One expansion technology, from 6 inches straight to 8 inches!
Wolfspeed, Rohm, and II-VI all demonstrated 8-inch silicon carbide substrates in 2015, of which Wolfspeed invested 1 billion US dollars to build a new factory and began to produce 8-inch silicon carbide and other products in April this year; Infineon In September 2020, it announced that its 8-inch SiC wafer production line has been completed; Rohm's SiCrystal company is expected to start mass production of 8-inch substrates around 2023; Soitec released 8-inch silicon carbide substrate products in May 2022, and its It is also launching a new fab construction program in March 2022.
Domestically and internationally, the gap is more obvious on 8-inch silicon carbide substrates.
The first technical difficulty of the silicon carbide 8-inch substrate is the seed crystal. Although the seed crystal can be made by laser cutting and then splicing, the defects at the splicing position are almost difficult to remove. It can be used for basic research on crystal growth. It won't work if you give birth. The seed crystals for mass production still need to be expanded slowly. During the process of expansion, good quality crystals are reserved for optimal propagation. This process is very time-consuming. Without good seed crystals, it is impossible to reproduce good crystals. Just as good crops cannot grow without good seeds. Usually, the diameter is expanded by a few millimeters at a time, and the expansion time from 6 inches to 8 inches is even in units of years.
HIPER Technology provides an innovative solution, expanding the technical direction from 6 inches to 8 inches at one time, providing a new idea for the industry, and promoting the international competitiveness of the domestic industry's 8-inch silicon carbide substrate.
HIPER Technology grows crystals at an angle of ≤45° to crystal ingots with a thickness of ≥30mm and a unilateral diameter expansion of ≥25mm. In this way, the crystal diameter can be expanded to ≥50mm at one time, and the technical route of one-time expansion from 150mm to 200mm can be realized.
At present, HIPER Technology has a unilateral expansion diameter of ≥20mm, no polymorphism, microtubes ≤0.05ea/cm2, growth rate ≥0.3mm/h, and no TaC coating on the diversion ring; it is expected to reach unilateral 25~30mm in the near future, and Optimize face shape.
The core technical difficulties of diameter expansion are: temperature control of thermal field, edge polycrystalline, material flow transmission (gas phase transport)
HIPER Technology uses the temperature control technology mastered for many years to adjust the temperature of the thermal field to a temperature gradient that is conducive to crystal diameter expansion, and adjust it.
Gas phase composition is one of the main causes of edge polycrystals, unreasonable gas phase composition is very easy to produce edge polycrystals, which leads to diameter expansion failure.
Same as crystal growth, material flow is also crucial to diameter expansion. A specially improved [new process] thermal field is used to make gas phase storage and transportation meet diameter expansion.
Actual diagram of crystal diameter expansion:
HIPER Technology | Zero Laboratory is dedicated to the basic research of materials and the exploration of innovative directions.