Apparatus and method for measuring wave aberration

Abstract

The invention discloses a wave aberration measurement device and a wave aberration measurement method. The wave aberration measurement device comprises a light source, an illuminating system, an object plane module and an image plane detecting unit, wherein the object plane module comprises an object plane grating and an object plane level selection plate, the image plane detecting unit comprises an image plane grating, an image plane level selection plate and a detector, and the object plane grating and the image plane grating both adopt a binary phase shift grating. The object plane grating and the image plane grating both adopt the binary phase shift grating, wherein zero-level light does not exist in diffracted light, only positive / negative 1-level light exists in the diffracted light, the light intensity used for measuring is improved, the filtering effect of the 0-level diffracted light is not taken into consideration for the object plane level selection plate, and the process difficulty is reduced; the object plane module uses the object plane grating and the object plane level selection plate, the transmittance of the object plane grating is much larger than that of the initial pinhole, the time for acquiring an image plane is shortened, the signal intensity is improved, and the measurement speed and the measurement accuracy are improved.

Description

technical field [0001] The invention relates to the field of integrated circuit manufacturing, in particular to a wave aberration measuring device and method. Background technique [0002] The wave aberration of the projection objective lens is a key factor affecting the imaging quality of the lithography machine. For the wave aberration of the projection objective lens of high-resolution lithography machine, the method of interference can be used for measurement. The cross grating transverse shearing interferometer is a commonly used method of using the interference principle to detect the wave aberration of the projection objective lens. Its principle is as follows: figure 1 As shown, light passes through the initial pinhole 1 and is diffracted to form an aberration-free spherical wave. After the spherical wave passes through the objective lens 2 to be tested, its wavefront will carry the wave aberration of the objective lens 2 to be tested. A binary grating 3 is placed...

AI Technical Summary

Problems solved by technology

[0005] 2. In order to produce an ideal spherical wave, the size of the small hole should not be too large, so that the light transmittance is low and the contrast of the image surface measurement is reduced;

[0006] 3. The light beams participating in the interference converge at different points on the image plane, making the interference area smaller, increasing the measurement noise and reducing the accuracy

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