Method for making semi-insulating substrate by post-process heating of oxygenated and doped silicon

Claim 1

A method of making a semi-insulating silicon substrate for semiconductor elements comprising, (a) forming an oxygenated, doped single crystal silicon wafer substrate having opposite major surfaces and having semiconductor electrical conductivity, (b) fabricating a semiconductor device on a surface of the substrate by creating a plurality of localized regions in said surface opposite in polarity to adjacent surface regions, thereby forming p-n junctions, the p-n junctions being separated from each other for electrical isolation, said device having high conductivity regions, (c) heating the fabricated semiconductor device and substrate to a temperature of between 300° C. and 500° C. until the substrate under the device is substantially electrically non-conductive.

Claim 2

A method of making a semi-insulating silicon substrate for semiconductor elements comprising, (a) forming an oxygenated, doped single crystal silicon wafer substrate having opposite major surfaces and having semiconductor electrical conductivity, (b) fabricating a semiconductor device on a surface of the substrate by creating a plurality of localized regions in said surface opposite in polarity to adjacent surface regions, thereby forming p-n junctions, the p-n junctions being separated from each other for electrical isolation, said device having high conductivity regions, (c) heating the fabricated semiconductor device and substrate to a temperature of between 300° C. and 500° C. until the substrate under the device is substantially electrically non-conductive.

Claim 8

A method of making a semi-insulating silicon substrate for semiconductor elements comprising, (a) forming an oxygenated, doped single crystal silicon wafer substrate having opposite major surfaces and having semiconductor electrical conductivity, (b) fabricating a semiconductor device on a surface of the substrate by creating a plurality of localized regions in said surface opposite in polarity to adjacent surface regions, thereby forming p-n junctions, the p-n junctions being separated from each other for electrical isolation, said device having high conductivity regions, (c) heating the fabricated device and substrate at least until the p- or n-conductivity type of the substrate under the device changes from one conductivity type to the other.

Claim 9

A method of making a semi-insulating silicon substrate for semiconductor elements comprising, (a) forming an oxygenated, doped single crystal silicon wafer substrate having opposite major surfaces and having semiconductor electrical conductivity, (b) fabricating a semiconductor device on a surface of the substrate by creating a plurality of localized regions in said surface opposite in polarity to adjacent surface regions, thereby forming p-n junctions, the p-n junctions being separated from each other for electrical isolation, said device having high conductivity regions, (c) heating the fabricated device and substrate at least until the p- or n-conductivity type of the substrate under the device changes from one conductivity type to the other.

Claim 12

A method of making a semi-insulating silicon substrate for semiconductor elements comprising: (a) forming an oxygenated single crystal silicon wafer substrate having opposite major surfaces, (b) lightly doping the substrate with a dopant producing an excess of holes of generally uniform, known concentration of between 10 13 to 10 16 per cubic centimeter, at 27° C., thereby forming a semiconductor substrate, (c) fabricating a semiconductor device on the surface of the substrate by creating a plurality of localized regions in said surface opposite in polarity to adjacent surface regions, thereby forming p-n junctions, the p-n junctions being separated from each other for electrical isolation, said device having heavily doped conductive regions, at least some of which are proximate to the substrate, (d) heating the fabricated semiconductor device and substrate to a temperature of between 300° C. and 500° C. until said excess of holes in the substrate is neutralized by oxygen ions to the extent that resistivity of the substrate, under the device has been increased by at least three orders of magnitude, said device having said electrically conductive regions in the substrate surrounded by substantially non-conductive regions.

Claim 13

A method of making a semi-insulating silicon substrate for semiconductor elements comprising: (a) forming an oxygenated single crystal silicon wafer substrate having opposite major surfaces, (b) lightly doping the substrate with a dopant producing an excess of holes of generally uniform, known concentration of between 10 13 to 10 16 per cubic centimeter, at 27° C., thereby forming a semiconductor substrate, (c) fabricating a semiconductor device on the surface of the substrate by creating a plurality of localized regions in said surface opposite in polarity to adjacent surface regions, thereby forming p-n junctions, the p-n junctions being separated from each other for electrical isolation, said device having heavily doped conductive regions, at least some of which are proximate to the substrate, (d) heating the fabricated semiconductor device and substrate to a temperature of between 300° C. and 500° C. until said excess of holes in the substrate is neutralized by oxygen ions to the extent that resistivity of the substrate, under the device has been increased by at least three orders of magnitude, said device having said electrically conductive regions in the substrate surrounded by substantially non-conductive regions.