Kla Tencor Corporation

Kla Corporation

Oliver Ache

Frank Laske

Stefan Eyring

Nadav Gutman

Carey Phelps

An overlay target includes a grating-over-grating structure with a bottom grating structure disposed on a specimen and a top grating structure disposed on the bottom grating structure. The overlay target further includes a calibration scan location including the bottom grating structure but not the top grating structure and an overlay scan location including the top grating structure and the bottom grating structure.

Target and algorithm to measure overlay by modeling back scattering electrons on overlapping structures

A method with increased throughput for measuring positions of structures on a substrate is disclosed. The substrate is taken from a load port of a metrology machine and is placed immediately in a stage of the metrology machine. At least two measurement loops are carried out, wherein a first measurement loop is started at a time when a substrate temperature is different from the temperature at the stage, and at least one second measurement loop is started at a time after the first measurement loop when the substrate temperature is different from the temperature at the stage. A model is used to calculate from the measured data, taken while there is a temperature mismatch between the stage and the substrate, a real grid of positions of structures on the substrate, corresponding to a situation where the temperature of the stage matches the temperature of the substrate.

Method for measuring positions of structures on a substrate and computer program product for determining positions of structures on a substrate

A method for correcting optical errors occurring in coordinates of positions of a plurality of targets measured via an imaging system comprising a field of view. The plurality of targets includes a first array of targets and a second array of targets overlapping the first array of targets, and a portion of the plurality of targets are outside of the field of view. The method broadly includes the following steps: a) placing the first array of targets in the field of view of the imaging system; b) measuring coordinates of each target within the first array of targets repeatedly via the imaging system; c) placing the second array of targets in the field of view of the imaging system; d) measuring coordinates of each target within the second array of targets repeatedly via the imaging system; e) determining an alignment function from the measurement results of step b, step d, or steps b and d, the alignment function being a function of coordinates of the field of view of the imaging system and giving an additive correction for optical errors of the coordinates of positions of the plurality of targets measured by the imaging system; f) correcting the coordinates of the positions of the plurality of targets measured by the imaging system by adding the respective value of the alignment function at the field-of-view coordinates at which the coordinates of the position of the respective target were measured; and, g) obtaining a final result for the position of each target of the plurality of targets by averaging over the corrected coordinates found in step f for the respective target at each relative position of the plurality of targets and field of view of the imaging system.

Method for correcting position measurements for optical errors and method for determining mask writer errors

A method is disclosed for correcting errors introduced by optical distortions or aberrations in the measured values of coordinates of targets of an array of targets, like for example structures on a wafer or a photolithography mask. The array of targets is placed into a field of view of an imaging system via which the coordinates are to be measured. The array of targets is placed at different relative positions with respect to the field of view, and for each relative position the coordinates of the targets relative to the array of targets are determined by measurements. From the results of these measurements an alignment function, giving a correction for optical errors as a function of the position in the field of view, is derived. The measured coordinates are corrected by the alignment function. The corrected coordinates can be used to identify registration errors of a mask writer.

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Leun, Germany

Oliver Ache