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Method for Fabrication of Bird's Beak-Less ROI Using Nitrogen Ion Implant and High Pressure Oxidation

IP.com Disclosure Number: IPCOM000042796D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Ahlgren, DC: AUTHOR [+3]

Abstract

A "bird's beak" is formed from lateral diffusion of oxygen under an oxide pad in conventional recessed oxide isolation (ROI) growth. This bird's beak can be reduced by decreasing the oxide pad, which removes silicon nitride from the silicon surface. This method, however, has been shown to result in low leakage-limited yield due to dislocations produced from high stress of nitride directly on silicon. Described is a method using low dose ion implantation of nitrogen into the single crystal silicon which serves to inhibit growth of ROI in non-isolation regions. This effect lasts [*] approximately 2 hours at 1000ŒC depending on implant dose and energy. To grow reasonable ROI without losing this barrier, it is necessary to use high pressure oxidation to decrease oxidation time from 6 hours to 1 hour.

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Method for Fabrication of Bird's Beak-Less ROI Using Nitrogen Ion Implant and High Pressure Oxidation

A "bird's beak" is formed from lateral diffusion of oxygen under an oxide pad in conventional recessed oxide isolation (ROI) growth. This bird's beak can be reduced by decreasing the oxide pad, which removes silicon nitride from the silicon surface. This method, however, has been shown to result in low leakage- limited yield due to dislocations produced from high stress of nitride directly on silicon. Described is a method using low dose ion implantation of nitrogen into the single crystal silicon which serves to inhibit growth of ROI in non-isolation regions. This effect lasts [*] approximately 2 hours at 1000OEC depending on implant dose and energy. To grow reasonable ROI without losing this barrier, it is necessary to use high pressure oxidation to decrease oxidation time from 6 hours to 1 hour. The oxidation barrier can then be de-activated using N2 anneal, returning the silicon to its normal oxidation properties. The method for fabrication of bird's beak-less ROI is as follows: 1. Use of standard processing through epi reox to obtain the structure of Fig. 1. 2. Nitrogen ion implantation (approximate conditions: 100 keV, 5 x 1015 cm-2). 3. ROI P/R (photoresist) and trench etch to produce structure of Fig. 2. 4. High pressure ROI oxidation (approximate conditions: 920 C, 60 min., 10 atm). 5. N2 anneal (approximate conditions: 1000OEC, 2 hrs.). 6. Standard proc...