Method of improving edge placement error

Abstract

The present application provides a method for improving edge placement error, providing a design layout, and performing first optical proximity correction on the design layout to obtain a first mask pattern; wherein at least one segment pattern is formed on the first mask pattern, so that the first mask pattern is in a stepped shape, and a first edge placement error exists between a first exposure profile of the first mask pattern and the design layout; a compensation pattern is inserted at a position where a height difference exists in the first mask pattern to obtain a second mask pattern; and a second exposure profile is obtained according to the second mask pattern, so that a second edge placement error existing between the second exposure profile and the design layout is smaller than the first edge placement error. In the present application, a stepped pattern is generated as a buffer between two patterns with a large height difference in the mask correction pattern, and the profile generated by exposure has a smaller edge placement error (EPE), and the wave phenomenon on the profile is also weakened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a method for improving edge placement error. BACKGROUND

[0002] In the prior art, when performing optical proximity correction on a pattern, as shown in the following figure, from the pre-processing of the pattern to the target value, width / space reference size table is judged at the edge of the polygon, and only the specified size value is the final target, so that the optical proximity correction (OPC) close to the target pattern can be obtained. Figure 1

[0003] As shown in the following figure, at the place where the two adjacent fragment patterns have a large difference, the exposure profile relative to the corrected mask pattern still has a large edge placement error (EPE), and a wavy phenomenon occurs. Figure 2

[0004] To solve the above problems, a new method for improving edge placement error is needed. SUMMARY

[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a method for improving edge placement error, which is used to solve the problem that in the prior art, at the place where the two adjacent fragment patterns have a large difference, the exposure profile relative to the corrected mask pattern still has a large edge placement error, and a wavy phenomenon occurs.

[0006] To achieve the above-mentioned purpose and other related purposes, the present application provides a method for improving edge placement error, comprising:

[0007] Step one, providing a design layout, and performing first optical proximity correction on the design layout to obtain a first mask pattern; wherein at least one fragment pattern is formed on the first mask pattern, so that the first mask pattern is in a stepped shape, and a first edge placement error exists between the first exposure profile of the first mask pattern and the design layout;

[0008] Step two, inserting a compensation pattern at the place where the height difference exists in the first mask pattern to obtain a second mask pattern;

[0009] Step three, obtaining a second exposure profile according to the second mask pattern, so that a second edge placement error existing between the second exposure profile and the design layout is smaller than the first edge placement error.

[0010] Preferably, the shape of the fragment pattern in step one is a rectangle.

[0011] Preferably, the fragment pattern in step one is one.​​

[0012] Preferably, the number of the segment patterns in step one is two.

[0013] Preferably, the shape of the compensation pattern in step two is rectangular.

[0014] Preferably, the shape of the compensation pattern in step two is step-like, and the height of each step decreases successively from the higher side to the lower side of the first mask pattern.

[0015] Preferably, the compensation pattern in step two shares the same corner with the first mask pattern.

[0016] Preferably, the width X of the compensation pattern in step two is D*P, where D is the width of the segment pattern, and P is greater than 0 and less than 1.

[0017] Preferably, the width X of the rectangular compensation pattern in step two is D*P, where D is the width of the segment pattern, and P is 0.5.

[0018] Preferably, the compensation pattern in step two is composed of n rectangular patterns with successively decreasing heights, and the width of the nth rectangular pattern is X=D*(P^n), where D is the width of the segment pattern, P is greater than 0 and less than 1, and n is a positive integer greater than 2.

[0019] Preferably, the compensation pattern in step two is composed of n rectangular patterns with successively decreasing heights, and the width of the nth rectangular pattern is X=D*(P^n), where D is the width of the segment pattern, P is 0.5, and n is a positive integer greater than 2.

[0020] Preferably, the first exposure profile in step one is wavy, and the distance between the first exposure profile and the design layout is defined as the first edge placement error.

[0021] Preferably, the compensation pattern in step two is located at the concave edge of the first mask pattern, which is the edge of one segment pattern opposite to the other side of the first mask pattern or the edge between two segment patterns.

[0022] Preferably, the second exposure profile in step three is wavy, and the distance between the second exposure profile and the design layout is defined as the second edge placement error.

[0023] Preferably, the above-mentioned method is used for optical proximity correction of rectangular patterns in a logic circuit layout.

[0024] Preferably, the rectangular pattern is a gate pattern.

[0025] As mentioned above, the method for improving edge placement error of the present application has the following advantages:

[0026] The present application generates a stepped pattern as a buffer between two patterns with large height difference in the mask correction pattern, and the profile generated by exposure has a smaller edge placement error (EPE), and the wave phenomenon on the profile is also reduced. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A schematic diagram of optical proximity correction as prior art is shown;

[0028] Figure 2 A schematic diagram of exposure without inserting compensation pattern as the first embodiment of the present application is shown;

[0029] Figure 3 A schematic diagram of exposure with inserting compensation pattern as the first embodiment of the present application is shown;

[0030] Figure 4 A schematic diagram of exposure without inserting compensation pattern as the second embodiment of the present application is shown;

[0031] Figure 5 A schematic diagram of exposure with inserting compensation pattern as the second embodiment of the present application is shown;

[0032] Figure 6 A schematic diagram of exposure without inserting compensation pattern as the third embodiment of the present application is shown;

[0033] Figure 7 A schematic diagram of exposure with inserting compensation pattern as the third embodiment of the present application is shown;

[0034] Figure 8 A schematic diagram of the method of the present application is shown. DETAILED DESCRIPTION

[0035] The present application is described below by specific embodiments, and other advantages and effects of the present application can be easily understood by those skilled in the art from the disclosure of the present specification. The present application can also be implemented or applied by other different embodiments, and each detail in the present specification can be modified or changed based on different views and applications without departing from the spirit of the present application.

[0036] Please refer to Figure 8 The present application provides a method for improving edge placement error, comprising:

[0037] Step one, providing a design layout, and first optical proximity correction of the design layout to obtain a first mask pattern; wherein at least one segment pattern is formed on the first mask pattern, so that the first mask pattern is stepped, and there is a first edge placement error between the first exposure profile of the first mask pattern and the design layout;

[0038] Step two, insert a compensation pattern at the position where the height difference of the first mask pattern exists, to obtain a second mask pattern;

[0039] Step three, obtain a second post-exposure profile according to the second mask pattern, so that the second edge placement error between the second post-exposure profile and the design layout is smaller than the first edge placement error.

[0040] In order to make the objects, advantages and features of the present application more clear, the following will combine the accompanying drawings to make a better description of the present application. Figures 1-8 The method for improving the edge placement error proposed in the present application will be further described. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict, the drawings are all in a very simplified form and all use non-precise proportions, which are only used to facilitate and clarify the purpose of assisting the description of the embodiments of the present application.

[0041] It should be noted that the terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, operation, device, component and / or combination thereof.

[0042] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0043] Step one, providing a design layout, and performing first optical proximity correction on the design layout to obtain a first mask pattern; wherein at least one segment pattern is formed on the first mask pattern, so that the first mask pattern is in a stepped shape, and a first edge placement error exists between a first post-exposure profile of the first mask pattern and the design layout;

[0044] In an alternative embodiment of the present application, the shape of the segment pattern in step one is a rectangle, and the critical dimension of the segment pattern needs to meet the design rule.

[0045] In one optional embodiment of the present invention, the segment pattern in step one is one, and the segment pattern is formed by optical proximity correction.

[0046] In one optional embodiment of the present invention, the segment pattern in step one is two, and the segment pattern is formed by optical proximity correction.

[0047] In one optional embodiment of the present invention, the shape of the compensation graphic in step one is rectangular, and the key dimensions of the fragment graphic must meet the design rules.

[0048] In an optional embodiment of the present invention, the first exposed contour in step one is wavy, and the distance between the first exposed contour and the design layout is defined as the first edge placement error.

[0049] For example, in such Figure 1 In the optical proximity correction shown, due to the influence of factors such as the light source and surrounding patterns 03, the design layout 02 needs to have a 021 added to the design layout 01 to compensate for the error. The corrected first photomask pattern 01 is as follows. Figure 2 As shown, segment graphics 011 and 012 are formed on both sides of the pattern, making the outline of the photomask pattern 01 step-shaped. The width D of segment graphics 011 and 012 is affected by optical proximity correction. In this embodiment, since the design layout 01 and the surrounding pattern 03 are symmetrically distributed, the width D of segment graphics 011 and 012 is equal. The first exposure outline 04 of the first photomask pattern 01 after exposure is wavy, and the first edge placement error d of the first exposure outline 04 is large. It should be understood that the width D of segment graphics 011 and 012 may also be different. Usually, the width D of the segment graphics is smaller than the side perpendicular to it. For ease of explanation, this side is defined as the width. In actual process, the width D of the segment graphics may also be larger than the side perpendicular to it.

[0050] Step 2: Insert a compensation pattern where there is a height difference in the first photomask pattern to obtain the second photomask pattern. That is, use the compensation pattern to reduce the height difference between the raised part of the first photomask pattern and other parts, thereby reducing the edge placement error caused by the height difference between the two patterns.

[0051] In an optional embodiment of the present invention, the shape of the compensation graphic in step one is rectangular. That is, when the height difference caused by the fragment graphic on the first photomask graphic is small, a single rectangular graphic can reduce the edge placement error.

[0052] In an optional embodiment of the present invention, the shape of the compensation pattern in step two is a stepped shape, and the height of each gradient of the stepped shape decreases sequentially from the higher side to the lower side of the first photomask pattern. That is, when the height difference caused by the fragment pattern on the first photomask pattern is large, a stepped compensation pattern needs to be set to reduce the edge placement error.

[0053] In an optional embodiment of the present invention, in step two, the compensation pattern and the first photomask pattern share the same corner, that is, one corner of the compensation pattern fits into the right angle of the segment pattern. It should be noted that there may also be a small gap between the compensation pattern and the segment pattern, as long as it can reduce the edge placement error.

[0054] In an optional embodiment of the present invention, in step two, the width X of the compensation graphic is X = D * P, where D is the width of the fragment graphic and P is greater than 0 and less than 1.

[0055] For example, such as Figure 2 If the width D (i.e., the height of fragment graphic 011 relative to the graphic below it) of fragment graphic 011 is 6.6 nm, then the height difference between fragment graphic 011 and other graphics is defined as 6.6 nm. Figure 3 The width of the compensation pattern 05 (i.e., the height of the compensation pattern 05 relative to the pattern below it) can be 3nm. In an optional embodiment of the present invention, the width of the rectangle in step two is X = D*P, where D is the width of the fragment pattern and P is 0.5, that is, the width of the rectangle is half the width D of the fragment pattern.

[0056] In an optional embodiment of the present invention, the compensation graphic in step two is composed of n rectangles with successively decreasing heights. The width of the nth rectangle is X = D * (P^n), where D is the width of the fragment graphic, P is greater than 0 and less than 1, and n is a positive integer greater than 2.

[0057] In an optional embodiment of the present invention, the compensation graphic in step two is composed of n rectangles with successively decreasing heights, and the width of the nth rectangle is X = D * (P^n), where D is the width of the fragment graphic, P is 0.5, and n is a positive integer greater than 2.

[0058] In an optional embodiment of the present invention, in step two, the compensation pattern is located on the concave edge of the first photomask pattern, which is in the shape of a step. The concave edge is the edge of a segment pattern on the other side of the first photomask pattern or the edge between two segment patterns, that is, the bottom edge of the segment pattern and the bottom edge of the compensation pattern are on the same straight line.

[0059] Step three, obtaining a second exposure profile according to the second mask pattern, so that the second edge placement error between the second exposure profile and the design layout is smaller than the first edge placement error, i.e. the edge placement error is reduced, and the second mask pattern can be used for the correction of the mask.

[0060] It should be noted that the first and second exposure profiles can be obtained by simulating the exposure result by software or measuring the actual exposure result.

[0061] In an alternative embodiment of the present application, the second exposure profile in step three is wavy, and the distance between the second exposure profile and the design layout is the second edge placement error.

[0062] In an alternative embodiment of the present application, the above-mentioned any method is used for optical proximity correction of a gate rectangular pattern in a logic circuit layout, and the rectangular pattern can be a gate pattern.

[0063] The present application also provides the following embodiments for detailed description:

[0064] Embodiment one

[0065] In the optical proximity correction as shown in Figure 1 , the design layout 02 needs to add an error compensation pattern 021 on the design layout 02 due to the influence of light source, surrounding patterns 03 and other factors, and the corrected first mask pattern 01 is as shown in Figure 2 , in which the profile of the mask pattern 01 is stepped due to the existence of the segment pattern 011 and the segment pattern 012 at the two side edges of the pattern, and the width D of the segment pattern 011 and the segment pattern 012 is affected by the optical proximity correction. In this embodiment, the design layout 01 and the surrounding patterns 03 are symmetrically distributed, so the width D of the segment pattern 011 and the segment pattern 012 is equal. The first exposure profile 04 after the exposure of the first mask pattern 01 is wavy, and the first edge placement error d of the first exposure profile 04 is large. The compensation pattern 05 is inserted at the right angle on the side of the segment pattern 011, and the shape of the compensation pattern 05 is a rectangle, and the width of the rectangle is half of the width D of the segment pattern. The compensation pattern 06 is inserted at the right angle on the side of the segment pattern 012, and the shape of the compensation pattern 06 is also a rectangle, and the width of the rectangle is half of the width D of the segment pattern. Thus, the second mask pattern is obtained. The edge placement error of the second exposure profile 07 of the second mask pattern with the compensation pattern 06 inserted is smaller than that of the first exposure profile 04 without the compensation pattern 06 inserted, and the wavy phenomenon of the pattern profile is reduced.

[0066] Embodiment two

[0067] In the optical proximity correction as shown in Figure 4In the optical proximity correction shown, a fragment pattern 081 is formed on one side edge of the corrected first mask pattern 08, the edge placement error of the first exposure profile 09 is large, and the profile is wavy. A compensation pattern 10 is inserted at the right angle of the fragment pattern 081, the compensation pattern 05 is in the shape of a rectangle, and the second mask pattern is obtained as shown in Figure 5 In the second mask pattern shown, the edge placement error of the second exposure profile 11 of the second mask pattern is small, the width of the rectangle can be half of the width D of the fragment pattern, and the wavy phenomenon of the pattern profile is reduced.

[0068] Embodiment Three

[0069] In the optical proximity correction shown, Figure 6 In the optical proximity correction shown, a fragment pattern 081 is formed on one side edge of the corrected first mask pattern 08, the edge placement error of the first exposure profile 09 is large, and the profile is wavy. A compensation pattern 10 is inserted at the right angle of the fragment pattern 081, the compensation pattern 05 is in the shape of a rectangle, and the second mask pattern is obtained as shown in

[0070] In the optical proximity correction shown, a fragment pattern 081 is formed on one side edge of the corrected first mask pattern 08, the edge placement error of the first exposure profile 09 is large, and the profile is wavy. A compensation pattern 10 is inserted at the right angle of the fragment pattern 081, the compensation pattern 05 is in the shape of a rectangle, and the second mask pattern is obtained as shown in

[0071] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical thought of the present application should be covered by the claims of the present application.

Claims

1. A method of improving edge placement error, characterized by, At least comprising: Step one, providing a design layout, and first optical proximity correction is performed on the design layout to obtain a first mask pattern; wherein at least one segment pattern is formed on the first mask pattern, so that the first mask pattern is in a stepped shape, and a first edge placement error exists between a first exposure profile of the first mask pattern and the design layout; Step two, a compensation pattern is inserted at a position where a height difference exists in the first mask pattern to obtain a second mask pattern, wherein the compensation pattern is located at a concave side of the first mask pattern in a stepped shape, the concave side is an edge opposite to one of the segment patterns or an edge between two of the segment patterns; the compensation pattern is in a rectangular shape or a stepped shape, when the compensation pattern is in a rectangular shape, a width X of the compensation pattern is equal to D*P; when the compensation pattern is in a stepped shape, the compensation pattern is composed of n rectangles with heights decreasing in sequence, and a width of the nth rectangle is X=D*(P^n) in sequence, n is a positive integer greater than 2; D is a width of the segment pattern, and P is a coefficient greater than 0 and less than 1; Step three, a second exposure profile is obtained according to the second mask pattern, so that a second edge placement error between the second exposure profile and the design layout is less than the first edge placement error.

2. The method of claim 1, wherein: The segment pattern in step one is in a rectangular shape.

3. The method of improving edge placement error of claim 1, wherein: The segment pattern in step one is one.

4. The method of improving edge placement error of claim 1, wherein: The segment pattern in step one is two.

5. The method of improving edge placement error of claim 1, wherein: The compensation pattern in step two shares the same corner with the first mask pattern.

6. The method of improving edge placement error of claim 1, wherein: The width X of the rectangular shape in step two is equal to D*P, wherein D is the width of the segment pattern, and P is 0.

5.

7. The method of improving edge placement error of claim 1, wherein: The compensation pattern in step two is composed of n rectangles with heights decreasing in sequence, and a width of the nth rectangle is X=D*(P^n) in sequence, D is the width of the segment pattern, P is 0.5, and n is a positive integer greater than 2.

8. The method of improving edge placement error of claim 1, wherein: The first exposure profile in step one is in a wavy shape, and a distance between the first exposure profile and the design layout is defined as the first edge placement error.

9. The method of improving edge placement error of claim 1, wherein: The second exposure profile in step three is in a wavy shape, and a distance between the second exposure profile and the design layout is defined as the second edge placement error.

10. The method of improving edge placement error of claim 1, wherein: The method is used for optical proximity correction of a rectangular pattern in a logic circuit layout.

11. The method of improving edge placement error of claim 10, wherein: The rectangular pattern is a gate pattern.

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