(4-hydroxystyrene) (PHOST) film was studied using mid-Infrared free-electron laser (mid-IR FEL), of which irradiation wavelength was tuned to the vibrational absorption peaks of PHOST in mid-IR spectral region. A PHOST film was ablated by mid-IR FEL light to produce a clear hole in a PHOST film which suggested the photochemical ablation. As the threshold energy for silicon ablation was larger than that of PHOST, it was possible to ablate a PHOST film without any damage to a silicon substrate. The ablation threshold-energy ratio for PHOST to silicon was less than 0.2 and depended on the mid-FEL wavelength. The ablation threshold for a PHOST film depended also on the film thickness. The highly efficient ablation by mid-IR FEL was found to be due to the vibrational excitations of C-O stretching and C-O-H bending of PHOST.

Driven by IoT, Industry 4.0, and social media the amount of data to be transferred is tremendously increasing, pushing the need for energy-efficient device concepts for a vast variety of products such as photonic integrated circuits or sensors. Low energy data transfer can be achieved, for example, by replacing part of the electronic circuitry by optical data lines in chip-level packaging, or by introducing optical elements such as specially designed microlenses into semiconductor laser packaging. This also allows to drastically reduce footprints of systems, and – at the same time – to increase functionality. On the other hand, a significant demand is seen in providing lower cost and scalable manufacturing processes with technologies which provide highest flexibility. High Precision 3D Printing as novel emerging fabrication technology is a promising tool for optical packaging. It enables to reduce the necessary process steps for packaging to only three to five, independently of the packaging task. This is enabled by a novel and versatile packaging concept where the chips and the dies are already mounted prior to the fabrication of optically functional elements such as optical interconnects or microoptics to couple, for example chip-to-chip or dies to fiber, with passive alignment only. Flexible exposure strategies using High Precision 3D Printing provide both, scalability and high throughput with fabrication times from seconds for optical waveguides and single microlenses to only a few minutes for more complex lens systems. The impact of the fabrication strategy will be discussed with respect to the performance of the optical devices.

In this work, an evaluation of various ASL processes for 200 mm wafer scale in the HERCULES® NIL equipment platform available at the CEA-Leti through the INSPIRE program is reported. The surface and adherence energies were correlated to the AFM and defectivity results in order to select the most promising ASL process for high resolution etch mask applications. The ASL performances of the selected process were evaluated by multiple working stamp fabrication using unpatterned and patterned masters though defectivity monitoring on optical based-inspection tools. Optical and SEM defect reviews were systematically performed. Multiple working stamps fabrication without degradation of the master defectivity was witnessed. This evaluation enabled to benchmark several ASL solutions based on the grafted technology develop by ARKEMA in order to reduce and optimize the soft stamp defectivity prior to its replication and therefore considerably reduce the final imprint defectivity for the Smart NIL process.

Negative tone development is being employed widely because of its superior resolution. Pall is developing filtration products specially targeted for these high resolution applications. High particle retention and low extractables are key aspects of filtration products known to improve on-wafer defectivity. In the current study, we have found that filtration efficiency of the various filter types towards palladium-heptylamine nanoparticles correlates strongly to actual particle removal determined by on-wafer inspection metrology. Furthermore, using the afore mentioned nanoparticle testing metrology, high retention membranes with low extractables were selected. Particle challenge testing is much simpler than on-wafer defectivity inspection and enables faster and effective filtration membrane selection. Based on these results, the selected filtration membrane is expected to perform effective real particle removal in negative tone developer.

Defect source reduction in leading-edge iArF resists is a critical requirement to improve device performance and overall yield in lithography manufacturing processes. It is believed that some polar polymers can aggregate and be responsible for single or multiple micro-bridge defects. Further investigation into the formation of these defects is needed. We have previously presented the effective removal of gel-like polymers using nylon media ^[1]. However, as the industry is moving to smaller feature sizes, there is a need to further improve the defect removal efficiency. In this paper, a filter, comprised of a novel membrane called Azora with unique morphology and high flow performance is introduced. This new filter shows better on-wafer in an advanced ArF solution than conventional Nylon and UPE media. In addition, it shows improved stability during chemical storage. Results and possible retention mechanisms are discussed.

Metal ions in photoresists and solvents pose an ever greater contamination problem in photolithography’s advanced applications. The reduction of metal contaminants is critical in the entire photochemical supply chain. In this paper we demonstrate that two novel membrane purifiers dramatically reduced the metal contents in a range of organic solvents. These solvents are used for photoresist manufacturing and for wafer surface and dispense line rinse in track tools. The impact of flow rate and metal concentrations in the feed on the metal removal efficiency of the purifiers is presented. Furthermore, a study to determine the dominant mechanism of metal reduction in solvents is proposed.

Airborne molecular contaminants continue to pose cost of ownership challenges in photolithography. Recent advances in understanding siloxane removal have led to the development of an innovative filtration configuration utilizing new media that works in concert to increase overall filter life for acids, bases and silicon containing organic contaminants. This paper examines accelerated testing results, for these state-of-the-art filtration assemblies versus legacy products, to demonstrate improved system performance. The state-of-the-art filtration assemblies have been evaluated in production semiconductor fabs and have shown favorable performance.

Directed self-assembly (DSA) of block copolymers offers opportunities for resolution enhancement of existing patterning by pitch splitting, contact hole (CH) shrinks or, improvement of pattern profile or patterning window.^1-2 By co-optimization of guiding pattern geometry, guiding pattern profile, block copolymer formulation, pattern transfer steps, the after-etch DSA patterns meet target pitch ratio. This DSA assessment shows combination of DSA and single iArF-patterning has potential to meet the specific CD dimension and pitch requirement of a conventional patterns that requires double-patterning.

In recent years, high-χ block copolymers (BCPs) have been reported to achieve sub-5 nm resolution. These BCPs always require long annealing time at high annealing temperature, which may limit their implementation into semiconductor process. Since hot baking time in conventional semiconductor process is normally less than 3 minutes, how to shorter the thermal annealing time at lower temperature becomes a new topic for the sub-5 nm high-χ BCPs. In this manuscript, various fluoro-containing BCPs are synthesized by living anionic polymerization or atom transfer radical polymerization. The best BCP formed thermal equilibrium sub-5 nm nano domains after mere 1 min annealing at temperature lower than 100 °C, which is the fastest thermal annealing process reported so far. BCPs with various morphology and domain size are obtained by precise control of both the length and the molar ratio of the two blocks. The resulted smallest half-pitch of the BCPs are less than 5 nm in lamella and hexagonal morphologies. Linear and starshaped BCPs containing PMMA and fluoro-block are also synthesized, which also shows best phase separation into ca. 6 nm half-pitch, however, the annealing time is 1 hour at 180 °C.

For self-aligned multiple patterning, higher etch selectivity between mandrel and spacer is desired to lessen roughness, and thereby prevent pitch walk. We selected dual carbon layers as mandrels and silicon oxide films as spacers for a new self-aligned quadruple patterning process since they potentially provide infinite etch selectivity. We gained insolubility and etch selectivity between two carbon layers by infiltrating trimethylsilyldimethylamine into one of the carbon layers under the ambient atmosphere. Significantly, neither necking nor recess were observed when the spin-on-glass antireflective coating was removed. Thus, a SAQP scheme was developed and successfully demonstrated a sub15-nm halfpitch pattern. Additionally, this scheme improves affordability since all the processes can be performed in the ambient pressure within a coater module.

Using an electron beam, thin polymeric films loaded with metal nanoparticles of silver were prepared by a one-step irradiation-induced reduction of the metal ions embedded in the polymer. The metal nanoparticles were observed by either optical absorption or microscopy. The mechanism of the reduction of metal ions and of the polymer crosslinking were deduced from the average absorbance measurements. In view of realizing specific patterns of high resolution using the electron beam, electron beam produces 200 nm wide lines that can be separated by unexposed spaces of adjustable width, where precursors were dissolved. The resolution of the electron beam has been exploited to demonstrate the achievement of nanopatterning on polymer films using a direct-writing process. This method supplies interesting applications such as masks, replicas, or imprint molds of improved density and contrast.

It has been widely known that photoresist (PR) will shrink after ion implantation, which contribute additional side effect on the PR edge placement error and PR effective thickness to against next implantation step, and such effect cannot be ignored with the device size shrinkage. KrF process is still the mainstream patterning solution for advanced logic implantation process. And there are two main category KrF resists: Low activation energy (Ea) Resist and High Ea Resist, which show different shrinkage behaviors, but the inside mechanism has not been discussed clearly so far. In this work, we studied the shrinkage behavior of two kinds of KrF resists (Low Ea Resist and High Ea Resist) under different exposure dose and under different implantation condition (acceleration voltage, dosage, and species). Resist shrinkage percentage and its dependence on time at room temperature are the focus of this study since multi-step implantation is widely used for device tuning purpose. It is observed that high Ea resist shrinks instantly after implantation and change little with time, while low Ea resist not only shrinks at the beginning but also shrinks continually with time at room temperature. The low Ea resist irradiated with ion implantation may undergo a two-step process: 1) polymer crosslinking and chain scission by bombardment of high energy ions; 2) deprotection by acid generated during implantation. We compared the shrinkage behavior with just exposure with different energy and just implantation with different voltage/dosage/species and observed some similar shrinkage trend, which may indicate similar mechanisms, however there still exist different contributions.

In the semiconductor manufacturing industry, photoresist materials are used for transferring an image to one or more underlying layers. To increase the integration density of semiconductor devices and reduce cost of ownership, continuous development efforts towards advanced lithography processes, such as multiple patterning methods, have been devoted to reduce critical dimension. Multiple patterning processes, however, often encounter challenges to obtain an appreciable process window due to the poor aerial image contrast at the defocus region, not to mention the complexity in process and high cost. Herein, we report a novel CTOTM photoresist trimming solution as a post-lithography spin-on method to enhance photoresist performance in not only effectively reducing critical dimension, but also enabling larger process window, lower line width roughness, less scum and lower defectivity. This is a versatile process that is compatible with both acrylic and polyhydroxystyrene types of photoresists, therefore allowing it to become a general process for a wide range of applications across ArF, KrF and EUV lithography.

We had developed various Polyphenols and Xanthene derivatives such as NF7177C and NF0197 which showed high heat resistance. In this paper, we reported on new Xanthene derivatives and Polyphenols with characteristics of not only high heat resistance but also low Tg which contributes to good planarization characteristic of Spin-On Carbon Hardmask [1]. One approach to decrease Tg is introducing alkyl group into the Xanthene derivatives. We synthesized the new Xanthene derivatives by the reaction of dihydroxynaphthalene with the aldehydes containing alkyl group. These Xanthene derivatives containing alkyl group showed lower Tg than those not containing alkyl group by about 20~30°C. Another approach to decrease Tg is increasing flexibility of molecular structure. We synthesized the new Polyphenols (NF71C7, NF71D7, NF91A7, and NF71A7) by the reaction of flexible or asymmetric phenols such as 4,4'- dihydroxydiphenyl ether or 4-phenylphenol. The Tg of these Polyphenols was 70~80°C and these values were much lower than the existing polyphenol (NF7177C) synthesized from 4,4-biphenol by about 50°C. We evaluated heat resistance of these Polyphenols with additive, and both NF71C7 and NF71D7 showed comparable heat resistance to NF0197 and NF7177C.

In the recent semiconductor industry, as the device shrinks, spin-on dielectric (SOD) has been adopted as a widely used material because of its excellent gap-fill, efficient throughput on mass production. SOD film must be uniformly thin, homogeneous and free of particle defects because it has been perfectly perserved after chemical-mechanical polishing (CMP) and etching process. Spin coating is one of the most common techniques for applying SOD thin films to substrates. In spin coating process, the film thickness and uniformity are strong function of the solution viscosity, the final spin speed and the surface properties. Especially, airborne molecular contaminants (AMCs), such as HF, HCl and NH₃, are known to change to surface wetting characteristics. In this work, we study the SOD film thickness as a function of fluorine contamination on the wafer surface. To examine the effects of airborne molecular contamination, the wafers are directly exposed to HF fume followed by SOD coating. It appears that the film thickness decreases by higher contact angle on the wafer surface due to fluorine contamination. The thickness of the SOD film decreased with increasing fluorine contamination on the wafer surface. It means that the wafer surface with more hydrophobic property generates less hydrogen bonding with the functional group of Si-NH in polysilazane(PSZ)-SOD film. Therefore, the wetting properties of silicon wafer surfaces can be degraded by inorganic contamination in SOD coating process.

During the photolithographic process, a photoresist is exposed to EUV photons; it is believed that the secondary low energy electrons generated during this exposure decompose the PAG molecule, producing acid. Regardless of how these secondary electrons are produced, whether by incident electrons or photons, the number of acids produced will lead to a solubility change within the photoresist. The goal of this study is to observe the solubility changing reactions due to low energy electron exposures (approximately 5-80 eV). The reactions occurring in the photoresist are monitored through outgassing measurements during EUV photon exposures, and low energy electron exposures. Outgassing results indicate that PAG decomposition occurs with electrons as low as 4.5 eV, and subsequent deprotection reactions are observed due to the acid generated from the PAG. Without being in the presence of PAG decomposition, deprotection reactions are caused by electron exposures with energies down to at least 15 eV. These deprotections that occur in the absence of PAG decomposition are referred to as direct deprotection reactions. Sentaurus Lithography simulations show that these direct deprotection reactions can affect the resist modeling.

The development of extreme ultraviolet (EUV) lithography towards the 22 nm node and beyond depends critically on the availability of resist materials that meet stringent control requirements in resolution, line edge roughness, and sensitivity. However, the molecular mechanisms that govern the structure-function relationships in current EUV resist systems are not well understood. In particular, the nanoscale structures of the polymer base and the distributions of photoacid generators (PAGs) should play a critical roles in the performance of a resist system, yet currently available models for photochemical reactions in EUV resist systems are exclusively based on homogeneous bulk models that ignore molecular-level details of solid resist films. In this work, we investigate how microscopic molecular organizations in EUV resist affect photoacid generations in a bottom-up approach that describes structure-dependent electron-transfer dynamics in a solid film model. To this end, molecular dynamics simulations and stimulated annealing are used to obtain structures of a large simulation box containing poly(4-hydroxystyrene) (PHS) base polymers and triphenylsulfonium based PAGs. Our calculations reveal that ion-pair interactions govern the microscopic distributions of the polymer base and PAG molecules, resulting in a highly inhomogeneous system with nonuniform nanoscale chemical domains. Furthermore, the theoretical structures were used in combination of quantum chemical calculations and the Marcus theory to evaluate electron transfer rates between molecular sites, and then kinetic Monte Carlo simulations were carried out to model electron transfer dynamics with molecular structure details taken into consideration. As a result, the portion of thermalized electrons that are absorbed by the PAGs and the nanoscale spatial distribution of generated acids can be estimated. Our data reveal that the nanoscale inhomogeneous distributions of base polymers and PAGs strongly affect the electron transfer and the performance of the resist system. The implications to the performances of EUV resists and key engineering requirements for improved resist systems will also be discussed in this work. Our results shed light on the fundamental structure dependence of photoacid generation and the control of the nanoscale structures as well as base polymer-PAG interactions in EVU resist systems, and we expect these knowledge will be useful for the future development of improved EUV resist systems.

This paper describes the photoreactivity of six organometallic complexes of the type Ph_nMX₂ containing bismuth, antimony and tellurium, where n = 3 for bismuth and antimony and n = 2 for tellurium, and where X = acetate (O₂CCH₃) or pivalate (O₂CC(CH₃)₃). These compounds were exposed to EUV light to monitor photodecomposition via in situ mass spectral analysis of the primary outgassing products of CO₂, benzene and phenol. This paper explores the effect of metal center and carboxylate ligand on the EUV reactivity of these EUV photoresists.