Apparatus and method for focal plane change measurement

Abstract

The invention provides an apparatus and a method for focal plane change measurement. The measurement method comprises the following steps of entering a reference state, calibrating a position of a reference exposure focal plane, updating inclination of a cornerstone relative to the reference exposure focal plane, aligning a reference mask to obtain a reference alignment focal plane change amount and calculate a position of the reference alignment focal plane, measuring the height and a tilt value of a reference leveling point of a workpiece table datum plate by using a focus and level sensor when the workpiece table datum plate moves to the reference position vertically; starting an exposure process, calculating a drift distance of zero plane of the focus and level sensor before wholly leveling the base; aligning a real mask, and calculating a real alignment focal plane change amount to obtain a position of the real alignment focal plane, thereby guaranteeing that the base is always at an optimum focal plane during the exposure.

Description

technical field [0001] The invention relates to the field of photolithography, and in particular to a focal plane variation measuring device and method. Background technique [0002] The lithography device is mainly used in the manufacture of integrated circuits IC or other micro devices. The lithography device exposes through the projection objective lens and transfers the designed mask pattern to the photoresist. As the core component of the lithography device, the object of the projection objective lens The position of the surface and the mirror has an important influence on the image quality of lithography. The purpose of the projection lithography machine is to clearly image the pattern on the mask on the substrate (silicon wafer) coated with photoresist. To achieve this goal, it must be ensured that the exposure area on the substrate is vertically located at the best focal plane of the projection objective lens ( plane with the best exposure quality). [0003] The be...

AI Technical Summary

Problems solved by technology

[0005] The present invention mainly aims at the situation that the mask alignment cannot be controlled by the focusing and leveling sensor, and the zero plane of the vertical measurement sensor of the workpiece table is set to be constant, even if it changes, it will be superimposed on the drift of the focusing and leveling zero plane The idea of ​​focal plane change measurement is to obtain the drift of the zero plane of the focusing and leveling sensor and the change of the focal plane in real time through a series of measurements, and then compensate the zero plane of the focusing and leveling sensor on the basis of the original exposure focal plane before exposure The amount of drift and the change of the focal plane, so as to obtain the position of the latest best focal plane, and ensure that the focal plane is always the latest focal plane during exposure

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