Microlithography projection-exposure masks, and methods and apparatus employing same

Claim 2

A mask for microlithographically projecting a pattern onto a photosensitive substrate comprising single- and multiple-exposure areas, the mask comprising: (a) a first mask pattern for exposing the single-exposure areas of the photosensitive substrate; (b) at least a second and a third mask pattern for exposing the multiple-exposure areas of the photosensitive substrate; and (c) each of the mask patterns for exposing the multiple-exposure areas transmitting to the photosensitive substrate a lower illumination-light-flux intensity per exposure than the first mask pattern so that an average illumination-light-flux intensity transmitted to the single-exposure areas is substantially equal to an average illumination-light-flux intensity transmitted to the multiple-exposure areas after the multiple exposures.

Claim 3

The mask of claim 1, wherein each of the first mask pattern and the mask patterns for exposing the multiple-exposure areas comprises alternating light-transmissive sections and light-blocking sections, the light-blocking sections blocking transmission of illumination light to the photosensitive substrate, each of the light-transmissive sections defining at least one aperture for allowing illumination light to be distributed to the photosensitive substrate.

Claim 4

The mask of claim 2, wherein the first mask pattern defines apertures situated between the light-blocking sections.

Claim 5

The mask of claim 2, wherein each aperture in the mask patterns for exposing the multiple-exposure areas comprises spaced-apart, light-impermeable sections for reducing the distribution of illumination-light-flux intensity per exposure to the multiple-exposure areas.

Claim 6

The mask of claim 2, wherein the apertures of the first mask pattern have a first width and the apertures of the mask patterns for exposing the multiple-exposure areas each have at least a second width that is less than the first width.

Claim 7

The mask of claim 2, wherein the light-blocking sections of the first mask pattern are at least partially light transmissive and the light-blocking sections of the mask patterns for exposing the multiple-exposure areas are light-impermeable.

Claim 10

The method of claim 7, wherein, in steps (b) and (c), the multiple-exposure areas are exposed using a lower intensity of illumination-light flux per exposure than used during exposure of the single-exposure areas.

Claim 11

The method of claim 8, wherein the first and second mask patterns are defined on a first mask and the third mask pattern is defined on a second mask.

Claim 12

The method of claim 9, further comprising making a first exposure on the single-exposure areas and the multiple-exposure areas using the first and second mask patterns, respectively; replacing the first mask with the second mask; and making a second exposure of the multiple-exposure area using the second mask.

Claim 13

The method of claim 7, further comprising exposing the multiple-exposure areas a third time and adjusting the intensity of illumination-light flux distributed to the multiple-exposure areas per exposure so that the average intensity of illumination light flux distributed to the single-exposure areas, after one exposure, is substantially equivalent to the average intensity of illumination-light flux distributed to the multiple-exposure areas after three exposures.

Claim 14

A microlithographic projection-exposure apparatus, comprising: (a) an illumination-optical system for producing an illumination-light flux; (b) a first mask comprising a first mask pattern for projection, by one exposure, onto single-exposure areas of a photosensitive substrate and a second mask pattern for projection, by a predetermined number of multiple exposures, onto multiple-exposure areas of the substrate, the first mask being positionable downstream of the illumination-optical system for illumination by the illumination-light flux; (c) a second mask comprising a third mask pattern for projection, by a predetermined number of multiple exposures, onto the multiple-exposure areas of the substrate, the second mask being positionable downstream of the illumination-optical system for illumination by the illumination-light flux when the first mask is not being illuminated with the illumination-light flux; (d) a projection-optical system for receiving illumination light transmitted through the first or second mask from the illumination-optical system and projection-distributing the illumination light to the substrate, the second and third mask patterns being configured relative to the first mask pattern so as to produce, after a total predetermined number of multiple exposures of the multiple-exposure areas of the substrate, a total average intensity of illumination light on the multiple-exposure areas that is substantially equal to a total average intensity of illumination light produced by the one exposure of the first mask pattern on the single-exposure areas of the substrate.

Claim 15

A microlithographic projection-exposure apparatus, comprising: (a) an illumination-optical system for producing an illumination-light flux; (b) a first mask comprising a first mask pattern for projection, by one exposure, onto single-exposure areas of a photosensitive substrate and a second mask pattern for projection, by a predetermined number of multiple exposures, onto multiple-exposure areas of the substrate, the first mask being positionable downstream of the illumination-optical system for illumination by the illumination-light flux; (c) a second mask comprising a third mask pattern for projection, by a predetermined number of multiple exposures, onto the multiple-exposure areas of the substrate, the second mask being positionable downstream of the illumination-optical system for illumination by the illumination-light flux when the first mask is not being illuminated with the illumination-light flux; (d) a projection-optical system for receiving illumination light transmitted through the first or second mask from the illumination-optical system and projection-distributing the illumination light to the substrate, the second and third mask patterns being configured relative to the first mask pattern so as to produce, after a total predetermined number of multiple exposures of the multiple-exposure areas of the substrate, a total average intensity of illumination light on the multiple-exposure areas that is substantially equal to a total average intensity of illumination light produced by the one exposure of the first mask pattern on the single-exposure areas of the substrate.

Claim 16

The apparatus of claim 12, wherein each of the second and third mask patterns comprise light-blocking sections and light-transmissive sections, the light-transmissive sections of the third mask pattern being positioned so as to overlap the light-blocking sections of the second mask pattern.

Claim 17

The apparatus of claim 12, further comprising a mask loader for replacing the first mask with the second mask.

Claim 18

The apparatus of claim 12, further comprising an illumination-light source situated upstream of the illumination-optical system.