Silicon carbide crystal growth process and equipment technology

1. SiC crystal growth technology route

PVT (sublimation method),

HTCVD (high temperature CVD),

LPE (liquid phase method)

are three common SiC crystal growth methods;

The most recognized method in the industry is the PVT method, and more than 95% of SiC single crystals are grown by the PVT method;

Industrialized SiC crystal growth furnace uses the industry’s mainstream PVT technology route.

2. SiC crystal growth process

Powder synthesis-seed crystal treatment-crystal growth-ingot annealing-wafer processing.

3. PVT method to grow SiC crystals

The SiC raw material is placed at the bottom of the graphite crucible, and the SiC seed crystal is at the top of the graphite crucible. By adjusting the insulation, the temperature at the SiC raw material is higher and the temperature at the seed crystal is lower. The SiC raw material at high temperature sublimates and decomposes into gas phase substances, which are transported to the seed crystal with lower temperature and crystallize to form SiC crystals. The basic growth process includes three processes: decomposition and sublimation of raw materials, mass transfer, and crystallization on seed crystals.

Decomposition and sublimation of raw materials:

SiC(S)= Si(g)+C(S)

2SiC(S)= Si(g)+ SiC2(g)

2SiC(S)=C(S)+SiC2(g)

During mass transfer, Si vapor further reacts with the graphite crucible wall to form SiC2 and Si2C:

Si(g)+2C(S) =SiC2(g)

2Si(g) +C(S)=Si2C(g)

On the surface of the seed crystal, the three gas phases grow through the following two formulas to generate silicon carbide crystals:

SiC2_(g) +Si2C_(g) =3SiC_(s)

Si_(g) +SiC2_(g)=2SiC_(S)

4. PVT method to grow SiC crystal growth equipment technology route

At present, induction heating is a common technology route for PVT method SiC crystal growth furnaces;

Coil external induction heating and graphite resistance heating are the development direction of SiC crystal growth furnaces.

5. 8-inch SiC induction heating growth furnace

(1) Heating the graphite crucible heating element through magnetic field induction; regulating the temperature field by adjusting the heating power, coil position, and insulation structure;

(2) Heating the graphite crucible through graphite resistance heating and thermal radiation conduction; controlling the temperature field by adjusting the current of the graphite heater, the structure of the heater, and the zone current control;

6. Comparison of induction heating and resistance heating