Metrology test structure design and measurement scheme for measuring in patterned structures

Patent metadata

Field	Value
Publication number	US-10359369-B2
Application number	US-201515502329-A
Country	US
Kind code	B2
Filing date	Aug 6, 2015
Priority date	Aug 7, 2014
Publication date	Jul 23, 2019
Grant date	Jul 23, 2019

Abstract

A test structure is presented for use in metrology measurements of a sample pattern. The test structure comprises a main pattern, and one or more auxiliary patterns. The main pattern is formed by a plurality of main features extending along a first longitudinal axis and being spaced from one another along a second lateral axis. The one or more auxiliary patterns are formed by a plurality of auxiliary features associated with at least some of the main features such that a dimension of the auxiliary feature is in a predetermined relation with a dimension of the respective main feature. This provides that a change in a dimension of the auxiliary feature from a nominal value affects a change in non-zero order diffraction response from the test structure in a predetermined optical measurement scheme, and this change is indicative of a deviation in one or more parameters of the main pattern from nominal value thereof.

First claim

The invention claimed is:

1. A test structure for use in metrology measurements of a sample pattern, the test structure comprising:
a main pattern formed by a plurality of main features extending along a first longitudinal axis and being spaced from one another along a second lateral axis; and
a plurality of auxiliary features defining at least one auxiliary pattern, the auxiliary features being associated with at least some of the main features such that a dimension of the auxiliary feature is in a predetermined relation with a dimension of the respective main feature, thereby providing that a change in said dimension of the auxiliary feature from a nominal value affects a change in non-zero order diffraction response from the test structure in a predetermined optical measurement scheme, said change being thus indicative of a deviation in one or more parameters of the main pattern from nominal value thereof, the auxiliary features of the auxiliary pattern being arranged in a spaced-apart relationship along said second lateral axis, a periodicity of the auxiliary pattern being significantly larger than periodicity of the main pattern, the auxiliary feature of the auxiliary pattern comprising a groove of a substantially V-shaped cross section between two locally adjacent features of the main pattern, a lateral dimension of the groove reducing along a depth of the groove from a top surface of said main pattern according to a predetermined function.

2. The test structure according to claim 1 , wherein the main features of the main pattern comprise grooves spaced by projections, said auxiliary features being associated with the some of the grooves, modifying them to form said V-shaped cross section.

3. The test structure according to claim 1 , wherein said non-zero order of diffraction includes at least one of first and second orders of diffraction.

4. The test structure according to claim 1 , wherein said main features are lines arranged with spaces between them.

5. The test structure according to claim 1 , configured for controlling a patterning process applied to the sample by monitoring the change of said dimension of the main pattern from the nominal value, said change being indicative of a corresponding deviation of one or more parameters of the sample pattern from the nominal value.

6. A sample comprising a sample pattern and at least one test site, the test site comprising the test structure according to claim 1 .

7. The sample according to claim 6 , being a semiconductor wafer.

8. The sample according to claim 7 , wherein said at least one test site is located in a scribe line of the sample pattern.

9. A method for use in measurements of a sample pattern, the method comprising:
providing a test structure according to claim 1 ;
performing an optical measurement on said test structure and detecting at least one non-zero order diffractive response from the test structure, and generating measured data indicative of said at least one non-zero order diffractive response; and
processing and analyzing said measured data, and upon identifying a change in the diffractive response, generating data indicative of deviation of one or more parameters of the sample pattern from nominal value.

10. The method according to claim 9 , for controlling a patterning process applied to the sample to create said sample pattern.

11. The method according to claim 10 , wherein said patterning process comprises at least two sequential patterning stages sequentially creating at least two array of feature forming together said sample pattern.

12. A test structure for use in metrology measurements of a sample pattern, the test structure comprising:
a main pattern formed by a plurality of main features extending along a first longitudinal axis and being spaced from one another along a second lateral axis; and
a plurality of auxiliary features defining at least one auxiliary pattern, the auxiliary features being associated with at least some of the main features such that a dimension of the auxiliary feature is in a predetermined relation with a dimension of the respective main feature, thereby providing that a change in said dimension of the auxiliary feature from a nominal value affects a change in non-zero order diffraction response from the test structure in a predetermined optical measurement scheme, said change being thus indicative of a deviation in one or more parameters of the main pattern from nominal value thereof, wherein the auxiliary features of the auxiliary pattern have one of the following configurations: the auxiliary features of the auxiliary pattern are arranged in said spaced-apart relationship along the first longitudinal axis; the auxiliary features of the auxiliary pattern are located in the features of the main pattern and are configured such that the lateral dimension of the auxiliary feature matches the lateral dimension of the respective feature of the main pattern.

13. A sample comprising a sample pattern and at least one test site, the test site comprising the test structure according to claim 12 .

14. The test structure for use in metrology measurements of a sample pattern, the test structure comprising:
a main pattern formed by a plurality of main features extending along a first longitudinal axis and being spaced from one another along a second lateral axis; and
a plurality of auxiliary features defining at least one auxiliary pattern, the auxiliary features being associated with at least some of the main features such that a dimension of the auxiliary feature is in a predetermined relation with a dimension of the respective main feature, thereby providing that a change in said dimension of the auxiliary feature from a nominal value affects a change in non-zero order diffraction response from the test structure in a predetermined optical measurement scheme, said change being thus indicative of a deviation in one or more parameters of the main pattern from nominal value thereof, wherein said plurality of the auxiliary features defines at least one additional auxiliary pattern, thereby forming at least first and second auxiliary patterns associated with, respectively, said first and second sub-patterns, the auxiliary features of each of said at least first and second auxiliary patterns being arranged in a spaced-apart relationship along the first axis with periodicity significantly larger than a periodicity of the main features of the same sub-pattern along the second axis, and the first and second auxiliary patterns being shifted with respect to each other by a predetermined distance along said first axis.

15. The test structure according to claim 14 , wherein the auxiliary patterns have the same periodicity.

16. The test structure according to claim 15 , wherein said shift by the predetermined distance is selected to be approximately equal to half of the periodicity of the auxiliary pattern.

17. The test structure according to claim 14 , wherein a change in the lateral dimension of the auxiliary feature of one of said at least first and second auxiliary patterns with respect to that of the other auxiliary pattern affects the non-zero order diffraction response from the test structure, being thus indicative of a change in the lateral dimension of the main feature from the nominal value.

18. The test structure according to claim 14 , wherein said at least first and second shifted auxiliary patterns define a combined pattern having a unit cell, a change in the lateral dimension of the auxiliary feature of the one of the at least first and second auxiliary patterns

Assignees

• Nova Measuring Instr Ltd

Inventors

• Barak Gilad
• Cohen Oded

Classifications

• H10P74/27

  Structural arrangements therefor · CPC title

• H10W46/00

  Marks applied to devices, e.g. for alignment or identification · 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

• G01B2210/56

  Measuring geometric parameters of semiconductor structures, e.g. profile, critical dimensions or trench depth · CPC title

• G01B11/14

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