Methods for manufacturing trench MOSFET with implanted drift region
First Claim
1. A method for manufacturing a trenched semiconductor power device comprising plurality of trenched gates surrounded by source regions near a top surface of an epitaxial layer encompassed in body regions, wherein said epitaxial layer is supported on a semiconductor substrate, said method comprising:
- carrying out a tilt-angle implantation through sidewalls of trenches to form drift regions surrounding said trenches to provide drift regions below body regions and above said epitaxial layer for on-resistance reduction, and preventing a degraded breakdown voltage with a thicker oxide along a lower portion of trench sidewall and bottom wherein the thicker oxide having a greater thickness than an oxide layer along an upper portion of said trench sidewalls, and wherein the trenches have trench bottoms disposed below said drift regions extended downwardly to said epitaxial layer.
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Abstract
A method to manufacture a trenched semiconductor power device including a plurality of trenched gates surrounded by source regions near a top surface of a semiconductor substrate encompassed in body regions. The method for manufacturing the trenched semiconductor power device includes a step of carrying out a tilt-angle implantation through sidewalls of trenches to form drift regions surrounding the trenches at a lower portion of the body regions with higher doping concentration than the epi layer for Rds reduction, and preventing a degraded breakdown voltage due to a thick oxide in lower portion of trench sidewall and bottom. In an exemplary embodiment, the step of carrying out the tilt-angle implantation through the sidewalls of the trenches further includes a step of carrying out a tilt angle implantation with a tilt-angle ranging between 4 to 30 degrees.
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Citations
11 Claims
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1. A method for manufacturing a trenched semiconductor power device comprising plurality of trenched gates surrounded by source regions near a top surface of an epitaxial layer encompassed in body regions, wherein said epitaxial layer is supported on a semiconductor substrate, said method comprising:
carrying out a tilt-angle implantation through sidewalls of trenches to form drift regions surrounding said trenches to provide drift regions below body regions and above said epitaxial layer for on-resistance reduction, and preventing a degraded breakdown voltage with a thicker oxide along a lower portion of trench sidewall and bottom wherein the thicker oxide having a greater thickness than an oxide layer along an upper portion of said trench sidewalls, and wherein the trenches have trench bottoms disposed below said drift regions extended downwardly to said epitaxial layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
Specification