Opus correction method

Abstract

The application discloses an OPC correction method, which comprises the following steps: step one, providing a target layer of a layout; step two, forming a MEEF hot spot mark; step three, introducing the MEEF hot spot mark into an MBOPC system; step four, setting a first moving rule of a segmentation line segment under the MEEF hot spot mark in the MBOPC system, and the first moving rule is used for ensuring that the MEEF of a pattern covered by the MEEF hot spot mark meets a required value; and step five, running the MBOPC to obtain a mask layer, and in the process of running the MBOPC, the segmentation line segment of the pattern covered by the MEEF hot spot mark moves according to the first moving rule. The application can reduce the MEEF of the mask as a whole, improve a photolithography process window and a product yield, and also can reduce manpower and computer resources, thereby improving publishing efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to a semiconductor integrated circuit manufacturing method, in particular to an optical proximity correction (OPC) method. BACKGROUND

[0002] Mask Error Enhancement Factor (MEEF) can also be called Mask Error Factor, which is defined as the partial derivative of the exposed line width on the wafer to the mask plate line width. After model-based OPC (MBOPC), even the same target pattern, different mask layer simulations will be on target, but some of the mask layer fragments will be closer to the fragments on the opposite polygon due to the more aggressive movement, according to the Rayleigh criterion, the light intensity of the two polygons is superimposed at the distance, the light intensity contrast at the smaller distance is poor, that is, the hot spot caused by aggressive MBOPC leads to large MEEF. If the layout with large MEEF is made into a mask plate, the mask shop cannot make an ideal mask plate without any mask plate width deviation, and after using the mask plate through the lithography process, the photoresist width on the wafer will deviate from the target width, resulting in a smaller process window, even some defects and short or broken lines after copper filling, ultimately affecting the yield of the product.

[0003] The general solution to the OPC process with large MEEF is to check the OPC verify, find the hot spot exceeding the set MEEF threshold, then increase the distance between the two polygons in the retargeting stage, and after changing the retargeting rule, the entire OPC process is run again on the full chip, which not only wastes a lot of engineers' efforts, but also wastes a lot of CPU computing resources, and delays the tape out schedule.

[0004] As shown in FIG. 1, it is a flowchart of the existing OPC correction method for solving large MEEF; including the following steps: Figure 1

[0005] Step S101, the OPC verify checks the MEEF hot spot.

[0006] ​Step S102, Retarget enlarges the hot spot space. The MEEF hot spot is eliminated by enlarging the hot spot space.

[0007] Step S103, Full chip re-runs rule-based & model-based OPC, rule-based OPC represents rule-based OPC, and step S103 is to perform full chip rule-based OPC and model-based OPC.

[0008] Step S104, OPC verify inspection.

[0009] If the inspection result is normal, i.e. OK, the subsequent step S105 is performed. If the inspection result is not as required, i.e. NO, the steps are re-circulated from step S101.

[0010] Step S105, publishing.

[0011] The above existing method is very passive to meet the problem, solve the problem, and can only solve the known problem and waste the time of engineers; in addition, when the existing method modifies the MEEF that is too large, the entire flow needs to be re-run, which wastes CPU resources. SUMMARY

[0012] The technical problem to be solved by the present application is to provide an OPC correction method, which can reduce the MEEF of the mask, improve the lithography process window and product yield, and also reduce manpower and computer resources, thereby improving the publishing progress.

[0013] To solve the above technical problem, the OPC correction method provided by the present application comprises the following steps:

[0014] Step one, providing a target layer of a layout.

[0015] Step two, forming a MEEF hot spot marker, the area covered by the MEEF hot spot marker includes a MEEF hot spot area.

[0016] Step three, introducing the MEEF hot spot marker into the MBOPC system.

[0017] Step four, setting a first movement rule of the segmentation line segment under the MEEF hot spot marker in the MBOPC system, the first movement rule is used to ensure that the MEEF of the pattern in the area covered by the MEEF hot spot marker meets the required value.

[0018] Step five, running the MBOPC to obtain a mask layer, and in the process of running the MBOPC, the segmentation line segment of the pattern in the area covered by the MEEF hot spot marker moves according to the first movement rule.

[0019] Further improvement is, the method further comprises the step of:

[0020] Step six, OPC verification is performed on the mask layer.

[0021] If the OPC verification result meets the requirement, the mask layer is published.

[0022] If the OPC verification result does not meet the requirement, steps one to five are repeated once.

[0023] Further improvement is, the target layer is directly composed of the input original layout.

[0024] Further improvement is, the target layer is obtained by performing rule-based OPC on the input original layout.

[0025] Further improvement is, a second moving rule is set in the MBOPC system, and in the process of running the MBOPC, the split line segment of the pattern outside the area covered by the MEEF hot spot marker is moved according to the second moving rule.

[0026] Further improvement is, in step two, the MEEF hot spot area is an area where the MEEF is greater than the required value when the split line segment of the pattern is moved according to the second moving rule.

[0027] Further improvement is, the first moving rule includes setting the difference between the moving amount of the split line segment and the moving amount of the adjacent split line segment.

[0028] Further improvement is, the moving amount is the distance between the split line segment and the target line segment set in the target layer.

[0029] Further improvement is, under the condition that the photoresist profile of the pattern after MBOPC meets the target value, the smaller the difference between the moving amount of the adjacent split line segment is, the better.

[0030] Further improvement is, in step two, the area covered by the MEEF hot spot marker is selected according to the feature of the pattern structure in the target layer covered by the MEEF hot spot marker.

[0031] Further improvement is, the area covered by the MEEF hot spot marker further includes the modeling pattern structure area with optical contrast that does not meet the requirement.

[0032] Further improvement is that in step two, according to the pattern structure or optical contrast of the MEFE hot spot area not meeting the requirements of the pattern structure for modeling in the target layer, a target edge is selected, the target edge is expanded to form a box structure, and the box structure is used as the MEEF hot spot mark.

[0033] Further improvement is that the pattern structure or optical contrast of the MEFE hot spot area not meeting the requirements of the pattern structure for modeling in the target layer includes line width, pitch, length and angle, and the target edge is selected by setting limits of the line width, the pitch, the length and the angle.

[0034] The present application provides a target layer, and instead of directly performing MBOPC, MEEF hot spot marks are formed in selected areas including MEEF hot spot areas in advance, a first movement rule is specially set for the areas covered by the MEEF hot spot marks, and in the MBOPC process, the segments of the patterns in the areas covered by the MEEF hot spot marks are moved according to the first movement rule. Since the first movement rule is specially set to avoid excessive MEEF of the MEEF hot spot areas, the MEEF of the areas covered by the MEEF hot spot marks is reduced. Finally, the present application can reduce the overall MEEF of the mask and improve the lithography process window and product yield.

[0035] Since the present application only needs to set a first movement rule for the areas covered by the MEEF hot spot marks to reduce the overall MEEF of the mask, the movement of the segments of the patterns outside the areas covered by the MEEF hot spot marks is not affected, so the patterns in the areas covered by the MEEF hot spot marks can be adjusted while avoiding the simulation results of the patterns outside the areas covered by the MEEF hot spot marks after correction from not meeting the target values.

[0036] The present application can preprocess the areas where MEEF hot spots may occur before MBOPC by setting MEEF hot spot marks and a first movement rule, and the MEEF hot spots are reduced after MBOPC. Therefore, the time required for engineers to check hot spots is reduced, and the time required for running OPC again due to modification of scripts is saved, so that human resources and computer resources are reduced, and the publishing efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0037] The present application will be further described in detail below in combination with the drawings and specific embodiments:

[0038] Figure 1 is a flowchart of the existing OPC correction method;

[0039] Figure 2 is a flowchart of the OPC correction method of the embodiment of the present application;

[0040] Figure 3 is a schematic diagram of MEEF hot spot marking in the OPC correction method of the embodiment of the present application;

[0041] Figure 4 is MEEF of the mask obtained by the prior OPC correction method;

[0042] Figure 5 is MEEF of the mask obtained by the OPC correction method of the embodiment of the present application. DETAILED DESCRIPTION

[0043] As shown in Figure 2 , it is a flow chart of the OPC correction method of the embodiment of the present application; as shown in Figure 3 , it is a schematic diagram of MEEF hot spot marking 103 in the OPC correction method of the embodiment of the present application; the OPC correction method of the embodiment of the present application comprises the following steps:

[0044] Step one, providing a target layer 101 of a layout.

[0045] In some embodiments, the target layer 101 is obtained by rule-based OPC on the input original layout. This step one corresponds to step S201 in Figure 2 , that is, importing a layout and performing rule-based OPC.

[0046] In other embodiments, the target layer 101 can also be directly composed of the input original layout.

[0047] Figure 3 In , only three patterns of the target layer 101 are shown.

[0048] Step two, forming a MEEF hot spot marking 103, the area covered by the MEEF hot spot marking 103 including a MEEF hot spot area.

[0049] In the embodiment of the present application, the MEEF hot spot area is an area in which MEEF is greater than the required value when a split line segment of a pattern is moved according to a subsequent second moving rule in the process of running the MBOPC. The second moving rule is the moving rule corresponding to the prior method.

[0050] The area covered by the MEEF hot spot marking 103 is selected according to the characteristics of the pattern structure in the target layer 101 covered by the MEEF hot spot marking 103.

[0051] In some embodiments, the area covered by the MEEF hot spot marking 103 also includes a pattern structure for modeling whose optical contrast does not meet the requirements.

[0052] According to the feature of the pattern structure or the optical contrast of the MEFE hot spot area not meeting the requirement, a target edge is selected in the pattern structure in the target layer 101, the target edge is extended to form a box structure, and the box structure is used as the MEEF hot spot mark 103.

[0053] The feature of the pattern structure or the optical contrast of the MEFE hot spot area not meeting the requirement includes line width, pitch, length and angle, and the target edge is selected by setting the limit of the line width, the pitch, the length and the angle. That is, by limiting the selection of the features of the line width, the pitch, the length and the angle, the area covered by the MEEF hot spot mark 103 can be automatically obtained, and thus the MEEF hot spot mark 103 is set in the selected area.

[0054] Step three, the MEEF hot spot mark 103 is introduced into the MBOPC system.

[0055] Step four, a first movement rule of the segmentation line segment under the MEEF hot spot mark 103 is set in the MBOPC system, and the first movement rule is used to ensure that the MEEF of the pattern in the area covered by the MEEF hot spot mark 103 meets the required value.

[0056] Steps two, three and four correspond to step S202 in Figure 2 , that is, the MEEF marker is added, and the movement rule is set.

[0057] In the embodiment of the application, a second movement rule is set in the MBOPC system, and in the subsequent operation of the MBOPC, the segmentation line segment of the pattern outside the area covered by the MEEF hot spot mark 103 moves according to the second movement rule. The second movement rule is a rule originally possessed by the MBOPC system, and if the first movement rule is not set, the segmentation line segment of all patterns on the layout will move according to the second movement rule in the MBOPC.

[0058] In the embodiment of the application, the first movement rule includes setting the movement amount of the segmentation line segment and the difference between the movement amounts of adjacent segmentation line segments.

[0059] The movement amount is the distance between the segmentation line segment and the target line segment set in the target layer 101.

[0060] Under the condition that the photoresist profile of the pattern after the MBOPC meets the target value, the smaller the difference between the movement amounts of adjacent segmentation line segments is, the better. Figure 3The mask layer 102 in the figure shows two adjacent segments of the cutting line with dashed lines, and d1 represents the difference of the moving amount of the adjacent segments of the cutting line. In the embodiment of the present application, the first moving rule limits d1 to avoid aggressive movement and prevent the situation of too large MEEF.

[0061] The moving amount of the segment of the cutting line has positive and negative, and the moving amount of the segment of the cutting line in the target layer is negative, and vice versa.

[0062] Step five, running the MBOPC to obtain the mask layer 102, and in the process of running the MBOPC, the segment of the cutting line of the pattern in the area covered by the MEEF hot spot mark 103 moves according to the first moving rule. The segment of the cutting line of the pattern outside the area covered by the MEEF hot spot mark 103 moves according to the second moving rule.

[0063] Step five corresponds to step S203 in the figure, that is, running the model-based OPC. Figure 2

[0064] Further comprising the step:

[0065] Step six, performing OPC verification on the mask layer 102. Step six corresponds to step S204 in the figure, that is, OPC verification inspection. Figure 2

[0066] If the OPC verification result meets the requirements, the mask layer 102 is published according to the mask layer 102. That is, step S205 in the figure is performed. Figure 2

[0067] If the OPC verification result does not meet the requirements, steps one to five are repeated once.

[0068] After the target layer 101 is provided, the embodiment of the present application does not directly perform MBOPC, but forms the MEEF hot spot mark 103 in the selected area in advance, the selected area includes the MEEF hot spot area, and then the first moving rule is specially set for the area covered by the MEEF hot spot mark 103. In the process of MBOPC, the segment of the cutting line of the pattern in the area covered by the MEEF hot spot mark 103 moves according to the first moving rule. Since the first moving rule is specially set to avoid too large MEEF of the MEEF hot spot area, the MEEF of the area covered by the MEEF hot spot mark 103 is reduced. Finally, the embodiment of the present application can reduce the MEEF of the whole mask and improve the lithography process window and product yield.

[0069] ​​​Since the embodiment of the present application only needs to set the first movement rule for the area covered by the MEEF hot spot mark 103 to reduce the MEEF of the mask, the movement of the split line segment of the pattern outside the area covered by the MEEF hot spot mark 103 will not be affected, so the pattern in the area covered by the MEEF hot spot mark can be adjusted while avoiding the simulation result of the pattern outside the area covered by the MEEF hot spot mark 103 after correction from not meeting the target value.

[0070] The embodiment of the present application can preprocess the area where the MEEF hot spot may appear before the MBOPC by setting the MEEF hot spot mark 103 and the first movement rule, and the MEEF hot spot will be reduced after the MBOPC, so not only the time required by the engineer to check the hot spot can be reduced, but also the time required to run the OPC again due to the modification of the script can be saved, thereby reducing the manpower and computer resources, and improving the publishing efficiency.

[0071] As shown in FIG. 1, Figure 4 is the MEEF of the mask obtained by the prior OPC correction method; the target layer is indicated by a mark 101a alone, the mask layer is indicated by a mark 102a alone, and the MEEF is indicated by a mark 201a.

[0072] As shown in FIG. 2, Figure 5 is the MEEF of the mask obtained by the OPC correction method of the embodiment of the present application; the target layer is indicated by a mark 101b alone, the mask layer is indicated by a mark 102b alone, and the MEEF is indicated by a mark 201b.

[0073] Comparing Figure 4 and Figure 5 , it can be seen that the embodiment of the present application can reduce the MEEF from 7.0 of Figure 4 to 6.2 of Figure 5 , with a reduction of about 10%.

[0074] The above has described the present application in detail through specific embodiments, but these do not constitute a limitation on the present application. Those skilled in the art can also make many modifications and improvements without departing from the principle of the present application, and these should also be considered as the protection scope of the present application.

Claims

1. An OPC correction method characterized by, The method comprises the following steps: Step one, providing a target layer of a layout; Step two, forming a MEEF hotspot mark, the area covered by the MEEF hotspot mark comprising a MEEF hotspot area; Step three, importing the MEEF hotspot mark into an MBOPC system; Step four, setting a first movement rule of a segmentation line segment under the MEEF hotspot mark in the MBOPC system, the first movement rule being used to ensure that the MEEF of the pattern in the area covered by the MEEF hotspot mark meets a required value; Step five, running the MBOPC to obtain a mask layer, during the running of the MBOPC, the segmentation line segment of the pattern in the area covered by the MEEF hotspot mark moving according to the first movement rule.

2. The OPC correction method of claim 1, wherein The method further comprises the following steps: Step six, performing OPC verification on the mask layer; If the OPC verification result meets the requirement, publishing according to the mask layer; If the OPC verification result does not meet the requirement, repeating steps one to five once.

3. The OPC correction method of claim 1, wherein: The target layer is directly composed of an input original layout.

4. The OPC correction method of claim 1, wherein: The target layer is obtained by performing rule-based OPC on an input original layout.

5. The OPC correction method of claim 1, wherein: A second movement rule is set in the MBOPC system, during the running of the MBOPC, the segmentation line segment of the pattern outside the area covered by the MEEF hotspot mark moving according to the second movement rule.

6. The OPC correction method of claim 5, wherein: In step two, the MEEF hotspot area is an area in which the MEEF is greater than the required value when the segmentation line segment moves according to the second movement rule.

7. The OPC correction method of claim 5, wherein: The first movement rule comprises setting the movement amount of the segmentation line segment and the difference between the movement amounts of adjacent segmentation line segments.

8. The OPC correction method of claim 7, wherein: The movement amount is the distance between the segmentation line segment and a target line segment set in the target layer.

9. The OPC correction method of claim 7, wherein: Under the condition that the photoresist profile of the pattern after MBOPC meets the target value, the smaller the difference between the movement amounts of adjacent segmentation line segments is, the better.

10. The OPC correction method according to claim 1 or 6, wherein: In step two, the area covered by the MEEF hotspot mark is selected according to the features of the pattern structure of the MEEF hotspot mark in the target layer.

11. The OPC correction method of claim 10, wherein: The area covered by the MEEF hotspot mark further comprises a pattern structure area for modeling with which the optical contrast does not meet the requirement.

12. The OPC correction method of claim 11, wherein: In step two, a target edge is selected according to the pattern structure of the MEEF hotspot area or the features of the pattern structure for modeling with which the optical contrast does not meet the requirement in the target layer, the target edge is expanded to form a box structure, and the box structure is used as the MEEF hotspot mark.

13. The OPC correction method of claim 12, wherein: The features of the pattern structure of the MEEF hotspot area or the pattern structure for modeling with which the optical contrast does not meet the requirement in the target layer comprise line width, pitch, length and angle, and the target edge is selected by setting limits on the line width, the pitch, the length and the angle.

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