Mask blank, method for manufacturing mask blank and transfer mask

A method for manufacturing a mask blank, comprising:

• forming a thin film for forming a transfer pattern on a substrate;
• forming a resist underlayer film on the thin film by applying a resist underlayer composition containing a polymer including a unit structure having a lactone ring and a unit structure having a hydroxyl group and heating the same;
• and
• forming a resist film by applying a resist composition on the resist underlayer film and heating the same,
• wherein in forming the resist film,
• a surface layer portion of the resist underlayer film is dissolved by applying the resist composition on the resist underlayer film, and a mixed component of a dissolved component of the resist underlayer film and the resist composition is formed on an interface between the resist underlayer film and the applied resist composition, and
• the resist film is formed by heating the mixed component together with the resist composition, and a mixed film is formed so as to be interposed between the resist underlayer film and the resist film.