METHOD FOR ETCHING SILICON NITRIDE LAYER HAVING HIGH SELECTION RATIO

摘要

PURPOSE: A method for etching a silicon nitride layer is provided to reduce the etching speed of a silicon oxide layer and increase the etching speed of a silicon nitride layer by using the etching gas including CH2F2 gas under the substrate temperature of 40 and more degrees centigrade. CONSTITUTION: A buffer layer(22) is formed on an upper surface of a semiconductor substrate(10). The buffer layer is formed with a silicon oxide. A silicon nitride layer(24) is formed on an upper surface of the buffer layer. The silicon nitride layer is etched by using the etching gas including CH2F2 gas while the temperature of the semiconductor substrate exceeds 40 degrees centigrade. The etching gas further includes CF4 gas, inert gas such as argon, and O2 gas. The temperature of the semiconductor substrate is 60 to 100 degrees centigrade.