As a pattern size of device gets smaller, its aspect ratio is increasing. As a result, a film with high etching resistance, hard mask, is required during the etching process in the patterning. However high etching resistant film cannot be removed in a conventional removal process after etching. OMNIS offers a solution which selectively removes films by way of its high selectivity for films with high etching resistance as well as underlying films such as oxides and nitrides.