Compensation for substrate doping in edge reconstruction for in-situ electromagnetic inductive monitoring

A computer program product, tangibly embodied in a non-transitory computer readable medium, comprising instructions to cause one or more computers to:

• store or generate a modified reference trace representing a sequence of measurements taken by a sensor, of an in-situ electromagnetic induction monitoring system, moving across a bare, n-type or p-type doped reference semiconductor wafer as modified by a neural network, wherein the neural network is configured to compensate for distortions caused by a partial overlap between an edge of a semiconductor wafer and a magnetic field generated by the in-situ electromagnetic induction monitoring system, wherein the neural network comprises an input layer, an output layer, and one or more hidden layers;
• receive from the in-situ electromagnetic induction monitoring system, as a conductive layer disposed over the semiconductor wafer of a substrate is polished, a measured trace including measured signal values at multiple different locations on the semiconductor wafer, wherein the measured signal values depend on a thickness of the conductive layer, wherein the measured trace is a sequence of measurements as the sensor moves across the substrate;
• process at least a portion of the measured trace including the measured signal values at multiple different locations on the semiconductor wafer as input through the neural network configured to compensate for the distortions caused by the partial overlap between the edge of the semiconductor wafer and the magnetic field generated by the in-situ electromagnetic induction monitoring system to generate a modified measured trace;
• generate an adjusted trace to at least partially compensate for a contribution of conductivity of the semiconductor wafer to the measured trace, wherein the instructions to generate the adjusting trace include subtracting the modified reference trace from the modified measured trace;
• and
• at least one of halt polishing or modify a polishing parameter based on the adjusted trace.

A polishing system, comprising:

• a support to hold a polishing pad;
• a carrier head to hold a substrate in contact with the polishing pad;
• an in-situ electromagnetic induction monitoring system to monitor the substrate as a conductive layer on the substrate is polished to generate a measured trace including measured signal values at multiple different locations on a semiconductor wafer, wherein the measured signal values depend on a thickness of the conductive layer;
• and
• a controller configured to
• store or generate a modified reference trace representing a sequence of measurements taken by a sensor, of the in-situ electromagnetic induction monitoring system, moving across a bare, n-type or p-type doped reference semiconductor wafer as modified by a neural network, wherein the neural network is configured to compensate for distortions caused by a partial overlap between an edge of the semiconductor wafer and a magnetic field generated by the in-situ electromagnetic induction monitoring system, wherein the neural network comprises an input layer, an output layer, and one or more hidden layers,
• receive the measured trace from the in-situ electromagnetic induction monitoring system, wherein the measured trace is a sequence of measurements as the sensor moves across the substrate,
• process at least a portion of the measured trace including the measured signal values at multiple different locations on the semiconductor wafer as input through the neural network configured to compensate for the distortions caused by the partial overlap between the edge of the semiconductor wafer and the magnetic field generated by the in-situ electromagnetic induction monitoring system to generate a modified measured trace,
• generate an adjusted trace to at least partially compensate for a contribution of conductivity of the semiconductor wafer to the measured trace, including subtracting the modified reference trace from the modified measured trace, and
• at least one of halt polishing or modify a polishing parameter based on the adjusted trace.