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US 4,231,057 AGranted
Semiconductor device and method for its preparation
AssigneeFujitsu Limited
InventorsYoshinobu Momma, Yunosuke Kawabe, Osamu Hataishi
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Abstract
An improved means and method for isolating semiconductor devices on a semiconductor substrate, comprising a shallow region formed between the semiconductor substrate and an epitaxial layer of each device, and between a buried layer of each device and an isolation region separating adjacent devices. The shallow region has conductivity type opposite to that of the semiconductor substrate and higher impurity concentration than that of the epitaxial layer.
Claims10
A semiconductor device comprising:
- a semiconductor substrate having a first conductivity type;
- a plurality of buried layers of a second conductivity type opposite to said first type formed in selected portions of the surface of said semiconductor substrate an epitaxial layer of said second conductivity type formed over said semiconductor substrate and said layers;
- a plurality of isolation regions formed between adjacent ones of said buried layers, said isolation regions extending downward from the surface of said epitaxial layer to said semiconductor substrate;
- an epitaxial layer of said second conductivity type formed over said semiconductor substrate and said buried layers;
- a plurality of first regions having said first conductivity type formed in said epitaxial layer corresponding to said buried layers, each said first region extending to respectively contact said isolation regions;
- and
- a plurality of second regions having said second conductivity type formed between said semiconductor substrate and said epitaxial layer, and between said isolation regions and said buried layers, said second conductivity type regions having higher conductivity than that of said epitaxial layer and have a depth shallower than the deepest portion of the buried layers.
4 more elements
Dependencies are inferred from the claim text.