Optical system for focal plane detection in projection lithography

Abstract

The invention relates to an optical system for focal plane detection in projection lithography. A focus detection mark and a projection imaging system are arranged between a lighting system and a multi-reflection prism; a plane to be detected is located between the multi-reflection prism and a reflector; a focus detection mark amplification system is located between the reflector and a detector; the projection imaging system is matched with the lighting system to provide a lighting beam for lighting the focus detection mark; the multi-reflection prism is used for splitting the incident beam of the lighting system for lighting the focus detection mark into two or more detection beams with different positions; the focus detection mark can mark the position and form an image of each detection beam on the surface of the plane to be detected through the projection imaging system and multi-reflection prism; the detection beams reflected by the plane to be detected is amplified by the focus detection mark amplification system and is incident to the detector; and the detector detects the position of the reflected images amplified by the optical amplification system so as to detect the focal plane position and the focal plane inclination of a lithographic projection objective lens.

Description

technical field [0001] The invention relates to an automatic focal plane detection system, which is a technique for measuring the position movement of an imaging plane through an optical triangulation method. Background technique [0002] Photolithography device (lithography machine) is one of the important equipment for the production of large-scale integrated circuits. The projection lithography machine can image the pattern on the mask plate to the object to be processed (such as a silicon wafer, etc.) in a certain proportion through the imaging exposure device. The silicon wafer here refers to all exposed objects, including substrates, coatings and light Engraving etc. During the exposure process, it is necessary to keep the corresponding surface of the processing object (such as a silicon wafer) within the focal depth range of the exposure device. For this reason, the projection lithography machine adopts a focusing and leveling measurement system (focal plane detecti...

AI Technical Summary

Problems solved by technology

The measurement position of the above-mentioned focusing and leveling measurement system is a single position, that is, it can only test the average position information of a certain point or a small area on the processing object

In order to realize the two functions of focusing and leveling measurement required by the projection lithography machine, it is necessary to use several sets of focal plane detection systems (such as: Overlay and field leveling in wafersteppers using an advanced metrology system, SPIE Vol.1673) or in a Several marks are used in the system (such as US patent: US5191200), which makes the entire focusing and leveling measurement system very redundant

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