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Elimination of Reactive Ion Etching Trench Induced Defects

IP.com Disclosure Number: IPCOM000052160D
Original Publication Date: 1981-May-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Das, G: AUTHOR [+2]

Abstract

Controlling the ratio of silicon dioxide (SiO(2)) and silicon nitride (Si(3)N(4)) film thicknesses, used as the oxidation barrier for forming a recessed oxide isolation (ROI) structure, can reduce or eliminate induced dislocations. Using the wet etching technique to form the ROI trench, the oxide/nitride ratio of 1.6 is satisfactory. Since wet etching is an isotropic etching process, the ROI trench has a slope of 45 degrees, as seen in Fig. 1. However, the reactive ion etching (RIE) technique alternative produces a slope that is about 70 degrees, as shown in Fig. 2.

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Elimination of Reactive Ion Etching Trench Induced Defects

Controlling the ratio of silicon dioxide (SiO(2)) and silicon nitride (Si(3)N(4)) film thicknesses, used as the oxidation barrier for forming a recessed oxide isolation (ROI) structure, can reduce or eliminate induced dislocations. Using the wet etching technique to form the ROI trench, the oxide/nitride ratio of 1.6 is satisfactory. Since wet etching is an isotropic etching process, the ROI trench has a slope of 45 degrees, as seen in Fig. 1. However, the reactive ion etching (RIE) technique alternative produces a slope that is about 70 degrees, as shown in Fig. 2.

The RIE-produced trenches are subjected to higher stress concentration during the ROI oxidation, since RIE trenches are steeper than wet etch trenches.

The use of a ratio of SiO(2)/Si(3)N(4) of 3.2 or better provides protection for increased stress during the ROI formation which could otherwise induce dislocations in the silicon structure.

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