On-line testing apparatus of projection objective

Abstract

The invention discloses an on-line detection device used for the projection objective lens of a lithography machine. The on-line detection device of the present invention includes a light source for generating light beams, an illumination system for converting the light source to a specific illumination mode for a reticle, a mask table equipped with a pinhole reticle and precisely positioned, and a projection for imaging the pattern of the mask The objective lens, the workpiece table carrying the substrate, and the optical detection element for detecting the outgoing beam of the projection objective lens, wherein the light source and the illumination system also include an optical path separation element, which separates the light source into two parts of the light beam for reference and measurement and The reference light wavefront entrance and the measurement light wavefront entrance respectively emitted to the optical detection element. The objective lens detection device of the invention can accurately measure the wavefront error, magnification, distortion and field curvature of the objective lens, and can reduce the size of the optical detection element, and has simple manufacture, high detection accuracy 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

Images