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Making Complementary Metal Oxide Semiconductor Devices on Insulating Substrates

IP.com Disclosure Number: IPCOM000080455D
Original Publication Date: 1973-Dec-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 81K

Publishing Venue

IBM

Related People

Allen, JW: AUTHOR [+2]

Abstract

Standard complementary metal-oxide semiconductor processing requires separate masking steps for each of the following: (1) the N+ diffusion for N channel sources and drains; (2) the P+ diffusion for P channel sources and drains; and (3) forming the thick oxide in the field regions while maintaining thin oxide in the channels.

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Making Complementary Metal Oxide Semiconductor Devices on Insulating Substrates

Standard complementary metal-oxide semiconductor processing requires separate masking steps for each of the following: (1) the N+ diffusion for N channel sources and drains; (2) the P+ diffusion for P channel sources and drains; and (3) forming the thick oxide in the field regions while maintaining thin oxide in the channels.

In this process, the masking step used in Step 3 can be eliminated by using standard source-drain diffusions to diffuse N-type dopant (Step 1) into the field region of the P channel field-effect transistor, and P-type dopant (Step 2) into the field region of the N channel field-effect transistor. This results in a thick SiO(2) and a high surface impurity concentration in the field regions, while deleting masking Step 3. In addition, this process decreases the possibility of field surface inversion, since high-dopant levels are present in the field regions.

The initial device structure, having pairs of monocrystalline Si layers 10 and 12 on an insulating substrate 14 and surrounded by thick oxide 16, is formed by depositing a layer of monocrystalline Si, implanting N or P-type ions into selected regions, masking the regions with an oxidation resistant mask, selectively etching Si around the pairs of monocrystalline regions, and thermally oxidizing the remaining Si.

With a first mask diffusion, openings are formed in layers 18 and 20 for source and drain windows 22...