Browse Prior Art Database

Fabrication of Small Contacts to Source and Drain of IGFET's

IP.com Disclosure Number: IPCOM000082660D
Original Publication Date: 1975-Jan-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

De La Moneda, FH: AUTHOR

Abstract

Described is a method employing silicon nitride coatings to mask the growth of a thermal silicon dioxide layer in the formation of contact via holes, to connect metallurgical contacts to the source and drain regions of a field-effect transistor (FET) device.

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Fabrication of Small Contacts to Source and Drain of IGFET's

Described is a method employing silicon nitride coatings to mask the growth of a thermal silicon dioxide layer in the formation of contact via holes, to connect metallurgical contacts to the source and drain regions of a field-effect transistor (FET) device.

The process commences with the step of growing a thermal oxide 2 on the surface of a silicon substrate 1, having a sufficient thickness to serve as an implantation mask during a subsequent ion implantation step, or as a diffusion mask for an alternate diffusion step used in the formation of the source and drain regions 3 and 4. After forming the source and drain regions 3 and 4 by either ion implantation or thermal diffusion, a silicon nitride layer is deposited on all exposed surfaces, and the silicon nitride masks 5 and 6 are etched so as to cover the source and drain regions 3 and 4, respectively.

The next step is the growth of a thermal oxide layer 7 on all exposed silicon and silicon dioxide surfaces, to serve as the field oxide for the finished device. Note that the thermal oxide will not form in a region masked by the silicon nitride layers 5 and 6, which serve to define contact regions for the source and drain of the finished device. The next step consists of differentially etching out the silicon nitride layers 5 and 6, to permit contact by the source and drain electrodes. Subsequent steps follow the conventional techniques of forming the g...