Photomask and pattern forming method

摘要

A photomask is used for transferring a mask pattern onto a semiconductor substrate. The mask pattern includes a junction at which two line patterns are connected to each other with one line pattern being orthogonal to the other line pattern so as to form a T-shape, or a proximity portion at which two line patterns are located close to each other with one line pattern being substantially orthogonal to the other line pattern so as to form a T-shape. A small pattern is formed on a side edge of the line pattern in the vicinity of the junction or the proximity portion so as to form a wide portion of the line pattern. The small pattern is provided within the range between 0.79 and 1.8 lambda/(NA.K) of a distance from the neighboring side edge of the other line pattern, where lambda is the wavelength of exposure illumination light, NA is the numerical aperture of a lens used, and K is a transfer reduction ratio.