Wafer surface metal film thickness measuring method

Abstract

The invention provides a wafer surface metal film thickness measuring method, which comprises the following steps of: acquiring a constant parameter, namely acquiring a propagation time difference of sound waves in a metal film on the surface of a wafer at two preset points on the surface of the wafer, acquiring a surface height difference between the two preset points, and taking a ratio of the height difference to the time difference as the constant parameter; and measuring the thickness of the metal film on the surface of the wafer, namely acquiring propagation time of sound waves in the metal film on the surface of the wafer at a measurement point on the surface of the wafer, and taking the product of the time and the constant parameter as the thickness of the metal film at the measurement point. According to the measuring method, the thickness of the metal film on the surface of the wafer can be monitored in real time, the measurement accuracy is high, the productivity is greatly improved, and the cost is saved; moreover, the surface height difference of the two preset points can be obtained without damaging the wafer, the wafer is prevented from being damaged, and a nondestructive measurement method is provided.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a method for measuring the thickness of a metal film on a wafer surface. Background technique [0002] During the wafer production process, various film layers, including metal films, are formed on the surface. Among them, in the metal electroplating process for forming the metal film, the metal growth rate of the dense region and the loose region of the base structure differs greatly. The thickness of the dense region is more than twice the thickness of the loose region, which poses a great challenge to the subsequent metal grinding process. If the difference in the thickness of the metal film in the dense area and the loose area of ​​the wafer is too large, the metal film on the surface of the loose area has been completely ground off during the metal grinding process, while the metal film on the surface of the dense area has not been removed. There are still metal res...

AI Technical Summary

Problems solved by technology

Since the thickness of the metal film cannot be monitored in real time before the metal grinding process, in order to make the thickness of the metal interconnection in the loose area and the dense area after the metal grinding process meet the requirements, the electroplating thickness will be increased when the metal is electroplated, and the thickness will be increased. , the electroplating time increases accordingly, the output rate of the electroplating equipment decreases, the material consumption increases, and the cost increases; at the same time, the thickness of the electroplating increases, and in the subsequent metal grinding process, the output rate of the metal grinding equipment decreases, the amount of grinding fluid used increases, and the production capacity decreases. cost increase

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