A method of controlling polishing includes polishing a substrate at a first polishing station, monitoring the substrate with a first eddy current monitoring system to generate a first signal, determining an ending value of the first signal for an end of polishing of the substrate at the first polishing station, determining a first temperature at the first polishing station, polishing the substrate at a second polishing station, monitoring the substrate with a second eddy current monitoring system to generate a second signal, determining a starting value of the second signal for a start of polishing of the substrate at the second polishing station, determining a gain for the second polishing station based on the ending value, the starting value and the first temperature, and calculating a third signal based on the second signal and the gain.

An output of an eddy current sensor includes an impedance component. A film thickness measuring apparatus obtains film thickness information from the impedance component. Using a non-linear function between the film thickness information and the film thickness, the film thickness is obtained from the film thickness information. When a resistance component and a reactance component of the impedance component are associated with respective axes of a coordinate system having two orthogonal coordinate axes, the film thickness information is a reciprocal of a tangent of an impedance angle which is an angle formed by a straight line connecting a point on the coordinate system corresponding to the impedance component and a predetermined reference point, and a predetermined straight line.

To specify a trajectory of an eddy current sensor provided on a polishing table of a substrate polishing apparatus, disclosed is a method of identifying a trajectory of an eddy current sensor as seen from a substrate in a substrate polishing apparatus having a polishing table and a polishing head. The method includes: obtaining a sensor output map as three-dimensional data; polishing the substrate; obtaining a profile of the real-time polishing signal as two-dimensional data; and extracting a trajectory having a profile most similar to the profile of the real-time polishing signal as two-dimensional data from the sensor output map as three-dimensional data and identifying the extracted trajectory as a trajectory of the eddy current sensor as seen from the substrate.

A method of chemical mechanical polishing includes bringing a substrate having a conductive layer disposed over a semiconductor wafer into contact with a polishing pad, generating relative motion between the substrate and the polishing pad, monitoring the substrate with an in-situ electromagnetic induction monitoring system as the conductive layer is polished to generate a sequence of signal values that depend on a thickness of the conductive layer, determining a sequence of thickness values for the conductive layer based on the sequence of signal values, and at least partially compensating for a contribution of conductivity of the semiconductor wafer to the signal values.

An apparatus for chemical mechanical polishing includes a support for a polishing pad having a polishing surface, and an electromagnetic induction monitoring system to generate a magnetic field to monitor a substrate being polished by the polishing pad. The electromagnetic induction monitoring system includes a core and a coil wound around a portion of the core. The core includes a back portion, a center post extending from the back portion in a first direction normal to the polishing surface, and an annular rim extending from the back portion in parallel with the center post and surrounding and spaced apart from the center post by a gap. A width of the gap is less than a width of the center post, and a surface area of a top surface of the annular rim is at least two times greater than a surface area of a top surface of the center post.

A conditioner of a chemical mechanical polishing (CMP) apparatus includes a conditioning part to polish a polishing pad, an arm to rotate the conditioning part, and a flexible connector connecting the conditioning part with the arm, the flexible connector being moveable to allow relative movements of the conditioning part with respect to the arm.

A method of controlling polishing includes polishing a stack of adjacent conductive layers on a substrate, measuring with an in-situ eddy current monitoring system a sequence of characterizing values for the substrate during polishing, calculating a polishing rate from the sequence of characterizing values repeatedly during polishing, calculating one or more adjustments for one or more polishing parameters based on a current polishing rate using a first control algorithm for an initial time period, detecting a change in the polishing rate that indicates exposure of the underlying conductive layer, and calculating one or more adjustments for one or more polishing parameters based on the polishing rate using a different second control algorithm for a subsequent time period after detecting the change in the polishing rate.

Data received from an in-situ monitoring system includes, for each scan of a sensor, a plurality of measured signal values for a plurality of different locations on a layer. A thickness of a polishing pad is determined based on the data from the in-situ monitoring system. For each scan, a portion of the measured signal values are adjusted based on the thickness of the polishing pad. For each scan of the plurality of scans and each location of the plurality of different locations, a value is generated representing a thickness of the layer at the location. This includes processing the adjusted signal values using one or more processors configured by machine learning. A polishing endpoint is detected or a polishing parameter is modified based on the values representing the thicknesses at the plurality of different locations.

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.

A chemical mechanical polishing apparatus includes a platen to support a polishing pad, the platen having a recess, a flexible membrane in the recess, and an in-situ vibration monitoring system to generate a signal. The in-situ acoustic monitoring system includes a vibration sensor supported by the flexible membrane and positioned to couple to an underside of the polishing pad.