While EUV systems equipped with a 0.33 Numerical Aperture (NA) lens are being applied in high volume manufacturing, ASML and ZEISS are in parallel ramping up their activities on an EUV exposure tool with an NA of 0.55.
The purpose of this so-called high-NA scanner, targeting an ultimate resolution of 8nm, is to extend Moore’s law for another decade.
A novel lens design, capable of providing the required Numerical Aperture, has been identified; this lens will be paired with new, faster stages and more accurate sensors enabling the tight focus and overlay control needed for future nodes.
In this paper we will outline the advantages of High-NA, especially for managing the needed extreme low defect printing rates while maximizing the effective throughput for patterning economics. The imaging performance is being simulated based on expected surface figures of the illumination and projection optics. Next to this, an update will be given on the status of the developments at ZEISS and ASML. Buildings, cleanrooms and equipment are being constructed, mirror production is ramping up, many tests are carried out to ensure a smooth implementation.
While EUV systems equipped with a 0.33 Numerical Aperture (NA) lens are entering high volume manufacturing, ASML and ZEISS are in parallel ramping up their activities on an EUV exposure tool with an NA of 0.55. The intent of this high-NA scanner, targeting a resolution of 8nm, is to extend Moore’s law throughout the next decade. The high-NA optical system, together with the developments in mask and resist, provides an increased contrast, key to control stochastic contributions to EPE and the rate of printing defects. A novel lens design, capable of providing the required NA, has been identified; this lens will be paired with new, faster stages and more accurate sensors enabling the tight focus and overlay control needed for future process nodes. Impact on system architecture and proposed solutions are described in this paper. In addition, we give a status update on the developments at ZEISS and ASML.
While EUV systems equipped with a 0.33 Numerical Aperture (NA) lens are entering high volume manufacturing, ASML and ZEISS are in parallel ramping up their activities on an EUV exposure tool with an NA of 0.55. The intent of this high-NA scanner, targeting a resolution of 8nm, is to extend Moore’s law throughout the next decade. The high-NA optical system, together with the developments in mask and resist, provides an increased contrast, key to control stochastic contributions to EPE and error rate of printing defects. A novel lens design, capable of providing the required NA, has been identified; this lens will be paired with new, faster stages and more accurate sensors enabling the tight focus and overlay control needed for future process nodes. Impact on system architecture and proposed solutions are described in this paper. In addition, we give a status update on the developments at ZEISS and ASML.
For each lithography scanner the optics is a key component. While the NXE:3400 with ZEISS Starlith®3400 optics at Numerical Aperture of 0.33 is entering high-volume manufacturing in customer factories, we are developing high NA optics with a Numerical Aperture of 0.55. This optics consists of a highly flexible illumination system and a projection optics enabling single-exposure sub 8nm half-pitch resolution. In this paper, we give an overview of the progress of ZEISS High-NA EUV program where production of first mirrors and frames has already been started.
While EUV systems equipped with a 0.33 Numerical Aperture (NA) lens are readying to start high volume manufacturing, ASML and ZEISS are in parallel ramping up their activities on an EUV exposure tool with an NA of 0.55.
The purpose of this high-NA scanner, targeting a resolution of 8nm, is to extend Moore’s law throughout the next decade.
A novel lens design, capable of providing the required Numerical Aperture, has been identified; this lens will be paired with new, faster stages and more accurate sensors enabling the tight focus and overlay control needed for future process nodes.
In this paper an update will be given on the status of the developments at ZEISS and ASML. Next to this, we will address several topics concerning the interaction of the High-NA optics and its associated different magnifications on requirements for the mask, in particular defectivity, flatness, substrate thermal properties, novel absorbers, need for assist features, pellicle and stitching.
The optical train is a key element of each lithography scanner. The single patterning resolution limit of a scanner is determined by the characteristics and performance of its imaging system consisting of illumination and projection optics. The most relevant performance parameters of the illumination system are the maximum achievable setting flexibility, off-axis imaging capability (sigma) and pupil fill ratio (PFR). The key drivers of the projection optics are numerical aperture (NA), aberration level, and stray light.
In this paper, we present an overview of the current EUVL generation and the optical system, designed to improve resolution limit, contrast and overlay performance within the scanner. The projection optics features a NA of 0.33 with significantly reduced aberration levels. These key scanner parameters have been substantially reduced to improve overlay and image contrast supporting volume production.
While double patterning is a possible extension with the current generation of EUVL tools, there is still a strong desire to print smaller chip patterns directly. Therefore a next generation of EUV called “High-NA EUV” is already in preparation. This tool generation with an optical system -ZEISS Starlith®5000- will have a NA of 0.55 and a resolution of 8nm for direct printing of these finest features. Achieving 8nm resolution means tighter specifications for the wavefront. Therefore, extreme aspheres with improved accuracy of the mirror surface are needed that pose next to the large size of the mirrors and the anamorphic design another challenge to the optics manufacturing. To build these systems a completely new production infrastructure is needed which is under installation in parallel with the product design and technology development. In this paper the current progress of the development will be shown.
EUV technology with its state-of-the-art tool generation equipped with a Numerical Aperture (NA) of 0.33 and providing 13 nm resolution is on the brink of entering high volume manufacturing. Extending the roadmap down to a resolution of 8 nm requires a high-NA successor tool. ASML and ZEISS are jointly developing an EUV scanner system with an NA of 0.55 to enable the continuation of Moore’s law throughout the next decade. In this paper we motivate the top-level requirements of this high-NA tool, deduce implications on system design and present how they are solved in the tool. In particular, we address implications of the high-NA leading to large mirror sizes, introduction of a central obscuration and an anamorphic lens design resulting in the transition from full to half field. A consequence of the high-NA is a reduced depth of focus which is dealt with by an improved focus control of the system. The aberration level of the high-NA tool will be significantly reduced w.r.t. the NA 0.33 tool generation. This is achieved by extreme aspheres accompanied by an advanced mirror manufacturing process with corrections down to atomic scale. To enable mirror manufacturing to this precision the limits of mirror metrology are pushed out by transferring the whole measurement process into vacuum. Finally, we will give an update on the current status of the high-NA tool development and the build-up of the necessary infrastructure.
While EUV systems equipped with a 0.33 Numerical Aperture (NA) lens are readying to start high volume manufacturing, ASML and ZEISS are in parallel ramping up their activities on an EUV exposure tool with an NA of 0.55.
The purpose of this high-NA scanner, targeting an ultimate resolution of 8nm, is to extend Moore’s law throughout the next decade.
A novel lens design, capable of providing the required Numerical Aperture, has been identified; this lens will be paired with new, faster stages and more accurate sensors enabling the tight focus and overlay control needed for future process nodes.
In this paper an update will be given on the status of the developments at ZEISS and ASML. Next to this, we will address several topics inherent in the new design and smaller target resolution: M3D effects, polarization, focus control and stitching.
While EUV systems equipped with a 0.33 Numerical Aperture (NA) lens are readying to start high volume manufacturing, ASML and Zeiss are in parallel ramping up their activities on an EUV exposure tool with an NA of 0.55.
The purpose of this high-NA scanner, targeting an ultimate resolution of 8nm, is to extend Moore’s law throughout the next decade.
A novel lens design, capable of providing the required Numerical Aperture, has been identified; this lens will be paired with new, faster stages and more accurate sensors enabling the tight focus and overlay control needed for future process nodes.
In this paper an update will be given on the status of the developments at Carl Zeiss and ASML. Next to this, we will address several topics inherent in the new design and smaller target resolution: M3D effects, polarization, focus control and stitching.
While 0.33NA EUV systems are readying to start volume manufacturing, ASML and Zeiss are ramping up development activities on a 0.55NA EUV exposure tool, extending Moore’s law throughout the next decade. A novel, anamorphic lens design, has been developed to provide the NA; this lens will be paired with new, faster stages and more accurate sensors and the tight focus and overlay control needed for future process nodes. This paper presents an overview of the target specifications, key technology innovations and imaging simulations demonstrating the advantages as compared to 0.33NA and showing the capabilities of ASML’s next generation EUV systems.
Current extreme ultraviolet (EUV) projection lithography systems exploit a projection lens with a numerical aperture (NA) of 0.33. It is expected that these will be used in mass production in the 2018/2019 timeframe. By then, the most difficult layers at the 7-nm logic and the mid-10-nm DRAM nodes will be exposed. These systems are a more economical alternative to multiple-exposure by 193 argon fluoride immersion scanners. To enable cost-effective shrink by EUV lithography down to 8-nm half pitch, a considerably larger NA is needed. As a result of the increased NA, the incidence angles of the light rays at the mask increase significantly. Consequently, the shadowing and the variation of the multilayer reflectivity deteriorate the aerial image contrast to unacceptably low values at the current 4× magnification. The only solution to reduce the angular range at the mask is to increase the magnification. Simulations show that the magnification has to be doubled to 8× to overcome the shadowing effects. Assuming that the mask infrastructure will not change the mask form factor, this would inevitably lead to a field size that is a quarter of the field size of the current 0.33-NA step and scan systems and reduce the throughput (TPT) of the high-NA scanner to a value below 100 wafers per hour unless additional measures are taken. This paper presents an anamorphic step and scan system capable of printing fields that are half the field size of the current full field. The anamorphic system has the potential to achieve a TPT in excess of 150 wafers per hour by increasing the transmission of the optics, as well as increasing the acceleration of the wafer stage and mask stage. This makes it an economically viable lithography solution.
While EUV systems equipped with a 0.33 Numerical Aperture lenses are readying to start volume manufacturing, ASML and Zeiss are ramping up their activities on a EUV exposure tool with Numerical Aperture of 0.55.
The purpose of this scanner, targeting an ultimate resolution of 8nm, is to extend Moore’s law throughout the next decade.
A novel, anamorphic lens design, capable of providing the required Numerical Aperture has been investigated; This lens will be paired with new, faster stages and more accurate sensors enabling Moore’s law economical requirements, as well as the tight focus and overlay control needed for future process nodes.
The tighter focus and overlay control budgets, as well as the anamorphic optics, will drive innovations in the imaging and OPC modelling.
Furthermore, advances in resist and mask technology will be required to image lithography features with less than 10nm resolution.
This paper presents an overview of the target specifications, key technology innovations and imaging simulations demonstrating the advantages as compared to 0.33NA and showing the capabilities of the next generation EUV systems.
While EUV systems equipped with a 0.33 Numerical Aperture lenses are readying to start volume manufacturing, ASML and Zeiss are ramping up their development activities on a EUV exposure tool with Numerical Aperture greater than 0.5. The purpose of this scanner, targeting a resolution of 8nm, is to extend Moore’s law throughout the next decade.
A novel, anamorphic lens design, has been developed to provide the required Numerical Aperture; this lens will be paired with new, faster stages and more accurate sensors enabling Moore’s law economical requirements, as well as the tight focus and overlay control needed for future process nodes.
The tighter focus and overlay control budgets, as well as the anamorphic optics, will drive innovations in the imaging and OPC modelling, and possibly in the metrology concepts.
Furthermore, advances in resist and mask technology will be required to image lithography features with less than 10nm resolution.
This paper presents an overview of the key technology innovations and infrastructure requirements for the next generation EUV systems.
EUV lithography for resolution below 8 nm half pitch requires the numerical aperture (NA) of the projection lens to be significantly larger than the current state-of-the-art 0.33NA. In order to be economically viable, a throughput in the range of 100 wafers per hour is needed. As a result of the increased NA, the incidence angles of the light rays at the mask increase significantly. Consequently the shadowing and the variation of the multi-layer reflectivity deteriorate the aerial image contrast to unacceptably low values at the current 4x magnification. The only solution to reduce the angular range at the mask is to increase the magnification. Simulations show that we have to double the magnification to 8x in order to overcome the shadowing effects. Assuming that the mask infrastructure will not change the mask form factor, this would inevitably lead to a field size that is a quarter of the field size of current 0.33NA step and scan systems. This would reduce the throughput of the high-NA scanner to a value significantly below 100 wafers per hour unless additional measures are taken. This paper presents an anamorphic step and scan system capable to print fields that are half the field size of the current full field. The anamorphic system has the potential to achieve a throughput in excess of 150 wafers per hour by increasing the transmission of the optics as well as increasing the acceleration of the wafer stage and mask stage. This makes it an economically viable lithography solution. The proposed 4x/8x magnification is not the only logical solution. There are potentially other magnifications to increase the scanner performance while at the same time reducing the m ask requirements.
EUV lithography for resolution below 8 nm half pitch requires the numerical aperture (NA) of the projection lens to be
significantly larger than the current state-of-the-art 0.33NA. In order to be economically viable, a throughput in the range
of 100 wafers per hour is needed.
As a result of the increased NA, the incidence angles of the light rays at the mask increase significantly. Consequently
the shadowing and the variation of the multi-layer reflectivity deteriorate the aerial image contrast to unacceptably low
values at the current 4x magnification.
The only solution to reduce the angular range at the mask is to increase the magnification. Simulations show that we
have to double the magnification to 8x in order to overcome the shadowing effects. Assuming that the mask
infrastructure will not change the mask form factor, this would inevitably lead to a field size that is a quarter of the field
size of current 0.33NA step and scan systems. This would reduce the throughput of the high-NA scanner to a value
significantly below 100 wafers per hour unless additional measures are taken.
This paper presents an anamorphic step and scan system capable to print fields that are half the field size of the current full
field. The anamorphic system has the potential to achieve a throughput in excess of 150 wafers per hour by increasing
the transmission of the optics as well as increasing the acceleration of the wafer stage and mask stage. This makes it an
economically viable lithography solution.
The proposed 4x/8x magnification is not the only logical solution. There are potentially other magnifications to increase
the scanner performance while at the same time reducing the mask requirements.
EUV lithography (EUVL) for a limit resolution below 8 nm requires the numerical aperture (NA) of the projection optics to be larger than 0.50. For such a high-NA optics a configuration of 4x magnification, full field size of 26 x 33 mm² and 6’’ mask is not feasible anymore. The increased chief ray angle and higher NA at reticle lead to non-acceptable mask shadowing effects. These shadowing effects can only be controlled by increasing the magnification, hence reducing the system productivity or demanding larger mask sizes. We demonstrate that the best compromise in imaging, productivity and field split is a so-called anamorphic magnification and a half field of 26 x 16.5 mm² but utilizing existing 6’’ mask infrastructure. We discuss the optical solutions for such anamorphic high-NA EUVL.
EUV lithography for resolution below 9 nm requires the numerical aperture of the projection optics to be significantly larger than 0.45. A configuration of 4x magnification, full field size and 6’’ reticle is not feasible anymore. The increased chief ray angle and higher NA at reticle lead to non-acceptable shadowing effects, which can only be controlled by increasing the magnification, hence reducing the system productivity. We demonstrate that the best compromise in imaging, productivity and field split is a so-called anamorphic magnification and a half field of 26 x 16.5 mm². We discuss the optical solutions for anamorphic high-NA lithography.
New design solutions are available for high-NA EUV optics, maintaining simultaneously superior imaging performance and productivity below 9nm resolution by means of anamorphic imaging. We investigate the imaging properties of these new optics configurations by rigorous simulations, taking into account mask induced effects as well as characteristics of the new optics. We compare the imaging behavior to other, more traditional optics configurations, and show that the productivity gain of our new configurations is indeed obtained at excellent imaging performance.
High numerical aperture (high-NA) extreme ultraviolet (EUV) is one option to enable a higher resolution than EUV can
achieve with single patterning. An industry effort to achieve consensus on the key parameters of high-NA EUV is
described. At high-NA, three-dimensional (3D) mask effects cause a loss of contrast in the image that is recovered by
increasing the scanner de-magnification. This leads to a tradeoff between wafer field and mask size that has considerable
impact on mask cost and scanner cost of ownership.
With higher NA (≫ 0.33) and increased chief-ray-angles, mask effects will significantly impact the overall scanner performance. We discuss these effects in detail, paying particular attention to the multilayer-absorber interaction, and show that there is a trade-off between image quality and reticle efficiency. We show that these mask effects for high NA can be solved by employing a reduction ratio <4X, and show several options for a high-NA optics. Carefully discussing the feasibility of these options is an important part of defining a high-NA EUV tool.
Shipping in 2013, the NXE:3300 is the second generation of ASML’s EUV exposure platform. We review the current
status of EUV optics production for the NXE:3300 tools. Four customer systems of the StarlithTM3300 series have been delivered so far. These sets of optics are characterized by a numerical aperture of 0.33 as well as significantly lower flare and wave-front levels compared to the StarlithTM3100. Meanwhile imaging down to 14 nm node features was demonstrated with the StarlithTM3300 pilot optics. Starting with this generation we introduce a fully new illumination system which allows for setting changes without efficiency loss. In this paper we focus on mirror fabrication and at wavelength qualification results of the optical systems produced so far. We also give an outline of potential solutions for the next generation of EUVL optics using higher NA.
With high NA (>0.33), and the associated higher angles of incidence on the reflective EUV mask, mask induced effects will significantly impact the overall scanner-performance. We discuss the expected effects in detail, in particular paying attention to the interaction between reflective coating and absorber on the mask, and show that there is a trade-off between image quality and mask efficiency. We show that by adjusting the demagnification of the lithography system one can recover both image quality and mask efficiency.
Management of mask defects is a major challenge for the introduction of EUV for HVM production. Once a defect has
been detected, its printing impact needs to be predicted. Potentially the defect requires some repair, the success of which
needs to be proven. This defect review has to be done with an actinic inspection system that matches the imaging
conditions of an EUV scanner. During recent years, several concepts for such an aerial image metrology system
(AIMS™) have been proposed. However, until now no commercial solution exists for EUV. Today, advances in EUV
optics technology allow envisioning a solution that has been discarded before as unrealistic. We present this concept and
its technical cornerstones.While the power requirement for the EUV source is less demanding than for HVM lithography
tools, radiance, floor space, and stability are the main criteria for source selection. The requirement to emulate several
generations of EUV scanners demands a large flexibility for the ilumination and imaging systems. New critical
specifications to the EUV mirrors in the projection microscope can be satisfied using our expertise from lithographic
mirrors. In summary, an EUV AIMS™ meeting production requirements seems to be feasible.
This paper discusses the technological consequences of extending optical lithography down to 50 nm. A total systems approach is used to define the overall error budgets on CD and overlay. The feasibility of extremely high NA optics is studied. With extremely high-NA optics, Depth of Focus decreases and focus control becomes more critical. Using a Step and Scan system, the potential of system dynamics is evaluated. Mask issues are briefly reviewed. Experimental data on field extension with butting is included. As well as being technically feasible, the lithography step for the future technology nodes must be cost effective. It is concluded that optical extension should preferably be supported by reduced field, large magnification scanners. The transition to Next Generation Lithography will be pushed to at least the 50 nm node.
In the same way as 248 nm lithography is now being pushed to 0.15 and even 0.13 micrometers technologies, 193 nm lithography is expected to be used for printing the 0.1micrometers technologies. In this paper, we show results of a simulation study using Prolith 6.0 to investigate the feasibility of printing the 0.1 micrometers dense lines and spaces and 70 nm isolated lines. Since good resists models for 193 nm lithography are not available yet, we extrapolated 248 nm resists models to 193nm and 157nm illumination. First the optimum NA/sigma settings are obtained for printing those features in different illumination modes. Therefore binary masks versus phase shifting techniques and conventional versus off-axis illumination are compared. Maximum DOF and EL for a system without lens aberrations are the main optimization criteria. Consequently CD variations is calculated when a full set of aberrations is taken into account. This realistic set of aberrations has been obtained by scaling down Zernike coefficients measured in 248nm systems and scaled at different RMS levels. Besides lens aberrations also stochastic variations in focus, exposure dose and reticle CD and phase are assumed.
A new European research program named EUCLIDES (Extreme UV Concept Lithography Development System) has been started in August 1998. The program headed by ASM Lithography (ASML), partnered by Carl Zeiss and Oxford Instruments, is evaluating EUVL as a viable lithographic solution for resolutions of 70 nm and below. This paper gives an overview of program objectives and status, including a summary of recent highlights.
SYNERGI is a set of modules developed in collaboration between Thomson TTD Optronique, Pilkington Optronics, and Carl Zeiss. This module set is dedicated to new generation multipurpose high performance thermal cameras based on the SOFRADIR 288 by 4 element IRCCD detector. The manufactured products, as well as the various camera configurations designed, exhibit the key features of SYNERGI: cost effectiveness, compactness, flexibility, reduced power consumption. Special care has been taken in the technical design to minimize noise sources (early video digitization, power supplies synchronization), to maximize boresight stability (specific scan sensor), to enhance image characteristics (zoom modes, digital outputs, external synchronization), to make easy maintenance (dedicated serial link, BITE).
Surface deviations of spherical mirrors from a best fitting, mathematically ideal sphere were measured to an absolute precision of 0.25 nm rms. Because of the long radius of curvature, a Hindle-type arrangement was used as interferometric setup, resulting in a test arm length of about 1.4 m. A special calibration procedure was implemented to eliminate systematic, setup-dependent errors. A very fast data acquisition technique was combined with real-time wavefront averaging to eliminate the effects of random errors, such as wavefront variations due to the turbulent atmosphere in the beam path. For the evaluation of one mirror surface, all in all 400,000 individual wavefront measurements at 400 x 400 points were combined, requiring an overall measurement time of only one to two days.
We will report on a new interferometer developed at Carl Zeiss, which has real-time measuring
capability with instant visualization of results, is nearly insensitive to vibrations, has a variable fringe spacing
from one lambda to lambda/1O (lambda represents the wavelength of the light used in the interferometric
test), and can give lambda/100 accuracy through a simple calibration procedure. It can be handled with the
same ease and in just the same way as conventional interferometers.
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