OPC method

Abstract

The present invention provides an OPC method, including: defining characteristic variables of a target pattern of the convex pattern: convex height, convex width, and adjacent sides; setting characteristic conditions and correction evaluation rules of the convex pattern; obtaining an influencing factor of the convex height; applying the influencing factor of the convex height to the convex height for OPC correction; obtaining an intersection point between a simulated pattern of the convex pattern and the target pattern of the convex pattern on the convex height; determining whether the intersection point conforms to the correction evaluation rule, and if so, completing the OPC correction. By obtaining the influencing factor of the convex height, using the influencing factor of the convex height to perform OPC processing on the convex pattern, and then evaluating whether the intersection point conforms to the correction evaluation rule, the present application can reduce the number of OPC corrections, avoid error reporting during the OPC correction process, improve the coverage rate of the convex pattern for the internal via layer, save the OPC correction time, and improve the OPC correction efficiency.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and particularly relates to an OPC method. Background Art

[0002] In the process of deep sub-micron semiconductor manufacturing, the connection between the metal layer and the via layer plays a crucial role in device performance. If the coverage rate of the metal layer and the via layer does not meet the standard, it will lead to poor conduction performance or even failure between different metal layers, ultimately reducing the product yield.

[0003] As the technology node continues to decrease, OPC (Optical Proximity Correction) is a necessary key technology to improve the pattern resolution and increase the process window of the development process. The convex pattern of the metal layer is affected by the rounding effect, which will reduce its coverage rate of the via layer pattern set in the convex area of the convex pattern of the metal layer. Conventional OPC correction methods have a recommended number of iterations according to the platform technology and the complexity of OPC. Perform OPC correction according to the number of iterations, and then check the result after OPC. If an error is reported and there is a process risk, continue to optimize OPC to solve the error; if an error is reported and there is no process risk, directly confirm that the OPC correction is completed. Even if the target value is not reached 100%, but because there is no process risk, the process after OPC can be carried out. However, this limitation on the number of OPC corrections will inevitably encounter various errors during the OPC process, and it is impossible to quickly and effectively improve the coverage rate of the convex pattern to the internal via layer, thus greatly increasing the OPC processing time. Summary of the Invention

[0004] This application provides an OPC method, which can solve at least one of the problems such as the limited number of OPC corrections, errors during the OPC process, low coverage rate of the convex pattern to the internal via layer, too long OPC correction time, and too low OPC correction efficiency.

[0005] On the one hand, an embodiment of this application provides an OPC method. The patterns participating in the OPC correction include: convex patterns, wherein a via pattern is set in the convex area of the convex pattern; the OPC method includes:

[0006] The first step: Define the characteristic variables of the target pattern of the convex pattern; wherein, the characteristic variables of the target pattern of the convex pattern include: convex height, convex width, and adjacent edge;

[0007] The second step: Set the characteristic conditions of the convex pattern according to the characteristic variables of the target pattern of the convex pattern, and set the correction evaluation rules;

[0008] Third step: Move the convex height by a certain step length to obtain the influence factor of the convex height;

[0009] Fourth step: Apply the influence factor of the convex height to the convex height and perform OPC processing;

[0010] Fifth step: Obtain the simulated graph of the convex-shaped graph and obtain the intersection point of the simulated graph of the convex-shaped graph and the target graph of the convex-shaped graph on the convex height;

[0011] Sixth step: Determine whether the intersection point conforms to the correction evaluation rule. If the intersection point conforms to the correction evaluation rule, complete the OPC correction; if the intersection point does not conform to the correction evaluation rule, return to execute the third step.

[0012] Optionally, in the OPC method, the characteristic conditions of the convex-shaped graph are set as:

[0013] N 1 ×D w ≤(T w , T h )≤N 2 ×D w ;

[0014] T L ≥N 3 ×D w ;

[0015] Among them, D w is the minimum design size of the convex-shaped graph; T h is the convex height; T w is the convex width, T L is the adjacent side; 0.5≤N 1 ≤1.5; 1.0≤N 2 ≤2.5; N 3 ≥2.

[0016] Optionally, in the OPC method, the correction evaluation rule is set as: The intersection point of the simulated graph of the convex-shaped graph and the target graph of the convex-shaped graph on the convex height is located in the interval from 1 / 2 height to 3 / 4 height of the convex height.

[0017] Optionally, in the OPC method, the sixth step includes: Determine whether the intersection point is located in the interval from 1 / 2 height to 3 / 4 height of the convex height. If the intersection point is located in the interval from 1 / 2 height to 3 / 4 height of the convex height, complete the OPC correction; if the intersection point is not located in the interval from 1 / 2 height to 3 / 4 height of the convex height, return to execute the third step.

[0018] Optionally, in the OPC method described above, the third step includes:

[0019] Moving the convex height at least three times with a step size of 5 nm without moving the convex width;

[0020] Obtaining the influence factor of the convex height according to the weight value in each movement, the movement amount of the convex height in each movement, and the edge placement error of the convex width in each movement.

[0021] Optionally, in the OPC method described above, the calculation formula for the influence factor of the convex height is:

[0022]

[0023] where k is the influence factor of the convex height; W i is the weight value in each movement, M Thi is the movement amount of the convex height in each movement; EPE Twi is the edge placement error of the convex width in each movement.

[0024] Optionally, in the OPC method described above, the third step further includes:

[0025] Obtaining the difference in the edge placement error of the convex width according to the edge placement error of the convex width in the previous movement and the edge placement error of the convex width in the current movement;

[0026] Obtaining the correction situation of the convex pattern in the current movement according to the difference in the edge placement error of the convex width.

[0027] Optionally, in the OPC method described above, the fourth step includes:

[0028] In each iteration, obtaining the movement amount of the convex width according to the edge placement error of the convex width;

[0029] Performing OPC correction on the convex width according to the movement amount of the convex width;

[0030] In each iteration, obtaining the movement amount of the convex height according to the influence factor of the convex height, the edge placement error of the convex width, and the edge placement error of the convex height;

[0031] Performing OPC correction on the convex height according to the movement amount of the convex height.

[0032] Optionally, in the OPC method described above, the calculation formula for the movement amount of the convex width is:

[0033]

[0034] where MTwj is the movement amount of the convex width in each iteration; feedback is the attenuation coefficient; EPE Twj is the edge placement error of the current convex width.

[0035] Optionally, in the OPC method described above, the formula for calculating the movement amount of the convex height is:

[0036]

[0037] where M Thj is the movement amount of the convex height in each iteration; k is the influence factor of the convex height; feedback is the attenuation coefficient; EPE Twj is the edge placement error of the current convex width; EPE Thj is the edge placement error of the current convex height.

[0038] The technical solution of this application has at least the following advantages:

[0039] This application obtains the influence factor of the convex height, applies the influence factor of the convex height to the convex height for OPC processing, and then uses a pre-set correction evaluation rule to evaluate whether the intersection of the simulated graph of the convex graph after OPC correction and the target graph of the convex graph on the convex height conforms to the correction evaluation rule. In this way, while reducing the number of OPC corrections, it can avoid errors during the OPC processing, improve the coverage rate of the convex graph for the internal via layer, save the OPC correction time, and improve the OPC correction efficiency. Description of the Drawings

[0040] In order to more clearly illustrate the specific embodiments of this application or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0041] Figure 1 is a schematic diagram of the target graph of the convex graph in the embodiment of the present invention;

[0042] Figure 2 is a flowchart of the OPC method in the embodiment of the present invention;

[0043] Figure 3 is a schematic diagram of the convex graph after OPC correction in the embodiment of the present invention;

[0044] Among them, the reference numerals are explained as follows:

[0045] 11 - Convex - type figure, 12 - Through - hole figure, 13 - Contour line of the target figure of the convex - type figure after OPC correction, 14 - Contour line of the simulated figure of the convex - type figure. Detailed implementation mode

[0046] Next, the technical solutions in the present application will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope protected by the present application.

[0047] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0048] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can also be the communication inside two elements. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0049] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0050] The inventor found that after OPC correction according to a predetermined number of times, the EPE (Edge Placement Error) in the raised area of the convex - type figure is relatively large, resulting in that at the position of the raised area, the coverage rate of the convex - type figure for the through - hole figure can only reach 70% at most.

[0051] Based on this, the embodiment of the present application provides an OPC method. Refer to Figure 1 , Figure 1 is a schematic diagram of the target figure of the convex - type figure in the embodiment of the present invention. The figures participating in OPC correction include: a convex - type figure 11, wherein a through - hole figure 12 is arranged in the raised area of the convex - type figure 11. Figure 1The convex graphic 11 therein is the target graphic.

[0052] Reference Figure 2 , Figure 2 is the flowchart of the OPC method of the embodiment of the present invention.

[0053] Specifically, the OPC method includes:

[0054] The first step S1: Define the characteristic variables of the target graphic of the convex graphic 11; wherein, the characteristic variables of the target graphic of the convex graphic 11 include: convex height T h , convex width T w and adjacent side T L .

[0055] It should be noted that the inventor found that the main reason for the current maximum coverage rate of the convex graphic for the via graphic can only reach 70% is that the EPE of the convex height T h is relatively large, resulting in the convex width T w which should originally maintain a certain distance from the via graphic 12 actually being located in the via graphic 12 when transferred to the photoresist.

[0056] The second step S2: Set the characteristic conditions of the convex graphic 11 according to the characteristic variables of the target graphic of the convex graphic 11, and set the correction evaluation rule.

[0057] In this embodiment, the characteristic conditions of the convex graphic can be set as:

[0058] N 1 ×D w ≤(T w , T h )≤N 2 ×D w ;

[0059] T L ≥N 3 ×D w ;

[0060] wherein, D w is the minimum design size of the convex graphic; T h is the convex height; T w is the convex width, T L is the adjacent side; 0.5≤N 1 ≤1.5; 1.0≤N 2 ≤2.5; N 3 ≥2.

[0061] In this embodiment, the minimum design size D w of the convex graphic can be selected as 0.16; N 1It can be selected as 0.5; N 2 It can be selected as 1.5; N 3 It can be selected as 2.5.

[0062] Furthermore, the correction evaluation rule can be set as: the intersection point P of the simulated graph of the convex graph and the target graph of the convex graph on the convex height is located in the interval from 1 / 2 height to 3 / 4 height of the convex height.

[0063] The third step S3: Move the convex height at a certain step length to obtain the influence factor of the convex height. Specifically, the third step may include:

[0064] S3.1: Move the convex height at least three times with a step length of 5 nm while not moving the convex width;

[0065] S3.2: Obtain the influence factor of the convex height according to the weight value in each movement, the movement amount of the convex height in each movement, and the edge placement error of the convex width in each movement.

[0066] Preferably, the calculation formula for the influence factor of the convex height is:

[0067]

[0068] where k is the influence factor of the convex height; W i is the weight value in each movement, M Thi is the movement amount of the convex height in each movement; EPE Twi is the edge placement error of the convex width in each movement. In this embodiment, i takes the value of 3.

[0069] Referring to Table 1, Table 1 is the OPC operation result of three - time movement in the third step of the embodiment of the present invention. In this embodiment, the weight value can be set by the user according to the actual situation. The weight value selected in the first movement is 50, the weight value selected in the second movement is 30, and the weight value selected in the third movement is 20. The EPE of the convex height in the first movement is - 46, the EPE of the convex height in the second movement is - 40.5, and the EPE of the convex height in the third movement is - 36.

[0070] Table 1

[0071] Step Movement EPE ΔEPE Weight value S0 / -54 / / S1 5 -46 8 50 S2 10 -40.5 5.5 30 S3 15 -36 3.5 20

[0072] Preferably, the third step may further include: S3.11: Obtain the difference ΔEPE of the edge placement error of the convex width according to the edge placement error EPE of the convex width in the previous movement and the edge placement error EPE of the convex width in the current movement; S3.12: Obtain the correction situation of the convex-shaped figure in the current movement according to the difference of the edge placement error of the convex width. The ΔEPE of the convex height in the first movement is 8, the ΔEPE of the convex height in the second movement is 5.5, and the ΔEPE of the convex height in the third movement is 3.5. It can be seen that with each movement, the ΔEPE of the convex height gradually decreases.

[0073] Fourth step S4: Apply the influence factor k of the convex height to the convex height for OPC processing.

[0074] Specifically, the fourth step may include:

[0075] S4.1: In each iteration, obtain the movement amount of the convex width according to the edge placement error of the convex width;

[0076] S4.2: Perform OPC correction on the convex width according to the movement amount of the convex width;

[0077] S4.3: In each iteration, obtain the movement amount of the convex height according to the influence factor of the convex height, the edge placement error of the convex width, and the edge placement error of the convex height;

[0078] S4.4: Perform OPC correction on the convex height according to the movement amount of the convex height.

[0079] In this embodiment, the calculation formula for the movement amount of the convex width is:

[0080]

[0081] where M Twj is the movement amount of the convex width in each iteration; feedback is the attenuation coefficient; EPE Twj is the current edge placement error of the convex width.

[0082] In this embodiment, the calculation formula for the movement amount of the convex height is:

[0083]

[0084] where M Thj is the movement amount of the convex height in each iteration; k is the influence factor of the convex height; feedback is the attenuation coefficient, where feedback can be a fixed value, which can be provided before performing OPC, or can be adjusted during the OPC loop according to the actual OPC situation; EPE Twjis the edge placement error of the current convex width; EPE Thj is the edge placement error of the current convex height; j is the number of loop iterations, which can be set according to the actual situation.

[0085] Reference Figure 3 , Figure 3 is a schematic diagram of the convex-shaped pattern after the OPC correction is completed in the embodiment of the present invention. As can be seen from Figure 3 , since both the convex height and the convex width have been corrected by OPC, the contour line 13 of the target pattern of the convex-shaped pattern after OPC correction is slightly higher than the original contour line of the target pattern of the convex-shaped pattern.

[0086] The fifth step S5: Obtain the simulated pattern of the convex-shaped pattern, and obtain the intersection points of the simulated pattern of the convex-shaped pattern and the target pattern of the convex-shaped pattern on the convex height. Specifically, as shown in Figure 3 , there is an intersection point P on each side of the convex height between the contour line 13 of the target pattern of the convex-shaped pattern after OPC correction and the contour line 14 of the simulated pattern of the convex-shaped pattern.

[0087] The sixth step S6: Determine whether these two intersection points P meet the correction evaluation rule. If the intersection points meet the correction evaluation rule, the OPC correction is completed; if the intersection points do not meet the correction evaluation rule, return to execute the third step S3.

[0088] Specifically, the sixth step may include:

[0089] S6: Determine whether the two intersection points P on the left and right of the convex height between the contour line 13 of the target pattern of the convex-shaped pattern after OPC correction and the contour line 14 of the simulated pattern of the convex-shaped pattern are located in the interval T of 1 / 2 height to 3 / 4 height of the convex height evaluate . If the intersection point P is located in the interval of 1 / 2 height to 3 / 4 height of the convex height, the OPC correction is completed; if the intersection point P is not in the interval of 1 / 2 height to 3 / 4 height of the convex height, return to execute the third step to continue the OPC correction. As can be seen from Figure 3 , the contour line 14 of the simulated pattern of the convex-shaped pattern is the convex-shaped pattern actually transferred to the photoresist, and it can be seen that the coverage rate of the convex-shaped pattern for the through-hole pattern reaches 100%.

[0090] In this application, the influence factor k of the convex height is obtained, and the influence factor k of the convex height is applied to the convex height for OPC processing. Then, the pre-set correction evaluation rule is used to evaluate whether the intersection point P of the simulated graph of the convex graph after OPC correction and the target graph of the convex graph on the convex height conforms to the correction evaluation rule. In this way, while reducing the number of OPC corrections, it is possible to avoid errors during the OPC processing, improve the coverage rate of the convex graph for the internal via layer, save the OPC correction time, and improve the OPC correction efficiency.

[0091] Obviously, the above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present application.

Claims

1. An OPC method, characterized in that, the patterns involved in OPC correction include: convex patterns, wherein a through-hole pattern is arranged in the protruding area of the convex patterns; the OPC method includes: The first step: defining the characteristic variables of the target pattern of the convex pattern; wherein, the characteristic variables of the target pattern of the convex pattern include: convex height, convex width, and adjacent sides; The second step: setting the characteristic conditions of the convex pattern according to the characteristic variables of the target pattern of the convex pattern, and setting the correction evaluation rules; The third step: moving the convex height at a certain step size to obtain the influence factor of the convex height; wherein, the third step further includes: obtaining the difference in the edge placement error of the convex width according to the edge placement error of the convex width in the previous movement and the edge placement error of the convex width in the current movement; obtaining the correction situation of the convex pattern in the current movement according to the difference in the edge placement error of the convex width; The fourth step: applying the influence factor of the convex height to the convex height for OPC processing; wherein, the fourth step includes: in each iteration, obtaining the movement amount of the convex width according to the edge placement error of the convex width; performing OPC correction on the convex width according to the movement amount of the convex width; in each iteration, obtaining the movement amount of the convex height according to the influence factor of the convex height, the edge placement error of the convex width, and the edge placement error of the convex height; performing OPC correction on the convex height according to the movement amount of the convex height; The fifth step: obtaining the simulated pattern of the convex pattern, and obtaining the intersection point of the simulated pattern of the convex pattern and the target pattern of the convex pattern on the convex height; The sixth step: judging whether the intersection point conforms to the correction evaluation rules. If the intersection point conforms to the correction evaluation rules, the OPC correction is completed; if the intersection point does not conform to the correction evaluation rules, return to execute the third step.

2. The OPC method according to claim 1, characterized in that, the characteristic conditions of the convex pattern are set as: N 1 ×D w ≤(T w ,T h )≤N 2 ×D w ; T L ≥N 3 ×D w ; Among them, D w is the minimum design size of the convex-shaped figure; T h is the convex height; T w is the convex width, T L is the adjacent side; 0.5 ≤ N 1 ≤ 1.5; 1.0 ≤ N 2 ≤ 2.5; N 3 ≥ 2.

3. The OPC method according to claim 1, characterized in that, the correction evaluation rules are set as: the intersection point of the simulated pattern of the convex pattern and the target pattern of the convex pattern on the convex height is located in the interval of 1 / 2 height to 3 / 4 height of the convex height.

4. The OPC method according to claim 3, characterized in that, the sixth step includes: judging whether the intersection point is located in the interval of 1 / 2 height to 3 / 4 height of the convex height. If the intersection point is located in the interval of 1 / 2 height to 3 / 4 height of the convex height, the OPC correction is completed; if the intersection point is not located in the interval of 1 / 2 height to 3 / 4 height of the convex height, return to execute the third step.

5. The OPC method according to claim 1, characterized in that, the third step includes: moving the convex height at least three times with a step size of 5 nm without moving the convex width; Obtain the influence factor of the convex height according to the weight value in each movement, the movement amount of the convex height in each movement, and the edge placement error of the convex width in each movement.

6. The OPC method according to claim 5, wherein, the calculation formula for the influence factor of the convex height is: Among them, k is the influence factor of the convex height; W i is the weight value in each movement, M Thi is the movement amount of the convex height in each movement; EPE Twi is the edge placement error of the convex width in each movement.

7. The OPC method according to claim 1, wherein, the calculation formula for the movement amount of the convex width is: where M Twj is the movement amount of the convex width in each iteration; feedback is the attenuation coefficient; EPE Twj is the edge placement error of the current convex width.

8. The OPC method according to claim 1, wherein, the calculation formula for the movement amount of the convex height is: where M Thj is the moving amount of the convex height in each iteration; k is the influence factor of the convex height; feedback is the attenuation coefficient; EPE Twj is the edge placement error of the current convex width; EPE Thj is the edge placement error of the current convex height.

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