Systems and methods for selective metal compound removal

Abstract

An exemplary etching method can include flowing a fluorine-containing precursor and a hydrogen-containing precursor into a remote plasma region of a semiconductor processing chamber. The hydrogen-containing precursor can be flowed at a flow rate that is at least 2: 1 relative to a flow rate of the fluorine-containing precursor. The method can include forming a plasma of the fluorine-containing precursor and the hydrogen-containing precursor to generate a plasma effluent. The method can include flowing the plasma effluent into a substrate processing region that houses a substrate. The substrate can include an exposed region of a tantalum or titanium material and an exposed region of a silicon-containing material or a metal. The method can include contacting the substrate with the plasma effluent. The method can include selectively removing the tantalum or titanium material relative to the silicon-containing material or the metal.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit and priority of U.S. Nonprovisional Application No. 17 / 018,206, filed September 11, 2020, entitled “SYSTEMS AND METHODS FOR SELECTIVEMETAL COMPOUND REMOVAL,” which is incorporated herein by reference in its entirety. Technical Field

[0003] This technology relates to semiconductor processes and equipment. More specifically, this technology relates to the selective etching of metallic structures relative to other materials. Background Technology

[0004] Integrated circuits can be fabricated by processes that create complex patterned material layers on a substrate surface. Creating patterned material on the substrate requires a controlled method for removing exposed material. Chemical etching is used for various purposes, including transferring patterns from photoresist to underlying layers, thinning layers, or thinning the lateral dimensions of features already present on a surface. Often, an etching process is desired that etches one material faster than another, facilitating, for example, pattern transfer processes. Such etching processes are considered selective for the first material. Due to the diversity of materials, circuits, and processes, etching processes selective for multiple materials have been developed.

[0005] Depending on the materials used in the process, etching processes can be referred to as wet or dry processes. For example, wet etching can preferentially remove some oxide dielectrics relative to other dielectrics and materials. However, wet processes may struggle to penetrate some constrained trenches and can sometimes deform the remaining material. Dry etching, generated in localized plasmas formed in the substrate processing area, can penetrate more constrained trenches and exhibit less deformation of the fine remaining structure. However, localized plasmas can damage the substrate by generating arcs during their discharge.

[0006] Therefore, there is a need for improved systems and methods capable of producing high-quality devices and structures. This technology meets these and other needs. Summary of the Invention

[0007] An exemplary etching method can include flowing a fluorine-containing precursor and a hydrogen-containing precursor into a remote plasma region of a semiconductor processing chamber. The hydrogen-containing precursor can be flowed at a flow rate that is at least 2: 1 relative to a flow rate of the fluorine-containing precursor. The method can include forming a plasma of the fluorine-containing precursor and the hydrogen-containing precursor to generate a plasma effluent. The method can include flowing the plasma effluent into a substrate processing region that houses a substrate. The substrate can include an exposed region of a tantalum or titanium material and an exposed region of a silicon-containing material or a metal. The method can include contacting the substrate with the plasma effluent. The method can include selectively removing the tantalum or titanium material relative to the silicon-containing material or the metal.

[0008] In some embodiments, the tantalum or titanium material can be or include a tantalum or titanium metal or an oxide or nitride of tantalum or titanium. The metal can be tungsten, cobalt, or copper. The plasma power can be maintained at less than or about 1,000 W. The etching method can be performed at a temperature that is greater than or about 150 °C. The etching method can be performed at a pressure that is less than or about 10 Torr. The method can include performing a pre-treatment prior to flowing the fluorine-containing precursor. The pre-treatment can include contacting the substrate with a plasma that includes one or more of oxygen, hydrogen, water vapor, or nitrogen. The method can include performing a post-treatment after the etching method, where the post-treatment includes contacting the substrate with a plasma that includes one or more of hydrogen, nitrogen, oxygen, or water vapor. The method can include removing the substrate from the semiconductor processing chamber. The method can include removing residue from a chamber wall of the semiconductor processing chamber. Removing the residue can include providing a chlorine-containing precursor or plasma effluent, or a bromine-containing precursor or plasma effluent.

[0009] Some embodiments of the present technology can include an etching method. The method can include forming a plasma of a processing precursor that includes one or more of oxygen, hydrogen, or nitrogen to generate a processing plasma effluent. The method can include flowing the processing plasma effluent into a substrate processing region of a semiconductor processing chamber. The method can include contacting a substrate housed in the substrate processing region with the processing plasma effluent. The substrate can define an exposed region of a tantalum or titanium material and an exposed region of tungsten, cobalt, or copper. The method can include removing a carbon-containing material from a surface of the tantalum or titanium material. The method can include forming a plasma of a fluorine-containing precursor and a hydrogen-containing precursor. The method can include contacting the substrate with the plasma effluent. The method can include removing the tantalum or titanium material.

[0010] In some embodiments, the hydrogen-containing precursor can be flowed at a rate greater than or about 2: 1 relative to the fluorine-containing precursor. The plasma power during the formation of the fluorine-containing precursor plasma can be maintained at less than or about 1,000 W. The etching method can be performed at a temperature greater than or about 300 °C. The etching method can be performed at a pressure less than or about 10 Torr. The method can include performing a post-treatment after the etching method. The post-treatment can include contacting the substrate with a plasma comprising hydrogen. The method can include removing the substrate from the semiconductor processing chamber. The method can include removing residue from a chamber wall of the semiconductor processing chamber.

[0011] Some embodiments of the technology can include an etching method. The method can include flowing a fluorine-containing precursor and a hydrogen-containing precursor into a remote plasma region of a semiconductor processing chamber. The hydrogen-containing precursor can be flowed at a flow rate at least 2: 1 relative to a flow rate of the fluorine-containing precursor. The method can include forming a plasma of the fluorine-containing precursor and the hydrogen-containing precursor to produce a plasma effluent. The method can include flowing the plasma effluent into a substrate processing region housing a substrate. The substrate can include an exposed region of a tantalum or titanium material and an exposed region of a silicon-containing material or a metal. The method can include contacting the substrate with the plasma effluent. The method can include selectively removing the tantalum or titanium material relative to the silicon-containing material or the metal. The method can include forming a plasma of a treatment precursor comprising hydrogen to produce a treatment plasma effluent. The method can include contacting the substrate with the treatment plasma effluent.

[0012] In some embodiments, the treatment plasma effluent can be configured to remove residual fluorine from one or more of the substrate or the semiconductor processing chamber. The method can include removing the substrate from the semiconductor processing chamber. The method can include removing residue from a chamber wall of the semiconductor processing chamber with a chlorine-containing precursor.

[0013] The technology can provide many benefits over conventional systems and techniques. For example, the processes can allow for performing a dry etch that can protect features of the substrate. Additionally, the processes can selectively remove tantalum and titanium materials relative to other exposed materials on the substrate. These and other embodiments, along with many of their advantages, are described in more detail in conjunction with the following description and attached figures. BRIEF DESCRIPTION OF DRAWINGS

[0014] The nature and advantages of the disclosed technology can be understood better with reference to the remaining portions of the specification and the attached drawings.

[0015] Figure 1 A top plan view of an embodiment of an exemplary processing system according to some embodiments of the technology is shown.

[0016] Figure 2A A schematic cross-sectional view of an exemplary processing chamber according to some embodiments of the technology is shown.

[0017] Figure 2B A detailed view of a portion of the processing chamber is shown. Figure 2A A detailed view of a portion of the processing chamber is shown.

[0018] Figure 3 A bottom plan view of an exemplary showerhead is shown, in accordance with some embodiments of the present technology.

[0019] Figure 4 An exemplary operation of a method, in accordance with some embodiments of the present technology, is shown.

[0020] Figures 5A-5B A cross-sectional view of a processed substrate is shown, in accordance with embodiments of the present technology.

[0021] Several of the figures in the drawing are schematic. It should thus be appreciated that the figures are not necessarily drawn to scale. Furthermore, the figures are provided as illustrative, and there can be additional or fewer items than shown in the figures. As such, the figures can not include all of the aspects or information for a particular application, and the figures can be implemented to include fewer but more selective aspects or information.

[0022] In the drawings, like reference numerals can be used to denote similar components throughout the several views. Additionally, individual components of the same type can be distinguished from one another by a letter added to the reference numeral. If only the first reference numeral is used in the specification, the description is applicable to any one of the similar components having the same first reference numeral, regardless of the letter. DETAILED DESCRIPTION

[0023] Many different semiconductor processes can use dilute acids for cleaning substrates and removing materials from those substrates. For example, dilute hydrofluoric acid can be an effective etchant of silicon oxide, titanium oxide, and other materials, and can be used to remove these materials from a substrate surface. After an etching or cleaning operation is complete, the acid can be dried from the wafer or substrate surface. Using dilute hydrofluoric acid ("DHF") can be referred to as a "wet" etch, and the diluent is often water. Other etching processes can be used that use a precursor delivered to the substrate. For example, a plasma enhanced process can also perform a dry etch (including a reactive ion etch) by etching materials selectively through a plasma enhanced precursor.

[0024] While wet etchants using aqueous solutions or water-based processes can effectively operate for certain substrate structures, water can pose challenges under a variety of conditions. For example, using water during an etching process can cause problems when disposed on substrates including metallic materials. For example, after a certain amount of metallization has been formed on a substrate, certain post-fabrication processes or other processes such as recess gap, removal of oxide dielectric, or other processes can be performed to remove oxygen-containing materials. If water is used in some manner during etching, an electrolyte can be created that, when in contact with metallic materials, can cause galvanic corrosion between different metals and can corrode or displace metals in various processes. Additionally, due to the surface tension of the water diluent, minute structures can experience pattern distortion and collapse. Water-based materials also cannot penetrate some high aspect ratio features due to surface tension effects and etch rates in small spaces are reduced due to the electric double layer of the ion solution that can form, which can slow transport within the feature. This can extend exposure times and affect etching relative to other materials.

[0025] Plasma etching can resolve the problems associated with water-based etching, but other problems can arise. For example, reactive ion etching processes can expose metals to ion activity that can damage structures via impact, affecting electrical properties. The present technology performs dry etching processes that can limit collisions to surfaces while performing reactions that can facilitate removal of target materials, which resolves these problems. Additionally, the materials and conditions used can improve etching compared to conventional techniques.

[0026] While the remaining disclosure will routinely illustrate specific etching processes using the disclosed technology, it will be readily understood that the systems and methods are equally applicable to deposition and cleaning processes that can occur in the described chambers, as well as other etching techniques including mid- and back-end-of-line processing, as well as other etching that can be performed with a variety of exposed materials that can be maintained or substantially maintained. Thus, the present technology should not be considered limited to only using the exemplary etching processes or chambers. Furthermore, while exemplary chambers are described as providing the basis for the present technology, it should be understood that the present technology can be applied to nearly any semiconductor processing chamber that can allow the described operations to proceed.

[0027] Figure 1This diagram illustrates a top plan view of one embodiment of a processing system 100 having deposition, etching, baking, and curing chambers according to an embodiment. In the diagram, a pair of front-opening standard upholstery units (FOUPs) 102 provide substrates of various sizes, which are received by a robotic arm 104 and placed in a low-pressure holding region 106, and then placed in one of substrate processing chambers 108a to 108f, which are arranged in serial segments 109a to 109c. A second robotic arm 110 is used to transport substrate wafers from the holding region 106 to the substrate processing chambers 108a to 108f and back. Each substrate processing chamber 108a to 108f can be configured to perform multiple substrate processing operations, including the dry etching processes described herein, as well as 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.

[0028] The substrate processing chambers 108a to 108f may include one or more system components for depositing, annealing, curing, and / or etching dielectric films on a substrate wafer. In one configuration, two pairs of processing chambers (e.g., 108c to 108d and 108e to 108f) may be used to deposit dielectric material on the substrate, and a third pair of processing chambers (e.g., 108a to 108b) may be used to etch the deposited dielectric. In another configuration, all three pairs of chambers (e.g., 108a to 108f) may be configured to etch dielectric films on the substrate. Any or more of the described processes may be performed in chambers separate from the manufacturing systems shown in the different embodiments. It will be understood that system 100 encompasses other configurations of chambers for the deposition, etching, annealing, and curing of dielectric films.

[0029] Figure 2A A cross-sectional view of an exemplary processing system 200 is shown, showing a processing chamber with partitioned plasma generation regions. During film etching, process gases, such as titanium nitride, tantalum nitride, tungsten, silicon, polysilicon, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, etc., can flow through a gas inlet assembly 205 into a first plasma region 215. The system may optionally include a remote plasma system (RPS) 201, which can process the first gas, which then travels through the gas inlet assembly 205. The inlet assembly 205 may include two or more distinct gas supply channels, wherein a second channel (not shown) may bypass the RPS 201 (if present).

[0030] The cooling plate 203, faceplate 217, ion suppressor 223, showerhead 225, and susceptor 265 or substrate support on which a substrate 255 is disposed are illustrated, and each of the above components can include according to embodiments. The susceptor 265 can have heat exchange channels through which a heat exchange fluid flows to control the temperature of the substrate, which can be operated to heat and / or cool the substrate or wafer during processing operations. The wafer support disk of the susceptor 265, which can include aluminum, ceramic, or combinations thereof, can also be resistively heated using an embedded resistive heater assembly to achieve relatively high temperatures, for example, from up to or about 100 °C to greater than or about 1100 °C.

[0031] The faceplate 217 can be a pyramid, cone, or another similar structure, extending from a narrow top to a wide bottom. The faceplate 217 can additionally be flat as illustrated, including a plurality of through passages for distributing process gas. Depending on the use of the RPS 201, plasma generating gas and / or plasma excited species can be delivered through a plurality of holes in the faceplate 217, as shown, to more uniformly into the first plasma region 215. Figure 2B

[0032] The exemplary configuration can include the gas inlet assembly 205 opening into a gas supply region 258, which is separated from the first plasma region 215 by the faceplate 217, such that gas / species flow through the holes in the faceplate 217 into the first plasma region 215. The structural and operational features can be selected to prevent significant backflow of plasma from the first plasma region 215 into the supply region 258, gas inlet assembly 205, and fluid supply system 210. The conductive top of the faceplate 217 or chamber and the showerhead 225 are shown with an insulating ring 220 between these features, which applies an AC potential to the faceplate 217 relative to the showerhead 225 and / or ion suppressor 223. The insulating ring 220 can be positioned between the faceplate 217 and the showerhead 225 and / or ion suppressor 223 to form a capacitively coupled plasma (CCP) in the first plasma region. A baffle (not shown) can additionally be positioned in the first plasma region 215, or otherwise coupled with the gas inlet assembly 205, to influence the flow of fluid into the region via the gas inlet assembly 205.

[0033] ​The ion suppressor 223 can include a plate or other geometry that defines a plurality of apertures through the structure that are configured to suppress the migration of ionically charged species out of the first plasma region 215 while allowing the passage of uncharged, neutral or radical species through the ion suppressor 223 into the activation gas delivery region between the suppressor and the showerhead. In embodiments, the ion suppressor 223 can include a multi-aperture plate having a plurality of aperture configurations. These uncharged species can include highly reactive species that are delivered with a low reactivity carrier gas through the apertures. As noted above, the migration of ion species through the apertures can be reduced, in some cases, the migration of ion species through the apertures can be completely suppressed. Controlling the amount of ion species that pass through the ion suppressor 223 can advantageously provide increased control over the gas mixture that contacts the underlying wafer substrate, which in turn can provide increased control over the deposition and / or etch characteristics of the gas mixture. For example, adjusting the ion concentration of the gas mixture can significantly alter its etch selectivity, such as SiNx:SiOx etch ratio, Si:SiOx etch ratio, etc. In alternative embodiments where deposition is performed, the balance of conformal and flowable deposition of dielectric materials can also be adjusted.

[0034] The plurality of apertures in the ion suppressor 223 can be configured to control the passage of activated gases, i.e., ions, radicals and / or neutral species, through the ion suppressor 223. For example, the aspect ratio of the apertures or the ratio of aperture diameter to length and / or the geometry of the apertures can be controlled such that the flow of ionically charged species of the activated gases through the ion suppressor 223 is reduced. The apertures in the ion suppressor 223 can include a conical portion facing the plasma excitation region 215 and a cylindrical portion facing the showerhead 225. The shape and size of the cylindrical portion can be adjusted to control the flow of ion species to the showerhead 225. An adjustable electrical bias can also be applied to the ion suppressor 223 as an additional means to control the flow of ion species through the suppressor.

[0035] The ion suppressor 223 can be used to reduce or eliminate the amount of ionically charged species that travel from the plasma generation region to the substrate. Uncharged, neutral and radical species can still pass through the openings in the ion suppressor to react with the substrate. It should be noted that in embodiments a complete elimination of ionically charged species in the reaction region around the substrate can not be performed. In some cases, it is expected that ion species reach the substrate to perform an etch and / or deposition process. In these cases, the ion suppressor can help control the ion species concentration in the reaction region to a level that is conducive to the process.

[0036] The showerhead 225 and ion suppressor 223 in combination can allow the plasma present in the first plasma region 215 to avoid directly exciting the gas in the substrate processing region 233 while still allowing excited species to travel from the chamber plasma region 215 into the substrate processing region 233. In this manner, the chamber can be configured to prevent plasma from contacting a substrate 255 that is being etched. This can advantageously protect a plurality of complex structures and films that are patterned on the substrate from damage, dislocation, or otherwise warping if directly contacted by the resulting plasma. Additionally, the rate of oxide species etching can increase when plasma is allowed to contact or approach the level of the substrate. Thus, if the exposed region of material is an oxide, this material can be further protected by maintaining the plasma remote from the substrate.

[0037] The processing system can further include a power source 240 electrically coupled to the processing chamber that provides power to the faceplate 217, ion suppressor 223, showerhead 225, and / or pedestal 265 to generate plasma in the first plasma region 215 or processing region 233. The power source can be configured to deliver adjustable amounts of power to the chamber depending on the process being performed. This configuration can allow for the use of adjustable plasma in the processes being performed. Unlike remote plasma units that often have an on or off function, adjustable plasma can be configured to deliver a specific amount of power to the plasma region 215. This in turn can allow for the development of specific plasma characteristics such that precursors are dissociated in a specific manner to enhance the etch profile generated by these precursors.

[0038] Plasma can be ignited in the chamber plasma region 215 above the showerhead 225 or in the substrate processing region 233 below the showerhead 225. Plasma can be present in the chamber plasma region 215 to generate radical precursors from the flow-in of, for example, fluorine containing precursors or other precursors. An AC voltage, typically in the radio frequency (RF) range, can be applied between the conductive top of the processing chamber, such as the faceplate 217, and the showerhead 225 and / or ion suppressor 223 to ignite plasma in the chamber plasma region 215 during deposition. The RF power source can generate a high RF frequency of 13.56 Mhz, but other frequencies can also be generated independently or in combination with the 13.56 MHz frequency.

[0039] Figure 2B A detailed view 253 of features that affect the distribution of process gas through the faceplate 217 is shown. As Figure 2A and Figure 2BAs shown, the faceplate 217, the cooling plate 203, and the gas inlet assembly 205 intersect to define a gas supply region 258 into which process gas can be delivered from the gas inlet 205. The gas can fill the gas supply region 258 and flow through orifices 259 in the faceplate 217 to the first plasma region 215. The orifices 259 can be configured to direct flow in a substantially unidirectional manner such that process gas can flow into the processing region 233, but upon crossing the faceplate 217, the process gas can be partially or completely prevented from flowing back into the gas supply region 258.

[0040] The gas distribution assembly (e.g., showerhead 225) used in the processing system 200 can be referred to as a dual channel showerhead (DCSH), and Figure 3 The described embodiments describe this in detail. The dual channel showerhead can provide an etching process that allows for separation of etchant outside of the processing region 233 to provide limited interaction with chamber components and each other prior to delivering the etchant into the processing region.

[0041] The showerhead 225 can include an upper plate 214 and a lower plate 216. These plates can be coupled to each other to define a volume 218 between the plates. The coupling of the plates can thereby provide a first fluid passage 219 through the upper and lower plates and a second fluid passage 221 through the lower plate 216. The resulting passages can be configured to allow fluid to enter from the volume 218 through the lower plate 216 only via the second fluid passage 221, and the first fluid passage 219 can be fluidically isolated from the volume 218 between the plates and the second fluid passage 221. Fluidic access to the volume 218 can be through one side of the showerhead 225.

[0042] Figure 3 is a bottom view of a showerhead 325 for use with a processing chamber according to embodiments. The showerhead 325 can correspond to Figure 2A The showerhead 225 as shown. The through-holes 365 show a view of the first fluid passage 219, which can have a number of shapes and configurations to control and affect the flow of precursor through the showerhead 225. The small holes 375 show a view of the second fluid passage 221, which can be substantially evenly distributed over the surface of the showerhead, even in the through-holes 365, and which can help to more evenly mix the precursor as it exits the showerhead as compared to other configurations.

[0043] Exemplary methods including etching methods can be performed using the chambers discussed previously. Reference is made to Figure 4which illustrates exemplary operations in a method 400 according to embodiments of the technology. The method 400 includes one or more operations prior to the start of the method, including front-end processing, deposition, gate formation, etching, polishing, cleaning, or any other operations that can be performed prior to the described operations. The method can include a number of optional operations that can or can not be specifically related to some embodiments of the method according to the technology. For example, a number of operations are described to provide a broader range of the performed processes, but this is not critical to the technology, or these operations can be performed by alternative methods that will be readily understood by those skilled in the art. The method 400 can describe Figures 5A-5B The operations shown are illustrative, and these figures will be described in connection with the operations of the method 400. It should be understood that the figures are only partially illustrative, and the substrate can include any number of other materials and features having the various properties and aspects illustrated in the figures.

[0044] The method 400 can or can not involve optional operations to develop the semiconductor structure to a particular manufacturing operation. It should be understood that the method 400 can be performed on any number of semiconductor structures, including exemplary structures, on which a metal material removal operation can be performed. As Figure 5A As shown in the exemplary structure 500 shown, the exemplary semiconductor structure can include a trench, via, or other recessed feature that can include one or more exposed materials. The structure can include a substrate 505 on which one or more materials can be located. For example, the exemplary substrate 505 can contain silicon or some other semiconductor substrate material and an interlayer dielectric material through which a recess, trench, via, or isolation structure can be formed, and the substrate 505 can also include one or more overlying materials. The exposed material can be or include a metal material, such as a gate, dielectric material, contact material, transistor material, or any other material that can be used in a semiconductor process. In some embodiments, the exemplary substrate can include a metal 510 through which a trench can be formed in an overlying material 515. The metal 510 can be or include tungsten, cobalt, copper, or some other material or metal within the substrate. The overlying material 515 can be or include a dielectric material (including an interlayer dielectric), which can be or include a silicon-containing material, such as silicon oxide, silicon oxycarbide, silicon oxycarbinitride, and silicon carbonitride. In some embodiments, the material can be silicon oxide, which can be characterized by a dielectric constant greater than or about 3.0 or up to or about 4.0, which can increase the selectivity of an etching process with respect to silicon oxide. Additionally, a titanium or tantalum material 520 can be included on the overlying material 515, and these materials can be the target material for removal. For example, the material can be titanium oxide, titanium nitride, tantalum oxide, tantalum nitride, or any other material that can include titanium or tantalum. The tantalum and / or titanium material can be exposed with respect to one or more other materials, including the metal 510 and the overlying material 515 or any of a number of other semiconductor materials with respect to which the tantalum and / or titanium material is to be removed.

[0045] It should be understood that the structures noted are not intended to be limiting, and similarly any of a variety of other semiconductor structures (including tantalum and / or titanium materials) are included. Other exemplary structures can include two-dimensional and three-dimensional structures common in semiconductor production, and within or on which a titanium-containing material and / or a tantalum-containing material is removed relative to one or more other materials, as the present technology can selectively remove tantalum or titanium materials relative to any number of other materials, including each of the materials noted above. Additionally, while high aspect ratio structures can benefit from the present technology, the present technology can be equivalently applied to low aspect ratio and any other structures.

[0046] For example, a feature of a structure layer according to the present technology can be in any aspect ratio or height to width ratio of the structure, but in some embodiments, the material can be characterized by a greater aspect ratio that can not allow for sufficient etching using conventional techniques or methods. For example, in some embodiments, the aspect ratio of any layer of an exemplary structure can be greater than or about 10: 1, greater than or about 20: 1, greater than or about 30: 1, greater than or about 40: 1, greater than or about 50: 1 or greater. Additionally, a feature of each layer can be in a smaller width or thickness, less than or about 100 nm, less than or about 80 nm, less than or about 60 nm, less than or about 50 nm, less than or about 40 nm, less than or about 30 nm, less than or about 20 nm, less than or about 10 nm, less than or about 50 nm, less than or about 1 nm or less, including any fraction of any of the noted numbers, such as 20.5 nm, 1.5 nm, etc. This combination of high aspect ratio and minimum thickness can be challenging for many conventional etching operations, or require very long etching times to remove the layer along a vertical or horizontal distance through the limited width. Moreover, conventional techniques can also damage or remove other exposed layers.

[0047] The method 400 can be performed in embodiments to remove exposed tantalum- or titanium-containing materials, but in embodiments of the present technology, any number of materials can be removed in any number of structures. The method can include specific operations for removing titanium and tantalum materials, and can include one or more optional operations for preparing or treating the materials to be etched or maintained. For example, an exemplary substrate structure can have prior processing residues on the film to be removed, such as titanium or tantalum materials. For example, residual photoresist or byproducts of a prior processing can be left on a titanium or tantalum layer. These materials can prevent access to the material to be removed, or can interact differently with an etchant than a clean surface, which can impede one or more aspects of the etching. Thus, in some embodiments, a pre-treatment of the titanium or tantalum material film or material can be optionally performed in operation 405. Exemplary pre-treatment operations can include a thermal treatment, a wet treatment, or a plasma treatment, such as can be performed in any number of chambers that can be included on the chamber 200 and the system 100 described above.

[0048] In an exemplary plasma process, a remote or local plasma can be generated from a precursor that is desired to interact with residue in one or more ways. For example, using a chamber such as chamber 200 described above, a remote or local plasma can be generated from one or more precursors. For example, an oxygen-containing precursor, a hydrogen-containing precursor, a nitrogen-containing precursor, a helium-containing precursor, and / or some other precursor can be flowed into a remote plasma region or a processing region where plasma can be struck. Plasma effluents can flow to a substrate and can contact residual material, such as carbon material or other mask or resist material residue. Depending on the material that is to be removed to expose a titanium or tantalum material, the plasma process can be a physical process or a chemical process. For example, the plasma effluents can flow to contact and physically remove residue (e.g., by a sputtering operation), or the precursors can flow to interact with the residue to generate volatile byproducts, which can be removed from the chamber.

[0049] Exemplary precursors used in the pretreatment can be or include hydrogen, a hydrocarbon, water vapor, an alcohol, hydrogen peroxide, or any material including hydrogen that would be understood by one skilled in the art. Exemplary oxygen-containing precursors can include molecular oxygen, ozone, dinitrogen monoxide, nitric oxide, or other oxygen-containing materials. Nitrogen gas can also be used, or a combination precursor having one or more of hydrogen, oxygen, and / or nitrogen can be used to remove particular residue. In some embodiments, the precursors can not include diatomic oxygen, which is more likely to oxidize the exposed metal. Once the residue or byproducts are removed, a clean titanium or tantalum surface can be exposed for etching.

[0050] Method 400 can include flowing a fluorine-containing precursor and a hydrogen-containing precursor into a remote plasma region of a semiconductor processing chamber in operation 410. The remote plasma region can be fluidically coupled to a processing region, but the remote plasma region can be physically separated from the processing region to confine the plasma at a substrate level, which can damage exposed structures or materials on structure 500. In some embodiments, the remote plasma region can include a remote plasma system (“RPS”) unit fluidically coupled to an inlet of the semiconductor processing chamber, such as RPS 201 discussed above. In some embodiments, the remote plasma region can include a capacitively coupled plasma (“CCP”) region, such as first plasma region 215 formed by capacitively coupled faceplate 217 and showerhead 225 and / or ion suppressor 223, and the CCP region can be physically separated from the processing region by one of its electrodes, such as showerhead 225 and / or ion suppressor 223. Method 400 can further include forming a plasma of the fluorine-containing precursor and the hydrogen-containing precursor to generate plasma effluents, and flowing the plasma effluents into the processing region to contact a substrate in operation 415. In operation 420, as Figure 5BAs shown, the titanium or tantalum material 520 can be removed from the substrate. In embodiments, the titanium or tantalum material can be selectively removed relative to the substrate, the metal 510, and the overlying material 515.

[0051] By using specific process conditions, the plasma removal can be performed as a selectively enhanced dry etch. Thus, techniques according to aspects of the present technology can be performed to remove tantalum and titanium materials from narrow features and high aspect ratio features, as well as thin dimensions that can not otherwise be suitable for wet etching or can damage other exposed materials. Optional operations can be performed to clean the substrate or chamber of residues, and post processing can be included in optional operation 425. The post processing can include similar operations as the pre processing, and can include any of the precursors or operations discussed above with respect to pre processing. In some embodiments, the post processing can clean residual fluorine from the substrate or chamber, and can include a hydrogen plasma.

[0052] In some embodiments, in optional operation 430, additional post processing can be performed to further remove residual titanium or tantalum material from the processing chamber, such as from the chamber walls or chamber components. For example, once the previous operations are complete, in some embodiments the substrate can be removed from the processing chamber. With the substrate removed, a plasma can be generated from a chlorine containing precursor that can be formed remotely, which can interact with residual titanium or tantalum fluoride material. As one non limiting example, boron trichloride can be used, which can dissociate to produce a variety of volatile materials. Continuing this example, for a titanium etch process, the effluent material can include titanium tetrafluoride, which is not intended to limit the present technology and it is understood that the same can occur for tantalum. During the process, a portion of this material can deposit on the chamber sidewalls. By forming a chlorine containing plasma, two volatile byproducts can be produced that are more volatile than the tetrafluoride. For example, chlorine can be transferred to the titanium or tantalum while boron accepts fluorine. Titanium tetrafluoride and boron trifluoride can be more volatile products, and both can be exhausted from the chamber. Additionally, at sufficient processing temperatures, including any of the temperatures discussed above, the process can be performed without a colliding plasma, and instead the process can include flowing a processing precursor into a processing region where a thermal reaction can be performed.

[0053] The fluorine containing precursor can 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 can include nitrogen trifluoride (NF3). Other sources of fluorine can be used with or in place of nitrogen trifluoride. The hydrogen containing precursor can include hydrogen, a hydrocarbon, water, hydrogen peroxide, or other materials that include hydrogen, although in some embodiments the precursors used for the etching operation can be oxygen free. The precursors can also include any number of carrier gases, which can include nitrogen, helium, argon, or other noble, inert, or effective precursors.

[0054] As a non-limiting example, while nitrogen trifluoride can readily dissociate in a plasma and etch a variety of materials including any of the exposed materials, in some embodiments by incorporating a hydrogen-containing precursor, the etching mechanism can be adjusted under process conditions. For example, in some embodiments, titanium or tantalum materials can be oxides or nitrides of titanium or tantalum, which can be etched with nitrogen trifluoride. For example, fluorine can interact with titanium or tantalum and produce volatile titanium or tantalum byproducts, and the residual nitrogen or oxygen can be exhausted. Similar processes can occur in many processes for silicon-containing materials or the metals noted above. However, the present technology can inhibit etching of these materials by incorporating a hydrogen-containing precursor.

[0055] Without being bound to any particular theory, when the plasma effluent includes an increased concentration of hydrogen, the interaction of hydrogen with silicon and metal materials can exceed the interaction with titanium or tantalum materials, and can terminate at the surface of these materials. For example, hydrogen can bond with silicon nitride, as one non-limiting example, and can form a hydrogen-saturated film. Similarly, any of the previously noted metals, such as tungsten, can have surface bond termination when exposed to an effective amount of hydrogen radicals. This effect can limit or prevent fluorine from penetrating the material structure, limiting or preventing etching of the material, which does not occur with titanium or tantalum materials, which do not have the same interaction with excess hydrogen.

[0056] In other words, in some embodiments, hydrogen can inhibit silicon and metal etching while maintaining titanium and / or tantalum etching. This can subsequently increase the selectivity of etching titanium or tantalum materials over any other exposed materials. Thus, in some embodiments, the flow rate ratio of hydrogen precursor to fluorine precursor can be maintained at greater than or about 1.0: 1, greater than or about 1.5: 1, greater than or about 2.0: 1, greater than or about 2.5: 1, greater than or about 3.0: 1, greater than or about 3.5: 1, greater than or about 4.0: 1, greater than or about 4.5: 1, greater than or about 5.0: 1, greater than or about 10: 1, or higher.

[0057] Processing conditions can influence and facilitate etching according to the present technology. For example, in some embodiments, an etch plasma can be generated at a lower plasma power, which can reduce fluorine dissociation and control the etch rate. In some embodiments, a plasma can be generated at a plasma power less than or about 1,000 W, and can be generated at a power less than or about 900 W, less than or about 800 W, less than or about 700 W, less than or about 600 W, less than or about 500 W, less than or about 400 W, less than or about 300 W, less than or about 200 W, or lower. Additionally, as the processing temperature is higher than or about 200 °C, the etch rate of titanium or tantalum material relative to passivated material can increase, which can represent dissociation of the precursor and / or reaction of the activated with the titanium or tantalum material. As the temperature continues to increase, dissociation can be further facilitated, as can reaction with the titanium or tantalum material.

[0058] Accordingly, in some embodiments of the present technology, an etching method can be performed at a substrate, pedestal, and / or chamber temperature higher than or about 150 °C, and can be performed at a temperature higher than or about 250 °C, higher than or about 250 °C, higher than or about 300 °C, higher than or about 350 °C, higher than or about 400 °C, higher than or about 450 °C, higher than or about 500 °C, or higher. The temperature can also be maintained at these ranges, smaller ranges contained therein, or any temperature within the range between any of these ranges. In some embodiments, the method can be performed on a substrate having a plurality of features generated, which can generate a thermal budget. Accordingly, in some embodiments, the method can be performed at a temperature lower than or about 800 °C, and can be performed at a temperature lower than or about 750 °C, lower than or about 700 °C, lower than or about 650 °C, lower than or about 600 °C, lower than or about 550 °C, lower than or about 500 °C, or lower.

[0059] The temperature within the chamber can also affect the operations performed, as well as the temperature at which the halogen dissociates from the transition metal. Thus, in some embodiments, the pressure can be maintained below about 50 Torr, below or about 40 Torr, below or about 30 Torr, below or about 25 Torr, below or about 20 Torr, below or about 15 Torr, below or about 10 Torr, below or about 9 Torr, below or about 8 Torr, below or about 7 Torr, below or about 6 Torr, below or about 5 Torr, below or about 4 Torr, below or about 3 Torr, below or about 2 Torr, below or about 1 Torr, below or about 0.1 Torr or lower. The pressure can also be maintained at any pressure within these ranges, smaller ranges contained in these ranges, or between any of these ranges. In some embodiments, the processing pressure can be maintained between about 1 Torr and about 10 Torr, which can facilitate the initiation of etching, and can facilitate etching of titanium or tantalum materials. Additionally, as the pressure continues to increase, the etching can rise to a point, then begin to decrease, and eventually stop as the pressure continues to increase, can inhibit interaction with titanium or tantalum materials as the pressure continues to increase, or can reintroduce byproduct fluorine to the etched film, further limiting removal. Thus, in some embodiments, the pressure within the processing chamber can be maintained below or about 10 Torr in some embodiments.

[0060] Further control over the etching process can be added, in some embodiments the fluorine-containing precursor can be pulsed, and the fluorine-containing precursor can be delivered continuously or in a series of pulses in the etching process, which can be constant or vary over time. Pulsed delivery can be characterized by a first time period of fluorine-containing precursor flow, and a second time period of fluorine-containing precursor pause or stop. The time periods of any pulsed operation can be the same as or different from each other, either time period can be longer. In embodiments, the time period or continuous flow of precursor can be for a time period greater than or about 1 second, greater than or about 2 seconds, greater than or about 3 seconds, greater than or about 4 seconds, greater than or about 5 seconds, greater than or about 6 seconds, greater than or about 7 seconds, greater than or about 8 seconds, greater than or about 9 seconds, greater than or about 10 seconds, greater than or about 11 seconds, greater than or about 12 seconds, greater than or about 13 seconds, greater than or about 14 seconds, greater than or about 15 seconds, greater than or about 20 seconds, greater than or about 30 seconds, greater than or about 45 seconds, greater than or about 60 seconds or longer. The time can also be any smaller range contained in any of these ranges. In some embodiments, the etch rate can increase when the precursor is delivered for a longer time period.

[0061] By performing operations according to embodiments of the present technology, titanium-containing materials or tantalum-containing materials can be selectively etched relative to other materials including any of the materials previously described. For example, the present technology can selectively etch titanium or tantalum materials relative to exposed regions of metals including tungsten, cobalt, or copper or dielectrics including the previously mentioned silicon-containing materials. Embodiments of the present technology can etch titanium-containing materials and / or tantalum-containing materials at a rate of at least about 20: 1 relative to any of the metals or silicon-containing materials, and can etch titanium or tantalum materials at a selectivity of greater than or about 25: 1, greater than or about 30: 1, greater than or about 50: 1, greater than or about 100: 1, greater than or about 150: 1, greater than or about 200: 1, greater than or about 250: 1, greater than or about 300: 1, greater than or about 350: 1, greater than or about 400: 1, greater than or about 450: 1, greater than or about 500: 1, or higher relative to the other exposed materials noted. For example, etching performed according to some embodiments of the present technology can etch titanium and / or tantalum materials while substantially or essentially maintaining any of the metals or silicon-containing materials described above.

[0062] In the foregoing description, for the purposes of explanation, numerous specific details were set forth in order to provide an understanding of various embodiments of the present technology. It will be apparent, however, to one skilled in the art that certain embodiments can be practiced without some or all of these specifics details, or with other methods, components, materials, and so on.

[0063] While several embodiments have been disclosed, it should be apparent that modifications and variations can be made that do not depart from the spirit and scope of the embodiments. It should be noted that many known processes and elements are not described in detail in order to avoid unnecessarily obscuring the present technology. Thus, the above description does not limit the scope of the technology. Additionally, methods or processes described herein are not limited to the order described or the order illustrated, but can be performed in any order.

[0064] Where a range of values is provided, it is understood that each intervening value, to the lowest unit of the lower limit, and to the highest unit of the upper limit, is also specifically disclosed. For example, if a range of 1 -6 is disclosed, then 3.1, 3.2, 3.3, 3.4, or 3.5 are also disclosed. Any narrower range or value is also specifically disclosed. These are only examples of what is specifically enabled by this application, and they are intended to be construed to cover any number falling within the explicitly recited range. All ranges are inclusive of the endpoints.

[0065] As used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a precursor" includes more than one such precursor, reference to "the layer" includes reference to one or more layers and equivalents thereof known to those skilled in the art, and so forth.

[0066] Further, as used herein and in the following claims, the terms "comprise(s)," "comprising," "contain(s)," "containing," "include(s)," and "including" when used in this manner, indicate the presence of stated features, integers, steps, or components but do not preclude the presence or addition of one or more other features, integers, steps, components, actions, or groups thereof.

Claims

1. An etching method comprising the following steps: Fluorine-containing precursors and hydrogen-containing precursors are fed into a remote plasma region of a semiconductor processing chamber, wherein the hydrogen-containing precursors are flowed at a flow rate of at least 2:1 relative to the flow rate of the fluorine-containing precursors. A plasma containing the fluorine-containing precursor and the hydrogen-containing precursor is formed to generate a plasma effluent; The plasma outflow is directed to a substrate processing area containing a substrate, wherein the substrate includes an exposed area of ​​tantalum or titanium material and an exposed area of ​​silicon material. Contact the substrate with the plasma effluent; and The tantalum or titanium material is selectively removed relative to the silicon-containing material.

2. The etching method of claim 1, wherein the tantalum or titanium material comprises tantalum or titanium metal or tantalum or titanium oxide or nitride.

3. The etching method of claim 1, wherein the substrate further includes an exposed area of ​​metal, the metal comprising tungsten, cobalt or copper.

4. The etching method of claim 1, wherein the plasma power is maintained at less than or equal to 1,000 W.

5. The etching method of claim 1, wherein the etching method is performed at a temperature of 150°C or higher.

6. The etching method of claim 1, wherein the etching method is performed at a pressure of less than or equal to 10 Torr.

7. The etching method of claim 1, further comprising: A pretreatment performed before the fluorinated precursor is allowed to flow, wherein the pretreatment comprises contacting the substrate with a plasma comprising one or more of oxygen, hydrogen, water vapor, or nitrogen.

8. The etching method of claim 1, further comprising: A post-processing performed after the etching method, wherein the post-processing includes contacting the substrate with a plasma comprising one or more of hydrogen, nitrogen, oxygen, or water vapor.

9. The etching method of claim 1, further comprising: The substrate is removed from the semiconductor processing chamber, and Residues are removed from the chamber walls of the semiconductor processing chamber.

10. The etching method of claim 9, wherein removing the residue comprises: Provide chlorine-containing precursors or their plasma effluents, or bromine-containing precursors or their plasma effluents.

11. An etching method comprising the following steps: Forming a plasma containing one or more of oxygen, hydrogen, or nitrogen as a processing precursor to produce a processing plasma effluent; The processing plasma outflow is directed to the substrate processing area of ​​the semiconductor processing chamber; The processed plasma effluent is used to contact the substrate contained in the substrate processing area, wherein the substrate defines an exposed area of ​​tantalum or titanium material and an exposed area of ​​tungsten, cobalt or copper. Remove carbon-containing material from the surface of the tantalum or titanium material; Plasma containing fluorine and hydrogen precursors is formed; The substrate is contacted with plasma effluent; Remove the tantalum or titanium material; as well as After the tantalum or titanium material is removed and before the substrate is removed from the semiconductor processing chamber, the substrate is contacted with a hydrogen-containing plasma, wherein the etching method is performed at a temperature of 500°C or higher.

12. The etching method of claim 11, wherein the hydrogen-containing precursor is flowed relative to the fluorine-containing precursor at a rate greater than or equal to 2:

1.

13. The etching method of claim 11, wherein the plasma power during the formation of the fluorine-containing precursor is maintained at less than or equal to 1,000 W.

14. The etching method of claim 11, wherein the etching method is performed at a temperature of 300°C or higher.

15. The etching method of claim 11, wherein the etching method is performed at a pressure of less than or equal to 10 Torr.

16. The etching method of claim 11, further comprising: a post-processing performed after the etching method, wherein the post-processing comprises: contacting the substrate with a hydrogen-containing plasma.

17. The etching method of claim 11, further comprising: Remove the substrate from the semiconductor processing chamber, and Residues are removed from the chamber walls of the semiconductor processing chamber.

18. An etching method comprising the following steps: Fluorine-containing precursors and hydrogen-containing precursors are fed into a remote plasma region of a semiconductor processing chamber, wherein the hydrogen-containing precursors are flowed at a flow rate of at least 2:1 relative to the flow rate of the fluorine-containing precursors. A plasma containing the fluorine-containing precursor and the hydrogen-containing precursor is formed to generate a plasma effluent; The plasma effluent is directed to a substrate processing area containing a substrate, wherein the substrate includes an exposed area of ​​tantalum or titanium material and an exposed area of ​​silicon or metal material. The plasma effluent is used to contact the substrate; Selective removal of the tantalum or titanium material relative to the silicon-containing material or the metal; A plasma containing hydrogen-containing processing precursors is formed to produce a processing plasma effluent; and The substrate is contacted with the processed plasma effluent, wherein the etching method is performed at a temperature above 500°C.

19. The etching method of claim 18, wherein the processing plasma effluent is configured to remove residual fluorine from one or more of the substrate or the semiconductor processing chamber.

20. The etching method of claim 18, further comprising: Remove the substrate from the semiconductor processing chamber, and The residue is removed from the chamber wall of the semiconductor processing chamber using a chlorine-containing precursor.

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