Patent ID: 6972231
Filing Date: 2005-12-06
Classification: H01L

Abstract:
1. A process for forming graded body diode regions, comprising: selecting a semiconductor substrate having a front surface and a back surface opposite of the front surface, the substrate comprised of silicon doped with a dopant of a first conductivity type; implanting and diffusing channel diffusions in the front surface of the substrate, the channel diffusions being of a second conductivity type having an opposite conductivity to the first conductivity type, the channel diffusions defining spaces between the channel diffusions, the spaces having a conductivity of the first conductivity type; implanting and diffusing enhancement diffusions of the first conductivity type in the spaces, increasing the concentration of the first conductivity type in the spaces; implanting and diffusing second diffusions having opposite conductivity type in the channel diffusions such that the second diffusions overlap the enhancement diffusions, each of the second diffusions defining left and right boundary regions between the portion of the substrate in the channel diffusions having a net conductivity of the second conductivity type and the portion of the substrate in the spaces having a net concentration of the first conductivity type; implanting and diffusing shallow diffusions within the second diffusions, defining a shallow, partially counterdoped region in a portion of the channel diffusions, the net concentration of the counterdoped region remaining the second conductivity type, but having a lower net concentration than surrounding portions of the channel diffusions; and implanting and activating source diffusions of the first conducitivity type in the channel diffusions such that the source diffusions have a net concentration of the first conductivity type surrounding by a region of the channel diffusions having a net concentration of the second conductivity type, wherein graded body diode regions are formed.