Parametric optimization of optical metrology model

A method of determining the profile of an integrated circuit structure from a measured metrology signal, the method comprising:

• a) developing an optical metrology model for a structure, the metrology model including a profile model of the structure, the profile model comprising profile parameters;
• b) selecting a first profile parameter for determination of value;
• c) determining the value of the selected first profile parameter;
• d) determining values of remaining profile parameters using the determined value of the selected first profile parameter and using one or more measured metrology signals off the structure;
• e) setting one or more subsequent termination criteria for terminating parameter predetermination;
• f) selecting a subsequent profile parameter for determination of value;
• g) determining the value of the selected subsequent profile parameter;
• h) determining values of remaining profile parameters using the determined values of the selected first and selected subsequent profile parameters and using one or more measured metrology signals off the structure;
• and
• i) iterating steps f) to h) until the one or more subsequent termination criteria for parameter predetermination are met.

A method of determining the profile of an integrated circuit structure from a measured metrology signal, the method comprising:

• developing an optical metrology model for a structure, the metrology model including a profile model of the structure, the profile model comprising profile parameters;
• selecting a plurality of profile parameters for determination of value;
• determining values of the selected plurality of profile parameters;
• and
• determining values of remaining profile parameters using the determined values of the selected plurality of profile parameters and using one or more measured metrology signals off the structure.

A method of determining the profile of an integrated circuit structure from a measured metrology signal, the method comprising:

• a) setting one or more termination criteria for parametric optimization;
• b) developing an optical metrology model for a structure, the metrology model including a profile model of the structure, the profile model comprising profile parameters;
• c) selecting a plurality of profile parameters for determination of value;
• d) determining values of the selected plurality of profile parameters;
• e) ranking the plurality of profile parameters using the one or more termination criteria for parametric optimization;
• f) determining values of remaining profile parameters using the determined values of one or more profile parameters of the selected plurality of profile parameters and using at least one measured metrology signal off the structure;
• and
• g) iterating steps c), d), e), and f) until the one or more termination criteria for parametric optimization are met.

A system for determining the profile of an integrated circuit structure, comprising:

• a parametric processor configured to obtain a measured metrology signal and a first simulated metrology signal, the first simulated metrology signal having an associated profile model of the structure, wherein the associated profile model is defined by a set of profile parameters;
• and
• a profile evaluator coupled to the parametric processor, wherein when the measured metrology signal and the first simulated metrology signal match within a first termination criterion, the profile evaluator is configured to:
• a) select at least one profile parameter from the set of profile parameters of the profile model associated with the first simulated metrology signal;
• b) determine a value for the selected profile parameter;
• c) obtain a second simulated metrology signal having an associated profile model of the structure defined by a set of profile parameters with at least one profile parameter equal or close to the determined value for the selected profile parameter;
• and
• d) when the measured metrology signal and the second simulated metrology signal match within a second termination criterion, determine values for one or more remaining profile parameters from the set of profile parameters of the profile model associated with the second simulated metrology signal.

A computer-readable storage medium containing computer executable code to determine the profile of a wafer structure from a measured metrology signal by instructing a computer to operate as follows:

• a) obtaining an optical metrology model for a structure, the metrology model including a profile model of the structure, the profile model comprising profile parameters;
• b) selecting a first profile parameter for determination of value;
• c) determining the value of the selected first profile parameter;
• d) determining values of remaining profile parameters using the determined value of the selected first profile parameter and using one or more measured metrology signals off the structure;
• e) setting one or more subsequent termination criteria for terminating parameter predetermination;
• f) selecting a subsequent profile parameter for determination of value;
• g) determining the value of the selected subsequent profile parameter;
• h) determining values of remaining profile parameters using the determined values of the selected first and selected subsequent profile parameters and using one or more measured metrology signals off the structure;
• and
• i) iterating steps f) to h) until the one or more subsequent termination criteria for parameter predetermination are met.

A computer-readable storage medium containing computer executable code to determine the profile of a wafer structure from a measured metrology signal by instructing a computer to operate as follows:

• a) setting one or more termination criteria for parametric optimization;
• b) obtaining an optical metrology model for a structure, the metrology model including a profile model of the structure, the profile model comprising profile parameters;
• c) selecting a plurality of profile parameters for determination of value;
• d) determining values of the selected plurality of profile parameters;
• e) ranking the plurality of profile parameters using the one or more termination criteria for parametric optimization;
• f) determining values of remaining profile parameters using the determined values of one or more profile parameters of the selected plurality of profile parameters and using at least one measured metrology signal off the structure;
• and
• g) iterating steps c), d), e), and f) until the one or more termination criteria for parametric optimization are met.