Abstract: A photo-resist mask is removed from an inter-level insulating structure by using plasma produced from N.sub.x H.sub.y gas, and the plasma does not make an organic insulating layer forming part of the inter-level insulating structure hygroscopic, because SiCH.sub.3 bond is never replaced with Si--OH bond during the removal of the photo-resist mask.

Abstract: An apparatus for generating plasma, includes a cylindrical vacuum chamber made of dielectric substance, the chamber being open only at a bottom thereof and having a height of 50 mm or smaller, at least one antenna coil disposed around the chamber for receiving high frequency power therein, and at least one electromagnetic coil disposed around the antenna coil. The cylindrical vacuum chamber may be replaced with a plate made of a dielectric substance. The apparatus is operative to carry out photoresist using etching without leaving any residue under a high selection ratio to the photoresist. In addition, the etching product does not tend to adhere to the vacuum chamber, and it would be easy to remove etching product from the vacuum chamber, even if the product adheres to the vacuum chamber.