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 on May 27, 2022, and the entire disclosure thereof is incorporated herein by reference.

[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 enabled by a process of forming complexly patterned material layers on a substrate surface. To form patterned materials on a substrate, a controlled method for removing exposed materials 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 a 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 be difficult to penetrate some restricted trenches and sometimes deform residual materials. Dry etching generated by a local plasma formed within a substrate processing region can penetrate more restricted trenches and cause less deformation of fragile residual structures. However, local plasma can damage the substrate because it generates an electrical arc during discharge.

[0005]

[0005] Therefore, 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 this technology. [Overview of the Initiative]

[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 in 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 the 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 wastewater of the oxygen-containing precursor. Contact may form an oxidized molybdenum portion on the molybdenum-containing first liner. The method may include supplying a halogenation precursor to the semiconductor processing chamber. The method may include contacting the oxidized molybdenum portion with the plasma wastewater of the halogenation precursor. Contact may remove the oxidized molybdenum portion from the sidewall of the trench.

[0007]

[0007] In some embodiments, the oxygen-containing precursor may be or may contain ozone. The plasma of the oxygen-containing precursor may be formed with a plasma output of about 2000 W or less. The molybdenum oxide portion may be characterized by having a thickness of about 100 Å or less. The halogenation precursor may be or may contain a fluorine-containing precursor. The fluorine-containing precursor may be or may contain tungsten hexafluoride. By forming the molybdenum oxide portion, a layer of molybdenum oxide formed along the sidewall of the trench may be generated. The thickness of the molybdenum oxide layer adjacent to the upper region of the trench may differ in thickness from the molybdenum oxide layer adjacent to the lower region of the trench by only about 30% or less. 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 a 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 a 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. The fluorinated portion of the second liner may be removed by contact. Contacting the molybdenum-containing first liner with plasma wastewater of an oxygen-containing precursor and contacting the oxidized portion of molybdenum with plasma wastewater of a halogenation precursor may be repeated at least twice.

[0008]

[0008] Several embodiments of the present technology encompass semiconductor processing methods. The method may include i) forming plasma wastewater of an oxygen-containing precursor. The method may include ii) contacting a molybdenum-containing first liner connecting at least two molybdenum-containing metal regions located in a plurality of recesses defined by at least one column of a trench with the plasma wastewater of the oxygen-containing precursor. Contact may form an oxidized molybdenum portion on the molybdenum-containing first liner. The method may include iii) forming plasma wastewater of a fluorine-containing precursor. The method may include iv) contacting the oxidized molybdenum portion with the plasma wastewater of the fluorine-containing precursor. Contact may remove the oxidized molybdenum portion.

[0009]

[0009] In some embodiments, steps i) to iv) may be repeated at least twice. The oxygen-containing precursor may be or may contain ozone. The fluorine-containing precursor may be or may contain tungsten hexafluoride. During steps i) and ii), the temperature may be maintained between about 200°C and about 600°C. During steps i) and ii), the pressure may be maintained below about 20 Torr. The method may include adjusting the temperature, pressure, or both before bringing the oxidized molybdenum portion into contact with the plasma wastewater of the fluorine-containing precursor. The second liner may be positioned 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 fluorine-containing plasma wastewater. The fluorine-containing precursor may be or may contain nitrogen trifluoride. The method may further include contacting the second liner with fluorine-containing plasma wastewater to form a fluorinated portion of the second liner, and forming a plasma of a chlorine-containing precursor to generate chlorine-containing plasma wastewater. The chlorine-containing precursor may be or may contain boron trichloride. The method may further include contacting the fluorinated portion of the second liner with chlorine-containing plasma wastewater. Contact may remove the fluorinated portion of the second liner. The second liner may be an oxygen-containing material, a nitrogen-containing material, or an oxygen-nitrogen-containing material, or may contain an oxygen-containing material, a nitrogen-containing material, or an oxygen-nitrogen-containing material.

[0010]

[0010] Some embodiments of the present technology encompass 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 along at least one column into a plurality of recesses. The structure may include molybdenum-containing metal regions formed within the plurality of recesses. The molybdenum-containing metal regions may be partially surrounded by the liner. The thickness of the molybdenum-containing metal region in a recess adjacent to the upper region of the trench may differ in thickness from that of the molybdenum-containing metal region in a recess adjacent to the lower region of the trench by only about 30% or less.

[0011]

[0011] In some embodiments, the trenches may be characterized by having 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 in one recess may be separated from the molybdenum material in the remaining multiple recesses.

[0012]

[0012] The above technology may offer numerous advantages over conventional systems and technologies. For example, this 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, along with their many advantages and features, in conjunction with the accompanying drawings.

[0013]

[0013] The nature and advantages of the disclosed technology can be further understood by referring to the remainder of the specification and the drawings. [Brief explanation of the drawing]

[0014] [Figure 1] This is a top view showing one embodiment of an exemplary processing system according to an embodiment of the present technology. [Figure 2A] This is a schematic cross-sectional view showing an exemplary processing chamber according to an embodiment of this technology. [Figure 2B] This is a detailed view showing a part of the processing chamber illustrated in Figure 2A according to an embodiment of this technology. [Figure 3] This is a bottom view showing an exemplary shower head according to an embodiment of this technology. [Figure 4] This figure shows an exemplary step in the method according to an embodiment of this technology. [Figure 5A-B] This is a cross-sectional view showing a substrate processed according to an embodiment of this technology. [Figure 5C-D] This is a cross-sectional view showing a substrate processed according to an embodiment of this technology. [Figure 6] This figure shows an exemplary step in the method according to an embodiment of this technology. [Figure 7A-B] This is a cross-sectional view showing a substrate processed according to an embodiment of this technology. [Figure 7C-D] This is a cross-sectional view showing a substrate processed according to an embodiment of this technology. [Modes for carrying out the invention]

[0015]

[0022] Some drawings are included as schematic diagrams. Please understand that the diagrams are for illustrative purposes only and should not be considered to scale unless the scale is specified. Furthermore, as schematic diagrams, they are provided to aid understanding and may not include all aspects or information compared to realistic representations, and may contain exaggerated materials for illustrative purposes.

[0016]

[0023] In the attached diagrams, similar components and / or features may be given the same reference label. Furthermore, various components of the same type may be distinguished by adding a letter after the reference label to distinguish similar components. If only the first reference label is used herein, its description is applicable to any one of the similar components having the same first reference label, regardless of the letter.

[0017]

[0024] The increasing demand for mobile computing and data centers continues to drive the need for high-capacity, high-performance NAND flash technology. As planar NAND approaches its practical scaling limits, 3D NAND is replacing 2D NAND for memory devices. Manufacturing 3D NAND structures requires the deposition of alternating layers of two or more materials. For example, some structures may use alternating layers of silicon oxide and silicon, or silicon oxide and silicon nitride, or silicon oxide and molybdenum, with a total stack thickness of up to a few microns, among other combinations. These stacks can be etched into trenches or contact holes. Furthermore, one or at least a portion of these two alternating materials can be selectively etched from the trenches to form memory cells. For example, in alternating layers of silicon oxide and silicon, silicon oxide and silicon nitride, or silicon oxide and molybdenum, the respective materials that need to be removed, at least partially, are silicon, silicon nitride, or molybdenum. When forming a laminate, if a liner material such as aluminum oxide, hafnium oxide, titanium nitride, tantalum nitride, or hafnium nitride is used between silicon oxide and molybdenum, it may be necessary to remove the liner as well.

[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, and sometimes extremely high. Due to the high aspect ratio of the trenches (more than 10:1), a common problem includes uniformly etching materials such as the above-mentioned molybdenum and liner materials from the top to the bottom within the feature. For such applications, the wet method has been conventionally 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 almost completely etch each layer to other memory holes, which makes it more difficult to place the cell layer at an appropriate or desired position, and the structure may be weakened and deformed. Further, as the size of the structure continues to shrink, problems of pattern collapse or adhesion 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. 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 technology 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 by 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 by 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 technology, 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. Thus, the 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 technology, it should be understood that the technology is applicable to virtually any semiconductor processing chamber that can enable the described process.

[0022]

[0029] Figure 1 is a top view showing one embodiment of a deposition, etching, firing, and curing chamber processing system 100 according to an embodiment. In the figure, a pair of forward-opening unified pods (FOUPs) 102 supply substrates of various sizes, which are received by a robotic 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. A second robotic arm 110 is used to transport the substrate wafers back and forth from the holding area 106 to the substrate processing chambers 108a-f. Each substrate processing chamber 108a-f may be equipped to perform a number of substrate processing steps, including periodic layer deposition (CLD), atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), etching, pre-cleaning, degassing, orientation, and other substrate processes, as well as the dry etching process described herein.

[0023]

[0030] The substrate processing chambers 108a-f may include one or more system components for depositing dielectric or metallic films on a substrate wafer, annealing, curing, and / or etching dielectric or metallic films on the substrate wafer. In one configuration, two pairs of processing chambers, e.g., 108c-d and 108e-f, may be used for depositing material on the substrate, and a third pair of processing chambers, e.g., 108a-b, may be used for etching the deposited material. In another configuration, all three pairs of chambers, e.g., 108a-f, may be configured to etch dielectric or metallic films on the substrate. Any one or more of the described processes may be carried out in a separate chamber(s) 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 system 100.

[0024]

[0031] Figure 2A is a cross-sectional view showing an exemplary process chamber system 200 having a plasma generation region partitioned within a processing chamber. For example, during film etching of titanium nitride, tantalum nitride, molybdenum, tungsten, copper, cobalt, silicon, polysilicon, silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, etc., a process gas may 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 may then process the first gas moving through the gas inlet assembly 205. The gas inlet assembly 205 may include two or more separate gas supply channels, and a second channel (not shown) may bypass the RPS 201 if one is included.

[0025]

[0032] A pedestal 265 is shown having a cooling plate 203, a faceplate 217, an ion suppressor 223, a shower head 225, and a substrate 255 disposed thereon, each of which may be included according to the embodiment. The pedestal 265 may have heat exchange channels through which a heat exchange fluid can flow to control the temperature of the substrate and which can operate to heat and / or cool the substrate or wafer during the processing steps. The wafer support platter of the pedestal 265, which may include aluminum, ceramic, or a combination thereof, may be resistance-heated using embedded resistance heating elements to achieve relatively high temperatures, such as from about 100°C or below to about 600°C or above.

[0026]

[0033] The faceplate 217 may be pyramidal, conical, or other similar structure with a narrow top that widens to a broad bottom. The faceplate 217 may also be flat as shown and include a number of through channels used for distributing process gases. Depending on the use of the RPS 201, plasma-generating gases and / or plasma-excited species may pass through a number of holes in the faceplate 217, as shown in Figure 2B, for more uniform delivery into the first plasma region 215.

[0027]

[0034] An exemplary configuration may include a gas inlet assembly 205 that opens into a gas supply region 258, which is partitioned by the faceplate 217 from the first plasma region 215, so that a gas / seed flows into the first plasma region 215 through a hole in the faceplate 217. Structural and operational features 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 the fluid supply system 210. The faceplate 217, or the conductive upper part of the chamber, and the showerhead 225 are illustrated together with an insulating ring 220 that is positioned between the features and allows an alternating potential to be applied to the faceplate 217 relative to the showerhead 225 and / or ion suppressor 223. The insulating ring 220 may be positioned between the faceplate 217 and the showerhead 225 and / or ion suppressor 223, allowing a capacitively coupled plasma (CCP) to form in the first plasma region. A baffle (not shown) may further be located in the first plasma region 215 or may be otherwise coupled to the gas inlet assembly 205, and may influence the fluid flow into the region through the gas inlet assembly 205.

[0028]

[0035] The ion suppressor 223 may include a plate or other geometric dimension defining multiple openings throughout the structure, configured to suppress the movement of charged ions out of the first plasma region 215 while allowing uncharged neutral or radical species 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 opening configurations. These uncharged species may include highly reactive species transported through the openings along with a less reactive carrier gas. As described above, the movement of ion species through the openings can be reduced, and in some cases completely suppressed. By controlling the amount of ion species passing through the ion suppressor 223, control over the mixed gas in contact with the underlying wafer substrate can be advantageously improved, resulting in improved control over the deposition and / or etching properties of the mixed gas. 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 altered. In alternative embodiments where deposition is performed, the balance between conformal deposition and fluid deposition of the dielectric material can also be shifted.

[0029]

[0036] Multiple openings in the ion suppressor 223 may be configured to control the passage of the activated gas, i.e., ionic species, radical species, and / or neutral species, through the ion suppressor 223. For example, the aspect ratio of the holes, or the diameter of the holes relative to the length of the holes, and / or the shape dimensions of the holes may be controlled to reduce the flow of charged ionic species in the activated gas passing through the ion suppressor 223. The holes in the ion suppressor 223 may include a tapered portion facing the plasma excitation region 215 and a cylindrical portion facing the showerhead 225. The cylindrical portion may be shaped and sized to control the flow of ionic species delivered to the showerhead 225. An adjustable electrical bias may 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 may function to reduce or remove the amount of charged ions moving from the plasma generation region to the substrate. Uncharged neutral and radical species can pass through the openings of the ion suppressor and react with the substrate. It should be noted that complete removal of charged ions in the reaction region surrounding the substrate may not be achieved in some embodiments. In some cases, ions are intended to reach the substrate to carry out etching and / or deposition processes. In such cases, the ion suppressor may help control the concentration of ions in the reaction region at a level that supports the process.

[0031]

[0038] By combining the showerhead 225 with the ion suppressor 223, it is possible to avoid the plasma present in the first plasma region 215 directly exciting the gas in the substrate processing region 233, while allowing 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 coming into contact with the substrate 255 being etched. This advantageously protects various complex structures and films patterned on the substrate that could be damaged, displaced, or otherwise distorted if the generated plasma comes into direct contact with them. Furthermore, bringing the plasma into contact with the substrate or bringing it close to the substrate level can increase the etching rate of oxide species. Therefore, if the exposed area of ​​the material is an oxide, this material can be further protected by keeping 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 power the faceplate 217, ion suppressor 223, showerhead 225, and / or pedestal 265 to generate plasma in the first plasma region 215 or 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 allow for the use of a tunable plasma in the process being performed. Unlike remote plasma units, which are often given an on or off function, a tunable 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 properties that can dissociate precursors in a particular way to improve the etching profile produced by these precursors.

[0033]

[0040] Plasma can be ignited in either the chamber plasma region 215 above the showerhead 225 or the substrate processing region 233 below the showerhead 225. Plasma may be present in the chamber plasma region 215 to generate radical precursors from the influx of fluorine-containing precursors or other precursors, for example. Typically, an AC voltage in the radio frequency (RF) range can be applied between the conductive upper part of the processing chamber, such as the faceplate 217, and the showerhead 225 and / or ion suppressor 223 to ignite the plasma in the chamber plasma region 215 during deposition. The RF power supply can 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 diagram 253 showing features that affect the distribution of the processing gas through the faceplate 217. As shown in Figures 2A and 2B, the faceplate 217, the cooling plate 203, and the gas inlet assembly 205 intersect to define a gas supply region 258 from which the processing gas can be delivered from the gas inlet assembly 205. The gas can fill the gas supply region 258 and flow through openings 259 in the faceplate 217 to the first plasma region 215. The openings 259 can be configured to guide the flow substantially in one direction, thereby allowing the process gas to flow into the substrate processing region 233, but partially or completely preventing it from flowing back into the gas supply region 258 after crossing the faceplate 217.

[0035]

[0042] A gas distribution assembly, such as a showerhead 225, for use in the processing chamber section 200 may be referred to as a dual-channel showerhead (DCSH), which is further detailed in the embodiment shown in Figure 3. The dual-channel showerhead can provide an etching process that can separate the etching solution outside the substrate processing area 233, thereby limiting the interaction between chamber components and each other before they are delivered into the processing area.

[0036]

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

[0037]

[0044] Figure 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 Figure 2A. The through-holes 365, illustrated as the first fluid channel 219, may have multiple shapes and configurations to control and influence the flow of precursor through the showerhead 225. The small holes 375, illustrated as the second fluid channel 221, may be substantially evenly distributed on the surface of the showerhead within the through-holes 365 and may help to obtain a more even mixing of precursor as it exits the showerhead than other configurations.

[0038]

[0045] The aforementioned chamber may be used to perform exemplary methods, including etching methods. Refer to Figure 4, which shows exemplary steps in Method 400 according to an embodiment of the present technology. Prior to the first step of Method 400, the substrate can be treated in one or more ways. For example, an interpolydielectric (IPD) layer can be formed on the substrate. The IPD layer may contain any number of materials and may contain alternating layers of placeholder material and dielectric material. In embodiments, the dielectric material may be silicon oxide or may contain silicon oxide, and the placeholder material may be silicon nitride or may contain silicon nitride. One or more trenches or memory holes may be formed through the stacked IPD layers, and the trenches may divide the IPD layers into columns for further processing into a 3D NAND structure. For example, a layer of placeholder material or at least a portion thereof can be removed to form a transverse recess along the sidewall of the column. The transverse recess can then be lined with a gate dielectric and filled with a gate metal to form the gate structure of the 3D NAND. In the embodiment, the gate dielectric may be aluminum oxide or contain aluminum oxide, and the gate metal may be molybdenum, tungsten, cobalt, or any other conductive material or contain 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 contain, a metal, metal oxide, or metal nitride such as hafnium, titanium, tantalum, aluminum oxide, hafnium oxide, hafnium nitride, titanium nitride, or tantalum nitride. Typically, the gate metal can be deposited from top to bottom within the trench and in lateral recesses formed along the sidewalls of the trench to form a metallic region interposed between the layers of dielectric material of the IPD layer. During deposition, the gate metal can also be deposited outside the lateral recesses to line a portion of the trench sidewalls and connect the metallic regions. Such lining or connecting metal can be removed to separate the metallic regions from each other, preventing crosstalk or short circuits between cells. Some or all of the process may be performed in a chamber or system tool that includes one or more chambers in which the steps of method 400 are performed to remove the connecting metal lining the trench sidewalls, as described above, or 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 in Figures 5A to 5D. Figure 5A illustrates a portion of the processed structure 500 that is further developed in the manufacturing of 3D NAND structures. The processed structure 500 may include one or more trenches 505 (only one is shown) formed between adjacent vertical columns 510 of a lamination covering a substrate 515. The lamination may include dielectric layers and metal layers or metal regions interposed between the dielectric layers to form the gate structure of each memory cell. The dielectric layers may include oxide layers such as a silicon oxide layer 520, as shown in Figure 5A. The metal regions may include molybdenum regions such as a molybdenum region 525, as shown in Figure 5A. The molybdenum region 525 may be formed by depositing molybdenum in a lateral recess 527 formed by removing a layer or part thereof of placeholder material. When forming the molybdenum region 525, molybdenum can also be deposited along the top 530, bottom 535, and side walls 540 of the trench 505, and two or more molybdenum regions 525 can be connected. The processed structure 500 may further include one or more barrier materials or liner materials, such as a gate metal barrier and a gate dielectric, which may be collectively or individually referred to as a second liner. The gate metal barrier may include an oxide, nitride, or oxygen-nitrogen barrier, such as an oxide or nitride barrier 545 (e.g., aluminum oxide, hafnium oxide, titanium nitride, tantalum nitride, hafnium nitride, etc.), as shown in Figure 5A. The oxide or nitride barrier, also referred to as a second liner, may be placed adjacent to the molybdenum-containing metal region and / or molybdenum-containing first liner. The gate dielectric may include an aluminum oxide gate dielectric, such as a gate dielectric 550 (e.g., aluminum oxide), as shown in Figure 5A. The oxide or nitride barrier 545 may be a metal-containing oxide or nitride material. The treated structure 500 is expected to include only one of the oxide or nitride barrier 545 and the gate dielectric 550.

[0041]

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

[0042]

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

[0043]

[0050] The oxygen-containing precursor may contain 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. The oxygen-containing precursor can be supplied at a rate of at least 1000 sccm, and in embodiments, 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 higher. In some embodiments, the flow of the oxygen-containing precursor may be pulsed. In this embodiment, the flow of the oxygen-containing precursor may be pulsed for a period of time of approximately 60 seconds or less, or it may be pulsed for a period of approximately 55 seconds or less, approximately 50 seconds or less, approximately 45 seconds or less, approximately 40 seconds or less, approximately 35 seconds or less, approximately 30 seconds or less, approximately 25 seconds or less, approximately 20 seconds or less, approximately 15 seconds or less, approximately 10 seconds or less, and approximately 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 is sufficient, or even 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, supplying sufficient oxygen can further improve the uniformity of the thickness of the molybdenum oxide layer formed inside the trench. This uniformity may be due in part to the initial rapid oxidation occurring on a suitable or clean molybdenum surface. Specifically, method 400 can be performed after the molybdenum has deposited inside the trench but before it is exposed to the atmosphere. The oxidation rate on a suitable molybdenum surface can be sufficiently rapid with sufficient oxygen supply so that the molybdenum near the bottom of the trench can be oxidized almost simultaneously to a thickness that may be substantially the same as the thickness of the oxidized molybdenum near the top of the trench. As the oxidation penetrates the metal surface, the oxidation rate may decrease dramatically, and in some embodiments, it may reach a saturation depth where only minimal oxidation can continue or no further oxidation can continue under chamber conditions. Therefore, despite the long residence time in locations close to the top of the trench, metals located at the bottom of the trench or other locations far from initial contact with the plasma wastewater can be oxidized to the same or substantially the same depth as those at the top of the trench.

[0045]

[0052] In some embodiments, initial rapid oxidation can produce molybdenum oxide layers having thicknesses of approximately 10 Å or more, approximately 15 Å or more, approximately 20 Å or more, approximately 25 Å or more, approximately 30 Å or more, approximately 35 Å or more, approximately 40 Å or more, approximately 50 Å or more, approximately 60 Å or more, approximately 70 Å or more, approximately 80 Å or more, approximately 90 Å or more, approximately 100 Å or more, or more, before the oxidation process slows down. In some embodiments, by adjusting the processing conditions, initial rapid oxidation can produce molybdenum oxide layers having thicknesses of approximately 100 Å or less, approximately 90 Å or less, approximately 80 Å or less, approximately 70 Å or less, approximately 60 Å or less, approximately 50 Å or less, approximately 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 Figure 5B, upper-to-bottom molybdenum oxide packing ratios 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 substantially or essentially 1:1 can be achieved using Method 400. Considering the initial rapid oxidation, the flow of the oxygen-containing precursor may 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 may 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 longer. Thus, in some embodiments, the flow of the oxygen-containing precursor may be maintained for a time of about 5 seconds to about 15 minutes, about 30 seconds to about 10 minutes, about 1 minute to about 5 minutes, or any other suitable time.

[0046]

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

[0047]

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

[0048]

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

[0049]

[0056] Figure 4 illustrates the oxidation of molybdenum and / or liner material using an oxygen-containing plasma, but non-plasma processes can also be used. Therefore, in some embodiments, steps 410 and 415 of Method 400 can be omitted. The molybdenum and / or liner material can be oxidized by supplying an oxygen-containing precursor, such as one or more of atomic oxygen, molecular oxygen (O2), ozone (O3), or other oxygen-containing precursors, to the processing area. In embodiments in which molecular oxygen is used to oxidize the molybdenum and / or liner material, the temperature in the processing chamber or at the substrate level can be maintained between about 250°C and about 600°C. The temperature can be maintained above about 250°C, and can be maintained above about 300°C, above about 350°C, above about 400°C, above about 450°C, above about 500°C, above about 550°C, above about 600°C, or higher. In embodiments in which ozone may be used for the oxidation of molybdenum and / or liner material, ozone may be generated using an ozone generator that can be fluidly coupled to the inlet of the processing chamber.

[0050]

[0057] In some embodiments, with a sufficient supply of oxygen-containing precursor and appropriate process conditions, substantially all of the molybdenum-containing first liner formed on the sidewalls of the trench 505 can be oxidized, and as shown in Figure 5C, a portion 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 a subsequent step of Method 400. As also shown in Figure 5C, if the oxide or nitride barrier 545 contains nitride during the oxidation step 420, the portion of the oxide or nitride barrier 545 in contact with the molybdenum oxide 555 may also be oxidized, forming an oxidized portion of the nitride barrier 560.

[0051]

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

[0052]

[0059] The etching rate of the oxidized portion of the liner material by the halogenation precursor may be at least about 2, 3, 4, 5, 6, 7, 8 times, or more than, the etching rate of the non-oxidized portion of the liner material by the halogenation precursor. The volatile substances formed from the halogenation precursor and the oxidized portion of the nitride barrier 560 may include metal chlorides such as metal oxychlorides, metal oxyfluorides, and metal tetrachlorides, and / or metal fluorides such as metal tetrafluorides. The halogenation precursor may be delivered during step 425 for a period of time from about 15 seconds to about 5 minutes. In embodiments, the delivery of the halogenation precursor may be continued 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, in order to ensure complete removal of the oxidized portion of molybdenum oxide 555 and / or the nitride barrier 560. As shown in Figure 5D, the oxidized portions of the molybdenum oxide 555 and / or nitride barrier 560 can be removed upon completion of the etching process 430, thereby separating the molybdenum regions 525 from each other.

[0053]

[0060] In etching step 430, the oxidized portions of 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 interposed between the molybdenum region 525 and the gate dielectric 550, and the gate dielectric 550. Although not bound by any particular theory, the gate dielectric 550 may not be etched by the halogenation precursor because the bond between oxygen and metal in the gate dielectric may be stronger than the bond between oxygen and molybdenum and / or between oxygen and metal in the gate dielectric, and in some cases, if reactive products are present, they may include metal fluorides and / or metal oxyfluorides that are substantially non-volatile under the process conditions of etching step 430. Although not explicitly shown in Figure 5D, method 400 can also selectively remove the oxidized portions of molybdenum oxide 555 and the nitride barrier 560 with respect to silicon oxide such as the silicon oxide layer 520, and silicon nitride that may form the charge trap layer of the memory cell.

[0054]

[0061] Since the halogenation precursor can selectively etch only the oxidized portions of the molybdenum oxide 555 and / or nitride barrier 560, and the oxidation step 420 can result in substantially uniform top-to-bottom filling as described above, the etching step 430 can also result in substantially uniform top-to-bottom filling. In embodiments, the etched thickness of the molybdenum layer adjacent to the upper region of the trench may differ from the etched thickness of the molybdenum layer adjacent to the lower region of the trench etched by method 400 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. Therefore, top-to-bottom filling ratios of molybdenum etching of approximately 1.3:1 or less, approximately 1.25:1 or less, approximately 1.2:1 or less, approximately 1.15:1 or less, approximately 1.1:1 or less, approximately 1.05:1 or less, or substantially or essentially 1:1 can be achieved using Method 400. Such uniform top-to-bottom filling can prevent or limit over-etching of the molybdenum regions 525 inside the lateral recesses 527 of the trench 505, and facilitate the complete removal of any molybdenum that may accumulate on the sidewalls 540 and / or bottom 535 of the trench 505, thereby ensuring that the molybdenum regions 525 are separated from each other.

[0055]

[0062] Furthermore, by using a halogenation precursor as the etching solution, the isotropic etching it can provide can further improve filling from top to bottom. Compared to conventional reactive ion etching, which can impart directionality and make it difficult to laterally etch the oxidized portions of the molybdenum oxide 555 and / or nitride barrier 560 lining the sidewalls 540 of the trench 505, the halogenation precursor can react substantially uniformly with the oxidized portions of the molybdenum oxide 555 and / or nitride barrier 560 inside the trench 505, resulting in substantially isotropic etching of the oxidized portions of the molybdenum oxide 555 and / or nitride barrier 560 inside the trench 505. Such uniformity can be promoted by maintaining the pressure in the processing chamber at or above approximately 10 Torr, 15 Torr, 20 Torr, 25 Torr, 30 Torr, 35 Torr, 40 Torr, 45 Torr, 50 Torr, 55 Torr, 60 Torr, 70 Torr, 80 Torr, 90 Torr, 100 Torr, or higher. By increasing the pressure in the processing chamber, the mean free path of the halogenation precursor can be reduced, achieving non-directional flow of the halogenation precursor and thereby achieving isotropic etching in the trench. Alternatively, in some embodiments, during the etching step 430, the pressure in the processing chamber may be maintained at or below approximately 100 Torr, approximately 90 Torr, approximately 80 Torr, approximately 70 Torr, approximately 60 Torr, approximately 55 Torr, approximately 50 Torr, approximately 45 Torr, approximately 40 Torr, approximately 35 Torr, approximately 30 Torr, approximately 25 Torr, approximately 20 Torr, approximately 15 Torr, approximately 10 Torr, approximately 5 Torr, approximately 1 Torr, or less. Thus, in some embodiments, method 400 may further include adjusting the process conditions in the processing chamber (e.g., temperature, pressure, or both) between the oxidation step and the etching step. For example, in some embodiments, the pressure may be adjusted during oxidation from approximately 5 Torr or less to approximately 10 Torr or more.Either of the aforementioned pressures or ranges can be used similarly during the two processes.

[0056]

[0063] As described above, a relatively high temperature may be maintained in the processing chamber or at the substrate level during the oxidation step 420 of method 400 to promote uniform oxidation. In some embodiments, a relatively low temperature may be maintained in the processing chamber or at the substrate level during the etching step 430. Due to the high volatility of by-products formed using the halogenation precursor, high temperatures may not be required to achieve effective etching. Furthermore, relatively low temperatures can also limit or prevent the surface migration of non-volatile or low-volatility by-products that may be formed, such as aluminum fluoride, as described above. During the etching step 430, the temperature in the processing chamber or at the substrate level may be maintained between approximately 250°C and approximately 400°C. In some embodiments, the temperature may be maintained below approximately 400°C, and in some embodiments, it may be maintained below approximately 350°C, below approximately 300°C, below approximately 250°C, or below. In some embodiments, a relatively high temperature may be maintained in the processing chamber or at the substrate level during the etching step 430 to increase the reaction rate. In some embodiments, the temperature maintained in the processing chamber or at the substrate level during the etching step 430 may be the same as, or higher than, the temperature maintained in the processing chamber or at the substrate level during the oxidation step 420. Therefore, during the etching step 430, the temperature in the processing chamber or at the substrate level may be maintained at or above approximately 400°C, approximately 450°C, approximately 500°C, approximately 550°C, approximately 600°C, or higher.

[0057]

[0064] There may be several ways to maintain different temperatures within the processing chamber or at the substrate level during the oxidation process 420 and the etching process 430. 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 the flow of the halogenation precursor is started in process 425. Alternatively or additionally, in some embodiments, during the oxidation process 420, the substrate can be positioned near a heating 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 heating source to lower the temperature at the substrate level for the etching process 430. For example, in some embodiments, the showerhead 225 may include a heater or be configured to be heated. During the oxidation process, the substrate may be positioned close to the showerhead to raise the substrate and process temperatures, and the substrate may be positioned at a first distance from the heating source. Following the oxidation process, the substrate may be moved parallel to a second distance from the showerhead and heating source, for example by lowering the height of the pedestal, in order to reduce the heating effect. Next, as the substrate is moved, the etching process may be performed at a second temperature lower than the first temperature. In some embodiments in which the etching process 430 may be performed at a higher temperature than the oxidation process 420, the substrate can be positioned further away from the heating source inside the processing chamber to achieve a relatively low temperature at the substrate level during the oxidation process 420, and then, following the oxidation process 420, the substrate can be moved closer to the heating source to raise the temperature at the substrate level for the etching process 430.

[0058]

[0065] In yet another embodiment, the oxidation step 420, as well as steps 405 and optional steps 410, 415 for generating oxygen-containing plasma wastewater, may be performed in a separate chamber from the chamber in which the halogenation precursor may 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 may involve extra time for transporting the substrate from one chamber to the other. However, processing time can be saved because temperature control inside each chamber may not be necessary, and the overall processing time can be reduced because sufficient oxidation is ensured in one cycle.

[0059]

[0066] In some embodiments, depending on the thickness of the molybdenum-containing first liner formed on at least a portion of the trench sidewalls, Method 400 may be performed in cycles to facilitate complete oxidation and removal of molybdenum outside the lateral recesses, ensuring that the molybdenum regions are separated from each other. As shown in Figure 4, Method 400 may include repeating oxidation steps 405-420 and etching steps 425-430. As described above, depending on the processing conditions, the initial rapid oxidation of suitable or clean molybdenum may generate a molybdenum oxide layer having a thickness of about 10 Å to about 400 Å or more before the oxidation process slows down. To improve processing efficiency, the oxidation of molybdenum can be paused after the initial rapid oxidation to initiate the removal of oxidized molybdenum. After the removal of molybdenum, the flow of the oxygen-containing precursor can be restarted to initiate another cycle of Method 400. In some embodiments, the oxidation and removal process can be performed for two or more cycles, such as three, four, five, or more, to achieve complete removal of the molybdenum-containing first liner formed on at least a portion of the trench sidewalls.

[0060]

[0067] Refer to Figure 6, which shows exemplary steps of another method 600 according to an embodiment of the present technology. The steps of method 600 are also schematically shown in Figures 7A to 7D, which show a processed structure 700 similar to the processed structure 500 in Figures 5A to 5D. Method 600 may include steps 605 to 630 similar to steps 405 to 430 of method 400. In some embodiments, method 600 may include, in 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 forming a plasma of the oxygen-containing precursor to generate oxygen-containing plasma wastewater in step 610, and supplying the oxygen-containing plasma wastewater to the processing region in step 615. In step 620, the oxygen-containing plasma wastewater may come into contact with and oxidize the molybdenum connecting the molybdenum region 725 in order to form molybdenum oxide 755 inside and above the trench 705, as shown in Figure 7B. The oxygen-containing precursor may contain a variety of 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 the oxidation process.

[0061]

[0068] Figure 6 illustrates the oxidation of molybdenum using an oxygen-containing plasma, but method 600 may include supplying molecular oxygen (O2), ozone (O3), or other oxygen-containing precursors to the processing area instead of supplying plasma wastewater to oxidize molybdenum. In embodiments in which molecular oxygen can be used to oxidize molybdenum, the temperature inside the processing chamber or at the substrate level can be maintained between approximately 250°C and approximately 600°C. In embodiments in which ozone can be used to oxidize molybdenum, the ozone can be generated using an ozone generator that can be fluidically coupled to the inlet of the processing chamber.

[0062]

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

[0063]

[0070] Method 600 may differ from Method 400 in that the process conditions can be adjusted so that the gate metal barrier, such as the oxide or nitride barrier 745, cannot be oxidized, or at least not completely oxidized, as shown in Figure 7B. Therefore, when the etching step 630 for etching the molybdenum oxide 755 is completed, the oxide or nitride barrier 745 may not be etched and a portion of it may be exposed, as shown in Figure 7C. Residual plasma wastewater may be purged before step 635. To remove the exposed portion of the oxide or nitride barrier 745, Method 600 may include, in step 635, supplying a fluorine-containing precursor and an optional hydrogen-containing precursor to a remote plasma region of the processing chamber. Here again, 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. Method 600 may further include, in step 640, forming plasmas of a fluorine-containing precursor and an optional hydrogen-containing precursor to generate fluorine-containing plasma wastewater and optional hydrogen-containing plasma wastewater that can be supplied to the processing area in step 645. The plasma wastewater of the fluorine-containing precursor and the plasma wastewater of the optional hydrogen-containing precursor may form the 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 of atomic fluorine, diatomic fluorine, nitrogen trifluoride, carbon tetrafluoride, hydrogen fluoride, xenon difluoride, and various other fluorine-containing precursors used or useful in semiconductor processing. An exemplary fluorine-containing precursor used in Method 600 may include nitrogen trifluoride. Other sources of fluorine may be used together with nitrogen trifluoride or as a substitute for nitrogen trifluoride. The hydrogen-containing precursor may include diatomic hydrogen, hydrocarbons, water, hydrogen peroxide, or other materials that may contain hydrogen. The precursor may also include any number of carrier gases, which may include nitrogen, helium, argon, or other noble gases, inert gases, or useful precursors.

[0065]

[0072] Residual plasma wastewater may 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 a remote plasma region of the processing chamber. Method 600 may further include, in an optional step 655, forming a plasma of the chlorine-containing precursor to generate chlorine-containing plasma wastewater that may be supplied to the processing region in step 660. In embodiments, since several chlorine-containing precursors may 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 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 may be used in combination with or as substitutes for boron trichloride. The precursor may also include nitrogen, helium, argon, or other noble gases, inert gases, or useful precursors, and may include any number of carrier gases.

[0066]

[0073] In step 665, the plasma wastewater of the chlorine-containing precursor interacts with the fluorinated portion of the oxide or nitride barrier 745 to form volatile byproducts, thereby allowing the fluorinated portion of the oxide or nitride barrier 745 to be removed, as shown in Figure 7D. Step 665 allows the second liner over molybdenum and / or molybdenum oxide to be selectively etched. The temperature and / or pressure of the processing chamber may be maintained at the same temperature and / or pressure as used in the molybdenum oxidation step 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 the same as the process temperature and / or pressure during the removal of molybdenum oxide.

[0067]

[0074] In the embodiment, one of the fluorine-containing precursor, hydrogen-containing precursor, or chlorine-containing precursor may be supplied to an additional area of ​​the processing chamber by bypassing the remote plasma region. For example, the fluorine-containing precursor may be supplied through the remote plasma region to generate fluorine-containing plasma wastewater, while the hydrogen-containing precursor may bypass the remote plasma region. The hydrogen-containing precursor may bypass the remote plasma region by a bypass at the top of the chamber, or it may be supplied to another area of ​​the chamber via a port that provides access to an area within a showerhead, such as the showerhead 225 in Figure 2A. The hydrogen-containing precursor is then supplied to the processing area, where it mixes 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 trench sidewalls and / or the thickness of the oxide or nitride barrier 745, Method 600 may be run in cycles to facilitate the complete oxidation and removal of the molybdenum and / or oxide or nitride barrier 745 outside the lateral recesses to ensure that the molybdenum regions are separated from each other. As shown in Figure 6, Method 600 may include repeating the oxidation steps 605-620 and the etching steps 625-630, as well as steps 665-635. Depending on the processing conditions, initial rapid oxidation of suitable or clean molybdenum may generate a molybdenum oxide layer having a thickness of about 10 Å to about 400 Å or more before the oxidation process slows down. To improve processing efficiency, the oxidation of molybdenum can be paused after the initial rapid oxidation and the removal of the oxidized molybdenum can be initiated. After the removal of molybdenum, the flow of the oxygen-containing precursor can be restarted to initiate another cycle of Method 600. In some embodiments, two or more cycles of the oxidation and removal process, for example, three, four, five, or more cycles, may be performed to achieve complete removal of the molybdenum-containing first liner formed on at least a portion of the trench sidewalls. The same may apply to the removal of the liner material.

[0069]

[0076] Following step 665, the molybdenum-containing metal region may be partially surrounded by a liner material, for example, by the liner material on three sides. Furthermore, the molybdenum-containing material in each recess may be separated from the molybdenum-containing material in the remaining multiple recesses.

[0070]

[0077] In the specifications described so far, numerous details have been included for explanatory purposes to enable an understanding of the various embodiments of this technology. However, it will be clear to those skilled in the art that certain embodiments can be implemented by omitting some of these details or by adding additional details.

[0071]

[0078] While several embodiments have been disclosed, it will be recognized by those skilled in the art that various modifications, alternative structures, and equivalents can be used without departing from the spirit of the embodiments. Furthermore, to avoid unnecessarily obscuring the Art, some well-known processes and elements have not been described. Therefore, the above details should not be construed as limiting the scope of the Art. Moreover, while methods or processes may be described sequentially or stepwise, it should be understood that steps may be performed simultaneously or in an order different from that listed.

[0072]

[0079] Where a range of values ​​is provided, unless the context explicitly indicates otherwise, each intervening value between the upper and lower limits of that range, down to the smallest unit of the lower limit, is also specifically disclosed. This includes any narrower range between any unlisted intervening value of any listed value or range and any other listed value or intervening value of that range. The upper and lower limits of these smaller ranges may be independently included in or excluded from the range, and each range that includes one or both limits, or neither, is also included in this technology according to any specifically excluded limits in the listed range. Where a listed range includes one or both limits, ranges that exclude one or both of those included limits are also included.

[0073]

[0080] As used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context explicitly indicates otherwise. Thus, for example, a reference to "precursor" includes multiple such precursors, and a reference to "layer" includes one or more layers and their equivalents known to those skilled in the art, and so on.

[0074]

[0081] Furthermore, as used herein and in the following claims, the terms “comprise,” “comprising,” “contain,” “containing,” “include,” and “including” specify the presence of the described feature, integer, component, or process, but do not preclude the presence or addition of one or more other features, integers, components, processes, operations, or groups.

Claims

1. A semiconductor processing method, The process involves supplying an oxygen-containing precursor to a semiconductor processing chamber, wherein the substrate is positioned within the semiconductor processing chamber, and the substrate is Trench formed between columns, 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 in at least a portion of the side wall of the trench, and The oxygen-containing precursor, including the above, is supplied to the semiconductor processing chamber. Forming the plasma of the oxygen-containing precursor in the semiconductor processing chamber, The first molybdenum-containing liner is brought into contact with the plasma product of the oxygen-containing precursor, wherein, by contact, an oxidized molybdenum portion is formed on the first molybdenum-containing liner, and the first molybdenum-containing liner is brought into contact with the plasma product of the oxygen-containing precursor. The halogenation precursor is supplied to the semiconductor processing chamber, The oxidized portion of molybdenum is brought into contact with the plasma product of the halogenation precursor, wherein the oxidized portion of molybdenum is removed from the side wall of the trench by contact, and the oxidized portion of molybdenum is brought into contact with the plasma product of the halogenation precursor. Includes, A method wherein the steps of contacting the molybdenum-containing first liner with the plasma product of the oxygen-containing precursor and contacting the oxidized portion of the molybdenum with the plasma product of the halogenation precursor are repeated at least twice.

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 2000 W or less.

4. The semiconductor processing method according to claim 1, characterized in that the oxidized portion of the molybdenum has a thickness of 100 Å or less.

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

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

7. The semiconductor processing method according to claim 1, wherein by forming the oxidized portion of molybdenum, a layer of molybdenum oxide is generated along the side wall of the trench, and the thickness of the molybdenum oxide layer adjacent to the upper region of the trench differs from that of the molybdenum oxide layer adjacent to the lower region of the trench by only 30% or less.

8. The substrate further includes the molybdenum-containing metal region and a second liner disposed adjacent to the molybdenum-containing first liner, and the method further includes The fluorine-containing precursor is supplied to the semiconductor processing chamber, To generate a fluorine-containing plasma product, a plasma of the fluorine-containing precursor is formed, To form the fluorinated portion of the second liner, the second liner is brought into contact with the fluorine-containing plasma product, The chlorine-containing precursor is supplied to the semiconductor processing chamber, To generate chlorine-containing plasma products, a plasma of the chlorine-containing precursor is formed, The fluorinated portion of the second liner is brought into contact with the chlorine-containing plasma product, and the fluorinated portion of the second liner is removed by contact. The semiconductor processing method according to claim 1, including the following:

9. A semiconductor processing method, i) Formation of plasma products of oxygen-containing precursors, ii) Contacting a molybdenum-containing first liner connecting at least two molybdenum-containing metal regions located in a plurality of recesses defined by at least one column of a trench with the plasma product of the oxygen-containing precursor, wherein, upon contact, an oxidized molybdenum portion is formed on the molybdenum-containing first liner, iii) Forming plasma products of fluorine-containing precursors, iv) Contacting the oxidized portion of molybdenum with the plasma product of the fluorine-containing precursor, wherein the oxidized portion of molybdenum is removed by contact; Includes, A method in which steps i) through iv) are repeated at least twice.

10. The oxygen-containing precursor contains ozone, The fluorine-containing precursor comprises tungsten hexafluoride. The semiconductor processing method according to claim 9.

11. The semiconductor processing method according to claim 9, wherein the temperature is maintained between 200°C and 600°C during steps i) and ii).

12. The semiconductor processing method according to claim 9, wherein the pressure is maintained at 20 Torr or less during steps i) and ii).

13. Before bringing the oxidized portion of the molybdenum into contact with the plasma product of the fluorine-containing precursor, adjust the temperature, pressure, or both. The semiconductor processing method according to claim 9, further comprising:

14. The method further comprises a molybdenum-containing metal region and a second liner disposed adjacent to the molybdenum-containing first liner, and the method further comprises To generate a fluorine-containing plasma product, a plasma of the fluorine-containing precursor is formed, wherein the fluorine-containing precursor contains nitrogen trifluoride. To form the fluorinated portion of the second liner, the second liner is brought into contact with the fluorine-containing plasma product, To produce a chlorine-containing plasma product, a plasma of a chlorine-containing precursor is formed, wherein the chlorine-containing precursor contains boron trichloride. The fluorinated portion of the second liner is brought into contact with the chlorine-containing plasma product, and the fluorinated portion of the second liner is removed by contact. The semiconductor processing method according to claim 9, including the method described in claim 9.

15. The semiconductor processing method according to claim 14, wherein the second liner comprises an oxygen-containing material, a nitrogen-containing material, or an oxygen-nitrogen-containing material.

16. It is a semiconductor structure, circuit board and A silicon-containing material covering the substrate, wherein the substrate includes trenches formed between columns, and at least one column defines a plurality of recesses, A liner extending along at least one column into the plurality of recesses, Molybdenum-containing metal regions formed within the plurality of recesses, wherein the molybdenum-containing metal region is covered by the liner on three surfaces: an upper surface, a lower surface, and a side opposite to the trench, and the molybdenum-containing metal region in one recess is separated from the molybdenum material in the remaining plurality of recesses, and the thickness of the molybdenum-containing metal region in a recess adjacent to the upper region of the trench differs from the thickness of the molybdenum-containing metal region in a recess adjacent to the lower region of the trench by only 30% or less. A semiconductor structure comprising the features described above.

17. The semiconductor structure according to claim 16, characterized in that the trench has a depth of 5 μm or more.

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