Abstract: A photomask for use in forming a photoresist pattern by projection exposure, comprising opaque stripes respectively arranged on a mask substrate at a given pitch and phase shifters formed alternately on light-transmissive areas between said opaque stripes. The widths of the opaque stripes are larger than those of said light-transmissive areas whereby the edges of said phase shifters on said light-transmissive areas are prevented from being transferred to a wafer.

Abstract: In a photomask for use in forming a resist pattern by projection exposure of a resist through the photomask, a phase shifter has a first edge part whose image is to be transferred and a second edge part whose image is not to be transferred. A light attenuator is provided to cover the first edge part. The light attenuator may include an array of opaque stripes arranged at a pitch of not more than the limit of resolution, i.e., 0.5.times..lambda./NA, where .lambda. represents the wavelength of light used for the projection exposure, and NA represents the numerical aperture of an optical system used for the projection exposure. In another embodiment, the light attenuator is formed to cover a shifter edge part in alignment with a line of a transmission mask. In a further embodiment, one or more light attenuators having different transparency are used to obtain lines of a resist pattern having different widths.

Abstract: In a photoresist pattern formation by exposure using first and second photomasks, the first photomask has a transparent part, a rectangular opaque part having a first pair of sides and a second pair of sides, and a phase shifter, having a first edge crossing one of the first pair of sides, so that a part of the first edge is in the transparent part, and the second photomask has a transparent part, a rectangular opaque part corresponding to the rectangular opaque part of the first photomask, and a stripe-shaped opaque part corresponding to the first part of the first edge of the phase shifter. The rectangular opaque part of the first photomask is expanded in the direction of the first pair of sides, while the rectangular opaque part of the second photomask is expanded in the direction the second pair of sides. The amount of expansion is preferably not smaller than a misalignment tolerance.