Word line contact formation for NAND devices

Abstract

A method of direct word line contact formation for a 3D NAND device is disclosed. A method may include providing a first film stack including a first plurality of alternating first and second layers, and forming a first plurality of contact holes in the first film stack, where each contact hole is formed to a different etch depth. The method may further include forming a sacrificial gap fill within the first plurality of contact holes and forming a second film stack atop the first film stack, where the second film stack includes a second plurality of alternating first and second layers. The method may further include forming a second plurality of contact holes in the second film stack, where a first set of contact holes in the second plurality of contact holes extend to the sacrificial gap fill, and removing the sacrificial gap fill from the first plurality of contact holes.

Description

[0001] Related applications

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 429,856, filed on December 2, 2022, entitled “Word Line Contact Formation for NAND Devices,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present embodiments relate to processing of NAND devices, and more particularly, to methods for direct wordline contact formation for 3D NAND devices. Background Art

[0004] According to current substrate (e.g., wafer) manufacturing methods, etch rates, etch profiles, and etch selectivity are optimized to reduce manufacturing costs and increase circuit element density on the substrate. However, etched features (such as memory holes) continue to shrink in size and / or increase in aspect ratio (e.g., the ratio of feature depth to width). For example, in three-dimensional (3D) NAND device manufacturing, substrates can include up to 96 layers and can be expanded to up to 128 layers. Furthermore, the aspect ratio of memory holes, for example, can range from 100 to 200, while the depth of the memory holes ranges from approximately 6 μm to 8 μm, making memory hole etching one of the most critical and challenging steps in 3D NAND device manufacturing. For example, this high-aspect ratio etch requires not only high etch rates and high etch selectivity (e.g., to mask materials on the substrate), but also straight profiles without bowing and twisting, no under-etching and minimal microloading, minimal aspect ratio-dependent etching (ARDE), and uniformity across the substrate (e.g., critical dimension (CD) variation 3σ < 1%).

[0005] When fabricating 3D NAND devices with a staircase arrangement of layers, wordline landing pads are initially defined through step formation (e.g., lithography and etching steps) and / or a dicing process in which multiple layers are etched down, followed by gapfill in the staircase area. However, since contact holes with different heights are formed in the same etch step, selectivity margin remains a challenge during wordline contact etching. Furthermore, using higher dry etch process temperatures to increase selectivity is constrained by hardware limitations.

[0006] It is with respect to these and other considerations that the present disclosure is provided. Summary of the Invention

[0007] In view of the above, a method may include providing a first film stack comprising a first plurality of alternating first and second layers, and forming a first plurality of contact holes in the first film stack, wherein each of the first plurality of contact holes is formed to a different etch depth relative to an upper surface of the first film stack. The method may further include forming a sacrificial gap fill within the first plurality of contact holes, and forming a second film stack atop the upper surface of the first film stack, wherein the second film stack comprises a second plurality of alternating first and second layers. The method may further include forming a second plurality of contact holes in the second film stack, wherein a first group of the second plurality of contact holes extends to the sacrificial gap fill, and removing the sacrificial gap fill from the first plurality of contact holes.

[0008] In some methods, a system may include a processor and a memory storing instructions executable by the processor for providing a first film stack comprising a first plurality of alternating first and second layers, and forming a first plurality of contact holes in the first film stack, wherein each of the first plurality of contact holes is formed to a different etch depth relative to an upper surface of the first film stack. The memory may further store instructions executable by the processor for forming a sacrificial gap fill within the first plurality of contact holes, and forming a second film stack atop the upper surface of the first film stack, wherein the second film stack comprises a second plurality of alternating first and second layers. The memory may further store instructions executable by the processor for forming a second plurality of contact holes in the second film stack, wherein a first group of the second plurality of contact holes extends to the sacrificial gap fill, and removing the sacrificial gap fill from the first plurality of contact holes.

[0009] In some methods, a memory device may include a layer stack comprising a first film stack and a second film stack, wherein the layer stack includes a plurality of alternating first layers and horizontally oriented word lines, and a first plurality of contact holes and a second plurality of contact holes formed vertically through the first film stack and the second film stack, wherein each of the first and second plurality of contact holes extends to an upper surface of the layer stack, and wherein each of the plurality of contact holes is formed to a different etch depth relative to the upper surface of the layer stack. The memory device may further include a word line contact formed within each of the plurality of contact holes. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The accompanying drawings illustrate exemplary methods of the present disclosure, including practical applications of its principles, as follows:

[0011] Figure 1 A side cross-sectional view of a patterned first masking layer over a stack of alternating first and second layers of an exemplary device is shown according to an embodiment of the present disclosure;

[0012] Figure 2 A side cross-sectional view of a first set of contact holes formed in a stack of alternating first and second layers of an exemplary device is shown according to an embodiment of the present disclosure;

[0013] Figure 3 A side cross-sectional view of a patterned second masking layer over a stack of alternating first and second layers of an exemplary device is shown according to an embodiment of the present disclosure;

[0014] Figure 4 A side cross-sectional view of a second set of contact holes formed in a stack of alternating first and second layers of an exemplary device is shown according to an embodiment of the present disclosure;

[0015] Figure 5 A side cross-sectional view of a patterned third masking layer over a stack of alternating first and second layers of an exemplary device is shown according to an embodiment of the present disclosure;

[0016] Figure 6 A side cross-sectional view of a third set of contact holes formed in a stack of alternating first and second layers of an exemplary device is shown according to an embodiment of the present disclosure;

[0017] Figure 7 A side cross-sectional view of an exemplary device after forming a sacrificial gap fill within the contact hole and forming a second stack of alternating first and second layers is shown in accordance with an embodiment of the present disclosure;

[0018] Figure 8 A side cross-sectional view of an exemplary device after forming a plurality of contact holes through a second stack of alternating first and second layers is shown in accordance with an embodiment of the present disclosure;

[0019] Figure 9 A side cross-sectional view of an exemplary device after removal of a sacrificial gap fill is shown according to an embodiment of the present disclosure;

[0020] Figure 10 An embodiment according to the present disclosure shows a liner formed within a plurality of contact holes;

[0021] Figure 11 A side cross-sectional view of an exemplary device after removal of the second layer is shown according to an embodiment of the present disclosure;

[0022] Figure 12 A side cross-sectional view of an exemplary device after forming a plurality of word lines is shown according to an embodiment of the present disclosure;

[0023] Figure 13 A side cross-sectional view of an exemplary device after removing a liner from a bottom of each of a plurality of contact holes is shown according to an embodiment of the present disclosure;

[0024] Figure 14 A side cross-sectional view of an exemplary device after forming a plurality of word line contacts is shown according to an embodiment of the present disclosure;

[0025] Figure 15A An embodiment according to the present disclosure illustrates a top view of a NAND device including multiple contact layers formed therein;

[0026] Figure 15B According to the embodiment of the present disclosure, Figure 15A A side cross-sectional view of the NAND device along the sectional line BB';

[0027] Figure 15C According to the embodiment of the present disclosure, Figure 15A A side cross-sectional view of the NAND device along the cut line CC';

[0028] Figure 15D According to the embodiment of the present disclosure, Figure 15A A side cross-sectional view of the NAND device along the tangent line D-D';

[0029] Figure 15E According to the embodiment of the present disclosure, Figure 15A A side cross-sectional view of contacts of a NAND device;

[0030] Figure 16A A cross-sectional side perspective view of a NAND device along the tangent line EE' is shown according to an embodiment of the present disclosure;

[0031] Figure 16B A cross-sectional side view of contacts of a NAND device is shown according to an embodiment of the present disclosure;

[0032] 17A to 17D A side perspective view of an exemplary device during formation of a plurality of contact holes is shown according to an embodiment of the present disclosure;

[0033] Figure 18 is a schematic diagram of an exemplary system according to an embodiment of the present disclosure; and

[0034] Figure 19 A process flow for a method of forming an exemplary device is depicted according to an embodiment of the present disclosure.

[0035] The accompanying drawings are not necessarily drawn to scale. The accompanying drawings are merely representations and are not intended to represent specific parameters of the present disclosure. The accompanying drawings are intended to depict exemplary embodiments of the present disclosure and are not therefore to be considered limiting of the scope. In the accompanying drawings, the same reference numerals represent the same elements.

[0036] Furthermore, for clarity of illustration, some elements may be omitted or not shown to scale in some of the drawings. For clarity of illustration, cross-sectional views may be presented as "sliced" or "close-up" cross-sectional views, omitting certain background lines that would otherwise be visible in "true" cross-sectional views. Furthermore, for clarity, some reference numerals may be omitted in some of the drawings. DETAILED DESCRIPTION

[0037] The methods, systems, and apparatus according to the present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which various embodiments are shown. The methods, systems, and apparatus may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and fully convey the scope of the methods to those skilled in the art.

[0038] Embodiments described herein are directed to a 3D NAND wordline contact-first approach with increased feasibility for integration with other high aspect ratio modules (e.g., slit and CMOS contacts). The direct wordline contact technology of the present disclosure can reduce multiple conventional processing steps (e.g., step formation lithography and etching, cutting lithography and etching, step area gapfill deposition, and planarization), and thus provide significant throughput and cost benefits. In addition, by forming the wordline contact holes prior to wordline metal deposition, contact metal selectivity is improved, and the use of termination layers and wordline landing pads can be eliminated. Still further, the methods of the present disclosure allow for larger CDs at lower layers of the device, which can increase contact landing margins and reduce the burden of lithographic alignment errors.

[0039] Figure 1 A side cross-sectional view of a memory device (hereinafter referred to as "device") 100 at an early stage of processing is shown, according to one or more embodiments described herein. Device 100 may include a first film stack 102 having a plurality of alternating horizontal first layers 106A-106E and second layers 108A-108D stacked atop one another. First film stack 102 may be part of a memory cell device, such as a three-dimensional (3D) memory device (e.g., NAND). Although not limiting, first layers 106A-106E may be a dielectric material such as silicon oxide (SiO), and second layers 108A-108D may be a second dielectric material such as silicon nitride. In other embodiments, suitable dielectric materials for first layers 106A-106E and / or second layers 108A-108D may include silicon oxynitride, silicon carbide, silicon oxycarbide, titanium nitride, a composite of an oxide and a nitride, at least one or more oxide layers sandwiched between nitride layers, combinations thereof, and the like.

[0040] As further shown, the device 100 can include a first masking layer 110 formed directly atop the upper surface 112 of the first film stack 102. The first masking layer 110 can be a photoresist layer including a set (i.e., one or more) of first masking holes 115A, 115B formed (e.g., etched) therein. As shown, the first masking holes 115A, 115B can be selectively formed relative to the upper surface 112 of the first film stack 102.

[0041] Figure 2 A set of first contact holes or apertures 118A, 118B are shown formed through the top layer of the first film stack 102. In the embodiment shown, the first contact holes 118A, 118B are formed through the uppermost first layer 106A, which is exposed within first masking holes 115A, 115B of the first masking layer 110. The first contact holes 118A, 118B can be selectively etched relative to the upper surface 123 of the second layer 108A.

[0042] like Figure 3 As shown, a second masking layer 124 can then be formed over the first film stack 102 and etched to form a set of second masking holes 126A, 126B therein. As shown, the second masking layer 124 can cover the first contact hole 118A, while the second masking holes 126B can be aligned with the first contact hole 118B. The masking holes 126A can be formed between the first contact holes 118A, 118B.

[0043] like Figure 4 As shown, the first film stack 102 may be etched again to form a set of third contact holes 128A, 128B. Etching may be performed on the device 100 while the second masking layer 124 is present, followed by removal of the second masking layer. Therefore, the first contact hole 118A is generally unaffected by this etching step. Third contact holes 128A are formed through the first layer 106A, the second layer 108A, and the first layer 106B. Third contact holes 128A may extend to and expose an upper surface 130 of the second layer 108B. Simultaneously, third contact holes 128B are formed through the first layer 106A, the second layer 108A, the first layer 106B, the second layer 108B, and the first layer 106C. Third contact holes 128B may extend to and expose an upper surface 131 of the second layer 108C. As shown, the first contact hole 118A and the third contact holes 128A and 128B extend to different depths relative to the upper surface 112 of the first film stack 102.

[0044] like Figure 5As shown, a third masking layer 132 can then be formed over the first film stack 102 and etched to form a third masking hole 134 therein. As shown, the third masking layer 132 can cover the first contact hole 118A and the third contact holes 128A, 128B. The third masking hole 134 can be selectively formed relative to the upper surface 112 of the first film stack 102.

[0045] like Figure 6 As shown, the first film stack 102 can be etched again to form a fourth contact hole 136. Etching can be performed on the device 100 while the third masking layer 132 is present, followed by removal of the third masking layer. Thus, during the formation of the fourth contact hole 136, the first contact hole 118A and the third contact holes 128A, 128B are generally unaffected. The fourth contact hole 136 is formed through the first layers 106A, 106D and through the second layers 108A-108C. The fourth contact hole 136 can extend to and expose an upper surface 139 of the second layer 108D. As shown, the first contact hole 118A, the third contact hole 128A, the third contact hole 128B, and the fourth contact hole 136 extend to different depths relative to the upper surface 112 of the first film stack 102. Depending on the number of layers present in the first film stack 102, the masking and etching steps may be repeated. It will be appreciated that the device 100 may include a greater number of layers in other examples.

[0046] like Figure 7 As shown, sacrificial gap fill 127 can be formed within first contact hole 118A, third contact hole 128A, third contact hole 128B, and fourth contact hole 136 of first film stack 102. In some embodiments, sacrificial gap fill 127 can be deposited over first film stack 102 and then selectively planarized relative to upper surface 112. Second film stack 103 can then be formed atop first film stack 102, including over sacrificial gap fill 127. As shown, second film stack 103 can include a second plurality of alternating first layers 113A-113D and horizontally arranged second layers 111A-111D. Although not limiting, first layers 113A-113D can be a dielectric material, such as silicon oxide (SiO), and second layers 111A-111D can be a second dielectric material, such as silicon nitride. In other embodiments, suitable dielectric materials for the first layers 113A-113D and / or the second layers 111A-111D may include silicon oxynitride, silicon carbide, silicon carbon oxide, titanium nitride, a composite of oxide and nitride, at least one or more oxide layers sandwiched between nitride layers, and combinations of the above, among others.

[0047] like Figure 8As shown, a first set of contact holes 125A-125D and a second set of contact holes 129A-129D can be formed in the second film stack 103. Although not shown, multiple masking and lithography steps can be used to form the first set of contact holes 125A-125D and the second set of contact holes 129A-129D. As shown, the first set of contact holes 125A-125D can be aligned with and extend to the upper surface 133 of the sacrificial gap fill 127. The second set of contact holes 129A-129D can each extend to a different depth relative to the upper surface 135 of the second film stack 103. For example, contact hole 129A can extend to the second layer 111A, contact hole 129B can extend to the second layer 111B, contact hole 129C can extend to the second layer 111C, and contact hole 129D can extend to the second layer 111D.

[0048] Then, if Figure 9 As shown, the sacrificial gap fill 127 can be removed and a liner 140 can then be formed over the device 100, including within each of the first set of contact holes 125A-125D and the second set of contact holes 129A-129D (hereinafter also collectively referred to as the second plurality of contact holes), as shown. Figure 10 As shown. A liner 140 may also be formed within each of the first contact hole 118A, the third contact hole 128A, the third contact hole 128B, and the fourth contact hole 136 (hereinafter collectively referred to as the first plurality of contact holes) of the first film stack 102. In some embodiments, the liner 140 may be an oxide layer (e.g., SiO, AlO, etc.) formed along the upper surface 135 of the second film stack 103 and along the sidewalls 148 and bottoms 149 of the first and second pluralities of contact holes (e.g., via atomic layer deposition (ALD)). As further shown, a gap fill 141 may be formed within each of the first and second pluralities of contact holes.

[0049] like Figure 11 As shown, the second layers 108A-108D of the first film stack 102 and the second layers 111A-111D of the second film stack 103 have been removed, e.g., by a horizontal wet etching process, to form a plurality of wordline holes 150 in the device 100. The first layers 106A-106E of the first film stack 102 and the first layers 113A-113D of the second film stack are generally unaffected by the wet etching, as is the liner 140, which remains within the first and second pluralities of contact holes.

[0050] A plurality of word lines 152 may then be formed in the device 100, such as Figure 12 As shown, by depositing a first conductive material 154 (eg, titanium tungsten (W) or molybdenum (Mo)) within the plurality of wordline holes 150. The gap fill 141 and liner 140 may then be removed, as shown. Figure 131 and 2. As shown, the liner 140 is removed from the bottom 149 of the first and second pluralities of contact holes. In some embodiments, the liner 140 can be vertically etched to expose the upper surface 156 of one or more of the plurality of word lines 152. As shown, the liner 140 remains along the sidewalls 148 of the first and second pluralities of contact holes. In some embodiments, the liner 140 is also removed from the upper surface 135 of the second film stack 103.

[0051] like Figure 14 As shown, a second conductive material 160 can be deposited within the first and second pluralities of contact holes to form a plurality of wordline contacts 162. In some embodiments, the second conductive material 160 can be tungsten, deposited atop the upper surface 156 of the plurality of wordlines 152 along with titanium nitride (TiN), for example, via atomic layer deposition. The second conductive material 160 can be separated from the first layers 106A-106E and the first layers 113A-113D by a liner 140 that runs along the sidewalls 148 of the first and second pluralities of contact holes. In some embodiments, voids 157 may exist within the conductive material 160 in the first contact hole 118A, the third contact hole 128A, the third contact hole 128B, and the fourth contact hole 136 of the first film stack 102 due to the aspect ratios of these contact holes.

[0052] Figure 15A is a top view of a device 200 including multiple layers of wordline contacts formed in a plurality of film stacks 202. For example, a top layer may include a first plurality of wordline contacts 205, a middle layer may include a second plurality of wordline contacts 209, and a bottom layer may include a third plurality of wordline contacts 213. Although not shown, it will be appreciated that additional layers are possible in alternative embodiments. Each of the first, second, and third pluralities of wordline contacts 205, 209, and 213 may be formed using Figures 1 to 14 1 and formed by the methods described above. For example, the top layer may correspond to the wordline contacts 162 formed in the second set of contact holes 129A-129D of the second film stack 103, while the middle and / or bottom layers may correspond to the wordline contacts 162 formed in the first contact hole 118A, the third contact hole 128A, the third contact hole 128B, and the fourth contact hole 136 of the first film stack 102. The first slit 267 and the second slit 269 may be formed on opposite sides of the device 200.

[0053] Figures 15B to 15D Shown Figure 15ASide cross-sectional views of the device 200 along tangents B-B', C-C', and D-D' respectively. As shown, the depth of the first column 272 of the first plurality of word line contacts 205 in the top layer increases between the first slit 267 and the second slit 269. Similarly, the depth of the second column 273 and the third column 274 of the first plurality of word line contacts 205 in the top layer increases between the first slit 267 and the second slit 269. As further shown, the average depth of the first column 272, the second column 273, and the third column 274 of the first plurality of word line contacts 205 increases towards the middle layer. However, each of the first plurality of contacts 205 may extend completely to the upper surface 235 of the device 200, eliminating the need for a stepped arrangement of the device 200.

[0054] Figure 15E The word line contact 205A of the third column 274 of the first plurality of word line contacts 205 is shown in more detail. The word line contact 205A may be formed through the plurality of word lines 252 of the film stack 202, where the liner 240 may be formed within the contact hole 207. The contact liner 266 and the conductive material 260 may be deposited within the contact hole 207 to form the word line contact 205A. In various embodiments, the conductive material 260 may be W, tungsten silicide (WSi), tungsten polysilicon (W / poly), tungsten alloy, tantalum (Ta), titanium (Ti), copper (Cu), ruthenium (Ru), nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), manganese (Mn), aluminum (Al), hafnium (Hf), vanadium (V), molybdenum (Mo), palladium (Pd), gold (Au), silver (Au), platinum (Pt), alloys of the above items, or combinations of the above items. Meanwhile, the contact liner 266 may be a metal nitride layer or a metal silicon nitride layer, such as TiN, tantalum nitride (TaN), TaSiN, TiSiN, and combinations of the above items, etc.

[0055] Figure 16A Shows Figure 15A Side cross-sectional view of the device 200 along tangent E-E'. As shown, the depth of each word line contact 213A of the column 279 of the third plurality of word line contacts 213 increases between the first slit 267 and the second slit 269. However, each word line contact 213A of the column 279 extends to the upper surface 235 of the film stack 202.

[0056] As Figure 16B Better shown in, each word line contact 213A may include a liner 240 and a contact liner 266 formed within the contact hole. As shown, the contact word line contact 213A may have a first width 'W1', a second width 'W2', and a third width 'W3', where W1 < W2 < W3. Due to the hierarchical width configuration of the word line contact 213A, voids 257 may exist within the lower portion 281 of the conductive material 260.

[0057] Figures 17A to 17D Further shown is a plurality of wordline contact holes 301 formed in a film stack 302 according to the methods described herein. The plurality of contact holes 301 can be formed using the same or similar methods as used to form the wordline contact holes of devices 100 and / or 200 (e.g., etching 305). In the embodiment shown, a total of 360 ON pairs can be formed in device 300, with 120 pairs present in each layer. For example, as shown in Table 1 below, seven (7) etching / lithography steps are used to form 360 pairs in three layers.

[0058]

[0059] Figure 18 A schematic diagram of an example system / apparatus 400 is shown according to an embodiment of the present disclosure. The operation of the system 400 will be described with reference to the apparatus 100. In some embodiments, the system 400 can be a cluster tool operable to perform the processes required to form the apparatus 100 and the apparatus 200 described herein. Although not limiting, the system 400 can include at least one central transfer station / chamber 402 and one or more robots 404 within the transfer station / chamber 402, wherein the robots 404 are operable to move robot blades and wafers to and from each of a plurality of processing chambers 410A-410N connected to or positioned adjacent to the transfer station / chamber 402. In some embodiments, the system 400 can include any of a variety of suitable chambers, including but not limited to a first deposition chamber 410A, a first etch chamber 410B, a second deposition chamber 410C, a second etch chamber 410D, and a third deposition chamber 410E. The first deposition chamber 410A, the second deposition chamber 410C, and the third deposition chamber 410E 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. The specific arrangement of the processing chambers and components may vary depending on the cluster tool and should not be considered to limit the scope of the present disclosure. For example, in an alternative embodiment, there is only a single deposition chamber and / or only a single etching chamber in the system 400. In another example, one or more deposition chambers may include multiple processing areas within the same chamber, which allows for a common gas supply, common pressure control, and common process gas exhaust / extraction. The modular design of the system enables rapid conversion from one configuration to any other configuration.

[0060] In some embodiments, first deposition chamber 410A can be used to deposit first film stack 102 as alternating first layers 106A-106E and second layers 108A-108D, and to deposit second film stack 103 as alternating first layers 113A-113D and second layers 111A-111D. First deposition chamber 410A can further be used to deposit a plurality of masking layers (e.g., first masking layer 110, second masking layer 124, and third masking layer 132) over first film stack 102.

[0061] The first etching chamber 410B can be used to etch multiple masking layers and form multiple contact holes (e.g., the first contact hole 118A, the third contact hole 128A, the third contact hole 128B, and the fourth contact hole 136). The first etching chamber 410B can be further used to form a first plurality of contact holes in the first film stack 102 and a second plurality of contact holes in the second film stack 103. The first etching chamber 410B can be further used to perforate the liner 140 along the bottom 149 of each of the first and second plurality of contact holes.

[0062] The second deposition chamber 410C may be used to deposit the liner 140 over the device 100 , including depositing the liner within each of the first and second pluralities of contact holes, and depositing the sacrificial gapfill 127 within the first plurality of contact holes.

[0063] The second etch chamber 410D may be used to remove the first layers 106A-106E and the first layers 113A-113D to form a plurality of wordline holes 150 in the first and second film stacks 102, 103. In some embodiments, a wet etching process may be performed in the second etch chamber 410D.

[0064] The third deposition chamber 410E can be used to form a plurality of word lines 152 by depositing a first conductive material 154 within the plurality of word line holes 150. The third deposition chamber 410E (or another deposition chamber) can further be used to deposit a second conductive material 160 within the first and second pluralities of contact holes to form a plurality of word line contacts 162 within the device 100.

[0065] The system controller 420 communicates with the robot 404, the transfer station / chamber 402, and the plurality of processing chambers 410A-410E. The system controller 420 may be any suitable component that can control the processing chambers 410A-410E and the robot 404, as well as the processes occurring within the processing chambers 410A-410E. For example, the system controller 420 may be a computer including a central processing unit 422, a memory 424, suitable circuitry / logic / instructions, and memory.

[0066] Programs or instructions may generally be stored as software routines in the memory 424 of the system controller 420 that, when executed by the processor 422, cause the processing chambers 410A-410N to perform the processes of the present disclosure. The software routines may also be stored and / or executed by a second processor (not shown) that is remotely located from the hardware controlled by the processor 422. Some or all of the methods of the present disclosure may also be implemented in hardware. Thus, the processes may 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 the processor 422, the software routines transform a general-purpose computer into a special-purpose computer (controller) that controls chamber operation to perform the processes.

[0067] Now go to Figure 19 , shows a process 500 according to an embodiment of the present disclosure. At block 501, process 500 may include providing a first film stack including a plurality of alternating first and second layers. In some embodiments, a first layer in the plurality of alternating first and second layers is a dielectric material, and a second layer in the plurality of alternating first and second layers is a dielectric material or a conductive material. In some embodiments, a first layer in the plurality of alternating first and second layers is silicon oxide, and a second layer in the plurality of alternating first and second layers is silicon nitride.

[0068] In box 502, process 500 may include forming a plurality of contact holes in a first film stack, wherein each contact hole in the plurality of contact holes is formed to a different etch depth relative to an upper surface of the film stack. In some embodiments, forming the plurality of contact holes in the film stack may include patterning a first group of holes through a first masking layer, and etching a first group of contact holes in the plurality of contact holes through the first group of holes. Forming the plurality of contact holes in the film stack may further include patterning a second group of holes through a second masking layer, wherein one hole in the second group of holes is aligned with one of the first group of contact holes, and etching a second group of contact holes in the plurality of contact holes through the second group of holes. Forming the plurality of contact holes in the film stack may further include patterning a third group of holes through a third masking layer, wherein the third masking layer is formed above the first and second groups of contact holes, and etching a third group of contact holes in the plurality of contact holes through the third group of holes. In some embodiments, a first depth of the first group of contact holes is less than a second depth of the second group of contact holes, and the second depth is less than a third depth of the third group of contact holes.

[0069] At block 503, the process 500 may include forming a sacrificial gapfill within the first plurality of contact holes. In some embodiments, the sacrificial gapfill may be deposited and then planarized.

[0070] At block 504 , the process 500 may include forming a second film stack atop the upper surface of the first film stack, wherein the second film stack includes a second plurality of alternating first and second layers.

[0071] At block 505 , the process 500 may further include forming a second plurality of contact holes in the second film stack, wherein a first set of contact holes in the second plurality of contact holes extends to a sacrificial gapfill.

[0072] At block 506, the process 500 may further include removing the sacrificial gap fill from the first plurality of contact holes. In some embodiments, the sacrificial gap fill may be etched.

[0073] At block 507 , the process 500 may include depositing a liner over the second film stack, including depositing a liner within each of the first and second pluralities of contact holes.

[0074] At block 508, the process 500 may include removing the first layer to form a plurality of wordline holes in the first and second film stacks. In some embodiments, the wordline holes are formed using a lateral wet etching process.

[0075] At block 509 , the process 500 may include forming a plurality of word lines by depositing a first conductive material in the plurality of word line holes. In some embodiments, the first conductive material is W or Mo.

[0076] At block 510, process 500 may include removing a liner from a bottom of each of the plurality of contact holes. In some embodiments, the liner is removed from the bottom of each of the first and second pluralities of contact holes, exposing an upper surface of one or more of the plurality of word lines. In some embodiments, the liner is removed from the bottom of each of the first and second pluralities of contact holes without removing the liner from a sidewall of each of the first and second pluralities of contact holes.

[0077] At block 511, process 500 may include depositing a second conductive material within the first and second plurality of contact holes to form a plurality of wordline contacts. In some embodiments, the second conductive material may be W, which is deposited atop upper surfaces of the plurality of wordlines along with TiN.

[0078] In various embodiments, a design tool can be provided and configured to create a data set for patterning, for example, a semiconductor layer of a device as described herein. For example, a data set can be created to generate a mask for patterning a layer of a structure as described herein in a lithography operation. Such a design tool can include a collection of one or more modules and can also include hardware, software, or a combination of the above. Thus, for example, a tool can be a collection of one or more software modules, hardware modules, software / hardware modules, or any combination or permutation of the above. As another example, a tool can be a computing device or other application running software or implemented in hardware.

[0079] For convenience and clarity, terms such as "top," "bottom," "upper," "lower," "vertical," "horizontal," "lateral," and "longitudinal" will be used herein to describe the relative position and orientation of components and their parts as they appear in the drawings. The terminology will include the words specifically mentioned, their derivatives, and words of similar import.

[0080] As used herein, an element or operation recited in the singular and beginning with the word "a" or "an" should be understood to include plural elements or operations until such exclusion is explicitly stated. Furthermore, reference to "one embodiment" of the present disclosure is not intended to be limiting. Additional embodiments may also incorporate recited features.

[0081] Furthermore, in some embodiments, the terms "substantially" or "essentially" and the terms "approximately" or "approximately" can be used interchangeably and can be described using any relative measure acceptable to one of ordinary skill in the art. For example, these terms can be used as a comparison to a reference parameter to indicate a deviation from the ability to provide the intended function. Although not limiting, the deviation from the reference parameter can be, for example, less than 1%, less than 3%, less than 5%, less than 10%, less than 15%, less than 20%, etc.

[0082] Still further, those skilled in the art will understand that when an element, such as a layer, region, or substrate, is referred to as being formed, deposited, or disposed “on,” “over,” or “atop” another element, the element can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on,” “directly over,” or “directly atop” another element, there are no intervening elements present.

[0083] The scope of the present disclosure is not limited to the specific embodiments described herein. In fact, in addition to those described herein, various other embodiments and modifications of the present disclosure will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. Therefore, such other embodiments and modifications are intended to fall within the scope of the present disclosure. In addition, the present disclosure has been described herein in the context of specific implementations in specific environments for specific purposes. Those of ordinary skill in the art will recognize that usefulness is not limited thereto, and the present disclosure may be beneficially implemented in any number of environments for any number of purposes. Therefore, the claims set forth below will be interpreted in light of the full breadth and spirit of the present disclosure as described herein.

Claims

1. A method comprising: providing a first film stack comprising a first plurality of alternating first and second layers; forming a first plurality of contact holes in the first film stack, wherein each contact hole in the first plurality of contact holes is formed to a different etch depth relative to an upper surface of the first film stack; forming a sacrificial gap fill within the first plurality of contact holes; forming a second film stack atop the upper surface of the first film stack, wherein the second film stack comprises a second plurality of alternating first and second layers; forming a second plurality of contact holes in the second film stack, wherein a first set of contact holes in the second plurality of contact holes extends to the sacrificial gapfill; and The sacrificial gap fill is removed from the first plurality of contact holes.

2. The method of claim 1, further comprising: depositing a liner over the second film stack, including depositing the liner within each of the first and second pluralities of contact holes; removing the first layer to form a plurality of wordline holes in the first and second film stacks; forming a plurality of word lines by depositing a first conductive material within the plurality of word line holes; removing the liner from bottoms of the first and second pluralities of contact holes; and A second conductive material is deposited within the first and second pluralities of contact holes to form a plurality of wordline contacts.

3. The method of claim 2, wherein the liner is removed from the bottom of the first and second pluralities of contact holes but is not removed from the sidewalls of each of the first and second pluralities of contact holes.

4. The method of claim 2 , wherein forming the second plurality of contact holes comprises: etching the first set of contact holes through the second film stack to expose an upper surface of the sacrificial gapfill; and A second set of contact holes is formed adjacent to the first set of contact holes, wherein each contact hole in the second set of contact holes is formed to a different etch depth relative to the upper surface of the second film stack.

5. The method of claim 1 , wherein depositing the second conductive material within the first and second pluralities of contact holes to form the plurality of word line contacts comprises depositing tungsten within the first and second pluralities of contact holes, and wherein each of the plurality of word line contacts extends to the upper surface of the second film stack.

6. The method of claim 1 , wherein forming the plurality of contact holes in the first film stack comprises: patterning a first set of holes through the first masking layer; etching a first set of contact holes in the first plurality of contact holes through the first set of holes; patterning a second set of holes through the second masking layer, wherein a hole in the second set of holes is aligned with a contact hole in the first set of contact holes; etching a second set of contact holes in the first plurality of contact holes through the second set of holes; patterning a third set of holes through a third masking layer, wherein the third masking layer is formed over the first and second sets of contact holes; and A third set of contact holes in the first plurality of contact holes is etched through the third set of holes.

7. The method of claim 6, wherein the first depth of the first group of contact holes is less than the second depth of the second group of contact holes, and wherein the second depth of the second group of contact holes is less than the third depth of the third group of contact holes.

8. The method of claim 1, wherein the first layer of the first and second pluralities of alternating first and second layers is silicon dioxide, and wherein the second layer of the first and second pluralities of alternating first and second layers is silicon nitride.

9. The method of claim 1 , wherein each of the first plurality of contact holes in the first film stack has a first diameter, wherein each of the second plurality of contact holes in the second film stack has a second diameter, and wherein the first diameter is greater than the second diameter.

10. A system comprising: processor; a memory storing instructions executable by the processor, configured to: providing a first film stack comprising a first plurality of alternating first and second layers; forming a first plurality of contact holes in the first film stack, wherein each contact hole in the first plurality of contact holes is formed to a different etch depth relative to an upper surface of the first film stack; forming a sacrificial gap fill within the first plurality of contact holes; forming a second film stack atop the upper surface of the first film stack, wherein the second film stack comprises a second plurality of alternating first and second layers; forming a second plurality of contact holes in the second film stack, wherein a first set of contact holes in the second plurality of contact holes extends to the sacrificial gapfill; and The sacrificial gap fill is removed from the first plurality of contact holes.

11. The system of claim 10, further comprising instructions executable by the processor for: depositing a liner over the second film stack, including depositing the liner within each of the first and second pluralities of contact holes; removing the first layer to form a plurality of wordline holes in the first and second film stacks; forming a plurality of word lines by depositing a first conductive material within the plurality of word line holes; removing the liner from bottoms of the first and second pluralities of contact holes; and A second conductive material is deposited within the first and second pluralities of contact holes to form a plurality of wordline contacts.

12. The system of claim 11, wherein the liner is removed from the bottom of the first and second pluralities of contact holes without removing the liner from a sidewall of each of the first and second pluralities of contact holes.

13. The system of claim 10, the instructions executable by the processor to form the plurality of contact holes in the first film stack, further comprising instructions for: patterning a first set of holes through the first masking layer; etching a first group of contact holes in the first plurality of contact holes through the first group of holes; patterning a second set of holes through the second masking layer, wherein a hole in the second set of holes is aligned with a contact hole in the first set of contact holes; etching a second set of contact holes in the first plurality of contact holes through the second set of holes; patterning a third set of holes through a third masking layer, wherein the third masking layer is formed over the first and second sets of contact holes; and A third set of contact holes in the first plurality of contact holes is etched through the third set of holes.

14. The system of claim 13, wherein the first depth of the first group of contact holes is less than the second depth of the second group of contact holes, and wherein the second depth of the second group of contact holes is less than the third depth of the third group of contact holes.

15. The system of claim 10, wherein each of the first plurality of contact holes in the first film stack has a first diameter, wherein each of the second plurality of contact holes in the second film stack has a second diameter, and wherein the first diameter is greater than the second diameter.

16. The system of claim 10, wherein the instructions are executable by the processor to form the second plurality of contact holes, further comprising instructions for: etching the first set of contact holes through the second film stack to expose an upper surface of the sacrificial gapfill; and A second set of contact holes is formed adjacent to the first set of contact holes, wherein each contact hole in the second set of contact holes is formed to a different etch depth relative to the upper surface of the second film stack.

17. A memory device, comprising: a layer stack comprising a first film stack and a second film stack, wherein the layer stack comprises a plurality of alternating first layers and horizontally-oriented word lines; a first plurality of contact holes and a second plurality of contact holes formed vertically through the first film stack and the second film stack, wherein each contact hole of the first and second pluralities of contact holes extends to an upper surface of the layer stack, and wherein each contact hole of the first and second pluralities of contact holes is formed to a different etch depth relative to the upper surface of the layer stack; and A wordline contact is formed in each of the first and second pluralities of contact holes. 18 . The memory device of claim 17 , further comprising a liner formed along a sidewall of each of the plurality of contact holes.

19. The memory device of claim 17, wherein each contact hole in the first plurality of holes has a first diameter, wherein each contact hole in the second plurality of holes has a second diameter, and wherein the first diameter is greater than the second diameter.

20. The memory device of claim 17, wherein the first layer of the layer stack is a dielectric material, wherein the word line is a first conductive material, wherein the word line contact is a second conductive material, and wherein the first and second conductive materials are in direct contact with each other.

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