Method of adding scatter bars in opc corrections

Abstract

The application discloses a method for adding scattering bars in OPC correction, comprising the following steps: step one, adding a first type of scattering bar in a layout; step two, selecting a hotspot area in the layout which will cause the first type of scattering bar to form an image; step three, in the hotspot area, setting a second type of scattering bar close to the adjacent pattern boundary on the other side of the first type of scattering bar, the second type of scattering bar being opposite to the first type of scattering bar, and adjusting the width of the second type of scattering bar and the distance from the adjacent pattern boundary to eliminate the image of the first type of scattering bar. The application can keep the scattering bar in the hotspot area where the scattering bar image is easy to form and avoid the scattering bar image, without changing the pattern size.

Description

Technical Field

[0001] This invention relates to a semiconductor integrated circuit manufacturing method, and more particularly to a method for adding scattering stripes in optical proximity correction (OPC). Background Technology

[0002] As semiconductor manufacturing processes advance, pattern periods and sizes are continuously decreasing. Reducing the pattern period necessitates the use of higher-resolution light sources for pattern resolution, but this also results in a smaller depth of focus (DOF) range. Therefore, during the OPC process, scattering bars (Sbars) are added to improve the DOF of sparse patterns, such as semi-isolated and isolated patterns. Normally, Sbars do not form images during exposure and thus do not affect the patterns on the layout. Higher resolution light sources have the disadvantage that Sbars become more prone to printing. Furthermore, since the Light Source Mask Coordination Optimization (SMO) stage primarily considers the influence of optical parameters for light source optimization, it lacks precise Sbar printing prediction capabilities. Therefore, after determining the light source conditions and completing the modeling, during the final publication, there may be hotspot structures where Sbars cannot be added due to printing issues. Such unsolvable problems often can only be addressed by increasing the graphic size to increase DOF, but this can lead to a mismatch between the graphic size and the design size, potentially affecting chip performance. In extreme cases, increasing the graphic size may not be the solution, necessitating the re-establishment of lithography conditions. Therefore, the optimization selection and addition method of Sbars plays a crucial role in small-size, high-precision OPC processing.

[0003] like Figure 1 The diagram shown is a flowchart of the existing OPC correction method for adding scattering bars. Figure 1 The flowchart shown mainly describes the processing flow when Sbar printing occurs, including:

[0004] Step S101: Perform OPC modeling. However, in step S101, the OPC modeling data does not include Sbar data at the extreme dimensions.

[0005] Step S102 involves performing OPC correction, which includes adding an Sbar. Normally, the added Sbar cannot be imaged, meaning printing cannot occur. Therefore, step S102 includes the following: OPC correction reveals that Sbar printing is unavoidable.

[0006] Step S103: When Sbar printing is detected, the existing method is to directly delete the Sbar that causes Sbar printing, that is, delete the Sbar to avoid printing, but this will cause hot spot problems. That is, after deleting the Sbar, the graphic in that area will have DOF problems.

[0007] Step S104: To overcome the hotspot problem caused by removing the Sbar, it is necessary to: enlarge the pattern size of the hotspot problem, or even rebuild the photolithography conditions. Enlarging the pattern size can lead to a mismatch between the pattern size and the design size, potentially affecting chip performance. In extreme cases where enlarging the pattern size cannot solve the problem, it is necessary to rebuild the photolithography conditions. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a method for adding scattering bars in OPC correction, which can retain scattering bars in hot spots where scattering bar imaging is prone to occur and can avoid scattering bar imaging, without changing the graphic size.

[0009] To solve the above-mentioned technical problems, the method for adding scattering bars in OPC correction provided by the present invention includes the following steps:

[0010] Step 1: Add the first type of scattering bar to the layout.

[0011] Step 2: Select the hot spot region in the map that will produce an image of the first type of scattering stripe.

[0012] Step 3: In the hot spot area, a second type of scattering bar is set on the other side of the adjacent pattern boundary corresponding to the first type of scattering bar. The second type of scattering bar is the opposite in type to the first type of scattering bar. The imaging of the first type of scattering bar is eliminated by adjusting the width of the second type of scattering bar and the distance between it and the adjacent pattern boundary.

[0013] A further improvement is that, prior to step one, the following is also included:

[0014] During OPC modeling, the first limiting condition for the size of the first type of scattering stripe and the second limiting condition for the size of the second type of scattering stripe are obtained by collecting wafer data of the scattering stripe.

[0015] A further improvement is that, in step two, the size of the first type of scattering stripe in the hotspot region is determined under a first limiting condition.

[0016] A further improvement is that, in the OPC modeling, the first limiting condition for the size of the first type of scattering stripe includes:

[0017] The width of the first type of scattering strip is 1 to 2 times the limit of photomask fabrication;

[0018] The distance between the first type of scattering strip and the boundary of the adjacent pattern is 1 to 3 times the limit value of the photomask fabrication.

[0019] A further improvement is that, in step two, the first limiting condition for the size of the first type of scattering stripe in the hotspot region includes:

[0020] The width of the first type of scattering strip is 1 to 1.5 times the limit of photomask fabrication.

[0021] A further improvement is that, in the hotspot region, the size of the first type of scattering strip cannot be reduced under a first limiting condition, including:

[0022] Reducing the size of the first type of scattering stripe will eliminate the imaging of the first type of scattering stripe, but at the same time it will reduce the depth of focus to a level that does not meet the requirements;

[0023] Alternatively, the reduction of the first type of scattering stripe cannot eliminate the imaging of the first type of scattering stripe.

[0024] A further improvement is that the first type of scattering bar is a positive scattering bar, and the second type of scattering bar is a negative scattering bar. The positive scattering bar is used to be added to the outside of the graphic, and the negative scattering bar is used to be added to the inside of the graphic.

[0025] Alternatively, the first type of scattering bar is a negative scattering bar, and the second type of scattering bar is a positive scattering bar.

[0026] A further improvement is that, in step three, the size of the second type of scattering strip is set according to the second limiting condition, including:

[0027] The width of the second type of scattering strip is 1 to 2 times the limit of photomask fabrication;

[0028] The distance between the second type of scattering strip and the boundary of the adjacent pattern is 1 to 3 times the limit value of the photomask fabrication.

[0029] After adding a first type of scattering bar to the layout, this invention selects a hotspot region that will produce the first type of scattering bar image. A second type of scattering bar is then set on the opposite side of the adjacent graphic boundary of the first type of scattering bar within the hotspot region. Since the second type of scattering bar is the opposite in type to the first type, the image of the first type of scattering bar can be eliminated by the width of the second type of scattering bar and its distance from the adjacent graphic boundary. Therefore, this invention eliminates the image produced by the first type of scattering bar without deleting it, and it does not require changing the graphic size. Thus, this invention can retain scattering bars in hotspot regions prone to scattering bar imaging and avoid scattering bar imaging without changing the graphic size. Attached Figure Description

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0031] Figure 1 This is a flowchart of the existing OPC correction method for adding scattering bars;

[0032] Figure 2 This is a flowchart of the method for adding scattering bars in OPC correction according to an embodiment of the present invention;

[0033] Figure 3A This is the layout and exposure simulation diagram corresponding to the first type of pattern in the hot spot area of ​​the method for adding scattering bars in OPC correction according to the embodiments of the present invention;

[0034] Figure 3B This is the method for adding scattering bars in the OPC correction of the embodiment of the present invention. Figure 3A The layout and exposure simulation diagrams corresponding to the first type of graphic after adding the second type of scattering bars;

[0035] Figure 4A This is the layout and exposure simulation diagram corresponding to the second type of pattern of the hot spot area in the method of adding scattering bars in OPC correction according to the embodiment of the present invention;

[0036] Figure 4B This is the method for adding scattering bars in the OPC correction of the embodiment of the present invention. Figure 4A The layout and exposure simulation diagram corresponding to the first type of graphic after adding the second type of scattering strips according to the first size condition;

[0037] Figure 4C This is the method for adding scattering bars in the OPC correction of the embodiment of the present invention. Figure 4A The layout and exposure simulation diagram corresponding to the first type of graphic shown are obtained by adding a second type of scattering bar under the second size condition;

[0038] Figure 4DThis is the method for adding scattering bars in the OPC correction of the embodiment of the present invention. Figure 4A The first graphic shown is the layout and exposure simulation diagram after adding the second type of scattering strips according to the third size condition. Detailed Implementation

[0039] like Figure 2 The diagram shown is a flowchart of a method for adding scattering bars in OPC correction according to an embodiment of the present invention. The method for adding scattering bars in OPC correction according to an embodiment of the present invention includes the following steps:

[0040] In this embodiment of the invention, before step one, a further step is performed. Figure 2 Step S201, as shown, involves adding Sbar data under extreme dimensions to the OPC modeling data, including:

[0041] During OPC modeling, the first limiting condition for the size of the first type of scattering bar and the second limiting condition for the size of the second type of scattering bar are obtained by collecting wafer data of the scattering bar. Data corresponding to the Sbar under these limiting conditions, i.e., the first and second limiting conditions, are collected from the wafer data.

[0042] When modeling the OPC, the first limiting condition for the size of the first type of scattering stripe includes:

[0043] The width of the first type of scattering strip is 1 to 2 times the limit of photomask fabrication;

[0044] The distance between the first type of scattering strip and the boundary of the adjacent pattern is 1 to 3 times the limit value of the photomask fabrication.

[0045] Step 1: Add the first type of scattering bar to the layout.

[0046] Step 2: Select the hot spot region in the map that will produce an image of the first type of scattering stripe. Figure 2 Step S202 includes steps one and two, and finally achieves: OPC correction discovers Sbar printing.

[0047] In this embodiment of the invention, in step two, the size of the first type of scattering stripe in the hotspot region is subject to a first limiting condition. Preferably, in step two, the first limiting condition for the size of the first type of scattering stripe in the hotspot region includes:

[0048] The width of the first type of scattering strip is 1 to 1.5 times the limit of photomask fabrication.

[0049] In the hotspot region, the size of the first type of scattering strip cannot be reduced under a first limiting condition, including:

[0050] Reducing the size of the first type of scattering stripe will eliminate the imaging of the first type of scattering stripe, but at the same time it will reduce the depth of focus to a level that does not meet the requirements.

[0051] Alternatively, the reduction of the first type of scattering stripe cannot eliminate the imaging of the first type of scattering stripe.

[0052] Step 3: In the hot spot area, a second type of scattering bar is set on the other side of the adjacent pattern boundary corresponding to the first type of scattering bar. The second type of scattering bar is the opposite in type to the first type of scattering bar. The imaging of the first type of scattering bar is eliminated by adjusting the width of the second type of scattering bar and the distance between it and the adjacent pattern boundary.

[0053] In this embodiment of the invention, setting the size of the second type of scattering strip according to the second limiting condition includes:

[0054] The width of the second type of scattering strip is 1 to 2 times the limit of photomask fabrication;

[0055] The distance between the second type of scattering strip and the boundary of the adjacent pattern is 1 to 3 times the limit value of the photomask fabrication.

[0056] Step 3 corresponds to Figure 2 Step S203 in the text is: adding a limit size inverted Sbar to avoid sbar printing.

[0057] In this embodiment of the invention, the first type of scattering bar is a positive scattering bar, and the second type of scattering bar is a negative scattering bar. The positive scattering bar is added to the outside of the graphic, and the negative scattering bar is added to the inside of the graphic. In other embodiments, the first type of scattering bar can also be a negative scattering bar, and the second type of scattering bar can be a positive scattering bar.

[0058] In this embodiment of the invention, after adding a first type of scattering bar to the layout, a hotspot region that will generate the first type of scattering bar image is selected. A second type of scattering bar is then set on the opposite side of the adjacent graphic boundary of the first type of scattering bar within the hotspot region. Since the second type of scattering bar is the opposite in type to the first type, the image generated by the first type of scattering bar can be eliminated by the width of the second type of scattering bar and its distance from the adjacent graphic boundary. Therefore, this embodiment of the invention does not require deleting the first type of scattering bar to eliminate the image generated by it, and it does not require changing the graphic size. Thus, this embodiment of the invention can retain scattering bars in hotspot regions prone to scattering bar imaging and avoid scattering bar imaging, without changing the graphic size.

[0059] The method of adding scattering bars in OPC correction according to an embodiment of the present invention is explained below using two specific graphics:

[0060] like Figure 3A This is the layout and exposure simulation diagram corresponding to the first type of graphic in the OPC correction method of the present invention; the layout 101 has graphic 103 and the added first type of scattering bar 102. It can be seen that the first type of scattering bar 102 is located outside the graphic 103, so the first type of scattering bar 102 is a positive scattering bar. Figure 3A The left side of the map shows map 101 separately. Figure 3A On the right side, based on layout 101, an exposure simulation diagram is also provided. It can be seen that after exposure, pattern 103 will form exposure pattern 104. Under normal circumstances, the first type of scattering strip 102 will not form an exposure pattern after exposure, but in hot spot areas, a corresponding exposure pattern 104a will also be formed. Exposure pattern 104a is the imaging, i.e., printing, of the first type of scattering strip 102.

[0061] like Figure 3B The image shows the method for adding scattering bars in OPC correction according to an embodiment of the present invention. Figure 3A The first type of pattern shown is followed by a second type of scattering bar and an exposure simulation diagram. It can be seen that there are adjacent patterns 103 on both sides of the first type of scattering bar 102 that will produce an image. Figure 3B In this configuration, a second type of scattering strip 102a is provided on each of the two sides of the pattern 103. The second type of scattering strip 102a is a negative scattering strip and is located inside the pattern 103. Figure 3B The right side also shows the corresponding exposure simulation diagram, and Figure 3A By comparison, it can be seen that Figure 3BThe image 104a is not exposed, meaning that the imaging of the first type of scattering stripe 102 is eliminated by adding the second type of scattering stripe 102a. However, the size of the image 103 remains unchanged.

[0062] like Figure 4A This is the layout and exposure simulation diagram corresponding to the second type of graphic in the OPC correction method of the present invention embodiment; the layout 201 has graphic 203 and the added first type of scattering bar 202. It can be seen that the first type of scattering bar 202 is located outside the graphic 203, so the first type of scattering bar 202 is a positive scattering bar. Figure 3A The left side of the map shows map 201 separately. Figure 3A On the right side, based on layout 201, an exposure simulation diagram is also provided. It can be seen that pattern 203 will form exposure pattern 204 after exposure. Under normal circumstances, the first type of scattering strip 202 will not form an exposure pattern after exposure, but in hot spot areas, a corresponding exposure pattern 204a will also be formed.

[0063] like Figure 4B The image shows the method for adding scattering bars in OPC correction according to an embodiment of the present invention. Figure 4A The layout and exposure simulation diagram corresponding to the first type of graphic after adding the second type of scattering strips according to the first size condition;

[0064] Figure 4B In the image, the second type of scattering bar 202a is a negative scattering bar and is located inside the larger area of ​​the pattern 203 located to the right of the first type of scattering bar 202. Figure 4B In the second type of scattering strip 202a, it was not set according to the second limiting condition. Figure 4B The right side also shows the corresponding exposure simulation diagram, and Figure 4A By comparison, it can be seen that Figure 4B The exposure pattern 204a is still present, but the area of ​​the exposure pattern 204a has become smaller.

[0065] like Figure 4C The image shows the method for adding scattering bars in OPC correction according to an embodiment of the present invention. Figure 4A The layout and exposure simulation diagram shown are obtained by adding a second type of scattering bar to the first graphic under the second size condition; and Figure 4B compared to, Figure 4C In the middle, the second type of scattering strip 202a is directed toward the side of the first type of scattering strip 202, that is... Figure 4C The left side of the scattering bar 202a is shifted by 10 nm, reducing the spacing between the second type of scattering bar 202a and the first type of scattering bar 202 by 10 nm. Figure 4CAs can be seen from the exposure simulation image on the right side of the image, corresponding to exposure pattern 204a, Figure 4C The exposure pattern 204a is higher than Figure 4B The area of ​​the exposure pattern 204a in the image was reduced, but not completely eliminated.

[0066] like Figure 4D The image shows the method for adding scattering bars in OPC correction according to an embodiment of the present invention. Figure 4A The first graphic shown is followed by the corresponding layout and exposure simulation diagram after adding the second type of scattering strips under the third size condition; and Figure 4B compared to, Figure 4D In the middle, the second type of scattering strip 202a is directed toward the side of the first type of scattering strip 202, that is... Figure 4D The left side is shifted by 20 nm, reducing the spacing between the second type of scattering strip 202a and the first type of scattering strip 202 by 20 nm. Figure 4D As can be seen from the exposure simulation image on the right side of the image, corresponding to exposure pattern 204a, Figure 4D The exposure pattern 204a was eliminated.

[0067] The present invention has been described in detail above through specific embodiments, but these are not intended to limit the invention. Many modifications and improvements can be made by those skilled in the art without departing from the principles of the invention, and these should also be considered within the scope of protection of the present invention.

Claims

1. A method for adding scattering bars in OPC correction, characterized in that, Includes the following steps: Step 1: Add the first type of scattering bar to the layout; Step 2: Select the hotspot region in the plot that will produce an image of the first type of scattering stripe; Step 3: In the hot spot area, a second type of scattering bar is set on the other side of the adjacent pattern boundary corresponding to the first type of scattering bar. The second type of scattering bar is the opposite of the first type of scattering bar. The imaging of the first type of scattering bar is eliminated by adjusting the width of the second type of scattering bar and the distance between it and the adjacent pattern boundary. The first type of scattering bar is a positive scattering bar, and the second type of scattering bar is a negative scattering bar. The positive scattering bar is used to be added to the outside of the graphic, and the negative scattering bar is used to be added to the inside of the graphic. Alternatively, the first type of scattering bar is a negative scattering bar, and the second type of scattering bar is a positive scattering bar.

2. The method for adding scattering stripes in OPC correction as described in claim 1, characterized in that: Before step one, it also includes: During OPC modeling, the first limiting condition for the size of the first type of scattering stripe and the second limiting condition for the size of the second type of scattering stripe are obtained by collecting wafer data of the scattering stripe.

3. The method for adding scattering stripes in OPC correction as described in claim 2, characterized in that: In step two, the size of the first type of scattering stripe in the hotspot region is determined under the first limiting condition.

4. The method for adding scattering bars in OPC correction as described in claim 3, characterized in that: When modeling the OPC, the first limiting condition for the size of the first type of scattering stripe includes: The width of the first type of scattering strip is 1 to 2 times the limit of photomask fabrication; The distance between the first type of scattering strip and the boundary of the adjacent pattern is 1 to 3 times the limit value of the photomask fabrication.

5. The method for adding scattering stripes in OPC correction as described in claim 4, characterized in that: In step two, the first limiting condition for the size of the first type of scattering stripe in the hotspot region includes: The width of the first type of scattering strip is 1 to 1.5 times the limit of photomask fabrication.

6. The method for adding scattering stripes in OPC correction as described in claim 5, characterized in that: In the hotspot region, the size of the first type of scattering strip cannot be reduced under a first limiting condition, including: Reducing the size of the first type of scattering stripe will eliminate the imaging of the first type of scattering stripe, but at the same time it will reduce the depth of focus to a level that does not meet the requirements; Alternatively, the reduction of the first type of scattering stripe cannot eliminate the imaging of the first type of scattering stripe.

7. The method for adding scattering stripes in OPC correction as described in claim 2, characterized in that: In step three, the size of the second type of scattering strip is set according to the second limiting condition, including: The width of the second type of scattering strip is 1 to 2 times the limit of photomask fabrication; The distance between the second type of scattering strip and the boundary of the adjacent pattern is 1 to 3 times the limit value of the photomask fabrication.

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