Apparatus for endpoint detection during polishing

Abstract

An apparatus for endpoint detection during polish, being used to monitor the surface polishing status of a polishing surface of a workpiece, is disclosed, which comprises: a probe, being positioned above the workpiece by a height; and at least a sensing element, being disposed on the probe at a position corresponding to the polishing surface, capable of sensing the thickness variation of the workpiece during a polishing process as it is performing a surface dynamic scan upon the workpiece in rotating while it is being driven to proceed a linear motion of displacement. Preferably, the sensing element can be a device selected from the group consisting of an optical sensor, an eddy current sensor and the combination of the two for carrying out optical detection and magnetic flux detection. It is noted that the apparatus for endpoint detection of the invention not only is advantaged in its all-zone detection ability, but also it has enhanced detection accuracy with respect to different metal layer of different thickness.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an apparatus capable of monitoring the thickness of a workpiece, and more particularly, to an apparatus having a sensing element disposed on a probe thereof while enabling the sensing element to perform a linear movement, which is capable of monitoring and measuring the surface polishing status of a workpiece during a polishing process. BACKGROUND OF THE INVENTION [0002] It is known that miniaturization is the strategy to success, which requires small, high performance, versatile, highly reliable and inexpensive microstructured components, the structure of microstructured component has becoming more and more complex. As manufacturers reduce the size of integrated circuit (IC) components to fit more components on each IC chip and as the substrate of IC manufacturing is getting larger, there is more going on in the IC fabrication process itself than a simple reduction in scale. That is, the demanding for higher inspection ...

AI Technical Summary

Benefits of technology

The present invention provides an apparatus for endpoint detection during polishing. The apparatus includes a probe and a sensing element that can detect the thickness variation of a workpiece during the polishing process. The sensing element can be an optical sensor, an eddy current sensor, or a combination of both. The apparatus can be used to monitor the surface polishing status of a workpiece and provide accurate detection of different metal layers of different thickness. The sensing element can generate a magnetic field or detect the intensity of magnetic field generated on the workpiece. The apparatus can also include an optic sensor for receiving light beams reflected from the workpiece. The signal integrating unit can integrate the signals received from the sensing element and output a sensing signal. The control unit can evaluate the surface polishing status of the workpiece based on the sensing signal.

Problems solved by technology

It is known that miniaturization is the strategy to success, which requires small, high performance, versatile, highly reliable and inexpensive microstructured components, the structure of microstructured component has becoming more and more complex.

That is, the demanding for higher inspection precision and better accuracy of each manufacturing process are required.

(2) The EPDs used in the prior methods are all being fixed to a specific position that the area of detection on a large-sized wafer are limited and thus they can only be used as local detectors so that the accuracy of detection acquired thereby is not preferred since the overall thickness variation of the large-sized wafer can not be detected and measured by a local EPD.

It is noted that the planarity of the device surface seen in FIG. 2B is not ideal enough for the next processing step to be performed thereon, so that a polishing process is required to create a surface of enough planarity of flatness as seen in FIG. 2C.

However, since the prior-art EPD can only detect a portion of the substrate wafer while it is being used for determining the endpoint of a polishing process, a portion of the wafer might be over-polished while another portion thereof might be under-polished such that the thickness of the target layer is not uniform.

Furthermore, It is known that all the prior-art polishing processes are dependent on the calculation of total thickness variation (TTV) which used a designated base level as reference level that can cause error while the planarity of a workpiece is not sufficient or the workpiece is not being positioned properly.

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