This PDF file contains the front matter associated with SPIE Proceedings Volume 11324, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

Complex, three dimensional (3D) assemblies of nanomaterials provide sophisticated, essential functions in even the most basic forms of life. Compelling opportunities exist for analogous 3D structures in man-made devices, but design options are highly constrained by capabilities in fabrication and growth that are primitive compared to those found in biology. This talk describes a collection of recently developed routes to 3D mesostructures that rely on geometric transformation of lithographically defined two dimensional (2D) precursor micro/nanostructures by controlled processes of compressive buckling. We review the key concepts, and highlight some example applications at the bio-interface.

In 1970, Canon introduced its PLA mask aligner tool for the patterning of features on the order of 10 microns. Wafer sizes at the time were on the order of 50 to 75 mm, and circuitry was relatively simple. Since this time, the device landscape and pattern requirements have changed significantly over the last 50 years as has the markets that are served. Sensors and power devices are still made on relatively small wafers, while the integrated circuit manufacturing has standardized largely on 300mm wafers at various resolutions depending on devices or packaging. Displays are manufactured on much larger glass substrates with higher resolution mobile displays on Gen 6 substrates with large television displays up to Gen 10 which are several meters square. Canon has focused on providing a wide range of lithography equipment to cover the complete needs of our customers. From launching the first proximity mask aligners in 1970, in accordance with Moore's law, the lithography equipment has evolved in order to increase the degree of integration of semiconductor devices and reduce the critical dimensions of the devices. As for flat panel display lithography equipment, a mirror projection exposure tool, the MPA was introduced in the early 1980s. In recent years, i-line lithography equipment has been used for advanced packaging, specifically Fan Out Wafer Level Packaging interposers due to the demand for ultra-dense packaging for smartphones and wearables. Most recently Canon has developed a nanoimprint solution for the patterning of advanced memory devices. Imprint lithography is an effective and well-known technique for replication of nano-scale features. Nanoimprint lithography (NIL) manufacturing equipment utilizes a patterning technology that involves the field-by-field deposition and exposure of a low viscosity resist deposited by jetting technology onto the substrate. The patterned mask is lowered into the fluid which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed, leaving a patterned resist on the substrate. The technology faithfully reproduces patterns with a higher resolution and greater uniformity compared to those produced by photolithography equipment. In this paper we review the Canon product line and describe how it is being used to address semiconductor patterning, packaging and flat panel display manufacturing.

The steady advance of nanotechnology from investigation to application and to manufacturing is increasing the demands on nanoscale metrology and lithography and surface chemical analysis. As dimensions shrink to the nano-scale, the available metrologies, necessary for any advanced manufacturing process, become limited. In this seminar we present how we can achieve state of the art results in nano lithography and metrology and possibly NSOM using functionalized III-N nanowires. We will show as, such a single wide-bandgap tip technology offers the functionality and versatility of several incumbent technologies in one single, universal, system.

Although the field of optical lithography is highly investigated and numerous improvements are made, structure sizes smaller than 20 nm can only be achieved by considerable effort when using conventional technology. To cover the upcoming tasks in future lithography, enormous exertion is put into the development of alternative fabrication technologies in particular for micro- and nanotechnologies that are capable of measuring and patterning at the atomic scale in growing operating areas of several hundred square millimetres. Many new technologies resulted in this process, and are promising to overcome the current limitations^{1, 2,} but most of them are demonstrated in small areas of several square micrometers only, using state-of-the-art piezo stages or the like. At the Technische Universitat Ilmenau, the NanoFabrication Machine 100 (NFM-100) was developed, which serves as an important experimental platform for basic research in the field of scale-spanning AFM tip-based and laser-based nanomeasuring and nanofabrication for simultaneous subnanometre measuring and structuring on surfaces up to Ø100 mm. This machine can be equipped with several probing systems like AFM, laser focus probes and 3D-micro probes as well as tools for different nanofabrication technologies like tip-based technologies, optical technologies and mechanical two-dimensional technologies in a large working range with subnanometre reproducibility and uncertainty. In this paper, the specifics and advantages of the NFM-100 will be described as well as nanofabrication technologies that are currently worked on e.g. advanced scanning proximal probe lithography based on Fowler-Nordheim-electron-field emission, direct laser writing and UV-nanoimprint lithography.

Imprint lithography is an effective and well-known technique for replication of nano-scale features. Nanoimprint lithography (NIL) manufacturing equipment utilizes a patterning technology that involves the field-by-field deposition and exposure of a low viscosity resist deposited by jetting technology onto the substrate. The patterned mask is lowered into the fluid which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed, leaving a patterned resist on the substrate. The technology faithfully reproduces patterns with a higher resolution and greater uniformity compared to those produced by photolithography equipment. Additionally, as this technology does not require an array of wide-diameter lenses and the expensive light sources necessary for advanced photolithography equipment, NIL equipment achieves a simpler, more compact design, allowing for multiple units to be clustered together for increased productivity. Previous studies have demonstrated NIL resolution better than 10nm, making the technology suitable for the printing of several generations of critical memory levels with a single mask. In addition, resist is applied only where necessary, thereby eliminating material waste. Given that there are no complicated optics in the imprint system, the reduction in the cost of the tool, when combined with simple single level processing and zero waste leads to a cost model that is very compelling for semiconductor memory applications. Any new lithographic technology to be introduced into manufacturing must deliver either a performance advantage or a cost advantage. Key technical attributes include alignment, overlay and throughput. In previous papers, overlay and throughput results have been reported on test wafers. In this work, improvements to the alignment system, together with the High Order Distortion Correction (HODC) system have enabled better distortion and overlay results. On test wafers, XMMO of 3.2nm and 2.8nm in x and y respectively was demonstrated. There is also an opportunity to further improve results by applying wafer chucks with better flatness specifications. Further advances have also been made through the application of a multi-wavelength alignment strategy. Finally, we discuss how computational methods can enhance NIL productivity and reduce the number of learning cycles

Imprint lithography is a promising technology for replication of nano-scale features. For semiconductor device applications, Canon deposits a low viscosity resist on a field by field basis using jetting technology. A patterned mask is lowered into the resist fluid, which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed, leaving a patterned resist on the substrate. Overlay budgets play a large role in defining production readiness. As an example, DRAM devices require overlay on the order of 15-20% of the half pitch. Canon uses a through the mask (TTM) alignment system to measure a Moiré image anywhere in the field. This system can also record alignment errors of all fields and all marks. The data collected by the TTM system correlates very closely with an Archer measurement tool. In addition, a High Order Distortion Correction (HODC) system, which applies a heat input on a field by field basis through the use of a DMD array has been combined with magnification actuators to correct high order distortion terms up to K30. There is an additional distortion term that must also be addressed for the case of nanoimprint lithography. NIL drop patterns are typically designed to minimize resist fill time and create a uniform residual layer beneath the resist pattern. For device wafers, however, it is important to recognize that there are both long wavelength flatness errors coming from the wafer chuck and existing pattern topography from previously patterned levels that cause out of plane errors. When the mask comes in contact with the resist on the wafer, these out of plane errors can then induce mask bending, resulting in an additional distortion term. To minimize this distortion, a Drop Pattern Compensation (DPC) Model has been implemented to minimize the added distortion terms. In this paper we present an updated study and report on nanoimprint mix and match overlay improvements using DPC. In addition, we describe how the mode array and peak to valley thickness of the resist impacts distortion correction.

The mission of QuTech is to bring quantum technology to industry and society by translating fundamental scientific research into applied research. To this end we are developing Quantum Inspire (QI), a full-stack quantum computer prototype for future co-development and collaborative R&D in quantum computing. A prerelease of this prototype system is already offering the public cloud-based access to QuTech technologies such as a programmable quantum computer simulator (with up to 31 qubits) and tutorials and user background knowledge on quantum information science (www.quantum-inspire.com). Access to a programmable CMOS-compatible Silicon spin qubit-based quantum processor will be provided in the next deployment phase. The first generation of QI’s quantum processors consists of a double quantum dot hosted in an in-house grown SiGe/²⁸Si/SiGe heterostructure, and defined with a single layer of Al gates. Here we give an overview of important aspects of the QI full-stack. We illustrate QI’s modular system architecture and we will touch on parts of the manufacturing and electrical characterization of its first generation two spin qubit quantum processor unit. We close with a section on QI’s qubit calibration framework. The definition of a single qubit Pauli X gate is chosen as concrete example of the matching of an experiment to a component of the circuit model for quantum computation.

Multi-beam mask writers (MBMW) manufactured by IMS Nanofabrication have been increasingly been accepted into mainstream mask making. Over the past decade, this new class of tools has successfully transitioned from the concept, to development and finally to the production phase. Significant technical challenges specific to the architecture were encountered and overcome. Many of these challenges are related to the large image size used by this writer. In this paper, we will review the motivation to develop this new class of writers and the key technical challenges which had to be overcome to realize lithographic promise. Current status and future opportunities to improve the architecture will be discussed.

Laser mask pattern generators (MPGs) write the majority today’s masks. They are the tools of choice for the application spaces of legacy-node chip production and second-level writing for advanced masks. Increasingly, they are also being used to print masks with large data volumes resulting from optical proximity corrections. To improve throughput and print performance for these masks, a software-based data path has been implemented on the ALTA® multi-beam MPG platform. Running on a scalable multicore architecture, the new data path provides more than an order of magnitude increase in processing speed for data preparation and rasterization compared to the existing hardware solution. The programs performing the data preparation and rasterization, along with the general-purpose computers on which they run, are referred to as the raster engine (RE). The RE accepts MEBES®, OASIS®, and GDSIITM formats, optimizes the data on a 0.1-nm grid, and applies both system and user-defined critical dimension (CD) corrections prior to printing. During mask printing, the prepared data are rasterized out to a 0.5-nm writing grid while applying additional corrections required by the ALTA architecture. A beam engine (BE) converts the rasterized data to radio frequency (RF) signals that drive the 32-channel acousto-optical modulator. The edge-placement resolution in the scan direction is controlled using timing rather than grey level interpolation of a fixed pixel grid. The stripe-axis resolution is achieved using fixed beam spacing with 80 gray intensity levels. Significant improvements are observed in the scan-axis print performance and the consistency of corner rounding. This paper also examines the effects of the number of passes used in multi-pass printing on the tradeoff between print quality and mask write times. Finally, the capability to align to the fiducials defined by the SEMI P48 standard for EUV masks has been added to the ALTA system.

This presentation introduces the technology and capabilities of the current ULTRA mask writer by Heidelberg Instruments and explains more in detail the possibilities to enhance the performance by introducing software-based optimizations with the MASKER and BEAMER software tools introduced by Genisys GmbH. We will discuss the results for CD linearity and CD uniformity accomplished by ULTRA, the feature fidelity correction and will also look at plans for further developments.

Multicolumn Electron Beam Lithography (MEBL), a proprietary technology platform developed by Multibeam Corporation, is being applied to enable Security Lithography – a maskless embedding of unique security information into each IC during routine wafer fabrication. This paper focuses on ensuring Secure Chip ID, which provides traceability of a chip throughout its lifecycle and enables confirmation of its unique identity and provenance. The complete MEBL embedding process is disclosed – from chip design to IC fab to verification test. This paper also shows how MEBL hardcoding of the Secure Chip ID “at the silicon level” makes the embedding process cost-efficient and tamperproof.

Bio-sourced and biodegradable polymers for additive manufacturing could enable the rapid fabrication of parts for a broad spectrum of applications ranging from healthcare to aerospace. Herein, we report a resin for vat photopolymerization based on the protein, bovine serum albumin, using a commercially available laser-scanning stereolithographic apparatus (SLA) printer. Methacrylated bovine serum albumin (MA-BSA) was synthesized and formulated into aqueous resins that were used to print complex 3D objects with a resolution comparable to a commercially available resin. The MA-BSA resins were characterized by rheometry to determine the viscosity and the cure rate, as both parameters can ultimately be used to predict the printability of the resin. In the first step of patterning these materials, the MA-BSA resin was 3D printed, and in the second step, the printed construct was thermally cured to denature the globular protein and increase the intermolecular noncovalent interactions. These resins are expected to be compatible with other vat photopolymerization processes, including digital light projection (DLP) and continuous liquid interface production (CLIP).

Increased interest in artificial intelligence coupled with a surge in nonvolatile memory research and the inevitable hitting of the "memory wall" in von Neuman computing1 has set the stage for a new flavor of computing systems to flourish: neuromorphic computing systems. These systems are modelled after the brain in hopes of achieving a comparable level of efficiency in terms of speed, power, performance, and size. As it becomes more apparent that digital implementations of neuromorphic systems are far from approaching the brain's level of efficiency, we look to nonvolatile memories for answers. In this paper, we will build up highly-efficient neuromorphic systems by first describing the nonvolatile memory technologies that make them work, exploring methodologies for overcoming statistical device faults, and examining several successful neuromorphic architectures.

The purpose for this paper is to introduce the SPIE’s semiconductor and biotechnology communities to the emerging and convergent frontier of Semiconductor- Synthetic Biology (SSB). The paper distills and briefly summarizes key messages from two seminal SSB related documents. The first edition of the Semiconductor Synthetic Biology Roadmap,1 published in 2018, laid out a vision for five high impact opportunity areas that complement and leverage the synergistic strengths of semiconductor based information processing technology and synthetic biology. This Roadmap reflects the cross-disciplinary contributions from experts in the physical sciences, health care and semiconductor technologies. A subsequent 2019 paper, by Bathe et. al.,2 elaborated on and further clarified targets for selected biomaterials and biological pathways for electronic nanofabrication. These works are catalyzing considerable research interest and, as with other roadmaps, e.g., the ITRS and IDRS, will tend to prioritize and focus investments in this area. This paper also offers a few early bioinspired SSB-related results with potential high impact that warrant consideration. Note: Throughout the paper, the quoted text comes from reference 1, i.e., the 2018 SemiSynBio Roadmap.

Hydrogen Depassivation Lithography (HDL) is a version of electron beam lithography that uses scanning tunneling microscope (STM) instrumentation to expose a self–developing resist that is a monolayer of H chemisorbed to a Si (100) 2x1 H-passivated surface. Developed in the 1990s it has been largely a laboratory tool used in research for nanofabrication. The technique is capable of atomic resolution, the ability to remove single H atoms from the Si surface and has much higher precision than the best conventional e-beam lithography can possibly achieve exposing polymeric resists. However, its most promising attribute is that it can be used as a digital fabrication tool and is the first of a class of nanofabrication techniques that can be considered digital atomic scale fabrication technologies. Digital Atomic Scale Fabrication can be shown to have similar advantages over analog fabrication techniques that digital information technology has over analog information technology.

Hydrogen deppasivation lithography (HDL) carried out by a scanning tunneling microscope (STM) is used to make patterns of Si dimers on a hydrogen passivated silicon surface. In this paper we discuss a new STM mode of operation that is highly suitable for removing single H atoms from the surface. This is made possible by changes we have made to the STM feedback control system that allows the STM to remove hydrogen atoms without switching the operational mode from imaging to lithography. Employing this method can potentially reduce the chance of tip-sample crash and increase the lithography precision.

The attachment of dopant precursor molecules to depassivated areas of hydrogen-terminated silicon templated with a scanning tunneling microscope (STM) has been used to create electronic devices with sub-nanometer precision, typically for quantum physics demonstrations, and to dope silicon past the solid-solubility limit, with potential applications in microelectronics and plasmonics. However, this process, which we call atomic precision advanced manufacturing (APAM), currently lacks the throughput required to develop sophisticated applications because there is no proven scalable hydrogen lithography pathway. Here, we demonstrate and characterize an APAM device workflow where STM lithography has been replaced with photolithography. An ultraviolet laser is shown to locally heat silicon controllably above the temperature required for hydrogen depassivation. STM images indicate a narrow range of laser energy density where hydrogen has been depassivated, and the surface remains well-ordered. A model for photothermal heating of silicon predicts a local temperature which is consistent with atomic-scale STM images of the photo-patterned regions. Finally, a simple device made by exposing photo-depassivated silicon to phosphine is found to have a carrier density and mobility similar to that produced by similar devices patterned by STM.

Fabrication via self-assembly has been explored for its potential to overcome the challenges of feature size/density and stochastic variability facing conventional lithographic approaches. While methods such as diblock-copolymer directed self-assembly have trouble meeting defectivity and edge-placement specifications, techniques such as atomic layer deposition and self-aligned sidewall-spacer methods are standard. Using DNA origami as an example, I will discuss the conditions for simple systems to form low-defectivity structures, and the potential for self-assembling systems to create complex, hierarchical nanostructures, and their inherent limitation. I will comment on choosing the right applications for the initial introduction of bottom-up fabrication methods.

DNA nanotechnology has shown great promise for nanopatterning applications thanks to the ability to nanoengineer rationally designed two and three-dimensional (3D) nano-objects of complex shapes with subnanometer precision and high degree of rigidity [1]. Recently, a self-assembled DNA origami allowing sub-10 nm pattern transfer into SiO2 has been demonstrated [2]. We report here a mechanistic study of a high resolution (10 nm) and high density (10 nm) DNA pattern transfer into a Si substrate. In order to exploit their full potential for lithographic application, the deterministic positioning of the DNA nanostructures on a predefined substrate is still a major challenge to overcome. In a second part of this paper, we present a hybrid nanopatterning process by combining locally chemically modified substrate by top-down technics with bottom-up self-assembly of DNA nanostructures in order to deterministically fix DNA origamis on the substrate. Chemical contrast is formed using conventional lithography in order to create DNA affine and adverse parts on the substrate. The pattern transfer of the DNA nanostructures in the inorganic under layer is demonstrated as well. Thus, DNA origami appears to be a promising emerging approach for the engineering of hard masks for patterning.

A novel approach to selective electroless deposition of metal on non-conductive substrates was developed. Using an electroless copper process requires the non-conductive material to be catalysed prior to electroless deposition and this is typically carried out using a Pd-Sn colloidal catalyst. In the current work, a novel magnetic Fe₃O₄-Ag nanoparticle (NP) catalyst was used. The composite particles were obtained by a wet chemical method. The composition, particle size and crystal structure of the particles were confirmed by transmission electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. The magnetic properties were characterised by vibrating sample magnetometry whilst the catalytic activity towards formaldehyde oxidation (the key reaction in electroless copper deposition) was confirmed by cyclic voltammetry. Because this new catalyst is magnetic, a magnetic field gradient can be used to manipulate the catalyst NPs. A permanent magnet was attached to the constructed steel template so that a magnetic field gradient on the FR-4 laminate substrate surface was achieved. When the magnetic field was applied, the Fe₃O₄-Ag catalyst NPs were attracted only to the areas of maximum magnetic field gradient on the surface, leading to selective catalysation of the substrate. Subsequent electroless copper plating only occurred at the areas where the composite magnetic NPs were deposited, meaning that selective metallisation by applying a magnetic field was achieved. The width of the selectively metallised lines was 350±20 μm.

Harnessing the omnipresent radio frequency (RF) waves intend to explore the new diode technologies as they determine the frequency of operation and ultimately the power conversion efficiency. Recently, a considerable effort focused on performance, reliable and low-cost fabrication methods. Here, we report the fabrication of sub-20 nm co-planar, asymmetric and self-forming nanogap electrodes by adhesion lithography (a-Lith) as an alternative, low-cost and large-area patterning technique. Moreover, solution processing and rapid Flash Lamp Annealing (FLA) route employed to fabricate Schottky diodes. These diodes are having more than 104 On/Off ratio, low series resistance and junction capacitance due to the novel co-planar architecture and thus operating beyond 10 GHz. This paves the way to a radically new diode technology that has a huge impact on the IoT – Wireless Energy Harvesting (WEH) and RFID system.

A single micro-electromechanical (MEMS) resonator can be shown to exhibit behaviors unexpected in a simple resonant structure. For small driving forces, the resonator displays typical simple harmonic oscillator response. As the driving force is increased, the resonator shows the slightly more complex, but well understood, Duffing response. Rather unexpected response behavior can appear when the resonator frequency is detuned by nonlinearity to where two oscillatory modes of the resonator begin to interact through nonlinear coupling due to an internal resonance. The paper focuses on how the resonator response changes as the internal resonance is approached in the operating parameter space and how that behavior is conveniently represented in a bifurcation diagram. This behavior is accurately captured by a generic mathematical model. We describe an analysis of the model which shows how this coupled response varies with the system and drive parameters, especially focusing on the nonlinear coupling strength between the two modes.

We demonstrate the versatility of dielectric metasurfaces for spatiotemporal shaping of optical fields, and discuss fabrication and material constraints for their applications as flat, ultrathin optical elements across the entire electromagnetic spectrum.

The design and fabrication of the ultra-miniature microlens array homogenizer using two-photon polymerization is presented in this paper. The flat-top laser beam shaper includes refractive type, diffuser type and microlens array homogenizer. The drawback of the refractive and diffuser type is that the uniformity on the homogenization plane is associated with the laser Gaussian beam profile. However, the microlens array homogenizer is independent of laser beam profiles. Therefore, the microlens array is employed for the laser beam shaper in this study. In the simulation, the incident Gaussian elliptical laser beam is successfully transformed into a homogenized rectangular distribution by the microlens array homogenizer. Because the flat-top beam distribution is in the range of micrometer (μm) level in this study, the pitch of the microlens array is reduced to tens of microns, which is not suitable for general machining. Therefore, 3D printing using two-photon polymerization fabrication without tool interference issues is utilized. Finally, the microlens array homogenizer is successfully fabricated. The ultra-miniature flat-top laser beam shaper can accomplish a uniform rectangular distribution of 220 μm X 300 μm, which can be applied for high precision applications such as laser processing, laser medical, and laser display.

Since the 1970s, the cost of photolithography in IC manufacturing has reached nearly 70% of the total production cost. The cost of production lithography equipment has grown almost 160 times reaching ~$80M (193i scanner) and exceeding $200M (EUV scanner). Such high costs have caused a significant market concentration in equipment and chip manufacturing.

Historically, the projection exposure technology was developed on the foundation of geometrical optics. A projection mask was a magnified stencil of the projected pattern. To achieve resolution, extensive development efforts have been made to increase the projection optics numerical aperture (NA), reduce exposure wavelength, minimize distortions of the projection lens and destructive diffraction effects. Complicated and highly costly RETs (OPC, PSM, SMO etc.) are used to suppress distortions in the pattern image induced by diffraction and aberrations of the projection optics.

Sub-Wavelength Holographic Lithography (SWHL) is an unconventional imaging approach in photolithography that utilizes diffraction and interference effects to create high-quality images in photoresist, whilst decreasing exposure steps’ cost, including higher resolution nodes. The ability to construct arbitrary wavefronts opens multiple opportunities like printing on various 3-D surfaces. The SWHL is capable of dramatic reduction of the lithography cost and opens new opportunities in 3D imaging. Two proof-of-concept exposure systems were designed and built to verify the SWHL capabilities: the first for imaging patterns with sub-wavelength resolution, the second for printing on 3D surfaces. The fidelity and computation efficiency of mask synthesis and RET algorithms were verified.

We investigated the contribution ratio of process fidelity and beam accuracy in patterning with the multi-beam mask writing system. A beam pitch-related line edge profile may occur, which impacts on line edge roughness (LER) in the multi-beam writing system. The printability of beam image into the final etched pattern depends on the mask process, therefore, we need to understand quantitatively the printability of beam placement errors on LER with the actual mask process. We examined how the patterning characteristics are modified in each step of the mask process. The printability of beam placement errors largely depend on the period of errors, rather than the amplitude of errors. These results can optimize the writing strategy in multi-beam mask writing.

The high-throughput EBM-mask writer, EBM-8000P has been developed for mature node mask market. The EBM-8000P inherits basic architectures from the previous EBM-8000 system, i.e. electron optics with 50kV acceleration voltage, 400A/cm² current density, variable shaped beam (VSB), and also, user interface such as JOB control system, mask handling system, which are equivalent to our latest single electron beam mask writers.

The EBM-8000P has two models, the EBM-8000P/H, which is equivalent to the conventional EBM-8000, and the EBM-8000P/M, which aims for high throughput.

The mask-writing throughput depends largely on the beam shot size and the current density, based on the generation of mask nodes. The EBM-8000P/M achieves high throughput and enough accuracy for 45-20 node by enlarging the maximum shot size while maintaining a current density of 400A/cm².

Therefore, it is possible to achieve throughput that is 1.5 to 2 times faster than the conventional 70A/cm² mask writer (such as EBM-6000) which is for 45-20nm node.

SWHL Nanotech team have implemented effective algorithms and developed scalable software allowing to synthesize holographic masks for various lithography applications including MEMS, MOEMS and high-end IC production. Most of the technical problems of state-of-art projection photolithography such as 3D-imaging, quality optimization were stated and solved as a completely numerical problems in the case of holographic lithography approach. Nanotech SWHL team developed effective algorithms of the holographic mask synthesis based on FFT with the complexity of 𝑂(𝑁 𝑙𝑛 𝑁), which allowed to synthesize holographic masks for any IC layer. We developed the continuous phase-shifting optimization method based on WFS, DFS and gradient descent, in which a hologram is synthesized not for the original pattern, but for a pattern with altered amplitude and phase distribution. Like in other RET, the holographic mask synthesized for the properly altered pattern provides a much better-quality image of the original pattern. Thus, today it is possible to use modern computing clusters for the synthesis of holographic masks and to implement them in inexpensive and sustainable devices for holographic photolithography.

Sub-Wavelength Holographic Lithography (SWHL) was introduced some years ago by Nanotech SWHL GmbH as a disruptive and promising method to replace projection photolithography. SWHL is based on principles of wave optics and uses a computer-generated hologram (CGH) as a photomask for both 2D and 3D imaging.

To proof the concept of SWHL first for sub-wavelength critical dimensions (CD) and then for non-flat imaging we designed two experimental optical set-ups. Both set-ups use commercially available 442nm He-Cd gas laser. The holographic masks were designed as a set of windows in an opaque chromium layer on a fused silica blank.

The imaging in SWHL does not require any projection optics. Thanks to this the optical system includes only the illuminator of the mask. The illuminator design is very simple, with just a few optical elements.

To demonstrate an image with sub-wavelength resolution, we use illumination with NA 0.53. For this NA we generated image with CD 250 nm that is 0.56 of the wavelength 442 nm.

To demonstrate 3D imaging capability the demonstration lab tool was developed. The tool provides the illumination of holographic mask with NA 0.24. The mask generated a multi-plane image with a depth of 100 μm and the image resolution of 2 μm.

We demonstrated both subwavelength and 3D holographic imaging in experiments and prove the concept of SWHL. All the experiments were made as computer simulations first. The comparison of the simulation and experimental results proved the reliability of our software.

We propose a scheme of maskless holography as a base of a novel lithographic technic. Maskless schemes based on reflective SLMs with planar and non-planar layouts are considered. Several effective methods of phase hologram synthesis adapted to the layouts are also introduced. These methods are based on the holographic lithography approach and calculation algorithms that have been developed by Nanotech SWHL. The aim of the work is to find the proper scheme and SLM characteristics, e.g. micromirror size, flatness, dynamic stability, etc. The non-flat optical schemes based on array of reflective SLMs will allow to achieve high NA up to 0.9 without immersion. That investigation allows to design a photolithographic tool with high diffraction efficiency and high-end capabilities.