Test structure for use in metrology measurements of patterns
A test structure and method of its manufacture are presented for use in metrology measurements of a sample pattern. The test structure comprises a test pattern comprising a portion of the sample pattern including at least one selected feature and a blocking layer at least partially covering regions of the test structure adjacent to the at least one selected region.
1. A method for creating a test structure for use in metrology measurements of a sample pattern produced by a predetermined multi-patterning scheme, the method comprising: applying a multi-patterning process to a test site for creating a test pattern based on design rules of the sample pattern and configured to enable focusing the metrology measurements on at least one selected feature of the sample pattern, wherein said multi-patterning process applied to the test site either comprises said multi-patterning scheme and at least one additional patterning stage or comprises said multi-patterning scheme while modifying at least one patterning stage of said multi-patterning scheme, such that said multi-patterning process creates in the test site a part of the sample pattern and at least one blocking layer at least partially blocking features of the sample pattern adjacent to said at least one selected feature.
2. The method of claim 1 , wherein said at least one blocking layer comprises a continuous layer within a region between a pair of the selected features.
3. The method of claim 1 , wherein said at least one blocking layer comprises blocking elements arranged in a spaced-apart regions along said at least one selected feature.
4. The method of claim 1 , wherein said creating of the at least one blocking layer comprises applying material deposition on at least one region of the test structure.
5. The method of claim 1 , wherein said creating of the at least one blocking layer comprises applying material removal to at least one region of the test structure.
6. The method of claim 1 , wherein said multi-patterning process applied to the test site is configured to modify a complex structure of the sample pattern with respect to said at least one selected feature into the test pattern having a simpler structure with respect to said at least one selected feature.
7. The method of claim 1 , wherein said test structure resulting from said multi-patterning process comprises an array of at least two spaced patterned regions, each being a portion of the unit cell of the sample pattern including, at least partially, said at least one selected feature.
8. The method of claim 1 , comprising determining said multi-patterning process by processing and analyzing input data comprising: data indicative of the rule design of the sample pattern, data indicative of the multi-patterning scheme, and data indicative of said at least one selected feature on which the metrology measurements are to be focused.
9. The method of claim 1 , wherein said multi-patterning process is further configured to induce a known parameter difference between the selected features in the test pattern, thereby enabling self-calibration of metrology measurements.
10. The method of claim 1 , wherein said multi-patterning process is applied to the test site concurrently with applying said multi-patterning scheme to a pattern region of the sample to create the sample pattern in the pattern region.
11. The method of claim 10 , wherein said multi-patterning process is applied to the test site located in a test region of the sample outside said pattern region.
12. The method of claim 10 , wherein said multi-patterning process is applied to the test site located in a test region of the sample within a scribe line of the pattern region.
13. The method of claim 1 , wherein the unit cell of the sample pattern comprises an array of alternating lines and spaces.
14. The method of claim 1 , wherein the multi-patterning scheme includes at least one of Litho-Etch-Litho-Etch (LELE) scheme, Spacer Assisted Double Patterning (SADP) scheme, and Spacer Assisted Quadra Patterning (SADP) scheme.
15. A test structure for use in metrology measurements of a sample pattern, the test structure being created by the method of claim 1 .
16. A test structure for use in metrology measurements of a sample pattern, the test structure comprising a test pattern comprising a portion of the sample pattern including at least one selected feature of the sample pattern and a blocking layer at least partially covering regions of the test structure adjacent to said at least one selected region.
17. The method of claim 1 , wherein said multi-patterning process applied to the test site is configured to modify a complex structure of the sample pattern with respect to said at least one selected feature into the test pattern having a simpler structure with respect to said at least one selected feature, the test pattern comprising an array of at least two spaced patterned regions, each being a portion of the unit cell of the sample pattern including, at least partially, said at least one selected feature.
18. A sample comprising a pattern region having a sample pattern and a test site comprising a test structure having a test pattern, wherein the test structure is created by the method of claim 1 , such that the multi-patterning process is applied to the test site concurrently with applying the multi-patterning scheme to the pattern region of the sample to create the sample pattern in the pattern region, the test site having one of the following configurations: the test site is located in a test region of the sample outside said pattern region; or the test site is located in a test region of the sample within a scribe line of the pattern region.