Metrology mark structure and method of determining metrology mark structure

Patent metadata

Field	Value
Publication number	US-12585201-B2
Application number	US-202017765214-A
Country	US
Kind code	B2
Filing date	Sep 25, 2020
Priority date	Oct 14, 2019
Publication date	Mar 24, 2026
Grant date	Mar 24, 2026

Abstract

A structure of a semiconductor device with a sub-segmented grating structure as a metrology mark and a method for configuring the metrology mark. The method for configuring a metrology mark may be used in a lithography process. The method may include determining an initial characteristic function of an initial metrology mark disposed within a layer stack. The method also includes perturbing one or more variables of the plurality of subsegments of the metrology mark (e.g., pitch, duty cycle, and/or line width of the plurality of subsegments) and further perturbing a thickness of one or more layers within the layer stack. The method further includes iteratively performing the perturbations until a minimized characteristic function of an initial metrology mark is determined to set a configuration for the plurality of subsegments.

First claim

The invention claimed is:

1 . A method comprising:
a) obtaining an initial version of a characteristic function of an initial version of a metrology mark disposed within a layer stack for use in a lithography process, the initial version of the metrology mark comprising a plurality of mark segments, at least one of the mark segments comprising a plurality of subsegments, wherein the characteristic function comprises:
a change in a wavelength of a reflected beam with respect to the wavelength of an incident radiation as a function of a change in thickness of the layer stack, the reflected beam being a beam reflected from the metrology mark and passing through the layer stack, or
a change in angular reflectance of the reflected beam as a function of a change in thickness of the stack;
b) perturbing one or more variables of the plurality of subsegments, wherein the one or more variables comprise pitch, duty cycle, and/or line width of the plurality of subsegments; c) perturbing a thickness of one or more layers within the layer stack; d) updating, by a hardware computer, the characteristic function based upon the perturbations of b) and c); e) iteratively performing steps b), c) and d) until a further version of the characteristic function is determined to set a configuration for the plurality of subsegments; and f) physically creating a metrology mark instance having the configuration for the plurality of subsegments, physically creating a patterning device to create at least part of the metrology mark instance, or providing a signal representing, or based on, the configuration for the plurality of subsegments to a tool or system for use by the tool or system to enable creation of the metrology mark instance or of the patterning device.

2 . The method of claim 1 , wherein the characteristic function comprises the change in a wavelength of a reflected beam with respect to the wavelength of an incident radiation as a function of a change in thickness of the layer stack.

3 . The method of claim 1 , wherein the characteristic function comprises the change in angular reflectance of the reflected beam as a function of a change in thickness of the stack.

4 . The method of claim 1 , wherein the pitch and duty cycle remain constant and wherein the line width of the plurality of subsegments is varied.

5 . The method of claim 1 , wherein the pitch and line width remain constant and wherein the duty cycle of the plurality of subsegments is varied.

6 . The method of claim 1 , wherein the line width and duty cycle remain constant and wherein the pitch of the plurality of subsegments is varied.

7 . The method of claim 1 , wherein e) is performed a predetermined number of times before the further version of the characteristic function is determined.

8 . A computer program product comprising a non-transitory computer readable medium having instructions therein, the instructions, when executed by a computer system, configured to cause the computer system to at least:
a) obtain an initial version of a characteristic function of an initial version of a metrology mark disposed within a layer stack for use in a lithography process, the initial version of the metrology mark comprising a plurality of mark segments, at least one of the mark segments comprising a plurality of subsegments, wherein the characteristic function comprises:
a change in a wavelength of a reflected beam with respect to the wavelength of an incident radiation as a function of a change in thickness of the layer stack, the reflected beam being a beam reflected from the metrology mark and passing through the layer stack, or
a change in angular reflectance of the reflected beam as a function of a change in thickness of the stack;
b) perturb one or more variables of the plurality of subsegments, wherein the one or more variables comprise pitch, duty cycle, and/or line width of the plurality of subsegments; c) perturb a thickness of one or more layers within the layer stack; d) update the characteristic function based upon the perturbations of b) and c); e) iteratively perform b), c) and d) until a further version of the characteristic function is determined to set a configuration for the plurality of subsegments; and f) cause physical creation of a metrology mark instance having the configuration for the plurality of subsegments, cause physical creation of a patterning device to create at least part of the metrology mark instance, or provide a signal representing, or based on, the configuration for the plurality of subsegments to a tool or system for use by the tool or system to enable creation of the metrology mark instance or of the patterning device.

9 . The computer program product of claim 8 , wherein the characteristic function comprises the change in a wavelength of a reflected beam with respect to the wavelength of an incident radiation as a function of a change in thickness of the layer stack.

10 . The computer program product of claim 8 , wherein the characteristic function comprises the change in angular reflectance of the reflected beam as a function of a change in thickness of the stack.

11 . The computer program product of claim 8 , wherein the pitch and duty cycle remain constant and wherein the line width of the plurality of subsegments is varied.

12 . The computer program product of claim 8 , wherein the pitch and line width remain constant and wherein the duty cycle of the plurality of subsegments is varied.

13 . The computer program product of claim 8 , wherein the line width and duty cycle remain constant and wherein the pitch of the plurality of subsegments is varied.

14 . A computer program product comprising a non-transitory computer readable medium having instructions therein, the instructions, when executed by a computer system, configured to cause the computer system to at least:
obtain an initial version of a characteristic function of a metrology mark disposed within a layer stack for use in a lithography process, wherein the characteristic function comprises:
a change in a wavelength of a reflected beam with respect to the wavelength of an incident radiation as a function of a change in thickness of the layer stack, the reflected beam being a beam reflected from the metrology mark and passing through the layer stack, or
a change in angular reflectance of the reflected beam as a function of a change in thickness of the stack;
iteratively perturb one or more variables of the metrology mark and/or of the layer stack and update the characteristic function based upon the perturbation, until a further version of the characteristic function is determined to set a configuration for the metrology mark; and cause physical creation of a metrology mark instance having the configuration for the metrology mark, cause physical creation of a patterning device to create at least part of the metrology mark instance, or provide a signal representing, or based on, the configuration for the metrology mark to a tool or system for use by the tool or system to enable creation of the metrology mark instance or of the patterning device.

15 . The computer program product of claim 14 , wherein the perturbation of one or more variables of the metrology mark and/or of the layer stack comprises perturbation of a thickness of one or more layers within the layer stack.

16 . The computer program product of claim 14 , wherein the characteristic function comprises the change in a wavelength of a reflected beam with respect to the wavelength of an incident radiation as a function of a change in thickness of the lay

Assignees

• Asml Holding Nv
• Asml Netherlands Bv

Inventors

• Elazhary Tamer Mohamed Tawfik Ahmed Mohamed
• Socha Robert John
• Roux Stephen
• Huisman Simon Reinald

Classifications

• G01B11/14

  for measuring distance or clearance between spaced objects or spaced apertures (G01B11/26 takes precedence; rangefinders G01C3/00) · CPC title

• G03F9/7076

  Mark details, e.g. phase grating mark, temporary mark · CPC title

• G03F9/7046

  Strategy, e.g. mark, sensor or wavelength selection · 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

• G03F9/7019

  Calibration · CPC title