Patent ID: 7902053
Filing Date: 2011-03-08
Classification: H01L

Abstract:
1. A method of processing a semiconductor wafer, comprising: providing a semiconductor wafer of a first general conductivity type; growing a first epitaxial semiconductor layer of the first general conductivity type only from the semiconductor wafer; etching the first epitaxial semiconductor layer to form a plurality of trenches; growing a second epitaxial semiconductor layer of a second general conductivity type from the etched first epitaxial semiconductor layer so as to leave a void in each trench; etching the second epitaxial semiconductor layer so as to expose a top surface of the first epitaxial semiconductor layer; growing a third epitaxial semiconductor layer of the first general conductivity type from the exposed top surface of the first epitaxial semiconductor layer and the etched second epitaxial semiconductor layer in the trenches so that the voids are filled at least partially with the third epitaxial semiconductor layer; and etching the third epitaxial semiconductor layer so as to expose the top surface of the first epitaxial semiconductor layer and a top surface of the second epitaxial semiconductor layer, wherein the first epitaxial semiconductor layer has substantially the same impurity concentration as the third epitaxial semiconductor layer.