Process News 2020

November, 2020

Welcome to the new Process News! Inside you will find all the latest news from Plasma Technology, as well as hearing what our customers are doing. If you want to speak to our experts about anything you read, please contact plasma-experts@oxinst.com and someone will get in touch.

About Oxford Instruments Plasma Technology

About Oxford Instruments plc

Oxford Instruments designs, supplies, and supports high-technology tools and systems with a focus on research and industrial applications. Innovation has been the driving force behind Oxford Instruments' growth and success for 60 years, supporting its core purpose to address some of the world’s most pressing challenges. The first technology business to be spun out from Oxford University, Oxford Instruments is now a global company and is listed on the FTSE250 index of the London Stock Exchange (OXIG). Its strategy focuses on being a customer-centric, market-focused Group, understanding the technical and commercial challenges faced by its customers. Key market segments include Semiconductor & Communications, Advanced Materials, Healthcare & Life Science, and Quantum Technology. Their portfolio includes a range of core technologies in areas such as low temperature and high magnetic field environments; Nuclear Magnetic Resonance; X-ray, electron, laser and optical based metrology; atomic force microscopy; optical imaging; and advanced growth, deposition and etching. Oxford Instruments is helping enable a greener economy, increased connectivity, improved health and leaps in scientific understanding. Their advanced products and services allow the world’s leading industrial companies and scientific research communities to image, analyse and manipulate materials down to the atomic and molecular level, helping to accelerate R&D, increase manufacturing productivity and make ground-breaking discoveries.

Oxford Instruments Plasma Technology offers flexible, configurable process tools and leading-edge processes for the precise, controllable and repeatable engineering of micro- and nano-structures. Our systems provide process solutions for the etching of nanometre sized features, nanolayer deposition and the controlled growth of nanostructures.

These solutions are based on core technologies in plasma-enhanced

deposition and etch, ion-beam deposition and etch, atomic layer deposition, deep silicon etch and physical vapour deposition. Products range from compact stand-alone systems for R&D, through batch tools and up to clustered cassette-to-cassette platforms for high-throughput production processing.

Process News Oxford Instruments Plasma Technology 2020

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WELCOME NOTE

The augmented reality issue

Since the beginning of the Covid-19 pandemic, the newworking from home economy has sustained demand for gaming, notebook, tablets, and accessories. The Compound Semiconductor (CS) industry has benefitted from these social trends and a number of technologies such as 5G, biometric payment & Augmented Reality (AR) are now regarded as key building blocks for how the economywill keep pace with the new challenges faced. The Augmented Reality market therefore remained very active during the pandemic. Some companies had to review their strategy. Magic Leap for example had to narrow its focus to enterprise applications. Other companies carried out new investments. In June, Alphabet’s Google announced it had acquired North, an Amazon backed company that makes smart glasses. In September, Facebook introduced its Project Aria glasses. In this edition, we review some of the technical breakthroughs we have delivered for AR over the last fewmonths. In the coming years, immersive technologies will fundamentally alter how we interact with content. The strongest demand for these technologies is expected to come from industries in the creative economy such as gaming and retail. Over the next five years, the AR supply chain will have to focus on addressing the challenges yet to be solved on performance, cost, and yield. Reducing manufacturing cost is a critical activity for manufacturers using diffractive technology and the expertise of equipment suppliers is key to enabling this roadmap. Reasonable pricing for glasses below $1k will have to be demonstrated to further appeal to consumers, whilst challenges on efficiency, artefact, and privacywill have to be addressed. At Oxford Instruments Plasma Technology, we will continue to maintain our technology & innovation leadership and will partner with our customers to develop new solutions to unlock the potential of AR.

Note by: Stephanie Baclet Senior Technical Marketing Engineer

Process News Oxford Instruments Plasma Technology 2020

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CONTENTS

Contents

16  Oxford Instruments releases new equipment to reduce the cost of AR waveguides – An interview by Yole Développement

12  Oxford Instruments launches Ionfab solution providing large area, high yield manufacturing for Augmented Reality applications

Welcome note

Press releases

Note by: Stephanie Baclet

12  Oxford Instruments launches Ionfab® solution providing large area, high yield manufacturing for Augmented Reality applications

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Technical papers

7  Laser-driven electron accelerator on a chip 8  Plasma processing for fabrication of porous silicon nanoneedles 10  Oxford Instruments enables metalens fabrication

14  Oxford Instruments Joins Quantum Foundry at UCSB as Industrial Partner

15  Oxford Instruments Supplies HLJ Technology Co. Ltd., with Plasma Etch and Deposition Solutions for the fabrication of VCSELS on 6 inch wafers

Process News Oxford Instruments Plasma Technology 2020

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CONTENTS

“The hunger for Augmented Reality and Virtual Reality started many years ago. Pieces like Race in the Pacific, made back in the 1900s, picture very nicely our human need to project ourselves into alternative worlds”.

31  Where are the Flying Cars? – A History of Augmented Reality

22  Top 3 considerations for efficient SRG solutions

Featured articles

White paper abstracts

16  Oxford Instruments releases new equipment to reduce the cost of AR waveguides – An interview by Yole Développement

34  Large Area Slanted Etching for Augmented Reality

35  Augmented Reality: Profile Control for Slanted Etching

22  Top 3 considerations for efficient SRG solutions

36  Atomic Layer Deposition for Quantum Devices

24  SEM Gallery

From our blog

28  The Impact of SRG Manufacturing Quality on AR Headsets

31  Where are the Flying Cars? – A History of Augmented Reality

Process News Oxford Instruments Plasma Technology 2020

The latest solution for slanted surface relief grating etching for augmented reality applications.

Ionfab ®

High Yield. High Efficiency. High Uniformity.

Discover more at: plasma.oxinst.com/Ionfab

Process News Oxford Instruemnts Plasma Technology 2020

TECHNICAL PAPERS Laser-driven electron accelerator on a chip

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Laser-driven electron accelerator on a chip

by: Peyman Yousefi, Chair for Laserphysics, Friedrich-Alexander University of Erlangen-Nuremberg, Germany

Photonics-based laser accelerators are enticing candidates for future particle accelerators. They could reduce the size of current large radio-frequency accelerators by one to two orders of magnitude. This could essentially lead to compact high-energy electron sources for a variety of applications in medicine and high-energy physics. Our research centers on demonstrating the required steps towards this new kind of laser-powered accelerator. To demonstrate such a concept, we use silicon as the substrate material and use a top-down approach to fabricate our desired structures. The fabrication process consists of two major steps, namely electron beam lithography as a high-resolution patterning technique and inductively coupled plasma reactive ion etching (ICP-RIE) as an anisotropic etching technique to transfer the written patterns into the substrate. We write the patterns on a negative tone resist with a reasonable etching durability. After developing the resist, we then etch the silicon substrates by a PlasmaPro 100 RIE Oxford Instruments etcher, using SF 6 and O 2 as the etching components. A good control over the ratio of the two gases is essential to have a perfect anisotropic etching with a high selectivity. The etching starts by igniting a stable plasma in the chamber. Once the plasma is formed, the radicals start to accelerate towards the substrate. Fluorine and oxygen radicals interact chemically with the silicon substrate forming a passive layer of SiOxFy. This prevents lateral etching throughout the process. However an optimized ratio of SF 6 and O 2 is essential to keep the passivation rate and the etching rate in balance. We have developed an etching process with an etch rate of 32 nm/s for a perfect anisotropic etching and smooth sidewalls. Our silicon structures are 3 µm tall with an aspect ratio of 20, making them ideal to perform our experiments around photonics-based particle acceleration.

Figure 1. A two-stage silicon accelerator device fabricated by electron beam lithography and inductively coupled plasma reactive ion etching (ICP-RIE).

Figure 1 shows a two-stage silicon dual pillar accelerator equipped with Bragg reflectors, which is comprised of four solid walls left of the dual pillar photonics accelerator structure in the upper right. This device is capable of delivering accelerated electrons with attosecond pulse durations. An aperture in front is etched for alignment purposes. This device structure together with the attosecond electron bunch generation represent a major breakthrough towards an on-chip laser-driven particle accelerator [1, 2]. See achip.fau.de for more details.

Process News Oxford Instruments Plasma Technology 2020

TECHNICAL PAPERS Plasma processing for fabrication of porous silicon nanoneedles

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Plasma processing for fabrication of porous silicon nanoneedles

by: Nazia Tabassum, Monash University, Australia

Recent advances in biomedical technology involve the use of microneedles made of diverse materials for effective skin delivery. Microneedles consist of vertical arrays of micron-sized projections designed to penetrate the outermost layer of the skin and interface the epidermis and dermis. Microneedles have been demonstrated to facilitate enhanced transdermal delivery of active agents (e.g. macromolecules, nanoparticles, small polar molecules) otherwise impermeable to the skin. However, currently microneedles present number of disadvantages such as limited drug loading capacity and uncontrolled degradation. Recently, the microneedle scale is sizing down to the nano-scale, which could lead to remarkable advantages. Nanoneedles, i.e. micron-sized needles integrating nanoscale features, are particularly promising because of their increased surface area, reduced invasiveness, and pain-free administration. However, precise control of the over degradation rate of micro/ nanoneedles within the skin remains a great challenge. In our lab, we have developed porous silicon nanoneedles (pSiNNs) with tunable porosity, biodegradability and mechanical strength for non-invasive drug delivery that will improve the treatment of various diseases. Nanoneedle arrays with a length of 40-50 µm and a tip diameter below 1 µm are fabricated using Oxford Plasma 100 deep reactive ion etching (DRIE) instrument. The Oxford Instruments’ Plasma DRIE allows us to create sharpened nanoneedle projections that are able to puncture the outermost layers of the skin and facilitate the delivery of therapeutic agents. The fabrication process consists of a UV photolithography patterning step followed by dry etching with the DRIE tool. Following, the nanoneedles are posified in a wet etching process by electrochemical anodisation. Further fabrication details are elaborated in the following paragraphs.

Lithography P-type, low resistivity silicon wafers are used as a starting substrate for the nanofabrication of vertical arrays. For this purpose, a silicon wafer is coated with positive photoresist (AZ®4562) by spin coating. The substrate is further baked at 110 ºC. A chromium mask is used to transfer the defined pattern on the substrate by UV exposure. The photosensitive-coated substrate is lastly immersed in AZ®400K developer solution where the exposed resist is removed to complete the photolithographic patterning of nanoneedles. DRIE Process Si wafers containing photoresist-patterned circles are etched using an Oxford Plasmalab 100 DRIE by performing a Bosch process and by standard dry etching base on RIE. The fabrication of nanoneedle arrays is a three-step process consisting of isotropic sulphur hexafluoride (SF 6 ) step to create a sharp tip, and Bosch process step to obtain cylindrical posts in an anisotropic etching. As a third step, the reshaping of nanoneedles is done with a mixture of SF 6 and octafluorocyclobutane (C 4 F 8 ) gases to obtain sharper tips for enhanced skin penetration. 1. SF 6 only: Firstly, the sharp tip of nanoneedle arrays is created by using isotropic SF 6 etching process with controlled time. In isotropic SF 6 etching, the flow rate of SF 6 gas is adjusted. The ICP generator power and RF power are maintained.

Process News Oxford Instruments Plasma Technology 2020

TECHNICAL PAPERS Plasma processing for fabrication of porous silicon nanoneedles

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2. Bosch process: Bosch etching employs SF 6 and C 4 F 8 gases for the etching and passivation cycles,

Silicon wafers containing nanoneedle arrays are electrochemically etched in a hydrofluoric acid (48%) and ethanol (3:1 volume ratio) solution. The etching is performed at constant current density over a time period. The formed pSi layer thickness is 1.6 µm while the pores displayed a diameter in the range of 4-11 nm. Oxford Plasmalab 100 DRIE instrument thus facilitates to create the required shape of pSiNNs for effective transdermal penetration to deliver bioactive agents into deep skin strata. This DRIE tool also helps in etching hole arrays, nanorods and grating designs for other sensor‑related applications.

respectively. In both the cycles, the flow rate of C 4 F 8 and SF 6 is adjusted. Helium gas pressure is parametrised using the APC valve position and table temperature values. The desired depth of Si etching is proportionally achieved through etching and passivation cycles. The photoresist on the tip of nanoneedles array is later removed with acetone, isopropyl alcohol and water in a sonication bath of around one minute per solvent.

3. Porosification by electrochemical etching of silicon nanoneedles

Process News Oxford Instruments Plasma Technology 2020

TECHNICAL PAPERS Oxford Instruments enables metalens fabrication

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Oxford Instruments enables metalens fabrication

by: Ronghui Lin, King Abdullah University of Science and Technology (KAUST), Saudi Arabia

affect it as long as the rotation angle is maintained. By engineering the rotation angle of each element, and hence the optical phase, the light propagation can be controlled. The SEM image shows a focusing lens with a parabolic phase profile, which is the reason why when we look at the image, there is the optical illusion that the sample consists of rings with different height.

Recently, a new way of making lenses is drawing great attention: instead of the conventional molding and polishing process, the lenses are fabricated using nanofabrication technologies. These lenses are called metalenses. They can be fabricated in batch, namely, hundreds of metalenses can be fabricated simultaneously on the same wafer just like computer chips. The geometries are thin with only a few hundred micros including the substrate (the effective areas is only a few micrometers thick). While such lenses may not be useful for large devices such as giant telescopes, it shows great potential for small and portable devices such as VR display, cellphone camera, and endoscopy. In a conventional lens, the thickness of the material is used to control the phase of the light. However, in a metalens, the phase is controlled by an array of subwavelength structures. Each element in the array behaves like tiny antennas that give a phase shift to the incoming light; Since the spacing between elements is smaller than the operating wavelength, such a patterned surface appears as a continuous surface with continuous phase pattern to the incident light. It provides versatile wavefront shaping capabilities because we are literally engineering the wavefront pixel by pixel. One mechanism to control the local phase is to utilize the Pancharatnam-Berry (P-B) phase. Such a phase can be imposed when circularly polarized light passes through the anisotropic fin-shaped nanostructures. The P-B phase is linearly proportional to the rotational angle of each element. It is a very robust phenomenon. Even the imperfectness from the fabrication (such as shape imperfection and height of the nanostructures) won’t

“To get the highest etching selectivity and vertical sidewall, there are quite a few etching parameters to tune, such as the RF power, ICP power, Cl 2 /BCl 3 ratio, and pressure.”

The sample is composed of GaN nanofins on a sapphire substrate. Firstly, the pattern is designed and written on the wafer by electron beam lithography. Then a layer of Ni is deposited on the wafer after which a lift-off process is carried out. Eventually, a layer of Ni hard mask is left on the wafer. While this is very thin, it is limited by the effectiveness of the lift-off process. The most challenging process in this part is the etching of high aspect ratio nanofins. The width of each nanofin is around 200 nm and the height is ~1.5um, and the narrowest gap is a few tens of nm. We used the Oxford Instruments

Process News Oxford Instruments Plasma Technology 2020

TECHNICAL PAPERS Oxford Instruments enables metalens fabrication

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Rotation: the rotation of nanofin structures which creates a Pancharatnam–Berry phase for metalens applications The metalens pattern is written by electron beam lithography on a GaN epilayer. The pattern has a minimum feature size of 200nm and minimum distance of 100nm. Later a layer of Ni metal is deposited as the etching mask by lift-off process. Finally, a ICP/RIE etching process is used to fabricate the high aspect ratio nanofins. A combination of physical etching using Ar as well as chemical etching using cl2 plasma improves the etching rate . The recipe is optimized to obtain maximum aspect ratio and perfect vertical side wall.

Oxford Instruments systems have a user-friendly interface, which makes the recipe modification and sample loading very easy with minimal manual interventions required. Also, I was able to achieve good repeatability and uniformity over large scale sample surface thanks to the stability of Oxford Instruments systems. Overall my experience with Oxford Instruments is a pleasant one.

PlasmaLab System 100 to achieve this. The etching is in Ar plasma and gas mixture of Cl 2 /BCl 3 , which combines the physical etching of Ar plasma and the chemical etching of Cl 2 /BCl 3 . To get the highest etching selectivity and vertical sidewall, there are quite a few etching parameters to tune, such as the RF power, ICP power, Cl 2 /BCl 3 ratio, and pressure. Two main factors are at play here, on the one hand, we want more chemical etching to achieve higher selectivity because the metal mask is relatively thin. On the other hand, we want more physical etching to get the vertical sidewall. The actual recipe strikes a balance between these two processes. Eventually, by optimizing our recipe, we were able to reach a selectively of around 30 between Ni and GaN and a good sidewall quality.

Process News Oxford Instruments Plasma Technology 2020

PRESS RELEASES Oxford Instruments launches Ionfab solution

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20 May 2020 in consumer applications. Oxford Instruments has built on their widely installed trademarked Ionfab technology with this new and unique hardware

Oxford Instruments launches

configuration to address these challenges. The SRG solution for the AR market provides a tenfold increase of the number of waveguides per wafer for slanted etching, as a result of enhanced process yield on large areas. The significantly increased yield that Ionfab delivers is enabled by numerous technical innovations including a Patent pending ion source beam extraction design. The new Ionfab solution delivers a range of benefits including: • Flexibility: The widest range of slanted angles available for complex combiner design to support optimal optical performance. • Unique Hardware: Proprietary ion beam technology enables high directionality of etch and excellent angle control for maximum yield. • High Yield: Large area uniform etching (rate and angle) enables multiple mould processing in one single wafer, allowing a seamless transition from R&D to volume production.

Ionfab ® solution providing large area, high yield manufacturing for Augmented Reality applications

Oxford Instruments Plasma Technology (Plasma Technology) has launched a revolutionary Ion Beam Etch (IBE) solution delivering the step change needed to address fundamental challenges in manufacturing slanted Surface Relief Gratings (SRG) for Augmented Reality (AR) applications. Slanted SRG is the technology of choice for manufacturing highly efficient in-coupler gratings. However, they are also the most challenging structures to fabricate at high yield and low cost. With this new release, the Ionfab enables the production of high efficiency combiners with slanted

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2021 2022 2023 2024 2025 2026 2027

Number of SRG-based wafers processed per year. 100 wafers processed in 2023 as a reference. Data courtesy of Yole Developpement.

gratings at increased production yields. Reducing manufacturing cost with higher

throughput and increased yield is one of the most critical challenges for market penetration of AR

Process News Oxford Instruments Plasma Technology 2020

PRESS RELEASES Oxford Instruments launches Ionfab

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“In order to address the consumer market, a trio of features will be paramount: form factor, performance and cost,” explains Zine Bouhamri, Technology & Market Analyst, Displays at Yole Développement (Yole). And he adds: “Providing a way to reduce the cost of waveguide manufacturing is a very good path towards addressing these parameters. Were these parameters to be met, alongside a proper use case proposition to the consumer, which is expected around 2023, we anticipate the market to grow at a 105% CAGR by 2027.” (1) As the leading pioneer in the AR field, Plasma Technology is one of the most experienced members of the AR ecosystem. Matt Kelly, Managing Director at Plasma Technology, states:

“We have worked closely with our customers to develop this technology, and have designed a comprehensive, field-proven solution which enables AR optical designers to deliver true immersive AR experience at the cost demanded by the consumer market”. (1) Source: Displays and Optics for AR & VR report, Yole Développement, 2020. For more information on Ionfab please visit: Plasma.oxinst.com/Ionfab For more information on Oxford Instruments’ AR solutions please visit: Plasma.oxinst.com/AR

Process News Oxford Instruments Plasma Technology 2020

PRESS RELEASES Oxford Instruments Plasma Technology Joins Quantum Foundry at UCSB as Industrial Partner

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5 August 2020

Oxford Instruments Plasma

Oxford Instruments Plasma Technology is pleased to announce they have joined the Quantum Foundry at the University of California Santa Barbara (UCSB) to further develop their Quantum technology solutions. The Quantum Foundry at UC Santa Barbara is a next generation materials foundry that develops materials and interfaces hosting the coherent quantum states needed to power the coming age of quantum-based electronics. The mission of the Foundry is to develop materials hosting unprecedented quantum coherence, train the next generation quantum workforce, and to partner with industry to accelerate the development of quantum technologies. Oxford Instruments is proud to be one of the industry partners at the UCSB Quantum Foundry, along with other industry leaders in the Quantum technology ecosystem. Dr Ravi Sundaram, Head of Strategic R&D Markets, Oxford Instruments, commented “Oxford Instruments is delighted to be part of such a strong consortium at UCSB and to support Technology Joins Quantum Foundry at UCSB as Industrial Partner

the development of robust Quantum device fabrication processes for applications in computing, communications. We are committed to providing market leading quantum technology solutions to our customers and partnering with the Quantum Foundry will ensure we continue to be at the forefront of this developing technology.” Dr Tal Margalith, Executive Director of Technology and Industrial Liaison, UCSB Quantum Foundry, said “We are thrilled to have Oxford Instruments on board. Their cutting edge, robust processing solutions tailored for quantum technology device fabrication will help us ensure that there’s an executable roadmap from academic discovery to commercial applications.” Oxford Instruments continues to develop and support market-leading nano-fabrication solutions vital to the manufacture of several quantum device platforms including superconducting qubits (ALD, Plasma etch), Diamond NV Centres (Plasma etch, hard mask deposition), and integrated photonics- based qubits (waveguide etch, single photon detector layers etc.). For more information on Oxford Instruments’ Quantum technology solutions please visit: Plasma.oxinst.com/Quantum For more information on the UCSB Quantum Foundry please visit: https://quantumfoundry.ucsb.edu/

Process News Oxford Instruments Plasma Technology 2020

PRESS RELEASES Oxford Instruments Supplies HLJ Technology Co. Ltd., with Plasma Etch and Deposition Solutions for the fabrication of VCSELS on 6 inch wafers

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1 October 2020

Oxford Instruments Supplies HLJ Technology Co. Ltd., with Plasma Etch

and quality. The in-house line integrated epitaxial structure design, growth, wafer processes and reliability tests. HLJ is committed to providing one- stop VCSEL devices shopping services for global users. Dr. Lai GM of HLJ comments: “We chose Oxford Instruments to supply our ICP etch and PECVD systems because they offer cutting edge plasma processing solutions and unrivalled process support, which will be invaluable to us.” The Cobra ICP and PECVD process solutions are designed to support leading edge device fabrication such as VCSELs. Dr Ian Barkshire, CEO of Oxford Instruments commented: “We are delighted that HLJ has chosen multiple Oxford Instruments systems for the production of high technology VCSEL devices. We continue to strengthen our position as a solution provider for compound semiconductors, including the VCSEL market. This partnership reinforces our commitment to enhance market-leading production capabilities.”

and Deposition Solutions for the fabrication of VCSELS on 6 inch wafers

Oxford Instruments Plasma Technology, a leading supplier of plasma etch and deposition optoelectronics solutions to laser fabrication market announced that HLJ Technology Co. Ltd., based in Hsin Chu, Taiwan has selected multiple Oxford Instruments’ Inductively Coupled Plasma (ICP) etch and Plasma Enhanced Chemical Vapour Deposition (PECVD) systems on cluster platforms for the production of 6-inch VCSEL wafers. HLJ is a pioneer of VCSEL production in Taiwan with an outstanding international reputation. Recently, HLJ had built a mass production line for 6-inch VCSEL wafers to enhance efficiency, and expedite greater control of production lead-times, capacity

Process News Oxford Instruments Plasma Technology 2020

FEATURED ARTICLES Oxford Instruments releases new equipment to reduce the cost of AR waveguides – An interview by Yole Développement

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Oxford Instruments releases new equipment to reduce the cost of AR waveguides – An interview by Yole Développement

Rumors continue to rise about Augmented Reality (AR) headsets being around the corner. Is this the consumer dream? Is it the next generation consumer electronics revolution? All these catchy ideas represent billions of investments from all steps of the supply chain, trying to build upon this momentum. And in the meantime, we are seeing major announcements in the industry. Apart from the investments, the fund raising, the prototypes, we also see companies either scaling down as Magic Leap illustrated for the consumer market, or even disappearing from the landscape. Does it mean that AR will never happen? We don’t think so. As we thoroughly explain in Yole Développement’s (Yole) recent report Displays and Optics for AR & VR 2020, it all comes down to a few things.

Process News © Oxford Instruments Plasma Technology 2020

FEATURED ARTICLES Oxford Instruments releases new equipment to reduce the cost of AR waveguides – An interview by Yole Développement

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First and foremost, we need OEMs to build a compelling use case for the consumer. Without it, there is little chance to convince a broad range of customers, apart from the niches we can already see in gaming and sports, for example. These niches are part of the supply chain that is being built up as we speak. Generally speaking, when mentioning AR headsets, we believe that a triptych of performance, form factor and cost has to be respected. After having had the chance to ask WaveOptics about its advancements in waveguides and AR headsets in general, Yole had the opportunity to go up the supply chain. Zine Bouhamri, Technology and Market Analyst Display at Yole Développement interviewed Oxford Instruments, an equipment manufacturer releasing new equipment specifically targeting the AR market. Stéphanie Baclet, Technical Marketing Engineer and Joao Ferreira Product Manager, kindly share details about this equipment and the company’s vision of the market in general.

devices such as high brightness light emitting diodes (HBLEDs) and Vertical Cavity Surface Emitting Lasers (VCSELs). Joao Ferreira (JF): I am a product manager with responsibility for several plasma product portfolios including the ion beam range. I also worked at Applied Materials on the introduction of new ion implantation products before joining Oxford Instruments eleven years ago. I have over 20 years’ experience in semiconductor equipment manufacturing. YD: AR is a dream that has been promised to consumers for many years now. How do you view the opportunity this market represents? SB: We see AR glasses as the next big step in the wearable technology space. As smartphone sales flatten out, wearables offer an opportunity for growth in the consumer market. If you consider Apple, the success of the Apple Watch and Airpods has driven a 25% Compound Annual Growth Rate (CAGR) in revenue for wearables over six years. Airpods Pro remain supply-constrained despite the high price point. For the AR dream to come true, expertise from many different industries must combine to deliver an engaging and comfortable user experience. We see it from our product portfolio. We are engaged in developments in micro

devices. In the AR market, we are uniquely placed to take our customers from lab to fab as we have been building expertise on etching slanted gratings for the last 20 years. I am Technical Marketing Engineer working closely with optoelectronics device manufacturers to translate requirements of their devices into nanofabrication requirements for plasma processing products. I have been working in semiconductor equipment manufacturing for over 10 years on a range of manufacturing processes for opto-electronics

Yole Développement (YD): Could you please share a little bit about yourself and the activities of Oxford Instruments with our readers? Stephanie Baclet (SB): Oxford Instruments Plasma Technology is a leading supplier of advanced plasma etch and deposition solutions to the compound semiconductor and related materials industry. Established in 1982, we are one of the founding companies

of this industry. We have developed an exceptional

depth of knowledge on material processing of a range of optical

Process News © Oxford Instruments Plasma Technology 2020

FEATURED ARTICLES Oxford Instruments releases new equipment to reduce the cost of AR waveguides – An interview by Yole Développement

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new consumer products. We have developed the hardware and processes to enable good die across the full wafer and make Ionfab the system of choice for AR slanted gratings in volume production. YD: In our opinion the optics are one of the, if not the most, critical parts of AR headsets. But many technologies are competing in terms of optics, such as holographic elements versus the surface-relief grating based ones that you are addressing. How do you view the competition? SB: Several technologies are indeed in competition for the optical combiner and what we have observed over the years is a natural segmentation of these technologies based on use case. There is currently no technology which does it all, whether you are considering cost, Field of View (FoV), image quality, or form factor. Within the surface relief technology space, we offer both blazed and slanted gratings as manufacturers often have to tradeoff between efficiency and manufacturability. Slanted gratings are indeed challenging to manufacture and replicate however they deliver the highest efficiency. Using our expertise in material processing, we enable our customers to gain tighter control over manufacturing tolerances for both types of gratings whilst opening a path towards cost reduction. We also understand the challenges

Shutter

Substrate holder

Ar

Cl 2 , CF 4 , CHF 3

Gas ring for CAIBE

Schematic of a Ion beam processing chamber. The wafer is positioned on a substrate holder which is angled to face the ion source. The angle of the substrate holder can be adjusted to enable angled etching.

LED as an enabler for next generation displays, VCSEL for gesture recognition, surface relief gratings for waveguide combiners and even GaN for 5G and wireless charging requirements. Each of these industries is different in their structure and level of maturity but they are all key to the success of AR. Being at the crossroad of these technologies is an exciting place for Oxford Instruments. As a lab and fab partner, we view these developments as opportunities for business growth and we are allocating our R&D investments accordingly.

YD: You are targeting waveguide manufacturing here with Ionfab. What made you decide to follow that path? JF: Oxford Instruments’ ion beam systems have been used for etching of slanted gratings and fabrication of 3D features for many years. Our systems have been used by pioneers of this industry from the very early days. With the recent developments in AR and the adoption of waveguide technology in AR head-sets, in particular slanted surface relief gratings, we recognized that a solution for increased wafer yield and lower cost of ownership is fundamental to enable our customers to successfully develop and launch exciting

Process News © Oxford Instruments Plasma Technology 2020

FEATURED ARTICLES Oxford Instruments releases new equipment to reduce the cost of AR waveguides – An interview by Yole Développement

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without changing hardware. We focused on hardware and process development as well as serviceability to enable our customers to unlock the AR opportunity. YD: What do you make of the competition from dry etching equipment manufacturers? SB: We value competition. We constantly analyze the activity in this marketplace, and we can say that our product readiness level and expertise are unique. Angled etching is a challenging process to demonstrate at large wafer size and we have a decade of experience across our ion beam team. YD: If the consumer dream is fulfilled, we would be talking about millions of waveguides to produce a few years from now. What kind of throughput can you deliver with Ionfab? What is your development roadmap to further enhance your tool? JF: Throughput is very specific to a device structure so I would not like to give an absolute number. However, we know that maximizing the number of good devices per day alongside device performance are critical to our customers, so we have developed the solution to deliver this. The product that we just launched increased the throughput tenfold. Etch rate, for example, is enhanced by controlling the ion flux and the system is combined with industry standard cassette

Slanted grating with excellent profile control. Processing completed by Dr Sebastien Pochon and Dr David Pearson, Oxford Instruments.

YD: How long have you been developing this tool? And what are the key specifications that needed to be developed compared to a dry etching tool commonly used in semiconductor manufacturing? JF: Ion beam is a specialized tool that has very specific advantages over regular plasma etch tools, such as Inductively-Coupled Plasma (ICP) etch. For example, the high degree of collimation of the ion beam and selectable ion energy and angle of incidence means that you gain superior control over etching profile. In the last three years we ran a major development program on ion beam to deliver unmatched uniformity, depth and angle, over a large area as well as the flexibility to do this at various angles

in building a uniform eye box and we have capabilities built into our equipment to support optical designers. YD: Can you please expand on what you are bringing to the industry with Ionfab that was not available before? JF: As mentioned before, our proprietary ion beam technology has been used for many years in the corporate lab environment. Our new product builds on this know- how and adds the ability of processing multiple devices at the same time, the flexibility of selectable slanted angles, and the possibility of depth and angle modulation, while enabling low cost of ownership. Our product increases the number of waveguides per wafer for slanted etching by a factor of ten.

Process News © Oxford Instruments Plasma Technology 2020

FEATURED ARTICLES Oxford Instruments releases new equipment to reduce the cost of AR waveguides – An interview by Yole Développement

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cost is a critical activity for manufacturers using diffractive technology and the expertise of equipment suppliers is key to enabling this roadmap. Besides, global social trends affecting consumers and the new “working from home” economy drive the need for more and richer interactive online experience. AR is seen as a potentially very engaging platform and with increased investment from companies such as Apple, we expect the value proposition to strengthen thanks to a growing AR software and app ecosystem. YD: Would you have a final word for our readers? SB: My last word to readers would be come and talk to us. We are a team with great expertise in our field and we would love to hear about your technology and enable you and your devices to deliver on the promises of AR.

stamp and replica technique. This method is currently the most mature in the market as it benefits from the availability of high refractive index resin. The master is of extremely high value and the quality of the surface relief gratings is critical to the efficiency of the combiner. It is a key step in the supply chain. Our products can also be implemented in alternative approaches such as direct etching of high refractive index glass. We are working on multiple approaches with organizations that are well respected in the industry and we are continually enhancing our product roadmap based on these insights. YD: How do you see the AR consumer market in five years from now? SB: With companies like Oppo releasing AR products, we expect the AR ecosystem to grow as the supply chain for these new products is built. Products from Apple internal projects, publicly reported as N301andN421, arealsoeagerly anticipated. Over the next five years, the AR supply chain will have to focus on addressing the challenges yet to be solved on performance, cost, and yield. Reducing manufacturing

“Slanted gratings are indeed challenging to manufacture and replicate however they deliver the highest efficiency. Using our expertise in material processing, we enable our customers to gain tighter control over manufacturing tolerances for both types of gratings whilst opening a path towards cost reduction.”

wafer handling solutions for reliability and efficiency. With regards to the development road map, we are making strides to further build on our capability for thickness and angle modulation. We continue to invest, and we are addressing primary and secondary customer benefits. YD: Where do you position yourself within the waveguide manufacturing supply chain? Do you support the master design that comes before nanoimprint lithography? Or direct fabrication of waveguides through etching? SB: Our solution targets the fabrication of masters in the

JF: We are very excited about what this product

has to offer as it addresses the key challenges that AR manufacturers face today. It is without doubt a game changer for the production of AR devices. We are confident that our customers will be as excited as we are.

Process News © Oxford Instruments Plasma Technology 2020

FEATURED ARTICLES Oxford Instruments releases new equipment to reduce the cost of AR waveguides – An interview by Yole Développement

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Stéphanie Baclet has

João Ferreira joined Oxford Instruments Plasma

As a Technology & Market Analyst, Displays, Zine

worked for over 10 years in the

semiconductor industry. She works closely with optoelectronics device manufacturers to translate requirements of their device characteristics into nanofabrication requirements for plasma processing products. She has worked as a Senior Application Engineer focused on new plasma product introduction and developed processing techniques for various technologies such as HBLED, Laser diodes, and transistors.

Technology in 2009 as a Project Manager to oversee the development and introduction of new products. In 2017 he joined the Product Management team to manage the Ion Beam team and product strategy. Currently he is a Product Manager with responsibility over several plasma products including the Ion Beam product. He graduated in Physics from Instituto Superior Tecnico, Lisbon and completed an MBA in general Management later at the University of Brighton, UK. He has been working in semiconductor equipment manufacturing for over 20 years.

Bouhamri, PhD is a member of the Photonics, Sensing & Display division at Yole Développement (Yole). Zine manages the day to day production of technology & market reports, as well as custom consulting projects. He is also deeply involved in the business development of the Displays unit activities at Yole. Previously, Zine was in charge of numerous R&D programs at Aledia. During more than three years, he developed strong technical expertise as well as a detailed understanding of the display industry. Zine is author and co-author of several papers and patents. Zine Bouhamri holds an Electronics Engineering Degree from the National Polytechnic Institute of Grenoble (France), one from the Politecnico di Torino (Italy), and a Ph.D. in RF & Optoelectronics from Grenoble University (France).

Dr David Pearson, Ion

Dr Sebastien Pochon, Principal Applications Engineer, Oxford

Beam Technical Specialist, Oxford Instruments. David

is responsible for developing new technology relating to ion beam systems and providing expertise to other departments. His expertise and experience covers both deposition, etch processes and equipment development. He received his PhD in Condensed Matter/Nuclear Physics from Sheffield University. Over the past 40 years, he has previously worked in plasma fusion research and plasma and ion source development in the semiconductor industry.

Instruments. Sebastien is responsible for developing cutting edge processes from metals, to laser facet etching to deposition of AR and HR optical coatings for research to production customers. He received his PhD in Laser Physics from Southampton University, received an MSc in Applied Optics from Salford University as well as an undergraduate degree from Manchester Metropolitan University in Applied Physics and Material Sciences.

Process News © Oxford Instruments Plasma Technology 2020

FEATURED ARTICLES Top 3 considerations for efficient SRG solutions

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1 2 3 Top 3 considerations for efficient SRG solutions

Processing area

Ion shadowing

Angle control

Not all technologies are equal to process large wafer areas. Oxford Instruments delivers 200 mm processing wafer areas.

For small pitch features required for Augmented Reality combiner, you should consider highly directional etching to deliver good angle control.

A mask too thick will lead to ion shadowing and poor profile definition.

Process News © Oxford Instruments Plasma Technology 2020

FEATURED ARTICLES Top 3 considerations for efficient SRG solutions

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1 2 3

How is the angle defined? How is parallelism controlled? Due to the slanted structure, the process is highly subjected to ion deflection which results in asymmetric etching and therefore loss of control over the angle. However, not all techniques are equal. Many techniques based on plasma technology are either complex, costly or cannot guarantee a good etch rate and profile uniformity over a large area. Ion beam etching offers the best way of providing physico-chemical etch directionality. Ion beam processing operates at much lower gas pressures than other plasma techniques. This allows for less gas scattering and better profile control. Do you have a suitable mask? The periodicity of the features depends on the application. For AR headsets, the typical period for waveguide combiners is around from λ /2 to λ which results in grooves around 100 to 200 nm. These dimensions require the use of finer lithography equipment such as E beam lithography or Nano imprinting. Without a clearly defined mask structure, defects can be transferred to the features during process. It is therefore critical to characterise the profile of the mask before etching. Common SEM characterisation can be used to image the mask however the evaluation has to be done on the full surface of the wafer. Once the mask processing is well understood and controlled, optimum yield can be achieved during the slanted etching process. What is the uniform processing area? The target uniformity across wafer is defined by the requirement of the application which includes the die size, and number of dies per wafer. However, depending on the design on the etching reactor, the area matching the target uniformity might not correspond to the full wafer size. The edge exclusion can be as large as 40mm. The large edge exclusion results from non-uniform ion distribution. When dry etching at an angle, the etching depth tends to be higher in the area closer to the ions source. Equipment manufacturers can either adjust the ions distribution or use ion shadowing to compensate for the non-uniform ion distribution. Both methods can be finely tuned to maximize the uniformity of the process.

Process News © Oxford Instruments Plasma Technology 2020

FEATURED ARTICLES SEM gallery

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Customer gallery These beautiful results were achieved on our Plasma Processing equipment. Submit your results today to feature in our Gallery. Visit: plasma.oxinst.com/customer-gallery

4 Framing the picture with electrons The nanoscale ‘plant’ in the picture is a crystalline dendritic structure of a metallic alloy in a solid-electrolyte film. Rastering Electron beam in an oxford Instrument system induces spontaneous self-assembly of the embedded nanoparticles, such that all the nanoparticles are repelled towards the boundaries; the agglomerated nanoparticles at the edges frame the nanoscale plant. The sample was created on the Oxford Instruments PlasmaPro 800. Submitted by Ghazi Sarwat Syed, University of Oxford.

1 Faraday cage angled-etching of nano-beams in bulk of single crystal quartz Through a Faraday cage angled-etching process, single crystal suspended nano-beams on Quartz wafer are fabricated on the Oxford Instruments’ PlasmaLab 100 and ICP 300 Deep RIE. Submitted by Mohammad Hadi Khaksaran, Sabanci University, Turkey.

2 CNT-thorny nano-well Carbon nanotubes (CNTs) were grown using the Oxford instruments Nanofab

system. Submitted by Preeti Kaushik, Masaryk University.

3 Metal Pipeline Maze Anisotropic dry SiO 2 etch by means of the Oxford Instruments PlasmaLab 100 ICP System. Submitted by Albert Guerrero Barbero, Institute of Microelectronics of Barcelona IMB CNM.

Process News © Oxford Instruments Plasma Technology 2020

FEATURED ARTICLES SEM gallery

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5 How many squares are in the picture? Isotropic etch with SF 6 performed through slits (2x5 micron) and trenches (2 micron wide) in SiN on the Oxford Instruments PlasmaPro 100. Submitted by Henk-Wellem Veltkamp, University of Twente. 6 The Mighty Dust Particle A thin film of amorphous hydrogenated silicon carbide is deposited on a silicon substrate. The a-SiCx layer was patterned anisotropically using photoresist followed by isotropic etching of the silicon layer from the underneath. All the three etching steps were performed on the Oxford Instruments PlasmaLab 100. Submitted by Amruta Ranjan Behara, Indian Institute of Science.

7 Earth 2050 Alignment marks on a Silicon Wafer after a Deep Reactive Ion Etching of 50 microns using Bosch Process on the Oxford Instruments PlasmaLab 100 system. Submitted by Amlan Kusum Mukherjee, TU Darmstadt 8 Brain on Chip The first example of a brain-on-chip created by a top- down approach. It resembles the brain of a real micro-technologist. This beautiful wavy pattern was obtained after ion beam etching un-baked Olin OIR photoresist. The ion beam etching was done on the Oxford Instruments Ionfab 300. Submitted by Henk- Willem Veltkamp, University of Twente

9 Pseudo-wet Etching 5 µm-wide circular holes in Si Crystallographic etching using Plasmalab RIE. Performance matches wet etching quality with added control on cavity shape. Results achieved on well defined process window using SF 6 /O 2 chemistry. The Oxford Instruments Plasma RIE system was used in this process. Submitted by Hadi Izadi, Yale University.

Process News © Oxford Instruments Plasma Technology 2020

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