Method of forming vertical trench-gate semiconductor devices having self-aligned source and body regions
First Claim
1. A method of forming a semiconductor switching device, comprising the steps of:
- patterning an oxidation resistant layer to define an opening therein, on a face of a semiconductor substrate;
forming a trench in the semiconductor substrate, opposite the opening in the oxidation resistant layer;
forming an electrode in the trench;
oxidizing the semiconductor substrate to form electrically insulating regions at a periphery of the patterned oxidation resistant layer, using the patterned oxidation resistant layer as an oxidation mask; and
implanting dopants of first and second conductivity type into the semiconductor substrate to define preliminary source and body regions therein extending adjacent a sidewall of the trench, using the electrically insulating regions as an implant mask.
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Abstract
Methods of forming vertical trench-gate semiconductor devices include the steps of patterning an oxidation resistant layer having an opening therein, on a face of a semiconductor substrate, and then forming a trench in the semiconductor substrate, opposite the opening in the oxidation resistant layer. An insulated gate electrode is then formed in the trench. The face of the semiconductor substrate is then oxidized to define self-aligned electrically insulating regions in the opening and at a periphery of the patterned oxidation resistant layer. Here, the patterned oxidation resistant layer is used as an oxidation mask so that portions of the substrate underlying the oxidation resistant layer are not substantially oxidized. Source and body region dopants of first and second conductivity type, respectively, are then implanted into the substrate to define preliminary source and body regions which extend adjacent a sidewall of the trench. During the implanting step, the electrically insulating regions are used as a self-aligned implant mask. The implanted dopants are then diffused into the substrate to define source and body regions adjacent upper and intermediate portions of the sidewall of the trench, respectively.
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Citations
20 Claims
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1. A method of forming a semiconductor switching device, comprising the steps of:
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patterning an oxidation resistant layer to define an opening therein, on a face of a semiconductor substrate; forming a trench in the semiconductor substrate, opposite the opening in the oxidation resistant layer; forming an electrode in the trench; oxidizing the semiconductor substrate to form electrically insulating regions at a periphery of the patterned oxidation resistant layer, using the patterned oxidation resistant layer as an oxidation mask; and implanting dopants of first and second conductivity type into the semiconductor substrate to define preliminary source and body regions therein extending adjacent a sidewall of the trench, using the electrically insulating regions as an implant mask. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of forming a semiconductor switching device, comprising the steps of:
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forming a first oxide layer on a face of a semiconductor substrate containing a drift region of first conductivity type therein extending to the face; forming a first nitride layer on the first oxide layer, opposite the face; etching the first nitride layer to expose the first oxide layer at a periphery thereof;
thenimplanting dopants of second conductivity type into the drift region to define a preliminary contact region therein, using the first nitride layer as an implant mask;
thenetching the first nitride layer and first oxide layer to define an opening therein exposing the face of the semiconductor substrate; etching the semiconductor substrate at the opening to define a trench therein; forming an insulated gate electrode in the trench; oxidizing the insulated gate electrode and the preliminary contact region to form self-aligned electrically insulating regions therein, using the first nitride layer as an oxidation mask; implanting dopants of first and second conductivity type into the drift region at respective first and second energies to define preliminary source and body regions therein, using the electrically insulating regions as an implant mask; and diffusing the dopants in the preliminary source, body and contact regions into the drift region to define a source region extending adjacent an upper portion of a sidewall of the trench, a body region extending adjacent an intermediate portion of the sidewall of the trench and a contact region forming a non-rectifying junction with the body region at a location spaced from the sidewall of the trench. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification