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Etching Silicon Nitride and Silicon Oxide using Ethylene Glycol / Hydroflouric Acid Mixtures
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Published at the Electrochemical Society - 1999 Joint International Meeting Sixth International Symposium on Cleaning Technology in Semiconductor Device Manufacturing Honolulu, Hawaii, October 17-22, 1999
Alison Wood, IBM Microelectronics Division, Stefan Detterbeck, SEZ AG
Abstract - Concentrated (49%) aqueous HF and ethylene glycol solutions were investigated for a wet strip process requiring a LPCVD Si3N4 to thermal SiO2 etch rate selectivity of between 1 and 2. Si3N4 etch rates of higher than 20 nm per minute were also desired to obtain high throughputs on the single-wafer spray tool. Water, temperature, and HF concentration were found to play a significant role in defining both the etch rates and etch-rate selectivity of LPCVD Si3N4 and thermal SiO2 films. The desired Si3N4 : SiO2 selectivity was achieved at low HF concentrations; at higher HF concentrations, the selectivity decreased rapidly below 1. Water additions to the system produced similar results. Particulate contamination levels were also significantly reduced when a deionized water rinse was used ....
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