US Patent 7943285 Pattern formation method

After formation of an underlayer film and an intermediate layer film, a resist pattern formed by the first pattern exposure with the first resist film and the second pattern exposure with the second resist film is transferred to the intermediate layer film. The underlayer film is etched using an intermediate layer pattern as a mask to form an underlayer film pattern. Herein, the first and second resist films are chemically amplified resist films. The second resist film contains a greater amount of additive which improves the sensitivity of the resist or which improves the alkaline solubility of resist exposed part.