SBIR-STTR Award

We propose to use a gas fed vertical style sublimation reactor that can accomodate several different types of chemistries and be modified to a number of different approaches. The reactor is similar to the HTCVD reactor developed by Linkping University and Okmetic. The approach will be to initially try out different chemistries at fairly high temperatures where sublimation is a dominant process. By studying the gas phase nucleation a high degree of understanding can be derived and a moderate temperature process can be developed. Using the knowledge from these experiments and from similar experiments conducted in a CVD reactor, a low temperature CVD approach will be developed with no thermal gradient. It is believed that a growth rate of at least 300 micrometer/h can be achieved at modest temperatures around 1500 - 1600C using the correct chemistry. The main issue is to be able to transport the material to the wafer with a minimum of parasitic processes and deposit the material on the wafer in a uniform and orderly fashion. The level of success is greatly increased since both a sublimation approach and a CVD approach will be tried and compared against each other.

Benefit:
The bulk growth of SiC is hampered by small sizes and poor quality. The quality is slowly improving, but it is of great importance to quickly develop 4-inch and 150 mm diameter SiC wafers of high quality to make use of the standard processing tools. This program is geared towards developing a cost efficient way of growing high quality wafers that may be used for power device applications and high frequency applications. It is believed that after the phase II effort, 150 mm wafer material of such high quality can be made that the wafer itself is the active layer of a (20 - 30 kV) power device. Semi insulating wafers can be grown at a low cost that display essentially no trapping and that has high thermal conductivity. Both of these properties and the cost of manufactrure are of crucial importance to the high frequency industry.

Keywords:
halo-hydrocarbons, halo-hydrocarbons, HTCVD, Sublimation, high growth rates, cvd, Low temperature bulk growth, high purity and high crystalline quality, silane and chlorinated silanes.

We propose to use a gas fed vertical style sublimation reactor that can accommodate several different types of chemistries and be modified to a number of different approaches. The reactor is similar to the HTCVD reactor developed by Linkping University and Okmetic. The approach will be to initially try out different chemistries at fairly high temperatures where sublimation is a dominant process. By studying the gas phase nucleation a high degree of understanding can be derived and a moderate temperature process can be developed. Using the knowledge from these experiments and from similar experiments conducted in a CVD reactor, a low temperature CVD approach will be developed with no thermal gradient. It is believed that a growth rate of at least 1mm/h can be achieved at modest temperatures around 1900C using the correct chemistry. The main issue is to be able to transport the material to the wafer with a minimum of parasitic processes and deposit the material on the wafer in a uniform and orderly fashion. The level of success is greatly increased since both a sublimation approach and a CVD approach will be tried and compared against each other. The bulk growth of SiC is hampered by small sizes and poor quality. The quality is slowly improving, but it is of great importance to quickly develop 4-inch and 150 mm diameter SiC wafers of high quality to make use of the standard processing tools. This program is geared towards developing a cost efficient way of growing high quality wafers that may be used for power device applications and high frequency applications. It is believed that after the phase II effort, high quality crystals can be grown at low temperatures suitable for both power devices and high frequency devices. The cost of manufacture will be reduced thanks to the lower temperature and the higher quality material.

Benefit:
Larger diameter SiC wafers, Lower Cost, Higher Purity, Reduced Micropipes, and Longer Boule Lenghts,

Keywords:
Low temperature bulk growth, cvd, Sublimation, high growth rates, Cougar, high purity and high crystalline quality, halo-hydrocarbons