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Reduction of Emitter-Base Defects with Reactive Ion Etching

IP.com Disclosure Number: IPCOM000045816D
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

Forney, GB: AUTHOR [+3]

Abstract

This article concerns a method for limiting emitter-base leakage and shorting due to failure of implanted arsenic to properly passivate the emitter-base junction insulation. The method features use of a reactive ion etch (RIE) to avoid wet etch isolation undercutting.

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Reduction of Emitter-Base Defects with Reactive Ion Etching

This article concerns a method for limiting emitter-base leakage and shorting due to failure of implanted arsenic to properly passivate the emitter-base junction insulation. The method features use of a reactive ion etch (RIE) to avoid wet etch isolation undercutting.

In the fabrication of implanted emitter bipolar devices, after the RIE of silicon nitride, buffered hydrofluoric acid is used to etch the silicon dioxide. This wet etch results in an undercutting of the silicon nitride due to silicon dioxide etching laterally of the silicon nitride opening. When arsenic is implanted to form the emitters and other N+ contacts, only the region exposed by the nitride opening receives arsenic implantation. During subsequent thermal annealing the arsenic must diffuse laterally under the silicon dioxide in order to passivate the emitter- base junction. When a contaminant is present in the emitter opening during implantation, it prevents arsenic from reaching the silicon underneath it and, further, lengthens the distance the arsenic must diffuse in order to achieve passivation. Many times passivation is not achieved, which results in emitter- base leakage and dead shorts which adversely affect device yields.

The occurrence rate of this defect can be reduced by employing RIE to etch the silicon dioxide. Use of the RIE thus avoids need for the hydrofluoric acid etch. Due to the vertical etching characteristics of RI...