Background: The secondary electron yield (SEY) of materials is important for topics as nanoparticle photoresists and extreme ultraviolet (EUV) optics contamination.

Aim: Experimentally measure SEY and secondary electron energy distributions for Ru, Sn, and Hf oxide.

Approach: The SEY and energy distribution resulting from 65 to 112 eV EUV radiation are measured for thin-film oxides or films with native oxide.

Results: The total SEY can be explained by EUV absorption in the topmost nanometer of (native) oxide of the investigated materials.

Conclusions: Although the relative SEY of Ru and Sn is well-explained by the difference in EUV absorption properties, the SEY of HfO₂ is almost a factor 2 higher than expected. Based on the energy distribution of secondary electrons, this may be related to a lower barrier for secondary electron emission.

Background: The homogeneity of photoacid generator (PAG) is a critical factor influencing the resolving capability and the sidewall roughness of a photoresist, yet fundamental understanding of the PAG homogeneity lacks at the nanoscale.

Aim: We present a methodology, massive cluster secondary ion mass spectrometry (MC-SIMS), to determine PAG homogeneity on a 10- to 15-nm scale at the photoresist film surface.

Approach: MC-SIMS bombards the sample with a sequence of massive Au400^+  4 nanoprojectiles, each separated in time and space, collecting and mass analyzing the coemitted secondary ions from each impact. Each sample is analyzed with one million individual projectile impacts. Analysis of coemission of these independent more than one million mass spectra allows for identification of colocalized molecules within nanodomains ∼10- to 15-nm diameter and ∼10  nm in depth from the film surface, therefore revealing spatial molecular distributions at the nanoscale.

Results: About 85% to 95% of the measurements showed PAG–PAG coemission and over 90% showed polymer–PAG coemission. Ion-exchanging additive increases polymer–PAG coemission.

Conclusions: The majority of PAG molecules exist as small aggregates that are <10  nm in size and such aggregates are highly homogeneously distributed within the polymer matrix. The size of the PAG aggregates can be manipulated by additives through an ion-exchange mechanism.

Background: Continued shrinkage of pattern size has caused difficulties in detecting small defects. Multibeam scanning electron microscopy (SEM) is a potential method for pattern inspection below 7-nm node. Performance of the tool depends on charge control, resolution, and defect detection capability.

Aim: The goal of this study is to develop a method for evaluating the performance of multibeam SEM for 7-nm nodes.

Approach: By developing various standard samples with programmed defects (PDs) on 12 in. Si wafer, we evaluate the performance of multibeam SEM.

Results: The first wafer had line and space (LS) patterns and PDs with varying contrast. A second wafer had various shaped small PDs, ∼5  nm in size in 16- to 12-nm half-pitch LS patterns. A third wafer with extremely small PDs of around 1 nm was fabricated in LS patterns with ultralow line-edge roughness (LER) of less than 1 nm. The first wafer was effective for charge control, whereas second and third wafer confirms resolution and defect detection capability.

Conclusions: A set of minimum three standard wafer samples is effective to confirm the performance of multibeam SEM for below 7-nm nodes. Besides, we proposed a method to verify the LER values measured by a critical-dimension SEM.

In the microelectronics industry, most of the dimensional metrology relies on critical dimension (CD) estimation. These measurements are mainly performed by critical dimension scanning electron microscopy, because it is a very fast, mainly nondestructive method and enables direct measurements on wafers. To measure CDs, the distance is estimated between the edges of the observed pattern on an SEM image. As the CD becomes smaller and smaller, the needs for more reliable metrology techniques emerge. In order to obtain more meaningful and reproducible CD measurements regardless of the pattern type (line, space, contact, hole, etc.), one needs to perform a CD measurement at a known and constant height due to a methodology that determines the topographic shape of the pattern from SEM images. An SEM capable of bending the electron beam (up to 12 deg in our case) allows images to be caught at different angles, giving access to more information. From the analysis of such images, pattern height and sidewall angles can be determined using geometric considerations. Understanding interaction between three-dimensional (3-D) shapes, pattern materials, and the electron beam becomes essential to correlate topography information. A preliminary work based on Monte–Carlo simulations was conducted using JMONSEL, a software developed by the National Institute of Standards and Technology. With this analysis, it is possible to determine theoretical trends for different topographies and beam tilt conditions. Due to the effects highlighted by simulations, the processing of the tilted beam SEM images will be presented, as well as the method used to create a mathematical model allowing topographic reconstruction from these images. Finally some reconstruction using this model will be shown and compared to reference measurements. The overall flow used to process images is presented. First, images are transformed into grayscale profiles. After a smoothing procedure, positional descriptors are computed for specific profile derivatives values. Then, from these descriptors coming from two images of the same pattern taken at different tilt angles, we use a low-complexity linear model in order to obtain the geometrical parameters of the structure. This model is created and initially calibrated using JMONSEL simulations and then recalibrated on real silicon patterns. We demonstrate that the use of real SEM images coming from real silicon patterns with our model leads to results that are coherent with conventional 3-D measurements techniques taken as reference. Moreover, we are able to make reliable reconstructions on patterns of various heights with a single calibrated model. Our batch of experiment shows a three-sigma standard deviation of 10 nm on the estimated height for heights ranging from 50 nm to more than 200 nm. Based on simulations, we are able to reconstruct the corner rounding (CR) from SEM images. However, because our wafer has no CR variability, measurements still need to be assessed on real wafer.

The contamination control of silicon wafer surface is more and more strict. Many investigations have been done to inspect defects on silicon wafer. However, rare studies have been reported on defect component inspection, which is also critical to trace the source of defects and monitor manufacturing processes in time. In order to inspect the components of contaminated particles on silicon wafer, especially with a high-speed, in-line mode and negligible damage, a dual nanosecond pulse laser system with both wavelengths at 532 nm is designed, in which one laser pumps the particles away from the wafer surface with negligible damage, the other laser breaks down the particles in the air above the wafer surface to obtain the emission lines of the contaminated particles by a spectroscopy with intensified charge coupled device. The sensitivity of the dual pulse laser system is evaluated. The particle dynamic process after pump is analyzed. The results in this work provide a potential on-line method for the semiconductor industry to trace the sources of defects during the manufacture process.

Effective measurement of fabricated structures is critical to the cost-effective production of modern electronics. However, traditional tip-based approaches are poorly suited to in-line inspection at current manufacturing speeds. We present the development of a large area inspection method to address throughput constraints due to the narrow field-of-view (FOV) inherent in conventional tip-based measurement. The proposed proof-of-concept system can perform simultaneous, noncontact inspection at multiple hotspots using single-chip atomic force microscopes (sc-AFMs) with nanometer-scale resolution. The tool has a throughput of ∼60  wafers  /  h for five-site measurement on a 4-in. wafer, corresponding to a nanometrology throughput of ∼66,000  μm²  /  h. This methodology can be used to not only locate subwavelength “killer” defects but also to measure topography for in-line process control. Further, a postprocessing workflow is developed to stitch together adjacent scans measured in a serial fashion and expand the FOV of each individual sc-AFM such that total inspection area per cycle can be balanced with throughput to perform larger area inspection for uses such as defect root-cause analysis.

Background: An extreme ultraviolet (EUV) pellicle is necessary to increase the process yield even though the declining throughput is a big concern. However, an EUV metrology/inspection tool for this pellicle has not been commercialized yet.

Aim: The goal of this study is to verify the pellicle/mask inspection feasibility of EUV scanning lensless imaging (ESLI) and verify the impact of contaminants on pellicles depending on their size.

Approach: Through-pellicle imaging was implemented by using ESLI, which uses a high-order harmonic generation EUV source and ptychography. Optical characteristics of various sizes of Fe-contaminated EUV pellicles were evaluated to verify their impact on wafer images.

Results: Large size (∼10  μm) contaminants on the pellicle were found to contribute to the final wafer pattern loss. However, small size (2 to 3  μm) contaminants on the pellicle do not have substantial impact on the wafer image.

Conclusions: The defect detection capability of ESLI for pellicle and mask was confirmed. Therefore, ESLI is useful in applications like pellicle qualification and EUV mask inspection metrology.

Directed self-assembly (DSA) of block copolymers (BCPs) is one of the most promising techniques to tackle the ever-increasing demand for sublithographic 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 of sub-10 nm. 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 fluorine-containing polymeric additive with poly(2-vinylpyridine)-block-polystyrene-block-poly(2-vinylpyridine) (P2VP-b-PS-b-P2VP) and successfully controlled the orientation of the high-χ triblock copolymer. The additive selectively mixes with P2VP block through hydrogen bonding and can reduce the dissimilarity of surface energies between PS and P2VP blocks. After optimizing additive dose and annealing conditions, desired perpendicular orientation formed upon simple thermal annealing. We further demonstrated DSA of this material system with five times density multiplication and a half-pitch as small as 8.5 nm. This material system is also amenable to sequential infiltration synthesis treatment to selectively grow metal oxide in P2VP domains, which can facilitate the subsequent pattern transfer. We believe that this integration-friendly DSA platform using simple thermal annealing holds the great potential for sub-10 nm nanopatterning applications.