Pad conditioner cut rate monitoring
An apparatus for chemical mechanical polishing includes a platen having a surface to support a polishing pad, a carrier head to hold a substrate against a polishing surface of the polishing pad, a pad conditioner to hold a conditioning disk against the polishing surface, an in-situ polishing pad thickness monitoring system, and a controller. The controller is configured to store data associating each of a plurality of conditioner disk products with a respective threshold value, receive an input selecting a conditioner disk product from the plurality of conditioner disk products, determine a particular threshold value associated with the selected conditioner disk product, receive a signal from the monitoring system, generate a measure of a pad cut rate from the signal, and generate an alert if the pad cut rate falls beyond the particular threshold value.
1 . An apparatus for chemical mechanical polishing, comprising:
a platen having a surface to support a polishing pad;
a carrier head to hold a substrate against a polishing surface of the polishing pad;
a pad conditioner to hold a conditioning disk against the polishing surface;
an in-situ electromagnetic induction polishing pad thickness monitoring system comprising a sensor having a magnetic core; and
a controller configured to receive a signal from the in-situ electromagnetic induction polishing pad thickness monitoring system, generate a measure of a pad cut rate from the signal, and determine a measure of variability of the pad cut rate over time from the signal, wherein the pad cut rate is indicative of an effectiveness of the conditioning disk in conditioning the polishing pad.
2 . The apparatus of claim 1 , wherein the controller is configured to generate an alert if the measure of variability exceeds a threshold.
3 . The apparatus of claim 1 , wherein the controller is configured to determine a measure of variability by calculating a standard deviation of the pad cut rate.
4 . The apparatus of claim 3 , wherein the controller is configured to calculate the standard deviation in a running window of measurements.
5 . The apparatus of claim 4 , wherein the running window of measurements is a running window of the last N measurements, wherein N is 3 to 30.
6 . The apparatus of claim 5 , wherein N is 5 to 10.
7 . The apparatus of claim 1 , wherein the magnetic core is held on the pad conditioner so as to generate a magnetic field to induce a current in the platen.
8 . The apparatus of claim 1 , wherein the pad conditioner comprises an arm extending over the platen and the magnetic core is supported on the arm of the pad conditioner.
9 . The apparatus of claim 1 , wherein the controller is configured to generate an alert if the pad cut rate falls beyond a threshold value.
10 . The apparatus of claim 1 , wherein the controller is configured to calculate the pad cut rate by applying a predictive filter to a sequence of pad thickness measurements of the signal, and calculating the pad cut rate using the predictive filter.
11 . The apparatus of claim 1 , wherein the magnetic core is held in a recess in the platen so as to generate a magnetic field to induce a current in the conditioning disk.
12 . The apparatus of claim 1 , wherein the magnetic core is held in a recess in the platen so as to generate a magnetic field to induce a current in a conductive body above the polishing pad.
13 . The apparatus of claim 12 , wherein the conductive body comprises the conditioning disk.