SiC crystal growth enters the era of resistance furnaces!
In June 2022, HIPER launched a new generation of SiC resistance crystal growth furnace version 2.0. The furnace type launched in this mass production is a new version based on Hengpu's previous generation of 6-inch and 8-inch resistance furnaces, and actively responds to the market's demand for SiC resistance crystal growth. Furnace industry needs.
Almost all domestic SIC crystal growth furnaces use induction heating. The induction heating crystal growth furnace has low equipment investment, simple structure, convenient maintenance, and high thermal efficiency. It is widely used in the industry. However, there are also some technical difficulties that restrict the further improvement of its performance. The main difficulty is: due to the skin effect, it is difficult to establish a uniform thermal field, and the temperature of the thermal field is easily disturbed by the external environment, which is difficult to correct. internal disturbance, and the process parameters are deeply coupled, making it difficult to control. With the advent of the 8-inch silicon carbide era, as the diameter of the crucible increases, the induction coil can only heat the surface of the crucible, and the radial temperature gradient at different positions will increase accordingly, which is not suitable for large-diameter crystal growth. , for the decomposition of raw materials, the crystal surface type, and the adjustment of complex defects caused by thermal stress, all face challenges.
In order to solve the pain points of the industry, HIPER has launched a SiC crystal growth technology platform with [shaft-diameter separation] as the core technology and graphite heat generation, combined with [new process], a breakthrough solution to crystal growth. 长大、长快、长厚的行业核心需求。
Products and Core Technology A new generation of graphite heating crystal growth furnace actively adjusts the regional temperature in the radial region of the seed crystal, and the axial temperature adjusts the regional temperature through the thermal field of the material region, thereby realizing [axis-diameter separation].
When the crystal grows, as the thickness increases, the heat capacity of the seed crystal area changes, and the thermal conductivity will also change greatly. The changes in these parameters will affect the temperature of the seed crystal area. Since the seed crystal area has a radial plane The heating element can actively adjust the temperature of the radial plane to realize the controllable heat loss of the radial plane. As the raw material decomposes, the thermal conductivity of the material changes (note: the old process of secondary mass transfer), and it will crystallize on the upper part of the material. The thermal field in the material area can actively adjust the temperature of the material area according to the state of the material. When setting the growth process, you only need to directly set the temperature curve of the seed crystal region and the temperature curve of the axial temperature gradient, "what you see is what you get", which reduces the difficulty of process coupling and avoids the process black box.
In order to achieve [shaft-diameter separation], it is necessary to precisely control the temperature, instead of using traditional power control, so the new furnace model is equipped with [temperature closed-loop control] as standard, and the whole crystal growth process adopts temperature control. The perfect combination of [shaft-diameter separation] and [new process] is the technical highlight of the new generation 2.0 version of the SIC resistance crystal growth furnace. Diameter separation] precise regional temperature control technology, more optimized to solve the industry needs of crystal growth, fast growth, and long thickness.
The crystal growth furnace with graphite thermal field heating has some natural advantages: a. temperature stability; b. process repeatability; c. controllability of temperature field. It is more suitable for the growth of large-size silicon carbide SIC crystals, such as: 8 inches or larger.
Some functions of the new technology platform:
【Shaft Diameter Separation】*
【Temperature closed-loop control】*
【High precision pressure control】*
【Full Size (6 inches and 8 inches)】
【Compact thermal field design, greatly reducing energy consumption】
See technical notes below for details:
There is no strong coupling between the axial temperature gradient and the radial temperature, and high-precision control of the axial temperature gradient and radial temperature can be performed separately. It is one of the core technologies to solve crystal growth.
Temp Control at Whole Cycle
SiC crystals grow at high temperatures above 2000°C, which requires extremely high temperature stability. However, due to the volatilization of SiC powder and other reasons, it is impossible to accurately measure the temperature, resulting in the inability to control the temperature during crystal growth. For power control, HIPER adopts an innovative temperature measurement method, which can greatly improve the temperature measurement accuracy and maintain a high degree of stability, and can adopt temperature control in the entire cycle of crystal growth.
Using a new thermal field for primary mass transfer, the mass transfer efficiency is improved and basically constant, reducing the impact of recrystallization (avoiding secondary mass transfer), and effectively reducing micropipes or other crystal defects. In the later stage of growth, the influence of carbon inclusions is reduced, and the crystal thickness is greatly increased under the premise of satisfying the crystal quality. It is one of the core technologies to solve crystal growth and thickness.
High Precision Pressure Control
SiC crystal growth furnace usually controls the fluctuation of pressure at ±3Pa during crystal growth, but HIPER's new technology can control the pressure at ±0.3Pa, which is an order of magnitude higher.