Patent ID: 7571074
Filing Date: 2009-08-04
Classification: G01B,G03F

Abstract:
1. A method of using a thickness-dependent profile library to facilitate optical measurements, the method comprising: receiving a wafer, wafer data, and one or more input messages, wherein the wafer comprises a plurality of dies and a number of measurement sites, the wafer data comprises wafer state data, and at least one of the one or more input messages comprises feed-forwarded tuning data; determining a wafer state for the wafer, wherein a thickness-dependent profile library is identified using the wafer state, and comprises data for wavelengths between approximately 100 nm and approximately 1000 nm; determining a real-time wafer thickness using the feed-forwarded tuning data; establishing a first wafer-thickness-dependent profile data space in the thickness-dependent profile library using the real-time wafer thickness, the first wafer-thickness-dependent profile data space comprising wafer-thickness-dependent profile signal data and associated wafer-thickness-dependent profile structure data based on real-time wafer thickness, and comprising data points having accuracy limits based on real-time wafer thickness data; selecting a measurement site using the real-time wafer thickness, wherein the measurement site includes a reference structure; establishing an updated measurement recipe using the real-time wafer thickness; measuring a signal off the reference structure using the updated measurement recipe, the measurement generating an updated measurement signal that is dependent upon the real-time wafer thickness; selecting a best estimate signal for the updated measurement signal, the best estimate signal being a data point of the first wafer-thickness-dependent profile data space with a thickness-dependent profile signal substantially close to the updated measurement signal, the best estimate signal having a best estimate profile structure and/or best estimate profile parameters associated therewith; calculating a difference between the updated measurement signal and the best estimate signal; comparing the difference to a matching criteria; and either identifying the reference structure as a member of the thickness-dependent profile library and identifying the wafer as an updated wafer if matching criteria is met, or applying a first corrective action if the matching criteria are not met.