Measuring a Process Parameter for a Manufacturing Process Involving Lithography

Patent metadata

Field	Value
Publication number	US-2016349627-A1
Application number	US-201515117409-A
Country	US
Kind code	A1
Filing date	Jan 28, 2015
Priority date	Feb 21, 2014
Publication date	Dec 1, 2016
Grant date	—

Abstract

There is disclosed a method of measuring a process parameter for a manufacturing process involving lithography. In a disclosed arrangement the method comprises performing first and second measurements of overlay error in a region on a substrate, and obtaining a measure of the process parameter based on the first and second measurements of overlay error. The first measurement of overlay error is designed to be more sensitive to a perturbation in the process parameter than the second measurement of overlay error by a known amount.

First claim

1 . A method of measuring a process parameter for a manufacturing process involving lithography, comprising:
performing first and second measurements of overlay error in a region on a substrate; and obtaining a measure of the process parameter based on the first and second measurements of overlay error, wherein the first measurement of overlay error is designed to be more sensitive to a perturbation in the process parameter than the second measurement of overlay error by a known amount.

2 . The method according to claim 1 , wherein the process parameter comprises an asymmetry in a feature of a target structure formed on the substrate by a lithographic process.

3 . The method according to claim 2 , wherein the asymmetry in a feature comprises an asymmetry in the cross-sectional shape of a line or trench in a line grating of the target structure, the asymmetry being defined with respect to a mirror plane cutting through the center of the line or trench when viewed along the line or trench, and extending perpendicular to the plane of the grating.

4 . The method according to claim 3 , wherein the asymmetry in a feature comprises an asymmetry in the angles of side-walls defining a line in the line grating relative to a normal to the plane of the grating.

5 . The method according to claim 3 , wherein the asymmetry in a feature comprises a tilt in the floor of a trench formed between lines of the line grating.

6 . The method according to claim 1 , wherein simulation of the first and second measurements of overlay error is used to design the first measurement of overlay error to be more sensitive to a perturbation in the process parameter than the second measurement of overlay by a known amount.

7 . The method according to claim 1 , wherein:
the first and second measurements of overlay error use different target structures, the method of measuring the target structures and the target structures themselves being configured such that the first measurement of the overlay error is more sensitive to a perturbation in the process parameter than the second measurement of the overlay error by a known amount.

8 . The method according to claim 1 , wherein:
the first measurement of overlay error uses radiation having first wavelength characteristics and first polarization characteristics to measure the overlay error of a target structure, and the second measurement of overlay error uses radiation having second wavelength characteristics and second polarization characteristics to measure the overlay error of the same target structure, the first wavelength characteristics are different to the second wavelength characteristics, or the first polarization characteristics are different to the second polarization characteristics, or both.

9 . The method according to claim 1 , wherein the first and second measurements of overlay error use one or more target structures comprising a line grating.

10 . The method according to claim 1 , wherein the process parameter comprises a variation from a reference value of one or more of the following: etch depth of a feature formed on the substrate, thickness of a layer or feature formed on the substrate, relative permittivity of material forming a layer or feature on the substrate, refractive index of material forming a layer or feature on the substrate.

11 . A computer readable product comprising machine-readable instructions for causing a processor to perform the operations step of comprising:
performing first and second measurements of overlay error in a region on a substrate; and obtaining a measure of the process parameter based on the first and second measurements of overlay error, wherein the first measurement of overlay error is designed to be more sensitive to a perturbation in the process parameter than the second measurement of overlay error by a known amount.

12 . An inspection apparatus for measuring a process parameter for a manufacturing process involving lithography, comprising:
an optical system arranged to direct radiation onto a substrate; a detector arranged to detect radiation after interaction between the radiation and the substrate; an overlay error processing module arranged to obtain a measure of overlay error by analyzing an output from the detector; and a process parameter obtaining module arranged to obtain a measure of the process parameter by causing the optical system, detector and overlay error processing module to:
perform first and second measurements of overlay error in a region on the substrate; and
obtain a measure of the process parameter based on the first and second measurements of overlay error, wherein
the first measurement of overlay error is designed to be more sensitive to a perturbation in the process parameter than the second measurement of overlay error by a known amount.

13 - 14 . (canceled)

15 . A substrate comprising:
target structures comprising a first target structure and a second target structure configured such that a first measurement of overlay error using the first target structure is more sensitive to a perturbation in a process parameter for a manufacturing process involving lithography than a second measurement of overlay error using the second target by a known amount.

16 . A lithographic system comprising:
a lithographic apparatus comprising:
an illumination system arranged to illuminate a pattern;
a projection optical system arranged to project an image of the pattern onto a substrate; and
an inspection apparatus comprising,
an optical system arranged to direct radiation onto a substrate;
a detector arranged to detect radiation after interaction between the radiation and the substrate;
an overlay error processing module arranged to obtain a measure of overlay error by analyzing an output from the detector; and
a process parameter obtaining module arranged to obtain a measure of the process parameter by causing the optical system, detector and overlay error processing module to:
perform first and second measurements of overlay error in a region on the substrate; and
obtain a measure of the process parameter based on the first and second measurements of overlay error, wherein
the first measurement of overlay error is designed to be more sensitive to a perturbation in the process parameter than the second measurement of overlay error by a known amount;

wherein the lithographic apparatus is arranged to use one or more process parameters measured by the inspection apparatus in applying the pattern to the substrate or further substrates.

17 . A method of manufacturing devices wherein a device pattern is applied to a series of substrates using a lithographic process, the method comprising:
measuring a process parameter by inspecting at least one target structure formed as part of or beside said device pattern on a least one of said substrates using a method comprising,
performing first and second measurements of overlay error in a region on a substrate; and
obtaining a measure of the process parameter based on the first and second measurements of overlay error,
wherein the first measurement of overlay error is designed to be more sensitive to a perturbation in the process parameter than the second measurement of overlay error by a known amount; and
controlling the lithographic process for later substrates in accordance with the result of the measuring of the process parameter.

Assignees

• Asml Netherlands Bv

Inventors

• Van Der Schaar Maurits
• Den Boef Arie Jeffrey
• Adam Omer Abubaker Omer
• Huang Te-Chih
• Zhang Youping

Classifications

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H10P76/2041

  Photolithographic processes · 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

• G01N21/8806

  Specially adapted optical and illumination features · CPC title

• G01N21/47 Primary

  Scattering, i.e. diffuse reflection (G01N21/25, G01N21/41 take precedence {G01N21/55 takes precedence}) · CPC title