One hundred millimeter SiC crystal grown on off-axis seed
View Patent ↗A semiconductor crystal and associated growth method are disclosed. The crystal includes a seed portion and a growth portion on the seed portion. The seed portion and the growth portion form a substantially right cylindrical single crystal of silicon carbide. A seed face defines an interface between the growth portion and the seed portion, with the seed face being substantially parallel to the bases of the right cylindrical crystal and being off-axis with respect to a basal plane of the single crystal. The growth portion replicates the polytype of the seed portion and the growth portion has a diameter of at least about 100 mm.
1. An off-axis single crystal silicon carbide wafer made by a method of:
cutting a seed crystal of silicon carbide from a bulk single crystal of silicon carbide at an angle with respect to the c-axis of the bulk crystal to produce a seed crystal with a seed face that is off-axis with respect to the c-face of the bulk crystal;
applying a thermal gradient to the seed crystal in a seeded growth system in a direction that is perpendicular to the seed face of the seed crystal and non-perpendicular with respect to the c-face of the seed crystal to produce a right cylindrical crystal that is between 0.5° and 12° of axis with respect to the c-face and that is at least 100 mm in diameter; and
cutting the off-axis single crystal silicon carbide wafer from the right cylindrical crystal by cutting the right cylindrical crystal perpendicular to the right cylindrical crystal to produce the off-axis single crystal silicon carbide wafer;
wherein the off-axis single crystal silicon carbide wafer has circular, substantially parallel faces that are between about 0.5° and 12° off-axis with respect to a {0001} plane and that have at least a 100 millimeter diameter, a circumferential edge that is perpendicular to the circular, substantially parallel faces, a surface micropipe density between 1 cm −2 and 100 cm −2 , a dopant, and less than two edge chips.
2. The off-axis, single crystal, silicon carbide wafer according to claim 1 having a polytype selected from the group consisting of the 2H, 3C, 4H, 6H and 15R polytypes of silicon carbide.
3. The off-axis, single crystal, silicon carbide wafer according to claim 1 wherein a polytype is selected from the group consisting of 4H and 6H.
4. The off-axis, single crystal, silicon carbide wafer according to claim 1 wherein said face is off-axis towards <11 2 0>.
5. The off-axis, single crystal, silicon carbide wafer according to claim 1 wherein said face is off-axis towards <10 1 0>.
6. The off-axis, single crystal, silicon carbide wafer according to claim 1 further comprising at least one epitaxial layer of semiconductor material.
7. The off-axis, single crystal, silicon carbide wafer according to claim 6 wherein said epitaxial layer comprises silicon carbide.
8. The off-axis, single crystal, silicon carbide wafer according to claim 6 wherein said epitaxial layer comprises a Group III nitride.
9. The off-axis, single crystal, silicon carbide wafer according to claim 6 comprising a plurality of epitaxial layers.
10. The off-axis, single crystal, silicon carbide wafer according to claim 1 having a surface micropipe density of less than 20 cm −2 .
11. The off-axis, single crystal, silicon carbide wafer according to claim 10 having a surface micropipe density of less than 5 cm −2 .