CN114326290A - Optical proximity correction method - Google Patents
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Abstract
An optical proximity correction method comprising: providing an initial graph, wherein the initial graph is provided with a first part and a second part which are vertical, and the first part is provided with a first outer edge and a first inner edge which are parallel; obtaining an optimal segment length range according to the exposure parameters; acquiring a plurality of sampling lengths according to the sampling step length within the optimal segmentation length range; performing segmentation processing on the first outer edge and the first inner edge to obtain a first edge section, a second edge section and a plurality of middle sections; carrying out full-array combination assignment on the first edge section, the second edge section and the middle section by adopting a plurality of sampling lengths to obtain a plurality of initial segmentation graphs corresponding to the initial graphs; acquiring a corresponding first exposure graph; acquiring a placement edge error corresponding to each line segment; and acquiring a segmentation graph according to each placement edge error. The initial layout is subjected to a plurality of segmentation schemes, and the optimal segmentation collocation of the initial layout is obtained through final screening, so that the problem that the end of the graph line after correction exposure shrinks seriously is solved.
Description
Technical Field
The invention relates to the technical field of semiconductor manufacturing, in particular to an optical proximity correction method.
Background
The photoetching technology is a vital technology in the semiconductor manufacturing technology, and can realize the transfer of a pattern from a mask to the surface of a silicon wafer to form a semiconductor product meeting the design requirement. The photolithography process includes an exposure step, a development step performed after the exposure step, and an etching step after the development step. In the exposure step, light irradiates on a silicon wafer coated with photoresist through a light-transmitting area in a mask plate, and the photoresist undergoes a chemical reaction under the irradiation of the light; in the developing step, photoetching patterns are formed by utilizing the different dissolution degrees of photosensitive and non-photosensitive photoresist to a developer, so that the mask pattern is transferred to the photoresist; in the etching step, the silicon wafer is etched based on the photoetching pattern formed by the photoetching adhesive layer, and the pattern of the mask is further transferred to the silicon wafer.
In semiconductor manufacturing, as the design size is continuously reduced and the design size is closer to the limit of the lithography imaging system, the diffraction Effect of light becomes more and more obvious, which causes the Optical image degradation of the design pattern, the actual formed lithography pattern is seriously distorted relative to the pattern on the mask, and the actual pattern and the design pattern formed by lithography on the silicon wafer are different, and this phenomenon is called Optical Proximity Effect (OPE).
In order to correct for Optical Proximity effects, an Optical Proximity Correction (OPC) is generated. The core idea of optical proximity correction is to establish an optical proximity correction model based on consideration of counteracting optical proximity effect, and design a photomask pattern according to the optical proximity correction model, so that although the optical proximity effect occurs to the photomask pattern corresponding to the photoetched photoetching pattern, the counteraction of the phenomenon is considered when the photomask pattern is designed according to the optical proximity correction model, and therefore, the photoetched photoetching pattern is close to a target pattern actually expected by a user.
However, there are still many problems in the optical proximity correction in the prior art.
Disclosure of Invention
The invention provides an optical proximity correction method, which can effectively improve the final optical proximity correction effect.
In order to solve the above problem, an embodiment of the present invention provides an optical proximity correction method, including: providing an initial pattern, the initial pattern having a first portion and a second portion that are perpendicular to each other, the first portion having a first outer edge and a first inner edge that are parallel to each other, and connecting the first outer edge with a first end edge of the first inner edge, the second portion having a second outer edge and a second inner edge that are parallel to each other, and connecting the second outer edge with a second end edge of the second inner edge, the first inner edge being perpendicularly connected to the second inner edge, the first outer edge being perpendicularly connected to the second outer edge, the first outer edge having a first length dimension, the first inner edge having a second length dimension, and the first length dimension being greater than the second length dimension; obtaining an optimal segment length range according to the exposure parameters; acquiring a plurality of sampling lengths within the optimal segmentation length range according to sampling step length, wherein the minimum difference value among different sampling lengths is the sampling step length; the first outer edge and the first inner edge are subjected to segmentation processing to obtain a plurality of first edge sections, a plurality of second edge sections and a plurality of middle sections, the first outer edge comprises the first edge sections, the second edge sections and a plurality of middle sections positioned between the first edge sections and the second edge sections, the first inner edge comprises the first edge sections, the second edge sections and a plurality of middle sections positioned between the first edge sections and the second edge sections, and the number of the middle sections of the first outer edge is greater than that of the middle sections of the first inner edge; adopting a plurality of sampling lengths to carry out full-permutation combination assignment on the lengths of the first edge section, the second edge section and the middle section, and obtaining a plurality of initial segmentation graphs corresponding to the initial graphs; carrying out a plurality of times of first optical proximity correction and exposure processing on each initial segmentation graph to obtain a corresponding first exposure graph; according to each initial segmentation graph and the corresponding first exposure graph, acquiring an end placement edge error corresponding to the first end edge, a first edge placement error of the first edge section, a second placement edge error of the second edge section and a middle placement edge error of the middle section; and acquiring a segmentation graph from the plurality of initial segmentation graphs according to each corresponding end placement edge error, first edge placement error, second placement edge error and a plurality of middle placement edge errors.
Optionally, the exposure parameters include: numerical aperture NA, exposure wavelength λ, and light source parameter σ.
Optionally, the method for obtaining the optimal segment length range according to the exposure parameters includes: acquiring a Nyquist value according to the numerical aperture NA, the exposure wavelength lambda and the light source parameter sigma, wherein:
the optimal segment length range is: [1.5Nyquist, 3Nyquist ].
Optionally, the range of the sampling step length is: 4 to 6 nanometers.
Optionally, the method for obtaining the segmentation graph from the plurality of initial segmentation graphs according to each corresponding end placement edge error, first edge placement error, second placement edge error, and a plurality of middle placement edge errors includes: obtaining the ratio of each corresponding end placement edge error, first edge placement error, second edge placement error and a plurality of middle placement edge errors; and taking the initial segmentation graph corresponding to the minimum matching value as the segmentation graph.
Optionally, the method for obtaining the ratio of each corresponding end placement edge error, first edge placement error, second placement edge error, and a plurality of middle placement edge errors includes: obtaining the proportion value of each corresponding end placement edge error, first edge placement error, second placement edge error and a plurality of middle placement edge errors according to a Root Mean Square (RMS) formula, wherein:
wherein, EPEiPlacing an edge error for the end, a first edge placement error, a second edge placement errorTwo placed edge errors or several intermediate placed edge errors, WiWeights corresponding to the end placement edge errors, the first edge placement error, the second placement edge error, or the plurality of intermediate placement edge errors.
Optionally, after the initial segmentation graph corresponding to the minimum matching value is used as the segmentation graph, the method further includes: and updating the optical proximity correction method to an optical proximity correction model library.
Optionally, after the initial segmentation graph corresponding to the minimum matching value is used as the segmentation graph, the method further includes: and carrying out a plurality of times of second optical proximity correction and exposure processing on the segmentation graph to obtain a second exposure graph.
Optionally, the number of the middle sections of the first outer edge is 2; the number of the middle sections of the first inner edge is 1.
Compared with the prior art, the technical scheme of the invention has the following advantages:
in the optical proximity correction method of the technical scheme of the invention, an optimal segment length range is obtained through exposure parameters, a plurality of sampling lengths are obtained within the optimal segment length range according to sampling step length, and the minimum difference value among different sampling lengths is the sampling step. The method comprises the steps that a plurality of first edge sections, a plurality of second edge sections and a plurality of middle sections are obtained by conducting segmentation processing on a first outer edge and a first inner edge, wherein the first outer edge comprises the first edge sections, the second edge sections and the middle sections located between the first edge sections and the second edge sections, and the first inner edge comprises the first edge sections, the second edge sections and the middle sections located between the first edge sections and the second edge sections; adopting a plurality of sampling lengths to carry out full-permutation combination assignment on the lengths of the first edge section, the second edge section and the middle section to obtain a plurality of initial segmentation graphs corresponding to the initial graphs; carrying out a plurality of times of first optical proximity correction and exposure processing on each initial segmentation graph to obtain a corresponding first exposure graph; according to each initial segmentation graph and the corresponding first exposure graph, acquiring an end placement edge error corresponding to the first end edge, a first edge placement error of the first edge section, a second placement edge error of the second edge section and a middle placement edge error of the middle section; and acquiring a segmentation graph from the plurality of initial segmentation graphs according to each corresponding end placement edge error, first edge placement error, second placement edge error and a plurality of middle placement edge errors. On the premise of mask manufacturing capability, exposure parameters and the characteristics of the graph are comprehensively considered, a plurality of segmentation schemes are carried out on the initial graph, the optimal segmentation collocation of the initial graph is obtained through final screening, the conflict between outward extension and MRC when the graph line end is subjected to optical proximity correction is effectively avoided, the edge placement error at the graph line end is effectively reduced, and the problem that the graph line end is seriously shrunk after correction exposure is further solved.
Further, after the initial segmentation graph corresponding to the minimum matching value is used as the segmentation graph, the method further includes: and updating the optical proximity correction method to an optical proximity correction model library. The optical proximity correction method is updated to the optical proximity correction model library, so that the optical proximity correction method can be directly adopted when the same type of graphic processing is carried out subsequently.
Drawings
FIGS. 1 and 2 are schematic structural diagrams of steps of an optical proximity correction method;
FIG. 3 is a flowchart of an optical proximity correction method according to an embodiment of the present invention;
fig. 4 to 9 are schematic structural diagrams of steps of an optical proximity correction method according to an embodiment of the present invention.
Detailed Description
As described in the background, there are still problems with optical proximity correction in the prior art. The following detailed description will be made in conjunction with the accompanying drawings.
Please refer to fig. 1, provide initial figure 100, initial figure 100 has mutually perpendicular's first portion 100a and second portion 100b, first portion 100a has mutually parallel first outer edge L1 and first interior limit L2, and connects first outer edge L1 with first end limit E0 of first interior limit L2, second portion 100b has mutually parallel second outer edge and second interior limit, and connects the second outer edge with the second end limit (not marked) of second interior limit, first interior limit L2 with the perpendicular connection of second interior limit, first outer edge L1 with the perpendicular connection of second outer edge, first outer edge has first length size, first interior limit has second length size, and first length size is greater than the second length size.
Referring to fig. 2, the initial pattern 100 is subjected to optical proximity correction and exposure for several times to obtain an exposed pattern 101.
Since the existing model-based optical proximity correction is an automatic correction method with software control, which usually avoids the final dimension being too small due to excessive correction, and the too small dimension is a challenge for reticle fabrication, in the model-based optical proximity correction, the minimum pattern dimension and the minimum pattern pitch are set, and once the pattern reaches the critical dimension during the optical proximity correction, the pattern edge stops moving to avoid violating the minimum value set by the optical proximity correction, which is called the reticle dimension limit (Mask Rule Constraint MRC) in the model-based optical proximity correction.
With the reduction of the size of the device and the increase of the complexity of the layout, when the optical proximity correction model library corrects the layout globally, when a special graph with a right angle and two adjacent Edge lengths inconsistent is processed, the global optical proximity correction cannot be segmented well, and due to the limitation of MRC, the line end of the graph cannot extend outwards to reduce an Edge correction Error (Edge Placement Error EPE), so that the EPE is too large, and the line end of the graph after correction exposure shrinks seriously (as shown in part a in fig. 2).
On the basis, the invention provides an optical proximity correction method, on the premise of mask manufacturing capability, exposure parameters and the characteristics of graphs are comprehensively considered, a plurality of segmentation schemes are carried out on the initial layout, the optimal segmentation collocation of the initial layout is obtained through final screening, the conflict between outward extension and MRC when the line end of the graph is subjected to optical proximity correction is effectively avoided, the edge placement error at the line end of the graph is effectively reduced, and the problem that the line end of the graph after correction exposure is seriously shrunk is further solved.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
FIG. 3 is a flowchart of an optical proximity correction method according to an embodiment of the present invention, including:
step S101, providing an initial pattern, wherein the initial pattern has a first portion and a second portion that are perpendicular to each other, the first portion has a first outer edge and a first inner edge that are parallel to each other, and a first end edge that connects the first outer edge and the first inner edge, the second portion has a second outer edge and a second inner edge that are parallel to each other, and a second end edge that connects the second outer edge and the second inner edge, the first inner edge is perpendicularly connected to the second inner edge, the first outer edge is perpendicularly connected to the second outer edge, the first outer edge has a first length dimension, the first inner edge has a second length dimension, and the first length dimension is greater than the second length dimension;
step S102, obtaining the optimal segment length range according to the exposure parameters;
step S103, acquiring a plurality of sampling lengths according to sampling step lengths within the optimal segment length range, wherein the minimum difference value among different sampling lengths is the sampling step length;
step S104, the first outer edge and the first inner edge are subjected to segmentation processing to obtain a plurality of first edge sections, a plurality of second edge sections and a plurality of middle sections, the first outer edge comprises the first edge sections, the second edge sections and a plurality of middle sections positioned between the first edge sections and the second edge sections, the first inner edge comprises the first edge sections, the second edge sections and a plurality of middle sections positioned between the first edge sections and the second edge sections, and the number of the middle sections of the first outer edge is greater than that of the middle sections of the first inner edge;
step S105, carrying out full-permutation combination assignment on the lengths of the first edge section, the second edge section and the middle section by adopting a plurality of sampling lengths to obtain a plurality of initial segmentation graphs corresponding to the initial graphs;
step S106, carrying out a plurality of times of first optical proximity correction and exposure processing on each initial segmentation graph to obtain a corresponding first exposure graph;
step S107, obtaining an end placement edge error corresponding to the first end edge, a first edge placement error of the first edge segment, a second placement edge error of the second edge segment, and a middle placement edge error of the middle segment according to each initial segmentation graph and the corresponding first exposure graph;
and step S108, acquiring a segmentation graph from the initial segmentation graphs according to each corresponding end placement edge error, first edge placement error, second edge placement error and a plurality of middle placement edge errors.
The steps of the optical proximity correction method are described in detail below with reference to the accompanying drawings.
Fig. 4 to 9 are schematic structural diagrams of steps of an optical proximity correction method according to an embodiment of the present invention.
Please refer to fig. 4, which provides an initial graph 200, the initial graph 200 has a first portion 200a and a second portion 200b that are perpendicular to each other, the first portion 200a has a first outer edge L2 and a first inner edge L1 that are parallel to each other, and connects the first outer edge L2 with a first end edge E0 of the first inner edge L1, the second portion 200b has a second outer edge and a second inner edge that are parallel to each other, and connects the second outer edge with a second end edge (not labeled) of the second inner edge, the first inner edge L1 with the second inner edge is perpendicularly connected, the first outer edge L2 is perpendicularly connected with the second outer edge, the first outer edge L2 has a first length dimension, the first inner edge L1 has a second length dimension, and the first length dimension is greater than the second length dimension.
It should be noted that there is no obvious distinction between the first portion 200a and the second portion 200b, and the subsequent optical proximity correction method can be adopted to process the patterns in either the horizontal direction or the vertical direction, and the processing effect is the same. For convenience of illustration, in the present embodiment, the first portion 200a is indicated as a figure in a horizontal direction, and in other embodiments, the first portion may also be a figure in a vertical direction.
After the initial pattern 200 is provided, an optimal segment length range is obtained according to the exposure parameters.
In the present embodiment, the exposure parameter refers to an exposure parameter used in exposure processing performed after the optical proximity correction is performed on the initial pattern 200. Specifically, the exposure parameters include: numerical aperture NA, exposure wavelength λ, and light source parameter σ.
The numerical aperture NA of an optical system is a dimensionless number that measures the angular range of light that the system can collect. The exact definition of the numerical aperture NA varies slightly in different fields of optics. In the optical field, the numerical aperture NA describes the size of the light-receiving cone angle of the lens, and the latter determines the light-receiving capacity and the spatial resolution of the lens; in the field of optical fibers, the numerical aperture NA describes the cone angle size of light entering and exiting the fiber. The light source parameter σ includes: luminous flux, illuminance, light intensity, and brightness, etc.
In this embodiment, the method of obtaining the optimal segment length range according to the exposure parameters includes: acquiring a Nyquist value according to the numerical aperture NA, the exposure wavelength lambda and the light source parameter sigma, wherein:
the optimal segment length range is: [1.5Nyquist, 3Nyquist ].
It should be noted that the f (×) function in the above formula is determined according to different types of processing machines, and is specifically provided by corresponding manufacturers.
In this embodiment, a specific example is shown, where a Nyquist value Nyquist obtained according to the numerical aperture NA, the exposure wavelength λ, and the light source parameter σ is 27 nanometers, and the corresponding optimal segment length range is: [40.5,80].
After the optimal segment length range is obtained, a plurality of sampling lengths are obtained according to sampling step sizes in the optimal segment length range, and the minimum difference value among different sampling lengths is the sampling step size.
The range of the sampling step length is as follows: 4 to 6 nanometers. In this embodiment, the sampling step size is 5 nm. The optimal segment length range can be divided into 9 segments of sampling lengths with different lengths by a sampling step length of 5 nanometers, specifically: 40 nm, 45 nm, 50 nm, … … 70 nm, 75 nm and 80 nm, and the total is 9 values.
It should be noted that the optimal segment length range is 1.5 to 3 times of [1.5Nyquist, 3Nyquist ] which is an empirical value summarized after many experiments, and although 40 nm does not belong to the interval range of [40.5,80], since the difference between 40 nm and 40.5 nm is smaller than the sampling step, in order to obtain more sampling lengths, the sampling length of 40 nm may be adopted, and the influence on subsequent results is small. And after 80 nanometers, the sampling step length is increased by 1, the sampling step length is 85 nanometers, and the difference value between 85 nanometers and 81 nanometers is larger than the sampling step length, so that the value of 85 nanometers is abandoned.
Referring to fig. 5, the first outer edge L2 and the first inner edge L1 are segmented to obtain a plurality of first edge segments SLC, a plurality of second edge segments SLE, and a plurality of middle segments SLR, the first outer edge L2 includes the first edge segments SLC, the second edge segments SLE, and a plurality of middle segments SLR located between the first edge segments SLC and the second edge segments SLE, the first inner edge L1 includes the first edge segments SLC, the second edge segments SLE, and a plurality of middle segments SLR located between the first edge segments SLC and the second edge segments SLE, and the number of the middle segments SLR of the first outer edge L2 is greater than the number of the middle segments SLR of the first inner edge L1.
It should be noted that, the first outer edge L2 and the first inner edge L1 are divided into three types of line segments, and when the respective line segments are assigned in the following, the assignments of the first outer edge L2 and the first edge segment SLC of the first inner edge L1 are kept consistent, the assignments of the first outer edge L2 and the second edge segment SLE of the first inner edge L1 are kept consistent, and the assignments of the middle segment SLR of the first outer edge L2 and the first inner edge L1 are kept consistent.
In this embodiment, the number of the intermediate segments SLR of the first outer edge L2 is 2; the number of the middle segments SLR of the first inner edge L1 is 1.
Referring to fig. 5, the lengths of the first edge segment SLC, the second edge segment SLE and the middle segment SLR are assigned by using the sampling lengths, and a plurality of initial segmentation graphs 300 corresponding to the initial graph 200 are obtained.
In this embodiment, since each type of line segment, i.e., the first edge segment SLC, the middle segment SLR, and the second edge segment SLE, has the value of 9, 9 × 9 types of the initial segmentation graphs 300 can be obtained after the full permutation and combination assignment.
It should be noted that, taking 158 nm as an example of the first inner edge L1, although there are 9 × 9 segment combinations altogether, these combinations do not have exactly three types of line segment lengths added up to 158 nm, and if the first edge segment SLC is assigned 40 nm and the second edge segment SLE is assigned 40 nm, then the length of the middle segment SLR is left to be 78 nm, and 78 nm does not belong to any assignment. In this case, the intermediate stage SLR is treated to have a length of 78 nm. The rest of the cases also refer to this processing mode to perform the segmentation operation.
Referring to fig. 6, a plurality of first optical proximity corrections and exposures are performed on each of the initial segmentation patterns 300 to obtain a corresponding first exposure pattern 400.
In this embodiment, after acquiring a plurality of types of the initial segmentation patterns 300, a conventional optical proximity correction process is performed by using model-based optical proximity correction control software, that is, line segments with determined sampling lengths are correspondingly translated to obtain a first correction pattern (not shown), and after obtaining the first correction pattern, an exposure process is performed to obtain the first exposure pattern 400.
Referring to fig. 7, according to each of the initial division patterns 300 and the corresponding first exposure patterns 400, an end-placement edge error EPE0 corresponding to the first end edge E0, a first edge-placement error EPE1 of the first edge segment SLC, a second edge-placement error EPE2 of the second edge segment SLE, and a middle-placement edge error EPE3 of the middle segment SLR are obtained.
It should be noted that, acquiring the end-placement edge error EPE0 corresponding to the first end edge E0, the first edge-placement error EPE1 of the first edge segment SLC, the second edge-placement edge error EPE2 of the second edge segment SLE, and the middle-placement edge error EPE3 of the middle segment SLR according to each of the initial division patterns and the corresponding first exposure pattern means: the first exposure pattern 400 is also segmented, the number of segments corresponds to the number and length of the corresponding segments in the initial segmentation pattern 300, and the distance between the two corresponding segments is obtained, i.e., the end placement edge error EPE0, the first edge placement error EPE1, the second placement edge error EPE2, and the intermediate placement edge errors EPE3 are obtained.
Referring to fig. 8, a segment pattern 500 is obtained from a plurality of the initial segment patterns 400 according to each of the corresponding end placement edge errors EPE0, first edge placement error EPE1, second edge placement error EPE2, and intermediate placement edge errors EPE 3.
In this embodiment, an optimal segment length range is obtained through exposure parameters, and a plurality of sampling lengths are obtained according to sampling step lengths within the optimal segment length range, where a minimum difference value between different sampling lengths is the sampling step. Obtaining a plurality of first edge segments SLC, a plurality of second edge segments SLE and a plurality of middle segments SLR by performing segmentation processing on the first outer edge L2 and the first inner edge L1, where the first outer edge L2 includes the first edge segment SLC, the second edge segment SLE, and the plurality of middle segments SLR located between the first edge segment SLC and the second edge segment SLE, and the first inner edge L1 includes the first edge segment SLC, the second edge segment SLE, and the plurality of middle segments SLR located between the first edge segment SLC and the second edge segment SLE; and carrying out full permutation, combination and assignment on the lengths of the first edge segment SLC, the second edge segment SLE and the middle segment SLR by adopting a plurality of sampling lengths to obtain a plurality of initial segmentation graphs 300 corresponding to the initial graph 200; performing a plurality of first optical proximity corrections and exposure processes on each of the initial segmentation patterns 300 to obtain a corresponding first exposure pattern 400; acquiring an end placement edge error EPE0 corresponding to the first end edge E0, a first edge placement error EPE1 of the first edge segment SLC, a second placement edge error EPE2 of the second edge segment SLE, and a middle placement edge error EPE3 of the middle segment SLR according to each of the initial division patterns 300 and the corresponding first exposure patterns 400; a segmentation map 500 is obtained from a number of the initial segmentation maps 300 according to each of the corresponding end placement edge errors EPE0, first edge placement error EPE1, second placement edge error EPE2, and number of middle placement edge errors EPE 3. On the premise of mask manufacturing capability, exposure parameters and the characteristics of the graph are comprehensively considered, a plurality of segmentation schemes are carried out on the initial graph, the optimal segmentation collocation of the initial graph 200 is obtained through final screening, the conflict between outward extension and MRC when the graph line end is subjected to optical proximity correction is effectively avoided, the edge placement error at the graph line end is effectively reduced, and the problem that the graph line end is seriously shrunk after correction exposure is further solved.
In the present embodiment, the method of obtaining a segmentation graph 500 from a plurality of the initial segmentation graphs 300 according to each of the corresponding end placement edge errors EPE0, first edge placement error EPE1, second placement edge error EPE2, and plurality of intermediate placement edge errors EPE3 includes: obtaining proportioning values of each corresponding end placement edge error EPE0, first edge placement error EPE1, second placement edge error EPE2 and a plurality of middle placement edge errors EPE 3; the initial segmentation graph 300 corresponding to the minimum matching value is used as the segmentation graph 500.
In this embodiment, the method of obtaining the ratio of each corresponding end placement edge error EPE0, first edge placement error EPE1, second placement edge error EPE2, and intermediate placement edge errors EPE3 includes: obtaining a ratio value for each corresponding end placement edge error EPE0, first edge placement error EPE1, second placement edge error EPE2, and number of intermediate placement edge errors EPE3 according to a root mean square RMS formula, wherein:
wherein, EPEiFor the end placement edge error EPE0, first edge placement error EPE1, second placement edge error EPE2, or several intermediate placement edge errors EPE3, WiWeights corresponding to the end placement edge error EPE0, first edge placement error EPE1, second placement edge error EPE2, or intermediate placement edge errors EPE 3.
It should be noted that the weight W corresponding to the end placement edge error EPE0, the first edge placement error EPE1, the second placement edge error EPE2, or the plurality of intermediate placement edge errors EPE3iAnd also based on empirical distribution during actual operation.
In this embodiment, after the initial segmentation graph 300 corresponding to the minimum matching value is taken as the segmentation graph 500, the method further includes: and updating the optical proximity correction method to an optical proximity correction model library.
In this embodiment, the optical proximity correction method is updated to the optical proximity correction model library, so that the optical proximity correction method of the present embodiment can be directly adopted when the same type of graphics processing is performed subsequently.
Referring to fig. 9, after the initial segmentation graph 300 corresponding to the minimum matching value is used as the segmentation graph 500, the method further includes: the division pattern 500 is subjected to a plurality of second optical proximity corrections and exposure processes to obtain a second exposure pattern 600.
In this embodiment, after the optimal initial segmentation pattern 300 is determined and is used as the final segmentation pattern 500, a conventional optical proximity correction process is performed by using model-based optical proximity correction control software, that is, line segments with determined sampling lengths are correspondingly translated to obtain a second correction pattern (not shown), and after the second correction pattern is obtained, an exposure process is performed to obtain the second exposure pattern 600.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (9)
1. An optical proximity correction method, comprising:
providing an initial pattern, the initial pattern having a first portion and a second portion that are perpendicular to each other, the first portion having a first outer edge and a first inner edge that are parallel to each other, and connecting the first outer edge with a first end edge of the first inner edge, the second portion having a second outer edge and a second inner edge that are parallel to each other, and connecting the second outer edge with a second end edge of the second inner edge, the first inner edge being perpendicularly connected to the second inner edge, the first outer edge being perpendicularly connected to the second outer edge, the first outer edge having a first length dimension, the first inner edge having a second length dimension, and the first length dimension being greater than the second length dimension;
obtaining an optimal segment length range according to the exposure parameters;
acquiring a plurality of sampling lengths within the optimal segmentation length range according to sampling step length, wherein the minimum difference value among different sampling lengths is the sampling step length;
the first outer edge and the first inner edge are subjected to segmentation processing to obtain a plurality of first edge sections, a plurality of second edge sections and a plurality of middle sections, the first outer edge comprises the first edge sections, the second edge sections and a plurality of middle sections positioned between the first edge sections and the second edge sections, the first inner edge comprises the first edge sections, the second edge sections and a plurality of middle sections positioned between the first edge sections and the second edge sections, and the number of the middle sections of the first outer edge is greater than that of the middle sections of the first inner edge;
adopting a plurality of sampling lengths to carry out full-permutation combination assignment on the lengths of the first edge section, the second edge section and the middle section, and obtaining a plurality of initial segmentation graphs corresponding to the initial graphs;
carrying out a plurality of times of first optical proximity correction and exposure processing on each initial segmentation graph to obtain a corresponding first exposure graph;
according to each initial segmentation graph and the corresponding first exposure graph, acquiring an end placement edge error corresponding to the first end edge, a first edge placement error of the first edge section, a second placement edge error of the second edge section and a middle placement edge error of the middle section;
and acquiring a segmentation graph from the plurality of initial segmentation graphs according to each corresponding end placement edge error, first edge placement error, second placement edge error and a plurality of middle placement edge errors.
2. The optical proximity correction method of claim 1, wherein the exposure parameters include: numerical aperture NA, exposure wavelength λ, and light source parameter σ.
3. The optical proximity correction method according to claim 2, wherein the method of obtaining the optimum segment length range from the exposure parameter comprises: acquiring a Nyquist value according to the numerical aperture NA, the exposure wavelength lambda and the light source parameter sigma, wherein:
the optimal segment length range is: [1.5Nyquist, 3Nyquist ].
4. The optical proximity correction method of claim 1, wherein the range of sampling steps is: 4 to 6 nanometers.
5. The method of claim 1, wherein obtaining a segmentation map from a plurality of the initial segmentation maps based on each of the corresponding end placement edge errors, first edge placement errors, second placement edge errors, and plurality of intermediate placement edge errors comprises: obtaining the ratio of each corresponding end placement edge error, first edge placement error, second edge placement error and a plurality of middle placement edge errors; and taking the initial segmentation graph corresponding to the minimum matching value as the segmentation graph.
6. The optical proximity correction method of claim 5, wherein obtaining a recipe value for each of the corresponding end placement edge error, first edge placement error, second placement edge error, and intermediate placement edge errors comprises: obtaining the proportion value of each corresponding end placement edge error, first edge placement error, second placement edge error and a plurality of middle placement edge errors according to a Root Mean Square (RMS) formula, wherein:
wherein, EPEiFor said end placement edge error, first edge placement error, second placement edge error or several intermediate placement edge errors, WiPlacing an edge error, a first edge placement error, a second edge placement error for the endAnd placing weights corresponding to the edge errors or the edge errors in the middle.
7. The optical proximity correction method of claim 1, wherein after the initial segmentation pattern corresponding to the minimum matching value is used as the segmentation pattern, the method further comprises: and updating the optical proximity correction method to an optical proximity correction model library.
8. The optical proximity correction method of claim 1, wherein after the initial segmentation pattern corresponding to the minimum matching value is used as the segmentation pattern, the method further comprises: and carrying out a plurality of times of second optical proximity correction and exposure processing on the segmentation graph to obtain a second exposure graph.
9. The optical proximity correction method of claim 1, wherein the number of the middle segments of the first outer edge is 2; the number of the middle sections of the first inner edge is 1.
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