Silicon carbide: An exclusive: semiconductors on the move to mainstream

Silicon carbide: The five-star semiconductor

Silicon carbide (SiC) is used in applications that require high-performance chips with faster speed, higher voltages, and less power consumption. For example, electric vehicles must process high voltages at minimum power loss to achieve higher mileage. Or imagine how the performance of power converters in renewable solar and wind energy systems affects the efficiency of electric energy generation. Every kilowatt of energy saved on the power conversion helps to mitigate climate change. SiC is like the Rolls-Royce of semiconductors because it has a large bandgap and excellent electron mobility. Therefore, SiC chips can operate at higher temperatures, voltages, and frequencies, providing a substantial boost in performance and efficiency. The increased thermal conductivity keeps SiC chips cool all the time.

With high performance comes high cost and a more demanding manufacturing process. At present, SiC chips are significantly more expensive in production. Therefore, they are only used in cases where the higher costs are worth it. “Producing high-quality, large-diameter SiC wafers as a starting material for chip production is already a very complex vacuum process, called the Lely method,” explains Theresa Tang, Industry Sector Manager at VAT. “A powder of SiC is melted and evaporated under an inert atmosphere and a slight vacuum to deposit from the gas phase on a seed crystal over a period of one to two weeks.”

Vacuum technology is crucial for the production of high quality SiC substrate. VAT has been working alongside its customers throughout the evolution of SiC-growing technologies, from crystal pulling to the currently most-used CVD, to the cutting-edge epitaxy process. Butterfly valves series 61.6 and 61.3 allow very precise process control and timing. Isolation valves S10, S19, and S12 offer a flexible selection to suit OEMs’ design and cost demands. With performance capacities exceeding current requirements, VAT is ready to facilitate the next developments in technology.

VAT vacuum expertise improves SiC production process efficiency

To tackle these challenges, furnace manufacturers are taking a deeper look into the process stability of SiC crystal growth to reduce failure rates and increase yields. One component often overlooked is the vacuum system. This includes pressure stability as well as the level of contamination in the vacuum atmosphere. Similar to distilling alcohol, it is especially important to separate growth steps from thermal and chemical preconditioning steps for substrate, source material, and system purification in SiC crystal growths. Also, the pressure set during the SiC wafer growth has a significant impact on the evaporation and deposition rates during the process. For this reason, it is crucial to control and set the pressure in the furnace very accurately. VAT has a wide product range to enable accurate vacuum control in SiC processes.

“Our VAT 61.6 series control valve is our workhorse for accurate process control in vacuum applications. It is used by many industries and scientists requiring high reproducibility and accuracy. When we presented it to SiC furnace manufacturers, they were delighted with its performance,” says Theresa Thang. Indeed, the performance is outstanding: The 61.6 control valve can control the pressure with a stability of 0.1% of the setpoint at an actuation speed of less than 0.38s. This performance is supplemented by a contamination-free Viton sealing that can provide a leak-free closure with almost no wear. “With a cycle lifetime of 250,000, furnace customers will probably never need to maintain the valve sealings, and can keep their crystal growth running without readjustment or verification of process parameters due to valve maintenance,” says Theresa Thang, outlining the advantages of the 61.6 control valve.

Spreading SiC chips for a sustainable economy with VAT technology

Based on the success with the control valves in the SiC market, VAT is now even supplying more valve types to SiC furnace manufacturers, e.g., the 12.1 gate valve to separate the pumps from the furnace, or our 26.4 angle valve series. “What sets us apart is our application-oriented approach of finding the right solution for our customer’s processes, rather than supplying valves off-the-shelf,” says Theresa Thang, discussing the success of VAT in the industry.

Our climate and planet rely on more and cheaper electric vehicles, better power conversion from renewable energies, and less power consumption in electronic devices. While SiC chip production is still in its infancy compared to silicon, innovative furnace manufacturers, supported by high-technology providers like VAT, are taking the next steps to close the gap by improving processes and yields to reduce SiC production costs. VAT is a proud partner of this fast-growing and climate-relevant industry to enable the utilization of more efficient SiC chips on a larger scale.