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Browse Prior Art Database

Dielectric Isolation

IP.com Disclosure Number: IPCOM000080756D
Original Publication Date: 1974-Feb-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Broadie, RW: AUTHOR [+2]

Abstract

With the advent of higher density, high speed and complementary circuits, the need for dielectric rather than junction isolation has increased in the past few years. This problem has heretofore been attacked through the use of chemical etches, electrochemical etches, and silicon on insulating substrates.

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Dielectric Isolation

With the advent of higher density, high speed and complementary circuits, the need for dielectric rather than junction isolation has increased in the past few years. This problem has heretofore been attacked through the use of chemical etches, electrochemical etches, and silicon on insulating substrates.

Shown is a simple, effective technique for the fabrication of monocrystalline silicon islands in an aluminum oxide matrix.

The structure is prepared from a silicon substrate 1 in which moats 2 are etched into the front surface, through the use of oxidation and photolithographic techniques to the depth desired for the silicon island thickness. After etching, the oxide is removed and a film of high-temperature aluminum oxide 3 is deposited followed by deposition of a suitable support substrate 4, as for example, polysilicon, see Fig. 2.

The back side of the silicon substrate 1 is then polished through the use of chemical-mechanical polishing techniques (e.g. copper-displacement). As the polishing pad reaches the aluminum oxide 3, the polishing and etching action stops because the pad will no longer touch the silicon 1. In substance, it will be held back by the mechanical stop 5 of aluminum oxide 3. Any nonuniformity will be removed until all of the aluminum lands 5 touch the polishing pad. The aluminum oxide will not be chemically or mechanically attacked, due to its highly dense molecular structure. The resultant structure is shown in Fig. 3....