High-Conformal Metal Etching in High-Aspect-Ratio Semiconductor Features

Abstract

An exemplary semiconductor processing method may include supplying an oxygen-containing precursor to a semiconductor processing chamber in which a substrate can be positioned. The substrate may include a trench formed between two columns and a molybdenum-containing metal region within a plurality of recesses formed in at least one of the columns. At least two of the molybdenum-containing metal regions may be connected by a molybdenum-containing first liner formed on at least a part of the sidewall of the trench. The method may include forming a plasma of the oxygen-containing precursor. The method may include contacting the molybdenum-containing first liner with the plasma effluent of the oxygen-containing precursor, thereby forming an oxidized portion of molybdenum. The method may include supplying a halogenated precursor. The method may include contacting the oxidized portion of molybdenum with the plasma effluent of the halogenated precursor, thereby removing the oxidized portion of molybdenum from the sidewall of the trench.

Description

Technical Field

[0001] Cross - Reference to Related Applications

[0001] This application claims the benefit of U.S. Patent Application No. 17 / 827,356, filed May 27, 2022, the entire disclosure of which is hereby incorporated by reference herein.

[0002]

[0002] This technology relates to semiconductor processes and equipment. More specifically, this technology relates to the lateral etching of molybdenum in a vertical structure.

Background Art

[0003]

[0003] Integrated circuits are made possible by a process of forming complexly patterned material layers on a substrate surface. To form a patterned material on a substrate, a controlled method for removing the exposed material is required. Chemical etching is used for various purposes, including transferring a pattern in a photoresist to a lower layer, thinning a layer, or reducing the lateral dimension of features already present on the surface. Often, an etching process that etches one material faster than another is desired to facilitate, for example, a pattern transfer process. Such an etching process is said to be selective to the first material. As materials, circuits, and processes have diversified, etching processes with selectivity to various materials have been developed.

[0004]

[0004] Etching processes can be referred to as wet or dry based on the materials used in the process. Wet HF etching preferentially removes silicon oxide over other dielectrics and materials. However, wet processes can sometimes be difficult to penetrate some restricted trenches and can also deform the remaining material at times. Dry etching generated by a local plasma formed within a substrate processing region can penetrate more restricted trenches and cause less deformation of fragile remaining structures. However, local plasma can damage the substrate because it generates an electrical arc during discharge.

[0005]

[0005] Accordingly, there is a need for improved systems and methods that can be used to manufacture high-quality devices and structures. These and other needs are addressed by the present technology.

Summary of the Invention

[0006]

[0006] An exemplary semiconductor processing method may include supplying an oxygen-containing precursor to a semiconductor processing chamber. A substrate may be positioned within the semiconductor processing chamber. The substrate may include trenches formed between columns and molybdenum-containing metal regions within a plurality of recesses formed in at least one of the columns. At least two of the molybdenum-containing metal regions may be connected by a molybdenum-containing first liner formed on at least a portion of a sidewall of the trench. The method may include forming a plasma of the oxygen-containing precursor in the semiconductor processing chamber. The method may include contacting the molybdenum-containing first liner with the plasma effluent of the oxygen-containing precursor. By the contact, an oxidized portion of molybdenum may be formed on the molybdenum-containing first liner. The method may include supplying a halogenated precursor to the semiconductor processing chamber. The method may include contacting the oxidized portion of molybdenum with the plasma effluent of the halogenated precursor. By the contact, the oxidized portion of molybdenum may be removed from the sidewall of the trench.

[0007]

[0007] In some embodiments, the oxygen-containing precursor may be ozone or may include ozone. The plasma of the oxygen-containing precursor may be formed with a plasma output of about 2000 W or less. The oxidized portion of molybdenum may be characterized by a thickness of about 100 Å or less. The halogenated precursor may be a fluorine-containing precursor or may include a fluorine-containing precursor. The fluorine-containing precursor may be tungsten hexafluoride or may include tungsten hexafluoride. By forming the oxidized portion of molybdenum, a layer of molybdenum oxide formed along the sidewalls of the trench may be generated. The thickness of the molybdenum oxide layer proximate to the upper region of the trench may differ by about 30% or less in thickness from the molybdenum oxide layer proximate to the lower region of the trench. The substrate may further include a molybdenum-containing metal region and a second liner disposed adjacent to the molybdenum-containing first liner. The method may further include supplying a fluorine-containing precursor to the semiconductor processing chamber, forming a plasma of the fluorine-containing precursor to generate fluorine-containing plasma wastewater, contacting the second liner with the fluorine-containing plasma wastewater to form a fluorinated portion of the second liner, supplying a chlorine-containing precursor to the semiconductor processing chamber, forming a plasma of the chlorine-containing precursor to generate chlorine-containing plasma wastewater, and contacting the fluorinated portion of the second liner with the chlorine-containing plasma wastewater. By the contact, the fluorinated portion of the second liner may be removed. Contacting the molybdenum-containing first liner with the plasma wastewater of the oxygen-containing precursor and contacting the oxidized portion of molybdenum with the plasma wastewater of the halogenated precursor may be repeated at least twice.

[0008] Some embodiments of the present technology include a semiconductor processing method. The method may include i) forming a plasma waste water of an oxygen-containing precursor. The method may include ii) contacting a molybdenum-containing first liner connecting at least two molybdenum-containing metal regions disposed in a plurality of recesses defined by at least one column of trenches with the plasma waste water of the oxygen-containing precursor. By the contact, an oxidized portion of molybdenum may be formed on the molybdenum-containing first liner. The method may include iii) forming a plasma waste water of a fluorine-containing precursor. The method may include iv) contacting the oxidized portion of molybdenum with the plasma waste water of the fluorine-containing precursor. By the contact, the oxidized portion of molybdenum may be removed.

[0009]

[0009] In some embodiments, steps i) through iv) may be repeated at least twice. The oxygen-containing precursor may be, or may include, ozone. The fluorine-containing precursor may be, or may include, tungsten hexafluoride. During steps i) and ii), the temperature may be maintained from about 200 °C to about 600 °C. During steps i) and ii), the pressure may be maintained at about 20 Torr or less. The method may include adjusting the temperature, pressure, or both, before contacting the oxidized portion of molybdenum with the plasma effluent of the fluorine-containing precursor. The second liner may be disposed adjacent to the molybdenum-containing metal region and the molybdenum-containing first liner. The method may further include forming a plasma of the fluorine-containing precursor to generate a fluorine-containing plasma effluent. The fluorine-containing precursor may be, or may include, nitrogen trifluoride. The method may further include contacting the second liner with the fluorine-containing plasma effluent to form a fluorinated portion of the second liner, and forming a plasma of a chlorine-containing precursor to generate a chlorine-containing plasma effluent. The chlorine-containing precursor may be, or may include, boron trichloride. The method may further include contacting the fluorinated portion of the second liner with the chlorine-containing plasma effluent. By the contact, the fluorinated portion of the second liner may be removed. The second liner may be, or may include, an oxygen-containing material, a nitrogen-containing material, or an oxygen-nitrogen-containing material.

[0010]

[0010] Some embodiments of the present technology include a semiconductor structure. The structure may include a substrate. The structure may include a silicon-containing material covering the substrate. The substrate may include trenches formed between columns. At least one column may define a plurality of recesses. The structure may include a liner extending within the plurality of recesses along at least one column. The structure may include a molybdenum-containing metal region formed within the plurality of recesses. The molybdenum-containing metal region may be partially surrounded by the liner. The thickness of the molybdenum-containing metal region in the recesses proximate to the upper region of the trench may differ by about 30% or less from the thickness of the molybdenum-containing metal region in the recesses proximate to the lower region of the trench.

[0011]

[0011] In some embodiments, the trench may be characterized by a depth of about 5 μm or more. The molybdenum-containing metal region may be surrounded on three sides by a liner. The molybdenum-containing metal region within one recess may be separated from the molybdenum material of the remaining plurality of recesses.

[0012]

[0012] The above technique may provide a number of advantages over conventional systems and techniques. For example, the process may provide uniform etching from the top to the bottom of the molybdenum-containing metal inside the trench. These embodiments and other embodiments will be described in more detail below in conjunction with their many advantages and features and the following description and the accompanying figures.

[0013]

[0013] By referring to the remainder of the specification and the drawings, the nature and advantages of the disclosed technology can be further understood.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Figure 5A - B

Figure 5C - D

Figure 6

Figure 7A - B

Figure 7C - D

Embodiments for Carrying Out the Invention

[0015]

[0022] Some of the drawings are included as schematic views. It should be understood that the figures are for illustrative purposes and should not be considered to be to scale unless the scale is specified. Further, as schematic views, the figures are provided to assist understanding and may not include all aspects or information compared to a realistic representation, and may include exaggerated materials for illustrative purposes.

[0016]

[0023] In the accompanying drawings, similar components and / or features may be labeled with the same reference numerals. Further, various components of the same type can be distinguished by attaching characters that distinguish the similar components after the reference label. When only the first reference label is used in this specification, the description is applicable to any one of the similar components having the same first reference label regardless of the characters.

[0017]

[0024] Due to the increasing demand for mobile computing and data centers, the need for high-capacity and high-performance NAND flash technology continues to grow. Since planar NAND is approaching the limit of practical scaling, 3D NAND is replacing 2D NAND for memory devices. The manufacture of 3D NAND structures requires depositing alternating layers of two or more materials. For example, in some structures, among other combinations, alternating layers of silicon dioxide and silicon, or silicon dioxide and silicon nitride, or silicon dioxide and molybdenum, with a total stack thickness of up to several microns, can be used. These stacks can be etched into trenches or contact holes. Further, one of these two alternating materials, or at least a part thereof, can be selectively etched from the trench to form a memory cell. For example, in an alternating layer of silicon dioxide and silicon, or silicon dioxide and silicon nitride, or silicon dioxide and molybdenum, the respective material that needs to be at least partially removed is silicon, silicon nitride, or molybdenum. When using a liner material such as a liner of aluminum oxide, hafnium oxide, titanium nitride, tantalum nitride, or hafnium nitride formed between silicon dioxide and molybdenum during stack formation, the liner may also need to be removed.

[0018]

[0025] In the transition from 2D NAND to 3D NAND, many process steps, such as the etching process for forming memory cells, are changed from vertical processes to horizontal processes. Further, in the 3D NAND structure, as the number of cells to be formed increases, the aspect ratios of trenches, contact holes, and other structures become higher, sometimes dramatically so. Due to the high aspect ratio of the trenches (greater than 10:1), a common challenge includes etching materials such as the above-mentioned molybdenum and liner materials uniformly from the top to the bottom within the feature. For such applications, wet processes have conventionally been used, but in wet etching, the material may be etched more than necessary or desired. For example, wet etching may significantly etch each layer and may etch each layer almost completely down to other memory holes, making it more difficult to place the cell layers in the appropriate or desired positions and potentially weakening the structure and causing deformation. Further, as the size of the structure continues to shrink, problems of pattern collapse or sticking may occur due to the surface tension of the fluid used in wet etching.

[0019]

[0026] Conventional plasma dry etching has also been considered for these applications. Since plasma etching can be anisotropic and directional, it can be used to remove the materials at the top and bottom of the trenches, but it may be difficult to uniformly recess the sidewalls of the memory holes in some cases. Plasma dry etching can be combined with wet etching, where one etches the top and bottom and the other etches the sidewalls. However, in this case, two processes are required, increasing the processing time and cost.

[0020]

[0027] This technique overcomes these problems by performing a dry etching process that enables uniform etching from the top to the bottom of the molybdenum-containing metal and / or liner material inside the high aspect ratio trench. By oxidizing the molybdenum-containing metal, an oxide layer of substantially uniform thickness can be formed from the top to the bottom of the trench. Then, by supplying a halogen precursor and selectively etching only the layer oxidized in the previous oxidation step, uniform etching of the molybdenum-containing metal from the top to the bottom inside the trench can be achieved. Similarly, by treating the liner material with fluorine, a fluoride layer of substantially uniform thickness can be formed from the top to the bottom of the trench. Then, by supplying a chlorine precursor and selectively etching only the layer oxidized in the previous oxidation step, uniform etching of the liner material from the top to the bottom inside the trench can be achieved.

[0021]

[0028] The remaining disclosure always specifies a particular etching process using the disclosed technique, but it will be readily understood that the systems and methods are equally applicable to deposition and cleaning processes that can be performed in the described chamber. Accordingly, the present technology should not be considered limited to use only in an etching process or chamber. Further, although an exemplary chamber has been described to provide a basis for the present technology, it should be understood that the present technology can be applied to virtually any semiconductor processing chamber that can enable the described processes.

[0022]

[0029] FIG. 1 is a top view showing one embodiment of a processing system 100 for deposition, etching, baking, and curing chambers according to an embodiment. In the figure, a pair of front-opening unified pods (FOUPs) 102 are received by a robot arm 104 and placed in a low-pressure holding area 106 before being placed inside one of the substrate processing chambers 108a-f positioned in tandem sections 109a-c, supplying substrates of various sizes. A second robot arm 110 is used to reciprocally transport the substrate wafers from the holding area 106 to the substrate processing chambers 108a-f. Each substrate processing chamber 108a-f can be equipped to perform a number of substrate processing steps including, in addition to cyclic layer deposition (CLD), atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), etching, pre-cleaning, degassing, orientation, and other substrate processes, the dry etching processes described herein.

[0023]

[0030] The substrate processing chambers 108a-f can include one or more system components for depositing a dielectric or metal film on a substrate wafer, annealing, curing, and / or etching a dielectric or metal film on a substrate wafer. In one configuration, two pairs of processing chambers, e.g., 108c-d and 108e-f, can be used to deposit material on the substrate, and a third pair of processing chambers, e.g., 108a-b, can be used to etch the deposited material. In another configuration, all three pairs of chambers, e.g., 108a-f, can be configured to etch a dielectric or metal film on the substrate. Any one or more of the described processes can be performed in a chamber(s) separate from the manufacturing system shown in different embodiments. It will be understood that additional configurations of deposition, etching, annealing, and curing chambers for dielectric films are also envisioned by the system 100.

[0024]

[0031] FIG. 2A is a cross-sectional view showing an exemplary process chamber system 200 having a plasma generation region partitioned within a process chamber. For example, during film etching of titanium nitride, tantalum nitride, molybdenum, tungsten, copper, cobalt, silicon, polysilicon, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, etc., a process gas can be supplied to a first plasma region 215 through a gas inlet assembly 205. A remote plasma system (RPS) 201 may optionally be included in the system and can then process a first gas that moves through the gas inlet assembly 205. The gas inlet assembly 205 may include two or more individual gas supply channels, and a second channel (not shown) can bypass the RPS 201 if the RPS 201 is included.

[0025]

[0032] A pedestal 265 having a cooling plate 203, a face plate 217, an ion suppressor 223, a showerhead 225, and a substrate 255 disposed thereon is shown, each of which may be included according to an embodiment. The pedestal 265 may have a heat exchange channel through which a heat exchange fluid flows to control the temperature of the substrate and operates to heat and / or cool the substrate or wafer during a processing step. The wafer support platter of the pedestal 265, which may include aluminum, ceramic, or a combination thereof, can be resistively heated using an embedded resistive heating element to achieve a relatively high temperature, such as from about 100°C or less to about 600°C or more.

[0026]

[0033] The face plate 217 may be pyramid-shaped, cone-shaped, or other similar structures where the narrow upper part expands to the wide bottom. The face plate 217 may further be flat as shown and includes a plurality of through channels used to distribute the process gas. Plasma generation gas and / or plasma excitation species can pass through the plurality of holes shown in FIG. 2B of the face plate 217 for more uniform delivery into the first plasma region 215 depending on the use of the RPS 201.

[0027]

[0034] The exemplary configuration may include a gas inlet assembly 205 that opens into a gas supply region 258 partitioned from the first plasma region 215 by a faceplate 217 such that gas / species flows through holes in the faceplate 217 into the first plasma region 215. The structural and operational characteristics may be selected to prevent significant backflow of plasma from the first plasma region 215 into the gas supply region 258, the gas inlet assembly 205, and back into the fluid supply system 210. The faceplate 217, or the conductive top of the chamber, and the showerhead 225 are shown with an insulating ring 220 positioned therebetween and enabling an alternating potential to be applied to the faceplate 217 relative to the showerhead 225 and / or the ion suppressor 223. The insulating ring 220 may be positioned between the faceplate 217 and the showerhead 225 and / or the ion suppressor 223, enabling a capacitively coupled plasma (CCP) to be formed in the first plasma region. A baffle (not shown) may further be positioned in the first plasma region 215 or otherwise coupled to the gas inlet assembly 205 and can affect the flow of fluid into the region through the gas inlet assembly 205.

[0028]

[0035] Ion suppressor 223 may include a plate or other shaped dimension that defines a plurality of apertures throughout the structure, configured to suppress the movement of ion-charged species out of the first plasma region 215 while allowing neutral or radical species that are not charged to pass through the ion suppressor 223 and reach the activated gas delivery region between the suppressor and the showerhead. In embodiments, the ion suppressor 223 may include a porous plate having various aperture configurations. These uncharged species may include highly reactive species that are transported through the apertures along with a less reactive carrier gas. As described above, the movement of ionic species through the pores can be reduced and, in some cases, completely suppressed. By controlling the amount of ionic species passing through the ion suppressor 223, the control over the mixed gas contacting the underlying wafer substrate can be advantageously improved, and as a result, the control over the deposition and / or etching characteristics of the mixed gas can be improved. For example, by adjusting the ion concentration of the mixed gas, its etching selectivity, such as the SiNx:SiOx etching ratio, Si:SiOx etching ratio, etc., can be significantly changed. In alternative embodiments where deposition is performed, the balance between conformal deposition and flowable deposition of the dielectric material can also be shifted.

[0029]

[0036] The plurality of apertures of the ion suppressor 223 can be configured to control the passage of the activated gas through the ion suppressor 223, i.e., ionic species, radical species, and / or neutral species. For example, the aspect ratio of the pores, or the diameter of the pores relative to the length of the pores, and / or the shaped dimensions of the pores can be controlled such that the flow of ion-charged species in the activated gas passing through the ion suppressor 223 is reduced. The pores of the ion suppressor 223 can include a tapered portion facing the plasma excitation region 215 and a cylindrical portion facing the showerhead 225. The cylindrical portion can be shaped and dimensioned to control the flow of ionic species sent to the showerhead 225. An adjustable electrical bias can also be applied to the ion suppressor 223 as an additional means of controlling the flow of ionic species through the suppressor.

[0030]

[0037] The ion suppressor 223 can function to reduce or remove the amount of ionized charged species moving from the plasma generation region to the substrate. The uncharged neutral and radical species can pass through the opening of the ion suppressor and react with the substrate. It should be noted that in some embodiments, complete removal of the ionized charged species in the reaction region surrounding the substrate may not be performed. In some cases, the ionic species are intended to reach the substrate to perform an etching and / or deposition process. In such cases, the ion suppressor can help control the concentration of ionic species in the reaction region at a level that aids the process.

[0031]

[0038] Combining the showerhead 225 with the ion suppressor 223 can avoid the plasma present in the first plasma region 215 directly exciting the gas within the substrate processing region 233, while enabling the excited species to move from the chamber plasma region 215 into the substrate processing region 233. In this way, the chamber can be configured to prevent the plasma from contacting the substrate 255 being etched. Thereby, various complex structures and films patterned on the substrate, which may be damaged, dislocated, or distorted in other ways if directly contacted by the generated plasma, can be advantageously protected. Further, when the plasma is brought into contact with or close to the substrate level, the etching rate of oxide species may increase. Therefore, when the exposed region of the material is an oxide, this material can be further protected by maintaining the plasma away from the substrate.

[0032]

[0039] The processing system may further include a power supply 240 electrically coupled to the processing chamber to supply power to the faceplate 217, the ion suppressor 223, the showerhead 225, and / or the pedestal 265 to generate plasma in the first plasma region 215 or the substrate processing region 233. The power supply may be configured to deliver an adjustable amount of power to the chamber depending on the process being performed. Such a configuration may enable the use of adjustable plasma in the process being performed. Different from remote plasma units, which are often given an on or off function, adjustable plasma may be configured to deliver a specific amount of power to the plasma region 215. As a result, it may be possible to develop specific plasma characteristics that dissociate precursors in a specific manner and improve the etching profiles generated by these precursors.

[0033]

[0040] Plasma can be ignited either in the chamber plasma region 215 above the showerhead 225 or in the substrate processing region 233 below the showerhead 225. For example, plasma may be present in the chamber plasma region 215 to generate radical precursors from the inflow of fluorine-containing precursors or other precursors. Typically, an alternating voltage in the radio frequency (RF) range is applied between the conductive upper part of the processing chamber, such as the faceplate 217, and the showerhead 225 and / or the ion suppressor 223 to ignite plasma in the chamber plasma region 215 during deposition. The RF power supply may generate a high RF frequency of 13.56 MHz, but other frequencies can also be generated alone or in combination with the 13.56 MHz frequency.

[0034]

[0041] Figure 2B is a detailed view 253 showing features affecting process gas distribution through faceplate 217. As shown in FIGS. 2A and 2B, faceplate 217, cooling plate 203, and gas inlet assembly 205 intersect to define a gas supply region 258 through which process gas can be delivered from gas inlet assembly 205. The gas can fill the gas supply region 258 and flow through apertures 259 in faceplate 217 into the first plasma region 215. The apertures 259 can be configured to direct flow substantially in one direction, thereby allowing process gas to flow into substrate processing region 233 but partially or completely preventing backflow into gas supply region 258 after crossing faceplate 217.

[0035]

[0042] A gas distribution assembly such as showerhead 225 for use in process chamber section 200 can be referred to as a dual-channel showerhead (DCSH) and is described in further detail in the embodiment depicted in FIG. 3. The dual-channel showerhead can provide an etching process that separates etchant outside of substrate processing region 233 and limits chamber components and their interaction with each other before being delivered into the processing region.

[0036]

[0043] Showerhead 225 can include an upper plate 214 and a lower plate 216. The plates can be coupled to each other to define a region 218 therebetween. The plates can be coupled to provide a first fluid channel 219 through the upper and lower plates and a second fluid channel 221 through lower plate 216. The channels formed can be configured to provide fluid access from region 218 through only the second fluid channel 221 through lower plate 216, and the first fluid channel 219 can be fluidly separated from region 218 between the plates and the second fluid channel 221. Region 218 can be fluidly accessible through the side of showerhead 225.

[0037]

[0044] FIG. 3 is a bottom view of a showerhead 325 for use with a processing chamber according to an embodiment. The showerhead 325 may correspond to the showerhead 225 shown in FIG. 2A. The through holes 365, which are illustrations of the first fluid channels 219, may have a plurality of shapes and configurations to control and affect the flow of the precursor through the showerhead 225. The small holes 375, which are illustrations of the second fluid channels 221, may be substantially evenly distributed on the surface of the showerhead among the through holes 365 and may help obtain a more even mixing of the precursor when exiting the showerhead than other configurations.

[0038]

[0045] The chamber described above can be used to perform an exemplary method including an etching method. Refer to FIG. 4 showing exemplary steps in a method 400 according to an embodiment of the present technology. Before the first step of the method 400, the substrate can be processed in one or more ways. For example, an inter-poly dielectric (IPD) layer can be formed on the substrate. The IPD layer may include any number of materials and may include alternating layers of a placeholder material and a dielectric material. In an embodiment, the dielectric material may be silicon oxide or may include silicon oxide, and the placeholder material may be silicon nitride or may include silicon nitride. One or more trenches or memory holes may be formed through the stacked IPD layer, and the trenches may divide the IPD layer into columns for further processing into a 3D NAND structure. For example, a layer of the placeholder material or at least a portion thereof can be removed to form a lateral recess along the sidewalls of the columns. Next, the lateral recess can be lined with a gate dielectric and filled with a gate metal to form a gate structure of the 3D NAND. In an embodiment, the gate dielectric may be aluminum oxide or may include aluminum oxide, and the gate metal may be molybdenum, tungsten, cobalt, or any other conductive material or may include these.

[0039]

[0046] A gate metal barrier can also be formed between the gate metal and the gate dielectric and / or between the gate metal and the dielectric material of the IPD layer. The gate metal barrier may be or may include a metal, metal oxide, or metal nitride such as hafnium, titanium, tantalum, aluminum oxide, hafnium oxide, hafnium nitride, titanium nitride, tantalum nitride, etc. Usually, the gate metal can be deposited from top to bottom in a lateral recess formed along the inside and sidewalls of the trench to form a metal region intervening between the dielectric material layers of the IPD layer. During deposition, the gate metal can also be deposited outside the lateral recess to line a part of the sidewall of the trench and connect the metal regions. Such lining or connecting metal can be removed so as to separate the metal regions from each other to prevent crosstalk or short circuit between cells. Part or all of the process can be performed in a chamber or system tool that may include one or more chambers in which the steps of method 400 are performed to remove the connecting metal lining the sidewalls of the trench as described above, or can be performed in different chambers on the same system tool.

[0040]

[0047] Next, the steps of method 400 will be described in conjunction with the schematic diagrams of FIGS. 5A - 5D. FIG. 5A illustrates a portion of a processed structure 500 that is further developed in the manufacture of a 3D NAND structure. The processed structure 500 can include one or more trenches 505 (only one shown) formed between adjacent vertical columns 510 of a stack covering a substrate 515. The stack can include a dielectric layer and a metal layer or metal region interposed between the dielectric layers to form the gate structure of each memory cell. The dielectric layer can include an oxide layer such as silicon oxide layer 520 as shown in FIG. 5A. The metal region can include a molybdenum region such as molybdenum region 525 as shown in FIG. 5A. The molybdenum region 525 can be formed by depositing molybdenum in a lateral recess 527 formed by removing a layer or a portion of a placeholder material. When forming the molybdenum region 525, molybdenum can also be deposited along the top 530, bottom 535, and sidewalls 540 of the trench 505, and two or more of the molybdenum regions 525 can be connected. The processed structure 500 can further include one or more barrier materials or liner materials such as a gate metal barrier and a gate dielectric, which can be collectively or individually referred to as a second liner. The gate metal barrier can include an oxide, nitride, or oxygen - nitrogen barrier such as oxide or nitride barrier 545 (e.g., aluminum oxide, hafnium oxide, titanium nitride, tantalum nitride, hafnium nitride, etc.) as shown in FIG. 5A. The oxide or nitride barrier, also referred to as the second liner, can be disposed adjacent to the molybdenum - containing metal region and / or the molybdenum - containing first liner. The gate dielectric can include an aluminum oxide gate dielectric such as gate dielectric 550 (e.g., aluminum oxide) as shown in FIG. 5A. The oxide or nitride barrier 545 can be a metal - containing oxide or nitride material. It is contemplated that the processed structure 500 can include only one of the oxide or nitride barrier 545 and the gate dielectric 550.

[0041]

[0048] Although FIG. 5A shows only four layers of dielectric material and four layers of metal, the processed structure 500 can include any number of layers of each material, such as up to about 10 or more, about 15 or more, about 20 or more, about 25 or more, about 30 or more, about 35 or more, about 40 or more, about 45 or more, about 50 or more, about 55 or more, about 60 or more, about 65 or more, about 70 or more, about 80 or more, about 90 or more, about 100 or more, or more. As a result, trenches can be formed having a width of several hundred nanometers, or several tens of nanometers, or less, and a height of several microns, or several tens of microns, or more. Consequently, the aspect ratio or the ratio of height to width of the trenches can be greater than 20:1, greater than 50:1, greater than 75:1, greater than 100:1, or more. In embodiments, the trenches can be characterized by a width of about 200 nm or less, and / or a depth of about 5 microns or more. As described above, the molybdenum-containing material formed on the bottom and / or sidewalls of the trenches can be removed to separate the molybdenum regions from each other. Due to the high aspect ratio of the trenches, it is difficult to uniformly etch the molybdenum metal from the top to the bottom of the trenches, which is also said to have a filling ratio of 1:1 between the top and the bottom, using conventional dry etching methods. As will be described in more detail below, the method 400 according to some embodiments of the present technology can improve the filling from the top to the bottom and achieve substantially uniform etching of the molybdenum metal inside the trenches.

[0042]

[0049] As shown in FIG. 5B, method 400 may include first oxidizing a molybdenum-containing first liner formed on top 530, bottom 535, and / or sidewall 540 of trench 505 to form molybdenum oxide 555 inside and on top of trench 505. In some embodiments, to oxidize molybdenum, substrate 515 may be positioned within a processing region of a semiconductor processing chamber, such as substrate processing region 233 of processing chamber system 200 described above with reference to FIG. 2A. Once positioned within the processing region, method 400 can be initiated in step 405 by supplying an oxygen-containing precursor to a remote plasma region of the semiconductor processing chamber. The remote plasma region may be fluidly coupled to the processing region, but may be physically separated to limit substrate-level plasma that could damage exposed structures or materials on substrate 515. In some embodiments, the remote plasma region may include a remote plasma system (RPS) fluidly coupled to an inlet to the semiconductor processing chamber, such as RPS 201 described above. In some embodiments, the remote plasma region may include a capacitively coupled plasma (CCP) region, such as first plasma region 215 formed by capacitively coupling faceplate 217 to showerhead 225 and / or ion suppressor 223, and the CCP region may be physically separated from the processing region by one of its electrodes, such as showerhead 225 and / or ion suppressor 223. Method 400 may further include forming a plasma of the oxygen-containing precursor to generate oxygen-containing plasma effluent in step 410 and supplying the oxygen-containing plasma effluent to the processing region in step 415. In step 420, the molybdenum connecting molybdenum region 525 can be oxidized to form molybdenum oxide 555 inside and on top of trench 505, as shown in FIG. 5B.

[0043]

[0050] The oxygen-containing precursor may include various fluids and may include one or more of atomic oxygen, molecular oxygen (O2), N2O, NO, NO2, CO2, ozone (O3), or any other oxygen-containing precursor that can similarly perform an oxidation process. The oxygen-containing precursor can be supplied at a rate of at least 1000 sccm, and in embodiments, can be supplied at a rate of about 2000 sccm or more, about 3000 sccm or more, about 4000 sccm or more, about 5000 sccm or more, about 6000 sccm or more, about 7000 sccm or more, about 8000 sccm or more, about 9000 sccm or more, or more than that. In some embodiments, the flow of the oxygen-containing precursor may be pulsed. The flow of the oxygen-containing precursor may be pulsed over a time of about 60 seconds or less in embodiments, about 55 seconds or less, about 50 seconds or less, about 45 seconds or less, about 40 seconds or less, about 35 seconds or less, about 30 seconds or less, about 25 seconds or less, about 20 seconds or less, about 15 seconds or less, about 10 seconds or less, about 5 seconds or less.

[0044]

[0051] While the oxygen-containing precursor is flowing, the flow rate of the oxygen-containing precursor can be maintained at a relatively high level so that there can be sufficient oxygen, or more than sufficient oxygen, from the top to the bottom of the trench to completely oxidize the molybdenum connecting the molybdenum regions. In some embodiments, by supplying sufficient oxygen, the uniformity of the thickness of the molybdenum oxide layer formed inside the trench can be further improved. This uniformity may in part be due to the initial rapid oxidation that occurs on a suitable or clean molybdenum surface. Specifically, method 400 can be performed after the molybdenum has been deposited inside the trench and before it is exposed to the atmosphere. The oxidation rate of a suitable molybdenum surface will be rapid enough with sufficient oxygen supply to oxidize the molybdenum near the bottom of the trench to a thickness that can be substantially the same as the thickness of the oxidized molybdenum near the top of the trench almost simultaneously. As the oxidation penetrates the surface of the metal, the oxidation rate can drop dramatically, and in some embodiments, it may reach a saturation depth where only minimal oxidation or no further oxidation can continue under the chamber conditions. Thus, even though the residence time is long at a location near the top of the trench, the metal located away from the initial contact of the plasma wastewater, such as at the bottom of the trench, can be oxidized to a depth similar to or substantially the same as that of the top of the trench.

[0045]

[0052] In some embodiments, the initial rapid oxidation can produce a molybdenum oxide layer having a thickness of about 10 Å or more, about 15 Å or more, about 20 Å or more, about 25 Å or more, about 30 Å or more, about 35 Å or more, about 40 Å or more, about 50 Å or more, about 60 Å or more, about 70 Å or more, about 80 Å or more, about 90 Å or more, about 100 Å or more, or more, before the oxidation process slows down. In some embodiments, by adjusting the processing conditions, the initial rapid oxidation can produce a molybdenum oxide layer having a thickness of about 100 Å or less, about 90 Å or less, about 80 Å or less, about 70 Å or less, about 60 Å or less, about 50 Å or less, about 40 Å or less, or less. In embodiments, the thickness of the molybdenum oxide layer adjacent to the upper region of the trench may differ from the thickness of the molybdenum oxide layer adjacent to the lower region of the trench by about 30% or less, about 25% or less, about 20% or less, about 15% or less, about 10% or less, about 5% or less, about 3% or less, about 1% or less, or less. Thus, as shown in FIG. 5B, a top-to-bottom fill ratio of molybdenum oxidation of about 1.3:1 or less, about 1.25:1 or less, about 1.2:1 or less, about 1.15:1 or less, about 1.1:1 or less, about 1.05:1 or less, or a ratio that is substantially or essentially 1:1 can be achieved using method 400. Considering the initial rapid oxidation, the flow of the oxygen-containing precursor can be maintained for a time of about 15 minutes or less, about 10 minutes or less, about 5 minutes or less, about 3 minutes or less, about 2 minutes or less, about 90 seconds or less, about 60 seconds or less, about 50 seconds or less, about 40 seconds or less, about 30 seconds or less, about 25 seconds or less, about 20 seconds or less, about 15 seconds or less, about 10 seconds or less, about 5 seconds or less, or less. In some embodiments, to promote sufficient oxidation, the flow of the oxygen-containing precursor can be maintained for a time of about 5 seconds or more, about 10 seconds or more, about 30 seconds or more, about 1 minute or more, about 5 minutes or more, about 10 minutes or more, about 15 minutes or more, or more. Thus, in some embodiments, the flow of the oxygen-containing precursor can be maintained for a time from about 5 seconds to about 15 minutes, from about 30 seconds to about 10 minutes, from about 1 minute to about 5 minutes, or any other suitable time.

[0046]

[0053] The oxygen-containing precursor may also include any number of carrier gases, which may include nitrogen, helium, argon, or other noble gases, inert gases, or useful precursors. The carrier gas can be used to improve the uniform distribution of the oxygen-containing precursor inside the trench, thereby further improving the top-to-bottom filling for the oxidation process 420. In some embodiments, the flow rate of the carrier gas can be maintained at about 50% or less of the flow rate of the oxygen-containing precursor, or about 40% or less, about 30% or less, about 20% or less, about 10% or less, about 5% or less, about 3% or less, or about 1% or less, or less than that of the flow rate of the oxygen-containing precursor. By adjusting the composition of the components of the oxygen-containing precursor and / or their respective flow rates, uniform delivery of the oxygen-containing plasma wastewater inside the trench can be achieved, thereby further improving the uniformity of molybdenum oxidation from the top to the bottom of the trench.

[0047]

[0054] Other process conditions such as plasma output, process temperature, process pressure, etc. may also affect the uniformity of molybdenum oxidation from the top to the bottom of the trench. In embodiments where the oxygen-containing plasma can be formed in a remote plasma system, the plasma output can be about 2000 W or less, about 1500 W or less, about 1000 W or less, about 750 W or less, about 500 W or less, about 250 W or less, or less than that, in order to promote the dissociation of the oxygen-containing precursor. In embodiments where the oxygen-containing plasma can be formed in the capacitively coupled plasma (CCP) region of a semiconductor processing chamber, a lower plasma output can be used to prevent damage to the structures on the substrate. The plasma output in the CCP region can be at least 50 W, and in embodiments, it can be about 100 W or more, about 150 W or more, about 200 W or more, about 250 W or more, about 300 W or more, about 350 W or more, about 400 W or more, about 450 W or more, about 500 W or more, or more than that. The plasma output in the CCP region can be about 2500 W or less, about 2000 W or less, about 1500 W or less, about 1000 W or less, about 750 W or less, about 500 W or less, about 250 W or less, or less than that.

[0048]

[0055] To promote rapid oxidation and thereby improve filling from top to bottom, the temperature in the processing chamber or at the substrate level can be maintained at about 200°C to about 600°C in embodiments. The temperature can be maintained at about 200°C or higher, at about 250°C or higher, at about 300°C or higher, at about 350°C or higher, at about 400°C or higher, at about 450°C or higher, at about 500°C or higher, at about 550°C or higher, at about 600°C or higher, or higher. The higher the temperature maintained during the oxidation step 420, the faster molybdenum can oxidize, and the thickness of the molybdenum oxide layer can be more uniform. During the oxidation step 420, the pressure in the processing chamber can be maintained at about 20 Torr or less in embodiments. The pressure can be maintained at about 15 Torr or less, at about 10 Torr or less, at about 5 Torr or less, at about 4 Torr or less, at about 3 Torr or less, at about 2 Torr or less, at about 1 Torr or less, at about 100 mTorr or less, or less. In embodiments, the pressure can be maintained from about 500 mTorr to about 10 Torr. By maintaining the pressure inside the processing chamber relatively low, the distribution of the oxygen-containing plasma wastewater into the trenches is promoted, and as a result, uniform oxidation from top to bottom can be achieved as described above.

[0049]

[0056] Although FIG. 4 illustrates oxidizing molybdenum and / or the liner material using an oxygen-containing plasma, a non-plasma process can also be used. Thus, in some embodiments, steps 410 and 415 of method 400 can be omitted. An oxygen-containing precursor such as one or more of atomic oxygen, molecular oxygen (O2), ozone (O3), or other oxygen-containing precursors can be supplied to the processing region to oxidize the molybdenum and / or the liner material. In embodiments where molecular oxygen can be used to oxidize the molybdenum and / or the liner material, the temperature in the processing chamber or at the substrate level can be maintained at about 250°C to about 600°C. The temperature can be maintained at about 250°C or higher, at about 300°C or higher, at about 350°C or higher, at about 400°C or higher, at about 450°C or higher, at about 500°C or higher, at about 550°C or higher, at about 600°C or higher, or higher. In embodiments where ozone can be used to oxidize the molybdenum and / or the liner material, ozone can be generated using an ozone generator that is fluidly coupled to the inlet of the processing chamber.

[0050]

[0057] In some embodiments, under sufficient supply of the oxygen-containing precursor and appropriate process conditions, substantially all of the molybdenum-containing first liners formed on the sidewalls of the trench 505 can be oxidized, and as shown in FIG. 5C, a part of the molybdenum region 525 inside the lateral recess 527 of the trench 505 can also be oxidized. By slightly etching the molybdenum inside the lateral recess 527, the molybdenum region 525 can be reliably separated when removing the oxidized molybdenum in subsequent steps of the method 400. As also shown in FIG. 5C, during the oxidation step 420, when the oxide or nitride barrier 545 contains nitride, the portion of the oxide or nitride barrier 545 in contact with the oxidized molybdenum 555 is also oxidized, and an oxidized portion of the nitride barrier 560 can be formed.

[0051]

[0058] In some embodiments, when the molybdenum-containing first liner formed on at least a portion of the sidewall 540 of the trench 505 oxidizes together with a part of the molybdenum region 525, the oxidation process 420 can be temporarily stopped by stopping the flow of the oxygen-containing precursor. In an embodiment, the residual plasma wastewater can be purged before the step 425. In the step 425, a halogenated precursor can be supplied to the processing region. The halogenated precursor can include a metal halide or other halogen-containing precursor that can interact with the molybdenum oxide and / or the liner material. In an embodiment, the halogenated precursor can be a chlorine-containing precursor or a fluorine-containing precursor, or can include a chlorine-containing precursor or a fluorine-containing precursor. The halogenated precursor can include tungsten chloride such as tungsten pentachloride, and / or tungsten fluoride such as tungsten hexafluoride. In the step 430, the halogenated precursor can modify the molybdenum oxide 555, interact to form a volatile substance, and then can be removed from the chamber. The volatile substance formed from the halogenated precursor and the molybdenum oxide 555 may include molybdenum oxychloride and / or molybdenum oxyfluoride. When the molybdenum oxide 555 is removed by the halogenated precursor, the underlying oxide or nitride barrier 545 that can be oxidized as described above can be exposed. The exposed portion of the oxide or nitride barrier 545 can interact with the halogenated precursor without being oxidized first, but when the oxide or nitride barrier 545 oxidizes to form an oxidized portion of the nitride barrier 560, the etching rate can be improved.

[0052]

[0059] The etching rate of the oxidized portion of the liner material by the halogenated precursor can be at least about 2 times, about 3 times, about 4 times, about 5 times, about 6 times, about 7 times, about 8 times, or more than that of the non-oxidized portion of the liner material by the halogenated precursor. The volatile substances formed from the halogenated precursor and the oxidized portion of the nitride barrier 560 may include metal chlorides such as metal oxy chlorides, metal oxy fluorides, metal tetrachlorides, and / or metal fluorides such as metal tetrafluorides. The halogenated precursor can be delivered over a time period of from about 15 seconds to about 5 minutes during step 425. In embodiments, the delivery of the halogenated precursor can continue for at least about 30 seconds, 1 minute, 1.5 minutes, 2 minutes, 2.5 minutes, 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, 5 minutes, or longer to ensure complete removal of the oxidized portion of the molybdenum oxide 555 and / or the nitride barrier 560. As shown in FIG. 5D, the oxidized portion of the molybdenum oxide 555 and / or the nitride barrier 560 can be removed at the completion of the etching step 430, and the molybdenum regions 525 can be separated from each other.

[0053]

[0060] In the etching step 430, the oxidized portions of the molybdenum oxide 555 and the nitride barrier 560 can be selectively removed with respect to other materials and structures on the substrate, including the molybdenum region 525, the oxide or nitride barrier 545 intervening between the molybdenum region 525 and the gate dielectric 550, and the gate dielectric 550. Without being bound by a particular theory, the bond between oxygen and metal in the gate dielectric may be stronger than the bond between oxygen and molybdenum and / or the bond between oxygen and metal in the gate dielectric, and in part, when there are reactive products, the gate dielectric 550 may not be etched by the halogenated precursor because it may contain metal fluorides and / or metal oxy fluorides that can be substantially non-volatile under the process conditions of the etching step 430. Although not explicitly shown in FIG. 5D, the method 400 can also selectively remove the oxidized portions of the molybdenum oxide 555 and the nitride barrier 560 with respect to silicon oxide such as the silicon oxide layer 520 and with respect to silicon nitride that may form the charge trap layer of the memory cell.

[0054]

[0061] The halogenated precursor can selectively etch only the molybdenum oxide 555 and / or the oxidized portion of the nitride barrier 560, and the oxidation step 420 can result in a substantially uniform fill from top to bottom as described above. Therefore, the etching step 430 can also result in a substantially uniform fill from top to bottom. The etched thickness of the molybdenum layer adjacent to the upper region of the trench can be, in an embodiment, about 30% or less, about 25% or less, about 20% or less, about 15% or less, about 10% or less, about 5% or less, about 3% or less, about 1% or less, or less than that different from the etched thickness of the molybdenum layer adjacent to the lower region of the trench etched by the method 400. Thus, a top-to-bottom fill ratio of molybdenum etching of about 1.3:1 or less, about 1.25:1 or less, about 1.2:1 or less, about 1.15:1 or less, about 1.1:1 or less, about 1.05:1 or less, or a ratio that is substantially or essentially 1:1 can be achieved using the method 400. Such a uniform fill from top to bottom can prevent or limit over-etching of the molybdenum region 525 inside the lateral recess 527 of the trench 505, facilitate complete removal of molybdenum that can deposit on the sidewalls 540 and / or bottom 535 of the trench 505, and reliably separate the molybdenum regions 525 from each other.

[0055]

[0062] Furthermore, by using a halogenated precursor as the etchant, the isotropic etching it can provide can further improve the filling from the top to the bottom. Compared to conventional reactive ion etching where the orientation is imparted and it becomes difficult to laterally etch the oxidized portion of the nitride barrier 560 that lines the sidewalls 540 of the molybdenum oxide 555 and / or the trench 505, the halogenated precursor can react substantially uniformly with the molybdenum oxide 555 and / or the oxidized portion of the nitride barrier 560 inside the trench 505. As a result, the molybdenum oxide 555 and / or the oxidized portion of the nitride barrier 560 inside the trench 505 are etched substantially isotropically. Such uniformity can be promoted by maintaining the pressure in the processing chamber at about 10 Torr or more, about 15 Torr or more, about 20 Torr or more, about 25 Torr or more, about 30 Torr or more, about 35 Torr or more, about 40 Torr or more, about 45 Torr or more, about 50 Torr or more, about 55 Torr or more, about 60 Torr or more, about 70 Torr or more, about 80 Torr or more, about 90 Torr or more, about 100 Torr or more, or more. By increasing the pressure in the processing chamber, the mean free path of the halogenated precursor can be decreased, achieving a non-directional flow of the halogenated precursor, thereby achieving isotropic etching in the trench. Alternatively, in some embodiments, during the etching step 430, the pressure in the processing chamber can be maintained at about 100 Torr or less, about 90 Torr or less, about 80 Torr or less, about 70 Torr or less, about 60 Torr or less, about 55 Torr or less, about 50 Torr or less, about 45 Torr or less, about 40 Torr or less, about 35 Torr or less, about 30 Torr or less, about 25 Torr or less, about 20 Torr or less, about 15 Torr or less, about 10 Torr or less, about 5 Torr or less, about 1 Torr or less, or less. Thus, in some embodiments, the method 400 can further include adjusting the process conditions (e.g., temperature, pressure, both, etc.) in the processing chamber between the oxidation step and the etching step. For example, in some embodiments, the pressure can be adjusted from about 5 Torr or less to about 10 Torr or more during oxidation.Any of the pressures or ranges described above can be used similarly during the two processes.

[0056]

[0063] As described above, in order to promote uniform oxidation, a relatively high temperature can be maintained within the processing chamber or at the substrate level during the oxidation step 420 of method 400. In some embodiments, a relatively low temperature can be maintained within the processing chamber or at the substrate level during the etching step 430. Since the by-products formed using the halogenated precursor are highly volatile, a high temperature may not be required to achieve effective etching. Further, a relatively low temperature can also limit or prevent the surface movement of non-volatile or low-volatile by-products that may be formed, such as aluminum fluoride described above. During the etching step 430, the temperature within the processing chamber or at the substrate level can be maintained at about 250°C to about 400°C. In some embodiments, the temperature can be maintained at about 400°C or less, and in embodiments, at about 350°C or less, about 300°C or less, about 250°C or less, or less. In some embodiments, a relatively high temperature can be maintained within the processing chamber or at the substrate level during the etching step 430 to increase the reaction rate. In some embodiments, the temperature maintained within the processing chamber or at the substrate level during the etching step 430 can be the same as or higher than the temperature maintained within the processing chamber or at the substrate level during the oxidation step 420. Thus, during the etching step 430, the temperature within the processing chamber or at the substrate level can be maintained at about 400°C or higher, about 450°C or higher, about 500°C or higher, about 550°C or higher, about 600°C or higher, or above.

[0057]

[0064] During the oxidation process 420 and the etching process 430, there can be several ways to maintain different temperatures within the processing chamber or at the substrate level. If the oxidation process 420 can be paused, the temperature within the processing chamber or at the substrate level can be lowered or raised to a desired level before starting the flow of the halogen precursor in step 425. Alternatively or additionally, in some embodiments, during the oxidation process 420, the substrate can be positioned near a heat source inside the processing chamber to achieve a relatively high temperature at the substrate level, and following the oxidation process 420, the substrate can be moved away from the heat source to lower the temperature at the substrate level for the etching process 430. For example, in some embodiments, the showerhead 225 can include a heater or can be configured to be heated. During the oxidation process, the substrate can be positioned close to the showerhead to raise the substrate and process temperature, and the substrate can be positioned at a first distance from the heat source. Following the oxidation process, the substrate can be translated parallel from the showerhead to a second distance from the heat source, such as by lowering the height of the pedestal, to reduce the heating effect. Then, when the substrate is moved, the etching process can be performed at a second temperature lower than the first temperature. In some embodiments where the etching process 430 can be performed at a higher temperature than the oxidation process 420, the substrate can be positioned further away from the heat source inside the processing chamber to achieve a relatively low temperature at the substrate level during the oxidation process 420, and following the oxidation process 420, the substrate can be moved closer to the heat source to raise the temperature at the substrate level for the etching process 430.

[0058]

[0065] In yet other embodiments, the oxidation step 420, as well as steps 405 and optional steps 410, 415 for generating oxygen-containing plasma wastewater, can be performed in a chamber separate from the chamber into which the halogenated precursor can be supplied in step 425 to initiate the etching step 430. Using two chambers maintained at different temperatures for the oxidation step 420 and the etching step 430 respectively may involve extra time for transporting the substrate from one chamber to the other. However, since temperature adjustment inside each chamber may not be required, the processing time can be saved, and since sufficient oxidation is ensured in one cycle, the overall processing time can be shortened.

[0059]

[0066] In some embodiments, depending on the thickness of the molybdenum-containing first liner formed on at least a portion of the sidewall of the trench, method 400 can be performed in cycles to facilitate complete oxidation and removal of molybdenum outside the lateral recess so that the molybdenum regions are reliably separated from each other. As shown in FIG. 4, method 400 can include repeating oxidation steps 405-420 and etching steps 425-430. As described above, depending on the processing conditions, due to the initial rapid oxidation of suitable or clean molybdenum, a molybdenum oxide layer having a thickness of about 10 Å to about 400 Å or more can be generated before the oxidation process slows down. To improve processing efficiency, after the initial rapid oxidation, the oxidation of molybdenum can be paused and the removal of the oxidized molybdenum can be initiated. After the removal of molybdenum, the flow of the oxygen-containing precursor can be resumed to start another cycle of method 400. In some embodiments, the oxidation and removal steps can be performed for 2 cycles or more, such as 3 cycles, 4 cycles, 5 cycles, or more, to achieve complete removal of the molybdenum-containing first liner formed on at least a portion of the sidewall of the trench.

[0060]

[0067] Referring to FIG. 6, which illustrates exemplary steps of another method 600 according to an embodiment of the present technology. The steps of method 600 are also schematically shown in FIGS. 7A - 7D, which illustrate a processed structure 700 similar to the processed structure 500 of FIGS. 5A - 5D. Method 600 may include steps 605 - 630 similar to steps 405 - 430 of method 400. In some embodiments, method 600 may include, at step 605, supplying an oxygen-containing precursor to a remote plasma region of a semiconductor processing chamber. The remote plasma region may be a remote plasma system (RPS) fluidly coupled to the processing region, or may include a capacitively coupled plasma (CCP) region as described above with reference to method 400. Method 600 may further include, at step 610, forming a plasma of the oxygen-containing precursor to generate oxygen-containing plasma wastewater, and at step 615, supplying the oxygen-containing plasma wastewater to the processing region. At step 620, the oxygen-containing plasma wastewater may contact and oxidize molybdenum connecting the molybdenum region 725 to form molybdenum oxide 755 inside and on top of the trench 705, as shown in FIG. 7B. The oxygen-containing precursor may include various fluids and may include one or more of atomic oxygen, molecular oxygen (O2), N2O, NO, NO2, CO2, ozone (O3), or any other oxygen-containing precursor capable of performing an oxidation process similarly.

[0061]

[0068] Although FIG. 6 illustrates oxidizing molybdenum using oxygen-containing plasma, method 600 may include supplying molecular oxygen (O2), ozone (O3), or other oxygen-containing precursors to the processing region instead of supplying plasma wastewater to oxidize molybdenum. In embodiments where molecular oxygen can be used to oxidize molybdenum, the temperature inside the processing chamber or at the substrate level may be maintained from about 250°C to about 600°C. In embodiments where ozone can be used to oxidize molybdenum, ozone may be generated using an ozone generator fluidly coupled to the inlet of the processing chamber.

[0062]

[0069] The residual plasma wastewater can be purged before step 625. In step 625, a halogenated precursor can be supplied to the processing region. The halogenated precursor can include a metal halide or other halogen-containing precursor that can interact with molybdenum oxide. The metal halide can include tungsten chloride such as tungsten pentachloride, and / or tungsten fluoride such as tungsten hexafluoride. In step 630, the halogenated precursor can modify molybdenum oxide 755, interact to form volatile substances, and then be removed from the chamber. The volatile substances formed from the halogenated precursor and molybdenum oxide 755 can include molybdenum oxychloride and / or molybdenum oxyfluoride.

[0063]

[0070] Method 600 may differ from method 400 in that the process conditions can be adjusted such that a gate metal barrier such as oxide or nitride barrier 745 cannot be oxidized, or at least cannot be fully oxidized, as shown in FIG. 7B. Thus, when the etching step 630 for etching molybdenum oxide 755 is completed, the oxide or nitride barrier 745 may not be etched and a portion thereof may be exposed as shown in FIG. 7C. The residual plasma wastewater can be purged before step 635. To remove the exposed portion of the oxide or nitride barrier 745, method 600 can include supplying a fluorine-containing precursor and an optional hydrogen-containing precursor to the remote plasma region of the processing chamber in step 635. Again, the remote plasma region can be a remote plasma system (RPS) fluidly coupled to the processing region, or can include a capacitively coupled plasma (CCP) region as described above. Method 600 can further include forming a plasma of the fluorine-containing precursor and the optional hydrogen-containing precursor to generate a fluorine-containing plasma wastewater and an optional hydrogen-containing plasma wastewater that can be supplied to the processing region in step 640 and step 645. The fluorine-containing plasma wastewater and the optional hydrogen-containing plasma wastewater can form a fluorinated portion of the oxide or nitride barrier 745.

[0064]

[0071] The fluorine-containing precursor may include at least one precursor selected from the group consisting of atomic fluorine, diatomic fluorine, nitrogen trifluoride, carbon tetrafluoride, hydrogen fluoride, xenon difluoride, and various other fluorine-containing precursors used in or useful for semiconductor processing. An exemplary fluorine-containing precursor used in method 600 may include nitrogen trifluoride. Other sources of fluorine can be used together with nitrogen trifluoride or as an alternative to nitrogen trifluoride. The hydrogen-containing precursor may include diatomic hydrogen, hydrocarbons, water, hydrogen peroxide, or other materials that may include hydrogen. The precursor may also include any number of carrier gases, including nitrogen, helium, argon, or other noble gases, inert gases, or useful precursors.

[0065]

[0072] The residual plasma wastewater can be purged before step 650. After forming the fluorinated portion of the oxide or nitride barrier 745, method 600 may include, in step 650, supplying a chlorine-containing precursor to the remote plasma region of the processing chamber. Method 600 may further include, in optional step 655, forming a plasma of the chlorine-containing precursor to generate chlorine-containing plasma wastewater that can be supplied to the processing region in step 660. In embodiments, since some chlorine-containing precursors can be used in thermal etching, method 600 may not include forming a plasma of the chlorine-containing precursor. The chlorine-containing precursor may include at least one precursor selected from the group consisting of atomic chlorine, diatomic chlorine, boron trichloride, and various other chlorine-containing precursors used in or useful for semiconductor processing. An exemplary chlorine-containing precursor used in method 600 may include boron trichloride. Other chlorine sources can be used in combination with boron trichloride or as an alternative to boron trichloride. The precursor may also include any number of carrier gases, including nitrogen, helium, argon, or other noble gases, inert gases, or useful precursors.

[0066]

[0073] In process 665, the plasma wastewater of the chlorine-containing precursor interacts with the fluorinated portion of the oxide or nitride barrier 745 to form volatile by-products, whereby, as shown in FIG. 7D, the fluorinated portion of the oxide or nitride barrier 745 can be removed. By process 665, the second liner over the molybdenum and / or molybdenum oxide can be selectively etched. The temperature and / or pressure of the processing chamber can be maintained similar to the temperature and / or pressure used in the oxidation process of molybdenum to facilitate the removal of the exposed portion of the oxide or nitride barrier 745. In other embodiments, the process temperature and / or pressure during the removal of the barrier material may be similar to the process temperature and / or pressure during the removal of molybdenum oxide.

[0067]

[0074] In an embodiment, any one of the fluorine-containing precursor, the hydrogen-containing precursor, or the chlorine-containing precursor can be supplied to an additional region of the processing chamber bypassing the remote plasma region. For example, the fluorine-containing precursor can be supplied through the remote plasma region to generate fluorine-containing plasma wastewater, while the hydrogen-containing precursor can bypass the remote plasma region. The hydrogen-containing precursor can bypass the remote plasma region by a bypass circuit at the top of the chamber or can be supplied into another region of the chamber through a port or the like that provides access to a region within the showerhead such as the showerhead 225 of FIG. 2A. The hydrogen-containing precursor is then supplied to the processing region where it is mixed or interacts with the fluorine-containing plasma wastewater.

[0068]

[0075] In some embodiments, depending on the thickness of the molybdenum-containing first liner formed on at least a portion of the sidewall of the trench and / or the thickness of the oxide or nitride barrier 745, the method 600 can be executed in cycles to promote complete oxidation and removal of the molybdenum and / or the oxide or nitride barrier 745 outside the lateral recesses to reliably separate the molybdenum regions from each other. As shown in FIG. 6, the method 600 may include repeating the oxidation steps 605-620 and the etching steps 625-630, similar to steps 665-635. Depending on the processing conditions, due to the initial rapid oxidation of suitable or clean molybdenum, a molybdenum oxide layer having a thickness of about 10 Å to about 400 Å or more may be generated before the oxidation process slows down. To improve the processing efficiency, after the initial rapid oxidation, the oxidation of molybdenum can be paused and the removal of the oxidized molybdenum can be started. After the removal of molybdenum, the flow of the oxygen-containing precursor can be resumed to start another cycle of the method 600. In some embodiments, to achieve complete removal of the molybdenum-containing first liner formed on at least a portion of the sidewall of the trench, two or more cycles of the oxidation and removal steps, such as 3 cycles, 4 cycles, 5 cycles, or more cycles, can be executed. The same may be true for the removal of the liner material.

[0069]

[0076] Following step 665, the molybdenum-containing metal region may be partially surrounded by the liner material, for example, three sides may be surrounded by the liner material. Further, the molybdenum-containing material within each recess may be separated from the molybdenum-containing materials within the remaining plurality of recesses.

[0070]

[0077] In the foregoing description, for the purpose of explanation, numerous details have been set forth in order to provide an understanding of various embodiments of the present technology. However, it will be apparent to those skilled in the art that some of these details may be omitted or additional details may be added to implement a particular embodiment.

[0071]

[0078] While several embodiments have been disclosed, those skilled in the art will recognize that various modifications, alternative structures, and equivalents can be used without departing from the gist of the embodiments. Further, to avoid unnecessarily obscuring the present technology, some well-known processes and elements have not been described. Accordingly, the above description should not be construed as limiting the scope of the present technology. Further, although a method or process may be described sequentially or stepwise, it should be understood that the steps may be performed simultaneously or in an order different from that recited.

[0072]

[0079] When a range of values is provided, it is to be understood that each intervening value, to the smallest unit of the lower limit's unit, between the upper and lower limits of that range is also specifically disclosed, unless the context clearly dictates otherwise. Any narrower range between any of the recited values or intervening values of the recited range and any other recited value or intervening value of that recited range is also included. The upper and lower limits of these smaller ranges may independently be included in or excluded from the range, and each range that includes one or both of the limiting values of the smaller range, or neither of the limiting values, is also included within the present technology, in accordance with any specifically excluded limiting value in the recited range. When one or both of the limiting values of the recited range are included, ranges excluding one or both of the included limiting values are also included.

[0073]

[0080] As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, a reference to "a precursor" includes a plurality of the above precursors, a reference to "a layer" includes a reference to one or more layers known to those skilled in the art and their equivalents, and the like.

[0074]

[0081] Also, as used in this specification and the following claims, the terms "comprise," "comprising," "contain," "containing," "include," and "including" are intended to specify the presence of the stated feature, integer, component, or step, but do not preclude the presence or addition of one or more other features, integers, components, steps, acts, or groups.

Claims

1. A semiconductor processing method, comprising: Supplying an oxygen-containing precursor to a semiconductor processing chamber, wherein a substrate is positioned in the semiconductor processing chamber, and the substrate includes: Trenches formed between columns; and A molybdenum-containing metal region in a plurality of recesses formed in at least one of the columns, wherein at least two of the molybdenum-containing metal regions are connected by a molybdenum-containing first liner formed on at least a part of a sidewall of the trench; Supplying the oxygen-containing precursor to the semiconductor processing chamber; Forming a plasma of the oxygen-containing precursor in the semiconductor processing chamber; Contacting the molybdenum-containing first liner with plasma wastewater of the oxygen-containing precursor, wherein a molybdenum oxide portion is formed on the molybdenum-containing first liner by the contact; Supplying a halogenated precursor to the semiconductor processing chamber; Contacting the molybdenum oxide portion with plasma wastewater of the halogenated precursor, wherein the molybdenum oxide portion is removed from the sidewall of the trench by the contact; And a method comprising the above steps.

2. The semiconductor processing method according to claim 1, wherein the oxygen-containing precursor includes ozone.

3. The semiconductor processing method according to claim 1, wherein the plasma of the oxygen-containing precursor is formed with a plasma output of about 2000 W or less.

4. The semiconductor processing method according to claim 1, wherein the molybdenum oxide portion has a thickness of about 100 Å or less.

5. The semiconductor processing method according to claim 1, wherein the halogenated precursor includes a fluorine-containing precursor.

6. The semiconductor processing method according to claim 5, wherein the fluorine-containing precursor includes tungsten hexafluoride.

7. By forming the oxidized portion of the molybdenum, a layer of molybdenum oxide formed along the sidewall of the trench is generated, and the thickness of the layer of molybdenum oxide close to the upper region of the trench is different from that of the layer of molybdenum oxide close to the lower region of the trench by about 30% or less. The semiconductor processing method according to claim 1.

8. The substrate further includes a second liner disposed adjacent to the molybdenum-containing metal region and the molybdenum-containing first liner, and the method further includes: supplying a fluorine-containing precursor to the semiconductor processing chamber; forming a plasma of the fluorine-containing precursor to generate fluorine-containing plasma waste water; contacting the second liner with the fluorine-containing plasma waste water to form a fluorinated portion of the second liner; supplying a chlorine-containing precursor to the semiconductor processing chamber; forming a plasma of the chlorine-containing precursor to generate chlorine-containing plasma waste water; contacting the fluorinated portion of the second liner with the chlorine-containing plasma waste water, wherein the fluorinated portion of the second liner is removed by the contact. Contacting the fluorinated portion of the second liner with the chlorine-containing plasma waste water The semiconductor processing method according to claim 1, including:

9. Contacting the molybdenum-containing first liner with the plasma waste water of the oxygen-containing precursor and contacting the oxidized portion of the molybdenum with the plasma waste water of the halogenated precursor are repeated at least twice. The semiconductor processing method according to claim 1.

10. A semiconductor processing method, i) forming a plasma wastewater of an oxygen-containing precursor; ii) contacting a molybdenum-containing first liner connecting at least two molybdenum-containing metal regions disposed in a plurality of recesses defined by at least one column of trenches with the plasma wastewater of the oxygen-containing precursor, wherein upon contact, an oxidized portion of molybdenum is formed on the molybdenum-containing first liner, contacting the molybdenum-containing first liner connecting at least two molybdenum-containing metal regions disposed in a plurality of recesses defined by at least one column of trenches with the plasma wastewater of the oxygen-containing precursor; iii) forming a plasma wastewater of a fluorine-containing precursor; iv) contacting the oxidized portion of molybdenum with the plasma wastewater of the fluorine-containing precursor, wherein upon contact, the oxidized portion of molybdenum is removed, contacting the oxidized portion of molybdenum with the plasma wastewater of the fluorine-containing precursor; A method comprising the above steps.

11. The semiconductor processing method according to claim 10, wherein steps i) to iv) are repeated at least twice.

12. The oxygen-containing precursor contains ozone, The fluorine-containing precursor contains tungsten hexafluoride, The semiconductor processing method according to claim 10.

13. The semiconductor processing method according to claim 10, wherein the temperature is maintained at about 200°C to about 600°C between steps i) and ii).

14. The semiconductor processing method according to claim 10, wherein the pressure is maintained at about 20 Torr or less between steps i) and ii).

15. Further comprising adjusting the temperature, pressure, or both before contacting the oxidized portion of molybdenum with the plasma wastewater of the fluorine-containing precursor. The semiconductor processing method according to claim 10.

16. further comprising a second liner disposed adjacent to the molybdenum-containing metal region and the molybdenum-containing first liner, the method further comprising forming a plasma of the fluorine-containing precursor to generate fluorine-containing plasma wastewater, the fluorine-containing precursor including nitrogen trifluoride, forming a plasma of the fluorine-containing precursor to generate fluorine-containing plasma wastewater; contacting the second liner with the fluorine-containing plasma wastewater to form a fluorinated portion of the second liner; forming a plasma of a chlorine-containing precursor to generate chlorine-containing plasma wastewater, the chlorine-containing precursor including boron trichloride, forming a plasma of the chlorine-containing precursor to generate chlorine-containing plasma wastewater; contacting the fluorinated portion of the second liner with the chlorine-containing plasma wastewater, such that the fluorinated portion of the second liner is removed by the contact, contacting the fluorinated portion of the second liner with the chlorine-containing plasma wastewater The semiconductor processing method according to claim 10, comprising

17. The semiconductor processing method according to claim 16, wherein the second liner includes an oxygen-containing material, a nitrogen-containing material, or an oxygen-nitrogen-containing material.

18. A semiconductor structure, comprising a substrate; a silicon-containing material covering the substrate, the substrate including trenches formed between columns, at least one column defining a plurality of recesses, the silicon-containing material; a liner extending into the plurality of recesses along the at least one column; A molybdenum-containing metal region formed in the plurality of recesses, the molybdenum-containing metal region being partially surrounded by the liner, and the thickness of the molybdenum-containing metal region in the recess close to the upper region of the trench being different from the molybdenum-containing metal region in the recess close to the lower region of the trench by about 30% or less, the molybdenum-containing metal region and A semiconductor structure comprising.

19. The semiconductor structure according to claim 18, wherein the trench has a depth of about 5 μm or more.

20. The molybdenum-containing metal region is surrounded by the liner on three sides, The molybdenum-containing metal region of one recess is separated from the molybdenum materials of the remaining plurality of recesses, The semiconductor structure according to claim 18.

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