On-line testing apparatus of projection objective

Abstract

The invention discloses an on-line detecting device of projective object lens of photo-etching machine, which comprises the following parts: light source to generate beam, illuminating system to converse light source into specific illuminating pattern of mask, mask platform to embark pinhole mask board to locate precisely, projective objective lens of the imaging pattern of mask, working platform to embark the base, optical detecting element to detect the ejected beam of projective objective lens, wherein the light source and illuminating system also contains an optical-path separating element, which separates the light source into reference and measurement beams to be ejected to the front inlet of reference wave and measurement wave of optical detecting element. The invention can measure the wave front error, magnification ratio, distortion and field curvature of objective lens precisely, which reduces the size of optical detecting element with simple preparation, high precision and convenient operation.

Description

technical field [0001] The invention relates to an on-line detection device of a projection objective lens, in particular to an on-line detection device of a projection objective lens of a photolithography machine in the manufacturing process of micro devices such as semiconductor elements and liquid crystal display elements. Background technique [0002] In recent years, in the field of semiconductor lithography, the projection lithography technology has been continuously improved, and the lines have been advanced in a finer direction. At present, the critical size of the chip has reached the lithography resolution capability of 90nm to 65nm. The imaging quality of the optical projection objective lens in the lithography system is a key factor affecting the resolution of lithography. The projection objective lens can achieve very high quality when it is designed, but the optical quality of the objective lens will be affected in the process of optical processing, assembly an...

AI Technical Summary

Problems solved by technology

However, the main disadvantages of this online detection objective lens method are: 1. It is necessary to introduce an additional light source for measurement; 2. The Hartmann sensor is used to sample the wavefront. Due to manufacturing limitations, the Hartmann space sampling rate cannot be too high, so it cannot Measuring Advanced Aberrations of Projection Objectives

3. CCD manufacturing requirements are strict, since the accuracy of the Hartmann sensor is directly determined by the center position of the spot on the CCD, if there is a size error in the CCD manufacturing itself, this will inevitably lead to a position error of the center point

4. The manufacturing of the array lens is difficult, and the optical error it introduces affects the positioning accuracy of the spots

5. In addition, in order to measure the accuracy, it is necessary to increase the focal length of the array lens, which will also increase the size of the Hartmann sensor and CCD

6. The algorithm for determining the position of the spot is complex, and its model is difficult to determine due to the influence of many factors such as the aberration of the CCD characteristic array lens

In addition, US6573997 describes a method of using gratings to achieve phase-shift point diffraction interference to detect objective lenses. This method can effectively measure objective aberrations close to the diffraction limit, but it needs to use two gratings to achieve light splitting. , the fabrication and assembly of the grating are very difficult, and it is not suitable for integration on the lithography machine. In addition, this method cannot achieve phase shift at the same time, so the light source needs to be precisely controlled

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