SEDL / STP / STP1382-EB / STP13486S

Application of Quantox Measurements to Identify Phosphorus Contamination in Silicon Wafers

Dexter, MA
Process Engineer, Texas Instruments Incorporated, Dallas, TX

Hasslinger, KM
Process Engineer, Texas Instruments Incorporated, Dallas, TX

Fritz, JR
Process Engineer, Texas Instruments Incorporated, Dallas, TX

Ullo, CA
Diffusion Section Manager, Texas Instruments Incorporated, Dallas, TX

Pages: 11    Published: Jan 2000

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Abstract

During a three-year period, MOS fab experienced a 0.3% parametric failure rate on LOCOS devices. The observed failure mode is high N- and low P-channel current leakage. Only wafer number five of a lot was affected. This selective (believed) phosphorus contamination was appropriately named the “Phantom Wafer Failure”. MOS fab implemented routine monitoring on all oxidation furnaces using the Keithley Quantox characterization tool in December 1997. Flatband voltage and mobile ion concentration were monitored using this tool. It was only after implementing this monitoring that the fab was able to identify the source of the phosphorus contamination. This report illustrates using the Keithley Quantox to identify the source of this phosphorus contamination.