Method of detecting alignment shift

Abstract

The invention provides a method for detecting alignment deviation, comprising forming a control gate polysilicon layer on the isolation structure in the substrate of the wafer test area, and then forming a dielectric layer on the control gate polysilicon layer, and forming a dielectric layer on the dielectric layer Form two openings with different cross-sectional widths, wherein the two openings cover the control gate polysilicon layer with a smaller cross-sectional width, and finally remove the control gate polysilicon layer below the dielectric layer to form the first control grid and the second control grid, the cross-sectional widths of the first control grid and the second control grid are not equal, the length and material of the first control grid and the second control grid are all the same, and the ratio of their resistances is inversely proportional to the section width. By detecting the resistance of the first control grid and the second control grid, it can effectively reflect the floating gate of the flash memory unit and the control Check whether the grid has shifted, and improve the online monitoring ability of the product.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for detecting alignment deviation. Background technique [0002] With the rapid development of portable electronic devices, the requirements for data storage are getting higher and higher. Semiconductor memory for storing data is classified into volatile memory and nonvolatile memory. Among non-volatile memories, flash memory (flash memory) has become an extremely important device due to its high chip storage density and better process adaptability. [0003] When self-alignment technology is used to form flash memory cells, the exposure process is often used. Due to the alignment deviation between different wafers or two-layer exposures at different positions of a single wafer in the exposure process, the exposure of the floating gate is relative to the control gate. Exposure will inevitably produce alignment shift, and the ordinary exposure process is limite...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a method for detecting alignment offset, so as to solve the problem that the existing technology cannot effectively detect whether there is an offset between the floating gate and the control gate of the flash memory unit.

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