Invention Grant
- Patent Title: Methods and patterning devices and apparatuses for measuring focus performance of a lithographic apparatus, device manufacturing method
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Application No.: US15384084Application Date: 2016-12-19
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Publication No.: US10474039B2Publication Date: 2019-11-12
- Inventor: Paul Christiaan Hinnen , Simon Gijsbert Josephus Mathijssen , Maikel Robert Goosen , Maurits Van Der Schaar , Arie Jeffrey Den Boef
- Applicant: ASML Netherlands B.V.
- Applicant Address: NL Veldhoven
- Assignee: ASML Netherlands B.V.
- Current Assignee: ASML Netherlands B.V.
- Current Assignee Address: NL Veldhoven
- Agency: Sterne, Kessler, Goldstein & Fox P.L.L.C.
- Priority: EP15201611 20151221
- Main IPC: G03B27/34
- IPC: G03B27/34 ; G03F7/20

Abstract:
A lithographic apparatus (LA) prints product features and at least one focus metrology pattern (T) on a substrate. The focus metrology pattern is defined by a reflective reticle and printing is performed using EUV radiation (404) incident at an oblique angle (θ). The focus metrology pattern comprises a periodic array of groups of first features (422). A spacing (S1) between adjacent groups of first features is much greater than a dimension (CD) of the first features within each group. Due to the oblique illumination, the printed first features become distorted and/or displaced as a function of focus error. Second features 424 may be provided as a reference against which displacement of the first features may be seen. Measurement of this distortion and/or displacement may be by measuring asymmetry as a property of the printed pattern. Measurement can be done at longer wavelengths, for example in the range 350-800 nm.
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