Patent ID: 7487053

Claim:
A method of refining a virtual profile library, the method comprising: obtaining a reference signal measured off a reference structure on a semiconductor wafer with a metrology device; selecting a best match of the reference signal in a virtual profile data space, the virtual profile data space having data points with specified accuracy values, the data points representing virtual profile parameters and associated virtual profile signals, the virtual profile parameters characterizing the profile of an integrated circuit structure, the best match being a data point of the profile data space with a signal closest to the reference signal; determining refined virtual profile parameters corresponding to the reference signal based on the virtual profile parameters of the selected virtual profile signal using a refinement procedure; determining a reference profile shape associated with reference signal; selecting a best match profile of the reference profile shape in the virtual profile data space, the data points representing virtual profile shapes, virtual profile parameters and associated virtual profile signals, virtual profile data characterizing the virtual profile shape of an integrated circuit structure, the best match profile being a data point of the virtual profile data space with a virtual profile shape closest to the reference profile shape; selecting a first virtual profile shape within a subset of the virtual profile data space, the virtual profile data space subset containing the reference profile shape and data points proximate to the data point associated with the best match profile; simulating a signal off a structure with virtual profile parameters corresponding to the selected first virtual profile; calculating a difference between the reference signal and the simulated signal; comparing the difference to a virtual profile library creation criteria; and either storing the first virtual profile shape and the virtual profile data associated with the first virtual profile shape if the virtual profile library creation criteria is met, or applying a corrective action if the virtual profile library creation criteria is not met.