Method for fabricating semiconductor devices by use of an N.sup.+ buried layer for complete isolation
First Claim
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1. A method for fabricating a semiconductor memory device, comprising the steps of:
- forming an N-type buried layer in a substrate;
forming an epitaxial silicon layer above said buried layer;
forming a plurality of P-type regions in said epitaxial layer;
forming a plurality of contacts to said N-type buried layer through said epitaxial layer wherein the plurality of contacts are spaced at regular intervals throughout the memory array; and
forming an array of N-channel field effect devices in said P-type regions.
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Abstract
An N+ buried layer is formed under all the N-channel devices in the memory array of an integrated circuit device. The N+ buried layer can also be formed under N-channel input/output devices. The N+ buried layers include contacts to the power supply. Such a device layout provides for complete isolation of the memory array from the remainder of the circuitry. The isolation of the N-channel input/output devices also provides for enhanced immunity to input/output noise.
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Citations
15 Claims
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1. A method for fabricating a semiconductor memory device, comprising the steps of:
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forming an N-type buried layer in a substrate; forming an epitaxial silicon layer above said buried layer; forming a plurality of P-type regions in said epitaxial layer; forming a plurality of contacts to said N-type buried layer through said epitaxial layer wherein the plurality of contacts are spaced at regular intervals throughout the memory array; and forming an array of N-channel field effect devices in said P-type regions. - View Dependent Claims (2, 3, 4)
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5. A method for fabricating semiconductor integrated devices, comprising the steps of:
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forming an N-type buried layer and a P-type buried layer in a substrate; forming an epitaxial silicon layer above said buried layers; forming a plurality of P-type regions in said epitaxial layer at least one over said N-type buried layer; forming at least one contact to said N-type buried layer through said epitaxial layer; and forming at least one N-channel field effect device in said at least one P-type region over said N-type buried layer. - View Dependent Claims (6, 7, 8, 9, 10)
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11. A method for fabricating semiconductor integrated devices, comprising the steps of:
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forming an N-type buried layer in a substrate; forming an epitaxial silicon layer above said buried layer; forming a plurality of P-type regions in said epitaxial layer; forming a contact to said buried layer through said epitaxial layer, said contact forming a continuous structure around a memory array, and forming a plurality of N-channel field effect devices in said P-type regions. - View Dependent Claims (12, 13, 14, 15)
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Specification