Method of manufacturing substrates having improved carrier lifetimes
View Patent ↗This invention relates to a method for depositing silicon carbide material onto a substrate such that the resulting substrate has a carrier lifetime of 0.5-1000 microseconds, the method comprising a. introducing a gas mixture comprising a chlorosilane gas, a carbon-containing gas, and hydrogen gas into a reaction chamber containing a substrate; and b. heating the substrate to a temperature of greater than 1000° C. but less than 2000° C.; with the proviso that the pressure within the reaction chamber is maintained in the range of 0.1 to 760 torr. This invention also relates to a method for depositing silicon carbide material onto a substrate such that the resulting substrate has a carrier lifetime of 0.5-1000 microseconds, the method comprising a. introducing a gas mixture comprising a non-chlorinated silicon-containing gas, hydrogen chloride, a carbon-containing gas, and hydrogen gas into a reaction chamber containing a substrate; and b. heating the substrate to a temperature of greater than 1000° C. but less than 2000° C.; with the proviso that the pressure within the reaction chamber is maintained in the range of 0.1 to 760 torr.
1. A method for depositing silicon carbide coating onto a single crystal silicon carbide substrate such that the resulting coating has a carrier lifetime of 0.5-1000 microseconds, the method comprising
a. continuously introducing a controlled amount of a gas mixture comprising a chlorosilane gas, wherein the chlorosilane gas is dichlorosilane gas, methylhydrogendichlorosilane gas, dimethyldichlorosilane gas, or mixtures thereof, a carbon-containing gas, and hydrogen gas into one portion of a reaction chamber containing a 4H single crystal silicon carbide substrate having an angle of tilt of 4 to 8 degrees while drawing a vacuum from another site in the reaction chamber so as to cause flow of the vapor to be uniform over the area of the substrate;
b. heating the substrate to a temperature of greater than 1200° C. but less than 1800° C.; with the proviso that the pressure within the reaction chamber is maintained in the range of 10 to 250 torr, wherein a total gas flow rate is 1-150 liters per minute, and a combined flow rate of the chlorosilane gas and carbon-containing gas is 0.1 to 30% of the total flow rate, wherein the resulting single crystal silicon carbide substrate contains a 4H silicon carbide epitaxial layer having a thickness of 1 nm up to 25 cm.
2. A method according to claim 1 wherein the gas mixture further comprises a doping gas.
3. A method according to claim 2 wherein the doping gas is nitrogen gas, phosphine gas, or trimethylaluminum gas.
4. A method according to claim 1 wherein the carbon-containing gas is C 3 H 8 gas, C 2 H 6 gas, CH 3 Cl gas, or CH 3 CH 2 CH 2 Cl gas.
5. A method according to claim 1 , wherein the angle of tilt is 4 to 8 degrees and tilted to <1120>.
6. A method according to claim 1 , wherein the angle of tilt is 8 degrees and tilted to <1120>.
7. A method according to claim 1 , wherein the substrate is fabricated such that normal to its surface is tilted at an angle relative to the [0001] plane of the SiC of the crystal.
8. A method according to claim 5 , wherein the substrate is fabricated such that normal to its surface is tilted at an angle relative to the [0001] plane of the SiC of the crystal.
9. A method according to claim 6 , wherein the substrate is fabricated such that normal to its surface is tilted at an angle relative to the [0001] plane of the SiC of the crystal.