Methods of Silicon Wafer Pre-Alignment

Abstract

The invention provides a silicon chip pre-alignment method, which mainly improves the precision and efficiency of the silicon chip pre-alignment from several aspects such as optimization control and error compensation. Use the step-by-step drop method to initially locate the gap, determine its approximate position, and use the benchmark method to calculate the position of the lowest point of the gap; compensate the data of the gap collection points, and use the matrix fitting method to calculate the centroid of the silicon wafer, to a large extent The accuracy of the centroid calculation is improved, and only one sampling data of the CCD linear sensor can be used for precise positioning, which greatly improves the accuracy and efficiency of pre-alignment. In addition, the pre-alignment error is corrected to correct the silicon wafer centroid calculation error, so as to further improve the pre-alignment accuracy.

Description

technical field [0001] The invention relates to a silicon chip pre-alignment method, in particular to a silicon chip pre-alignment method applied in a photolithography machine. Background technique [0002] The photolithography machine is an indispensable tool in the manufacturing of microelectronic devices, and because the field of view of the photolithography machine is very small, before the silicon wafer is transferred to the photolithography machine for exposure, the silicon wafer must be pre-aligned, so that the transmission The silicon wafer on the exposure table is within the field of view of the lithography machine, so pre-alignment of the silicon wafer is an important part of the silicon wafer exposure performed by the lithography machine. Specifically, pre-alignment is a precise positioning for transporting the silicon wafer to the workpiece table for exposure, and the pre-alignment directly affects the exposure accuracy of the silicon wafer and the working effici...

AI Technical Summary

Problems solved by technology

[0006] Before locating the notch on the silicon wafer, the methods commonly used for rough positioning of the notch include: cross-correlation detection method, cosine curve fitting method, and edge change rate method, but none of them are ideal. For example, the edge change rate method is used to rough the gap Positioning has great limitations. For example, in Chinese patent: CN1787200A, the included angle is calculated for three adjacent sampling points, and an appropriate threshold value is required to be set. This threshold value is determined by empirical methods. The situation is very unstable. This method requires that the edge data of the silicon wafer collected by the CCD must be evenly distributed, and the amplitude of the adjacent data collected cannot change too much. If the pre-alignment of the silicon wafer is not very circular , the experiment proves that due to the uneven rotation speed of the rotary table, the control program written by the algorithm using this idea is prone to collapse, and the center of the lowest point of the silicon wafer gap cannot be found or found incorrectly, which will have an adverse effect on the orientation of the silicon wafer. A good impact will eventually lead to a significant reduction in the overall performance of the lithography machine manufacturing equipment assembly line and the production yield

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