Processing from lab to fab: Oxford Instruments drives the compound semiconductor market – An interview by Yole Group

Compound semiconductors are replacing silicon across various sectors, from RF to Power to Photonics. Fueled by megatrends like electrification, digitalization, 5G, autonomous driving, and sustainable energy solutions, the wafer markets, including SiC, GaN, GaAs, and InP, are on a double-digit growth trajectory over the next five years.

According to the Status of Compound Semiconductor Industry 2022 report (2023 edition coming soon), SiC and GaN, considered to be relatively new compared to Silicon, have started shuffling the power electronics industry; new equipment and fabs with high production yields and productivity are needed to compete with Silicon. In this context, equipment vendors have strategically allocated resources towards technology advancement, capacity expansion, and portfolio diversification. Equipment inflection points are seen across the whole chain of compound semiconductor epiwafer and device processing with highest growth expected for deposition, etch, metrology and inspection.

Within this framework, Ezgi Dogmus, Team Lead Analyst in Compound Semiconductors & Emerging Substrates, and Taguhi Yeghoyan, Senior Technology & Market Analyst in Semiconductor Equipment, Subsystems, and Testing, both at Yole Intelligence, part of Yole Group, had the pleasure of interviewing Bas Derksema, the Global Sales and Marketing Director at Oxford Instruments Plasma Technology on their portfolio and strategy in this dynamic and rapidly growing industry.

Taguhi Yeghoyan (TY): Please introduce yourself and your company.

Bas Derksema (BD): Hello, I am Bas Derksema, Global Sales and Marketing Director at Oxford Instruments Plasma Technology.

Oxford Instruments Plasma Technology forms part of Oxford Instruments plc, which specializes in high-technology products and systems that enable customers to image, analyze, and manipulate materials down to the atomic and molecular levels.

Based outside Bristol, UK, Plasma Technology is a leading provider of highly complex and value-added atomic scale processing solutions, with a history and experience of 40 years in plasma deposition and etch equipment. The company has held a leading position in the compound semiconductor marketplace for decades.

We have significant experience and strong foundations in plasma etch and deposition solutions covering all major compound semiconductor platforms, such as GaAs, InP, GaN, and SiC. This is thanks to early engagement with key participants in corporate R&D, academia, and national labs, which has enabled us to understand the market needs and given us a strong foundation for today’s high-volume manufacturing (HVM) customers. We are a knowledgeable, committed, and trusted partner in the development and commercialization of the next generation of CS devices.

TY: Oxford Instruments has long been involved in the processing of compound semiconductors such as SiC, GaN, GaAs, and InP. What was the origin of this involvement?

DB: Innovation is in the DNA of Oxford instruments. We work at the forefront of emerging materials engineering:

Our early involvement in the development of compound semiconductors has enabled us to offer process solutions long before clear market trends and consumer demands have crystallized. This model of operation helps us serve the fast-growing compound semiconductor market effectively today.

TY: What are the general challenges in processing compound semiconductor wafers at the front end?

DB: As the compound semiconductor industry has evolved, a growing number of device makers have more stringent requirements related to the yield and geometry of the processed wafer, sub-nanometer control of plasma etch and deposition processing, control of defects and interfaces, and damage from processes.

This reflects the greater complexity of the design of many of today’s devices. Processing solutions developed for Si are suboptimal. Processing equipment needs to be tailored, and solutions such as atomic-scale processing are needed to align with HVM standards.

TY: What are the differences between power Si and power SiC and GaN device manufacturing?

DB:  The wide band-gap materials offer better performance over a wider operational range than Si and, therefore, enable applications that Si cannot.

The industry is at the crossroads of compound semiconductor solutions and Si semiconductor manufacturing standards.

Therefore, we believe processes and technologies that enable critical inflection points need to be designed for wide-bandgap materials and aligned with HVM standards in order to meet yield requirements and manage cost drivers in these devices.

We decided to focus on process applications that standard Si CMOS manufacturing lines cannot serve.

TY: What are the latest instruments you have released for compound semiconductor processing, and what makes them unique for your clients?

DB: To address the challenges in performance and reliability of GaN-based devices for power electronic and RF applications, we have released a range of Atomic Scale Processing solutions. We have used our expertise in low-damage plasma processing to control interface quality, whilst at the same time transferring to an HVM platform. Our customers really value this unique combination of device performance and reduced manufacturing costs with high throughput and uptime equipment.

Our Atomfab Plasma Atomic Layer Deposition (ALD) system is production-qualified, providing a low-damage in-situ processing solution of surface pre-treatment and deposition of the highest quality oxides and nitrides, as well as dielectric or passivation layers for GaN HEMT manufacturing, with low cost of ownership (CoO).

We have integrated production-proven atomic scale processing solutions for GaN HEMTs at market-leading manufacturers delivering competitive CoO.
Our low-damage plasma pre-treatments and plasma ALD solutions for GaN HEMTs have reduced the manufacturing cost per wafer for this process step by 75%.

We have developed optimized, accurate, low roughness Atomic Layer Etch (ALE) solutions specifically for GaN HEMTs to deliver high-volume manufacturing solutions for current device architectures (pGaN HEMTs) and we also provide reliable production solutions for the development of next-generation GaN devices (such as recessed gate MISHEMTs, vertical FETs, trench MOSFETs).

Automated transfer for both technologies under vacuum for the completion of sequential processing steps in GaN HEMT manufacturing, could lead to improved interface quality by limiting surface oxidation and reducing interface defects, therefore improving device reliability.

Plasma Technology is showing no signs of complacency and continues to invest heavily in all areas of the business.

TY: Compound semiconductors are emerging from niche to high-volume applications in many market segments. What areas of improvement has Oxford Instruments brought to equipment technology for volume production in terms of automation and yield management? 

DB: We have released our Plasma Polish process, a contactless polishing solution to prepare epi-ready SiC substrates. Plasma Polish offers a dry polishing alternative with a lower CoO and environmental footprint while maintaining high yields, solving a critical bottleneck for SiC HVM fabs. We target the key issue in SiC wafers, which is the yield-limiting crystal quality of SiC substrates. Our solution is designed to enhance the crystal quality of SiC substrates, which is a crucial challenge in SiC device manufacturing. 

Oxford Instruments is a market leader in etch and deposition production equipment for InP-based lasers and transceivers. The upcoming AI market in hyperscale data centers is moving production from small substrates processed in small batches to fully automated cassette-to-cassette production at larger wafer sizes. We are enabling this transition utilizing our high-temperature electrostatic clamping (Hot ESC) for the PlasmaPro 100 Cobra ICP etch module, part of our market-leading range of ICP InP etch processing solutions. The Hot ESC capability from 75 mm wafer size and up is a full automation-compatible solution that reduces manual processing for increased reliability and repeatability, which is critical at larger wafer sizes and with more complex processes.

The move to compound semiconductors also plays to our strengths and expertise in combining hardware, materials, software, and process know-how.

TY: Please provide an overview of your inspection instruments for compound semiconductors. Where do you see the inflection points and industry demand?

DB: Beyond Plasma Technology’s products, Oxford Instruments plc offers a wide range of solutions across our portfolio, including EBSD, CR-AFM, and Ultrafast Raman spectroscopy. These advanced metrology/ analytical solutions are needed to mature compound semiconductor material platforms for HVM manufacturing.

Asylum Research AFM technology is critical in the measurement of surface roughness, which is indicative of interface quality and impacts GaN HEMT and SiC MOSFET performance and reliability. Future device generations with vertical architectures will require sidewall roughness.

TY: Would you like to add any closing thoughts for our readers?

DB: As the company grew, we made major investments to enhance our capabilities at Oxford Instruments Plasma Technology. Oxford Instrument’s group executive board has seen this growth and shares our optimism for continued growth in both the near and mid-term. We are now well advanced on the largest investment program in our history and are in the process of moving to our new state-of-the-art semiconductor manufacturing site. Our new site is being created with clean build facilities and a 1,200 m² ISO 5 application clean room to accelerate R&D, customer qualification, and build programs, extending our support for our growing customer base in both production and research markets.

For your readers who are interested in SiC and wide-bandgap materials, we are sharing our recent pioneering development work for SiC surface preparation and evaluation at the International Conference for Silicon Carbide and Related Materials (ICSCRM) from 17^th to 22^nd September 2023. Our presentation is on Thursday 21^st at 9 am, and our team will be available throughout the conference at our booth, No. 3 on floor A, to talk about Plasma Polish and our complementary metrology.