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High Low RIE Process

IP.com Disclosure Number: IPCOM000045813D
Original Publication Date: 1983-Apr-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Lechaton, JS: AUTHOR [+2]

Abstract

Use of high reactive ion etch (RIE) rates is desirable for deep etching, such as opening a deep isolation trench in silicon wafers to reduce the etch time. These high etch rates require higher power to the substrate electrode. However, high energy ion bombardment results in crystalline damage to the silicon wafer which is typically 10 to 20 nanometers deep. Thermal oxidation of this damaged silicon can result in stacking faults, which could, for example, traverse large distances and cause device degradation.

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High Low RIE Process

Use of high reactive ion etch (RIE) rates is desirable for deep etching, such as opening a deep isolation trench in silicon wafers to reduce the etch time. These high etch rates require higher power to the substrate electrode. However, high energy ion bombardment results in crystalline damage to the silicon wafer which is typically 10 to 20 nanometers deep. Thermal oxidation of this damaged silicon can result in stacking faults, which could, for example, traverse large distances and cause device degradation.

A technique to prevent such a degradation involves opening the trench at high power and at high etch rates to the nearly desired depth. The power is then considerably reduced to, for example, between 0.3 to 0.15 W/cm from a high value of more than 0.8 W/cm for the silicon etch. The etching is continued to remove about 20 to 30 nanometers of silicon to remove the damaged layer at this low power. This combination of high-low power etching improves the quality of the silicon surface after the etching.

This method is applicable to thick silicon dioxide etching to a silicon surface where the etch rate selectivity between the silicon dioxide and the silicon is high. In this case, the silicon surface in the silicon dioxide window can get damaged by the high energy ion penetration which is not significantly removed by the high selectivity etch. By reducing the power in the last one hundred or so nanometers of silicon dioxide, this damage can be m...