| 摘要 |
<p>PROBLEM TO BE SOLVED: To make it possible to optimize an effective light source and to improve both of a contrast and depth by irradiating fine grid-like patterns having a specific pitch with light forming the effective light source of a rectangular annular shape constituting a region intersecting with the pupil. SOLUTION: When a contact hole array is irradiated with the rectangular annular effective light source, a pair of zero order light and first order light is made incident on a position symmetrical with respect to the Kx and Ky axes on the pupil. In such a case, there is no degradation in the contrast by defocusing. The pitch turns to s1=1/(4k1) with respect to the two-dimensional periodic contact hole array of 2k1(λ/NA) and s2 is determined according to contrast defocusing characteristics. Namely, s2 is determined by the required contrast at the required depth. The contrast defocusing characteristics which are nearly the same as quadrupole illumination consisting of a circular shape of the same radius as s2 are obtained and the ratio of the area occupying the pupil of the effective light source increases exceedingly. If s2=0.1 or below is attained, there is substantially no degradation in the contrast.</p> |
