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Protection of the Oxide Isolation Layer in Dielectrically Isolated Semiconductor Structures

IP.com Disclosure Number: IPCOM000094171D
Original Publication Date: 1966-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Doo, VY: AUTHOR [+2]

Abstract

In the fabrication of the more common forms of dielectrically isolated semiconductor structures, the resultant structure A consists of a number of silicon islands 1. These are isolated from each other and from the base substrate by thin layer 2 of dielectric material, generally SiO(2).

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Protection of the Oxide Isolation Layer in Dielectrically Isolated Semiconductor Structures

In the fabrication of the more common forms of dielectrically isolated semiconductor structures, the resultant structure A consists of a number of silicon islands 1. These are isolated from each other and from the base substrate by thin layer 2 of dielectric material, generally SiO(2).

After this structure is obtained it is usually necessary, in semiconductor device fabrication, to form an oxide layer, by dry or steam oxidation, on the single crystal silicon islands 1 several times and to remove the oxide layers at the end of each operation. The cumulative effect of performing all of these etching operations is to either wholly or partially remove the SiO(2) on the top of the hump 3 which separates the isolated single crystal regions 1 and thus exposes the polycrystalline silicon substrate 4 as in drawing 13.

The exposure of the polycrystalline silicon causes serious electrical defects when aluminum interconnecting lines are formed on the region where the hump is located. The top of the polysilicon hump is frequently found to be rough and irregular. This is due either to unevenness in etching out the channels, part of the process to form the hump, or during handling. The net effect is to make it comparatively difficult to form a pinhole-free oxide layer over the polysilicon hump, which makes it comparatively easy to short the aluminum lines to the polycrystalline silicon s...