Patterning process

A patterning process comprising the steps of:

• (1) forming on a substrate an organic underlayer film, a silicon-containing middle layer film thereon, and further an upper layer resist film thereon;
• (2) subjecting the upper layer resist film to exposure and development to form an upper layer resist pattern;
• (3) transferring the upper layer resist pattern to the silicon-containing middle layer film by dry etching using the upper layer resist film having the formed upper layer resist pattern as a mask, and further transferring the upper layer resist pattern to the organic underlayer film by dry etching using the silicon-containing middle layer film having the transferred upper layer resist pattern as a mask to form an organic underlayer film pattern;
• (4) forming an inorganic silicon film by a CVD method or an ALD method so as to cover the organic underlayer film pattern;
• (5) removing a portion of the inorganic silicon film by dry etching to expose an upper portion of the organic underlayer film pattern;
• and
• (6) removing the organic underlayer film pattern with a stripping liquid to form an inorganic silicon film pattern whose pattern pitch is ½ of that of the upper layer resist pattern.