Methods of forming semiconductor switching devices having trench-gate electrodes
First Claim
1. A method of forming a semiconductor switching device, comprising the steps of:
- forming a base region in a semiconductor substrate by implanting base region dopants of second conductivity type into the semiconductor substrate;
forming a trench in the semiconductor substrate;
forming a gate electrode which extends opposite the base region, in the trench;
thenimplanting dopants of first conductivity type into the gate electrode and the base region simultaneously; and
forming a thermal oxide layer on the semiconductor substrate, while simultaneously diffusing the implanted dopants of first conductivity type into the base region to define a source region therein.
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Abstract
Methods of forming semiconductor switching devices having trench-gate electrodes include the steps of implanting base region dopants of second conductivity type into a semiconductor substrate to define a preliminary base region therein. A step is then performed to form a trench having sidewalls which extend through the preliminary base region. A sacrificial insulating layer is then formed on the sidewalls of the trench while the implanted base region dopants are simultaneously diffused into the region of first conductivity type. The sacrificial insulating layer is then removed. Next, a gate electrode insulating layer is formed on the sidewalls and on a bottom of the trench. A gate electrode is then formed on the gate electrode insulating layer. Dopants of first conductivity type are then implanted into the semiconductor substrate to define a preliminary source region, which forms a P-N junction with the implanted base region dopants, and into the gate electrode to improve the conductivity thereof. Then a thermal oxide layer is formed on the semiconductor substrate, while the implanted dopants of second and first conductivity type are diffused into the semiconductor substrate. A BPSG layer may also be deposited and reflowed. These latter steps may be utilized to accurately define the depth of the source region and the length of the channel regions extending along the sidewalls of the trenches. Preferred electrical characteristics can therefore be achieved through careful and essentially independent control of the depth/profile of the base region and the depth/profile of the source region.
101 Citations
16 Claims
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1. A method of forming a semiconductor switching device, comprising the steps of:
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forming a base region in a semiconductor substrate by implanting base region dopants of second conductivity type into the semiconductor substrate; forming a trench in the semiconductor substrate; forming a gate electrode which extends opposite the base region, in the trench;
thenimplanting dopants of first conductivity type into the gate electrode and the base region simultaneously; and forming a thermal oxide layer on the semiconductor substrate, while simultaneously diffusing the implanted dopants of first conductivity type into the base region to define a source region therein. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of forming a semiconductor switching device, comprising the steps of:
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forming a first insulating layer on a face of a semiconductor substrate containing a region of first conductivity type therein extending to the face; implanting dopants of second conductivity type through the first insulating layer and into the region of first conductivity type to define a preliminary base region therein extending to the face; forming a trench having sidewalls which extend through the preliminary base region and into the region of first conductivity type, at the face of the semiconductor substrate; forming a sacrificial insulating layer on the sidewalls of the trench while simultaneously diffusing the implanted dopants of second conductivity type into the region of first conductivity type; removing the sacrificial insulating layer and first insulating layer;
thenforming a gate electrode insulating layer on the sidewalls and a bottom of the trench; forming a gate electrode on the gate electrode insulating layer; implanting dopants of first conductivity type into the semiconductor substrate to define a preliminary source region, which forms a P-N junction with the implanted dopants of second conductivity type, while simultaneously implanting dopants of first conductivity type into the gate electrode; and forming a thermal oxide layer on the semiconductor substrate while simultaneously diffusing the implanted dopants of second and first conductivity type into the semiconductor substrate to define a base region of second conductivity type and a source region of first conductivity type in the base region. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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Specification