DRY ETCHING METHOD

PURPOSE:To reduce the influence of plasma irradiation damage upon device characteristics, and obtain a method capable of contributing to the yield improvement of semiconductor devices, by dividing an etching process into two stages, and making the composition ratio of oxygen to hydrocarbon based gas containing halogen elements higher than or equal to a specified value and lower than it, in the first stage and in the second stage, respectively. CONSTITUTION:Silicon insulating films 2, 3 are deposited on a semiconductor substrate 1. By using a resist pattern 4 formed on said films as a mask, the silicon insulating films 2, 3 are etched. In this case, the etching is divided into a first process and a second process. In the first etching process, the silicon insulating films 2, 3 are etched by using etching gas wherein the composition ratio of oxygen gas to hydrocarbon based gas containing halogen elements is higher than or equal to 10%. In the second etching process, gas wherein the above ratio is lower than 10% is used as the etching gas, and the films 2, 3 are etched while reaction product 5 is deposited. Next, oxygen plasma processing is performed.