Browse Prior Art Database

Process for Ion Implantation of Arsenic Emitters

IP.com Disclosure Number: IPCOM000059880D
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Blouse, JL: AUTHOR [+7]

Abstract

This article describes the processing required to form Arsenic Emitters with a nominal depth of 0.5 micron. Other N+ contacts are formed simultaneously for low ohmic contacts to Collectors, N Resistors and Schottky Barrier Diode Cathodes. The general cross section of the emitter structure 1 is shown in the drawing. A nitride layer 2 over an oxide layer 3 is formed after the standard base diffusion. A critical image mask is used to etch the nitride over all contact regions. Processing unique to the implant process begins immediately after the nitride etch. The same critical mask used to etch the nitride is employed to etch the SiO2 to silicon in all regions covered by post base oxidation. The method employed for etching the SiO2 depends on the structural dimensions of the product.

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Process for Ion Implantation of Arsenic Emitters

This article describes the processing required to form Arsenic Emitters with a nominal depth of 0.5 micron. Other N+ contacts are formed simultaneously for low ohmic contacts to Collectors, N Resistors and Schottky Barrier Diode Cathodes. The general cross section of the emitter structure 1 is shown in the drawing. A nitride layer 2 over an oxide layer 3 is formed after the standard base diffusion. A critical image mask is used to etch the nitride over all contact regions. Processing unique to the implant process begins immediately after the nitride etch. The same critical mask used to etch the nitride is employed to etch the SiO2 to silicon in all regions covered by post base oxidation. The method employed for etching the SiO2 depends on the structural dimensions of the product. *When the nitride contact is relatively thick and the oxide thickness is relatively thin, a strong acid wet etch is employed. Dilution ratios are selected to ensure complete, uniform opening of the contact to silicon. Any residual oxide in the contact impedes ion penetration to the silicon layer which results in device parametric variation and/ or failure. The etch time is controlled to maintain the oxide undercut of the nitride. This ensures proper passivation of the emitter-base junction which impedes leakage. *When the contact is relatively thin and/or the oxide thickness is relatively thick, reactive ion etching is employed. This eliminates the oxide undercut/E-B passivation concern with the more critical dimension products. Laser ellipsometry detects the Si-SiO2 interface by measuring the index of refraction of the etching interface. Etching is continued beyond end-point detection to account for variations in the ox...