CN110647008B - Method for screening SBAR rules - Google Patents
Method for screening SBAR rules Download PDFInfo
- Publication number
- CN110647008B CN110647008B CN201910914949.5A CN201910914949A CN110647008B CN 110647008 B CN110647008 B CN 110647008B CN 201910914949 A CN201910914949 A CN 201910914949A CN 110647008 B CN110647008 B CN 110647008B
- Authority
- CN
- China
- Prior art keywords
- sbar
- rules
- pattern
- different
- value
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/36—Masks having proximity correction features; Preparation thereof, e.g. optical proximity correction [OPC] design processes
Abstract
The invention relates to a method for screening SBAR rules, which relates to an optical proximity effect correction technology in a semiconductor integrated circuit.A first pattern is provided firstly in the process of screening the SBAR rules, and different SBAR rules are generated around the first pattern to generate a first pattern set with different SBAR rules; then generating optical models under different focuses; then determining the optimal focus value; then determining a threshold value of the light intensity; and finally, simulating the first patterns with different SBAR rules by using the optical model corresponding to the optimal focus value to obtain the focal depth of the first patterns with different SBAR rules, screening out the patterns with the SBAR rules, the focal depth of which is greater than a first threshold value, and taking the corresponding SBAR rules as standby SBAR rules.
Description
Technical Field
The invention relates to an optical proximity correction technology in a semiconductor integrated circuit, in particular to a method for screening an SBAR rule.
Background
At present, with the development of small line width and high integration of semiconductor technology, higher requirements are also put forward on the photolithography process. Particularly, when the size is reduced to 0.18 μm or even below 90 nm, the pitch of the patterns is getting closer and closer, and the influence of the optical interference and diffraction effect on the adjacent patterns causes optical proximity effects such as line-end shortening (line-end shortening), line-end bridging (line-end bridging), line width variation (line width variations), and line corner rounding (line corner rounding) to occur when the patterns on the mask are transferred onto the wafer.
Specifically, in some semiconductor device designs, there are often densely distributed patterns (dense patterns) and sparsely distributed patterns (iso patterns) on different parts of the same chip. When the same chip has both iso and dense pattern areas, the same target dimension line widths of the iso and dense pattern areas will have different actual dimensions, i.e. line width variations defects, after being transferred onto the wafer due to the optical proximity effect.
Because the difference between the exposure energy required by the iso pattern area and the dense pattern area is large, and the process window is small when the CD is required to be changed within an allowable range. SBAR has been a common process window enhancement method for low process nodes. The principle is that diffraction orders of dense patterns are added to continuous diffraction angle distribution of isolated patterns on a pupil, a process window of original isolated patterns is clamped by the effect of imaging two beams of light greatly, and the focusing depth of isolated lines is improved. In fact, this can also be seen as a superposition of the effects of the two patterns. Referring to fig. 1a and 1b, fig. 1a is a schematic diagram of an isolated pattern without adding an SBAR, fig. 1b is a schematic diagram of an isolated pattern with an SBAR, the isolated pattern of fig. 1a can be a Via 110, and the Via layer is a key layer connecting the upper layer and the lower layer (including a CT layer and a Via layer, where the CT layer is used to connect the gate and the metal layer). For via layers, which are typically designed in a square or rectangular pattern, as shown in fig. 1a, for low process nodes, vias are formed as holes that are circular or elliptical as a result of their true exposure to the wafer due to the optical effect of corner rounding. FIG. 1b is a schematic diagram of adding SBAR120 around via 110.
Referring to fig. 2, fig. 2 shows Bossung curve obtained from fig. 1a and 1b, where curve 210 is Bossung curve without SBAR added, and curve 220 is Bossung curve after SBAR is added. It can be clearly seen that the depth of focus is significantly increased after the addition of the SBAR. Increasing the SBAR can make the exposure energy of the iso pattern area and the dense pattern area close, effectively increasing the whole process window.
For isolated patterns, it has been a common approach to increase their process window by SBAR. However, although SBAR can improve the process window of pattern (pattern), it is a tedious task to determine the proper SBAR rule (SBAR rule). At present, it is common practice to design a plurality of different SBAR rules publishing masks (masks), and measure the results on the silicon wafer by CD-SEM after exposure by a lithography machine to determine the final SBAR rule. However, this method not only wastes masks and manpower, but also requires a long development period.
Disclosure of Invention
The invention aims to provide a method for screening SBAR rules, which is used for reducing the number of published masks, saving the masks and manpower and material resources and shortening the development period.
The method for screening the SBAR rule provided by the invention comprises the following steps: s1: providing a first pattern, and generating different SBAR rules around the first pattern to generate a first pattern set with different SBAR rules; s2: generating optical models at different focuses; s3: determining an optimal focus value; s4: determining a threshold value of light intensity according to the anchor pattern; and S5: and (3) simulating the first patterns with different SBAR rules in the step (S1) by using the optical model corresponding to the optimal focal value to obtain the focal depth of the first patterns with different SBAR rules, and screening out the patterns with the SBAR rules, of which the focal depth is greater than a first threshold value.
Further, the SBAR rule in step S1 includes a distance d1 from the closest SBAR to the first pattern, a distance d2 between two adjacent SBARs, and a width w1 of the SBAR.
Further, the different SBAR rules include SBAR rules for different combinations of distance d1, distance d2, and width w1 values.
Furthermore, the different SBAR rules include an SBAR rule in which any one of the values of the distance d1, the distance d2, and the width w1 is fixed, and the other two values are changed.
Further, the first pattern is an isolated pattern or a sparse pattern.
Further, in step S2, light source information and information of the thin film stack structure on the wafer are input into a simulation software, so as to generate optical models at different focal points.
Further, in step S3, the optical intensity distribution of the first pattern with SBAR rule in step S1 at different focuses is extracted, and the optimal focus value is determined according to the optical intensity distribution.
Further, the optimal focal value is a focal value corresponding to the maximum optical intensity distribution among the optical intensity distributions.
Further, in step S4, an optical model corresponding to the optimal focal value is selected according to the optimal focal value determined in step S3, the optical model is used to simulate the optical intensity distribution of the anchor pattern, and the threshold value of the optical intensity is determined according to the post-development CD measurement target value of the anchor pattern.
Furthermore, the optical intensity value in which the difference between two corresponding points of a peak in the optical intensity distribution curve under the same optical intensity value is the CD target value of the Anchor pattern is the threshold value of the optical intensity.
Further, in step S5, CD values under different focus conditions are obtained according to the threshold of the light intensity determined in step S4, so as to obtain Bossung curves of the first patterns with different SBAR rules, an absolute value of curvature is obtained through polynomial fitting, the absolute value of curvature represents the depth of focus, the fitted curvature of each first pattern with SBAR rules in the first pattern set with different SBAR rules in step S1 is counted, and the SBAR rule corresponding to the first pattern with SBAR rules with curvature smaller than the first threshold is selected as the spare SBAR rule.
Furthermore, the method for screening the SBAR rules is applied to screening the SBAR rules applied to optical proximity effect correction.
The method for screening the SBAR rules comprises the steps of providing a first pattern during the process of screening the SBAR rules, and generating different SBAR rules around the first pattern to generate a first pattern set with the different SBAR rules; then generating optical models under different focuses; then determining the optimal focus value; then determining a threshold value of the light intensity; and finally, simulating the first patterns with different SBAR rules by using the optical model corresponding to the optimal focus value to obtain the focal depth of the first patterns with different SBAR rules, screening out the patterns with the SBAR rules, the focal depth of which is greater than a first threshold value, and taking the corresponding SBAR rules as standby SBAR rules.
Drawings
FIG. 1a is a schematic diagram of an isolated pattern without adding SBAR.
FIG. 1b is a schematic diagram of an isolated pattern with an added SBAR.
Fig. 2 is the Bossung curve obtained from fig. 1a and 1 b.
Fig. 3 is a schematic diagram of a first pattern generated with SBAR rules.
Fig. 4 is a schematic diagram of optical intensity distributions corresponding to optical models of a first pattern with SBAR rules at different focuses.
FIG. 5 is a diagram illustrating the optical intensity distribution of Anchor pattern under the optical model corresponding to the optimal focal value.
Fig. 6 is a simulated CD value at different focal points.
FIG. 7 is a graph illustrating the curvature of a wafer as a result of comparison with the curvature simulated by the present invention.
Detailed Description
The technical solutions in the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
In an embodiment of the present invention, a method for screening SBAR rules is provided. The method for screening the SBAR rule of the embodiment of the invention comprises the following steps:
s1: providing a first pattern 310, generating different SBAR rules around the first pattern 310 to generate a first pattern set with different SBAR rules;
specifically, in an embodiment of the present invention, the SBAR rule includes a distance d1 from the closest SBAR320 to the first pattern 310 from the first pattern 310, a distance d2 between two adjacent SBARs, and a width w1 of the SBAR, please refer to fig. 3, where fig. 3 is a schematic diagram of a first pattern generated with the SBAR rule. Further, in an embodiment of the invention, the different SBAR rules include SBAR rules with different combinations of values of the distance d1, the distance d2 and the width w1. Specifically, referring to tables 1 and 2, tables 1 and 2 show different SBAR rules in 39 for combinations of values of distance d1, distance d2, and width w1.
In an embodiment of the present invention, in order to screen out an optimal SBAR rule, it is preferable that the different SBAR rules include a combination manner of multiple different SBAR rules as much as possible, and specifically, the different SBAR rules include an SBAR rule formed after any one of values of a distance d1, a distance d2, and a width w1 is fixed and the other two values are changed.
In an embodiment of the present invention, the first pattern 310 is an isolated pattern (iso) or a sparse pattern. Of course, the first pattern 310 may be any pattern that requires the addition of SBAR rules to improve its process window.
TABLE 1
TABLE 2
S2: generating an optical model (optical model) at different focal points (focus);
specifically, in an embodiment of the present invention, light source information and Film stack structure (Film stack) information on a wafer are input into a simulation software, so as to generate optical models (optical models) at different focal points (focus).
S3: determining an optimal focus value;
specifically, in an embodiment of the invention, the optical intensity distributions (aeial image) of the first pattern with the SBAR rule in different focuses in step S1 are extracted, please refer to fig. 4, fig. 4 is a schematic diagram of the optical intensity distributions (aeial image) corresponding to the optical model (optical model) of the first pattern with the SBAR rule in different focuses, and as shown in fig. 4, the optimal focus value is determined according to the optical intensity distributions (aeial image). Specifically, in the embodiment of the present invention, the optimal focal point value is the focal point value corresponding to the maximum optical intensity distribution in the optical intensity distributions, as shown in fig. 4, which is the focal point value corresponding to the line 410.
S4: determining a threshold (threshold) of the light intensity according to the anchor pattern;
in an embodiment of the present invention, an optical model corresponding to the optimal focus value is selected according to the optimal focus value determined in step S3, the optical model is used to simulate the optical intensity distribution of the anchor pattern, and the threshold of the optical intensity is determined according to an After-development CD measurement (ADI) target value of the anchor pattern. Specifically, referring to fig. 5, fig. 5 is a schematic diagram of the optical intensity distribution of the Anchor pattern under the optical model corresponding to the optimal focal value, where the X axis shown in fig. 5 is the developed CD size of the Anchor pattern, the Y axis is the optical intensity value, and the difference between two points (X2-X1 =78 nm) where the threshold value (0.2 Lux) of the optical intensity intersects with the optical intensity distribution curve is the CD target value. That is, the optical intensity value in which the difference between two points corresponding to a peak in the optical intensity distribution curve under the same optical intensity value is the CD target value of the Anchor pattern is the threshold of the optical intensity, as shown in fig. 5, the optical intensity is 0.2Lux corresponding to two points X2 and X1 of a peak in the optical intensity distribution curve, and X2-X1=78nm is the CD target value of the Anchor pattern, and then 0.2Lux is the threshold of the optical intensity.
S5: and (3) simulating the first patterns with different SBAR rules in the step (S1) by using the optical model corresponding to the optimal focal value to obtain the focal Depth (DOF) of the first patterns with different SBAR rules, and screening out the patterns with the SBAR rules, of which the focal depth is greater than a first threshold value.
Specifically, in an embodiment of the present invention, CD values under different focus conditions are obtained according to the threshold (threshold) of the light intensity determined in step S4, so as to obtain Bossung curves of the first patterns with different SBAR rules, an absolute value of curvature is obtained through polynomial fitting, where the absolute value of curvature represents a depth of focus (DOF), a fitted curvature of each first pattern with SBAR rules in the first pattern set with different SBAR rules in step S1 is counted, and an SBAR rule corresponding to the first pattern with SBAR rules with a curvature smaller than the first threshold is selected as a spare SBAR rule.
Specifically, please refer to table 3, wherein table 3 shows curvature values corresponding to different first patterns with SBAR rules.
TABLE 3
Referring to fig. 6, fig. 6 shows simulated CD values at different focuses, wherein a curve 610 corresponds to the simulated CD value and a curve 620 is a quadratic curve fitting result. For example, as shown in fig. 6, the absolute value of curvature obtained by polynomial fitting is 4325, and the larger the curvature, the smaller the focal depth, and the absolute value of curvature indicates the size of the focal depth. The fitting curvatures of the 39 SBAR rules in step S1 are counted, and as shown in table 3, the SBAR rule with a curvature less than 1500 is selected as the final spare SBAR rule. Of course, the first threshold (e.g. 1500) may be changed according to the requirements of the actual process, and the invention is not limited thereto.
In an embodiment of the present invention, the method for screening SBAR rules is applied to screening SBAR rules applied in optical proximity correction
As described above, in the process of screening the SBAR rules, a first pattern is provided first, and different SBAR rules are generated around the first pattern to generate a first pattern set with different SBAR rules; then generating optical models under different focuses; then determining the optimal focus value; then determining a threshold value of the light intensity; and finally, simulating the first patterns with different SBAR rules by using the optical model corresponding to the optimal focus value to obtain the focal depth of the first patterns with different SBAR rules, screening out the patterns with the SBAR rules, the focal depth of which is greater than a first threshold value, and taking the corresponding SBAR rules as standby SBAR rules.
TABLE 4
According to the first pattern publishing mask (mask) with different SBAR rules generated in the step S1, the curvature of the first pattern with different SBAR rules is obtained on the wafer, and the curvature values corresponding to the different first patterns with SBAR rules shown in the table 4 are obtained. Referring to fig. 7, fig. 7 is a schematic diagram illustrating the comparison between the curvature corresponding to the wafer result and the curvature simulated by the present invention, so that the curvature corresponding to the wafer result is positively correlated with the curvature simulated by the present invention. Namely, the curvature of the first pattern with different SBAR rules is really reflected through the simulated curvature of the invention, and the SBAR rules screened by the method for screening the SBAR rules are proved to be better SBAR rules. The SBAR rules screened by the method for screening the SBAR rules can be used as the SBAR rules of isolated graphs or sparse graphs, or the SBAR rules screened by the method for screening the SBAR rules are further screened on the wafer through the publishing mask, so that the number of the publishing mask can be reduced, the mask and manpower and material resources can be saved, and the development period can be shortened.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (12)
1. A method for screening SBAR rules, comprising:
s1: providing a first pattern, and generating different SBAR rules around the first pattern to generate a first pattern set with different SBAR rules;
s2: generating optical models at different focuses;
s3: determining an optimal focus value;
s4: determining a threshold value of the light intensity according to the anchor pattern; and
s5: and (3) simulating the first patterns with different SBAR rules in the step (S1) by using an optical model corresponding to the optimal focal value to obtain the focal depth of the first patterns with different SBAR rules, and screening out the patterns with the SBAR rules, of which the focal depth is greater than a first threshold value.
2. The method of claim 1, wherein the SBAR rule in step S1 includes a distance d1 from the closest SBAR to the first pattern, a distance d2 between two adjacent SBARs, and a width w1 of the SBAR.
3. The method of screening SBAR rules of claim 2, wherein said different SBAR rules comprise SBAR rules for different combinations of distance d1, distance d2, and width w1 values.
4. The method of claim 3, wherein the different SBAR rules include an SBAR rule formed by a fixed value of any one of the distance d1, distance d2 and width w1 values and a changed value of the other two values.
5. The method of screening SBAR rules of claim 1, wherein said first pattern is an isolated pattern or a sparse pattern.
6. The method of claim 1, wherein in step S2, the light source information and the thin film stack structure information on the wafer are input into a simulation software, so as to generate the optical model at different focuses.
7. The method for screening SBAR rules according to claim 1, wherein in step S3, the optical intensity distribution of the first pattern with SBAR rules in step S1 at different focuses is extracted, and the optimal focus value is determined according to the optical intensity distribution.
8. The method for screening SBAR rules of claim 7, wherein the best focus value is the focus value corresponding to the largest of the optical intensity distributions.
9. The method for screening SBAR rules of claim 1, wherein in step S4, an optical model corresponding to the best focus value is selected according to the best focus value determined in step S3, the optical model is used to simulate the optical intensity distribution of the anchor pattern, and the threshold of the optical intensity is determined according to the post-development CD measurement target value of the anchor pattern.
10. The method of claim 9, wherein the optical intensity value of the optical intensity distribution curve with a difference between two corresponding points of a peak under the same optical intensity value is the CD target value of the Anchor pattern is the threshold value of the optical intensity.
11. The method of claim 1, wherein the CD values under different focus conditions are obtained in step S5 according to the threshold of the light intensity determined in step S4, so as to obtain Bossung curves of the first patterns with different SBAR rules, an absolute value of curvature is obtained by polynomial fitting, the absolute value of curvature represents the depth of focus, the fitted curvature of each first pattern with SBAR rules in the first pattern set with different SBAR rules in step S1 is counted, and the SBAR rule corresponding to the first pattern with SBAR rules with curvature smaller than the first threshold is selected as the spare SBAR rule.
12. The method for screening SBAR rules according to claim 1, wherein the method for screening SBAR rules is applied to screening SBAR rules for application in optical proximity effect correction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910914949.5A CN110647008B (en) | 2019-09-26 | 2019-09-26 | Method for screening SBAR rules |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910914949.5A CN110647008B (en) | 2019-09-26 | 2019-09-26 | Method for screening SBAR rules |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110647008A CN110647008A (en) | 2020-01-03 |
| CN110647008B true CN110647008B (en) | 2023-02-03 |
Family
ID=68992736
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910914949.5A Active CN110647008B (en) | 2019-09-26 | 2019-09-26 | Method for screening SBAR rules |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110647008B (en) |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7018746B2 (en) * | 2003-04-15 | 2006-03-28 | International Business Machines Corporation | Method of verifying the placement of sub-resolution assist features in a photomask layout |
| CN100561340C (en) * | 2006-12-04 | 2009-11-18 | 中芯国际集成电路制造(上海)有限公司 | The method of optical close correction |
| WO2016050584A1 (en) * | 2014-10-02 | 2016-04-07 | Asml Netherlands B.V. | Rule-based deployment of assist features |
| CN106527040B (en) * | 2016-12-30 | 2019-10-25 | 上海集成电路研发中心有限公司 | A kind of adding method of secondary graphics |
| CN109459910B (en) * | 2018-11-22 | 2022-03-18 | 上海华力集成电路制造有限公司 | Sub-resolution auxiliary graph setting method for metal layer process hot spots |
-
2019
- 2019-09-26 CN CN201910914949.5A patent/CN110647008B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN110647008A (en) | 2020-01-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7735053B2 (en) | Correction method and correction system for design data or mask data, validation method and validation system for design data or mask data, yield estimation method for semiconductor integrated circuit, method for improving design rule, mask production method, and semiconductor integrated circuit production method | |
| US5965306A (en) | Method of determining the printability of photomask defects | |
| KR102441582B1 (en) | MPC(Mask Process Correction) verification method, and method for fabricating mask comprising the MPC verification method | |
| CN105425532B (en) | Light source mask collaborative optimization method | |
| US7458060B2 (en) | Yield-limiting design-rules-compliant pattern library generation and layout inspection | |
| US10678142B2 (en) | Optical proximity correction and photomasks | |
| KR20170047101A (en) | Method for fabricating mask and semiconductor device using OPC(Optical Proximity Correction) | |
| JP4398852B2 (en) | Method for adjusting mask pattern transmittance to improve process latitude | |
| US11789370B2 (en) | Optical proximity correction and photomasks | |
| US7820346B2 (en) | Method for collecting optical proximity correction parameter | |
| US20080304029A1 (en) | Method and System for Adjusting an Optical Model | |
| JP2012098397A (en) | Program for creating data of mask | |
| KR101175341B1 (en) | Device and method for determining an illumination intensity profile of an illuminator for a lithography system | |
| CN103792785A (en) | Method of subjecting figures with low picture contrast to optical proximity correction | |
| CN110824829A (en) | Method for establishing OPC model and optical proximity correction method | |
| US20090281778A1 (en) | Method and system for identifying weak points in an integrated circuit design | |
| KR100653990B1 (en) | Method for detecting database pattern's fail on the photo mask | |
| US9223911B2 (en) | Optical model employing phase transmission values for sub-resolution assist features | |
| KR20100071409A (en) | Method for detecting weak point | |
| JP2004163472A (en) | Method for designing photomask, photomask, and semiconductor device | |
| CN110647008B (en) | Method for screening SBAR rules | |
| CN108628109B (en) | Photoetching exposure equipment and photoetching exposure method | |
| US6686100B2 (en) | Optical proximity correction method | |
| US9159557B2 (en) | Systems and methods for mitigating print-out defects | |
| Eurlings et al. | 0.11-um imaging in KrF lithography using dipole illumination |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |