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Silicon Cleaning Methods Compared at Metal Concentrations Below 1E10 atoms/cm2

Published online by Cambridge University Press:  10 February 2011

Joseph Ilardi ,
Rajananda Saraswati  and
George Schwartzkopf
Joseph Ilardi
Affiliation:
Mallinckrodt Baker, Inc., Research and Technology Development Department, Phillipsburg, NJ
Rajananda Saraswati
Affiliation:
Mallinckrodt Baker, Inc., Research and Technology Development Department, Phillipsburg, NJ
George Schwartzkopf
Affiliation:
Mallinckrodt Baker, Inc., Research and Technology Development Department, Phillipsburg, NJ
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Abstract

An alkaline aqueous silicon wafer cleaner has been developed which reduces trace metal contamination levels on “p-type” unpatterned silicon wafers to below 1E10 atoms/cm2 without acidic cleaning. This patented technology uses a specially formulated buffering system consisting of an oxidation resistant chelating agent and salt of a weak acid. The aqueous cleaner maintains a stable pH of about 9.5 over a wide range of dilutions, temperatures, hydrogen peroxide concentrations and bath aging times. A single-step bath, megasonic bath or spray clean with this formulation leaves the chemical oxide on the silicon wafer surface free of particles, atomically smooth, free of organics and lower in trace metal contamination levels than similar surfaces cleaned with conventional formulations.

An analytical method was developed which allows the reliable detection of trace metals on silicon wafer surfaces down to 1E8 atoms/cm2 for aluminum, calcium, copper, iron, nickel, sodium and zinc. The procedure uses an ICP-MS with a concentric nebulizer and a desolvator. The acids used were ultrapure to keep the blanks to a very minimum and analyses were run in a class 10 clean room. The trace metals on the wafer were extracted using known amounts of ultrapure acids and were directly aspirated using a special arrangement with the concentric nebulizer. The J.T. Baker cleaner was compared to and outperformed the conventional RCA-1&2 clean and dilute RCA-1&2 chemistries using ultrapure ammonium hydroxide, hydrochloric acid and hydrogen peroxide.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 606: Symposium NN – Chemical Processing of Dielectrics, Insulators & Electronic Ceramics , 1999 , 245
Copyright
Copyright © Materials Research Society 2000

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