Kla-Tencor Technologies Corporation

Paola Dececco

John Fielden

Michael E Adel

Ady Levy

Mark Ghinovker

Christopher F Bevis

Noah Bareket

Walter Dean Mieher

Ian R Smith

Michael Friedmann

Dan Wack

Thaddeus Gerard Dziura

Anatoly Fabrikant

Kenneth P Gross

Piotr S Zalicki

Boris Golovanevsky

Boris Golovanesky

Ken Gross

Disclosed are techniques, apparatus, and targets for determining overlay error between two layers of a sample. A plurality of targets is provided. Each target includes a portion of the first and second structures and each is designed to have an offset between its first and second structure portions. The targets are illuminated with electromagnetic radiation to thereby obtain spectra from each target at a &#x2212;1diffraction order and a +1diffraction order. It is determined whether there are any overlay error between the first structures and the second structures using a scatterometry technique based on the detected spectra by (i) for each target, determining a first differential intensity between the &#x2212;1diffraction order and a +1diffraction order, (ii) for a plurality of pairs of targets each having a first target and a second target, determining a second differential intensity between the first differential intensity of the first target and the first differential intensity of the second target, and (iii) determining any overlay error between the first structures and the second structures using a scatterometry technique based on the second differential intensities determined from each target pair.

Apparatus and methods for detecting overlay errors using scatterometry

Disclosed are techniques, apparatus, and targets for determining overlay error between two layers of a sample. Target A is designed to have an offset Xa between its first and second structures portions; target B is designed to have an offset Xb; target C is designed to have an offset Xc; and target D is designed to have an offset Xd. Each of the offsets Xa, Xb, Xc and Xd is preferably different from zero; Xa is an opposite sign and differ from Xb; and Xc is an opposite sign and differs from Xd. The targets A, B, C and D are illuminated with electromagnetic radiation to obtain spectra S, S, S, and Sfrom targets A, B, C, and D, respectively. Any overlay error between the first structures and the second structures is then determined using a linear approximation based on the obtained spectra S, S, S, and S.

Disclosed is a method of determining an overlay error between two layers of a multiple layer sample. For a plurality of periodic targets that each have a first structure formed from a first layer and a second structure formed from a second layer of the sample, an optical system is employed to thereby measure an optical signal from each of the periodic targets. There are predefined offsets between the first and second structures. An overlay error is determined between the first and second structures by analyzing the measured optical signals from the periodic targets using a scatterometry overlay technique based on the predefined offsets.

Disclosed are techniques, apparatus, and targets for determining overlay error between two layers of a sample. In one embodiment, a method for determining overlay between a plurality of first structures in a first layer of a sample and a plurality of second structures in a second layer of the sample is disclosed. Targets A, B, C and D that each include a portion of the first and second structures are provided. Target A is designed to have an offset Xa between its first and second structures portions; target B is designed to have an offset Xb between its first and second structures portions; target C is designed to have an offset Xc between its first and second structures portions; and target D is designed to have an offset Xd between its first and second structures portions. Each of the offsets Xa, Xb, Xc and Xd is preferably different from zero; Xa is an opposite sign and differ from Xb; and Xc is an opposite sign and differs from Xd. The targets A, B, C and D are illuminated with electromagnetic radiation to obtain spectra S, S, S, and Sfrom targets A, B, C, and D, respectively. Any overlay error between the first structures and the second structures is then determined using a linear approximation based on the obtained spectra S, S, S, and S.

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Redwood City, CA, United States of America

Paola Dececco