OPC (Optical Proximity Correction) method of metal layer pattern and metal layer

Abstract

According to the OPC correction method of the metal layer graph and the metal layer, the target graph is subjected to corner cutting, so that the distance between the minimum external angle and the external angle is increased, the target graph subjected to corner cutting serves as an OPC correction target, enough space is provided for OPC iteration correction, and the correction efficiency is improved. According to the invention, the problem that the pattern after OPC is not corrected in place due to the limitation of a photomask manufacturing rule in the OPC process can be avoided, and the containing degree of the wire end of the metal wire on the wafer to the contact hole is improved and is improved to 95% or above.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of semiconductor, and relates to an OPC correction method of a metal layer pattern and a metal layer. BACKGROUND

[0002] When the size of a lithography pattern is close to or less than the wavelength of exposure, due to the interference and diffraction effects of light, the image on the wafer will deviate from the pattern on the mask, and distortion will occur. For example, adjacent patterns can interfere with each other to form a "bridge" due to the diffraction effect, an isolated pattern that is too small can be "pinched" due to insufficient resolution, a line end can be "shrunk", a right angle on the mask becomes a "corner rounding" on the wafer, etc., so that the design pattern deviates from the actual imaging result.

[0003] Optical proximity correction (OPC) refers to a certain degree of correction and optimization of the original pattern through simulation, improvement of the diffraction effect, adjustment of the pattern on the mask to correct these distortions, so that the pattern exposed on the wafer meets the size of the lithography exposure, improves the resolution, and improves the common process window.

[0004] The pattern corrected by OPC will finally be written on the mask, so the pattern corrected by OPC needs to meet the mask manufacturing rules (MRC) of the mask factory. The MRC generally includes min line, min pitch, min area, inter corner to inter corner space, outer corner to outer corner space, etc. The work of OPC is to make the pattern finally exposed on the wafer meet the requirements on the premise of not violating the MRC.

[0005] For the back-end metal layer, due to the optical proximity effect, the line end will be shortened, so the coverage of the line end of the metal line to the upper and lower layer contact holes is a problem that must be considered, especially when the line end is adjacent to the upper and lower layer contact holes or the line end leaks out of the upper and lower layer contact holes in the original pattern, and the minimum outer corner to outer corner distance of the line end is small. The traditional OPC correction method will not be enough to cover the line end to the upper and lower layer contact holes.

[0006] Therefore, how to provide an OPC correction method of a metal layer pattern to improve the coverage of the line end to the upper and lower layer contact holes has become a technical problem to be solved by those skilled in the art. SUMMARY

[0007] In view of the above-mentioned defects of the prior art, the purpose of the present application is to provide an OPC correction method for metal layer patterns and a metal layer, which are used to solve the problem of insufficient inclusion of line ends of metal lines to upper and lower layer contact holes in the prior art.

[0008] To achieve the above-mentioned purpose and other related purposes, the present application provides an OPC correction method for metal layer patterns, comprising the following steps:

[0009] An original pattern is provided, which comprises a first metal pattern and a second metal pattern, the first metal pattern has a right-angle end near one end of the second metal pattern, the second metal pattern has a right-angle end near one end of the first metal pattern, and a contact hole is arranged above or below the end of the second metal pattern near the first metal pattern;

[0010] Process deviation compensation and process window expansion are performed on the original pattern to obtain a target pattern, which comprises a first target pattern and a second target pattern, wherein the end of the first target pattern near the second target pattern is recorded as a first end portion, and the end of the second target pattern near the first target pattern is recorded as a second end portion;

[0011] A preset region near the second end portion in the first end portion is removed, and a preset region near the first end portion in the second end portion is removed to obtain a chamfered target pattern;

[0012] The chamfered target pattern is taken as an OPC correction target to perform OPC correction to obtain a mask pattern.

[0013] Optionally, the step of performing process deviation compensation and process window expansion on the original pattern comprises:

[0014] The overall size difference of the original pattern is pre-compensated in the process of photolithography to etching;

[0015] Fine etching deviation compensation is performed according to the size and environment of the pattern;

[0016] The size of the metal pattern is increased to expand the process window according to the size and environment of the pattern.

[0017] Optionally, the removed region in the first end portion is a square region, and the side length of the square region is less than 10% to 20% of the line width of the first target pattern.

[0018] Optionally, the removed region in the second end portion is a square region, and the side length of the square region is less than 10% to 20% of the line width of the second target pattern.

[0019] Optionally, the end of the second metal pattern and the contact hole are edge-attached in the extension direction of the second metal pattern.

[0020] Optionally, the extension direction of the first metal pattern is perpendicular to the extension direction of the second metal pattern.

[0021] Optionally, the mask pattern comprises a first mask pattern and a second mask pattern, and the minimum outer corner pair distance of the first mask pattern and the second mask pattern is the minimum value allowed in the MRC outer corner pair distance.

[0022] The present application also provides a metal layer generated based on the mask pattern determined by the OPC correction method of the metal layer pattern of any one of the above.

[0023] As described above, in the OPC correction method of the metal layer pattern of the present application and the metal layer, the target pattern is chamfered to increase the minimum outer corner pair distance, and the chamfered target pattern is used as the OPC correction target, which provides sufficient space for OPC iteration correction, avoids the problem that the OPC correction after correction is not in place due to the limitation of mask manufacturing rules in the OPC correction process, improves the containment of the line end of the metal line on the wafer to the contact hole, and the containment is improved to more than 95%. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A flow chart of the OPC correction method of the metal layer pattern in the embodiment of the present application is shown.

[0025] Figure 2 A schematic diagram of the original pattern in the embodiment of the present application is shown.

[0026] Figure 3 A schematic diagram of the target pattern in the embodiment of the present application is shown.

[0027] Figure 4 A schematic diagram of the chamfered target pattern in the embodiment of the present application is shown.

[0028] Figure 5 A schematic diagram of the mask pattern in the embodiment of the present application is shown.

[0029] Figure 6 A comparison diagram of OPC correction in the present application and the comparative example is shown.

[0030] ELEMENT NUMBER EXPLANATION

[0031] 1 original pattern

[0032] 100 first metal pattern

[0033] 101 second metal pattern

[0034] 2 contact hole

[0035] 3 target pattern

[0036] 300 first target pattern

[0037] 3000 first end

[0038] 301 second target pattern

[0039] 3010 second end

[0040] 4 chamfer target pattern

[0041] 5 mask pattern

[0042] 500 first mask pattern

[0043] 501 second mask pattern

[0044] S1-S4 steps DETAILED DESCRIPTION

[0045] The present application is herein described, by way of example only, with the assistance of specific details to facilitate a thorough understanding of the application. The description is intended only by way of example and encompasses many alternatives, modifications and variations within the scope of the appended claims.

[0046] Reference will now be made to the drawings, wherein: Figures 1 to 6 It is to be understood that the above-mentioned arrangement is merely an example of the basic idea of the present application. Therefore, the actual implementation of the components shown in the drawings can vary greatly in number, shape and size, and the layout of the components can be more complicated. The drawings are not intended to limit the present application.

[0047] The present embodiment provides an OPC correction method for a metal layer pattern, please refer to Figure 1 , the OPC correction method for a metal layer pattern includes the following steps:

[0048] S1: providing an original pattern, the original pattern includes a first metal pattern and a second metal pattern, the first metal pattern has a right angle end near the second metal pattern, the second metal pattern has a right angle end near the first metal pattern, and a contact hole is arranged below the end of the second metal pattern near the first metal pattern;

[0049] S2: performing process deviation compensation and process window expansion on the original pattern to obtain a target pattern, the target pattern comprising a first target pattern and a second target pattern, wherein a first end portion of the first target pattern close to the second target pattern is marked as a first end portion, and a second end portion of the second target pattern close to the first target pattern is marked as a second end portion;

[0050] S3: removing a preset region of the first end portion close to the second end portion, and removing a preset region of the second end portion close to the first end portion to obtain a chamfered target pattern;

[0051] S4: taking the chamfered target pattern as an OPC correction target to perform OPC correction to obtain a mask pattern.

[0052] The OPC correction method for the metal layer pattern in the embodiment will be described in detail below with reference to the specific drawings.

[0053] First, refer to Figure 2 , step S1 is performed: an original pattern 1 is provided, the original pattern 1 comprising a first metal pattern 100 and a second metal pattern 101, a straight angle end of the first metal pattern 100 close to the second metal pattern 101, a straight angle end of the second metal pattern 101 close to the first metal pattern 101, and a contact hole 2 provided above or below an end of the second metal pattern 101 close to the first metal pattern 100.

[0054] As an example, the original pattern 1 is an ideal pattern determined in the design stage, i.e., a perfect pattern expected to be obtained on a wafer after photolithography and etching.

[0055] As an example, the extension direction (X direction) of the first metal pattern 100 is perpendicular to the extension direction (Y direction) of the second metal pattern 101, wherein in the X direction, the projection of the first metal pattern 100 and the projection of the second metal pattern 101 do not overlap, and in the Y direction, the projection of the first metal pattern 100 and the projection of the second metal pattern 101 do not overlap.

[0056] As an example, in the embodiment, in the Y direction, the contact hole 2 and the line end of the second metal pattern 101 are in contact, and the minimum value L of the line end outer corner to outer corner space of the first metal pattern 100 and the second metal pattern 101 is 0.14 μm, i.e., the minimum line end outer corner to outer corner space of the first metal pattern 100 and the second metal pattern 101 is small.

[0057] As an example, in the embodiment, the line width of the first metal pattern 100 is 0.14 μm, the line width of the second metal pattern 101 is 0.24 μm, and the size of the contact hole 2 is 0.12 μm.

[0058] Next, referring to Figure 3 , a step S2 is performed: process bias compensation and process window expansion are performed on the original pattern 1 to obtain a target pattern 3, the target pattern including a first target pattern 300 and a second target pattern 301, wherein a first end portion 3000 of the first target pattern 300 is close to an end of the second target pattern 301, and a second end portion 3010 of the second target pattern 301 is close to an end of the first target pattern 300.

[0059] As an example, the target pattern 3 is a pattern obtained by compensating the bias of each process in advance in a mask, i.e., the target pattern 3 is a pattern obtained by superimposing the entire process error on the original pattern 1. In the embodiment, the target pattern 3 is obtained by superimposing the process bias compensation and the process window expansion on the original pattern 1.

[0060] Specifically, the step of obtaining the target pattern 3 includes:

[0061] (1) First, the original pattern 1 is pre-compensated for the size difference between the photoetching and the etching process, which is called etch-bias compensation of the global pattern, i.e., global etch-bias, because the photoresist pattern will shrink or expand systemically due to plasma bombardment, chemical corrosion, etc. during etching, introducing systematic and global size bias;

[0062] (2) Elaborate etch-bias compensation is performed according to the size and environment of the pattern, because the etching rate will be affected by local pattern density changes, proximity effects, etc., introducing non-systematic and local size bias;

[0063] (3) The size of the metal pattern is increased to expand the process window according to the size and environment of the pattern, i.e., SSA, because the metal pattern usually needs to increase the critical dimension to improve the via coverage margin.

[0064] As an example, when the process model is established in the early stage, a lot of receipts will be collected on the wafer, including etch-bias pattern data and SSA pattern data, and the compensation amount and process window expansion amount obtained according to these data.

[0065] As an example, since the first metal pattern 100 has a right angle end close to the second metal pattern 101, in the first target pattern 300, the first end part 3000 is a right angle end; since the second metal pattern 101 has a right angle end close to the first metal pattern 100, in the second target pattern 301, the second end part 3010 is a right angle end.

[0066] Next, referring to Figure 4 , step S3 is performed: removing a preset region close to the second end part 3010 in the first end part 3000, and removing a preset region close to the first end part 3000 in the second end part 3010, to obtain a chamfered target pattern 4.

[0067] As an example, the first end part 3000 is a right angle end, and the right angle region close to the second end part 3010 in the first end part 3000 is chamfered, and the removed region is a square region.

[0068] As an example, the second end part 3010 is a right angle end, and the right angle region close to the first end part 3000 in the second end part 3010 is chamfered, and the removed region is a square region.

[0069] As an example, the line width of the first target pattern 300 is W1, the side length of the square region removed in the first end part 3000 is H1, and H1 is less than 10% to 20% of W1; the line width of the second target pattern 301 is W2, and the side length of the square region removed in the second end part 3010 is H2, and H2 is less than 10% to 20% of W2. That is, the size of the removed region needs to be less than 10% to 20% of the corresponding line width. Specifically, in this embodiment, H1 is 0.03 μm, and H2 is 0.03 μm.

[0070] Next, referring to Figure 5 , step S4 is performed: taking the chamfered target pattern as an OPC correction target, and performing OPC iterative correction to obtain a mask pattern 5.

[0071] As an example, the chamfered target pattern 3 is a pattern on a wafer after exposure of a photolithography process, the chamfered target pattern 3 is segmented, control points of each segment are set, a photoresist profile on the wafer is predicted according to an OPC model, edges of the pattern are moved, the photoresist profile is predicted again, and the iteration of the photoresist profile is performed until the iteration of the photoresist profile is closest to the chamfered target pattern 3, and the pattern is a mask pattern 5.

[0072] As an example, since the first target pattern 300 and the second target pattern 301 are chamfered in the chamfered target pattern 4, the outer corner-to-outer corner distance of the first target pattern 300 and the second target pattern 301 is increased, enough space is provided for OPC iteration correction, so that the OPC correction cannot converge due to the limitation of the outer corner-to-outer corner distance in mask manufacturing rules (MRC), and the problem that the OPC corrected pattern cannot be corrected to the right position due to the limitation of mask manufacturing rules in the OPC correction process can be avoided, so as to improve the inclusion of the line end of the metal line on the wafer to the contact hole, and the inclusion is improved to more than 95%.

[0073] Specifically, in the embodiment, the limitation of the outer corner-to-outer corner distance in the mask manufacturing rules is 0.1 μm, that is, the minimum size of the allowed outer corner-to-outer corner distance in the mask pattern 5 is 0.1 μm.

[0074] As an example, the mask pattern 5 includes a first mask pattern 500 and a second mask pattern 501, and the minimum outer corner-to-outer corner distance of the first mask pattern 500 and the second mask pattern 501 is 0.1 μm.

[0075] As an example, please refer to Figure 6 , which shows the comparison of OPC correction in the present application and the comparative example. In the comparative example, after the original pattern is subjected to process deviation compensation and process window expansion to obtain a target pattern, the target pattern is not chamfered, and the target pattern is directly used as the OPC correction target for OPC correction, and the inclusion of the line end of the metal line on the wafer to the contact hole is 90%. In the present application, the target pattern is chamfered to obtain a chamfered target pattern, and the chamfered target pattern is used as the OPC correction target for OPC correction, and the inclusion of the line end of the metal line on the wafer to the contact hole is 96%. The inclusion of the line end of the metal line to the contact hole is improved, and the electrical problem caused by the metal line in the later stage is avoided.

[0076] The embodiment also provides a metal layer, which is generated based on the mask pattern determined by the OPC correction method of the metal layer pattern, that is, after the mask pattern is obtained by the OPC correction method of the metal layer pattern, the mask pattern is used as a mask pattern, and photolithography and etching processes are performed to obtain the metal layer.

[0077] In summary, the OP C correction method of the metal layer pattern and the metal layer of the present application chops the corners of the target pattern to increase the distance of the minimum outer corner to the outer corner, uses the target pattern after corner chopping as the OP C correction target, gives enough space for OP C iteration correction, can avoid the problem that the OP C correction after correction is not in place due to the mask manufacturing rule limitation in the OP C correction process, improves the inclusion of the line end of the metal line on the wafer to the contact hole, and the inclusion is improved to more than 95%. Therefore, the present application effectively overcomes the various shortcomings in the prior art and has high industrial utilization value.

[0078] 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 completed by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A method for OPC correction of a metal layer pattern, characterized in that, The method comprises the following steps: providing an original pattern, the original pattern comprising a first metal pattern and a second metal pattern, the first metal pattern having a right-angle end close to one end of the second metal pattern, the second metal pattern having a right-angle end close to one end of the first metal pattern, and a contact hole being arranged above or below the end of the second metal pattern close to the first metal pattern; carrying out process deviation compensation and process window expansion on the original pattern to obtain a target pattern, the target pattern comprising a first target pattern and a second target pattern, wherein the first end of the first target pattern close to the second target pattern is recorded as a first end portion, and the second end of the second target pattern close to the first target pattern is recorded as a second end portion; removing a preset region of the first end portion close to the second end portion and removing a preset region of the second end portion close to the first end portion to obtain a chamfered target pattern; taking the chamfered target pattern as an OPC correction target to carry out OPC correction to obtain a mask pattern.

2. The OPC correction method of a metal layer pattern according to claim 1, wherein The step of carrying out process deviation compensation and process window expansion on the original pattern comprises: carrying out size difference pre-compensation of a lithography-to-etching process on the original pattern as a whole; carrying out fine etching deviation compensation according to the size of the pattern and the environment; increasing the size of the metal pattern according to the size of the pattern and the environment to expand the process window.

3. The OPC correction method of a metal layer pattern according to claim 1, wherein: The removed region of the first end portion is a square region, and the side length of the square region is less than 10%-20% of the line width of the first target pattern.

4. The OPC correction method of a metal layer pattern according to claim 1, wherein: The removed region of the second end portion is a square region, and the side length of the square region is less than 10%-20% of the line width of the second target pattern.

5. The method of claim 1, wherein: In the extension direction of the second metal pattern, the end portion of the second metal pattern and the contact hole are arranged in abutment.

6. The method of claim 1, wherein: The extension direction of the first metal pattern is perpendicular to the extension direction of the second metal pattern.

7. The method of claim 1, wherein: the metal layer pattern is a metal layer pattern of a semiconductor device. The mask pattern comprises a first mask pattern and a second mask pattern, and the minimum outer corner-to-outer corner distance of the first mask pattern and the second mask pattern is the minimum value allowed in the outer corner-to-outer corner distance in the MRC.

8. A metal layer, characterized by: The metal layer is generated based on the mask pattern determined by the OPC correction method of the metal layer pattern in any one of claims 1-7.

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