Patent ID: 8173450
Filing Date: 2012-05-08
Classification: H01J,H01L

Abstract:
1. A method for designing an etch stage measurement system involving an etch process for one or more layers on a substrate, the etch stage measurement system comprising metrology devices and a metrology processor, the etch stage measurement system configured to meet two or more etch stage measurement objectives, the etch process performed in an etch process tool, the etch process tool having an etch chamber, a controller, and one or more etch process parameters, the method comprising: (a) setting the two or more etch stage measurement objectives; (b) selecting two or more optical metrology devices for measuring electromagnetic energy off the chamber or off the substrate during the etch process; (c) obtaining etch stage measurements using the selected two or more optical metrology devices; (d) obtaining an actual etch stage data for each of the etch stage measurements using one or more reference measurement technologies; (e) developing a correlation algorithm of the etch stage measurements to the actual etch stage data; (f) extracting an etch measurement value using the developed correlation algorithm and an etch stage measurement using the selected two or more optical metrology devices; (g) comparing calculated etch stage measurement objectives using the extracted etch measurement value to the set two or more etch stage measurement objectives; and (h) if the set two or more etch stage measurement objectives are not met, modifying the selected two or more optical metrology devices, refining the correlation algorithm, and/or enhancing the etch stage measurement by adjusting for noise in the measured electromagnetic energy and iterating steps (c) to (h) 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.