Patent ID: 7972752

Claim:
A method of forming a resist pattern comprising the steps of: preparing a photomask for forming a resist pattern having a nonuniform film thickness on a main surface of a target substrate, the photomask including a plurality of mask cells arranged in the form of a matrix on a surface of a transparent mask substrate, a length of one side of each of the mask cells being smaller than a length corresponding to a resolution limit of an optical system of an exposure device, each mask cell including at least one of a light transmission region and a light shielding region, wherein the intensity of light passing through each mask cell depends on a ratio of an area of the light transmission region to an area of the mask cell; setting the optical system of the exposure device at a vertical focus position other than an optimal focus position, the optimal focus position being the vertical focus position at which the exposure device is focused on a resist film formed on the main surface of the target substrate, wherein the vertical focus position lies along a line oriented perpendicular to the main surface of the target substrate; exposing the resist film with light passing through the photomask; and developing the exposed resist film to obtain the resist pattern.