Aligning system for photolithography equipment and its alignment method and photolithography equipment

Abstract

The invention provides an aligning system used for a lithography device, comprising a plurality of position detectors comprising a global typed position detector and a local typed position detector which are integrated in an aligning system; the whole system has compact structure, strong process adaptability and can generate the aligning signal with high sensitiveness and high signal-to-noise ratio. The aligning method can select different position detectors to carry out the aligning detection under different processing situations; when both of two position detectors can comply with the aligning requirements, the weighted processing of the aligning position information gained by the two position detectors can be carried out so as to gain final marked central position. The aligning system uses the same aligning marks when different position detectors are used for aligning detection; therefore, the area occupying of wafers can be saved, and the position detector can be freely changed inthe aligning process by the user.

Description

technical field [0001] The invention relates to photolithography devices in the field of integrated circuit or other micro-device manufacturing, in particular to an alignment system and its alignment technology. Background technique [0002] Photolithography equipment is mainly used in the manufacture of integrated circuits IC or other micro-devices; through lithography equipment, multi-layer masks with different mask patterns are sequentially imaged on a wafer coated with photoresist under precise alignment; currently There are two types of lithography equipment, one is a stepper lithography equipment, the mask pattern is imaged on one exposure area of ​​the wafer in one exposure, and then the wafer is moved relative to the reticle to move the next exposure area to the mask pattern and projection objective Below, the mask pattern is exposed on another exposure area of ​​the wafer again, and this process is repeated until all exposure areas on the wafer have an image of the ...

AI Technical Summary

Problems solved by technology

[0006] This global alignment system can partially suppress the signal attenuation effect caused by destructive interference through dual-wavelength illumination; however, since only two visible wavelength laser sources are used, in fact, the signal attenuation caused by destructive interference must be completely eliminated The problem needs to use at least 4-5 illumination wavelengths, and the absorption of low-k value dielectric materials in the visible spectrum range will cause the attenuation of the alignment signal intensity, thereby affecting the alignment accuracy; when the alignment mark is asymmetrically deformed due to process influence When , the asymmetric deformation of the alignment signal will directly lead to the deviation of the alignment position. This effect can be reduced by detecting the multi-order diffracted light of the alignment mark, including the high-order diffracted light. However, the wedge array Or a wedge group (some wedges also need to be drilled) to achieve the separation and coherent imaging of multi-level diffracted light, and the consistency of the surface shape and wedge angle processing of two wedges with the same order of positive and negative refraction The requirements are very high; and the wedge plate group and the precise position drilling on the wedge plate make the requirements for manufacturing, assembly and adjustment very high, and the specific implementation is difficult and expensive

[0007] The situation of another kind of prior art (referring to U.S. invention patent, patent number: US5477057, title of invention: Off axis alignment system for scanning photography), a kind of partial alignment system AXIOM that SVGL company adopts, this alignment system adopts non- Coherent broadband illumination light source, with a wavelength of 475nm-650nm, projects an "X"-shaped illumination spot onto the wafer surface; during the scanning process of the workpiece table, the "X"-shaped illumination spot scans the edges of the alignment mark grating lines in sequence (the alignment mark is ±45 " / " and "\" shaped gratings tilted at a degree angle), diffraction and reflection occur on the edge, and pass through the diaphragm baffle with five apertures on the pupil plane (the central area is the bright field area, and the edge The four areas are dark field areas; the opaque area between the bright field and the dark field is the light-blocking zone;) Simultaneously detect the bright field signal and the dark field signal, and separate the "left / right" dark field signal; the resulting signal is installed The optical fiber bundle behind the diaphragm baffle is received and transmitted to the detector, and the position information of the alignment mark is obtained according to the dark field signal at the edge of the marked grating and the bright field signal at the non-edge; however, when the "X" illumination spot scans alone When the +45 degree mark, another illumination spot in the direction of -45 degree will also scan the +45 degree mark, which will introduce background noise, thereby affecting the signal-to-noise ratio of the dark field signal; more importantly, when the alignment mark is caused by process influence When the phase depth becomes smaller (shallow groove marks), the attenuation of the contrast of the left / right dark field signal will reduce the signal-to-noise ratio of the alignment signal, which directly leads to the deviation of the alignment position; in addition, the broadband illumination source can automatically compensate for the thin film effect, It is not sensitive to the marking film structure, but the disadvantage is that the brightness is insufficient, and it cannot provide enough illumination for the shallow groove mark to detect the weak diffracted light signal

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