A pattern is formed by applying a positive resist composition comprising a polymer comprising 7-oxanorbornane ring-bearing recurring units and acid labile group-bearing recurring units and an acid generator onto a substrate to form a resist film, heat treating and exposing the resist film to radiation, heat treating and developing the resist film with a developer, and causing the resist film to crosslink and cure with the aid of acid and/or heat. A second resist pattern is then formed in the space area of the first resist pattern. The double patterning process reduces the pitch between patterns to one half.