Model-based single parameter measurement

A method comprising:

• illuminating a metrology target fabricated on a semiconductor wafer under measurement with an amount of illumination radiation generated by an illumination source;
• generating an amount of raw measurement signals from radiation collected from the semiconductor wafer in response to the amount of illumination radiation illuminating the metrology target fabricated on the semiconductor wafer;
• determining a reduced set of raw measurement signals by applying a trained parameter isolation model to the amount of raw measurement signals, wherein the trained parameter isolation model is trained based on measurements of a first set of instances of the metrology target having known values of a plurality of incidental model parameters and known values of a parameter of interest and a second set of instances of the metrology target having nominal values of the plurality of incidental parameters and the known values of the parameter of interest;
• estimating a value of a parameter of interest of the metrology target based on the reduced set of raw measurement signals and a measurement model, wherein the plurality of incidental model parameters of the measurement model are fixed to the nominal values;
• and
• communicating an indication of the values of the parameter of interest to a semiconductor fabrication tool that causes the semiconductor fabrication tool to adjust one or more parameters of a fabrication process performed by the semiconductor fabrication tool to achieve a desired output from the semiconductor fabrication tool.

A method comprising:

• receiving an amount of reference measurement signals associated with measurements of a first set of instances of a metrology target having known values of a plurality of incidental model parameters and known values of a parameter of interest, wherein the measurements of the first set of instances of the metrology target are simulated by a measurement model;
• receiving an amount of reduced reference measurement signals associated with measurements of a second set of instances of the metrology target having nominal values of the plurality of incidental model parameters and the known values of the parameter of interest, wherein the measurements of the second set of instances of the metrology target are simulated by the measurement model;
• training a parameter isolation model, wherein the training of the parameter isolation model is based on mapping the reference measurement signals to the reduced reference measurement signals;
• illuminating a third instance of the metrology target fabricated on a semiconductor wafer under measurement with an amount of illumination radiation generated by an illumination source;
• generating an amount of raw measurement signals from radiation collected from the semiconductor wafer in response to the amount of illumination radiation illuminating the third instance of the metrology target fabricated on the semiconductor wafer;
• determining a reduced set of raw measurement signals by applying the trained parameter isolation model to the amount of raw measurement signals;
• estimating a value of a parameter of interest of the third instance of the metrology target based on the reduced set of raw measurement signals and a measurement model, wherein the plurality of incidental model parameters of the measurement model are fixed to the nominal values;
• and
• communicating an indication of the values of the parameter of interest to a semiconductor fabrication tool that causes the semiconductor fabrication tool to adjust one or more parameters of a fabrication process performed by the semiconductor fabrication tool to achieve a desired output from the semiconductor fabrication tool.