Chemical vapor deposition (CVD) of cubic silicon carbide SiC

Abstract

A method for chemical vapor deposition (CVD) of cubic Silicon Carbide (SiC) comprising the steps of etching silicon substrates having one mechanically polished face; depositing a thin buffer layer of cubic SiC formed by reaction between a heated Si substrate and a H 2 C 3 H 8 gas mixture; and depositing SiC on the buffer layer at high temperature using H 2 +C 3 H 8 +SiH 4 mixture.

What is claimed as new and desired to be secured by Letters Patent of the United States is: 
     
       1. A method for producing large-area cubic SiC wafers comprising the steps of: wet-etching an Si substrate;   heating the Si substrate to between 1370° C. and 1405° C. in H 2  gas;   exposing the Si substrate to C 3  H 8  for 5-30 seconds, after temperature equilibrium in the heating step has been reached, to form a buffer layer of single crystal cubic SiC on the Si substrate, the amount of C 3  H 8  being no greater than 1% by volume of the H 2  gas;   quenching to room temperature the Si substrate having a cubic SiC buffer layer in a gas of H 2  ;   heating the Si substrate with the SiC buffer layer to between 1370° C. and 1405° C. in H 2  gas;   exposing the Si substrate having the buffer layer to C 3  H 8  and SiH 4  after thermal equilibrium has been reached in the second heating step for 0.25 to 5 hours to make a thicker layer of cubic SiC, the amount of C 3  H 8  and SiH 4  each being no greater than 1% by volume of the H 2  gas; and   quenching the Si substrate having the thicker layer of SiC in H 2  gas to room temperature.   
     
     
       2. A method as described in claim 1 wherein the wet-etching step is carried out in a mixture of nitric, hydrofluoric and acetic acid in a volume ratio of 5:3:3, respectively. 
     
     
       3. A method as described in claim 2 wherein after the wet-etching step, there is an additional step of placing the wet-etched Si substrate on a graphite susceptor inside an rf-induction heated quartz tube.