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Forming Sidewall Dielectric Isolation of Integrated Circuit Devices

IP.com Disclosure Number: IPCOM000082962D
Original Publication Date: 1975-Mar-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 75K

Publishing Venue

IBM

Related People

Schaible, PM: AUTHOR [+2]

Abstract

It is known in the art to form sidewall dielectric isolation of integrated circuit devices by etching moats in the surface, oxidizing the exposed silicon to form a surface layer of SiO(2), depositing a layer of polycrystalline silicon over the SiO(2) layer, and abrading the excess polycrystalline silicon down to the SiO(2) layer. The abrading step is objectionable since the devices are easily damaged, it is expensive, and difficult to control.

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Forming Sidewall Dielectric Isolation of Integrated Circuit Devices

It is known in the art to form sidewall dielectric isolation of integrated circuit devices by etching moats in the surface, oxidizing the exposed silicon to form a surface layer of SiO(2), depositing a layer of polycrystalline silicon over the SiO(2) layer, and abrading the excess polycrystalline silicon down to the SiO(2) layer. The abrading step is objectionable since the devices are easily damaged, it is expensive, and difficult to control.

In this process for forming sidewall dielectric isolation, the conventional abrading step necessary to remove the excess insulating material is eliminated.

In this process, the semiconductor substrate will typically consist of a monocrystalline semiconductor wafer 10 having an overlying epitaxial layer 12 of a different conductivity, and a low resistivity subcollector region 14, as shown in Fig. 1. Moats 16 are etched to define the device regions 18 using conventional masking and subtractive etching techniques. As indicated, moats 16 extend through layer 12 and the PN junction 19 between layer 12 and 10.

As indicated in Fig. 2, the surface of the layer 12 including the walls of moats 16, are thermally oxidized forming a thin layer 20 of SiO(2) In this process, the forming of layer 20 is optional.

As indicated in Fig. 3, a layer 22 of an organic polymer, typically polyimide, is formed on the surface over layer 20. Since the polyimide is deposited in a liquid...