University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Website: @unf

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Classification: Metal -> silicon wafer

Citations 1

"Measurement Of Trace Metallic Contaminants On Silicon Wafer Surfaces In Native And Dielectric Silicon Oxides By Vapor Phase Decomposition Flow Injection Inductively Coupled Plasma Mass Spectrometry"
J. Electrochem. Soc. 1993 Volume 140, Issue 4 Pages 1105-1109
J. Fucsko, S. S. Tan, M. K. Balazs

Abstract: The concentration of trace metals on silicon wafer surfaces was measured using a novel highly sensitive multi-element analytical method, called vapor phase decomposition flow injection inductively coupled plasma-mass spectrometry (ICP-MS). Metallic contaminants result in a deterioration in the performance and yield of semiconductor devices. ICP-MS uses hydrogen fluoride vapor to decompose and release metal contaminants from surface oxides. The metals are collected by scanning a small drop of dilute acid solution throughout the surface of the wafer and are measured by ICP-MS using flow injection sample introduction. As many as 60 elements can be determined with detection limits ranging from 108 to 1011 atom/cm2. ICP-MS has the potential to serve as a reference technique for the calibration of surface analytical methods, as well as offering an improved technique for measuring trace metals. One or more Si wafers were loaded into a specially constructed vapor-phase decomposition box containing a reservoir of HF solution The exposure time depends on the thickness of the oxide layer, 20 min for 15-30 .angstrom., 3-12 h for 2000-10 000 .angstrom.. A single drop of HF was then placed on the wafer surface and carefully rolled over the surface to extract the trace metals. The drop was transferred to a small sample tube and injected into the Ar ICP torch assembley with a cross-flow pneumatic nebulizer. Calibration was performed using multi-element standard solution For solution containing either 0.8 or 4.0 ppb of Mg, Cu, and Ni, and Cu the precision (n = 10) was ± 15% and ± 8%, respectively. The recovery of trace metals spiked on to bare Si wafers varied from 90-110% for Al, Cr, Fe, Ni and Na at surface concentration. of 5.67 x 1010-63.5 x 1010 atom/cm2. The recovery of Cu was 8.3% with the experimental conditions used. The detection limits were 108-109 atom/cm2 for Cr, Co, Fe, Pb, Mg, Mn, Ni, K, V, Zr, 2 x 1010 for Al and Fe and 1 x 1010 for Na. The procedure was applied to the determination of metal contaminants on bare Si wafers from different sources. Aluminum, Fe and Na are the most common metal contaminants.
Metals, trace Chromium Cobalt Iron Lead Magnesium Manganese Nickel Potassium Vanadium Zirconium Mass spectrometry Multielement