Patent ID: 7192872

Claim:
A method for manufacturing a semiconductor device with composite buffer layer, which comprises the steps of: covering a first semiconductor wafer of a first conductivity type with a first mask of a first pattern, wherein the first mask of the first pattern makes some portions of the surface of the semiconductor wafer be covered by the first mask while the other portions are not covered; etching the portions of the semiconductor wafer uncovered by the mask, so as to form first mosaic grooves of first depth, which have bottoms and sidewalls; forming a thin dielectric layer on the sidewall of the groove, and/or a thin dielectric layer on the bottom of the groove, and/or a thin dielectric layer on the surface of the first semiconductor wafer outside the groove, on the first semiconductor wafer having the first mosaic grooves; covering a second semiconductor wafer of a second conductivity type with a second mask of a second pattern, wherein the second mask of the second pattern makes the portions of the second semiconductor wafer covered by the second mask be identical with the pattern formed by the bottoms of the grooves of the first semiconductor wafer; etching the portions of the second semiconductor wafer uncovered by the second mask, so as to form second mosaic grooves which have bottoms, sidewalls, and depths approaching the first depth; forming a thin dielectric layer on the sidewall of the groove, and/or a thin dielectric layer on the bottom of the groove, and/or a thin dielectric layer on the surface of the first semiconductor wafer outside the groove, on the second semiconductor wafer having the second mosaic grooves; bonding the surface outside the grooves of the second semiconductor wafer with the bottoms of the grooves of the first semiconductor wafer, bonding the bottoms of the grooves of the second semiconductor wafer with the surface outside the grooves of the first semiconductor wafer, and bonding the sidewalls of the grooves of the first semiconductor wafer with the sidewalls of the grooves of the second semiconductor, so that the two wafers are bonded as one semiconductor wafer; and forming the composite buffer layer within the first depth in the bonded semiconductor wafer.