METHOD AND COMPOSITION FOR ETCHING OF SILICON NITRIDE FILM FOR MANUFACTURING SEMICONDUCTOR DEVICE, AND SEMICONDUCTOR DEVICE MANUFACTURED BY THE METHOD

摘要

PROBLEM TO BE SOLVED: To etch a silicon nitride film with ease and in a short time by, relating to an etching composition, mixing a hydrofluoric acid of wt.% of specific range with a phosphate water solution of wt.% of specific range and changing the mixture ratio. SOLUTION: A hydrofluoric acid of 10-90 wt.% (content of HF is 1-10 wt.%) is mixed with a phosphate water solution of 90-10 wt.% (content of phosphate is 80-90 wt.%) to obtain an etching composition. The mixture ratio between the hydrofluoric acid and the phosphate solution differs depending on required etching rate of a silicon nitride. An etching speed is decreased as mixture ratio of hydrofluoric acid is increased before the mixture ratio of phosphate solution reaches 10%, while the etching rate is increased in proportion to the increase of mixture ratio of hydrofluoric acid after the mixture ratio of phosphate solution exceeds 10%. Thus, a silicon nitride film on a wafer is etched for removal at a high rate.