Patent ID: 8173451

Claim:
A system for measuring etch stage of an etch process of one or more layers on a substrate, the etch stage measurement configured to meet two or more etch stage measurement objectives, the system comprising: an etch process tool configured to etch the one or more layers on the substrate, the etch process tool having an etch chamber, a controller, and one or more etch process parameters; a first optical metrology device coupled to the etch process tool, the first optical metrology device configured to measure electromagnetic energy from the etch chamber; a second optical metrology device coupled to the etch process tool, the second optical metrology device configured to illuminate the substrate in one or more sites and measure the diffraction signals from the one or more sites; and a processor coupled to the etch process tool, the first optical metrology device, and the second optical metrology device, the processor configured to develop a correlation algorithm of the etch stage measurements to actual etch stage data, extract an etch measurement value using etch stage measurements from the first and second optical metrology devices and the correlation of measured electromagnetic energy from the first and second optical metrology devices to actual etch stage data, if calculated two or more etch stage measurement objectives compared to a set two or more etch stage measurement objectives are not met, modify first and second optical metrology devices, refine the correlation algorithm, and/or enhance the etch stage measurement by adjusting for noise in the measured electromagnetic energy, and iterate developing the correlation algorithm, extracting the etch measurement value, comparing the calculated two or more etch stage measurement objectives to the set two or more etch stage measurement, and modifying the first and/or the second optical metrology devices, refining the correlation algorithm, and/or enhancing the etch stage measurement by adjusting for noise in the measured electromagnetic energy objectives until the two or more etch stage measurement objectives are met, wherein refining the correlation algorithm comprises using non-linear functional relationships between the electromagnetic energy measurements and the actual etch stage measurement data, wherein the non-linear functional relationships include arbitrary functions, composite functions, and least squares fit solutions wherein least squares fit can include nonlinear fitting methods, searching parameter space methods, grid search methods, gradient search methods, expansion methods, and Marquardt methods.