Method for obtaining optimal object plane of mask and optical proximity correction method and mask

Abstract

A mask, a method for obtaining an optimal object plane of the mask, and an optical proximity correction method, wherein the method for obtaining an optimal object plane comprises: providing mask information, the mask information comprises a plurality of object plane information and mask patterns, the mask patterns comprise: a main pattern area and an auxiliary pattern area located between the main pattern areas; setting a first auxiliary pattern in the first area; setting a second auxiliary pattern in the second area; setting a plurality of third auxiliary patterns in the third area; performing simulated exposure on the mask pattern to obtain an exposure pattern, comprising: a first exposure pattern, a second exposure pattern, and a third exposure pattern; obtaining an average offset through the first exposure pattern, the second exposure pattern, and the third exposure pattern; obtaining a relationship model between the object plane information and the exposure offset; using the relationship model between the object plane information and the exposure offset, obtaining an optimal object plane through the average offset. The object plane obtained by the method is relatively accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a mask, a method for obtaining an optimal object plane of the mask, and an optical proximity correction method. Background Art

[0002] In semiconductor manufacturing, as the design size continues to shrink, the design size has been close to or smaller than the wavelength of light used in the photolithography process. The diffraction and interference effects of light have become more and more obvious, resulting in serious distortion of the photolithography pattern actually formed relative to the pattern on the mask. Ultimately, the actual pattern formed by photolithography on the silicon wafer becomes different from the designed pattern. This phenomenon is called the Optical Proximity Effect (OPE for short).

[0003] In order to solve the problem of graphic distortion caused by the optical proximity effect, technologies such as Optical Proximity Correction (OPC), Sub-Resolution Assist Features (SRAF), Inverse Lithography Technology (ILT), optimization of light source and mask, and double exposure have emerged.

[0004] In a design, the density of chip graphics is very arbitrary. Both theoretical and experimental results clearly show that the lithography process window of densely distributed graphics is different from that of sparse graphics, which leads to a smaller common process window. The lighting conditions suitable for dense graphics exposure are not suitable for sparse graphics exposure. Adding exposure auxiliary graphics in the design can solve this technical problem.

[0005] Exposure auxiliary graphics are very small graphics that are placed around sparse design graphics to make the sparse graphics look like dense graphics from an optical perspective. The minimum size of these auxiliary graphics must be smaller than the resolution of the photolithography machine. During exposure, they only scatter light and should not form an image on the photoresist. Therefore, exposure auxiliary graphics are also called sub-resolution assistant features (SRAF) or scattering bars.

[0006] In order to add auxiliary graphics to the original design during data processing, the usual practice is to establish a series of rules for inserting auxiliary graphics. This method of adding auxiliary graphics is also called rules-based SRAF. Experience-based auxiliary graphics rely on the experience of designers and have low calculation accuracy. In order to overcome the shortcomings of experience-based auxiliary graphics, inversion lithography technology was proposed and quickly accepted by the industry. However, inversion lithography technology is very complex, especially for the entire chip, and the amount of calculation is huge.

[0007] It can be seen that the correction method of the mask pattern has the disadvantages of low calculation accuracy or huge calculation amount and low efficiency. Summary of the invention

[0008] The technical problem solved by the present invention is to provide a mask, a method for obtaining an optimal object plane of the mask, and a method for optical proximity correction, so as to optimize the correction effect of the mask.

[0009] To solve the above technical problems, the technical solution of the present invention provides a mask, comprising: a substrate; a light-shielding layer located on the substrate, the light-shielding layer having a mask pattern on the surface of the substrate, the mask pattern comprising: a main pattern area; an auxiliary pattern area located between the main pattern areas, the auxiliary pattern area comprising a first area, a second area and a third area, the first area being located between the second area and the third area, and the first area being adjacent to the second area and the third area respectively; a plurality of first auxiliary patterns located in the first area, the plurality of first auxiliary patterns being arranged at equal intervals along a first direction parallel to the surface of the mask pattern; a plurality of second auxiliary patterns located in the second area, the plurality of second auxiliary patterns being arranged at equal intervals along a second direction parallel to the surface of the mask pattern, the second direction being perpendicular to the first direction; a third auxiliary pattern located in the third area, the plurality of third auxiliary patterns being arranged at equal intervals along a second direction parallel to the surface of the mask pattern, the second direction being perpendicular to the first direction.

[0010] Optionally, the first area has a center line axis, and the center line axis runs through the first auxiliary graphics; the second auxiliary graphics and the third auxiliary graphics are arranged symmetrically along the center line axis.

[0011] Optionally, adjacent first auxiliary patterns arranged along the first direction have a third interval, and the third interval is greater than or equal to 200 nanometers.

[0012] Optionally, a distance between the first auxiliary pattern and the second auxiliary pattern farthest from the second region is greater than or equal to 1 μm; a distance between the first auxiliary pattern and the third auxiliary pattern farthest from the third region is greater than or equal to 1 μm.

[0013] The technical solution of the present invention also provides a method for obtaining an optimal object plane of a mask, comprising: providing mask information, the mask information comprising a plurality of object plane information and a mask pattern, the mask pattern comprising: a main pattern area and an auxiliary pattern area located between the main pattern areas, the auxiliary pattern area comprising a first area, a second area and a third area, the first area being located between the second area and the third area, and the first area being adjacent to the second area and the third area respectively; arranging a plurality of first auxiliary patterns in the first area, the plurality of first auxiliary patterns being arranged at equal intervals along a first direction parallel to the surface of the mask pattern; arranging a plurality of second auxiliary patterns in the second area, the plurality of second auxiliary patterns being arranged along a first direction parallel to the surface of the mask pattern; The second direction of the mask pattern surface is arranged at equal intervals, and the second direction is perpendicular to the first direction; a plurality of third auxiliary patterns are set in the third area, and the plurality of third auxiliary patterns are arranged at equal intervals along the second direction parallel to the mask pattern surface, and the second direction is perpendicular to the first direction; the mask pattern is simulated exposed to obtain exposure patterns, and the exposure patterns include: a first exposure pattern, a second exposure pattern and a third exposure pattern; an average offset is obtained through the first exposure pattern, the second exposure pattern and the third exposure pattern; a relationship model between object plane information and exposure offset is obtained; and an optimal object plane is obtained through the average offset using the relationship model between object plane information and exposure offset.

[0014] Optionally, the first distance from the i-th first exposure pattern to the second exposure pattern is Li, and the second distance from the i-th first exposure pattern to the third exposure pattern is Ri, where i is a natural number from 1 to n, and n is the number of the first auxiliary patterns in the first area.

[0015] Optionally, the size range of the Li is greater than or equal to 20 nanometers and less than or equal to 1000 nanometers; the size range of the Ri is greater than or equal to 20 nanometers and less than or equal to 1000 nanometers.

[0016] Optionally, the method for obtaining the average offset includes: obtaining the offsets (Li-Ri) of a plurality of first auxiliary graphics through the first distance and the second distance; averaging the offsets of the plurality of first auxiliary graphics to obtain the average offset

[0017] Optionally, the average offset ranges from 0 nm to 15 nm.

[0018] Optionally, the method for obtaining the optimal object plane according to the average offset and the exposure offset model includes: taking the derivative of the absolute value of the difference between the average offset Mshif and the exposure offset model F(OP) to obtain |F(OP)-M shift |′; when |F(OP)-M shiftWhen |′ is 0, the optimal object plane information OPoptimized is obtained.

[0019] Optionally, the method for obtaining the relationship model includes: using the mask object plane information, performing reflection simulation on the mask pattern with each object plane information to obtain a corresponding reflection pattern; obtaining a number of offsets between the reflection pattern and the corresponding mask pattern; fitting the number of offsets with the mask object plane information to obtain a relationship model PS=F(OP) between the object plane information and the exposure offset, where PS represents the offset and OP represents the mask object plane information.

[0020] The technical solution of the present invention also provides a method for correcting the optical proximity effect according to the optimal object plane of the mask, comprising: providing mask information, the mask information comprising a plurality of object plane information and mask patterns, the mask patterns comprising: a main pattern area and an auxiliary pattern area located between the main pattern areas, the auxiliary pattern area comprising a first area, a second area and a third area, the first area being located between the second area and the third area, and the first area being adjacent to the second area and the third area respectively; obtaining the optimal object plane of the mask according to the mask information, the method for obtaining the optimal object plane of the mask comprising: setting a plurality of first auxiliary patterns in the first area, the plurality of first auxiliary patterns being arranged at equal intervals along a first direction parallel to the surface of the mask pattern; setting a plurality of second auxiliary patterns in the second area, the plurality of second auxiliary patterns being arranged at equal intervals along a first direction parallel to the surface of the mask pattern; The patterns are arranged at equal intervals along a second direction parallel to the surface of the mask pattern, and the second direction is perpendicular to the first direction; a plurality of third auxiliary patterns are arranged at equal intervals along a second direction parallel to the surface of the mask pattern, and the second direction is perpendicular to the first direction; the mask pattern is subjected to simulated exposure to obtain exposure patterns, and the exposure patterns include: a first exposure pattern, a second exposure pattern, and a third exposure pattern; an average offset is obtained through the first exposure pattern, the second exposure pattern, and the third exposure pattern; a relationship model between object plane information and exposure offset is obtained; an optimal object plane is obtained through the average offset using the relationship model between the object plane information and the exposure offset; and an optical proximity effect correction is performed on the mask pattern according to the optimal object plane of the mask.

[0021] Optionally, the first distance from the i-th first exposure pattern to the second exposure pattern is Li, and the second distance from the i-th first exposure pattern to the third exposure pattern is Ri, where i is a natural number from 1 to n, and n is the number of the first auxiliary patterns in the first area.

[0022] Optionally, the size range of the Li is greater than or equal to 20 nanometers and less than or equal to 1000 nanometers; the size range of the Ri is greater than or equal to 20 nanometers and less than or equal to 1000 nanometers.

[0023] Optionally, the method for obtaining the average offset includes: obtaining the offsets (Li-Ri) of a plurality of first auxiliary graphics through the first distance and the second distance; averaging the offsets of the plurality of first auxiliary graphics to obtain the average offset

[0024] Optionally, the average offset ranges from 0 nm to 15 nm.

[0025] Optionally, the method for obtaining the optimal object plane according to the average offset and exposure offset model includes: shif The absolute value of the difference between the exposure offset model F(OP) is derived to obtain |F(OP)-M shift |′; when |F(OP)-M shift When |′ is 0, the optimal object plane information OP is obtained optimized .

[0026] Optionally, the method for obtaining the relationship model includes: using the mask object plane information, performing reflection simulation on the mask pattern with each object plane information to obtain a corresponding reflection pattern; obtaining a number of offsets between the reflection pattern and the corresponding mask pattern; fitting the number of offsets with the mask object plane information to obtain a relationship model PS=F(OP) between the object plane information and the exposure offset, where PS represents the offset and OP represents the mask object plane information.

[0027] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0028] The method for obtaining the optimal object plane of the mask in the technical solution of the present invention is to set a plurality of first auxiliary patterns in the first area, set a plurality of second auxiliary patterns in the second area, and set a plurality of third auxiliary patterns in the third area, simulate the exposure of the mask pattern, obtain the first exposure pattern, the second exposure pattern, and the third exposure pattern, obtain the average offset through the first exposure pattern, the second exposure pattern, and the third exposure pattern, obtain the relationship model between the object plane information and the exposure offset, and then use the relationship model between the object plane information and the exposure offset to obtain the optimal object plane through the average offset. The offset corresponding to the optimal object plane has the smallest deviation from the average offset. The optimal object plane obtained by the method does not require a large amount of numerical calculations, thereby reducing the complexity of the calculation and improving the calculation efficiency; in addition, the optimal object plane obtained by this method does not need to rely on the experience of the designer, and has high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of the structure of a model to be corrected in one embodiment;

[0030] Figure 2 is a schematic top view of a mask in an embodiment of the present invention;

[0031] Figure 3 is a schematic flow chart of a method for obtaining an optimal object plane of a mask in an embodiment of the present invention;

[0032] Figures 4 to 6 is a schematic diagram of a process of obtaining an optimal object plane of a mask in an embodiment of the present invention;

[0033] Figure 7 It is a flow chart of a method for correcting optical proximity effect according to an optimal object plane of a mask in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] As described in the background art, the existing mask pattern correction method has the problems of low calculation accuracy or huge calculation amount and low efficiency. Now, an analysis and explanation is given in combination with a specific model to be corrected.

[0035] Please refer to Figure 1 , Figure 1 1 is a schematic diagram of the structure of a model to be corrected in an embodiment, comprising: a substrate 100; a plurality of composite layers located on the substrate 100, the composite layers comprising a first reflective layer 101 and a second reflective layer 102; a covering layer 103 located on the plurality of composite layers; and an auxiliary pattern 104 located on the covering layer 103.

[0036] In the model to be corrected, each of the first reflection layer 101 and the second reflection layer 102 will reflect the incident light B. In the process of modeling the proximity effect correction of the model to be corrected, in order to save calculation time, a virtual reflection plane AA' is usually used to represent all reflection planes in the real situation. The virtual reflection plane AA' is the object plane. This parameter directly determines the accuracy of the modeling, which requires determining the object plane AA' value.

[0037] At the current stage, the object plane optimization method includes: setting an auxiliary graphic 104 on the model to be corrected, giving the object plane an initial value and a step size, and searching for the best object plane through a limited number of iterations within a certain range, using the root mean square of the model as the cost function, and the formula is: Among them, CD i,resist is the size of the auxiliary figure 104 fitted by the empirical formula, CD i,w is the size of the auxiliary pattern 104 actually measured, and Wi is a given weight value. The smaller the value of the root mean square RMS is, the more suitable the object plane is. However, this method requires a lot of time and computer memory, and is very inefficient. At the same time, the value of the root mean square RMS is relative, and the CD obtained by the empirical formula i,resistThe given weight Wi value is related to the designer's experience, so the resulting object plane is not the optimal solution.

[0038] In order to solve the above problems, the technical solution of the present invention provides a method for obtaining a mask pattern, obtaining an optimal object plane of the mask, and optical proximity correction, by setting a plurality of first auxiliary patterns in the first area, setting a plurality of second auxiliary patterns in the second area, and setting a plurality of third auxiliary patterns in the third area, performing simulated exposure on the mask pattern, obtaining a first exposure pattern, a second exposure pattern, and a third exposure pattern, obtaining an average offset through the first exposure pattern, the second exposure pattern, and the third exposure pattern, obtaining a relationship model between object plane parameters and exposure offset, and then using the relationship model between object plane parameters and exposure offset, obtaining an optimal object plane through an average offset. The offset corresponding to the optimal object plane has the smallest deviation from the average offset. The optimal object plane obtained by the method does not require a large amount of numerical calculations, thereby reducing the complexity of the calculation and improving the calculation efficiency; in addition, the optimal object plane obtained by this method does not need to rely on the experience of the designer, and has a high accuracy.

[0039] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0040] Figure 2 It is a schematic top view of a mask in an embodiment of the present invention.

[0041] Please refer to Figure 2 , comprising a substrate 200; a light-shielding layer located on the substrate 200, the light-shielding layer having a mask pattern on the surface of the substrate, the mask pattern comprising: a main pattern area A (not shown); an auxiliary pattern area located between the main pattern areas A, the auxiliary pattern area comprising a first area I, a second area II and a third area III, the first area I being located between the second area II and the third area III, and the first area I being adjacent to the second area II and the third area III respectively; a plurality of first auxiliary patterns 201 located in the first area I, the plurality of first auxiliary patterns 201 being arranged at equal intervals along a first direction X parallel to the surface of the mask pattern; a plurality of second auxiliary patterns 202 located in the second area II, the plurality of second auxiliary patterns 202 being arranged at equal intervals along a second direction Y parallel to the surface of the mask pattern, the second direction Y being perpendicular to the first direction X; a third auxiliary pattern 203 located in the third area III, the plurality of third auxiliary patterns 203 being arranged at equal intervals along a second direction Y parallel to the surface of the mask pattern, the second direction Y being perpendicular to the first direction X.

[0042] The mask pattern is a pattern made on the mask, and then the pattern on the mask is transferred to the wafer through the exposure process to form a device. The pattern on the main pattern area is a pattern that can be exposed on the wafer, and the pattern of the auxiliary pattern area is used to optically assist the mask structure corresponding to the pattern of the main pattern area on the mask, and the pattern of the auxiliary pattern area cannot be exposed on the wafer.

[0043] The first region I has a center axis B, and the center axis B runs through the first auxiliary graphics 201 ; the second auxiliary graphics 202 and the third auxiliary graphics 203 are arranged symmetrically along the center axis B.

[0044] In this embodiment, adjacent first auxiliary patterns 201 arranged along the first direction X have a third interval N, and the third interval N is greater than or equal to 200 nanometers.

[0045] The first auxiliary pattern 201 arranged within the spacing range facilitates observation of the offset after the subsequent exposure pattern is formed. If the range of the third spacing N is too small, the offset of the first auxiliary pattern 201 after the exposure pattern is formed is not obvious, and measurement cannot be performed, thereby failing to accurately obtain the optimal object plane.

[0046] The distance between the first auxiliary pattern 201 and the adjacent second auxiliary pattern 202 is a first distance l, and the distance between the first auxiliary pattern 201 and the adjacent third auxiliary pattern 203 is a second distance r.

[0047] The first spacing l is in a range of greater than or equal to 20 nanometers and less than or equal to 1000 nanometers; the second spacing r is in a range of greater than or equal to 20 nanometers and less than or equal to 1000 nanometers.

[0048] If the range of the first spacing l is less than 20 nanometers, the subsequent simulated exposure may not be able to form an exposure pattern; if the range of the first spacing l is greater than 1000 nanometers, it is difficult to measure the first spacing after the subsequent exposure pattern is formed, which is not conducive to observing the offset of the exposure pattern.

[0049] In this embodiment, the centerline axis B passes through a plurality of the first auxiliary patterns 201, so that the first spacing and the second spacing are equal. The first spacing and the second spacing are equal, and subsequently the mask pattern is simulated for exposure to obtain an exposure pattern. After the first spacing and the second spacing of the exposure pattern are measured, the offset of the first auxiliary pattern after exposure can be simply calculated, which can simplify the calculation process and improve efficiency.

[0050] In this embodiment, the distance between the first auxiliary pattern 201 and the second auxiliary pattern 202 farthest from the second area II is greater than or equal to 1 μm; the distance between the first auxiliary pattern 201 and the third auxiliary pattern 203 farthest from the third area III is greater than or equal to 1 μm.

[0051] The second zone II and the third zone III are reference systems for the subsequent calculation of the offset of the first auxiliary pattern 201 after exposure, so that the distance between the first auxiliary pattern 201 and the farthest second auxiliary pattern 202 in the second zone II, and the distance between the first auxiliary pattern 201 and the farthest third auxiliary pattern 203 in the third zone III need to meet certain size requirements, that is, greater than or equal to 1 μm, so that the second auxiliary pattern 202 on the second zone II and the third auxiliary pattern 203 on the third zone III can be relatively The first auxiliary pattern 201 will not be offset after exposure, so that the offset of the first auxiliary pattern 201 after exposure can be accurately calculated.

[0052] Figure 3 It is a schematic flow chart of a method for obtaining an optimal object plane of a mask in an embodiment of the present invention.

[0053] Please refer to Figure 3 , the method for obtaining the optimal object plane of the mask includes:

[0054] S1: Providing mask information, wherein the mask information includes a plurality of object plane information and a mask pattern, wherein the mask pattern includes: a main pattern area and an auxiliary pattern area located between the main pattern areas, wherein the auxiliary pattern area includes a first area, a second area, and a third area, wherein the first area is located between the second area and the third area, and the first area is adjacent to the second area and the third area respectively;

[0055] S2: Arranging a plurality of first auxiliary patterns in the first area, wherein the plurality of first auxiliary patterns are arranged at equal intervals along a first direction parallel to the surface of the mask pattern;

[0056] S3: Arranging a plurality of second auxiliary patterns in the second area, wherein the plurality of second auxiliary patterns are arranged at equal intervals along a second direction parallel to the surface of the mask pattern, and the second direction is perpendicular to the first direction;

[0057] S4: Arranging a plurality of third auxiliary patterns in the third area, wherein the plurality of third auxiliary patterns are arranged at equal intervals along a second direction parallel to the surface of the mask pattern, and the second direction is perpendicular to the first direction;

[0058] S5: performing simulated exposure on the mask pattern to obtain exposure patterns, wherein the exposure patterns include: a first exposure pattern, a second exposure pattern, and a third exposure pattern;

[0059] S6: obtaining an average offset through the first exposure pattern, the second exposure pattern and the third exposure pattern;

[0060] S7: Obtaining a relationship model between object plane parameters and exposure offset;

[0061] S8: Using the relationship model between the object plane parameters and the exposure offset, the optimal object plane is obtained by averaging the offset.

[0062] The method is used to obtain the optimal object plane without requiring a large amount of numerical calculations, thereby reducing the complexity of the calculations and improving the calculation efficiency. In addition, the method is used to obtain the optimal object plane without relying on the experience of the designer and has a high accuracy.

[0063] Figures 4 to 6 It is a schematic diagram of the process of obtaining the optimal object plane of the mask in an embodiment of the present invention.

[0064] Please refer to Figure 4 and Figure 5 , Figure 4 and Figure 5 is a schematic diagram of the process from S1 to S4, Figure 4 for Figure 5 A top view of Figure 5 for Figure 4 A cross-sectional schematic diagram along the section line MM' direction provides mask information, wherein the mask information includes a plurality of object plane information OP and a mask pattern, wherein the mask pattern includes: a main pattern area A and an auxiliary pattern area located between the main pattern areas A, wherein the auxiliary pattern area includes a first region I, a second region II and a third region III, wherein the first region I is located between the second region II and the third region III, and the first region I is adjacent to the second region II and the third region III, respectively.

[0065] The mask information is various parameters of the mask that needs to be exposed to form a pattern on the wafer surface. The structure of the mask includes a substrate 200, a plurality of reflective layers (not shown) located on the substrate 200, and a light-shielding layer located on the plurality of reflective layers, and the light-shielding layer has a mask pattern on the substrate surface. The mask information provides the parameters required for the subsequent process of obtaining the optimal object plane of the mask.

[0066] The object plane information OP includes: the relative distances between the reflective layers on the substrate 200 and the objective lens in the exposure system; the object plane is a virtual plane in the OPC model that can represent the actual reflection conditions of all reflective planes, and the accuracy of the object plane determines the accuracy of the OPC model.

[0067] The mask pattern is the aforementioned Figure 2 For the specific structure of the mask pattern, please refer to Figure 2, I will not go into details here.

[0068] Please continue to refer to Figure 4 and Figure 5 , obtain the relationship model F(OP) between the object plane information OP and the exposure offset PS.

[0069] The relationship model F(OP) between the object plane information OP and the exposure offset PS is: when the reflection simulation of the mask pattern is performed using different reflection layers as the object plane, the offset of the obtained reflection pattern to the corresponding mask pattern is different. Subsequently, the optimal object plane can be obtained by averaging the offset according to the relationship model F(OP) between the object plane information OP and the exposure offset PS.

[0070] The method for obtaining the relationship model F(OP) includes: using the mask object plane information OP, performing reflection simulation on the mask pattern with each object plane information OP to obtain a corresponding reflection pattern (not shown); obtaining a number of offsets PS between the reflection pattern and the corresponding mask pattern; fitting the number of offsets PS with the mask object plane information OP to obtain a relationship model PS=F(OP) between the object plane information OP and the exposure offset PS, where PS represents the offset and OP represents the mask object plane information.

[0071] Please continue to refer to Figure 4 and Figure 5 A plurality of first auxiliary patterns 201 are arranged in the first region I, and the plurality of first auxiliary patterns 201 are arranged at equal intervals along a first direction X parallel to the surface of the mask pattern.

[0072] A plurality of second auxiliary patterns 202 are arranged in the second region II. The plurality of second auxiliary patterns 202 are arranged at equal intervals along a second direction Y parallel to the surface of the mask pattern. The second direction Y is perpendicular to the first direction X.

[0073] A plurality of third auxiliary patterns 203 are arranged in the third region III. The plurality of third auxiliary patterns 203 are arranged at equal intervals along a second direction Y parallel to the surface of the mask pattern. The second direction Y is perpendicular to the first direction X.

[0074] The first auxiliary pattern 201 is used to form a first exposure pattern later; the second auxiliary pattern 202 is used to form a second exposure pattern later; the third auxiliary pattern 203 is used to form a third exposure pattern later. The second exposure pattern and the third exposure pattern are used as references for calculating the amount of displacement of the first exposure pattern relative to the first auxiliary pattern.

[0075] Please refer to Figure 6 , Figure 6 For Figure 4Based on the schematic diagram, Figure 6 It is a schematic diagram of steps S5 to S8 , performing simulated exposure on the mask pattern to obtain exposure patterns, the exposure patterns including: a first exposure pattern 301 , a second exposure pattern 302 and a third exposure pattern 303 .

[0076] The first exposure pattern 301 is an exposure pattern of the first auxiliary pattern 201 ; the second exposure pattern 302 is an exposure pattern of the second auxiliary pattern 202 ; and the third exposure pattern 303 is an exposure pattern of the third auxiliary pattern 203 .

[0077] Please continue to refer to Figure 6 , the average offset M is obtained by the first exposure pattern 301, the second exposure pattern 302 and the third exposure pattern 303 shift .

[0078] The first distance from the i-th first exposure pattern 301 to the second exposure pattern 302 is Li, and the second distance from the i-th first exposure pattern 301 to the third exposure pattern 303 is Ri, where i is a natural number from 1 to n, and n is the number of the first auxiliary patterns 201 in the first area I.

[0079] The size range of the Li is greater than or equal to 20 nanometers and less than or equal to 1000 nanometers; the size range of the Ri is greater than or equal to 20 nanometers and less than or equal to 1000 nanometers.

[0080] Get the average offset M shift The method comprises: obtaining the offsets (Li-Ri) of a plurality of first auxiliary graphics 201 through a first distance Li and a second distance Ri; averaging the offsets of the plurality of first auxiliary graphics 201 to obtain the average offset

[0081] The range of the average offset is: 0 nanometers to 15 nanometers. If the range of the average offset is too large, the optimal object plane obtained by the average offset is not accurate enough, and the accuracy of the model is thus corrected.

[0082] Next, the relationship model PS=F(OP) between the object plane information OP and the exposure offset PS is used, and the average offset M shift Get the optimal object plane OP optimized .

[0083] According to the average offset M shift Get the optimal object plane OP with the exposure offset model F(OP) optimized The method comprises: shift The absolute value of the difference between the exposure offset model F(OP) is derived to obtain |F(OP)-Mshift |′; when |F(OP)-M shift When |′ is 0, the optimal object plane information OP is obtained optimized .

[0084] When |F(OP)-M shift When |′ is 0, the optimal object plane information OP is obtained optimized The graphic offset and the average offset M shift closest to the optimal object plane information OP optimized The optimal object plane information OP can represent the reflection plane of the object plane of the mask, so as to simulate the reflection of each object plane. optimized After being substituted into the OPC model, the correction effect of the OPC model on the mask pattern is more accurate, thereby reducing the number of iterations in the OPC process and improving the working efficiency of the OPC.

[0085] Figure 7 It is a flow chart of a method for correcting optical proximity effect according to an optimal object plane of a mask in an embodiment of the present invention.

[0086] Please refer to Figure 7 The method for correcting the optical proximity effect according to the optimal object plane of the mask includes:

[0087] S1: Providing mask information, wherein the mask information includes a plurality of object plane information and a mask pattern, wherein the mask pattern includes: a main pattern area and an auxiliary pattern area located between the main pattern areas, wherein the auxiliary pattern area includes a first area, a second area, and a third area, wherein the first area is located between the second area and the third area, and the first area is adjacent to the second area and the third area respectively;

[0088] S2: Obtaining the optimal object plane of the mask according to the mask information, the method for obtaining the optimal object plane of the mask includes: setting a plurality of first auxiliary graphics in a first area, the plurality of first auxiliary graphics are arranged at equal intervals along a first direction parallel to the surface of the mask pattern; setting a plurality of second auxiliary graphics in a second area, the plurality of second auxiliary graphics are arranged at equal intervals along a second direction parallel to the surface of the mask pattern, and the second direction is perpendicular to the first direction; setting a plurality of third auxiliary graphics in a third area, the plurality of third auxiliary graphics are arranged at equal intervals along a second direction parallel to the surface of the mask pattern, and the second direction is perpendicular to the first direction; performing simulated exposure on the mask pattern to obtain exposure graphics, the exposure graphics including: a first exposure graphic, a second exposure graphic and a third exposure graphic; obtaining an average offset through the first exposure graphic, the second exposure graphic and the third exposure graphic; obtaining a relationship model between the object plane information and the exposure offset; using the relationship model between the object plane information and the exposure offset, obtaining the optimal object plane through the average offset;

[0089] S3: performing optical proximity effect correction on the mask pattern according to the mask optimal object plane.

[0090] In this embodiment, the mask information is as follows: Figure 4 and Figure 5 The above is not repeated here.

[0091] In this embodiment, in the method for obtaining the optimal object plane of the mask according to the mask information, a relationship model F(OP) between the object plane information OP and the exposure offset PS is obtained; a plurality of first auxiliary graphics are arranged in a first direction parallel to the surface of the mask graphic, and are arranged at equal intervals; a plurality of second auxiliary graphics are arranged in a second region, and the plurality of second auxiliary graphics are arranged in a second direction parallel to the surface of the mask graphic, and the second direction is perpendicular to the first direction; a plurality of third auxiliary graphics are arranged in a third region, and the plurality of third auxiliary graphics are arranged in a second direction parallel to the surface of the mask graphic, and the second direction is perpendicular to the first direction. For the relationship model F(OP) for obtaining the object plane information OP and the exposure offset PS, and the setting and arrangement of the first auxiliary graphics, the second auxiliary graphics and the third auxiliary graphics, please refer to Figure 4 and Figure 5 , I will not go into details here.

[0092] In this embodiment, in the method for obtaining the optimal object plane of the mask according to the mask information, the mask pattern is simulated exposed to obtain exposure patterns, and the exposure patterns include: a first exposure pattern, a second exposure pattern, and a third exposure pattern; an average offset is obtained through the first exposure pattern, the second exposure pattern, and the third exposure pattern; a relationship model between the object plane information and the exposure offset is obtained; and the relationship model between the object plane information and the exposure offset is used to obtain the optimal object plane through the average offset. For the specific process of obtaining the exposure pattern, obtaining the average offset, obtaining the relationship model between the object plane information and the exposure offset, and obtaining the optimal object plane through the average offset, please refer to Figure 6 , I will not go into details here.

[0093] Getting the best object plane information OP optimized Afterwards, the optimal object plane information OP optimized Substituting into the OPC model, the optical proximity effect correction is performed, and the optical proximity effect correction has a good effect and high efficiency.

[0094] So far, in the method for obtaining the optimal object plane of the mask according to the technical solution of the present invention, a plurality of first auxiliary patterns are set in the first area, a plurality of second auxiliary patterns are set in the second area, and a plurality of third auxiliary patterns are set in the third area, and the mask pattern is simulated exposed to obtain the first exposure pattern, the second exposure pattern and the third exposure pattern, and the average offset is obtained through the first exposure pattern, the second exposure pattern and the third exposure pattern, and the relationship model between the object plane information and the exposure offset is obtained, and then the relationship model between the object plane information and the exposure offset is used to obtain the optimal object plane through the average offset. The offset corresponding to the optimal object plane has the smallest deviation from the average offset. The optimal object plane is obtained by the method without a large amount of numerical calculation, thereby reducing the complexity of the calculation and improving the calculation efficiency; in addition, the optimal object plane obtained by this method does not need to rely on the experience of the designer, and has high accuracy.

[0095] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A mask, characterized in that: include: substrate; A light shielding layer located on the substrate, wherein the light shielding layer has a mask pattern on the surface of the substrate, and the mask pattern includes: a main pattern area; An auxiliary graphic area located between the main graphic areas, the auxiliary graphic area comprising a first area, a second area and a third area, the first area being located between the second area and the third area, and the first area being adjacent to the second area and the third area respectively; A plurality of first auxiliary patterns located in the first area, the plurality of first auxiliary patterns being arranged at equal intervals along a first direction parallel to the surface of the mask pattern, the first area having a center line axis, the center line axis passing through the plurality of first auxiliary patterns; A plurality of second auxiliary patterns located in the second area, the plurality of second auxiliary patterns being arranged at equal intervals along a second direction parallel to the surface of the mask pattern, the second direction being perpendicular to the first direction; A third auxiliary pattern located in the third area, wherein the plurality of third auxiliary patterns are arranged at equal intervals along a second direction parallel to the surface of the mask pattern, wherein the second direction is perpendicular to the first direction, and the plurality of second auxiliary patterns and the plurality of third auxiliary patterns are arranged symmetrically along the center line axis.

2. The mask according to claim 1, characterized in that: Adjacent first auxiliary patterns arranged along the first direction have a third interval, and the range of the third interval is greater than or equal to 200 nanometers.

3. The mask according to claim 1, wherein: The distance between the first auxiliary pattern and the second auxiliary pattern farthest from the second region is greater than or equal to 1 μm; the distance between the first auxiliary pattern and the third auxiliary pattern farthest from the third region is greater than or equal to 1 μm.

4. A method for obtaining an optimal object plane of a mask, characterized in that: include: Providing mask information, the mask information including a plurality of object plane information and a mask pattern, the mask pattern including: a main pattern area and an auxiliary pattern area located between the main pattern areas, the auxiliary pattern area including a first area, a second area and a third area, the first area being located between the second area and the third area, and the first area being adjacent to the second area and the third area respectively; A plurality of first auxiliary patterns are arranged in the first area, and the plurality of first auxiliary patterns are arranged at equal intervals along a first direction parallel to the surface of the mask pattern; A plurality of second auxiliary patterns are arranged in the second area, and the plurality of second auxiliary patterns are arranged at equal intervals along a second direction parallel to the surface of the mask pattern, and the second direction is perpendicular to the first direction; A plurality of third auxiliary patterns are arranged in the third area, and the plurality of third auxiliary patterns are arranged at equal intervals along a second direction parallel to the surface of the mask pattern, and the second direction is perpendicular to the first direction; Performing simulated exposure on the mask pattern to obtain exposure patterns, the exposure patterns comprising: a first exposure pattern, a second exposure pattern and a third exposure pattern, the first exposure pattern is an exposure pattern of a first auxiliary pattern, the second exposure pattern is an exposure pattern of a second auxiliary pattern, and the third exposure pattern is an exposure pattern of a third auxiliary pattern; The average offset is obtained by using the first exposure pattern, the second exposure pattern and the third exposure pattern. The Li is a first distance from the i-th first exposure pattern to the second exposure pattern, the Ri is a second distance from the i-th first exposure pattern to the third exposure pattern, i is a natural number from 1 to n, and n is the number of the first auxiliary patterns in the first area; Obtaining a relationship model between object plane information and exposure offset, wherein the relationship model PS=F(OP), wherein PS represents the offset, and OP represents the mask object plane information; The relationship model between object plane information and exposure offset is adopted, and the optimal object plane is obtained by averaging the offset.

5. The method for obtaining the optimal object plane of a mask according to claim 4, characterized in that: The size range of Li is greater than or equal to 20 nanometers and less than or equal to 1000 nanometers; the size range of Ri is greater than or equal to 20 nanometers and less than or equal to 1000 nanometers.

6. The method for obtaining the optimal object plane of a mask according to claim 4, characterized in that: The method for obtaining the average offset includes: obtaining the offsets (Li-Ri) of a plurality of first auxiliary graphics through the first distance and the second distance; calculating the average value of the offsets of the plurality of first auxiliary graphics to obtain the average offset 7. The method for obtaining the optimal object plane of a mask according to claim 6, characterized in that: The average offset ranges from 0 nm to 15 nm.

8. The method for obtaining the optimal object plane of a mask according to claim 4, characterized in that: The method for obtaining the optimal object plane according to the average offset and exposure offset model includes: shif The absolute value of the difference between the exposure offset model F(OP) is derived to obtain |F(OP)-M shift |′; when |F(OP)-M shift When |′ is 0, the optimal object plane information OP is obtained optimized .

9. The method for obtaining the optimal object plane of a mask according to claim 4, characterized in that: The method for obtaining the relationship model includes: using the mask object plane information, performing reflection simulation on the mask pattern with each object plane information to obtain a corresponding reflection pattern; obtaining a number of offsets between the reflection pattern and the corresponding mask pattern; fitting the several offsets with the mask object plane information to obtain a relationship model PS=F(OP) between the object plane information and the exposure offset, where PS represents the offset and OP represents the mask object plane information.

10. A method for correcting optical proximity effect based on the optimal object plane of a mask, characterized in that: include: Providing mask information, the mask information including a plurality of object plane information and a mask pattern, the mask pattern including: a main pattern area and an auxiliary pattern area located between the main pattern areas, the auxiliary pattern area including a first area, a second area and a third area, the first area being located between the second area and the third area, and the first area being adjacent to the second area and the third area respectively; The optimal object plane of the mask is obtained according to the mask information. The method for obtaining the optimal object plane of the mask includes: A plurality of first auxiliary patterns are arranged in the first area, and the plurality of first auxiliary patterns are arranged at equal intervals along a first direction parallel to the surface of the mask pattern; A plurality of second auxiliary patterns are arranged in the second area, and the plurality of second auxiliary patterns are arranged at equal intervals along a second direction parallel to the surface of the mask pattern, and the second direction is perpendicular to the first direction; A plurality of third auxiliary patterns are arranged in the third area, and the plurality of third auxiliary patterns are arranged at equal intervals along a second direction parallel to the surface of the mask pattern, and the second direction is perpendicular to the first direction; Performing simulated exposure on the mask pattern to obtain exposure patterns, the exposure patterns comprising: a first exposure pattern, a second exposure pattern and a third exposure pattern, the first exposure pattern is an exposure pattern of a first auxiliary pattern, the second exposure pattern is an exposure pattern of a second auxiliary pattern, and the third exposure pattern is an exposure pattern of a third auxiliary pattern; The average offset is obtained by using the first exposure pattern, the second exposure pattern and the third exposure pattern. The Li is a first distance from the i-th first exposure pattern to the second exposure pattern, the Ri is a second distance from the i-th first exposure pattern to the third exposure pattern, i is a natural number from 1 to n, and n is the number of the first auxiliary patterns in the first area; Obtaining a relationship model between object plane information and exposure offset, wherein the relationship model PS=F(OP), wherein PS represents the offset, and OP represents the mask object plane information; The relationship model between object plane information and exposure offset is adopted to obtain the optimal object plane by averaging the offset; The optical proximity effect correction is performed on the mask pattern according to the optimal object plane of the mask.

11. The method for correcting optical proximity effect according to the optimal object plane of the mask according to claim 10, characterized in that: The size range of Li is greater than or equal to 20 nanometers and less than or equal to 1000 nanometers; the size range of Ri is greater than or equal to 20 nanometers and less than or equal to 1000 nanometers.

12. The method for correcting optical proximity effect according to the optimal object plane of the mask according to claim 10, characterized in that: The method for obtaining the average offset includes: obtaining the offsets (Li-Ri) of a plurality of first auxiliary graphics through the first distance and the second distance; calculating the average value of the offsets of the plurality of first auxiliary graphics to obtain the average offset 13. The method for correcting optical proximity effect according to the optimal object plane of the mask according to claim 12, characterized in that: The average offset ranges from 0 nm to 15 nm.

14. The method for correcting optical proximity effect according to the optimal object plane of the mask according to claim 10, characterized in that: The method for obtaining the optimal object plane according to the average offset and exposure offset model includes: shif The absolute value of the difference between the exposure offset model F(OP) is derived to obtain |F(OP)-M shift |′; when |F(OP)-M shift When |′ is 0, the optimal object plane information OP is obtained optimized .

15. The method for correcting optical proximity effect according to the optimal object plane of the mask according to claim 10, characterized in that: The method for obtaining the relationship model includes: using the mask object plane information, performing reflection simulation on the mask pattern with each object plane information to obtain a corresponding reflection pattern; obtaining a number of offsets between the reflection pattern and the corresponding mask pattern; fitting the several offsets with the mask object plane information to obtain a relationship model PS=F(OP) between the object plane information and the exposure offset, where PS represents the offset and OP represents the mask object plane information.

Images