Method for fabricating MOSFET having increased effective gate length
First Claim
1. A semiconductor device, having a source, a drain and a gate electrode, fabricated by a process comprising the steps of:
- forming a plurality of field oxide regions on said substrate to isolate a plurality of active areas;
forming a lightly doped region at one of said active areas;
forming a doped silicon layer including dopants on said lightly doped region at said one active area and on the field oxide regions isolating said one active area;
forming a patterned first dielectric layer on said doped silicon layer to define a gate area;
forming a second dielectric layer on said first dielectric layer and said doped silicon layer;
forming a third dielectric layer on said second dielectric layer;
anisotropically etching said third and second dielectric layers to form a plurality of spacer regions surrounding said gate area and to expose said doped silicon layer at said gate area;
forming a groove at said gate area by etching said exposed doped silicon layer and said substrate;
forming a gate oxide layer in said groove and forming said source and said drain in said substrate by substantially driving said dopants in said doped silicon layer into said substrate; and
forming said gate electrode in said groove.
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Abstract
A process for fabricating a semiconductor device comprising a source, a drain, and a gate electrode having an increased effective gate length. A semiconductor device is fabricated by a process comprising the following steps: forming active areas separated by field oxide regions; forming a lightly doped region in each active area; forming a heavily doped p-Si (or a-Si) layer; depositing and patterning several dielectric layers to form a gate area surrounded by vertical spacers; forming a groove in the gate area and the substrate; forming a gate oxide layer in the groove and driving dopants in the doped p-Si (or a-Si) layer into the substrate to form the source and the drain; and forming a gate electrode in the groove.
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Citations
7 Claims
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1. A semiconductor device, having a source, a drain and a gate electrode, fabricated by a process comprising the steps of:
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forming a plurality of field oxide regions on said substrate to isolate a plurality of active areas; forming a lightly doped region at one of said active areas; forming a doped silicon layer including dopants on said lightly doped region at said one active area and on the field oxide regions isolating said one active area; forming a patterned first dielectric layer on said doped silicon layer to define a gate area; forming a second dielectric layer on said first dielectric layer and said doped silicon layer; forming a third dielectric layer on said second dielectric layer; anisotropically etching said third and second dielectric layers to form a plurality of spacer regions surrounding said gate area and to expose said doped silicon layer at said gate area; forming a groove at said gate area by etching said exposed doped silicon layer and said substrate; forming a gate oxide layer in said groove and forming said source and said drain in said substrate by substantially driving said dopants in said doped silicon layer into said substrate; and forming said gate electrode in said groove. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification