Inspection Apparatus and Methods, Substrates Having Metrology Targets, Lithographic System and Device Manufacturing Method

Patent metadata

Field	Value
Publication number	US-2018239263-A1
Application number	US-201815961377-A
Country	US
Kind code	A1
Filing date	Apr 24, 2018
Priority date	Oct 30, 2013
Publication date	Aug 23, 2018
Grant date	—

Abstract

Disclosed is an inspection apparatus for use in lithography. It comprises a support for a substrate carrying a plurality of metrology targets; an optical system for illuminating the targets under predetermined illumination conditions and for detecting predetermined portions of radiation diffracted by the targets under the illumination conditions; a processor arranged to calculate from said detected portions of diffracted radiation a measurement of asymmetry for a specific target; and a controller for causing the optical system and processor to measure asymmetry in at least two of said targets which have different known components of positional offset between structures and smaller sub-structures within a layer on the substrate and calculate from the results of said asymmetry measurements a measurement of a performance parameter of the lithographic process for structures of said smaller size. Also disclosed are substrates provided with a plurality of novel metrology targets formed by a lithographic process.

First claim

1 . A substrate provided with metrology targets formed by a lithographic process, each of the metrology targets comprising:
structures arranged to repeat with a spatial period in at least a first direction, wherein the metrology targets include targets each of which comprises sub-structures of a size several times smaller than the spatial period, wherein each of the targets is formed with a positional offset between two interleaved populations of sub-structures that is a combination of both known and unknown components, the known components being different for different targets.

2 . The substrate of claim 1 , wherein two or more of the targets having different known offsets between the interleaved populations of sub-structures are formed in close proximity with one another so as to form a composite target, while other such composite targets are distributed across the substrate.

3 . The substrate of claim 1 , wherein the lithographic process used to form the metrology targets comprises a double patterning process.

4 . A pair of patterning devices for use in a lithographic process, the patterning devices defining patterns which when applied sequentially to a substrate will produce a substrate provided with metrology targets formed by a lithographic process, each of the metrology targets comprising:
structures arranged to repeat with a spatial period in at least a first direction, wherein the metrology targets include targets each of which comprises sub-structures of a size several times smaller than the spatial period, wherein each of the targets is formed with a positional offset between two interleaved populations of sub-structures that is a combination of both known and unknown components, the known components being different for different ones of the targets.

5 . The pair of patterning devices of claim 4 , wherein two or more of the targets having different known offsets between the interleaved populations of sub-structures are formed in close proximity with one another so as to form a composite target, while other such composite targets are distributed across the substrate.

6 . The pair of patterning devices claim 4 , wherein the lithographic process used to form the metrology targets comprises a double patterning process.

7 . A method comprising:
measuring −1 st order scatterometry image of double patterned gratings on a substrate with offsets between populations a using a first illumination mode; measuring +1 st order scatterometry image of the double patterned gratings using a second illumination mode; determining a region of interest in each of the double patterned gratings from the +/1 1 st order images; calculation a difference image of each of the double patterned gratings from the +/1 1 st order images to determine asymmetry; determining overlay between the populations based on the asymmetry; and correcting for at-resolution offsets based on the asymmetry.

Assignees

• Asml Netherlands Bv

Inventors

• Mathijssen Simon Gijsbert Josephus
• Hunsche Stefan
• Maria Van Kraaij Markus Gerardus Martinus

Classifications

• G03F7/213 Primary

  Exposing with the same light pattern different positions of the same surface at the same time {(G03F7/70 takes precedence)} · CPC title

• G03F7/70616

  Monitoring the printed patterns · CPC title

• G03F7/70633 Primary

  Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching · CPC title

• G03F7/70683 Primary

  Mark designs · CPC title

• G03F7/70466

  Multiple exposures, e.g. combination of fine and coarse exposures, double patterning or multiple exposures for printing a single feature (stitching G03F7/70475) · CPC title