A method for measuring wafer liquid film middle variant in CMP process

Abstract

A method for measuring intermediate variable of a liquid film under a wafer during CMP process comprises: (1) adding fluorescent material in the polishing slurry, and transferring the fluorescent slurry to the space between the polishing pad of the polisher and the wafer, in order to form a liquid film; (2) starting a laser to irradiate the liquid film so that the liquid film generates fluorescence after the irradiation; (3) the fluorescence generated by the liquid film is transferred to the camera via a filter for fluorescence information collection; (4) carrying out image process on fluorescence image collected by the camera, and calculating to obtain the fluorescence intensity, obtaining thickness of the liquid film according to corresponding relation between the intensity and thickness of the fluorescence, and obtaining the temperature of liquid film according to corresponding curve between the intensity and temperature of the fluorescence, also obtaining the pH value of the liquid film according to corresponding curve of intensity and pH value of the fluorescence. The invention can effectively measure the intermediate variable (such as thickness, temperature, pH value) of a liquid film under a wafer during CMP process.

Description

technical field [0001] The invention relates to the field of laser measurement, in particular to a method for measuring intermediate variables (polishing liquid film thickness, liquid film temperature and liquid film pH) under a wafer in a CMP process. Background technique [0002] With the development of VLSI multilayer interconnection technology, it is necessary to implement multilayer wiring structures on silicon wafers, and each layer requires high global flatness to meet etching requirements. In 1990, IBM Corporation took the lead in proposing the chemical mechanical polishing (CMP, Chemical Mechanical Planarization) global planarization technology, which was successfully applied in the production of 64Mb DRAM in 1991. After that, CMP technology developed rapidly. At present, the research and development work of CMP technology has developed to the whole world, and presents a fierce competition momentum. [0003] Although CMP is considered to be the most effective meth...

AI Technical Summary

Problems solved by technology

[0006] In order to overcome the inadequacy of the existing technology that cannot measure the intermediate variables under the wafer in the CMP process, the present invention provides a method based on LIF technology that can effectively measure the intermediate variables (such as thickness, temperature, and pH value) under the wafer in the CMP process. Measurement method of under-wafer intermediate variables in the CMP process

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