Optical metrology model optimization for process control

A method of evaluating the adequacy of a profile model of a wafer structure to be used for process control of a fabrication process to fabricate the wafer structure, the profile model including profile model parameters, the method comprising:

• a) selecting one or more types of process control to be used in controlling the fabrication process;
• b) selecting one or more profile model parameters to be measured in implementing the one or more selected types of process control;
• c) setting an acceptable range for each of the selected one or more profile model parameters;
• d) setting one or more statistical metric criteria that define an acceptable amount of variation in measurements obtained using a scatterometer and a critical dimension scanning electron microscope (CDSEM);
• e) selecting a profile model to be used with the scatterometer;
• f) obtaining a measurement of the one or more profile model parameters using the scatterometer and the selected profile model;
• g) obtaining a measurement of the one or more profile model parameters using the CDSEM;
• h) calculating the one or more statistical metric criteria based on the measurements of the one or more profile model parameters obtained using the scatterometer and the CDSEM;
• i) comparing the one or more calculated statistical metric criteria to the one or more set statistical metric criteria to evaluate the adequacy of the selected profile model.

A system for evaluating the adequacy of a profile model of a wafer structure to be used for process control of a fabrication process to fabricate the wafer structure, the profile model including profile model parameters, the system comprising:

• a wafer having a structure formed thereon, the structure characterized by a profile model, the profile model having profile model parameters;
• a first semiconductor fabrication device configured to perform a first fabrication process on the wafer;
• a second semiconductor fabrication device configured to perform one or more subsequent fabrication processes on the wafer;
• a first metrology tool configured to measure the structure;
• a second metrology tool configured to calibrate the first metrology tool;
• and
• a processor configured to:
• a) select one or more types of process control to be used in controlling the fabrication process;
• b) select one or more profile model parameters to be measured in implementing the one or more selected types of process control;
• c) set an acceptable range for each of the selected one or more profile model parameters;
• d) select a first metrology tool to be used in measuring the one or more selected profile model parameters of the structure during the fabrication process;
• e) select a second metrology tool to be used to calibrate the first metrology tool;
• f) set one or more statistical metric criteria that define an acceptable amount of variation in measurements obtained using the first metrology tool and the second metrology tool;
• g) select a profile model to be used with the first metrology tool;
• h) obtain a measurement of the one or more profile model parameters using the first metrology tool and the selected profile model;
• i) obtain a measurement of the one or more profile model parameters using the second metrology tool;
• j) calculate the one or more statistical metric criteria based on the measurements of the one or more profile model parameters obtained using the first and second metrology tools;
• k) compare the one or more calculated statistical metric criteria to the one or more set statistical metric criteria to evaluate the adequacy of the selected profile model.

A computer-readable storage medium containing computer executable instructions for causing a computer to optimize a metrology profile model of a wafer structure for fabrication process control, comprising instructions for:

• a) selecting one or more types of process control to be used in controlling the fabrication process;
• b) selecting one or more profile model parameters to be measured in implementing the one or more selected types of process control;
• c) setting an acceptable range for each of the selected one or more profile model parameters;
• d) selecting a first metrology tool to be used in measuring the one or more selected profile model parameters of the wafer structure during the fabrication process;
• e) selecting a second metrology tool to be used to calibrate the first metrology tool;
• f) setting one or more statistical metric criteria that define an acceptable amount of variation in measurements obtained using the first metrology tool and the second metrology tool;
• g) selecting a profile model to be used with the first metrology tool;
• h) obtaining a measurement of the one or more profile model parameters using the first metrology tool and the selected profile model;
• i) obtaining a measurement of the one or more profile model parameters using the second metrology tool;
• j) calculating the one or more statistical metric criteria based on the measurements of the one or more profile model parameters obtained using the first and second metrology tools;
• and
• k) comparing the one or more calculated statistical metric criteria to the one or more set statistical metric criteria to evaluate the adequacy of the selected profile model.