| 摘要 |
<p>PROBLEM TO BE SOLVED: To attain a photolithography having an illumination efficiency which is superior to that in a conventional oblique illumination method and capable of easily manufacturing a mask as compared with a phase shifting method. SOLUTION: The photomask R1 with a light shielding film pattern 3 formed on one main surface of a glass substrate 2 and with a diffraction grating 5 formed on the other main surface is set on a normal stepper, and the photomask R1 is illuminated from the diffraction grating side. The illuminating light is diffracted by the diffraction grating 5, for example, negative zero-order diffracted light is obliquely made incident on the light shielding film pattern 3 after being transmitted through the glass substrate 1. Then, the same illumination as that in the oblique illumination method is obtained. The straight advancing component (zero-order light) outgoing from an aperture part 4 is inclined with respect to the optical axis of the stepper, then, only the zero-order light and positive 1st-order light are taken in a projecting lens 7, so that the depth of focus DOF can be enlarged while improving the resolution. By optimizing the pattern of the diffracted grating 5, the pattern dependency of the resolution is eliminated. A complicated pupil operation is entirely unnecessitated.</p> |
