阅读说明：本技术 一种光学临近效应修正方法及装置 (Optical proximity effect correction method and device ) 是由 陈志立 于 2020-04-08 设计创作，主要内容包括：本发明公开了一种光学临近效应修正方法及装置,其中,光学临近效应修正方法包括：获取原始目标图形,并对所述原始目标图形进行预处理,形成二次目标图形,使得二次目标图形满足预设工艺规则；将所述二次目标图形进行光学临近效应修正处理,获取修正图形；根据所述修正图形获取所述原始目标图形的模拟轮廓；计算所述模拟轮廓与所述原始目标图形之间的偏差；根据所述偏差值判断所述修正图形是否满足工艺需求。本发明提供了一种光学临近效应修正方法及装置,以解决现有光学临近效应修正后,光刻图形失真严重的问题。(The invention discloses an optical proximity effect correction method and device, wherein the optical proximity effect correction method comprises the following steps: acquiring an original target graph, and preprocessing the original target graph to form a secondary target graph so that the secondary target graph meets a preset process rule; carrying out optical proximity effect correction processing on the secondary target graph to obtain a corrected graph; acquiring a simulation outline of the original target graph according to the corrected graph; calculating the deviation between the simulated contour and the original target graph; and judging whether the corrected graph meets the process requirements or not according to the deviation value. The invention provides an optical proximity effect correction method and device, which are used for solving the problem that photoetching graphs are seriously distorted after the existing optical proximity effect correction.)

1. An optical proximity correction method, comprising:

acquiring an original target graph, and preprocessing the original target graph to form a secondary target graph so that the secondary target graph meets a preset process rule;

carrying out optical proximity effect correction processing on the secondary target graph to obtain a corrected graph;

acquiring a simulation outline of the original target graph according to the corrected graph;

calculating the deviation between the simulated contour and the original target graph; and judging whether the corrected graph meets the process requirements or not according to the deviation value.

2. The method according to claim 1, wherein the predetermined process rule comprises: the main body does not comprise a sunken block-shaped notch;

preprocessing the original target graph to form a secondary target graph, comprising:

and if the original target graph comprises the sunken block-shaped gap on the main body, extending along the contour line of the main body to form a secondary target graph, so that the sunken block-shaped gap on the main body is filled.

3. The method for correcting optical proximity effect according to claim 2, wherein if the original target pattern includes a block notch recessed in the main body, extending along a contour of the main body to form a secondary target pattern, so that the block notch recessed in the main body is filled, the method comprises:

and if the original target graph comprises a block-shaped gap formed by the sunken corner areas of the two mutually vertical contour lines of the main body, filling the corner areas along the contour lines of the main body to form a right-angle area, and forming a secondary target graph.

4. The optical proximity correction method according to claim 2,

the smallest dimension of the block-shaped gap is less than or equal to 10 nm.

5. The optical proximity effect correction method according to claim 2, wherein the recessed block-shaped notch comprises a plurality of notch units arranged in a step-like manner; the notch units correspond to the step-shaped structures on the main body one by one;

if the original target pattern comprises a sunken block-shaped gap on the main body, extending along the contour line of the main body to form a secondary target pattern, so that the sunken block-shaped gap on the main body is filled, comprising:

and if the block-shaped gap of the original target pattern comprises a plurality of gap units which are distributed in a step-shaped manner, filling the gap units, and/or removing the step structures corresponding to the gap units to form a secondary target pattern, so that the minimum size of the sunken block-shaped gap is larger than 10 nm.

6. The OPC method as claimed in claim 5, wherein the original target pattern comprises 2 notch units; one of the gap units is filled, and the step structure corresponding to the other gap unit is removed to form the secondary target pattern.

7. The OPC method as claimed in claim 5, wherein the original target pattern comprises 3 notch units; and filling the gap units corresponding to the two step structures close to the main body to form the secondary target pattern.

8. The OPC method as claimed in claim 1, wherein the predetermined process rule comprises at least one of the following:

the width of the line is greater than or equal to a width threshold;

the width of the gap between adjacent lines is greater than or equal to a gap threshold; and the number of the first and second groups,

the distance between the centerline of the line and the centerline of the adjacent gap is greater than or equal to a spacing threshold;

preprocessing the original target graph to form a secondary target graph, comprising:

if the main body of the original target graph does not meet the preset process rule, resetting the main body to meet the preset process rule and forming a secondary target graph.

9. The OPC method as claimed in claim 1, wherein the original target pattern further comprises an initially corrected optical auxiliary line; the preset process rule comprises at least one of the following items:

in two optical auxiliary lines with vertical extension directions, the gap between the side edge of the first optical auxiliary line and the end of the second optical auxiliary line is greater than or equal to a first auxiliary gap threshold value;

the width of the first optical auxiliary line is greater than or equal to a first auxiliary width threshold value;

the width of the optical auxiliary line arranged in the gap between the two parts of the main bodies is less than or equal to a second auxiliary width threshold value; and the number of the first and second groups,

the gap between the optical auxiliary line close to the dummy pattern and the dummy pattern is greater than or equal to a second auxiliary gap threshold value;

preprocessing the original target graph to form a secondary target graph, comprising:

if the optical auxiliary line of the original target pattern does not meet the preset process rule, resetting the optical auxiliary line to meet the preset process rule to form a secondary target pattern.

10. The optical proximity correction method according to claim 9,

the first auxiliary gap threshold is 20 nm; the first auxiliary width threshold is 10 nm; the second auxiliary width threshold is 40 nm; the second auxiliary gap threshold is 200 nm.

11. The optical proximity correction method according to claim 1, further comprising:

and carrying out optical proximity effect correction processing on the secondary target pattern for multiple times until the deviation value between the obtained simulated contour and the original target pattern meets the process requirement.

12. An optical proximity correction apparatus, operable to perform the optical proximity correction method of any one of claims 1 to 11, comprising:

the secondary processing module is used for acquiring an original target graph and preprocessing the original target graph to form a secondary target graph so that the secondary target graph meets a preset process rule;

the correction module is used for carrying out optical proximity effect correction processing on the secondary target graph to obtain a corrected graph;

the contour module is used for acquiring a simulated contour of the original target graph according to the corrected graph;

the deviation calculation module is used for calculating the deviation between the simulated contour and the original target graph;

and the iteration module is used for circularly calling the correction module and the contour module until the deviation value acquired by the deviation calculation module meets the process requirement.

Technical Field

The invention relates to the technical field of semiconductors, in particular to an optical proximity effect correction method and device.

Background

As integrated circuit devices are scaled down and integrated, the critical dimension of each film layer is smaller and smaller, and in the semiconductor process, the mask pattern is often transferred to a silicon wafer by photolithography to form each film layer pattern, but the size of each device is reduced, and the photolithography accuracy is lower.

Specifically, in the photolithography process, due to the interference Effect and diffraction Effect of light, there is a certain distortion and deviation between the actual photolithography pattern and the mask pattern on the silicon wafer, i.e. Optical Proximity Effect (OPE). Optical proximity effects may cause right angle corners to be rounded, line widths of the lithographic pattern to increase or decrease, and the like. In order to avoid the distortion of the lithography pattern caused by the OPE, the prior art adopts an Optical Proximity Correction (OPC) method to modify the mask pattern in advance, so that the modified pattern can make up for the defects caused by the OPE as much as possible, and then the modified mask pattern is transferred to a silicon wafer to generate the lithography pattern.

In practical applications, due to the diversification of the original target patterns, the difference between the lithography pattern and the original target patterns still exists, and in some cases, the lithography pattern profile cannot cover the target profile, so that the distortion of the lithography pattern is serious. The pattern distortion is mainly characterized by line width deviation, line shortening, missing patterns or continuous lines, corner rounding and the like. The distortion of the lithographic pattern directly affects the device performance, thereby reducing the production yield.

Disclosure of Invention

The embodiment of the invention provides an optical proximity effect correction method and device, and aims to solve the problem that photoetching graphs are seriously distorted after the existing optical proximity effect correction.

In a first aspect, an embodiment of the present invention provides an optical proximity correction method, including:

acquiring an original target graph, and preprocessing the original target graph to form a secondary target graph so that the secondary target graph meets a preset process rule;

carrying out optical proximity effect correction processing on the secondary target graph to obtain a corrected graph;

acquiring a simulation outline of the original target graph according to the corrected graph;

calculating the deviation between the simulated contour and the original target graph; and judging whether the corrected graph meets the process requirements or not according to the deviation value.

In a second aspect, an embodiment of the present invention further provides an optical proximity correction apparatus, configured to perform the optical proximity correction method provided in any embodiment of the present invention, where the optical proximity correction apparatus includes:

the secondary processing module is used for acquiring an original target graph and preprocessing the original target graph to form a secondary target graph so that the secondary target graph meets a preset process rule;

the correction module is used for carrying out optical proximity effect correction processing on the secondary target graph to obtain a corrected graph;

the contour module is used for acquiring a simulated contour of the original target graph according to the corrected graph;

the deviation calculation module is used for calculating the deviation between the simulated contour and the original target graph;

and the iteration module is used for circularly calling the correction module and the contour module until the deviation value acquired by the deviation calculation module meets the process requirement.

In the invention, before the optical proximity effect correction is carried out on a target graph, an original target graph is preprocessed, specifically, the original target graph which can influence the accuracy of an exposure graph finally exposed on a film layer is corrected and adjusted in advance to form a secondary target graph, namely, the original target graph which does not meet the preset process rule is adjusted to form a secondary target graph which meets the preset process rule, the optical proximity effect correction is carried out on the secondary target graph to obtain a corrected graph, the corrected graph is simulated and calculated to obtain a simulated contour deviation value, the simulated contour is compared with the original target graph, if the simulated contour meets the process requirement, the final accurate corrected graph can be determined, and the exposure graph of which the simulated contour is close to the original target graph can be obtained according to the corrected graph. Compared with the method for directly correcting the original target pattern by the optical proximity effect, the method for correcting the original target pattern by the optical proximity effect has the advantages that the original target pattern is preprocessed, the pattern factor causing the final simulation outline deformation is eliminated, the simulation outline is close to the original target pattern, the problem of serious exposure pattern distortion is solved, the performance of a finally formed device is improved, the production yield is improved, the optical proximity effect correction period can be effectively shortened, and the exposure and photoetching efficiency is improved.

Drawings

FIG. 1 is a flow chart illustrating a method for optical proximity correction according to an embodiment of the present invention;

FIG. 2 is a flow chart illustrating another optical proximity correction method according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of an original target pattern according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of another original target pattern provided by the embodiment of the present invention;

FIG. 5 is a schematic diagram of a comparative structure of an original target pattern and a secondary target pattern according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of a comparative structure of another original target pattern and a secondary target pattern provided by an embodiment of the present invention;

FIG. 7 is a schematic diagram of a comparative structure of another original target pattern and a secondary target pattern provided by an embodiment of the present invention;

FIG. 8 is a flow chart illustrating another optical proximity correction method according to an embodiment of the present invention;

FIG. 9 is a schematic structural diagram of another original target pattern provided by an embodiment of the present invention;

FIG. 10 is a schematic diagram of a line structure in a target pattern according to an embodiment of the present invention;

FIG. 11 is a flow chart illustrating another optical proximity correction method according to an embodiment of the present invention;

FIG. 12 is a schematic structural diagram of an optical assist line according to an embodiment of the present invention;

FIG. 13 is a schematic structural diagram of another optical assist line provided in the embodiments of the present invention;

FIG. 14 is a schematic structural diagram of another optical assist line provided in the embodiments of the present invention;

fig. 15 is a schematic structural diagram of an optical proximity correction apparatus according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

In the semiconductor process, in the key film layer of the 0.18 micron and below technology node, for example, the key sizes of the active region layer, the gate oxide layer and the metal connection layer are smaller and smaller, some key sizes are already close to and set smaller than the wavelength of light used in the photoetching step, the pattern transfer is easily affected by light to generate deviation, namely, the optical proximity effect, and the factor for forming the optical proximity effect is that when a light beam penetrates through a mask pattern on a mask plate and is projected on the photoresist, on one hand, the energy distribution and the phase distribution of the intensity spectrum of the light beam have certain distortion relative to the ideal image spectrum, namely, the diffraction effect, on the other hand, the light beam penetrates through the photoresist and is reflected back through the semiconductor substrate of the chip to generate the interference phenomenon, so that the light beam can be repeatedly exposed, and the actual exposure of the photoresist layer is changed. Generally, an ideal pattern (target pattern) to be formed on a film layer can be corrected through an optical proximity effect correction model to form a corrected pattern, so that an exposure pattern (photoetching pattern) formed on the film layer by the corrected pattern is close to the target pattern, but some patterns in the target pattern are arranged, so that the photoetching pattern formed after the target pattern is corrected is seriously distorted and generates larger distortion.

Specifically, an embodiment of the present invention provides an optical proximity correction method, and fig. 1 is a schematic flow chart of the optical proximity correction method provided in the embodiment of the present invention, as shown in fig. 1, the optical proximity correction method includes the following steps:

s110, obtaining an original target graph, and preprocessing the original target graph to form a secondary target graph, so that the secondary target graph meets a preset process rule.

The original target pattern includes a pattern that a user finally wants to form on a chip or a silicon wafer, and the embodiment pre-designs a mask pattern on a mask plate, so that a photoetching pattern close to the original target pattern is formed on a photoetching adhesive layer after the mask pattern is subjected to a photoetching process.

In order to prevent the distortion of the photoetching pattern finally formed on the silicon wafer after the original target pattern is corrected by the optical proximity effect model from being serious, the original target pattern needs to be preprocessed in advance to remove structural factors causing the distortion of the photoetching pattern. Specifically, if the pattern distortion mainly appears as line width deviation, the structure causing the line width deviation is adjusted, deleted or filled, and if the pattern distortion mainly appears in a continuous strip, the size and the space of the target pattern are reset and adjusted to the extent that the photoetching pattern distortion cannot be caused. Specifically, in this embodiment, a preset process rule is set according to a relationship between distortion and a target pattern, a portion of an original target pattern that does not meet the preset process rule is adjusted and processed to obtain a secondary target pattern, and the secondary target pattern is corrected by an optical proximity effect, so that a structure that is prone to distortion is avoided to a great extent. It should be understood that the preprocessing of the original target pattern includes checking the original target pattern according to a preset process rule, and preprocessing the checked original target pattern that does not conform to the preset process rule.

And S120, carrying out optical proximity effect correction processing on the secondary target pattern to obtain a corrected pattern.

Specifically, the present embodiment may modify the target layout pattern by a modification model to obtain a modified pattern, for example, the optical proximity modification model includes an optical model (optical model) and a photoresist model (resist model). In the optical proximity correction process, an optical model is used firstly, the optical model simulates exposure light beams to irradiate a mask pattern, the space light intensity distribution on the surface of a silicon wafer is diffracted through a lens group, then a photoresist model is used, the photoresist model simulates the light intensity distribution on the surface of the silicon wafer on photoresist, and the photoresist part above a certain exposure threshold value is denatured through chemical reaction so as to be dissolved in developing solution. The photoresist model in this embodiment adopts a constant threshold value photoresist model (i.e., a photoresist exposure reference threshold value is fixed), and compared with a variable threshold value photoresist model (variable threshold value photoresist model), simplifying the photoresist model can avoid the complication caused by obtaining an optical proximity correction model by a complicated photoresist model.

And S130, acquiring the simulation outline of the original target graph according to the corrected graph.

The correction graph is subjected to simulation of a mask exposure process to obtain a simulation profile, the simulation profile is a simulated exposure graph or a simulated photoetching graph, although the simulation profile is not completely the same as the original target graph and has a certain error, the simulation profile can be further attached to the original target graph, and the optical proximity effect correction effect is improved.

S140, calculating the deviation between the simulation contour and the original target graph; and judging whether the corrected graph meets the process requirements or not according to the deviation value.

If the deviation between the simulated contour and the original target pattern meets the process requirement, the optical proximity effect correction effect is qualified, a mask pattern can be formed according to the corrected pattern, the photoetching pattern formed by exposing the mask pattern has high precision and is close to the original target pattern, and the correction precision and the mask quality are improved.

Optionally, the optical proximity correction method may further include: and carrying out optical proximity effect correction processing on the secondary target graph for multiple times until the deviation value between the obtained simulated contour and the original target graph meets the process requirement.

In this embodiment, a final corrected pattern may not be directly obtained through one optical proximity effect correction process, and in more cases, a mask pattern needs to be formed by performing the optical proximity effect correction process multiple times to obtain a more accurate corrected pattern, so that steps S120 to S140 need to be performed multiple times to obtain the final corrected pattern.

In the embodiment of the invention, before the optical proximity effect correction is carried out on the target graph, the original target graph is preprocessed, specifically, the original target graph which can influence the accuracy of the exposure graph finally exposed on the film layer is corrected and adjusted in advance to form a secondary target graph, namely, the original target graph which does not meet the preset process rule is adjusted to form the secondary target graph which meets the preset process rule, the optical proximity effect correction is carried out on the secondary target graph to obtain the correction graph, the simulation exposure process is carried out on the correction graph to form the simulation profile, the simulation profile is compared with the original target graph, if the deviation value meets the process requirement, the final accurate correction graph can be determined, and the exposure graph close to the original target graph can be obtained according to the correction graph. Compared with the method of directly correcting the optical proximity effect of the original target graph, the method has the advantages that the original target graph is preprocessed, graph factors causing the deformation of the final simulation outline are eliminated, the simulation outline is close to the original target graph, the problem of serious exposure graph distortion is solved, the performance of a finally formed device is improved, and the production yield is improved.

Optionally, the preset process rule may include: the main body does not comprise a sunken block-shaped notch; correspondingly, the embodiment of the present invention specifically limits the preprocessing process performed on the original target pattern, as shown in fig. 2, and fig. 2 is a schematic flow chart of another optical proximity correction method provided in the embodiment of the present invention, as shown in fig. 2, the optical proximity correction method includes the following steps:

s210, obtaining an original target graph, and if the original target graph comprises a concave block-shaped gap on the main body, extending along the contour line of the main body to form a secondary target graph so that the concave block-shaped gap on the main body is filled.

The target pattern is generally an irregular pattern, for example, a shape in which a long bar is protruded from the main body and a shape in which a slit is recessed from the main body. The preset process rule in this embodiment may include: the main body does not include a concave block-shaped notch, and fig. 3 is a schematic structural view of an original target pattern provided by an embodiment of the present invention. Fig. 4 is a schematic structural diagram of another original target pattern provided in the embodiment of the present invention. As shown in fig. 3 and 4, the original pattern may include a block gap 111 formed by recessing on the main body 11, if the optical proximity correction is directly performed on the original target pattern, the block-shaped notch 111 greatly affects the accuracy of the finally obtained simulated contour, causing the simulated contour to be distorted, as shown in fig. 3, the contour formed by the dotted line in fig. 3 is the simulated contour 12, it can be seen that the structure of the block-shaped gap 111 makes the distortion rate of the original target pattern through the OPC model larger, the simulated outline 12 can not cover the basic main body 11, so that the shape of the simulated contour can be gradually improved only by modifying the simulated contour through the optical proximity effect modification model for a plurality of times, the whole optical proximity correction process is complex, the cycle time is prolonged, and the accuracy of the finally formed mask pattern is not high enough. Therefore, in this embodiment, the original target pattern may be preprocessed to eliminate the block notch 111 recessed on the main body, so as to form a secondary target pattern, as shown in fig. 5, fig. 5 is a schematic diagram of a comparison structure between the original target pattern and the secondary target pattern provided in the embodiment of the present invention. The secondary target pattern 13 can be formed by extending along the contour line of the main body 11, as shown in fig. 5, the secondary target pattern 13 is formed by filling the block-shaped gap 111 recessed on the original target pattern, and the deviation between the simulated profile 12 and the original target pattern is small in the simulated profile 12 formed by correcting the secondary target pattern 13 by the optical proximity effect correction model, so that the qualified mask pattern can be obtained after the simulated profile 12 is corrected by the optical proximity effect correction model for a small number of times.

On the basis of the above embodiment, with continuing reference to fig. 5, if the block-shaped notch 111 is formed at a corner or corner, the step 210, that is, if the original target pattern includes a recessed block-shaped notch on the main body, then extending along the contour line of the main body to form a secondary target pattern, so that the recessed block-shaped notch on the main body is filled, includes: and if the original target graph comprises a block-shaped gap formed by the depression of the corner areas of the two mutually vertical contour lines of the main body, filling the corner areas along the contour lines of the main body to form a right-angle area, and forming a secondary target graph. The block-shaped notch 111 at the corner or corner is used as an important position limiting part, and the influence of the change on the simulated contour 12 is large, in this embodiment, the block-shaped notch 111 at the corner or corner is filled first, so that the block-shaped notch 111 at the corner or corner forms a right-angle area to form the secondary target pattern 13, and the secondary target pattern 13 makes the simulated contour 12 closer to the original target pattern, thereby improving the correction accuracy.

Optionally, the smallest dimension of the bulk notch 111 is less than or equal to 10 nm. When the minimum size of the block-shaped notch 111 is less than or equal to 10nm, the influence on the distortion of the simulated contour 12 is larger, so when the minimum size of the block-shaped notch 111 is less than or equal to 10nm, the filling and repairing process can be performed on the block-shaped notch 111, and when the minimum size of the block-shaped notch 111 is greater than 10nm, the influence on the simulated contour 12 is smaller, and the block-shaped notch can be processed as a normal main structure.

The block-shaped notch 111 recessed in the main body shown in fig. 4 and 5 is in a rectangular shape, although other shapes may exist in the block-shaped notch 111, in a specific implementation manner of this embodiment, as shown in fig. 6, fig. 6 is a schematic diagram of a comparative structure between another original target pattern and a secondary target pattern provided in an embodiment of the present invention. The recessed block-shaped notch 111 may further include a plurality of notch units 111a arranged in a step-like manner, and correspondingly, the main body 11 includes step-like structures 112 corresponding to the notch units 111a one-to-one. Correspondingly, if the original target pattern includes the block-shaped notch 111 recessed in the main body 11, the secondary target pattern 13 is formed to extend along the contour line of the main body 11, so that the block-shaped notch 111 recessed in the main body 11 is filled, including: if the block-shaped notch 111 of the original target pattern includes a plurality of notch units 111a arranged in a step-like manner, the notch units 111a are filled, and/or the step structures 112 corresponding to the notch units 111a are removed, so as to form the secondary target pattern 13, such that the minimum size of the recessed block-shaped notch is greater than 10 nm.

As shown in fig. 6, when the block-shaped notch 111 of the original target pattern includes a plurality of notch units 111a, it may not be possible to directly fill the entire block-shaped notch 111, the present embodiment can reduce the number of the notch units 111a corresponding to the block-shaped notches 111 and the stepped structures 112 on the main body 11 by filling the notch units 111a or removing the stepped structures 112, that is, the minimum size of the block-shaped notch 111 is increased by reducing, for example, the side length of the notch unit 111a of the original target pattern in fig. 6 is three times the minimum size of the block-shaped notch 111, the minimum size of the recessed block-shaped notch of the processed secondary target pattern 13 is three times the side length of the notch unit 111a, thereby increasing the minimum size of the block-shaped gap of the secondary target pattern 13, so that the simulated contour 12 is closer to the original target pattern, and the correction precision is improved.

Optionally, with continued reference to fig. 6, the number of the notch units 111a included in the original target graph is 2; the gap unit 111a corresponding to one of the step structures 112 is filled, and the other step structure 112 is removed to form the secondary target pattern 13. Then, compared with the original target pattern and the secondary target pattern 13, the number of steps of the block step structure 112 is reduced, the minimum size of the block gap is increased, the simulated contour 12 obtained from the secondary target pattern 13 is closer to the original target pattern, and the correction accuracy is improved.

Optionally, referring to fig. 7, fig. 7 is a schematic diagram of a comparative structure of another original target pattern and a secondary target pattern provided in the embodiment of the present invention, where the number of the notch units 111a included in the original target pattern is 3; the gap units 111a corresponding to the two step structures 112 close to the main body 11 are filled to form the secondary target pattern 13, compared with the original target pattern and the secondary target pattern 13, the number of steps of the block step structure 112 is reduced, the number of steps is changed from three to one, the minimum size of the block gap is twice of the side length of the gap unit 111a, the simulated contour 12 obtained by the secondary target pattern 13 is closer to the original target pattern, and the correction precision is improved.

S220, carrying out optical proximity correction processing on the secondary target graph to obtain a corrected graph.

And S230, acquiring the simulated contour of the original target graph according to the corrected graph.

S240, calculating the deviation between the simulation contour and the original target graph; and judging whether the corrected graph meets the process requirements or not according to the deviation value.

In the embodiment, the original target pattern is preprocessed to fill the block gap sunken in the main body of the original target pattern, so that a secondary target pattern is formed, the secondary target pattern is used as an operation object to correct the optical proximity effect modification model, instead of correcting the optical proximity effect modification model on the original target pattern, so that the deviation rate of the obtained simulated contour is small, the optical proximity effect modification period is favorably shortened, the accuracy of the final mask pattern is improved, and the manufacturing yield of the device is high.

Optionally, the preset process rule includes at least one of the following items: the width of the line is greater than or equal to a width threshold; the width of the gap between adjacent lines is greater than or equal to a gap threshold; and the distance between the centerline of the line and the centerline of the adjacent gap is greater than or equal to the spacing threshold; correspondingly, the embodiment of the present invention specifically limits the preprocessing process performed on the original target pattern, as shown in fig. 8, where fig. 8 is a schematic flow chart of another optical proximity correction method provided in the embodiment of the present invention, and as shown in fig. 8, the optical proximity correction method includes the following steps:

s310, obtaining an original target graph, and if a main body of the original target graph does not meet a preset process rule, resetting the main body to meet the preset process rule to form a secondary target graph.

In this embodiment, the original target pattern is preprocessed to form a secondary target pattern, and the specific process includes judging and detecting each preset process rule one by one, screening out a case that does not meet each preset process rule, and resetting the target pattern to form the secondary target pattern.

In this embodiment, the size and arrangement of the lines of the original target pattern are set to reduce distortion caused by the finally formed simulated contour. Exemplarily, as shown in fig. 9, fig. 9 is a schematic structural diagram of another original target pattern provided by the embodiment of the present invention. If the distance between the ends of the two lines 112 in fig. 9 is too small, the simulated contour 12 formed after the optical proximity correction model of the original target pattern is corrected is prone to be continuous, which causes an error in the mask image.

In this embodiment, a preset process rule is set, where the preset process rule may include at least one of the following items, specifically, as shown in fig. 10, fig. 10 is a schematic structural diagram of a line in a target graph according to an embodiment of the present invention. If the target pattern includes a plurality of parallel lines 112, the width d1 of the lines may be defined to be greater than or equal to the width threshold, the width d2 of the gap between adjacent lines 112 may be defined to be greater than or equal to the gap threshold, and the distance d3 between the center line L1 of the line 112 and the center line L2 of the adjacent gap may be defined to be greater than or equal to the spacing threshold, so as to prevent the adjacent lines 112 from interacting with each other, and to make the simulated contour easily distorted. Therefore, if at least one item which does not meet the preset process rule exists in the original target pattern, the width and the position of the line 112 of the target pattern are adjusted again to form a secondary target pattern which meets the preset process rule.

Alternatively, the width threshold may be 50 nm; the gap threshold may be 100 nm; the separation threshold may be 200 nm. When the width d1 of the lines 112 is greater than or equal to 50nm, the width d2 of the gap between the adjacent lines 112 is greater than or equal to 100nm, and the distance d3 between the center line L1 of the line 112 and the center line L2 of the adjacent gap is greater than or equal to 200nm, the adjacent lines 112 are not easily affected with each other, the correction rate of the optical proximity effect correction model is increased, the correction period is shortened, and the accuracy of the finally formed photoetching pattern is improved.

And S320, carrying out optical proximity correction processing on the secondary target graph to obtain a corrected graph.

And S330, acquiring the simulated contour of the original target graph according to the corrected graph.

S340, calculating the deviation between the simulation contour and the original target graph; and judging whether the corrected graph meets the process requirements or not according to the deviation value.

In this embodiment, the size and the position of the line in the original target pattern are set to form a secondary target pattern, so that the secondary target pattern meets the preset process rule, and the secondary target pattern is used as a correction object of the optical proximity effect correction model, thereby avoiding distortion and error caused by directly correcting the original target pattern, and improving the efficiency of the optical proximity effect correction process.

The steps S210 to S240, and the steps S310 to S340 are all set according to the size and position of the exposure pattern, and optionally, the original target pattern may further include an optical assist line; the preset process rule comprises at least one of the following items: in two optical auxiliary lines with vertical extension directions, the gap between the side edge of the first optical auxiliary line and the end of the second optical auxiliary line is greater than or equal to a first auxiliary gap threshold value; the width of the first optical auxiliary line is greater than or equal to a first auxiliary width threshold value; the width of the optical auxiliary line arranged in the gap between the two parts of the main body is less than or equal to a second auxiliary width threshold value; and the gap between the optical auxiliary line close to the dummy pattern and the dummy pattern is greater than or equal to a second auxiliary gap threshold value;

correspondingly, the embodiment of the present invention specifically limits the preprocessing process performed on the original target pattern, as shown in fig. 11, where fig. 11 is a schematic flow chart of another optical proximity correction method provided in the embodiment of the present invention, and as shown in fig. 11, the optical proximity correction method includes the following steps:

s410, obtaining an original target graph, and if the optical auxiliary line of the original target graph does not meet a preset process rule, resetting the optical auxiliary line to meet the preset process rule to form a secondary target graph.

The original target pattern comprises a target pattern for forming a photoetching pattern and an optical auxiliary line for assisting the photoetching pattern to enhance a process window, wherein the optical auxiliary line is small in width and does not influence the exposure pattern after exposure. That is, the optical assist lines do not form a simulated contour. However, if the size of the optical assist line is too large or the position of the optical assist line is too close, the simulated contour is easily distorted, and the exposure pattern is even directly formed.

In this embodiment, the preset process rule includes at least one of the following items, specifically, as shown in fig. 12, fig. 12 is a schematic structural diagram of an optical assist line provided in an embodiment of the present invention. Of the two optical assist lines 113 extending perpendicularly, the gap d4 between the side edge of the first optical assist line 1131 and the end of the second optical assist line 1132 is greater than or equal to the first assist gap threshold; the width d5 of the first optical assist line 1131 is greater than or equal to the first assist width threshold. As shown in fig. 13, fig. 13 is a schematic structural diagram of another optical assist line provided in the embodiment of the present invention. The width d6 of the optical assist line 113 disposed in the gap between the two-part body 11 is less than or equal to the second assist width threshold; and as shown in fig. 14, fig. 14 is a schematic structural diagram of another optical assist line provided in the embodiment of the present invention, and a gap d7 between the optical assist line 113 near the dummy pattern 114 and the dummy pattern 114 is greater than or equal to a second assist gap threshold. In this embodiment, the optical auxiliary lines of the original target pattern are determined according to the preset process rule, and the optical auxiliary lines that do not conform to the preset process rule are reset to form a secondary target pattern.

Optionally, the first auxiliary gap threshold is 20 nm; the first auxiliary width threshold is 10 nm; the second auxiliary width threshold is 40 nm; the second auxiliary gap threshold is 200 nm. When perpendicular to each other, the gap d4 between the first optical assist feature 1131 and the second optical assist feature 1132 is greater than or equal to 20nm, and the width d5 of the first optical assist feature 1131 is greater than or equal to 10 nm; the width d6 of the optical assist line 113 in the gap between the two part bodies 11 is less than or equal to 40 nm; when the gap d7 between the optical assist line 113 and the dummy pattern 114 is greater than or equal to 200nm, the optical assist line will not affect the exposure pattern and will not cause distortion of the simulated contour.

And S420, carrying out optical proximity correction processing on the secondary target graph to obtain a corrected graph.

And S430, acquiring the simulated contour of the original target graph according to the corrected graph.

S440, calculating the deviation between the simulation contour and the original target graph; and judging whether the corrected graph meets the process requirements or not according to the deviation value.

In this embodiment, the size and position of the optical assist line, on which the exposure pattern is not formed, in the original exposure pattern are set to form a secondary target pattern, thereby improving the efficiency of the optical proximity effect correction process and improving the correction accuracy.

On the basis of the above embodiment, the preset process rule in this embodiment may simultaneously satisfy all the specific preset process rules mentioned in steps S210, S310, and S410, so as to improve the accuracy of the corrected graph obtained by passing the secondary target graph through the optical proximity correction model, improve the accuracy of the optical proximity correction, effectively reduce the number of calls of the optical proximity correction model, reduce the optical proximity effect correction cycle, obtain a better correction effect, and improve the qualification rate of the final product.

Based on the same concept, an embodiment of the invention further provides an optical proximity correction apparatus, which can perform optical proximity correction provided by any embodiment of the invention, and fig. 15 is a schematic structural diagram of the optical proximity correction apparatus provided by the embodiment of the invention, as shown in fig. 15, the optical proximity correction apparatus includes:

the secondary processing module 21 is configured to obtain an original target pattern, and pre-process the original target pattern to form a secondary target pattern, so that the secondary target pattern meets a preset process rule;

the correction module 22 is configured to perform optical proximity correction processing on the secondary target pattern to obtain a corrected pattern;

the contour module 23 is used for acquiring a simulated contour of the original target graph according to the corrected graph;

a deviation calculation module 24 for calculating the deviation between the simulated contour and the original target pattern;

and the iteration module 25 is used for circularly calling the correction module and the contour module until the deviation value obtained by the deviation calculation module meets the process requirement.

In the embodiment of the invention, before the optical proximity effect correction is carried out on the target graph, the original target graph is preprocessed, specifically, the original target graph which can influence the accuracy of the exposure graph finally exposed on the film layer is corrected and adjusted in advance to form a secondary target graph, namely, the original target graph which does not meet the preset process rule is adjusted to form the secondary target graph which meets the preset process rule, the optical proximity effect correction is carried out on the secondary target graph to obtain the correction graph, the simulation exposure process is carried out on the correction graph to form the simulation profile, the simulation profile is compared with the original target graph, if the deviation value meets the process requirement, the final accurate correction graph can be determined, and the exposure graph close to the original target graph can be obtained according to the correction graph. Compared with the method for directly correcting the optical proximity effect of the original target graph, the method for correcting the optical proximity effect of the original target graph has the advantages that the original target graph is preprocessed, graph factors causing the deformation of the final simulation outline are eliminated, the simulation outline is ensured to cover the target outline, the problem of serious distortion of an exposure graph is solved, the performance of a finally formed device is improved, and the production yield is improved.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.