| 摘要 |
Apparatus and method for measuring the aberration of a lens in reduction projection exposure apparatus, such as used in photolithography. A test mask has at least first and second diffraction grating patterns having arrays of large blocks and micro-patterns respectively and are spaced by a predetermined interval (see figures 1 and 3). The patterns on the test mask, or reticule, are projected through the lens to be tested and are transferred onto a photosensitive substrate 103, 104. The interval d between the at least two grating arrays 1, 2 is measured by scanning the substrate with a coherent light source, 101 such as a laser, having a diffractable wavelength. Distortion of the transferred patterns including a positional shift of an image point due to lens aberration is thus measured. |
