Trench gated power device with multiple trench width and its fabrication process
First Claim
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1. A semiconductor device, comprising:
- a semiconductor mass;
gate electrodes in first trenches in said semiconductor mass, and field plate electrodes in second trenches in said semiconductor mass;
wherein said first trenches and said second trenches have substantially the same depth;
wherein said first and said second trenches each have stepped sides having at least three distinct widths, wherein a top portion of each said trench is wider than a middle portion thereof which has substantially vertical sidewalls, and a bottom portion thereof is narrower than said middle portion;
wherein said first and said second trenches are not identical;
a first-conductivity-type source region, in said semiconductor mass, near said first trenches, and a second-conductivity-type body region adjacent said first trenches, and a second-conductivity-type body contact region surrounding said second trenches.
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Abstract
Power devices, and related process, where both gate and field plate trenches have multiple stepped widths, using self-aligned process steps.
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Citations
20 Claims
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1. A semiconductor device, comprising:
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a semiconductor mass; gate electrodes in first trenches in said semiconductor mass, and field plate electrodes in second trenches in said semiconductor mass; wherein said first trenches and said second trenches have substantially the same depth; wherein said first and said second trenches each have stepped sides having at least three distinct widths, wherein a top portion of each said trench is wider than a middle portion thereof which has substantially vertical sidewalls, and a bottom portion thereof is narrower than said middle portion; wherein said first and said second trenches are not identical; a first-conductivity-type source region, in said semiconductor mass, near said first trenches, and a second-conductivity-type body region adjacent said first trenches, and a second-conductivity-type body contact region surrounding said second trenches. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A semiconductor device, comprising:
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a semiconductor mass; gate electrodes in first trenches in said semiconductor mass, and field plate electrodes in second trenches in said semiconductor mass; wherein said first trenches and said second trenches both extend into a first surface of said semiconductor mass, and all have substantially the same depth; wherein said first and said second trenches each have stepped sides having at least three distinct widths, wherein a top portion of each said trench is wider than a middle portion thereof which has substantially vertical sidewalls, and a bottom portion thereof is narrower than said middle portion; wherein said first and said second trenches are not identical; and wherein said gate electrodes, but not said field plate electrodes, are connected directly to receive a gate drive waveform; a first-conductivity-type source region, in said semiconductor mass, near said first trenches, and a second-conductivity-type body region adjacent said first trenches, and a second-conductivity-type body contact region surrounding and self-aligned to said second trenches; and a first-conductivity-type drain region at a second surface of said semiconductor mass; whereby, in the ON state, voltage applied to said gate electrode controls majority carrier emission from said source, to thereby allow current conduction between said source and said drain; and
whereby said field plate electrodes affect isopotential contours, in the OFF state, to increase the breakdown voltage between said source and said drain. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A semiconductor device, comprising:
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a semiconductor mass; gate electrodes in first trenches in said semiconductor mass, and field plate electrodes in second trenches in said semiconductor mass; wherein said first trenches and said second trenches have substantially the same depth; wherein said first and said second trenches each have stepped sides having at least three distinct widths, wherein a top portion of each said trench is wider than a middle portion thereof which has substantially vertical sidewalls, and a bottom portion thereof is narrower than said middle portion; wherein said first and said second trenches are not identical; a first-conductivity-type source region, in said semiconductor mass, adjacent and self-aligned to said first trenches; a second-conductivity-type body region adjacent said first trenches; a second-conductivity-type body contact region surrounding and self-aligned to said second trenches; and modified regions, below and self-aligned to said second trenches, which have a smaller net concentration of second-conductivity-type dopants than said body region does. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification