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 magnetic element for strengthening a magnetic field formed in an object and an eddy current sensor using the magnetic field are provided. The eddy current sensor includes a bottom face portion which is a magnetic body, a magnetic core portion provided at the middle of the bottom face portion and a peripheral wall portion provided on the periphery of the bottom face portion. The eddy current sensor further includes an excitation coil disposed on an outer periphery of the magnetic core portion and capable of generating a magnetic field and an excitation coil disposed on an outer periphery of the peripheral wall portion and capable of generating a magnetic field.

A polishing pad is held using a polishing table. The polishing table is driven to rotate using a first electric motor. The top ring for holding a semiconductor wafer and pressing the top ring against a polishing pad is driven to rotate by a top ring motor. The top ring is held by the swing arm. The swing arm is made to swing around a swing center on the swing arm by a swing shaft motor. A first output is generated by detecting a current value of the swing shaft motor. While polishing the semiconductor wafer by causing the semiconductor wafer to swing around the swing center on the swing arm, a change of a frictional force between the polishing pad and the semiconductor wafer is detected by increasing a change amount of the first output.

A polishing process apparatus includes a carrier configured to support an object, a platen provided below the carrier and configured to accommodate at least one eddy current sensor, the at least one eddy current sensor including a coil configured to output an eddy current, a power supply circuit configured to supply power to the coil and a voltage detection circuit connected to the coil and configured to detect raw voltage data, a polishing pad on an upper surface of the platen, and a controller configured to acquire first data by receiving the raw voltage data from the voltage detection circuit a plurality of times while a polishing process is performed on the object, acquire second data by sequentially applying a first filter and a second filter to the first data, the first filter being different from the second filter and measure a thickness of a target layer included in the object based on the second data.

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.

A polishing method capable of improving a spatial resolution of a film-thickness measurement without changing a measuring cycle of a film-thickness sensor and without increasing an amount of measurement data is disclosed. The polishing method includes: rotating a first film-thickness sensor and a second film-thickness sensor together with a polishing table, the first film-thickness sensor and the second film-thickness sensor being located at the same distance from a center of the polishing table; causing the first film-thickness sensor and the second film-thickness sensor to generate signal values indicating film thicknesses at measurement points on a surface of a substrate, while a polishing head is pressing the substrate against a polishing pad on the rotating polishing table, the measurement points being located at different distances from a center of the substrate; and controlling polishing pressure applied from the polishing head to the substrate based on the signal values generated by the first film-thickness sensor and the second film-thickness sensor.

Polishing systems and methods for polishing a substrate are provided. The method includes polishing a substrate using a polishing pad and monitoring a thickness of the polishing pad. The monitoring of the thickness of the polishing pad is performed by detecting an eddy current generated from a conductor element below a bottom surface of the polishing pad. The method also includes replacing the polishing pad with a second polishing pad if the thickness of the polishing pad is smaller than a predetermined value.

A polishing method which can acquire an actual position of a film-thickness measurement point, and can therefore apply an optimum polishing pressure to a substrate such as a wafer is disclosed. The method includes: causing a substrate detection sensor to generate substrate detection signals in a preset cycle and causing a film-thickness sensor to generate a film-thickness signal at a predetermined measurement point during polishing of the substrate while the substrate detection sensor and the film-thickness sensor are moving across the surface of the substrate; calculating an angle of eccentricity of a center of the substrate relative to a center of the polishing head from the number of substrate detection signals; correcting a position of the predetermined measurement point based on the angle of eccentricity; and controlling polishing pressure at which the polishing head presses the substrate based on the film-thickness signal and the corrected position of the predetermined measurement point.

A method of controlling polishing includes sweeping a sensor of an in-situ monitoring system across a substrate as a layer of the substrate undergoes polishing, generating from the in-situ monitoring system a sequence of signal values that depend on a thickness of the layer, detecting from the sequence of signal values, a time that the sensor traverses a leading edge of the substrate or a retaining ring and a time that the sensor traverses a trailing edge of the substrate or retaining ring; and for each signal value of at least some of the sequence of signal values, determining a position on the substrate for the signal value based on the time that the sensor traverses the leading edge and the time that the sensor traverses a trailing edge.

The present disclosure provides a method of detecting and preventing grind burn from developing on a gear. The method includes performing acoustic emission testing while the gear is being ground during a grinding operation. The grinding wheel is evaluated during an eddy current test to detect material buildup on the grinding wheel which could cause grind burn. In addition, the method includes collecting swarf from the gear during the grinding operation and inspecting the swarf for an indication of grind burn.