The use of silicon carbide (SiC) semiconductors offers a huge advantage for electric vehicles (EVs) due to lower switching losses and higher efficiencies, but cost has always been a drawback. SiC wafer manufacturing can suffer from high costs and lower yields, causing SiC semiconductors to cost up to eight times more than their silicon equivalents. This cost often gets passed on to the end customer, making EVs more expensive.
Right now, SiC chipmakers are trying to solve the yield problem by moving to an eight-inch wafer diameter. While this would increase capacity, the manufacturing challenges haven’t gone away. SiC remains a hard, brittle material that requires high heat for processing. That’s why Entegris is working with SiC manufacturers on every process from crystal growth to device manufacturing to help improve cost, quality, and throughput.
Why Increase SiC Wafer Sizes?
SiC crystals are hard enough to grow and process as is. Why borrow trouble by trying to grow them larger?
Part of the reason for moving to an eight-inch wafer diameter is directly related to the difficulty of crystal growth. Not only does it take much longer to grow SiC crystals – days instead of hours – manufacturers can only obtain 40-50 wafers per boule.
By expanding SiC wafers horizontally, SiC manufacturers can potentially increase their yields. A larger surface area results in more chips per wafer. In addition, growing a larger diameter crystal doesn’t significantly increase time and cost compared to growing one that’s taller.
Infrastructure is another reason for moving to a larger wafer size. Manufacturing and processing six-inch diameter SiC wafers requires dedicated equipment. Meanwhile, there are traditional silicon semiconductor fabs sitting with excess capacity available due to lower demand in the eight-inch form factor. When it comes to scaling SiC production, it’s a lot easier to retrofit existing facilities than it is to make new ones.
Challenges of an Increased SiC Wafer Diameter
SiC is a difficult material to work with. The material is both hard and brittle, which means that growing, handling, and processing SiC ingots can be extremely difficult. Defects and product loss are extremely common. This adds to the cost of creating crystals and wafers.
Another part of the cost is related to the price of consumables. A single graphite consumable part for the SiC epitaxy process might cost several thousands of dollars while lasting only three or four production cycles. That’s because wafer growth and epitaxy take place at extremely high temperatures, which can lead to added wear and tear on equipment.
The high temperatures present another concern – contamination. Some consumables may begin off-gassing or producing volatiles under extreme conditions. This can poison the SiC crystal or wafer, rendering it useless. To avoid this outcome, many chipmakers are working with Entegris to obtain market-leading materials that are specifically tailored for high-volume SiC production.
Materials Science and Materials Purity Enable Larger SiC Wafer Diameters
Entegris is delivering purity and longevity to help SiC chipmakers successfully master the transition to eight-inch wafers. Our consumables – such as furnace liners and epitaxy rings – last for more production cycles and are at lower risk of contaminating valuable crystals and wafers. Entegris is also the market leader when it comes SiC consumables for chemical mechanical planarization (CMP). Our slurries, pads, and cleans are proven to increase wafer output and yields. For chipmakers, this means lower costs and improved quality.
Entegris has decades of experience creating high purity synthetic graphite. Because of the high degree of purity – much higher than that of graphite produced from natural sources – we can negate contamination risks during high-temperature processes. In addition, we can create graphite to highly controlled specifications, which means that it can deliver better mechanical performance. In practice, this results in products, such as SiC epitaxy rings, that last four times longer under extreme conditions.
Entegris’ CMP solutions are also designed to increase throughput while reducing defectivity. We’ve recently introduced a high removal rate SiC slurry which can overcome the material’s hardness at a rate of 10-12 µm/h. Because the slurry particles are engineered to remove material without excess scratching or defectivity, chipmakers can enjoy dramatic improvements in terms of productivity without sacrificing yield.
By offering high-purity, longer-lasting materials, Entegris gives SiC chipmakers the opportunity to reduce their production costs and then pass those savings on to the end-customer. The ultimate goal is to reduce the cost of SiC devices until they trigger widespread adoption. In the future, we may see the SiC ecosystem spread to many more automotive and EV components – unlocking even longer ranges, faster charging times, and an economy less dependent on fossil fuels.
Learn more about our complete solutions for SiC wafers.
