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The Diamond Semiconductor Controversy
In recent years, diamond has gradually become a hot topic of concern in the semiconductor industry.
In order to achieve the goal of green and low-carbon, the semiconductor industry has been continuously pursuing more efficient and powerful semiconductor devices in the past few years. Although traditional silicon materials are widely used, their efficiency is increasingly approaching its limit, especially under high temperature and high pressure conditions. The emergence and development of semiconductor materials such as gallium nitride (GaN) and silicon carbide (SiC) have enabled the industry to break through the limitations of silicon and develop more efficient and sustainable technologies. Today, these materials play a key role in renewable energy systems, electric vehicles, and other technologies that reduce carbon emissions.
However, exploration goes beyond that. Diamond has long been valued for its aesthetic value. Nowadays, after gallium nitride and silicon carbide, diamond has entered the public eye as a new type of semiconductor material and attracted the attention of researchers and industry experts.
01 "Ultimate Semiconductor Materials" have broad prospects
Diamond is an ultra wide bandgap semiconductor that combines excellent electrical, optical, mechanical, thermal, and chemical properties. It is known as the "ultimate semiconductor material" and "ultimate room temperature quantum material". As a new type of material with unique physical and chemical properties, it has a wide range of future applications.
Diamond semiconductors have material characteristics such as ultra wide bandgap (5.45eV), high breakdown field strength (10MV/cm), high carrier saturation drift velocity, and high thermal conductivity (22 W/cmK), which are much higher than the third-generation semiconductor materials GaN and SiC, as well as excellent device quality factors (Johnson, Keyes, Baliga). Using diamond substrates can develop high-temperature, high-frequency, high-power, radiation resistant electronic devices, overcome technical bottlenecks such as "self heating effect" and "avalanche breakdown" of devices, and play an important role in the development of 5G/6G communication, microwave/millimeter wave integrated circuits, detection and sensing fields.
In addition, due to the high exciton binding energy (80meV) of diamond, it can achieve high-intensity free exciton emission at room temperature (emission wavelength of about 235nm), which has great potential in the preparation of high-power deep ultraviolet light-emitting diodes. It also plays an important role in the development of extreme ultraviolet deep ultraviolet and high-energy particle detectors.
By using diamond electronic devices, not only can the thermal management requirements of traditional semiconductors be reduced, but these devices also have higher energy efficiency and can withstand higher breakdown voltages and harsh environments.
For example, in electric vehicles, diamond based power electronic devices can achieve more efficient power conversion, extend battery life, and shorten charging time; In the telecommunications field, especially in the deployment of 5G and higher level networks, the demand for high-frequency and high-power devices is increasing day by day. Single crystal diamond substrates provide necessary thermal management and frequency performance to support next-generation communication systems, including RF switches, amplifiers, and transmitters; In the field of consumer electronics, single crystal diamond substrates can drive the development of smaller, faster, and more efficient components for smartphones, laptops, and wearable devices, leading to new product innovations and improving the overall performance of the consumer electronics market.
According to market research firm Virtuemarket, the global diamond semiconductor substrate market is expected to be worth $151 million in 2023 and is projected to reach $342 million by the end of 2030. The projected compound annual growth rate for 2024-2030 is 12.3%. Driven by the growing demand in the electronics and semiconductor industries in countries such as China, Japan, and South Korea, the Asia Pacific region is expected to dominate the diamond semiconductor substrate market, accounting for over 40% of global revenue share by 2023.
Driven by its unique advantages and broad prospects, diamond has demonstrated enormous potential and value in multiple links of the semiconductor industry chain. From heat sink, packaging to micro nano processing, to BDD electrodes and quantum technology applications, diamond is gradually penetrating into various key fields of the semiconductor industry, promoting technological innovation and industrial upgrading.
However, there are still some prominent issues in the growth of diamond semiconductor materials at present.
02 China, the United States, and Japan compete for diamond semiconductors
The hardness of diamond makes it difficult to grind and process with the precision required by electronic devices. Diamond can also deteriorate during long-term use in semiconductors. Attempting to form larger substrates using diamond is a particular challenge, and cost hinders its commercialization.
But after significant progress in the past few years, diamond semiconductors are expected to enter the commercialization stage between next year and 2030. Japanese manufacturers have made rapid progress in this research and development field.
The Japanese Ministry of Economy, Trade and Industry provides a "Self reliance and Return Support Enterprise Site Selection Subsidy" to support enterprises that build new factories and other facilities in specific areas (such as Fukushima Prefecture Refuge Areas). This subsidy provides financial support for the construction of diamond semiconductor factories.
Orbray, a precision component manufacturer headquartered in Tokyo, has developed technology for large-scale production of 2-inch diamond wafers. They have made 2-inch single wafers on sapphire substrates, breaking the previous limit of 1 inch. The company is expected to develop 4-inch wafers soon.
A research team led by Professor Makoto Kasuga (Semiconductor Engineering) from the Faculty of Science and Engineering at Saga University has successfully developed a semiconductor power circuit using diamond for the first time in the world. It has been proven that high-speed switching and long-term operation, which were previously considered difficult, are possible. If the power circuit can be put into practical use, it is expected to be applied to the latest technologies such as the next-generation communication standard "6G" and quantum computers.
A startup company in Tokyo, Power Diamond Systems, has developed a diamond component that can handle the world's leading 6.8 ampere current. The company plans to start shipping samples within a few years.
Another start-up company in Hokkaido, Ookuma Diamond Device, has raised approximately 4 billion yen, including debt financing, in its Pre-A round of financing. It is currently building a factory in Fukushima Prefecture that will produce diamond semiconductors on a large scale, with the goal of starting operations in March 2026. Diamond semiconductors can withstand high temperatures and radiation, and are therefore expected to be used for the decommissioning of the Fukushima Daiichi nuclear power plant by Tokyo Electric Power Company. According to the company, this is the world's first large-scale production factory.
In addition to Japan, the United States is also actively investing in the research and commercialization of diamond semiconductors.
Last November, the US Department of Energy announced funding for multiple projects to develop next-generation semiconductor technologies, including diamond semiconductors. For example, the University of Illinois has received millions of dollars in funding for projects such as developing light triggered diamond semiconductor switch devices and building high-power diamond optoelectronic devices.
The United States has made significant progress in the preparation technology of diamond semiconductors. Researchers at the University of Illinois at Urbana Champaign have developed a diamond semiconductor device with the highest breakdown voltage and lowest leakage current, highlighting the potential of diamond semiconductors in power grids and other high-voltage applications.
Element Six, a synthetic diamond materials company under the De Beers Group known for developing chemical vapor deposition (CVD) diamond technology and devices, announced that the company will lead a new Defense Advanced Research Projects Agency (DARPA) project: UWBGS (Ultra Wide Bandgap Semiconductor) - Element Six and its partners will develop 4-inch single crystal diamond materials that are more than 10 times larger than currently available materials to accelerate critical electronic technologies.
In addition, the US Defense Advanced Research Projects Agency (DARPA) has commissioned Raytheon to develop ultra wide bandgap semiconductors based on synthetic diamond and aluminum nitride (AlN) to ensure military equipment production in the United States. According to DARPA's contract requirements, Raytheon's advanced technology team will advance this project in stages. In the first phase, the team will focus on developing semiconductor thin films based on diamond and aluminum nitride, laying a solid foundation for subsequent applications. The second phase will focus on researching and improving diamond and aluminum nitride technologies to support the production of larger diameter wafers, especially for sensor applications. These two stages of work must be completed within three years.
Our country is also not willing to fall behind in this field. Xi'an Jiaotong University's Wide Bandgap Semiconductor Materials and Devices Research Center has achieved industrialization of 2-inch diamond. We have taken the lead in realizing the preparation technology of 2-inch single crystal diamond in China, filling the domestic gap. The current indicators are better than the foreign level. The produced single crystal diamond materials have been widely used in 5G communication in China, providing core materials and technical support for high-frequency and high-power detection enterprises. In recent years, the research team at Xi'an Jiaotong University has successfully achieved mass production of 2-inch heteroepitaxial single crystal diamond self-supporting substrates using microwave plasma chemical vapor deposition (MPCVD) technology.
In October of this year, Henan Kezhicheng Third Generation Semiconductor Carbon based Chip Co., Ltd. announced the official production of its diamond wafer production line and released its first product - a 3.5GHz diamond based surface acoustic wave high-frequency filter, marking the end of this new technology route from the laboratory to the production line.
03 aims to avoid China's raw material control in the third-generation semiconductor field
Advanced power chips and RF amplifiers rely on wide bandgap semiconductor materials such as gallium nitride (GaN), but China controls the majority of gallium supply. In July last year, the Ministry of Commerce and the General Administration of Customs issued a notice to implement export controls on gallium and germanium related items, which will be officially implemented from August 1, 2023. Through the export licensing system, China can clarify the end users and uses of these key metal exports to avoid risks to national security and interests.
In terms of production, China has the highest proportion of global gallium production. Germany and Kazakhstan stopped gallium production in 2016 and 2013, respectively. Germany announced in 2021 that it will restart primary gallium production by the end of the year, while Hungary and Ukraine stopped gallium production in 2015 and 2019, respectively.
Gallium metal is typically classified as a "small metal" and is not found alone in nature. It is produced in small concentrations as a byproduct of refineries that focus on other more mainstream raw materials such as zinc or aluminum oxide. If other countries need to restart the production of gallium metal, they will need to build a huge industrial chain, which will be costly and not worth the loss.
With its 3.4 eV bandgap, GaN has become a leading material for high-power and high-frequency semiconductors. However, synthetic diamond has the potential to surpass GaN's ability in applications where high-frequency performance, high electron mobility, extreme thermal management, higher power handling, and durability are crucial (with a bandgap of approximately 5.5 eV). Therefore, the industrialization of diamonds has attracted the attention of the United States and Japan. However, synthetic diamond is an emerging semiconductor material, and its large-scale production still faces challenges.
The US military relies on the properties of gallium nitride to effectively transmit the power of advanced radar under development. Gallium nitride is also used as a substitute for the Patriot missile defense system being manufactured by Raytheon. Only by achieving breakthroughs in diamond semiconductors can the United States and Japan hope to avoid China's material advantages in the third-generation semiconductor field.