Patent Document ID: 7627622
Application ID: 10904531
Patent Status: 1

Claim One:
1. A program storage device readable by a machine, tangibly embodying a program of instructions executable by a machine to perform a method of fitting a curve to a plurality of data points comprising: a) receiving a plurality of data points, wherein said plurality of data points are representative of image size measurements of structures formed on a substrate at different settings of a photolithographic tool; b) fitting a first curve to a first set of data points selected from said plurality of data points; c) including other data points from said plurality of data points that are not included in said first set of data points individually with said first set of data points in an iterative manner until an ending criteria is met to form another set of data points in response to another curve fit to said another set of data points upon each iteration that satisfies a first pre-determined condition; d) accepting a curve fitted immediately prior to said ending criteria being met as a best fit curve for said plurality of data points; e) determining a best focus condition from said best fit curve, wherein said best focus condition comprises a focus value which satisfies a third pre-determined condition; and f) outputting said determined focus value to said photolithographic tool, wherein a focus setting of said photolithographic tool is adjusted to said determined focus value.