In recent years, major international silicon carbide manufacturers have accelerated the development and mass production process of 8-inch wafers. Silicon carbide leader WolfSpeed has launched and started trial production of an 8-inch new factory under its umbrella, with significant revenue expected in the first half of next year. French semiconductor company Soitec has released its first 8-inch SmartSiC wafer. Wafer foundry Liandian will also increase equipment investment and lay out 8-inch wide bandgap semiconductor wafer manufacturing. Currently, the global silicon carbide industry is still dominated by 6 inches. However, from the development experience of silicon-based semiconductors, every improvement from 6-inch to 8-inch and then to 12-inch wafers will have a significant impact on the industry. As major manufacturers accelerate their 8-inch mass production pace, the 8-inch era of silicon carbide wafers is gradually approaching.
Large factories accelerating mass production of 8-inch wafers
On April 26th, Wolfspeed, the world's largest silicon carbide supplier, announced the opening of its new silicon carbide manufacturing plant in Mohawk Valley, New York, USA. The first batch of silicon carbide wafers had already begun manufacturing earlier. This factory adopts 8-inch silicon carbide wafer processing technology and is also the world's first 8-inch production line. The start of trial production of this factory will accelerate the transition of the silicon carbide industry from 6-inch to 8-inch wafers. Wolfspeed Senior Vice President of Global Operations, Rex Felton, stated that the company is also building a materials factory in Durham, North Carolina, USA, which is expected to be completed later this year. At that time, greater synergy will be formed with wafer manufacturing factories.
French semiconductor material company Soitec Semiconductor recently released its first 8-inch silicon carbide SmartSiC wafer. It is reported that the product was produced on the experimental line of the substrate innovation center in collaboration with Soitec and CEA-Leti company. Soitec also launched the construction of a new wafer factory in March this year to produce 6-inch and 8-inch silicon carbide wafers. The new factory is expected to be operational in the second half of 2023.
Semiconductor foundry Liandian has also recently laid out and produced wide bandgap semiconductors, focusing on the more promising 8-inch wafer manufacturing. It is currently investing heavily in new equipment and is expected to enter the factory in the second half of the year. Bu Rixin, General Manager of Chuangdao Investment Consulting, said, "The expansion of Liandian's 8-inch wide bandgap semiconductor manufacturing means that wide bandgap semiconductors are evolving towards large-scale and low-cost directions
From the current global market situation, the main manufacturers in the silicon carbide field include Wolfspeed, Soitec, Italian Semiconductor, Infineon, Rom, and others. After entering 6-inch production, these companies have actively promoted the development of silicon carbide towards 8-inch in recent years. Data shows that in 2015, Wolfspeed displayed an 8-inch silicon carbide substrate. In May 2019, Wolfspeed announced a $1 billion investment in the construction of a new Mohawk Valley factory. Soitec announced a five-year investment plan in 2021, which will invest 1.1 billion euros within five years to double its annual production capacity. At the same time, two new silicon carbide wafer factories will be built, one is 6 inches and the other is 8 inches. In 2019, Yifa Semiconductor acquired Northe Company and renamed it Yifa Semiconductor Silicon Carbide Company. Jean MarcChery, President and CEO of Italian Semiconductor, stated in a previous interview with reporters that the acquisition of Norstel Company fills the manufacturing technology of Italian Semiconductor's silicon carbide wafers. In the future, Italy France Semiconductor will carry out production and development of 8-inch silicon carbide wafers, and plans to take the lead in manufacturing power diodes, MOSFETs, and other products on 8-inch silicon carbide wafers.
The arrival of the 8-inch era will take 5 to 6 years
SiC has the characteristics of high breakdown electric field, high saturated electron velocity, high thermal conductivity, high electron density, and high mobility, making it a good semiconductor material. Currently, it has been widely used in fields such as automotive electronics and industrial semiconductors. After entering 8 inches, the theoretically available number of bare chips in each wafer will greatly increase. According to the data in Wolfspeed's financial report, upgrading from 6-inch to 8-inch wafer processing costs alone increases wafer costs. However, the number of excellent bare chips (dies) obtained from 8-inch wafers can increase by 20% to 30%, resulting in higher production and ultimately lower chip costs.
Gianfranco DI MARCO, Market Communication Manager, Power Transistor Division, Automotive and Discrete Device Products Division, Italy Semiconductor, stated that the development history of silicon based semiconductors proves that switching to larger wafer sizes can improve productivity. This is one of the main reasons why more and more manufacturers are actively promoting 8-inch wafers.
But upgrading to 8-inch silicon carbide wafers is not easy, and even if a few companies can successfully mass produce 8-inch wafers, it does not mean that the 8-inch era of silicon carbide has arrived. IGBT inventor B Jayant Baliga pointed out during his speech that silicon carbide power devices can achieve the functionality of traditional devices with shorter channel lengths and smaller unit sizes. However, compared to silicon based semiconductor materials, silicon carbide substrate growth is extremely difficult and slow, and the process of 8-inch and 6-inch silicon carbide wafers is greatly different and more complex.
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General Manager and Weiwei of Shenzhen Basic Semiconductor Co., Ltd. also stated that the technological challenges in the transition of silicon carbide from 6 inches to 8 inches are mainly reflected in several aspects: firstly, the problem of expanding the diameter growth, from 6 inches to 8 inches. If physical vapor transport (PVT) is still used to prepare silicon carbide substrates, it is necessary to improve the efficiency of raw material transportation, solve the problem of polycrystalline nucleation at the edge of seed crystals, solve the problem of multimodal phase transformation, and improve crystal quality, This requires further improvement of the growth device and optimization of the growth process. The second issue is temperature field control. Changing from a 6-inch crystallization furnace to an 8-inch crystallization furnace will result in a decrease in the accuracy of temperature control by the equipment, which will pose greater challenges. The third issue is the formation of crystal growth and cutting stress. The larger the crystal size, the greater the internal stress of growth, and the greater the cutting stress. The stress release after chip cutting can lead to the occurrence of warping problems, and new cutting techniques need to be developed to address this issue.
Although Wolfspeed has started trial production of 8-inch silicon carbide wafers, and other major international factories are also advancing towards 8-inch production, the entire silicon carbide industry is not expected to enter the 8-inch era overnight, and it is expected to take another five to six years of transition time to complete. It is only around 2028 that the global silicon carbide industry is likely to truly enter the era of 8-inch mass production. This cycle is relatively long, and during this period, 6-inch silicon carbide will still maintain a large market share.
Industrial Collaboration to Meet the Challenges of the 8-inch Era
Although 6-inch silicon carbide wafers are still mainstream, the release of 8-inch silicon carbide wafer production capacity will not have a short-term impact on the industry. However, Chinese enterprises should now face this challenge and actively respond to it. Experts point out that 8-inch wafers have problems such as high material growth difficulty, high cutting difficulty, and high cutting loss. At present, the yield of 8-inch wafers is definitely low, and the final product device price will not be much cheaper than 6-inch wafers. Therefore, putting 8 inches into the market in the short term will not have a significant impact on the industry. However, in the long run, with the advancement of technology, issues related to material growth and cutting processes will inevitably be overcome. For example, Infineon acquired Siltecra, which developed a cold cutting technology that can reduce raw material loss to 50%. The final price of chips on 8-inch wafers will inevitably be lower than that on 6-inch wafers, while there will be a significant increase in production capacity. As costs decrease, production increases, and scale expands, further driving costs down will form a positive cycle. Once such a cycle is formed, the impact on the original industrial pattern will be enormous.
At present, in the field of silicon carbide substrate materials in China, the mass production line is still mainly based on 6 inches, and it is still difficult to produce 8 inches. According to data, among the current silicon carbide manufacturers in China, companies with 6-inch production lines include CRRC, San'an Optoelectronics, China Resources Microelectronics, Jita Semiconductor, Yandong Microelectronics, etc. Some companies are also laying out the development of 8-inch silicon carbide substrates, such as Tianke Heda, which launched the research and development of 8-inch silicon carbide in 2020. Hefei Luxiao Technology has invested 10 billion yuan in the construction of silicon carbide equipment manufacturing, long crystal production, substrate processing, epitaxial production, etc. It is expected that its second and third phases will promote 8-inch mass production. Dongguan Tianyu is also preparing for the epitaxial growth of 8-inch silicon carbide wafers. However, the overall process still lags behind international advanced enterprises.
He Weiwei pointed out that silicon carbide devices are still out of stock in the market at present. Domestic and foreign silicon carbide enterprises should have a large number of orders in their hands. In the short to medium term, the price of 8-inch wafers per chip will not be much cheaper than that of 6-inch wafers, so it will not bring too much competitive pressure. However, from a medium to long-term perspective, when the relevant processing technology for 8-inch silicon carbide in the international market is fully mature and costs are reduced, China's silicon carbide products, which mainly consist of 6-inch silicon carbide, will face greater competitive pressure, reflected in chip costs, prices, and supply capacity. Therefore, to address such challenges, domestic device manufacturers should actively cooperate with raw material manufacturers such as substrates and epitaxy, fully integrate domestic industry chain enterprises, and jointly develop 8-inch materials, processes, and other technologies, including reducing chip conduction resistance and chip area, and improving single wafer output. Simultaneously integrating the domestic supply chain, utilizing the price and production capacity advantages of domestic substrate epitaxial materials, reducing costs and improving output, comprehensively enhancing core competitiveness in multiple dimensions such as research and development, technology, process, quality, and industrialization.
