Plasma-Assisted Polishing of Diamond Semiconductors

This page details TDC’s research on diamond semiconductors, which are currently the focus of much attention, and provides basic information on diamond semiconductors.

TDC’s Role in Diamond Semiconductor and Diamond Substrate Research

TDC, in collaboration with Osaka University and the National Institute of Advanced Industrial Science and Technology (AIST), has been developing innovative polishing techniques for diamond substrates. This project is supported by the Japan Science and Technology Agency (JST) under the A-STEP program.

Traditionally, the most common method for polishing diamond—the hardest material known—has been the “diamond-on-diamond” technique, also known as scaife polishing. However, this method has several drawbacks. It involves high mechanical loads and generates significant heat, leading to surface damage and an increased risk of substrate fracture. This made it challenging to produce thin, large-area diamond substrates similar to silicon wafers. Additionally, the hardness of diamond meant that polishing required a significant amount of time.

To address these challenges, our team developed plasma-assisted polishing. During the research, we discovered that by using a rotating quartz glass plate (a material softer than diamond) and exposing it to argon-oxygen plasma while pressing the diamond substrate against it, it is possible to achieve high-efficiency polishing with low pressure. This method produces excellent surface smoothness, achieving a polishing rate of over 10 μm/h on large-area mosaic single-crystal diamond substrates measuring 20 mm square.

This plasma-assisted polishing technique allows for dramatically improved efficiency (shorter polishing time) and reduced mechanical stress (minimizing the risk of cracks or scratches) compared to conventional methods.

Our research findings have been published in the internationally renowned journal Scientific Reports:

 Scientific reports (English) :
https://www.nature.com/articles/s41598-020-76430-6 

For additional details, refer to the Osaka University press release (Japanese) :
プラズマで実現!ダイヤモンドを傷つけず・素早く・磨く – リソウ (osaka-u.ac.jp)

Award-Winning Research

In September 2021, this collaborative effort earned the 41st (2021) Japan Society for Precision Engineering (JSPE) Technology Award for the development of “High-Efficiency and Damage-Free Polishing Technology for Large-Area Single-Crystal Diamond Substrates Using Plasma Assistance.”

The award recognizes the joint efforts of TDC (commercialization of diamond substrate polishing), Osaka University (development of plasma-assisted polishing technology), and AIST (development of large-area mosaic single-crystal diamond substrates).
The recipients include Professor Yamamura of Osaka University, Dr. Hideaki Yamada of AIST, and Ms. Yuko Akabane (representative of TDC) along with two engineers from TDC.

Precision Diamond Polishing Examples at TDC

At TDC, we offer contract processing services for diamond substrate polishing.

As of 2024, in addition to plasma-assisted polishing, we have developed new polishing techniques that can handle substrates up to 70 mm square, achieving surface roughness in the Sa 0.1 nm range. These results meet the surface quality requirements for applications such as power devices, heat sinks, and optical windows.

For more information on the latest precision diamond polishing processes, please refer to the following page:
>>Precision Polishing of Diamond Semiconductors and Wafers

If you have any inquiries or would like to request diamond polishing services, please don’t hesitate to contact us.

What are Diamond Semiconductors and Diamond Substrates?

Diamond semiconductors (diamond substrates) refer to semiconductors made using synthetic diamond material.

While the use of diamond in semiconductors was once considered technologically unfeasible, recent advancements in research and development, such as the synthesis of diamond thin films, have led to significant progress in the fundamental technologies, opening up possibilities for practical applications.

Compared to traditional semiconductor materials like silicon and silicon carbide (SiC), diamond offers superior properties such as low power consumption, high insulation resistance, and excellent thermal conductivity. As a result, research and development in this field have been rapidly advancing.

Diamond: A Promising Material for Semiconductor Applications

Diamond’s thermal conductivity is approximately five times that of copper. Its refractive index and hardness are the highest among all known materials. Because of these exceptional properties, diamond has historically been used not only as a gemstone and decorative material but also as a tool for cutting and shaping other materials.

If diamond semiconductors are successfully commercialized, they could dramatically reduce power loss in power devices for electric vehicles and trains. Additionally, since diamond’s excellent heat dissipation properties would eliminate the need for heat sinks and cooling systems, this could lead to significant space-saving and weight-reduction benefits.

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