Silicon carbide substrate and method of growing SiC single crystal boules
The present invention relates to a silicon carbide (SiC) substrate with improved mechanical and electrical characteristics. Furthermore, the invention relates to a method for producing a bulk SiC crystal in a physical vapor transport growth system. The silicon carbide substrate comprises an inner region ( 102 ) which constitutes at least 30% of a total surface area of said substrate ( 100 ), a ring shaped peripheral region ( 104 ) radially surrounding the inner region ( 102 ), wherein a mean concentration of a dopant in the inner region ( 102 ) differs by at least 1-10 18 cm- 3 from the mean concentration of this dopant in the peripheral region ( 104 ).
1. Silicon carbide substrate, comprising:
a doped inner region ( 102 ) which constitutes 45%±15% of a total surface area of said substrate ( 100 ),
a doped ring shaped peripheral region ( 104 ) radially surrounding the inner region ( 102 ),
wherein a mean concentration of a dopant in the inner region ( 102 ) differs by at least 1.10 18 cm −3 from the mean concentration of this dopant in the peripheral region ( 104 ), and
wherein a bow of the substrate ( 100 ) is less than 25 μm and/or a warp of the substrate ( 100 ) is less than 40 μm.
2. Silicon carbide substrate according to claim 1 , wherein said dopant comprises nitrogen, and wherein the nitrogen dopant concentration is lower in the peripheral region ( 104 ) than in the inner region ( 102 ).
3. Silicon carbide substrate according to claim 1 , wherein the mean concentration of said dopant in the inner region ( 102 ) differs by at least 5.10 18 cm −3 from the mean concentration of this dopant in the peripheral region ( 104 ).
4. Silicon carbide substrate according to claim 1 , wherein the substrate ( 100 ) has an electrical resistivity in a range from 12 mΩ cm to 26 mΩ cm.