Cmp apparatus and method of polishing wafer using cmp

Abstract

A CMP apparatus is provided with a replaceable polishing pad, a film thickness sensor, and a polishing control unit for switching polishing conditions in response to a fact that an output value from the film thickness sensor has exceeded a threshold value. The polishing control unit has a memory unit for storing a threshold value corresponding to the thickness of a new polishing pad when the polishing pad is replaced. The memory unit also store conversion information that shows the relationship between the output value of the film thickness sensor and the thickness of the polishing pad when the thickness of the film being polished is constant. The polishing control unit accesses the conversion information, obtain the output value of the film thickness sensor that corresponds to the thickness of the new polishing pad, and record the output value as the threshold value.

Description

TECHNICAL FIELD[0001]The present invention relates to a CMP (chemical mechanical polishing) apparatus and a method of polishing a semiconductor wafer using the CMP, and more particularly relates to a method for detecting timing for switching polishing speed.BACKGROUND OF THE INVENTION[0002]CMP is an important technique in manufacturing semiconductor devices. Semiconductor integrated circuit chips are manufactured by forming conductive layers, insulating layers, or other thin film layers in a prescribed order on a wafer, patterning the layers depending on need by photolithography and etching, and cutting and separating each chip on the wafer after forming all layers. When there are convexities and concavities or steps in the substrate when a film is formed, the thickness of the film formed on the substrate will be thin in parts and step coverage will worsen, causing lower yield and other problems. Also, problems occur in that focus during exposure is not fixed and precise patterns ca...

AI Technical Summary

Benefits of technology

"The present invention provides a CMP apparatus and a wafer polishing method using CMP that can maintain a constant film thickness during high-speed polishing even if the polishing pad fluctuates. This is achieved by a CMP apparatus that includes a film thickness sensor, a polishing control unit, and a memory unit that stores a threshold value for the output of the film thickness sensor when the polishing pad is replaced or when a reference wafer is set. The polishing control unit measures the thickness of the film being polished and switches polishing conditions accordingly to ensure precise timing and improved throughput while preventing erosion."

Problems solved by technology

When there are convexities and concavities or steps in the substrate when a film is formed, the thickness of the film formed on the substrate will be thin in parts and step coverage will worsen, causing lower yield and other problems.

Also, problems occur in that focus during exposure is not fixed and precise patterns cannot be transferred because convexities and concavities appear in upper layers due to the effect of the lower patterned layers.

However, when tungsten (W), copper (Cu), titanium nitride (TiN) or another metal film is polished at high speed, there is a problem in that erosion increases.

Therefore, there is a problem in that CMP throughput is reduced.

Since the remaining film becomes thin when the polishing pad is thin, quality degradation is liable to occur due to erosion and the like.

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