DESIGN LAYOUT PATTERN PROXIMITY CORRECTION THROUGH FAST EDGE PLACEMENT ERROR PREDICTION

• US 20180157161A1
• Filed: 12/01/2016
• Published: 06/07/2018
• Est. Priority Date: 12/01/2016
• Status: Active Application

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Mailfert, Julien, Sriraman, Saravanapriyan, Tetiker, Mehmet Derya
• Granted Patent: US 10,254,641 B2
• Time in Patent Office: Days
• CPC Class Codes: G03F 1/36 Masks having proximity correction features; Preparation thereof, e.g. optical proximity correction [OPC] design processes
• CPC Class Codes: G06F 30/367 Design verification, e.g. using simulation, simulation program with integrated circuit emphasis [SPICE], direct methods or relaxation methods
• CPC Class Codes: G06F 30/398 Design verification or optimisation, e.g. using design rule check [DRC], layout versus schematics [LVS] or finite element methods [FEM] optical proximity correction [OPC] design processes G03F1/36

Abstract

Disclosed are methods of generating a proximity-corrected design layout for photoresist to be used in an etch operation. The methods may include identifying a feature in an initial design layout, and estimating one or more quantities characteristic of an in-feature plasma flux (IFPF) within the feature during the etch operation. The methods may further include estimating a quantity characteristic of an edge placement error (EPE) of the feature by comparing the one or more quantities characteristic of the IFPF to those in a look-up table (LUT, and/or through application of a multivariate model trained on the LUT, e.g., constructed through machine learning methods (MLM)) which associates values of the quantity characteristic of EPE with values of the one or more quantities characteristics of the IFPF. Thereafter, the initial design layout may be modified based on at the determined quantity characteristic of EPE.

Claims

1. A method of generating a look-up table (LUT) associating, for a plurality of features on a semiconductor substrate surface, values of one or more quantities characteristic of an edge placement error (EPE) with values of one or more quantities characteristic of in-feature plasma flux (IFPF), the features to be etched into a material stack on said substrate via a plasma-based etch process performed in a processing chamber under a set of process conditions, the method comprising:

(a) receiving the set of process conditions and the material stack composition;

(b) receiving a pattern of photoresist defining a set of features;

(c1) calculating a first IFPF-characteristic (IFC) value, the first IFC value corresponding to a first quantity characteristic of IFPF during the etch, under the set of process conditions, of a first selected feature from the set of features;

(c2) calculating a second IFC value, the second IFC value corresponding to the first characteristic of IFPF during the etch, under the set of process conditions, of a second selected feature from the set of features;

(d1) including a first entry in the LUT associated with an edge of the first selected feature, the first entry comprising;

the first IFC value; and

a first EPE-characteristic (EPC) value corresponding to a quantity characteristic of an EPE of the edge of the first selected feature, said first EPC value generated by running a computerized etch profile model (EPM) to simulate etching under the set of process conditions of the material stack as overlaid with at least the portion of the pattern of photoresist corresponding to the first selected feature; and

(d2) determining to not include an entry in the LUT associated with an edge of the second selected feature and comprising the second IFC value, the determining based, at least in part, on the similarity of the second IFC value to the first IFC value.

2. The method of claim 1, wherein it is determined in (d2) to not include the entry in the LUT for the second selected feature when the second IFC value is within 5% of the first IFC value.

3. The method of claim 1, wherein it is determined in (d2) to not include the entry in the LUT for the second selected feature when the second IFC value is within 2% of the first IFC value.

4. The method of claim 1, further comprising:

(c3) calculating a third IFC value, the third IFC value corresponding to the first quantity characteristic of IFPF during the etch, under the set of process conditions, of a third selected feature from the set of features; and

(d3) determining to not include an entry in the LUT associated with an edge of the third selected feature and comprising the third IFC value, the determining based, at least in part, on the similarity of the third IFC value to the first IFC value.

5. The method of claim 4, wherein:

in (d2) it is determined to not include the entry in the LUT for the second selected feature when the second IFC value is within 5% of the first IFC value; and

in (d3) it is determined to not include the entry in the LUT for the third selected feature when the third IFC value is within 5% of the first IFC value.

6. The method of claim 1, further comprising:

(c1′

) calculating a third IFC value, the third IFC value corresponding to a second quantity characteristic of IFPF during the etch, under the set of process conditions, of the first selected feature; and

(c2′

) calculating a fourth IFC value, the fourth IFC value corresponding to the second quantity characteristic of IFPF during the etch, under the set of process conditions, of the second selected feature;

wherein;

in (d1), the first entry in the LUT further comprises the third IFC value; and

in (d2), the determining is further based on the similarity of the fourth IFC value to the third IFC value.

7. The method of claim 6, wherein in (d2) it is determined to not include the entry in the LUT for the second selected feature when:

the second IFC value is within 5% of the first IFC value; and

the fourth IFC value is within 5% of the third IFC value.

8. The method of claim 6, wherein in (d2) the determining is based, at least in part, on a distance metric calculated between the first selected feature and the second selected feature, the distance metric calculated by a procedure comprising:

calculating a first difference indicator (DI) value indicative of the difference between the first IFC value and the second IFC value;

calculating a second DI value indicative of the difference between the third IFC value and the fourth IFC value; and

calculating a combined DI value indicative of the sum of the magnitudes of the first DI value and the second DI value.

9. The method of claim 8, wherein in (d2) the determining comprises comparing the distance metric to a reference value.

10. The method of claim 1, wherein in (d2) the determining is further based on the similarity of the first EPC value to a second EPC value, the second EPC value corresponding to a quantity characteristic of an EPE of the edge of the second selected feature, said second EPC value generated by running a computerized etch profile model (EPM) to simulate etching under the set of process conditions of the material stack as overlaid with at least the portion of the pattern of photoresist corresponding to the second selected feature.

11. The method of claim 1, wherein the first quantity characteristic of IFPF is more particularly characteristic of in-feature plasma ion flux (IFPIF).

12. The method of claim 11, wherein the first IFC value is estimated based on a visibility kernel (VC) corresponding to the feature.

13. The method of claim 12, wherein the first IFC is calculated by a procedure comprising estimating the integral of the VC with the ion energy angular distribution function (IEADF) corresponding to one or more plasma ion fluxes (PIF) above the feature.

14. The method of claim 1, wherein the first quantity characteristic of IFPF is more particularly characteristic of in-feature plasma neutral flux (IFPNF).

15. The method of claim 14, wherein the quantity characteristic of IFPNF is a loaded plasma flux above the feature which accounts for the presence of the substrate in the processing chamber.

16. The method of claim 1, wherein in (d2) the determining is further based on:

a sensitivity metric characteristic of the magnitude of variations in the first EPC value which result from changes in the first IFC value; and

/or

a sensitivity metric characteristic of the magnitude of variations in a second EPC value which result from changes in the second IFC value, the second EPC value corresponding to a quantity characteristic of an EPE of the edge of the second selected feature, said value generated by running a computerized etch profile model (EPM) to simulate etching under the set of process conditions of the material stack as overlaid with at least the portion of the pattern of photoresist corresponding to the second selected feature.

17. The method of claim 16, wherein the sensitivity metric characteristic of either or both of the first or second EPC values is calculated by estimating the partial derivative of the quantity characteristic of EPE with respect to the first quantity characteristic of IFPF (d[EPE]/d[IFPF]) evaluated at either the first or second values of the EPC and IFC.

18. The method of claim 17, wherein the sensitivity metric is calculated by a process comprising:

calculating a first difference indicator (DI) value indicative of the difference between the first and second EPC values;

calculating a second DI value indicative of the difference between the first and second IFC values; and

calculating a value indicative of d[EPE]/d[IFPF] by calculating a value indicative of the ratio of the second to the first DI values.

19. The method of claim 18, wherein in (d2) the determining comprises comparing the sensitivity metric to a reference value.

20. The method of claim 19, wherein the first quantity characteristic of IFPF is more particularly characteristic of in-feature plasma ion flux (IFPIF).

21. The method of claim 19, wherein the first quantity characteristic of IFPF is more particularly characteristic of in-feature plasma neutral flux (IFPNF).

22. The method of claim 1, wherein the received set of process conditions include global processing chamber plasma fluxes of ion and/or neutral/radical plasma species.

23. A look-up table (LUT) comprising a plurality of entries corresponding to a plurality of edges of a plurality of features to be etched into a material stack on a semiconductor substrate surface via a plasma-based etch process performed in a processing chamber under a set of process conditions, the entries comprising a plurality of fields, the fields comprising:

an EPE field holding a value of a quantity characteristic of an edge placement error (EPE); and

one or more IFPF fields holding values of one or more quantities characteristic of an in-feature plasma flux (IFPF), the fields selected from;

an IFPIF field for holding a value of a quantity characteristic of in-feature plasma ion flux (IFPIF);

an IFPNF field for holding a value of a quantity characteristic of in-feature plasma neutral flux (IFPNF); and

an IFPDF field for holding a value of a quantity characteristic of in-feature passivant deposition flux (IFPDF);

wherein the average relative difference between pairs of nearest values held in fields of the table corresponding to each quantity characteristic of IFPF is greater than 5%.

24. A method of identifying a subset of entries from a set of potential entries for use in a look-up table (LUT) or other framework for characterizing an etch process, the entries corresponding to a plurality of edges of a plurality of features to be etched into a material stack on a semiconductor substrate surface via a plasma-based etch process performed in a processing chamber under a set of process conditions, each entry comprising:

a value of a quantity characteristic of an edge placement error (EPE) of an edge of a feature; and

a value of a quantity characteristic of an in-feature plasma flux (IFPF) during said etching of the feature;

the method comprising;

for each potential entry, calculating a sensitivity metric for the entry, the sensitivity metric indicative of the magnitude of the partial derivative of the quantity characteristic of EPE with respect to the quantity characteristic of IFPF (d[EPE]/d[IFPF]) evaluated at the value of the quantity characteristic of IFPF; and

selecting a subset of entries from the set of potential entries such that the average of the sensitivity metric over the subset is higher than the average of the sensitivity metric over the full set.

25. The method of claim 24, wherein said value of the quantity characteristic of the EPE of each entry is generated by running a computerized etch profile model (EPM) to simulate etching under the set of process conditions of the material stack as overlaid with at least the portion of the pattern of photoresist corresponding to a particular feature.

26. The method of claim 24, wherein the subset of entries is selected such that of the 25% of the entries in the full set having the highest sensitivity metrics, at least 5% are included in the sub set.

27. The method of claim 24, wherein the subset of entries is selected such that of the 10% of the entries in the full set having the highest sensitivity metrics, at least 2% are included in the subset.

28. The method of claim 24, wherein the subset of entries is selected such that when the subset is sorted based on the quantity characteristic of IFPF, the density of entries in the subset (relative to the quantity characteristic of IFPF) changes in proportion to the average sensitivity metric (calculated over the group of entries within the subset used to estimate the density) over at least about 75% of the entries selected for the subset.

29. The method of claim 24, wherein the quantity characteristic of IFPF is selected from:

an in-feature plasma ion flux (IFPIF);

an in-feature plasma neutral flux (IFPNF); and

an in-feature passivant deposition flux (IFPDF).

30. A method of detecting high sensitivity regions in a plurality of features to be etched into a material stack on a semiconductor substrate surface via a plasma-based etch process performed in a processing chamber under a set of process conditions, a high sensitivity region corresponding to an edge of a feature which is particularly sensitive to etch process conditions, the method comprising:

choosing a plurality of potential high sensitivity regions in the plurality of features, each potential high sensitivity region corresponding to a particular edge of a feature;

for each potential high sensitivity region, calculating a sensitivity metric corresponding to the particular edge associated with the potential high sensitivity region, the sensitivity metric indicative of the magnitude of an estimated partial derivative of a quantity characteristic of an edge placement error (EPE) corresponding to the edge with respect to a quantity characteristic of an in-feature plasma flux (IFPF) corresponding to the feature, said partial derivative estimated with respect to a value of said quantity characteristic of IFPF corresponding to the feature and chosen process conditions; and

identifying high sensitivity regions in the plurality of potential high sensitivity regions based on the sensitivity metric.