Method and Inspection Apparatus and Computer Program Product for Assessing a Quality of Reconstruction of a Value of a Parameter of Interest of a Structure

Patent metadata

Field	Value
Publication number	US-2016154319-A1
Application number	US-201414906898-A
Country	US
Kind code	A1
Filing date	Aug 5, 2014
Priority date	Aug 13, 2013
Publication date	Jun 2, 2016
Grant date	—

Abstract

Methods and inspection apparatus and computer program products for assessing a quality of reconstruction of a value of a parameter of interest of a structure, which may be applied for example in metrology of microscopic structures. It is important the reconstruction provides a value of a parameter of interest (e.g. a CD) of the structure which is accurate as the reconstructed value is used to monitor and/or control a lithographic process. This is a way of assessing a quality of reconstruction ( 803 ) of a value of a parameter of interest of a structure which does not require the use of a scanning electron microscope, by predicting ( 804 ) values of the parameter of interest of structures using reconstructed values of parameters of structures, and by comparing ( 805 ) the predicted values of the parameter of interest and the reconstructed values of the parameter of interest.

First claim

1 . A method of assessing a quality of reconstruction of a value of a parameter of interest of a structure, the method comprising:
for each structure of a set of structures illuminating the structure with one or more beams of radiation and detecting a signal associated with the structure arising from interaction between the radiation and the structure; for each structure of the set of structures reconstructing, from the signal associated with the structure, values of parameters of a mathematical model of the structure, wherein at least one of the parameters is designated as the parameter of interest of the structure; predicting for each structure of the set of structures a value of the parameter of interest of the structure using at least a subset of the reconstructed values of the parameters associated with the set of structures; and comparing the predicted values of the parameter of interest and the reconstructed values of the parameter of interest to assess the quality of reconstruction of a value of the parameter of interest of a structure.

2 . The method of claim 1 , wherein the reconstructing values of parameters of a mathematical model of the structure is in accordance with a model recipe.

3 . (canceled)

4 . The method of claim 1 , wherein the predicting uses means of regression analysis.

5 . (canceled)

6 . The method of claim 1 , wherein the comparing the quality of reconstruction of a value of the parameter of interest of a structure is assessed as higher with increasing dissimilarity between the predicted values of the parameter of interest and the reconstructed values of the parameter of interest.

7 . The method of claim 1 , wherein the output of the comparing the predicted values of the parameter of interest and the reconstructed values of the parameter of interest is a single value, the single value being a metric of the quality of reconstruction of a value of the parameter of interest of a structure.

8 . The method of claim 1 , wherein the comparing uses a normalization based upon the reconstructed values of the parameter of interest.

9 . The method of claim 1 , wherein the predicting uses a common mode suppression of the at least the subset of the reconstructed values of the parameters associated with the set of structures.

10 . The method of claim 1 , wherein the parameters of the mathematical model of the structure comprise parameters describing the shape and material properties of the structure.

11 . (canceled)

12 . The method of claim 1 , wherein the number of parameters of the mathematical model of the structure is greater than 4, or 8, or 16 or 32.

13 .- 15 . (canceled)

16 . The method of claim 1 , wherein the number of structures in the set of structures is greater than 5, or 20, or 100, or 1000.

17 . The method of claim 1 , wherein the structures of the set of structures are essentially identical by design.

18 . (canceled)

19 . The method of claim 2 , the method further comprising repeating the method multiple times each time using a different model recipe.

20 . The method according to claim 19 , wherein the step of for each structure of a set of structures illuminating the structure with one or more beams of radiation and detecting a signal associated with the structure arising from interaction between the radiation and the structure is performed once and the reconstructing, predicting and comparing steps are performed for each different model recipe.

21 . The method according to claim 19 , wherein the mathematical model of the structure and the parameter of interest of the structure are the same during each repetition of the method.

22 . The method according to claim 19 , further comprising determining a model recipe from the different model recipes used in the method which has, compared to other model recipes used in the method, a high quality of reconstruction of a value of the parameter of interest of a structure.

23 . The method of claim 1 , wherein the predicting and the comparing are performed essentially in a same mathematical step.

24 . The method of claim 2 , the method further comprising altering the model recipe based on the assessment of the quality of reconstruction of a value of the parameter of interest of a structure.

25 . An inspection apparatus for assessing a quality of reconstruction of a value of a parameter of interest of a structure, the apparatus comprising:
an illumination system configured to illuminate each structure of a set of structures with one or more beams of radiation; a detection system configured to detect for each structure of the set of structures a signal associated with the structure arising from interaction between the radiation and the structure; and a processor, wherein the processor is arranged to for each structure of the set of structures reconstruct, from the signal associated with the structure, values of parameters of a mathematical model of the structure, wherein at least one of the parameters is designated as the parameter of interest of the structure, wherein the processor is arranged to predict for each structure of the set of structures a value of the parameter of interest of the structure using at least a subset of the reconstructed values of the parameters associated with the set of structures, and wherein the processor is arranged to compare the predicted values of the parameter of interest and the reconstructed values of the parameter of interest to assess the quality of reconstruction of a value of the parameter of interest of a structure.

26 . A computer program product containing one or more sequences of machine-readable instructions for assessing a quality of reconstruction of a value of a parameter of interest of a structure, the instructions being adapted to cause one or more processors to:
for each structure of a set of structures receive a detected signal associated with the structure arising from interaction between radiation and the structure under predetermined illumination; for each structure of the set of structures reconstruct, from the signal associated with the structure, values of parameters of a mathematical model of the structure, wherein at least one of the parameters is designated as the parameter of interest of the structure; predict for each structure of the set of structures a value of the parameter of interest of the structure using at least a subset of the reconstructed values of the parameters associated with the set of structures; and compare the predicted values of the parameter of interest and the reconstructed values of the parameter of interest to assess the quality of reconstruction of a value of the parameter of interest of a structure.

Assignees

• Asml Netherlands Bv
• Asml Netherlands Bv

Inventors

• Mossavat Seyed Iman
• Cramer Hugo Augustinus Joseph
• Grootjans Willem Jan
• Van Leest Adriaan Johan

Classifications

• G03F7/705 Primary

  Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions · CPC title

• G01N21/956 Primary

  Inspecting patterns on the surface of objects {(contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)} · CPC title

• G03F9/7092

  Signal processing · CPC title

• G01N21/95607

  using a comparative method · CPC title

• G03F7/70625

  Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness · CPC title