Novel diffraction-based overlay metrology utilizing phase-based overlay for improved robustness

Masazumi Matsunobu; Toshiharu Nishiyama; Michio Inoue; Richard Housley; Cornel Bozdog; Justin Lim; Brian Watson; Jason Reece; Steve McCandless; Olger Zwier; Maurits van der Schaar; Murat Bozkurt; Masudur al Arif; Elliott McNamara; Pieter Kapel; Alan Khan; Simon Strom; Paul Turner; Ping Olson; Ewoud van West

doi:10.1117/12.2584759

22 February 2021 Novel diffraction-based overlay metrology utilizing phase-based overlay for improved robustness

Masazumi Matsunobu, Toshiharu Nishiyama, Michio Inoue, Richard Housley, Cornel Bozdog, Justin Lim, Brian Watson, Jason Reece, Steve McCandless, Olger Zwier, Maurits van der Schaar, Murat Bozkurt, Masudur al Arif, Elliott McNamara, Pieter Kapel, Alan Khan, Simon Strom, Paul Turner, Ping Olson, Ewoud van West

Author Affiliations +

Proceedings Volume 11611, Metrology, Inspection, and Process Control for Semiconductor Manufacturing XXXV; 1161126 (2021) https://doi.org/10.1117/12.2584759
Event: SPIE Advanced Lithography, 2021, Online Only

Abstract

The current state of the art ADI overlay metrology relies on multi-wavelength uDBO techniques. Combining the wavelengths results in better robustness against process effects like process induced grating asymmetries. Overlay information is extracted in the image plane by determining the intensity asymmetry in the 1st order diffraction signals of two grating pairs with an intentional shift (bias). In this paper we discuss a next evolution in DBO targets where a target is created with multiple biases. These so called cDBO (continuous bias DBO) targets have a slightly different pitch between top and bottom grating, which has the effect of having a different bias values along the grating length and are complimentary to the uDBO technology. Where for the uDBO target, the diffraction results in a uniform Intensity pattern that carries the Overlay signal, for cDBO, an oscillating intensity pattern occurs, and the Overlay information is now captured in the phase of that pattern. Phase-based Overlay has an improved, intrinsic robustness over intensity-based overlay and can reduce the need for multi-wavelength techniques in several cases. Results on memory technology wafers confirm that the swing-curve (through-wavelength) behavior is indeed more stable for phase-based DBO target and that for accurate Overlay, this target can be qualified with a single wavelength recipe (compared to the uDBO dual wavelength recipe). In this paper, both initial results on a Micron feasibility wafer will be shown as well as demonstrated capability in a production environment.

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Masazumi Matsunobu, Toshiharu Nishiyama, Michio Inoue, Richard Housley, Cornel Bozdog, Justin Lim, Brian Watson, Jason Reece, Steve McCandless, Olger Zwier, Maurits van der Schaar, Murat Bozkurt, Masudur al Arif, Elliott McNamara, Pieter Kapel, Alan Khan, Simon Strom, Paul Turner, Ping Olson, and Ewoud van West "Novel diffraction-based overlay metrology utilizing phase-based overlay for improved robustness", Proc. SPIE 11611, Metrology, Inspection, and Process Control for Semiconductor Manufacturing XXXV, 1161126 (22 February 2021); https://doi.org/10.1117/12.2584759

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