Systems, software applications, and methods for lithographic stitching - Patents.com

Abstract

An embodiment of the present disclosure relates to a method for positioning a mask in a propagation direction of a light source, the mask corresponding to a pattern to be written in a photoresist layer of a substrate. The mask is positioned by stitching a first mask and a second mask. The first mask includes a set of first features having first feature extensions extending therefrom at first feature junction boundaries. The second mask includes a set of second features having second feature extensions extending therefrom at second feature junction boundaries. Each first feature extension is stitched with a corresponding second feature extension to form a respective stitched portion of a first stitched portion of a first pair of masks. The stitched portions of the first pair of masks define a portion of the pattern to be written in the photoresist layer.

Description

[Technical field]

[0001]

[0001] Embodiments of the present disclosure relate generally to photolithography systems and, more particularly, to systems, software applications, and methods for stitching joints between masks. [Background technology]

[0002] Photolithography is widely used in the manufacture of semiconductor devices, such as back-end processing of semiconductor devices, and in the manufacture of display devices, such as liquid crystal displays (LCDs). In the manufacture of display devices, such as optical chips used in augmented reality or virtual reality (AR / VR) devices, large area substrates are often used. A photolithography system has a projection unit that projects a writing beam in the direction of one or more masks. The one or more masks have a pattern corresponding to a pattern to be written in a photoresist layer on the surface of the substrate. However, a single mask pattern transferred by a photolithography system does not necessarily cover the entire area of ​​the substrate. Furthermore, although multiple mask patterns can be transferred adjacent to each other to cover a large area, stitching areas at the joints between the masks may form gaps in the pattern written in the photoresist layer. The gaps in the pattern written in the photoresist form pattern defects, thereby reducing the quality of the display device. Therefore, there is a need in the art for an improved method for lithographic stitching of masks. Summary of the Invention

[0003] In one embodiment, a method is provided. The method includes arranging two or more masks in a propagation direction of a light source, the masks corresponding to a pattern to be written in a photoresist layer of a substrate disposed below the masks. Arranging the masks includes stitching a pair of masks. A first mask in the pair includes a set of first features, the first features having first feature extensions extending therefrom at a first feature junction boundary, and a second mask includes a set of second features, the second features having second feature extensions extending therefrom at a second feature junction boundary. Each first feature extension stitches with a corresponding second feature extension to form a respective stitched portion of the first stitched portion of the first pair of masks, the stitched portions of the first pair of masks defining a portion of the pattern to be written in the photoresist layer.

[0004] In another embodiment, a non-transitory computer readable medium is provided. The non-transitory computer readable medium includes a set of instructions that, when executed by a processor, causes a computer system to create a design file having a pattern to be written into a photoresist layer. The computer system then divides the design file among two or more mask patterns and generates a plurality of features for each of the mask patterns. The features of each mask pattern include a first feature extension to be stitched with a second feature extension of an adjacent mask pattern, and the first feature extension stitched with the second feature extension defines a portion of the pattern to be written into the photoresist layer at the junction of the two or more masks formed from the two or more mask patterns.

[0005] In another embodiment, a non-transitory computer readable medium is provided. The non-transitory computer readable medium includes a set of instructions that, when executed by a processor, causes a computer system to split a design file between two or more mask patterns. The computer system then generates a model of a stitched portion of the two or more mask patterns using one or more of θ1=f(L1, λ1, Δ), Δ=f(L1, λ1, θ1), θ2=f(L2, λ2, Δ), Δ=f(L2, λ2, θ2). The stitched portion includes a first feature having a first feature extension extending therefrom at a first feature junction boundary and a corresponding second feature having a second feature extension extending therefrom at a second feature junction boundary. The first feature end location (θ1) is a distance from each second feature junction boundary to an opposite end of each corresponding first feature extension in each stitched portion. The stitching shift (Δ) is half the distance from each first feature junction boundary of each stitched portion to each corresponding second feature junction boundary. The first feature width (L1) is the first feature width at each first feature junction boundary of each stitched portion. The first feature extension length (λ1) is the length of each first feature extension. The second feature end location (θ2) is the distance from each first feature junction boundary of each stitched portion to the opposite end of each corresponding second feature extension. The second feature width (L2) is the second feature width at each second feature junction boundary of each stitched portion. The second feature extension length (λ2) is the length of each second feature extension.

[0006]

[0006] In order that the above-mentioned features of the present disclosure may be understood in detail, a more particular description of the present disclosure briefly summarized above will be made by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only typical embodiments of the present disclosure and therefore should not be considered as limiting its scope, and that the present disclosure may admit of other equally effective embodiments. [Brief description of the drawings]

[0007] [Figure 1A] FIG. 1 is a schematic diagram of a lithography system according to an embodiment. [Figure 1B] 1 is a schematic plan view of a substrate exposed to a lithographic process; [Diagram 2] 1 is a schematic diagram of a lithographic environment in accordance with one embodiment. [Diagram 3] 1 is a flow diagram of a lithography process according to one embodiment. [Figure 4A] FIG. 2 is an illustration of a mask pattern file according to one embodiment. [Figure 4B] FIG. 2 is an illustration of a mask pattern file according to one embodiment. [Figure 4C] FIG. 13 is an illustration of a stitched portion according to one embodiment. [Figure 4D] FIG. 2 is an illustration of a mask pattern file according to one embodiment. [Figure 4E] FIG. 2 is an illustration of a mask pattern file according to one embodiment. [Fig. 4F-4I] FIG. 13 is an illustration of a feature extension according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008]

[0015] For ease of understanding, the same reference numbers have been used, where possible, to designate identical elements common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific remark.

[0009]

[0016] The embodiments of the present disclosure relate to systems, software applications, and methods for lithographic stitching. Some embodiments of the method include arranging two or more masks in a propagation direction of a light source. The masks correspond to a pattern to be written in a photoresist layer of a substrate disposed below the masks. Arranging the masks includes stitching a pair of masks. A first mask in the pair includes a set of first features, the first features having first feature extensions extending therefrom at a first feature junction boundary, and a second mask includes a set of second features, the second features having second feature extensions extending therefrom at a second feature junction boundary. Each first feature extension stitches with a corresponding second feature extension to form a respective stitched portion of the first stitched portion of the first pair of masks, the stitched portions of the first pair of masks defining a portion of the pattern to be written in the photoresist layer.

[0010]

[0017] FIG. 1A is a schematic diagram of a lithography system 100. FIG. 1B is a schematic plan view of a substrate 106 exposed to a lithography process. It will be understood that the lithography system 100 is an exemplary system and that other systems, including systems from other manufacturers, may be used or modified to achieve aspects of the present disclosure. The system includes a projection unit 102 including one or more light sources, such as light emitting diodes (LEDs) or lasers, capable of projecting a writing beam in the direction of two or more masks 104a, 104b, 104c, ... 104(n-1), 104n (collectively referred to as "two or more masks 104"). The masks are disposed above the substrate 106. The two or more masks 104 may have mask patterns 405a, 405b, 405c, ... 405(n-1), 405n (collectively referred to as "mask patterns 405" shown in FIG. 4A and FIG. 4B).

[0011]

[0018] The substrate 106 comprises any suitable material, for example, glass used as part of a flat panel display. In some embodiments that can be combined with other embodiments described herein, the substrate 106 is made of other materials that can be used as part of a flat panel display. In other embodiments that can be combined with other embodiments described herein, the substrate can have a surface width of about 5 mm to about 70 mm, for example, about 5 mm to about 100 mm, for example, about 5 mm to about 20 mm, or about 50 mm to 60 mm. In some embodiments that can be combined with other embodiments described herein, the substrate can have a surface length of about 5 mm to about 100 mm, for example, about 5 mm to about 60 mm, for example, about 5 mm to about 20 mm, or about 50 mm to 60 mm. For example, the substrate can have dimensions of about 30 mm to about 60 mm by about 25 mm to about 60 mm. The substrate 106 has a film layer formed thereon to be patterned (e.g., by pattern etching) and a photoresist layer 110 formed on the film layer to be patterned that is sensitive to electromagnetic radiation, e.g., ultraviolet (UV), extreme ultraviolet (EUV) or deep UV "light." A positive photoresist includes portions of the photoresist layer 110 that, upon exposure to radiation, become soluble in a photoresist developer applied to the photoresist layer 110 after a pattern has been written into the photoresist layer 110 using electromagnetic radiation, respectively. A negative photoresist includes portions of the photoresist layer 110 that, upon exposure to radiation, become insoluble in a photoresist developer applied to the photoresist layer 110 after a pattern has been written into the photoresist layer 110 using electromagnetic radiation, respectively. A negative development includes a positive photoresist layer 110 exposed through a bright field mask, such that the exposed areas become insoluble in organic solvents (e.g., n-butanol), respectively, and will remain on the wafer after development. The chemical composition of the photoresist layer 110 determines whether the photoresist layer 110 is a positive photoresist or a negative photoresist.

[0012]

[0019] During operation, the projection unit 102 projects a writing beam in the direction of one or more of the masks 104. The mask patterns 405 of the two or more masks 104 arranged according to the embodiment of the method 300 described herein correspond to the device patterns 112 written in the photoresist layer 110 when the writing beam is projected in the direction of one or more of the masks 104. The device portions 114 of the device patterns 112 written in the photoresist layer 110 correspond to stitched portions 403a, 403b, ... 403(n-1) of the mask patterns 405 (collectively referred to as "stitched portions 403" shown in Figures 4B and 4C). The feature extensions 407 of the mask patterns 405 of the mating masks of the two or more masks 104 (shown in Figures 4A and 4B) are modeled and arranged to be stitched. To achieve pattern stitching, the mask patterns 405 of the different masks are acquired in separate exposures and are superimposed on each other. In an exemplary lithography exposure process, a first mask 104a is loaded and then exposed to form a first mask pattern 405a written into the photoresist layer 110, then a second mask 104b is loaded and then exposed to form a second mask pattern 405b, and the first and second feature extension patterns are superimposed to result in a stitched mask pattern 405. The feature extensions 407 of the mating masks of the two or more masks 104 are modeled and positioned (i.e., superimposed) such that the device pattern 112 is substantially seamless in the device portion 114. In some embodiments, which can be combined with other embodiments described herein, the feature extensions 407 of the mating masks of the two or more masks 104 are modeled and positioned such that the device pattern 112 is seamless in the device portion 114 written into the photoresist layer 110. In some embodiments, which can be combined with other embodiments described herein, the device pattern 112 may correspond to a device patterned on the substrate 106 or a film layer disposed on the substrate 106.In other embodiments, which can be combined with other embodiments described herein, the device pattern 112 may correspond to one or more devices patterned on the substrate 106 or a film layer disposed on the substrate 106.

[0013]

[0020] In some embodiments, which can be combined with other embodiments described herein, the lithography system 100 is sized to expose the entire photoresist layer on the substrate 106. In other embodiments, which can be combined with other embodiments described herein, the substrate 106 can be supported by a stage 116 operable to position the substrate 106 in a predetermined path under one or more of the masks 104. The movement of the substrate can be controlled by a controller 108. The controller 108 is generally designed to facilitate control and automation of the lithography process based on a mask pattern file. The mask pattern file (e.g., the mask pattern file 400 shown in Figures 4A and 4B) includes mask pattern data having instructions for positioning two or more masks 104 according to an embodiment of the method 300 described herein. The controller 108 can be coupled to or in communication with at least the projection unit 102, the stage 116, and the encoder 118. The projection unit 102 and the encoder 118 can provide information regarding substrate processing and substrate alignment to the controller 108. For example, the projection unit 102 may provide information to the controller 108 to alert the controller 108 that substrate processing is complete.

[0014]

[0021] 2 is a schematic diagram of a lithography environment 200. As shown in FIG. 2, the lithography environment 200 includes, but is not limited to, a virtual design apparatus 202, a mask modeling apparatus 204, a mask manufacturing apparatus 206, a lithography system 100, a controller 210, a number of communication links 201, and a transport system 203. Each of the lithography environment apparatuses is operable to be connected to the controller 210 by the communication links 201. Alternatively or additionally, each of the lithography environment apparatuses can communicate indirectly by first communicating with the controller 210, which in turn communicates with the lithography environment apparatus in question. Each of the lithography environment apparatuses of the lithography environment 200 can be located in the same area or production facility, or each of the lithography environment apparatuses can be located in different areas.

[0015]

[0022] The virtual design device 202 is operable to at least one of create, optimize, verify, and update a design file. The design file corresponds to the device pattern 112 to be written in the photoresist layer 110. The mask modeling device 204 is operable to split the design file and generate a mask pattern file 400 according to the steps of the method 300 described herein. The mask pattern file 400 includes mask pattern data of the two or more masks 104 according to the steps of the method 300 described herein. The mask manufacturing device 206 is operable to receive the mask pattern data of the two or more masks 104 transmitted from the mask modeling device 204. According to the steps of the method 300 described herein, the mask manufacturing device 206 is operable to manufacture mask patterns 405 of the two or more masks 104 corresponding to the device pattern 112 to be written in the photoresist layer 110 when the two or more masks 104 are positioned according to the embodiments described herein. The lithography system 100 is operable to receive two or more masks 104 according to the steps of the method 300 described herein.

[0016]

[0023] Further, each of the plurality of lithography environment devices is shown in the steps of the method 300 described herein. Each of the virtual design device 202, the mask modeling device 204, the mask making device 206, the lithography system 100, and the controller 210 includes an on-board processor and memory, the memory configured to store instructions corresponding to any portion of the method 300 described below. The communication link 201 may include at least one of a wired connection, a wireless connection, a satellite connection, and the like. According to an embodiment further described herein, the communication link 201 includes sending and receiving a universal metrology file (UMF) or any other file used to store data. The communication link 201 may include temporarily or permanently storing the file or data in a cloud before transferring or copying the file or data to a lithography system tool. The mask making device 206 and the mask modeling device 204 are connected by a transport system 203. The transport system 203 is operable to transport a substrate between the mask making device 206 and the lithography system 100. In an embodiment, which may be combined with other embodiments described herein, the transport system 203 may include a robot or other device operable to transport one or more masks 104 and connectable to the controller 210. In an embodiment, which may be combined with other embodiments described herein, the transport system 203 may be physically manipulated by a user.

[0017]

[0024] The controller 210 includes a central processing unit (CPU) 212, support circuits 214, and memory 216. The CPU 212 can be one of any form of computer processor that can be used in an industrial environment to control lithography environment equipment. The memory 216 is coupled to the CPU 212. The memory 216 can be one or more readily available memories, such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote. The support circuits 214 are coupled to the CPU 212 to support the processor in a conventional manner. These circuits include cache, power supplies, clock circuits, input / output circuits, subsystems, and the like. The controller 210 can include the CPU 212 coupled to input / output (I / O) devices found in the support circuits 214 and in the memory 216.

[0018]

[0025] The memory 216 may include one or more software applications, such as a control software program. The memory 216 may also include stored media data used by the CPU 212 to execute the method 300 described herein. The CPU 212 may be a hardware unit or combination of hardware units capable of executing software applications and processing data. The CPU 212 is generally configured to execute one or more software applications and process stored media data, each of which may be included within the memory 216. The controller 210 controls the transfer of data and files to and from various lithography environment devices. The memory 216 is configured to store instructions corresponding to any step of the method 300 according to the embodiments described herein.

[0019]

[0026] 3 is a flow diagram of a method 300 of a lithography process. In optional step 301, a design file is created by a virtual design device 202. The design file corresponds to a device pattern 112 to be written in a photoresist layer 110. In some embodiments, which can be combined with other embodiments described herein, the design file is created prior to the steps of the method 300 described herein. In step 302, a mask modeling device 204 splits the design file and generates a mask pattern file 400 having mask pattern data for two or more masks 104 (as shown and described in FIGS. 4A, 4B, 4D, and 4E).

[0020]

[0027] In step 303, the mask making device 206 manufactures mask patterns 405 of two or more masks 104 corresponding to the device pattern 112 to be written in the photoresist layer 110 when the two or more masks 104 are arranged according to the embodiments described herein. In step 304, the two or more masks 104 are received by the lithography system 100 and arranged separately under the projection unit 102 according to the mask pattern data in which the feature extensions 407 of the mask patterns 405 of the adjacent masks 104 are stitched. The feature extensions 407 of the mask patterns 405 of the adjacent masks of the two or more masks 104 (shown in Figures 4A and 4B) are modeled and arranged to be stitched. To achieve the pattern stitching, the mask patterns 405 of the different masks are acquired in separate exposures and are superimposed with each other. In an exemplary lithography exposure process, a first mask 104a is loaded and then exposed to form a first mask pattern 405a written into the photoresist layer 110, then a second mask 104b is loaded and then exposed to form a second mask pattern 405b, and the first and second feature extension patterns are overlaid to result in a stitched mask pattern 405.

[0021]

[0028] 4A and 4B are diagrams illustrating a mask pattern file 400. As shown in FIG. 4A, the feature extensions 407 of the mask patterns 405 of the joined masks of the two or more masks 104 are not stitched. As shown in FIG. 4B, the feature extensions 407a, 407b, 407c, 407d, 407e...407(n-1), 407n, 407(n+1) (collectively referred to as "feature extensions 407" shown in FIG. 4A and FIG. 4B) of the mask patterns 405 of the joined masks of the two or more masks 104 are stitched according to the mask pattern data of the mask pattern file 400 as described in step 304. The mask pattern file 400 includes two or more masks 104 having features 402a, 402b, 402c, ... 402(n-1), 402n (collectively referred to as "features 402" shown in Figures 4A and 4B) of a mask pattern 405. The stitched portion 403 includes feature extensions 407 of the features 402 to be stitched together. For example, the stitched portion 403a is a stitch between features 402a and 402b.

[0022]

[0029] For example, as shown in Figures 4A and 4B, a first pair of masks including a first mask 104a and a second mask 104b are shown. The first mask 104a has a first set of features having first feature extensions 407a extending from a first feature junction boundary 406a to an opposite end 408a of the first feature extension. The second mask 104b has a second set of features having second feature extensions 407b extending from a second feature junction boundary 406b to an opposite end 408b of the second feature extension. The first feature extensions 407a are stitched with corresponding second feature extensions 407b in a first stitched portion 403a of the first pair of mask patterns (e.g., 405a and 405b). As shown in Figures 4A and 4B, a second pair of masks including a second mask 104b and a third mask 104c is shown. The second mask is stitched with the third mask to form a second stitched portion 403b of the second pair of masks. In some embodiments that can be combined with other embodiments described herein, a single mask can be stitched with one or more additional masks according to some embodiments of the present disclosure. As shown in Figures 4A and 4B, the nth mask 104n can be stitched with the adjacent (n-1)th mask 104(n-1) at the stitched portion 403(n-1). The feature extension 407 of the joining portion is modeled and stitched as described and shown in Figure 4C.

[0023]

[0030] FIG. 4C is an illustration of a stitched portion 403. As shown in FIG. 4C, several parameters can be used to model the mask pattern design of each pair of overlapping mask patterns (e.g., 405a and 405b, 405b and 405c, ... 405(n-1) and 405n) of each stitched portion 403. In one example, a first pair of overlapping mask patterns (e.g., 405a and 405b) having a first mask pattern 405a and a second mask pattern 405b that overlap in the stitched portion 403 is provided. Each of the parameters described herein is described with reference to a first feature 402a and a second feature 402b of the first pair of stitched masks of the stitched portion 403.

[0024]

[0031] The first feature width L1 of the stitched portion 403 represents a width at a first feature junction boundary 406a between the first feature 402a and the first feature extension 407a of the mask pattern 405. The second feature width L2 represents a width at a second feature junction boundary 406b between the second feature 402b and the second feature extension 407b of the mask pattern 405. The feature widths L1 and L2 as used herein may be collectively referred to as "L". The stitched portion 403 further provides a first feature end location θ1, which is a distance from the second feature junction boundary 406b in the stitched portion 403 to an opposite end 408a of the corresponding first feature extension 407a. The second feature end location θ2 is a distance from the first feature junction boundary 406a in the stitched portion 403 to an opposite end 408b of the corresponding second feature extension 407b. The feature end locations θ1 and θ2 used herein can be collectively referred to as “θ”. The stitching shift Δ is half the distance from the first feature junction boundary 406a to the corresponding second feature junction boundary 406b of the stitched portion 403. The first feature extension length (λ1) is the length of each first feature extension 407a. For example, λ1 is the distance from the first feature junction boundary 406a to the opposite end 408a of the stitched portion 403. The second feature extension length λ2 is the length of each second feature extension 407b. For example, λ2 is the distance from the first feature junction boundary 406a to the opposite end 408a of the stitched portion 403.

[0025]

[0032] In one example, when θ1 and θ2 are equal to zero, λ1=λ2=Δ+Δ. In some embodiments that can be combined with other embodiments described herein, θ has a negative value. For example, when the opposite end 408a of the first feature extension 407a is positioned to overlap the second feature extension 407b, but does not overlap the second feature junction boundary 406b, θ1 is negative. In some embodiments that can be combined with other embodiments described herein, θ has a positive value. For example, when the opposite end 408a of the first feature extension 407a overlaps the second feature extension 407b and overlaps the second feature junction boundary 406b, θ1 can be positive. In some embodiments, which can be combined with other embodiments, the mask modeling device 204 generates a model of a stitched portion 403 of two or more mask patterns 405 using θ1=f(L1,λ1,Δ) or Δ=f(L1,λ1,θ), where the stitched portion 403 includes a first feature 402a having a first feature extension 407a extending therefrom at a first feature junction boundary 406a, and a corresponding second feature 402b having a second feature extension 407b extending therefrom at a second feature junction boundary 406b.

[0026]

[0033] Each of the parameters measured for the second feature 402b does not necessarily have the same value as the measured value for the first feature 402a. In some embodiments that can be combined with other embodiments described herein, each first feature junction boundary 406a of the first plurality of feature junction boundaries includes a first feature width (L1) and each second feature junction boundary 406b of the second plurality of feature junction boundaries includes a second feature width (L2). In some embodiments that can be combined with other embodiments described herein, L1 is substantially equal to L2, or L1 is not equal to L2. Similarly, each of the parameters λ and θ may be the same or different between the first feature 402a and the second feature 402b of the stitched portion 403. Furthermore, each mask may have a uniform stitched portion 403, or the stitched portion 403 may be different in different portions of each mask pattern 405.

[0027]

[0034] In some embodiments that can be combined with other embodiments described herein, θ can be determined based on one or more of λ, Δ, L, and combinations thereof. For example, one or more equations such as θ=f(L,λ,Δ), Δ=f(L,λ,θ), θ1=f(L1,λ1,Δ), θ2=f(L2,λ2,Δ), Δ=f(L1,λ1,θ1), Δ=f(L2,λ2,θ2), Δ=f(L1,λ1,θ1)=f(L2,λ2,θ2), or combinations thereof can be modeled or solved for one or more of parameters such as θ, Δ, θ1, θ2, λ1, λ2, or combinations thereof. In some embodiments that can be combined with other embodiments described herein, the feature width (L) at the feature junction boundary (e.g., 406a, 406b) is greater than the opposite end width (e.g., 408a, 408b) of the corresponding feature extension.

[0028]

[0035] 4D and 4E are illustrations of a mask pattern file 400. FIG. 4D shows pitch 422 and pitch 424. Pitch 422 is measured from a first leading edge 421 of feature 410 and a first leading edge 423 of feature 411. Similarly, pitch 424 is measured from a first leading edge 425 of feature 416 and a first leading edge 427 of feature 417. In some embodiments, which can be combined with other embodiments described herein, a model can be generated to determine θ and / or Δ based on the pitch (e.g., 422, 424) between adjacent features of each mask pattern 405. As used herein, “pitch” is the distance between the first leading edges of adjacent features. In some embodiments, which can be combined with other embodiments described herein, a mask pattern (e.g., 405b) can have a uniform pitch (e.g., 422) between features (e.g., 410 and 411). In some embodiments, which can be combined with other embodiments described herein, the mask patterns (e.g., 405b) can have different pitches, as shown by pitches 422 and 424 in FIG. 4D.

[0029]

[0036] In some embodiments, which may be combined with other embodiments described herein, mask patterns may be produced by the methods and systems of the present disclosure. file 400 may also include angled features, as shown in FIG. 4D. As can be seen, the mask pattern file 400 shown in FIG. 4D includes a first mask 104a and a second mask 104b stitched with the first mask 104a at stitched portion 403. Additionally, the features (e.g., 410, 411, 412, 413, 414, 415, 416, and 417) may have different angles β between features (e.g., 410-417) and different pitches (e.g., 422, 424). For example, the features (e.g., 410-417) may be angled β at about 0 degrees, or about 30 degrees, or about 90 degrees, or about 120 degrees, or about 150 degrees.

[0030]

[0037] FIG. 4E further illustrates another exemplary mask pattern file 400 having a first mask 104a and a second mask 104b including a stitched portion 403. The mask pattern file 400 of FIG. 4E illustrates discontinuous features (e.g., 430) rather than continuous features. In some embodiments that can be combined with other embodiments described herein, the features (e.g., 410-417) are line features, as shown in FIG. 4D. As can be seen, many different mask patterns 405 are possible with the stitching method 300 and lithography system 100 of the present disclosure. In some embodiments that can be combined with other embodiments described herein, the stitched portion 403 between adjacent mask patterns (e.g., 405a and 405b) is seamless. In some embodiments that can be combined with other embodiments described herein, Δ is less than λ, e.g., less than half λ. In some embodiments that can be combined with other embodiments described herein, Δ is less than L, e.g., less than 25% of L. With respect to feature width (L), the mask pattern (e.g., 405a) can have a uniform feature width at the feature junction boundaries (e.g., 406a) of the stitched portions (e.g., 403a, 403b, 403c, 403d, 403f), or the mask pattern (e.g., 405a) can have different feature widths (e.g., 432 and 434) at the feature junction boundaries (e.g., 442 and 444) in the stitched portions (e.g., 403d, 403e), as shown in FIG. 4E.

[0031]

[0038] Furthermore, the feature extension shapes can vary in shape depending on one or more of λ, θ, L, Δ, and pitch (e.g., 422, 424). Figures 4F-I show examples of feature extensions 407 having various shapes. In particular, Figure 4F shows a feature extension 407 having a triangular shape, and Figure 4G shows a feature extension 407 having a triangular shape. ConcaveFIG. 4F shows a feature extension 407 having a convex shape, FIG. 4H shows a feature extension 407 having a convex shape, and FIG. 4I shows a feature extension 407 having a right angle shape. For example, referring to FIG. 4F, constants Δ and λ are used as display conditions. If stitching requires more overlap area, the shape of feature extension 407 in FIG. 4G is used. Alternatively, if stitching requires less overlap area, the shape of feature extension 407 in FIG. 4H is used. As seen in FIG. 4I, the shape of feature extension 407 may be asymmetric with respect to an axis (e.g., axis x) perpendicular to the line joining axis (e.g., axis y). For example, the shape of feature extension 407 may be a right angle triangle.

[0032]

[0039] In summary, a method of lithography process is provided that allows for the transfer of a mask pattern to a large substrate with seamless transfer at the stitched portions of the two or more masks by stitching two or more masks. Some embodiments of the method include arranging two or more masks in a propagation direction of a light source. The masks correspond to a pattern to be written in a photoresist layer of a substrate disposed below the masks. Arranging the masks includes stitching a pair of masks. A first mask in the pair includes a set of first features, the first features having first feature extensions extending therefrom at a first feature junction boundary, and a second mask includes a set of second features, the second features having second feature extensions extending therefrom at a second feature junction boundary. Each first feature extension is stitched with a corresponding second feature extension to form a respective stitched portion of the first stitched portion of the first pair of masks, the stitched portions of the first pair of masks defining a portion of a pattern to be written into the photoresist layer.

[0033]

[0040] While the forgoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, which scope is determined by the following claims.

Claims

1. 1. A method comprising placing two or more masks in a direction of propagation of a light source, the mask corresponds to a pattern to be written into a photoresist layer of a substrate disposed beneath the mask; Disposing the mask comprises: determining a first feature edge location (θ1) of a first mask of a first pair of masks including a first mask and a second mask; stitching the first pair of masks together; the first mask includes a set of first features having first feature extensions extending therefrom at first feature junction boundaries; the second mask includes a set of second features having second feature extensions extending therefrom at second feature junction boundaries; each first feature extension stitched with a corresponding second feature extension to form a respective stitched portion of a first stitched portion of the first pair of masks, the stitched portions of the first pair of masks defining a portion of the pattern to be written into the photoresist layer; the first feature end locations (θ1) include distances from each second feature junction boundary to the opposite ends of corresponding first feature extensions in the first stitched portion; and The first feature end location (θ1) is selected from the following (i) to (iii): (i) a pitch between adjacent features of the first mask, the pitch being the distance between first leading edges of each adjacent feature; (ii) a first feature width (L1) that includes a width at each of the first feature junction boundaries of each stitched portion and a stitching shift (Δ) that includes substantially half the distance from each first feature junction boundary of the stitched portion to a corresponding second feature junction boundary; or (iii) a first feature width (L1) comprising a width at each of the first feature junction boundaries of each stitched portion and a first feature extension length (λ1) comprising a length of each first feature extension; is determined based on at least one of determining dimensions of the stitched portion by solving θ1=f(L1, λ1, Δ) or Δ=f(L1, λ1, θ1).

2. each first feature junction boundary comprises a first feature width (L1), each L1 being greater than a width of a corresponding opposite end of said first feature extension; 2. The method of claim 1, wherein each second feature junction boundary comprises a second feature width (L2) defined as a width of each second feature junction boundary, each L2 being greater than a width of a corresponding opposite end of the second feature extension.

3. The method of claim 2 , wherein L1 is substantially equal to L2.

4. The method of claim 2 , wherein L1 is not equal to L2.

5. The method of claim 1 , further comprising: determining a first feature extension shape based on the first feature end location (θ1).

6. The method of claim 5 , wherein the first feature extension shape has one of a triangular shape, a convex shape, and a concave shape.

7. 10. The method of claim 1, further comprising stitching the first mask with a third mask to form a second stitched portion, the second stitched portion defining a second portion of the pattern to be written into the photoresist layer.

8. forming the mask, the forming of the mask comprising: creating a design file having said pattern to be written into a photoresist layer; Dividing the design file among two or more mask patterns; generating a plurality of features for each of the mask patterns; Including, each stitching feature of the mask pattern includes a first feature extension to be stitched with a second feature extension of an adjacent mask pattern; 2. The method of claim 1, wherein the first feature extension stitched with the second feature extension defines a portion of the pattern written into the photoresist layer upon stitching of the mask formed from the mask pattern.

9. A non-transitory computer-readable medium storing instructions, comprising: The instructions, when executed by a processor, cause the computer system to: Creating a design file having a pattern to be written into a photoresist layer; Dividing the design file among a plurality of mask patterns; generating a plurality of features for each of the mask patterns; each overlapping feature of the mask patterns includes a first feature extension extending at a first feature junction boundary to be stitched with a second feature extension extending at a second feature junction boundary of an adjacent mask pattern; generating a plurality of features, each of the first feature extensions to be stitched with each of the second feature extensions comprising a respective stitched portion of the pattern written into the photoresist layer upon stitching of a mask formed from the mask pattern; determining a first feature end location (θ1) comprising a distance from each second feature junction boundary to an opposite end of each first feature extension of each corresponding stitched portion; The first feature end location (θ1) is selected from the following (i) to (iii): (i) a pitch between adjacent features of each mask pattern, the pitch being the distance between the first leading edges of each adjacent feature; (ii) a first feature width (L1) that includes a width at each of the first feature junction boundaries of each stitched portion and a stitching shift (Δ) that includes substantially half the distance from each first feature junction boundary of the stitched portion to a corresponding second feature junction boundary; or (iii) a first feature width (L1) comprising a width at each of the first feature junction boundaries of each stitched portion and a first feature extension length (λ1) comprising a length of each first feature extension; determining a first feature end location (θ1), determined based on at least one of Run the command, The instructions further cause the computer system to determine dimensions of each stitched portion by solving one or more of θ1=f(L1, λ1, Δ), Δ=f(L1, λ1, θ1), θ2=f(L2, λ2, Δ), and Δ=f(L2, λ2, θ2); a second feature end location (θ2) is defined as the distance from each first feature junction boundary in each stitched portion to the opposite end of each corresponding second feature extension; a second feature width (L2) is defined as the second feature width at each of the second feature junction boundaries of each stitched portion; A second feature extension length (λ2) is defined as the length of each second feature extension; Non-transitory computer-readable medium.

10. 10. The non-transitory computer-readable medium of claim 9, wherein the instructions further cause the computer to determine a first feature extension shape based on one or more of θ1, L1, λ1, and Δ.

11. 10. The non-transitory computer-readable medium of claim 9, wherein the first feature end location (θ1) is determined based on the stitching shift (Δ).

12. 10. The non-transitory computer readable medium of claim 9, wherein the first feature end location (θ1) is determined based on the pitch between adjacent features of a mask pattern.

13. A non-transitory computer-readable medium storing instructions, comprising: The instructions, when executed by a processor, cause the computer system to: Dividing the design file between two or more mask patterns; generating a model of the stitched portion of the two or more mask patterns using one or more of θ1=f(L1, λ1, Δ), Δ=f(L1, λ1, θ1), θ2=f(L2, λ2, Δ), and Δ=f(L2, λ2, θ2); Run the command, the stitched portion includes a first feature having a first feature extension extending therefrom at a first feature junction boundary and a second feature having a second feature extension extending therefrom at a second feature junction boundary; a first feature end location (θ1) is defined as the distance from each second feature junction boundary in each stitched portion to an opposite end of each corresponding first feature extension; a stitching shift (Δ) is defined as half the distance from each first feature junction boundary of each stitched portion to each corresponding second feature junction boundary; a first feature width (L1) is defined as the first feature width at each of the first feature junction boundaries of each stitched portion; a first feature extension length (λ1) is defined as the length of each first feature extension; a second feature end location (θ2) is defined as the distance from each first feature junction boundary in each stitched portion to the opposite end of each corresponding second feature extension; a second feature width (L2) is defined as the second feature width at each of the second feature junction boundaries of each stitched portion; A second feature extension length (λ2) is defined as the length of each second feature extension; Non-transitory computer-readable medium.

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