Alignment system for photolithographic device and photolithographic device applying same

Abstract

The invention provides an alignment system for a photolithographic device, which is used for alignment according to alignment marks on a wafer. The alignment marks are three-period phase grating marks and comprises three gratings with different periods, namely, a first grating, a third grating and a second grating; and an optical deflection structure is arranged on a spectrum surface of an imaging module and used for deflecting positive and negative primary diffracted wave bundles of the third grating in the Y direction of the alignment mark in the Y direction to the X direction or deflectingpositive and negative primary diffracted wave bundles of the third grating in the X direction of the alignment mark in the X direction to the Y direction. The alignment system for the photolithographic device utilizes the optical deflection structure to deflect the small-period diffracted wave bundles in the Y (or X) direction to the X (or Y) direction so as to realize alignment scanning in the two directions, improve the energy utilization rate and enable obtained alignment signals to have no obvious inflexion points.

Description

technical field [0001] The present invention relates to an alignment system, and in particular to an alignment system for a lithographic apparatus. Background technique [0002] The photolithography apparatus in the prior art is mainly used in the manufacture of integrated circuits (ICs) or other micro devices. A critical step in a lithographic setup is the alignment of the mask to the wafer. After the first layer of mask pattern is exposed on the wafer, it is removed from the device. After the wafer is processed in a related process, the exposure of the second layer of mask pattern is carried out, but in order to ensure that the second layer of mask pattern and subsequent mask pattern Precise positioning of the image relative to the image of the exposed mask pattern on the wafer requires precise alignment of the mask and wafer. IC devices manufactured by photolithography technology require multiple exposures to form multilayer circuits in the wafer. For this reason, an al...

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Problems solved by technology

Corresponding reference signs are grouped into eight branches, see Figure 7A , which will bring many disadvantages: the alignment mark and the corresponding reference mark occupy a relatively large space, which makes the energy utilization rate of the light source low, and factors such as lithography process and wafer deformation have a relatively large impact on the alignment accuracy; alignment mark diffraction When the interference image of the beam is scanned with the reference mark, the obtained alignment scan signal intensity has an obvious inflection point (see Figure 7B ), this kind of alignment scanning signal is not conducive to related signal processing such as AGC gain in the later stage; because the middle branch of the reference mark scans in one direction when the reference mark (see Figure 7A )G3-a and G3-b (or G6-a and G6-b) jointly scan the interference image of a marked grating diffracted beam, and no light can enter the transmission fiber and photodetector behind the reference mark in the blank area between the two branches , so that the intensity and signal-to-noise ratio of the alignment scanning signal are very low, and it will cause the interference image of the two reference mark branches G3-a and G3-b (or G6-a and G6-b) relative to the alignment mark diffracted beam The phase mismatch problem occurs, which is not conducive to the alignment of the alignment mark and signal processing; the two small period reference marks in the same direction are required to be as small as possible when the energy of the alignment signal is sufficient, but at the same time it brings the transmission behind the reference mark Smaller fiber diameter and difficulty coupling spatially to reference markers

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