Abstract: A process for determining critical dimension bias or overlay error in a substrate formed by a lithographic process initially provides an array of elements on a substrate, the array comprising a plurality of spaced, substantially parallel elements having a length and a width. The sum of the width of an element and the spacing of adjacent elements define a pitch of the elements. Edges of the elements are aligned along a line forming opposite array edges, with the distance between array edges comprising the array width. An optical metrology tool used for measurement of the array is adjustable for one or more of i) wavelength of the light source, ii) numerical aperture value or iii) partial coherence.

Abstract: A method of measuring bias of a minimum feature in a lithographic process uses creating an array of elements having a width and space corresponding to the minimum feature, and a length. The length change of the array element resulting from image shortening effect from a lithographic process is measured and the bias of the element in the width dimension is calculated. A test site having groups of array elements is described which facilitate automatic bias measurement of array lengths and separations and especially allows the use of non SEM metrology tools which is otherwise incapable of measuring the minimum feature width being monitored. Measurements by this method and test site used to control lithographic processing of substrates in manufacturing, routine monitoring of product substrates and lithographic tool and process for minimum bias, are disclosed.

Abstract: An automated system utilizes self-labeled targets to locate and identify specific targets. Lithographic targets used for alignment, measurement and/or testing of features on a semiconductor substrate are assigned a unique pitch to identify the target. The targets have a plurality of elements with at least three edges distinguishable by an optical metrology tool. An invariant and unique process characteristic is defined by distances between elements or three or more edges, which is the pitch of the target. An optical metrology tool having a microprocessor and memory resolves the target elements, measures the distance between elements or edges, calculates the target pitch, compares it to the target pitch in memory, and determines whether the actual target pitch equals the stored target pitch to identify the target on the substrate.