Formation of word line contacts for NAND devices

Abstract

A method for forming word line contacts in a 3D NAND device is disclosed. The method may include providing a film stack of alternating first and second layers, forming a first lithography mask on the film stack, and performing a first series of alternating lithography and etching processes to form an array of contact aperture pairs within the film stack, wherein the apertures passing through the first lithography mask are expanded in a first direction following each etching process, and the depth of the array of contact aperture pairs changes in the first direction. The method may also include forming a second lithography mask on the film stack, and performing a second series of alternating lithography and etching processes, wherein the apertures passing through the second lithography mask are expanded in a second direction following each etching process, and the depth of the array of contact aperture pairs changes in the second direction.

Description

Technical Field

[0001] Related Applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 498,203, filed on April 25, 2023, entitled "Wordline Contact Formation for NAND Device", the entire content of which is incorporated herein by reference.

[0002]

[0002] This embodiment relates to the processing of NAND devices, and more particularly, to a method for forming wordline contacts in 3D NAND devices.

Background Art

[0003]

[0003] In accordance with current substrate (e.g., wafer) manufacturing techniques, etching rate, etching profile, and etching selectivity are optimized to reduce manufacturing costs and increase the circuit element density on the substrate. However, etching features such as memory holes continue to decrease in size and / or increase in aspect ratio (e.g., the ratio of the depth to the width of the feature). For example, in the manufacture of three-dimensional (3D) NAND devices, the substrate can include up to 96 layers and can be extended up to 128 layers. Further, for example, the aspect ratio of memory holes can be between 100 and 200, and the depth of the memory holes can range from about 6 μm to 8 μm, so etching of memory holes becomes one of the most important and difficult processes in manufacturing 3D NAND devices. For example, such high aspect ratio etching requires not only a high etching rate and high etching selectivity to mask the material on the substrate, but also a straight profile without warping or twisting, no under-etching, minimal microloading, minimal aspect ratio dependent etching (ARDE), and uniformity across the substrate (e.g., a 3σ variation in critical dimension (CD) < 1%).

[0004]

[0004] When manufacturing 3D NAND devices in which layers are arranged in a stepped pattern, the formation of word line landing pads is first defined through step formation (e.g., lithography and etching processes) and / or a chop process that etches down multiple layers, after which gap filling of the stepped region may be performed. However, since contact holes of different heights are formed in the same etching process, the selectivity margin during word line contact etching remains a challenge. Furthermore, increasing the temperature of the dry etching process to improve selectivity is limited by hardware constraints.

[0005]

[0005] Direct word line contact formation is one method used to form word line contacts because it eliminates the landing pad formation step. However, especially in the case of contact-first methods, multiple lithography and etching steps are required to form all word line contacts, thus increasing lithography costs. Furthermore, endpoint control is difficult because ARDE plays an important role in dry etching.

[0006]

[0006] This disclosure is presented in connection with the above and other considerations. [Overview of the project]

[0007]

[0007] From the above viewpoint, the method may include providing a film laminate of alternating first and second layers, forming a first lithography mask on the film laminate, and performing a first series of alternating lithography and etching processes to form an array of contact aperture pairs within the film laminate, wherein the apertures passing through the first lithography mask are expanded in a first direction following each etching process, and the depth of the array of contact aperture pairs changes in the first direction. The method may also include forming a second lithography mask on the film laminate, and performing a second series of alternating lithography and etching processes, wherein the apertures passing through the second lithography mask are expanded in a second direction following each etching process, and the depth of the array of contact aperture pairs changes in the second direction. The method may further include removing gap fill from one or more contact openings of an array of contact opening pairs after performing a second series of alternating lithography and etching processes.

[0008]

[0008] In some methods, a method for forming a 3D NAND device may include forming a patterned hard mask and a first lithography mask on a film stack, the patterned hard mask and the first lithography mask comprising a plurality of first and second layers in which the film stacks are arranged alternately; forming openings through the first lithography mask; and etching the film stack through the openings of the first lithography mask to form a first plurality of contact openings within the film stack. The method may further include processing the first lithography mask to expand the openings of the first lithography mask in a first direction; and etching the film stack through the openings of the first lithography mask to form a second plurality of contact openings within the film stack, the etching of the film stack such that the depth of the first plurality of contact openings increases as the second plurality of contact openings are formed. The method may further include forming a second lithography mask on a film stack and etching the film stack through the openings of the second lithography mask to increase the depth of a subset of the first plurality of contact openings and a subset of the second plurality of contact openings. The method may further include processing the second lithography mask to expand the openings of the second lithography mask in a second direction, wherein the second direction is orthogonal to the first direction, and etching the film stack through the openings of the second lithography mask to increase the depth of a second subset of the first plurality of contact openings and a second subset of the second plurality of contact openings, wherein the depth of the first plurality of contact openings and a subset of the second plurality of contact openings changes in the first direction and the second direction. The method may further include removing gap fill from one or more contact openings among the first and second plurality of contact openings after etching the film laminate in order to increase the depth of the second subset of the first plurality of contact openings and the second subset of the second plurality of contact openings.

[0009]

[0009] In some methods, the system may include a processor and a memory for storing instructions that can be executed by the processor. Instructions may include instructions for forming a patterned hard mask and a first lithography mask on a film stack, the patterned hard mask and the first lithography mask including first and second layers in which the film stacks are arranged alternately; forming openings through the first lithography mask; and etching the film stack through the openings of the first lithography mask to form a first plurality of contact openings within the film stack. The memory may further store instructions that can be executed by the processor for processing the first lithography mask to expand the openings of the first lithography mask in a first direction; and etching the film stack through the openings of the first lithography mask to form a second plurality of contact openings within the film stack, the depth of the first plurality of contact openings increasing as the second plurality of contact openings are formed. The memory may further include instructions executable by the processor for performing the following actions: forming a second lithography mask on a film stack; forming openings through the second lithography mask; etching the film stack through the openings of the second lithography mask to increase the depth of a subset of first contact openings and a subset of second contact openings; and processing the second lithography mask to expand the openings of the second lithography mask in a second direction, wherein the second direction is orthogonal to the first direction. The memory may further store instructions executable by the processor for etching a film stack through the openings of a second lithography mask to increase the depth of a second subset of first contact openings and a second subset of second contact openings, wherein the depths of the first and second contact openings vary in a first and second direction.The memory may further store instructions executable by the processor for removing gap fill from one or more contact openings among the first and second plurality of contact openings after etching the film stack in order to increase the depth of a second subset of the first plurality of contact openings and a second subset of the second plurality of contact openings.

[0010]

[0010] The accompanying drawings illustrate exemplary techniques of the present disclosure, including practical applications of the principles of the present disclosure, as follows: [Brief explanation of the drawing]

[0011] [Figure 1A]

[0011] A side cross-sectional view of an exemplary method for forming a plurality of contact openings within a film stack of a device according to an embodiment of the present disclosure is shown. [Figure 1B] This shows a side cross-sectional view of an exemplary method for forming multiple contact openings within a film stack of a device according to embodiments of the present disclosure. [Figure 1C] This shows a side cross-sectional view of an exemplary method for forming multiple contact openings within a film stack of a device according to embodiments of the present disclosure. [Figure 1D] This shows a side cross-sectional view of an exemplary method for forming multiple contact openings within a film stack of a device according to embodiments of the present disclosure. [Figure 1E] This shows a side cross-sectional view of an exemplary method for forming multiple contact openings within a film stack of a device according to embodiments of the present disclosure. [Figure 1F] This shows a side cross-sectional view of an exemplary method for forming multiple contact openings within a film stack of a device according to embodiments of the present disclosure. [Figure 1G] This shows a side cross-sectional view of an exemplary method for forming multiple contact openings within a film stack of a device according to embodiments of the present disclosure. [Figure 1H]This shows a side cross-sectional view of an exemplary method for forming multiple contact openings within a film stack of a device according to embodiments of the present disclosure. [Figure 2A]

[0012] This shows a top view of a lithography mask formed on a film stack according to an embodiment of the present disclosure. [Figure 2B]

[0013] This shows a top view of a first set of contact openings formed in a film stack through an opening in a lithography mask according to an embodiment of the present disclosure. [Figure 2C]

[0014] This shows a top view of a second set of contact openings formed in a film stack through an opening in a lithography mask according to an embodiment of the present disclosure. [Figure 2D]

[0015] This shows a top view of an array of contact openings formed within a film laminate according to an embodiment of the present disclosure. [Figure 2E]

[0016] The image shows a top view of a series of lithography and etching processes for further etching a film stack according to embodiments of the present disclosure. [Figure 2F] The image shows a top view of a series of lithography and etching processes for further etching a film stack according to embodiments of the present disclosure. [Figure 2G] The image shows a top view of a series of lithography and etching processes for further etching a film stack according to embodiments of the present disclosure. [Figure 2H]

[0017] This shows a top view of an array of contact openings formed within a film laminate according to an embodiment of the present disclosure. [Figure 3A]

[0018] The image shows a top view of a series of lithography and etching processes for forming multiple contact openings according to embodiments of the present disclosure. [Figure 3B] The image shows a top view of a series of lithography and etching processes for forming multiple contact openings according to embodiments of the present disclosure. [Figure 3C]A top view of a series of lithography processes and etching processes for forming a plurality of contact openings according to an embodiment of the present disclosure is shown. [Figure 3D] A top view of a series of lithography processes and etching processes for forming a plurality of contact openings according to an embodiment of the present disclosure is shown. [Figure 3E] A top view of a series of lithography processes and etching processes for forming a plurality of contact openings according to an embodiment of the present disclosure is shown. [Figure 3F] A top view of a series of lithography processes and etching processes for forming a plurality of contact openings according to an embodiment of the present disclosure is shown. [Figure 4A]

[0019] A top view of a series of lithography processes and etching processes for forming a plurality of contact openings according to an embodiment of the present disclosure is shown. [Figure 4B] A top view of a series of lithography processes and etching processes for forming a plurality of contact openings according to an embodiment of the present disclosure is shown. [Figure 4C] A top view of a series of lithography processes and etching processes for forming a plurality of contact openings according to an embodiment of the present disclosure is shown. [Figure 4D] A top view of a series of lithography processes and etching processes for forming a plurality of contact openings according to an embodiment of the present disclosure is shown. [Figure 4E] A top view of a series of lithography processes and etching processes for forming a plurality of contact openings according to an embodiment of the present disclosure is shown. [Figure 5A]

[0020] A top view of a series of lithography processes and etching processes for forming a plurality of contact openings according to an embodiment of the present disclosure is shown. [Figure 5B] A top view of a series of lithography processes and etching processes for forming a plurality of contact openings according to an embodiment of the present disclosure is shown. [Figure 5C] The image shows a top view of a series of lithography and etching processes for forming multiple contact openings according to embodiments of the present disclosure. [Figure 5D] The image shows a top view of a series of lithography and etching processes for forming multiple contact openings according to embodiments of the present disclosure. [Figure 5E] The image shows a top view of a series of lithography and etching processes for forming multiple contact openings according to embodiments of the present disclosure. [Figure 6A]

[0021] The image shows a top view of a series of lithography and etching processes for forming multiple contact openings according to embodiments of the present disclosure. [Figure 6B] The image shows a top view of a series of lithography and etching processes for forming multiple contact openings according to embodiments of the present disclosure. [Figure 6C] The image shows a top view of a series of lithography and etching processes for forming multiple contact openings according to embodiments of the present disclosure. [Figure 6D] The image shows a top view of a series of lithography and etching processes for forming multiple contact openings according to embodiments of the present disclosure. [Figure 6E] The image shows a top view of a series of lithography and etching processes for forming multiple contact openings according to embodiments of the present disclosure. [Figure 7A]

[0022] This shows a side view of a plurality of contact openings formed within a film laminate according to an embodiment of the present disclosure. [Figure 7B]

[0023] This shows a side view of a liner formed within a plurality of contact openings formed in a film laminate according to an embodiment of the present disclosure. [Figure 7C]

[0024] This shows a side view of a film laminate after removing a plurality of second layers from the film laminate according to an embodiment of the present disclosure. [Figure 7D]

[0025] This shows a side view of a film laminate after multiple word lines have been formed according to an embodiment of the present disclosure. [Figure 7E]

[0026] This shows a side view of a film laminate after removing a portion of the liner from within a plurality of contact openings according to an embodiment of the present disclosure. [Figure 7F]

[0027] This shows a side view of a film laminate after multiple word line contacts have been formed according to an embodiment of the present disclosure. [Figure 8]

[0028] This is a schematic diagram of an exemplary system according to an embodiment of the present disclosure. [Figure 9]

[0029] The process flow of a method for forming an exemplary device according to embodiments of this disclosure is shown. [Modes for carrying out the invention]

[0012]

[0030] The drawings are not necessarily to scale. The drawings are for illustrative purposes only and are not intended to depict specific parameters of the disclosure. The drawings are intended to illustrate exemplary embodiments of the disclosure and should therefore not be considered limiting. In the drawings, similar numbering indicates similar elements.

[0013]

[0031] Furthermore, certain elements in some diagrams may be omitted or not shown to scale for the sake of clarity. Sectional views may be presented in the form of "slices" or "near-sighted" sections, where certain background lines that would be visible in a "true" section are omitted for visual clarity. Additionally, some reference numbers may be omitted in certain drawings for clarity.

[0014]

[0032] The methods, systems, and devices described herein will be described in more detail below with reference to the accompanying drawings illustrating various embodiments. These methods, systems, and devices may be embodied in many different forms and should not be construed as being limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure may be comprehensive and complete and so as to fully convey the scope of the methods to those skilled in the art.

[0015]

[0033] The embodiments described herein relate to a 3D NAND word line contact formation method, wherein a first series of alternating lithography and etching processes are performed on a film stack and a lithography mask to form an array of contact aperture pairs on the film stack. The apertures passing through the first lithography mask may be expanded in a first direction after each etching process so as to vary the depth of the array of contact aperture pairs in a first direction. The method may further include forming a second lithography mask (or more masks) on the film stack and performing a second series of alternating lithography and etching processes, wherein the apertures passing through the second lithography mask are expanded in a second direction after each etching process, thereby varying the depth of the array of contact aperture pairs in a second direction.

[0016]

[0034] As a result, embodiments of the present disclosure utilize a staircase and chop approach to group multiple direct word line contact holes in a stadium-like manner, which can advantageously reduce the number of photolithography steps, reduce the maximum delta-ON pair for better dry etching endpoint control, shorten the length of word line contacts, and minimize the impact on bit density.

[0017]

[0035] Figure 1A shows a side cross-sectional view of a memory device (hereinafter, "device") 100 in an early stage of processing according to one or more embodiments described herein. The device 100 may include a film stack 102 having a plurality of horizontal first layers 106 and second layers 108 stacked alternately on top of each other. The film stack 102 may be part of a memory cell device such as a three-dimensional (3D) memory device (e.g., NAND). The first layer 106 may be a dielectric material such as silicon oxide (SiO), and the second layer 108 may be a second dielectric material such as silicon nitride. In other embodiments, dielectric materials suitable for the first layer 106 and / or the second layer 108 may include, in particular, silicon oxynitride, silicon carbide, silicon oxycarbide, titanium nitride, oxide and nitride composites, at least one or more oxide layers sandwiching a nitride layer, and combinations thereof.

[0018]

[0036] As further illustrated, the film stack 102 may include a plurality of bottom layer channel holes 109 formed by etching and gap filling. The device 100 may include a hard mask 110 formed on the film stack 102. In some embodiments, the hard mask 110 is a layer of tungsten (W) formed directly on the top surface 111 of the film stack 102.

[0019]

[0037] As shown in Figure 1B, a photoresist mask 112 is then formed on the hard mask 110, and multiple hard mask openings 115 can be patterned (etched) through the photoresist mask 112 to expose the upper surface 114 of the hard mask 110.

[0020]

[0038] As shown in Figure 1C, the hard mask 110 can be etched through the hard mask opening 115 of the photoresist mask 112 to form a plurality of openings 117. As shown, the plurality of openings 117 can be selectively formed on the upper surface 111 of the film laminate 102.

[0021]

[0039] As shown in Figure 1D, the first photoresist mask 120 may be formed on the device 100 without subsequently being formed on a portion 121 of the hard mask 110 or on an opening 115A.

[0022]

[0040] As shown in Figure 1E, device 100 may then be processed (e.g., etched) to form a first contact opening 122A in the film laminate 102. The first contact opening 122A may be formed below the opening 115A of the hard mask 110.

[0023]

[0041] As shown in Figure 1F, the first photoresist mask 120 then indents laterally (e.g., horizontally), exposing the opening 115B of the hard mask 110, and a second contact opening 122B may be formed within the film stack 102. As illustrated, the first contact opening 122A is further etched simultaneously with the second contact opening 122B, resulting in an increased etching depth. This “staircase” process continues as shown in Figures 1G to 1H, forming additional contact openings 122C and 122D in the film stack 102. It will be understood that the number of contact openings is not a definitive factor and can be increased or decreased as needed, depending on the number of first layers 106 and second layers 108 within the film stack 102.

[0024]

[0042] Figure 2A shows a top view of another device 200 in an early stage of processing according to one or more embodiments described herein. As will be described below, device 200 may be processed using a stepwise method similar to the method described above with respect to Figures 1A-1H. Device 200 may include a film stack 202 having a plurality of horizontal first and second layers stacked alternately on top of each other. The film stack 202 may be part of a memory cell device such as a three-dimensional (3D) memory device (e.g., NAND).

[0025]

[0043] Device 200 is illustrated as a grid or array 205 of landing pads 210. In the illustrated, non-limiting embodiments, array 205 includes a total of 240 landing pads (120 pairs of landing pads) in 10 rows and 24 columns. As illustrated, array 205 may be defined by a perimeter including a first main surface 212 and a second main surface 214 on the opposite side, as well as a first end 216 and a second end 218 on the opposite side. A central axis "CA" may extend between the first end 216 and the second end 218, but generally divides array 205 into a first side and a second side.

[0026]

[0044] As shown in the figure, a first lithography mask 220 may be formed on the array 205. Although not shown, the first lithography mask 220 may be formed on a patterned hard mask, similar to the hard mask 110 described above. The patterned hard mask may define target etching regions for a plurality of contact openings to be formed thereafter.

[0027]

[0045] In Figure 2B, an opening 222 may be formed through the first lithography mask 220. The opening 222 may extend between the first end 216 and the second end 218 of the array 205 and be formed on the opposite side of the central axis. The opening 222 may expose the first plurality of landing pads 210A. Etching may then be performed through the opening 222 to form the first plurality of contact openings 224A in the film laminate 202. In the illustrated example, 48 contact openings (24 pairs) are formed, with each contact opening pair separated by the central axis. In some embodiments, each of the first plurality of contact openings 224A may be formed to the same depth.

[0028]

[0046] As shown in Figure 2C, the opening 222 may then be expanded (e.g., etched) in a first direction (e.g., perpendicular to the central axis) to expose a second plurality of landing pads 210B. The second plurality of landing pads 210B may be directly adjacent to the first plurality of landing pads 210A. More specifically, a first row of the second plurality of landing pads 210B may be located along the first side of the first plurality of landing pads 210A, while a second row of the second plurality of landing pads 210B may be located along the second side of the first plurality of landing pads 210A. Another etching process may then be performed through the expanded opening 222 to form a second plurality of contact openings 224B in the film laminate 202. In the illustrated example, 48 contact openings (24 pairs) are formed, and each contact opening pair of the second plurality of contact openings 224B is divided by a central axis and by the first plurality of contact openings 224A. In some embodiments, each of the second plurality of contact openings 224B may be formed to the same depth. While the second plurality of contact openings 224B are being formed, the first plurality of contact openings 224A may be further etched, so that the etching depth of the first plurality of contact openings 224A is greater than the etching depth of the second plurality of contact openings 224B.

[0029]

[0047] This series of lithography and etching processes is repeated until a desired number of contact openings are formed, for example, the device 200 shown in Figure 2D. The array 205 may include a first plurality of contact openings 224A, a second plurality of contact openings 224B, a third plurality of contact openings 224C, a fourth plurality of contact openings 224D, and a fifth plurality of contact openings 224E. The depth of each contact opening in the third plurality of contact openings 224D may be the same, the depth of each contact opening in the fourth plurality of contact openings 224D may be the same, and the depth of each contact opening in the fifth plurality of contact openings 224E may be the same. In the illustrated embodiment, the depth of the contact openings in the array 205 varies along a first direction. More specifically, the depth of the contact openings may be maximum in the portion directly adjacent to the central axis and decrease toward the first principal surface 212 and the second principal surface 214, respectively. For example, the first etching depth of the first set of contact openings 224A is greater than the second etching depth of the second set of contact openings 224B, the second etching depth is greater than the third etching depth of the third set of contact openings 224C, the third etching depth is greater than the fourth etching depth of the fourth set of contact openings 224D, and the fourth etching depth is greater than the fifth etching depth of the fifth set of contact openings 224E.

[0030]

[0048] Figures 2E to 2H illustrate a method for performing a second series of alternating lithography and etching processes on a second lithography mask 230 and a film laminate 202 according to embodiments of the present disclosure. As will be described later, the openings through the second lithography mask 230 are progressively expanded in a second direction (e.g., along the central axis) following each etching step.

[0031]

[0049] First, as shown in Figure 2E, a second lithography mask 230 is formed on the array 205, and etching may be performed on the exposed first subset 234 of each of the first plurality of contact openings 224A, second plurality of contact openings 224B, third plurality of contact openings 224C, fourth plurality of contact openings 224D, and fifth plurality of contact openings 224E. The first subset 234 may correspond to a row directly adjacent to the first end 216 of the array 205. As a result of etching, the depth of each contact opening in the first subset 234 increases. However, because the second lithography mask 230 is present, the rest of the array 205 is not etched.

[0032]

[0050] As shown in Figure 2F, the second lithography mask 230 may be partially recessed or laterally removed to expose the second subset 235 of each of the first plurality of contact openings 224A, the second plurality of contact openings 224B, the third plurality of contact openings 224C, the fourth plurality of contact openings 224D, and the fifth plurality of contact openings 224E. The second subset 235 may correspond to a second row directly adjacent to the first subset 234 of the array 205. As a result of etching, the depth of each contact opening in the first subset 234 and the second subset 235 is increased. In this embodiment, the average depth of each contact opening in the first subset 234 is greater than the average depth of each contact opening in the second subset 235.

[0033]

[0051] As shown in Figure 2G, the second lithography mask 230 may again be partially recessed or removed to expose the third subset 236 of each of the first plurality of contact openings 224A, the second plurality of contact openings 224B, the third plurality of contact openings 224C, the fourth plurality of contact openings 224D, and the fifth plurality of contact openings 224E, each of which has a fifth etching depth. The third subset 236 may correspond to a third column of the array 205 that is directly adjacent to the second subset 235. As a result of etching, the depth of each contact opening in the first subset 234, the second subset 235, and the third subset 236 increases. In this embodiment, the average depth of each contact opening in the first subset 234 is greater than the average depth of each contact opening in the second subset 235, and the average depth of each contact opening in the second subset 235 is greater than the average depth of each contact opening in the third subset 236.

[0034]

[0052] This second series of alternating lithography and etching processes may continue until the device 200 shown in Figure 2H is realized. As illustrated, non-limiting numerical depth values ​​of the contact openings are provided for each landing pad 210 to indicate the depth variation across the array 205. For example, the first subset 234 has contact opening depth values ​​in the range of 116 to 120, while the second subset 235 has contact opening depth values ​​in the range of 111 to 115. As shown, each contact opening in the first subset 234 may have a greater depth than each contact opening in the second subset 235. On the other hand, the subset 239 directly adjacent to the second end 218 of the array 205 may have contact opening depth values ​​in the range of 1 to 5. In this embodiment, subset 239 may be etched only during the first series of alternating lithography and etching processes shown in Figures 2A to 2D. Once etching is complete, the depth of the contact openings in array 205 generally decreases between the first end 216 and the second end 218, and increases toward the central axis. Advantageously, the stepped technique shown in Figures 2A–2H reduces the number of lithography and etching passes from 24 to 15.

[0035]

[0053] Referring here to Figure 3A, another method for forming the device 300 according to embodiments of the present disclosure is shown. The device 300 may be initially processed using the method described above and shown in Figures 2A to 2D. The device 300 may include a film stack 302 having a plurality of horizontal first and second layers stacked alternately on top of each other. The film stack 302 may be part of a memory cell device such as a three-dimensional (3D) memory device (e.g., NAND).

[0036]

[0054] For the sake of simplification, individual landing pads and contact openings are not shown, but the film laminate 302 may include an array 305 of a first plurality of contact openings 324A, a second plurality of contact openings 324B, a third plurality of contact openings 324C, a fourth plurality of contact openings 324D, and a fifth plurality of contact openings 324E. In the illustrated embodiment, the first etching depth of the first plurality of contact openings 324A is greater than the second etching depth of the second plurality of contact openings 324B, the second etching depth is greater than the third etching depth of the third plurality of contact openings 324C, the third etching depth is greater than the fourth etching depth of the fourth plurality of contact openings 324D, and the fourth etching depth is greater than the fifth etching depth of the fifth plurality of contact openings 324E.

[0037]

[0055] Device 300 may include a plurality of target etching regions 338A to 338D. These regions are separated by a plurality of etch-free regions 339A to 339C. Although not shown, a first lithography mask may be formed on the array 305 (including over each of the plurality of target etching regions 338A to 338D and over each of the plurality of etch-free regions 339A to 339C). A series of lithography and etching processes are then performed to form an opening 342A through the first lithography mask to expose the upper surface of the film stack 302. Subsequent etching may increase the depth of these contact openings exposed by the opening 342A. More specifically, etching may further process the first subset 348A of each of the first plurality of contact openings 324A, second plurality of contact openings 324B, third plurality of contact openings 324C, fourth plurality of contact openings 324D, and fifth plurality of contact openings 324E.

[0038]

[0056] Next, each of the openings 342A may be extended to form an opening 342B for each of the multiple target etching regions 338A to 338D. Subsequent etching may increase the depth of these contact openings exposed by the openings 342B. More specifically, etching may further process a second subset 348B of each of the first multiple contact openings 324A, the second multiple contact openings 324B, the third multiple contact openings 324C, the fourth multiple contact openings 324D, and the fifth multiple contact openings 324E. The first subset 348A may also be further processed together with the second subset 348B.

[0039]

[0057] Similarly, each of the openings 342B may then be extended to form an opening 342C for each of the multiple target etching regions 338A to 338D. Subsequent etching may increase the depth of these contact openings exposed by the openings 342C. More specifically, etching may further process a third subset 348C of each of the first multiple contact openings 324A, the second multiple contact openings 324B, the third multiple contact openings 324C, the fourth multiple contact openings 324D, and the fifth multiple contact openings 324E. The first subset 348A and the second subset 348B may be further processed together with the third subset 348C.

[0040]

[0058] This series of lithography and etching processes may be repeated as needed to obtain, for example, the device 300 shown in Figure 3B. At this stage, the contact openings of the array 305 may be characterized by a series of deeper sections 350A to 350D separated by etching-free regions 339A to 339C. In this embodiment, the deeper sections 350A to 350D generally correspond to these contact openings of a first subset 348A directly adjacent to the central axis.

[0041]

[0059] Next, as shown in Figure 3C, a second lithography mask 352 (or more masks) may be formed on a selected portion of the array 305. For example, the second lithography mask 352 may be formed on the second target etching region 338B and the fourth target etching region 338D, but not on the first target etching region 338A and the third target etching region 338C. In some embodiments, the second lithography mask 352 may be partially formed on the etching-free regions 339A-339C. Subsequently, an etching process may be performed on the exposed portions 356, 357 of the array 305 to further increase the etching depth of the contact openings in these regions.

[0042]

[0060] Next, as shown in Figure 3D, a third lithography mask 358 (or more masks) may be formed on a selected portion of the array 305. For example, the third lithography mask 358 may be formed on the first target etching region 338A, the third target etching region 338C, and the fourth target etching region 338D. However, the second target etching region 338B remains uncovered by the third lithography mask 358. Subsequently, an etching process may be performed on the exposed portion 359 of the array 305 to further increase the etching depth of the contact openings in this region.

[0043]

[0061] Similarly, as shown in Figure 3E, a fourth lithography mask 360 may be formed on a selected portion of the array 305. For example, the fourth lithography mask 360 may be formed over the second target etching region 338B, the third target etching region 338C, and the fourth target etching region 338D. However, the first target etching region 338A remains uncovered by the fourth lithography mask 360. Subsequently, an etching process may be performed on the exposed portion 362 of the array 305 to further increase the etching depth of the contact openings in this region.

[0044]

[0062] This second series of alternating lithography and etching processes may continue until the device 300 shown in Figure 3F is realized. As illustrated, each target etching region 338A-338D is separated by etching-free regions 339A-339C. In the illustrated embodiment, the average etching depth of the contact openings in the first target etching region 338A is greater than that of the second target etching region 338B, the average etching depth of the contact openings in the second target etching region 338B is greater than that of the third target etching region 338C, and the average etching depth of the contact openings in the third target etching region 338C is greater than that of the fourth target etching region 338D. Although not limited, etching-free region 339A corresponds to columns 364A-364B, etching-free region 339B corresponds to columns 364A-364B, while etching-free region 339C corresponds to columns 366A-366C. Upon completion of etching, the depth of the contact openings within each target etching region 338A-338D generally increases toward the center 367 of each target etching region 338A-338D. Advantageously, the direct wordline contact-first staircase+chop approach, shown in Figures 3A-3F, can reduce the number of lithography and etching passes from 24 to 18 and the maximum delta pairs from 114 to 29.

[0045]

[0063] Referring here to Figure 4A, another method for forming the device 400 according to embodiments of the present disclosure is shown. The device 400 may be initially processed using the method described above and shown in Figures 2A to 2D. The device 400 may include a film stack 402 having a plurality of horizontal first and second layers stacked alternately on top of each other. The film stack 402 may be part of a memory cell device such as a three-dimensional (3D) memory device (e.g., NAND).

[0046]

[0064] For the sake of simplification, individual landing pads and contact openings are not shown, but the film laminate 402 may include an array 405 of a first plurality of contact openings 424A, a second plurality of contact openings 424B, a third plurality of contact openings 424C, a fourth plurality of contact openings 424D, and a fifth plurality of contact openings 424E. In the illustrated embodiment, the first etching depth of the first plurality of contact openings 424A is greater than the second etching depth of the second plurality of contact openings 424B, the second etching depth is greater than the third etching depth of the third plurality of contact openings 424C, the third etching depth is greater than the fourth etching depth of the fourth plurality of contact openings 424D, and the fourth etching depth is greater than the fifth etching depth of the fifth plurality of contact openings 424E.

[0047]

[0065] Device 400 may include a plurality of target etching regions 438A to 438B. These regions are separated by etching-free regions 439 (not shown), but a first lithography mask may be formed on array 405 (including over each of the plurality of target etching regions 438A to 438B and over the etching-free regions 439). A series of lithography and etching processes may then be performed as described above and shown in Figure 3A. This will form a series of ever-expanding openings 442A to 442E through the first lithography mask, exposing the upper surface of the film laminate 402. A series of etching processes performed between each opening expansion stage may increase the depth of the contact openings exposed by openings 442A to 442E.

[0048]

[0066] This series of lithography and etching processes may be repeated as needed to obtain, for example, the device 400 shown in Figure 4B. As illustrated, the contact openings of array 405 may be characterized by a series of deeper sections 450A, 450B separated by etching-free regions 439. The deeper sections 450A generally correspond to an adjacent pair of first columns 444A, 444B of array 405, while the deeper sections 450B generally correspond to an adjacent pair of second columns 445A, 444B of array 405. The depth of the contact openings of the adjacent pair of first columns 444A, 445B increases toward the central axis. Similarly, the depth of the contact openings of the adjacent pair of second columns 445A, 445B increases toward the central axis. In this embodiment, the etching-free regions 439 may correspond to columns 447A-447D.

[0049]

[0067] As shown in Figure 4C, a second lithography mask 452 (or more masks) may be formed on a selected portion of the array 405. For example, the second lithography mask 452 may be formed on only a portion of each of the deeper sections 450A, 450B. More specifically, the second lithography mask 452 may be formed between column 444B of the deeper section 450A and column 447C of the etching-free region 439. However, the region 470 between the first end 416 of the array 405 and the first column 444A of the deeper section 450A is not covered by the second lithography mask 452. On the other hand, the second lithography mask 452 may be further formed on the array 405 between the second column 445B of the deeper section 450B and the second end 418 of the array 405. As shown in the figure, the second lithography mask 452 may not cover the region 472 between the first column 447D of the etching-free region 439 and the deeper section 450B of the first column 445A. Subsequently, an etching process may be performed on the exposed regions 470, 472 of the array 405 to further increase the etching depth of the contact openings in these regions.

[0050]

[0068] Next, as shown in Figure 4D, a third lithography mask 458 may be formed over a selected portion of the array 405. For example, the third lithography mask 458 may be formed over a deeper section 450B and a portion of the etching-free region 439. More specifically, the third lithography mask 458 may extend from the second end 418 of the array 405 to column 447B of the etching-free region 439. However, the deeper section 450A remains uncovered by the third lithography mask 458. Subsequently, an etching process may be performed on the exposed region 475 of the array 405 to further increase the etching depth of the contact openings in this region. As shown, the exposed region 475 may extend from the first end 416 of the array 405 to column 447A of the etching-free region 439.

[0051]

[0069] Following a series of alternating lithography and etching processes, the device 400 shown in Figure 4E is realized. As illustrated, the depth of the contact openings in each of the deeper sections 450A, 450B generally increases toward their center 467. However, the average depth of the contact openings in column 476 directly adjacent to the first end 416 of array 405 is greater than the average depth of the contact openings in column 446 directly adjacent to column 447A of the etching-free region 439. Similarly, the average depth of the contact openings in column 449 directly adjacent to column 447B of the etching-free region 439 is greater than the average depth of the contact openings in column 478 closer to the second end 418 of array 405. In this embodiment, column 479 may also represent an etching-free region of array 405. Advantageously, the direct word line contact-first staircase + chop method shown in Figures 4A to 4E can reduce the number of lithography and etching passes from 24 to 15 and shorten the contact length from 150 to 78 (for example, assuming 3 tiers, ON360 pairs, and a block width of 5 μm).

[0052]

[0070] Referring here to Figure 5A, another method for forming the device 500 according to embodiments of the present disclosure is shown. The device 500 may be initially processed using the method described above and shown in Figures 2A to 2D. The device 500 may be further processed using the method described above and shown in Figure 3A. As illustrated, the device 500 may include an array 505 containing a series of alternately arranged deeper sections 550A to 550L and contact openings processed to form an etching-free region 539.

[0053]

[0071] A lithography mask (not shown) may be formed on the array 505 of device 500. Then, multiple openings 515 may be formed to expose a portion of the array 505. Subsequently, the exposed portion of the array 505 is etched to increase the depth of the affected contact openings. In this process, all other deeper portions (e.g., 550B, 550D, etc.) may be etched.

[0054]

[0072] As shown in Figure 5B, array 505 is subjected to a series of additional lithography and etching steps to form multiple openings 517 through a lithography mask (not shown) to further increase the depth of the affected contact openings. As illustrated, deeper sections 550C, 550D, 550G, 550H, 550K, and 550L are etched. More specifically, each time a deeper section 550C, 550G, or 550K is etched, a deeper section 550D, 550H, or 550L may be etched twice.

[0055]

[0073] As shown in Figure 5C, array 505 is subjected to a series of additional lithography and etching steps to form multiple openings 519 through a lithography mask (not shown) to further increase the depth of the affected contact openings. As illustrated, portions of the deeper sections 550E–550L are etched in a range of 1–4 passes.

[0056]

[0074] As shown in Figure 5D, the array 505 is subjected to a series of additional lithography and etching steps to form multiple openings 521 through a lithography mask (not shown) to further increase the depth of the affected contact openings. As shown, some deeper sections 550I–550L are etched in a range of 1–4 passes, resulting in the device 500 shown in Figure 5E. As shown, the average depth of the contact openings in the deeper section 550L is the largest in the array 505. Generally, the depth of the contact openings in the array increases between the first end 516 and the second end 518 of the array 505. Furthermore, the depth of the contact openings in each of the deeper sections 550A–550L increases toward their center 567. Advantageously, the direct wordline contact-last staircase+chop approach shown in Figures 5A–5E can reduce the maximum number of delta pairs from 116 to 29.

[0057]

[0075] Referring here to Figure 6A, another method for forming device 600 according to embodiments of the present disclosure is shown. Device 600 may be initially processed using the method described above and shown in Figures 2A to 2D. Device 500 may be further processed using the method described above and shown in Figure 3A. As illustrated, device 600 may include an array 605 containing a series of alternately arranged deeper sections 650A to 650F and contact openings processed to form etching-free regions 639.

[0058]

[0076] A lithography mask (not shown) may be formed on the array 605 of device 600. Then, multiple openings 615 may be formed to expose a portion of the array 605. Subsequently, the exposed portion of the array 605 is etched to increase the depth of the affected contact openings. In this process, each opening 615 may expose a portion of each of the deeper sections 650A-650F and a portion of each etching-free region 639. In other words, each opening 615 may be offset relative to the corresponding deeper sections 650A-650F.

[0059]

[0077] As shown in Figure 6B, array 605 is subjected to a series of additional lithography and etching steps. Here, multiple openings 617 are formed through a lithography mask (not shown), further increasing the depth of the affected contact openings. As shown, deeper sections 650B, 650D, and 650F are located in the center below the openings 617 and are then etched.

[0060]

[0078] As shown in Figure 6C, array 605 is subjected to a series of additional lithography and etching steps to form multiple openings 619 through a lithography mask (not shown) to further increase the depth of the affected contact openings. As shown, the deeper sections 650C–650F are etched one–two times, while the deeper sections 650A and 650B remain unaffected in this process.

[0061]

[0079] As shown in Figure 6D, the array 605 is subjected to a series of additional lithography and etching steps to form multiple openings 621 through a lithography mask (not shown) to further increase the depth of the affected contact openings. As shown, the deeper sections 650E and 650F are etched to obtain the device 500 shown in Figure 6E. As shown, the average depth of the contact openings in the deeper section 650F is the largest in the array 605. Generally, the depth of the contact openings in the array 605 increases between the first end 616 and the second end 618 of the array 605. Furthermore, the depth of the contact openings in each of the deeper sections 650A to 650F increases toward their center 667. Advantageously, the step-and-chop technique with direct word line contacts after the initial step, as shown in Figures 6A to 6E, can reduce the maximum delta pairs from 116 to 59, the number of lithography passes from 10 to 9, and shorten the contact length from 152 μm to 82 μm (for example, assuming 3 tiers, ON360 pairs, and a block width of 5 μm).

[0062]

[0080] After the contact openings described in one or more embodiments above are completed, non-limiting processes shown in Figures 7A to 7F may be performed to form multiple word lines within the device. As shown in Figure 7A, the device 700 may include a film laminate 702 having a plurality of first layers 706 and a plurality of second layers 708 arranged alternately therewith. As shown in Figure 7B, sacrificial gap fill may be removed from one or more of the contact openings 725, such as the four deepest contact openings, and then a liner 740 may be formed on the device 700, including the interior of each of the contact openings 725. In some embodiments, the liner 740 may be an oxide layer (e.g., SiO, AlO, etc.). This oxide layer is formed along all exposed surfaces of the device 700 (e.g., via atomic layer deposition (ALD)).

[0063]

[0081] As shown in Figure 7C, the second layer 708 of the film laminate 702 is removed, for example, by a horizontal wet etching process, forming multiple word line openings 750 in the device 700. The first layer 706, generally like the liner 740, is unaffected by wet etching and remains within the contact openings 725.

[0064]

[0082] Next, by depositing a first conductive material (e.g., tungsten (W) or molybdenum (Mo)) within the multiple word line openings 750, multiple word lines 752 may be formed within the device 700, as shown in Figure 7D. Subsequently, as shown in Figure 7E, the liner 740 may be removed from the bottom of the contact opening 725. In some embodiments, the liner 740 may be etched vertically to expose the upper surfaces of one or more of the multiple word lines 752. As shown, the liner 740 remains along the sidewalls of the contact opening 725. In some embodiments, the liner 740 is also removed from the upper surface of the second film laminate 702.

[0065]

[0083] As shown in Figure 7F, the second conductive material 760 may be deposited within the contact opening 725 to form a plurality of word line contacts 762. In some embodiments, the second conductive material 760 may be tungsten, for example, deposited on the upper surface of a plurality of word lines 752 together with titanium nitride (TiN) via atomic layer deposition. The second conductive material 760 may be separated from the first layer 706 by a liner 740 along the sidewall of the contact opening 725. In some embodiments, due to the aspect ratio of these contact openings 725, voids 757 of the second conductive material 760 may exist within one or more of the word line contacts 762.

[0066]

[0084] Figure 8 shows a schematic diagram of an exemplary system / apparatus 800 according to embodiments of the present disclosure. The operation of system 800 will be described with reference to devices 100-700 described herein. In some embodiments, system 800 may be a cluster tool capable of performing the processes necessary to form a device. Not limited to, system 800 may include at least one central transfer station / chamber 802 and one or more robots 804 within the transfer station / chamber 802. The robots 804 are connected to the transfer station / chamber 802 or are capable of moving robot blades and wafers between each of a plurality of processing chambers 810A-810N located adjacent to the transfer station / chamber 802. In some embodiments, system 800 may include, but is not limited to, a variety of suitable chambers including a first deposition chamber 810A, a first etching chamber 810B, a second deposition chamber 810C, a second etching chamber 810D, and a third deposition chamber 810E. The first deposition chamber 810A, the second deposition chamber 810C, and the third deposition chamber 810E may include one or more atomic layer deposition chambers, plasma-enhanced atomic layer deposition chambers, chemical vapor deposition chambers, plasma-enhanced chemical vapor deposition chambers, or physical deposition chambers. The specific arrangement of the processing chambers and components is modifiable depending on the cluster tool and should not be considered to limit the scope of this disclosure. For example, in an alternative embodiment, only a single deposition chamber and / or only a single etching chamber may be present in the system 800. In another example, one or more deposition chambers may include multiple process regions within the same chamber. This allows for common gas supply, common pressure control, and common process gas exhaust / pumping. The modular design of the system allows for rapid conversion from one configuration to any other configuration.

[0067]

[0085] In some embodiments, the first deposition chamber 810A may be used to deposit the film stacks 102-702 as alternating first and second layers. The first deposition chamber 810A may be further used to deposit multiple masking and lithography layers.

[0068]

[0086] The first etching chamber 810B may be used to etch multiple masking layers and form multiple contact openings in devices 100-700. The first etching chamber 810B may be further used to punch through the liner 740 along the bottom of each contact opening 725 of device 700.

[0069]

[0087] A second deposition chamber 810C may be used to deposit the liner 740 onto the device 700 (including within each contact opening 725) and to deposit sacrificial gap fill within multiple contact openings 725.

[0070]

[0088] A second etching chamber 810D may be used to remove the first layer 706 and form a plurality of word line openings 750 in the film laminate 703. In some embodiments, a wet etching process may be performed in the second etching chamber 810D.

[0071]

[0089] A third deposition chamber 810E may be used to form multiple word lines 752 by depositing a first conductive material 754 within multiple word line openings 750. The third deposition chamber 810E (or another deposition chamber) may be further used to deposit a second conductive material 760 within multiple contact openings 725 to form multiple word line contacts 762 within the device 700.

[0072]

[0090] The system controller 820 communicates with the robot 404, the transfer station / chamber 802, and the multiple processing chambers 810A-810E. The system controller 820 can be any suitable component that can control the processing chambers 810A-810E and one or more robots 804, as well as the processes that take place within the processing chambers 810A-810E. For example, the system controller 820 may be a computer including a central processor 822, memory 824, appropriate circuits / logic / instructions, and storage.

[0073]

[0091] A process or instruction, when executed by processor 822, can generally be stored in the memory 824 of system controller 820 as a software routine that causes processing chambers 810A-810N to execute the process of this disclosure. The software routine may also be stored and / or executed by a second processor (not shown) located remotely from the hardware controlled by processor 822. Some or all of one or more methods of this disclosure may be executed in hardware. Thus, a process can be implemented in software and executed in hardware using a computer system, for example, as an application-specific integrated circuit or other type of hardware implementation, or as a combination of software and hardware. When executed by processor 822, the software routine transforms a general-purpose computer into an application-specific computer (controller) that controls the chamber operation so that the process can be executed.

[0074]

[0092] Referring now to Figure 9, a process 900 according to an embodiment of the present disclosure is shown. In block 901, the process 900 may include providing a film laminate comprising a plurality of alternating first and second layers. A film laminate comprising a plurality of alternating first and second layers is provided. In some embodiments, the first layer of the plurality of alternating first and second layers is a dielectric material, and the second layer of the plurality of alternating first and second layers is a dielectric material or a conductive material. In some embodiments, the first layer of the alternating first and second layers is silicon oxide, and the second layer of the plurality of alternating first and second layers is silicon nitride.

[0075]

[0093] In block 902, process 900 may include forming a first lithography mask on a film stack. In some embodiments, a hard mask may first be formed on the film stack. In some embodiments, the hard mask is a layer of tungsten formed directly on the upper surface of the film stack. In some embodiments, a photoresist mask is then formed on the hard mask, and a plurality of hard mask openings may be patterned (etched) through the photoresist mask to expose the upper surface of the hard mask. In some embodiments, the hard mask may then be etched through the hard mask openings of the photoresist mask to form a plurality of openings. In some embodiments, the first photoresist mask may then be formed on the device without being formed on any part of the hard mask or any part of the openings.

[0076]

[0094] In block 903, process 900 may further include performing a first series of alternating lithography and etching processes on a first lithography mask and a film laminate to form an array of contact aperture pairs in the film laminate. Here, the apertures through the first lithography mask are expanded in a first direction after each etching process, and the depth of the array of contact aperture pairs is varied in the first direction.

[0077]

[0095] In block 904, process 900 may further include forming a second lithography mask on the film stack.

[0078]

[0096] In block 905, process 900 may further include performing a second series of alternating lithography and etching processes on a second lithography mask and film stack. Here, the openings through the second lithography mask are expanded in a second direction after each etching process of the second series of alternating lithography and etching processes, and the depth of the array of contact opening pairs is varied in the second direction.

[0079]

[0097] In block 906, process 900 may further include depositing a liner and removing the first layer to form a plurality of word line openings in the film stack. In some embodiments, the first layer is removed using a horizontal wet etching process that selectively removes the first layer without removing the second layer.

[0080]

[0098] In block 907, process 900 may further include forming multiple word lines by depositing a first conductive material within multiple word line openings. In some embodiments, the first conductive material is W or Mo.

[0081]

[0099] In block 908, process 900 may include removing the liner from the bottom of each contact opening of a plurality of contact openings. In some embodiments, removing the liner from the bottom of each contact opening of a first plurality of contact openings and a second plurality of contact openings exposes the upper surface of one or more word lines of a plurality of word lines. In some embodiments, the liner is removed from the bottom of each contact opening of a first plurality of contact openings and a second plurality of contact openings without removing the liner from the side walls of each contact opening of a first plurality of contact openings and a second plurality of contact openings.

[0082]

[0100] In block 909, process 900 may include depositing a second conductive material within a first plurality of contact openings and a second plurality of contact openings to form a plurality of word line contacts. In some embodiments, the second conductive material may be W deposited together with TiN on the upper surface of the plurality of word lines.

[0083]

[0101] In various embodiments, a design tool may be provided and configured to create a dataset used for patterning semiconductor layers of a device, for example, as described herein. For example, the dataset may be created to generate a photomask used in a lithography process for patterning layers for a structure such as described herein. Such a design tool may include a collection of one or more modules, which may consist of hardware, software, or a combination thereof. Thus, for example, the tool may be a collection of one or more software modules, hardware modules, software / hardware modules, or any combination or arrangement thereof. As another example, the tool may be implemented in hardware, or it may be a computing device or other appliance that runs the software.

[0084]

[0102] For convenience and clarity, terms such as “top,” “bottom,” “up,” “down,” “vertical,” “horizontal,” “lateral,” and “longitudinal” will be used herein to describe the components appearing in the figures and the relative arrangement and orientation of their components. Technical terms will include the words specifically mentioned, their derivatives, and words with similar meanings.

[0085]

[0103] Where used herein, an element or action described in the singular form beginning with the word "a" or "an" should be understood to include multiple elements or actions unless explicitly stated to exclude them. Furthermore, references to "one embodiment" in this disclosure are not intended to be limiting. Additional embodiments may also incorporate the described features.

[0086]

[0104] Furthermore, the terms “substantial” or “substantially,” in addition to “approximate” or “approximately,” can be used interchangeably in some embodiments and can be described using any relative scale acceptable to those skilled in the art. For example, these terms can serve as a comparison to a reference parameter to indicate a deviation that can provide the intended function. Although not restrictive, the deviation from the reference parameter could be, for example, less than 1%, less than 3%, less than 5%, less than 10%, less than 15%, less than 20%, etc.

[0087]

[0105] Furthermore, when it is stated that an element such as a layer, region, or substrate is formed, deposited, or placed "on / over / atop" another element, a person skilled in the art will understand that the element may be in direct contact with the other element, or there may be an intervening element. In contrast, when it is stated that an element is "directly on / directly over / directly atop" another element, there is no intervening element.

[0088]

[0106] The scope of this disclosure should not be limited by the specific embodiments described herein. In fact, from the above description and accompanying drawings, a variety of other embodiments and modifications of this disclosure, in addition to those described herein, will be obvious to those skilled in the art. Thus, such other embodiments and modifications are intended to be included within the scope of this disclosure. Furthermore, this disclosure has been described in light of specific embodiments in specific environments for specific purposes. Those skilled in the art will recognize that these specific embodiments are not the only useful, and that this disclosure can be advantageously implemented for any number of purposes in any number of environments. Accordingly, the claims described below should be interpreted in light of the entire scope and spirit of this disclosure as described herein.

Claims

1. Forming a first lithography mask on a film laminate containing alternatingly arranged first and second layers, Forming an array of contact aperture pairs within the film laminate, wherein, following each etching process of a first series of alternating lithography and etching processes, the apertures passing through the first lithography mask are expanded in a first direction, and the depth of the array of contact aperture pairs changes in the first direction, Forming an opening through a second lithography mask formed on the film laminate, wherein, following each etching process of a second series of alternating lithography and etching processes, the opening expands in a second direction and the depth of the array of contact opening pairs changes in the second direction. Methods that include...

2. The film laminate is defined by a first main surface and a second main surface on the opposite side, and by a first end and a second end on the opposite side. The method according to claim 1, further comprising: a central axis extending in a second direction between the first end and the second end, the first contact opening of each contact opening pair in the array of contact opening pairs being located on the first side of the central axis, and the second contact opening of each contact opening pair in the array of contact opening pairs being located on the second side of the central axis.

3. The method according to claim 2, wherein forming the array of contact opening pairs involves etching the first contact opening of each contact opening pair in the array of contact opening pairs such that each contact opening pair in the array of contact opening pairs has the same depth as the corresponding second contact opening of each contact opening pair in the array of contact opening pairs.

4. The method according to claim 2, wherein the depth of the array of contact opening pairs in the first direction is maximized in the portion directly adjacent to the central axis.

5. After performing the second series of alternating lithography and etching processes, the gap fill is removed from one or more contact openings of the array of contact opening pairs. After removing the gap fill from one or more contact openings, a liner is formed in each contact opening of the array of contact opening pairs. In order to form a plurality of word line openings within the aforementioned film laminate, the first layer is removed, By depositing the first conductive material within the plurality of word line openings, a plurality of word lines are formed. Removing the liner from the bottom of each contact opening in the array of the contact opening pairs, To form multiple word line contacts, a second conductive material is deposited within the array of the contact aperture pairs. The method according to claim 1, further comprising:

6. A method for forming a 3D NAND device, The method involves forming a patterned hard mask and a first lithography mask on a film laminate, wherein the film laminate comprises a plurality of alternately arranged first and second layers, forming the patterned hard mask and the first lithography mask. To form a first set of contact openings within the film stack, the film stack is etched through the openings of the first lithography mask, Expanding the opening of the first lithography mask in the first direction, Etching the film laminate through the openings of the first lithography mask in order to form a second plurality of contact openings within the film laminate, wherein the depth of the first plurality of contact openings increases as the second plurality of contact openings are formed. To increase the depth of the first subset of contact openings and the second subset of contact openings, the film laminate is etched through the openings of a second lithography mask formed on the film laminate, Etching the film laminate through the openings of the second lithography mask in order to increase the depth of the second subset of the first plurality of contact openings and the second subset of the second plurality of contact openings, wherein the depth of the first plurality of contact openings and the second plurality of contact openings changes in the first and second directions. Methods that include...

7. The method according to claim 6, further comprising increasing the depth of the subset of the first plurality of contact openings and the depth of the subset of the second plurality of contact openings as the depth of the subset of the second plurality of contact openings increases.

8. The third lithography mask is formed on the film laminate, wherein the third lithography mask has a plurality of openings for exposing a first plurality of contact openings and one or more first portions of a second plurality of contact openings. To further increase the etching depth of the first plurality of contact openings and the first plurality of contact openings, and the first or more first portions of the second plurality of contact openings, the film laminate is etched through the plurality of openings of the third lithography mask. The method according to claim 6, further comprising:

9. Forming a fourth lithography mask on the film laminate, wherein the fourth lithography mask has a plurality of openings for exposing the first plurality of contact openings and one or more second portions of the second plurality of contact openings, To further increase the etching depth of the first plurality of contact openings and the one or more second portions of the second plurality of contact openings, the film laminate is etched through the plurality of openings of the fourth lithography mask. The method according to claim 8, further comprising:

10. The method according to claim 9, wherein etching the film laminate through the plurality of openings of the fourth lithography mask further increases the etching depth of the first plurality of contact openings and the first portion of the second plurality of contact openings.

11. To increase the depth of the second subset of the first plurality of contact openings and the second subset of the second plurality of contact openings, the film laminate is etched and then gap fill is removed from one or more contact openings among the first plurality of contact openings and the second plurality of contact openings, After removing the gap fill, the first layer is removed in order to form a plurality of word line openings within the film laminate. By depositing the first conductive material within the plurality of word line openings, a plurality of word lines are formed. Removing the liner from the bottom of the first plurality of contact openings and the second plurality of contact openings, To form multiple word line contacts, conductive material is deposited in the first and second multiple contact openings. The method according to claim 6, further comprising:

12. Forming the patterned hard mask Directly depositing a hard mask onto the upper surface of the aforementioned film laminate, In order to expose the upper surface of the film laminate, a plurality of openings are formed through the hard mask. The method according to claim 6, including the method described in claim 6.

13. Forming the multiple openings through the hard mask is Forming a lithography mask on the aforementioned hard mask, In order to expose the upper surface of the hard mask, multiple hard mask openings are etched through the lithography mask, To selectively expose the upper surface of the film laminate, etching is performed through the plurality of hard mask openings. The method according to claim 12, including the method described in claim 12.

14. The method according to claim 6, wherein the hard mask is a tungsten hard mask.

15. Processor and A memory that stores instructions that can be executed by the aforementioned processor and The instruction is provided, The method involves forming a patterned hard mask and a first lithography mask on a film laminate, wherein the film laminate comprises a plurality of alternately arranged first and second layers, forming the patterned hard mask and the first lithography mask. To form a first set of contact openings within the film stack, the film stack is etched through the openings of the first lithography mask, Expanding the opening of the first lithography mask in the first direction, Etching the film laminate through the openings of the first lithography mask in order to form a second plurality of contact openings within the film laminate, wherein the depth of the first plurality of contact openings increases as the second plurality of contact openings are formed. To increase the depth of the first subset of contact openings and the second subset of contact openings, the film laminate is etched through the openings of a second lithography mask formed on the film laminate, Etching the film laminate through the openings of the second lithography mask in order to increase the depth of the second subset of the first plurality of contact openings and the second subset of the second plurality of contact openings, wherein the depth of the first plurality of contact openings and the second plurality of contact openings changes in the first and second directions. A system designed to perform [something].

16. The system according to claim 15, further comprising instructions executable by the processor for increasing the depth of the subset of the first plurality of contact openings and the depth of the subset of the second plurality of contact openings as the depth of the subset of the second plurality of contact openings increases.

17. Instructions that can be executed by the aforementioned processor, The third lithography mask is formed on the film laminate, wherein the third lithography mask has a plurality of openings for exposing a first plurality of contact openings and one or more first portions of a second plurality of contact openings. To further increase the etching depth of the first plurality of contact openings and the first plurality of contact openings, and the first or more first portions of the second plurality of contact openings, the film laminate is etched through the plurality of openings of the third lithography mask. The system according to claim 15, further comprising instructions for performing the following.

18. Instructions that can be executed by the aforementioned processor, Forming a fourth lithography mask on the film laminate, wherein the fourth lithography mask has a plurality of openings for exposing the first plurality of contact openings and one or more second portions of the second plurality of contact openings, To further increase the etching depth of the first plurality of contact openings and the one or more second portions of the second plurality of contact openings, the film laminate is etched through the plurality of openings of the fourth lithography mask. The system according to claim 15, further comprising instructions for performing the following.

19. The system according to claim 18, wherein etching the film laminate through the plurality of openings of the fourth lithography mask further increases the etching depth of the first plurality of contact openings and the one or more first portions of the second plurality of contact openings.

20. Instructions that can be executed by the aforementioned processor, The method involves forming multiple word lines by depositing a first conductive material within multiple word line openings, wherein the word line openings are formed after gap fill has been removed from one or more contact openings of the first and second multiple contact openings, and the method involves forming multiple word lines. Removing the liner from the bottom of the first plurality of contact openings and the second plurality of contact openings, In order to form multiple word line contacts, a second conductive material is deposited in the first and second multiple contact openings. The system according to claim 15, further comprising instructions for performing the following.

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