Dual detection method for end point in chemical mechanical polishing
First Claim
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1. A method for detecting an end point in a chemical mechanical polishing (CMP) process comprising the steps of:
- providing a CMP apparatus contained in an enclosure;
mounting an acoustical sensor in said enclosure;
initiating a CMP process on a semiconductor wafer for removing an uppermost coating layer;
monitoring an acoustical emission generated by said CMP process and recording a volume of the emission; and
stopping said CMP process when the volume of the acoustical emission changes by at least 30% from its initial volume.
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Abstract
A dual detection method for end point in a chemical mechanical polishing process is described. The dual detection method utilizes both an optical detection device and an acoustical detection device. The acoustical detection device may also be used independently in certain applications without the optical detection device. The acoustical detection device determines an end point and stops the CMP process when a volume of the acoustical emission changes by at least 30% from its initial volume, or preferably changes by at least 50% from its initial volume.
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Citations
20 Claims
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1. A method for detecting an end point in a chemical mechanical polishing (CMP) process comprising the steps of:
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providing a CMP apparatus contained in an enclosure;
mounting an acoustical sensor in said enclosure;
initiating a CMP process on a semiconductor wafer for removing an uppermost coating layer;
monitoring an acoustical emission generated by said CMP process and recording a volume of the emission; and
stopping said CMP process when the volume of the acoustical emission changes by at least 30% from its initial volume. - View Dependent Claims (2, 3, 4, 5)
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6. A chemical mechanical polishing apparatus equipped with an acoustical end point detection device comprising:
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a polishing pad holder for holding a polishing pad thereon;
means for rotating said polishing pad holder;
a sample holder for holding a sample to be polished thereon;
means for rotating and traversing said sample holder on said polishing platen;
an enclosure for enclosing said polishing pad holder and said sample holder; and
an acoustical sensor mounted in said enclosure for sensing acoustically an end point of the polishing process as the point when a change in acoustical emission of at least 30% occurs. - View Dependent Claims (7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20)
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13. A dual detection method for an end point in a chemical mechanical polishing (CMP) process comprising the steps of:
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providing a CMP apparatus contained in an enclosure, said CMP apparatus comprises a polishing pad holder equipped with an optical projector and a sensor therein for projecting and receiving an optical signal to and from a surface of a sample being polished through a window in said polishing pad for determining an end point of said CMP process;
mounting an acoustical sensor in said enclosure for sensing and recording an acoustical signal generated by said CMP process;
initiating a CMP process on said sample for removing an uppermost coating layer;
determining an end point of the CMP process upon the occurrence of at least one of the two events;
the optical signal received from said sample surface being indicative of an interface between said uppermost coating layer and an underlying layer; and
the acoustical emission generated by said CMP process changes by at least 30% of its initial value.
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Specification