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THREE-DIMENSIONAL SILICON ON OXIDE DEVICE ISOLATION

IP.com Disclosure Number: IPCOM000005640D
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2001-Oct-23
Document File: 2 page(s) / 98K

Publishing Venue

Motorola

Related People

Harrison B. Haver: AUTHOR [+2]

Abstract

A novel technique has been devised for achieving full 3-D deviceoxide isolation by utilizing a partially masked oxygen ion implant into a silicon substrate to produce a modified silicon-on-insulator (SOI) structure. This ap preach may be utilized with either field effect or junction device technology to eliminate deleterious device interactions such as regenerative latch-up and transient upset.

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MOIOROLA Technical Developments Volume 7 October 1987

THREE-DIMENSIONAL SILICON ON OXIDE DEVICE ISOLATION

by Harrison B. Haver and Dean P Frazier

ABSTRACT

   A novel technique has been devised for achieving full 3-D deviceoxide isolation by utilizing a partially masked oxygen ion implant into a silicon substrate to produce a modified silicon-on-insulator (SOI) structure. This ap preach may be utilized with either field effect or junction device technology to eliminate deleterious device interactions such as regenerative latch-up and transient upset.

PROCESS:

   Referring to Figure 1, a thin silicon dioxide layer 2 is applied to silicon substrate 1. Then a suitable ion implant masking material 3 is applied over oxide layer 2. The masking material may be silicon nitride, silicon oxynitride or similar material. Masking material 3 is patterned using conventional silicon microcircuit photolithography and etch techniques. Ionic oxygen 4 is implanted into the silicon substrate 1 using conven- tional techniques. The oxygen ion species and implant energy are selected such that the oxygen penetrates the unmasked oxide layer 2 and passes into the substrate to a typical peak concentration depth of 0.3-0.6 micron, forming buried implant region 5. The thickness of the masking material 3 is chosen such that approximately 50 - 75% of the oxygen ions 4 penetrate the masking material and oxide layer, forming subsurface implant region 6, with a peak oxygen concentration at or very near the silicon surface of substrate 1.

   Following oxygen implant, masking material 3 is removed using conventional mask strip techniques. The silicon substrate is then subjected to a high temperature anneal according to conventional technology for form- ing SOI substrates by implantation of oxygen. Referring to Figure 2, the implanted oxygen in regions 5 and 6 combines with local silicon during high temperat...