System and method for titanium-containing film removal

Abstract

An exemplary semiconductor processing method may include flowing an etchant precursor into a processing region of a semiconductor processing chamber. A substrate may be received within the processing region. The substrate may define an exposed region of a titanium-containing material. This method may include contacting the substrate with the etchant precursor. The method may include removing at least a portion of the titanium-containing material.

Description

Technical Field

[0001] This application claims the benefit of and priority to U.S. patent application No. 18 / 101,932, filed on January 26, 2023, entitled “SYSTEMS AND METHODS FORTITANIUM-CONTAINING FILM REMOVAL,” which is incorporated herein by reference in its entirety.

[0002] The present technology relates to semiconductor processing and equipment and, more particularly, to selectively etching titanium-containing structures. Background Art

[0003] Integrated circuits are made possible by processes that produce complex, patterned layers of material on a substrate surface. Producing patterned material on a substrate requires a controlled method for removing exposed material. Chemical etching is used for a variety of purposes, including transferring a pattern in a photoresist into an underlying layer, thinning a layer, or thinning the lateral dimensions of a pre-existing feature on a surface. It is often desirable to have an etch process that etches one material faster than another, for example, to facilitate pattern transfer. Such an etch process is said to be selective for the first material. Due to the diversity of materials, circuits, and processes, etch processes have been developed that have selectivity for a variety of materials.

[0004] Depending on the materials used in the process, etching processes can be described as wet or dry. For example, wet etching can preferentially remove some oxide dielectrics over other dielectrics and materials. However, wet etching can have difficulty penetrating certain confined trenches and can sometimes deform the remaining material. Dry etching, generated in a localized plasma formed within the substrate processing area, can penetrate more confined trenches and exhibit less deformation of the fine remaining structure. However, the localized plasma can damage the substrate through arcing during discharge.

[0005] Therefore, there is a need for improved systems and methods that can be used to produce high quality components and structures. These and other needs are addressed by the present technology. Summary of the Invention

[0006] An exemplary semiconductor processing method may include flowing an etchant precursor into a processing region of a semiconductor processing chamber. A substrate may be housed within the processing region. The substrate may define an exposed region of a titanium-containing material. The method may include contacting the substrate with the etchant precursor. The method may include removing at least a portion of the titanium-containing material.

[0007] In some embodiments, the etchant precursor may be or include a halogen-containing precursor. The etchant precursor may be or include a chlorine-containing precursor. The chlorine-containing precursor may be or include thionyl chloride (SOCl2). Removing a portion of the titanium-containing material may be performed in the absence of a plasma. Removing a portion of the titanium-containing material may be performed at a temperature of less than or about 450°C. Removing a portion of the titanium-containing material may be performed at a pressure greater than or about 0.1 Torr. Removing a portion of the titanium-containing material may be performed at a pressure less than or about 50 Torr. The methods may include a pre-treatment performed prior to flowing the etchant precursor. The pre-treatment may include contacting the substrate with a plasma comprising one or more of oxygen, hydrogen, or nitrogen. The methods may include a post-treatment performed after removing the portion of the titanium-containing material. The post-treatment may include contacting the substrate with a plasma comprising one or more of oxygen, hydrogen, or nitrogen.

[0008] Some embodiments of the present technology may encompass semiconductor processing methods. The methods may include forming a plasma comprising a processing precursor of one or more of oxygen, hydrogen, or nitrogen to produce a processing plasma effluent. The methods may include flowing the processing plasma effluent into a processing region of a semiconductor processing chamber. A substrate may be housed within the processing region. The substrate may define an exposed area of ​​a titanium-containing material. The methods may include contacting the substrate with the processing plasma effluent. The processing plasma effluent may be configured to remove residue from a surface of the titanium-containing material. The methods may include flowing an etchant precursor into the processing region of the semiconductor processing chamber. The methods may include contacting the substrate with the etchant precursor. The methods may include removing at least a portion of the titanium-containing material.

[0009] In some embodiments, the methods may include stopping formation of a plasma of a treatment precursor before flowing the etchant precursor. The etchant precursor may be or include thionyl chloride (SOCl2). Removing the portion of the titanium-containing material may be performed at a temperature of less than or about 400°C. Removing the portion of the titanium-containing material may be performed at a pressure of less than or about 30 Torr. The methods may include post-processing after removing the portion of the titanium-containing material. Post-processing may include contacting the substrate with a plasma comprising one or more of oxygen, hydrogen, or nitrogen.

[0010] Some embodiments of the present technology may include semiconductor processing methods. The methods may include flowing an etchant precursor into a processing region of a semiconductor processing chamber. A substrate may be housed within the processing region. The substrate may define an exposed region of a titanium-containing material. The methods may include contacting the substrate with the etchant precursor. The methods may include removing at least a portion of the titanium-containing material. The methods may include forming a plasma comprising a processing precursor comprising one or more of oxygen, hydrogen, or nitrogen to produce a processing plasma effluent. The methods may include contacting the substrate with the processing plasma effluent.

[0011] In some embodiments, the etchant precursor may include chlorine. Processing the plasma effluent may be configured to remove residual chlorine from one or more of the substrate or the semiconductor processing chamber. Removing the portion of the titanium-containing material may be performed at a temperature of less than or about 380° C. and a pressure of less than or about 30 Torr.

[0012] This technology can provide numerous advantages over conventional systems and techniques. For example, the processes can allow for dry etching that can protect substrate features. Additionally, the processes can selectively remove titanium-containing films relative to other exposed materials on the substrate. These and other embodiments are described in greater detail (along with their numerous advantages and features) in conjunction with the following description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] A further understanding of the nature and advantages of the disclosed technology may be realized by reference to the remaining portions of the specification and the accompanying drawings.

[0014] Figure 1 A top view of one embodiment of an exemplary processing system is shown in accordance with some embodiments of the present technology.

[0015] Figure 2A A schematic cross-sectional view of an exemplary processing chamber is shown, in accordance with some embodiments of the present technology.

[0016] Figure 2B Some embodiments of the present technology are shown Figure 2A Detailed view of a portion of a processing chamber is shown in FIG.

[0017] Figure 3 A bottom view of an exemplary showerhead is shown in accordance with some embodiments of the present technology.

[0018] Figure 4 Exemplary operations in a method according to some embodiments of the present technology are shown.

[0019] Figures 5A-5B A schematic cross-sectional view of etched material is shown in accordance with some embodiments of the present technology.

[0020] Several figures are included as schematic diagrams. It should be understood that the figures are for illustration purposes only and should not be considered to be drawn to scale unless specifically indicated as such. Furthermore, as schematic diagrams, the figures are provided to aid understanding and may not include all aspects or information compared to realistic representations and may include additional or exaggerated material for illustrative purposes.

[0021] In the drawings, similar components and / or features may be given the same reference numerals. Furthermore, various components of the same type may be distinguished by following the reference numeral with a letter that distinguishes the similar components. If only the first reference numeral is used in the specification, the description applies to any similar component having the same first reference numeral, regardless of the letter. DETAILED DESCRIPTION

[0022] Dilute acids can be used in many different semiconductor processes to clean substrates and remove materials from those substrates. For example, dilute hydrofluoric acid ("DHF") can be an effective etchant for silicon oxide, aluminum oxide, titanium oxide, and other materials, and can be used to remove these materials from substrate surfaces. After the etching or cleaning operation is completed, the acid can be dried from the wafer or substrate surface. The use of DHF can be referred to as "wet" etching, where the diluent is typically water. Additional etching processes can be used that utilize precursors delivered to the substrate. For example, plasma-enhanced processes can also selectively etch materials through plasma-enhanced precursors to perform dry etching.

[0023] While wet etchants using aqueous solutions or water-based processes can be effective for certain substrate structures, water can present challenges under various conditions. For example, when applied to substrates comprising metal materials, the use of water during the etching process can pose problems. For example, certain post-manufacturing processes, such as recessing gaps, removing oxide dielectrics, or other processes to remove oxygen-containing materials, may be performed after a certain amount of metallization has been formed on the substrate. If water is used in certain circumstances during the etching process, it may create an electrolyte that, when in contact with the metal material, can cause galvanic corrosion between dissimilar metals, potentially corroding or displacing the metal during various processes. Furthermore, due to the surface tension of the water diluent, microstructures may experience pattern distortion and collapse. Due to surface tension effects, water-based substrates may also be unable to penetrate some high-aspect ratio features. Plasma etching can overcome the issues associated with water-based etching, although other issues may arise. For example, reactive ion etching processes may expose the metal to ionic activity, which can damage the structure through bombardment and affect electrical properties.

[0024] The present technology overcomes these issues by performing a dry etching process that can passivate a variety of materials relative to the material being etched, and in some embodiments, the process can be plasma-free during etching. By utilizing a specific precursor that promotes halogen dissociation to provide the etchant material, an etching process can be performed that protects surrounding structures. Additionally, the materials and conditions used can allow for improved etching relative to conventional techniques.

[0025] While the remainder of the disclosure will conventionally identify a particular etching process utilizing the disclosed techniques, it will be readily understood that the systems and methods are equally applicable to deposition and cleaning processes that may occur in the described chambers, as well as other etching techniques and other etches that may be performed with various exposed materials that may be maintained or substantially maintained. Therefore, the techniques should not be considered limited to use with only the exemplary etching processes or chambers. Furthermore, while an exemplary chamber is described to provide a basis for the present techniques, it should be understood that the present techniques are applicable to virtually any semiconductor processing chamber that can permit the described operations.

[0026] Figure 1 A top view of one embodiment of a processing system 100 for deposition, etching, baking, and curing chambers according to an embodiment is shown. In the figure, a pair of front-opening unified pods (FOUPs) 102 provide substrates of various sizes, which are received by a robot 104 and placed in a low-pressure holding area 106 and then placed into one of the substrate processing chambers 108a-f, which are located in series 109a-c. A second robot 110 can be used to transfer substrate wafers from the holding area 106 to the substrate processing chambers 108a-f and back. Each substrate processing chamber 108a-f can be equipped to perform a variety of substrate processing operations, including dry etching processes described herein, in addition to cyclic layer deposition (CLD), atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), etching, pre-cleaning, degassing, orientation, and other substrate processing.

[0027] The substrate processing chambers 108a-f may include one or more system components for depositing, annealing, curing, and / or etching dielectric films on substrate wafers. In one configuration, two pairs of processing chambers (e.g., 108c-d and 108e-f) may be used to deposit dielectric material on a substrate, while a third pair of processing chambers (e.g., 108a-b) may be used to etch the deposited dielectric. In another configuration, all three pairs of chambers (e.g., 108a-f) may be configured to etch dielectric films on a substrate. Any one or more of the processes described may be performed in a chamber separate from the manufacturing system shown in various embodiments. It should be understood that the system 100 contemplates additional configurations of chambers for deposition, etching, annealing, and curing of dielectric films.

[0028] Figure 2AA cross-sectional view of an exemplary processing chamber system 200 having a separate plasma generation region within the processing chamber is shown. During film etching (e.g., titanium nitride, tantalum nitride, tungsten, silicon, polysilicon, silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, etc.), a process gas can flow through a gas inlet assembly 205 into a first plasma region 215. A remote plasma system (RPS) 201 can optionally be included in the system and can process a first gas that then passes through the gas inlet assembly 205. The inlet assembly 205 can include two or more different gas supply channels, wherein a second channel (not shown) can bypass the RPS 201 (if included).

[0029] The cooling plate 203, the faceplate 217, the ion suppressor 223, the showerhead 225, and the pedestal 265 or substrate support on which the substrate 255 is disposed are shown and can each be included depending on the embodiment. The pedestal 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 plate of the pedestal 265 (which can include aluminum, ceramic, or a combination thereof) can also be resistively heated using embedded resistive heating elements to achieve relatively high temperatures (e.g., from up to or about 100° C. to greater than or about 1100° C.).

[0030] The faceplate 217 may be pyramidal, conical, or another similar structure having a narrow top that expands to a wide base. As shown, the faceplate 217 may also be flat and include a plurality of through-channels for distributing process gases. Depending on the use of the RPS 201, the plasma generating gas and / or plasma exciting species may pass through a plurality of holes in the faceplate 217 (as shown in FIG. Figure 2B ), for more uniform delivery into the first plasma region 215.

[0031] An exemplary configuration may include opening the gas inlet assembly 205 into a gas supply region 258 that is separated from the first plasma region 215 by a faceplate 217, such that gas / species flow through holes in the faceplate 217 and into the first plasma region 215. Structural and operational features may be selected to prevent significant backflow of plasma from the first plasma region 215 back into the supply region 258, the gas inlet assembly 205, and the fluid supply system 210. The faceplate 217 (or the conductive top of the chamber) and the showerhead 225 are shown with an insulating ring 220 located between the features, which allows an AC potential to be applied to the faceplate 217 relative to the showerhead 225 and / or the ion suppressor 223. The insulating ring 220 may be positioned between the faceplate 217 and the showerhead 225 and / or the ion suppressor 223 to enable a capacitively coupled plasma to form in the first plasma region. A baffle (not shown) may additionally be located in the first plasma region 215 or otherwise coupled to the gas inlet assembly 205 to influence the flow of fluid through the gas inlet assembly 205 into this region.

[0032] The ion suppressor 223 may comprise a plate or other geometric shape defining a plurality of apertures throughout the structure. These apertures are configured to suppress the migration of ionically charged species out of the first plasma region 215 while allowing uncharged neutral or radical species to pass through the ion suppressor 223 and into the reactive gas transport region between the suppressor and the showerhead. In embodiments, the ion suppressor 223 may comprise a perforated plate having a variety of aperture configurations. These uncharged species may include highly reactive species that are transported through the apertures along with a less reactive carrier gas. As described above, the migration of ionic species through the apertures can be reduced, and in some cases, completely suppressed. Controlling the amount of ionic species passing through the ion suppressor 223 can advantageously provide enhanced control over the gas mixture that contacts the underlying wafer substrate, which in turn can enhance control over the deposition and / or etching characteristics of the gas mixture. For example, adjusting the ion concentration of the gas mixture can significantly alter its etch selectivity. In alternative embodiments performing deposition, it can also alter the balance between conformal and flowable deposition of dielectric materials.

[0033] The plurality of apertures in the ion suppressor 223 can be configured to control the passage of activated gas (i.e., ions, radicals, and / or neutral species) through the ion suppressor 223. For example, the aspect ratio of the apertures, or the aperture diameter to length, and / or the aperture geometry can be controlled to reduce the flow of ionically charged species in the activated gas through the ion suppressor 223. The apertures in the ion suppressor 223 can include a tapered 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 designed to control the flow of ion species delivered 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.

[0034] The ion suppressor 223 can function 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, ionically charged species in the reaction zone surrounding the substrate may not be completely eliminated. In some cases, ionized species are intended to reach the substrate to perform etching and / or deposition processes. In these cases, the ion suppressor may help control the concentration of ionized species in the reaction zone to a level that is conducive to the process.

[0035] The showerhead 225, in combination with the ion suppressor 223, can allow the plasma present in the first plasma region 215 to avoid directly exciting gases 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 way, the chamber can be configured to prevent the plasma from contacting the substrate 255 being etched. This can advantageously protect various complex structures and films patterned on the substrate, which could be damaged, misaligned, or otherwise warped if directly exposed to the generated plasma. Additionally, the rate at which oxide species are etched can increase when the plasma is allowed to contact the substrate or near the level of the substrate. Therefore, if the exposed area of ​​the material is an oxide, the material can be further protected by keeping the plasma away from the substrate.

[0036] The processing system may also include a power supply 240 electrically coupled to the processing chamber to provide power to the faceplate 217, the ion suppressor 223, the showerhead 225, and / or the pedestal 265 to generate a plasma in the first plasma region 215 or the 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. This configuration may allow a tunable plasma to be used in the process being performed. Unlike a remote plasma unit that typically has an on or off function, a tunable plasma may be configured to deliver a specific amount of power to the plasma region 215. This, in turn, may allow for the development of specific plasma characteristics so that precursors may be dissociated in a specific manner to enhance the etch profile produced by these precursors.

[0037] A plasma may be ignited in the chamber plasma region 215 above the showerhead 225 or in the substrate processing region 233 below the showerhead 225. A plasma may be present in the chamber plasma region 215 to generate radical precursors from, for example, an inflow of a fluorine-containing precursor or other precursor. An AC voltage, typically in the radio frequency (RF) range, may be applied between the conductive top of the processing chamber (e.g., 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 may generate a high RF frequency of 13.56 MHz, but other frequencies may also be generated, alone or in combination with the 13.56 MHz frequency.

[0038] Figure 2B A detailed view 253 is shown showing features that affect the distribution of process gases through the panel 217. Figure 2A and 2B As shown, the faceplate 217, the cooling plate 203, and the gas inlet assembly 205 intersect to define a gas supply region 258 to which process gas can be delivered from the gas inlet 205. The gas can fill the gas supply region 258 and flow through holes 259 in the faceplate 217 to the first plasma region 215. The holes 259 can be configured to direct the flow in a substantially unidirectional manner such that the process gas can flow into the processing region 233, but can be partially or completely prevented from flowing back into the gas supply region 258 after passing through the faceplate 217.

[0039] The gas distribution assembly used in the process chamber portion 200, such as the showerhead 225, may be referred to as a dual channel showerhead (DCSH) and is Figure 3 The dual channel showerhead can provide an etch process that allows the etchant to be separated outside of the processing region 233 to provide limited interaction with chamber components and each other before being delivered to the processing region.

[0040] Showerhead 225 can include an upper plate 214 and a lower plate 216. The plates can be coupled to each other to define a volume 218 therebetween. The coupling of the plates can provide a first fluid channel 219 through the upper and lower plates, and a second fluid channel 221 through the lower plate 216. The resulting channels can be configured to provide fluid access from volume 218 through lower plate 216 and only through second fluid channel 221, and first fluid channel 219 can be fluidically isolated from volume 218 between the plates and second fluid channel 221. Volume 218 can be fluidically accessed through one side of showerhead 225.

[0041] 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 Figure 2A Shown is a showerhead 225. The through-holes 365, showing a view of the first fluid channel 219, can have a variety of shapes and configurations to control and influence the flow of precursors through the showerhead 225. The small holes 375, showing a view of the second fluid channel 221, can be substantially evenly distributed across the surface of the showerhead, even between the through-holes 365, and can help provide more uniform mixing of the precursors as they exit the showerhead than other configurations.

[0042] The chambers discussed previously can be used to perform exemplary methods including etching methods. Figure 4 , which illustrates exemplary operations in a method 400 according to an embodiment of the present technology. The method 400 may include one or more operations before the method begins, including front-end processing, deposition, gate formation, etching, polishing, cleaning, or any other operation that may be performed before the described operations. The method may include a number of optional operations that may or may not be specifically associated with some embodiments of the method according to the present technology. For example, many operations are described to provide a broader scope of processing performed, but are not critical to the technology or may be performed via alternative methods as discussed further below. The method 400 may describe Figures 5A-5B The operations schematically illustrated in FIG will be described in conjunction with the operations of method 400. It should be understood that the drawings are only partial schematics and that the substrate may include any number of additional materials and features having the various properties and aspects shown.

[0043] The method 400 may or may not involve the optional operation of developing the semiconductor structure into a specific manufacturing operation. It should be understood that the method 400 can be performed on any number of semiconductor structures or substrates 505, such as Figure 5A, including exemplary structures on which nitride removal operations may be performed. The exemplary semiconductor structure may include trenches, vias, or other recessed features that may include one or more exposed materials. For example, the exemplary substrate may include silicon or some other semiconductor substrate material and an interlayer dielectric material through which recesses, trenches, vias, or isolation structures may be formed. The material exposed at any time during the etching process may be or include a metal material such as a gate, a dielectric material, a contact material, a transistor material, or any other material that may be used in semiconductor processing. In some embodiments, the exemplary structure 500 may include a metal-containing region 510 extending into the substrate 505, such as a tungsten-containing material. An aluminum-containing material 515 may cover a portion of the substrate 505. A low dielectric constant material 520, such as silicon oxide, may extend from the aluminum-containing material 515. A titanium-containing material 525, such as titanium nitride, may cover the low dielectric constant material 520. As Figure 5A As shown, titanium-containing material 525 may be exposed relative to one or more other materials, including metal-containing materials, dielectric materials including silicon oxide, or any number of other semiconductor materials relative to which the titanium-containing material is to be removed, such as aluminum oxide and any other material.

[0044] It should be understood that the structures mentioned are not intended to be limiting and similarly encompass any of a variety of other semiconductor structures that include titanium-containing materials. Other exemplary structures may include two-dimensional and three-dimensional structures commonly found in semiconductor manufacturing, and in which titanium-containing materials, such as titanium nitride, are to be removed relative to one or more other materials, as the present technique can selectively remove titanium-containing materials relative to other exposed materials, such as silicon-containing materials, metal-containing materials, oxides and other nitrides, and any other materials discussed elsewhere. Additionally, while high aspect ratio structures may benefit from the present technique, the technique can be equally applicable to lower aspect ratio and any other structures.

[0045] For example, a material layer according to the present technology can be characterized by any aspect ratio or height-to-width ratio of the structure, although in some embodiments, the material can be characterized by a larger aspect ratio, which may not allow for sufficient etching using conventional techniques or methods. For example, in some embodiments, the aspect ratio of any layer of the 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. In addition, each layer can be characterized by a reduced width or thickness of 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 5 nm, less than or about 1 nm, or less, including any fraction of any of the aforementioned numbers, such as 20.5 nm, 1.5 nm, etc. This combination of a high aspect ratio and a minimum thickness can hinder many conventional etching operations or require a considerable etching time (along a vertical or horizontal distance through a limited width) to remove the layer. Additionally, damage or removal of other exposed layers may also occur with conventional techniques.

[0046] In embodiments, method 400 may be performed to remove exposed titanium-containing material, although any number of nitrides or titanium-containing materials may be removed in any number of structures in embodiments of the present technology. Such methods may include specific operations for removing titanium-containing materials and may include one or more optional operations to prepare or treat titanium-containing materials. For example, an exemplary substrate structure may have previous processing residues on the film to be removed, such as titanium nitride. For example, residual photoresist or byproducts from previous processing may reside on the titanium nitride layer. These materials may prevent access to the titanium nitride or may interact with the etchant differently than a clean titanium nitride surface, which may hinder one or more aspects of etching. Therefore, in some embodiments, optional pre-treatment of the titanium-containing film or material may be performed at optional operation 405. Exemplary pre-treatment operations may include, for example, thermal treatment, wet treatment, or plasma treatment, which may be performed in chamber 200 and any number of chambers that may be included on the above-described system 100.

[0047] In one exemplary plasma treatment, a remote or localized plasma can be generated from a precursor that is intended to interact with the residue in one or more ways. For example, using a chamber such as chamber 200 described above, a remote or localized 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, or some other precursor can be flowed into a remote plasma region or a treatment region where a plasma can be bombarded. The plasma effluent can flow to the substrate and can contact the residual material. The plasma treatment can be a physical treatment or a chemical treatment, depending on the material to be removed to expose the titanium-containing material. For example, the plasma effluent can flow to contact and physically remove the residue, such as through a sputtering operation, or the precursor can flow to interact with the residue to produce volatile byproducts that can be removed from the chamber.

[0048] Exemplary precursors used in the pretreatment may be or include hydrogen, hydrocarbons, water vapor, alcohols, hydrogen peroxide, or other materials that may include hydrogen as will be understood by one of ordinary skill in the art. Exemplary oxygen-containing precursors may include molecular oxygen, ozone, nitrous oxide, nitric oxide, or other oxygen-containing materials. Nitrogen may also be used, or a combination of precursors having one or more of hydrogen, oxygen, and / or nitrogen may be utilized to remove specific residues. Once the residues or byproducts are removed, the clean titanium nitride surface may be exposed for etching. The halogen-containing precursor may be flowed through a remote plasma region of the processing chamber, such as region 215 described above, although in some embodiments, method 400 may not utilize plasma effluents during the etching operation. For example, method 400 may flow a fluorine-containing or other halogen-containing precursor to the substrate without exposing the precursor to a plasma, and may perform the removal of the titanium-containing material without generating plasma effluents. In some embodiments, the halogen-containing precursor may be plasma-enhanced, which may occur in the remote plasma region to protect materials on the substrate from contact with the plasma effluents. A halogen-containing precursor can contact a semiconductor substrate including an exposed titanium-containing material and can produce a fluorinated material, such as a titanium fluoride or titanium halide material, that can remain on the semiconductor substrate. In some embodiments, the halogen-containing precursor can provide one or more fluorine atoms while accepting one or more oxygen atoms. Some halogen-containing precursors, such as plasma-enhanced precursors, can provide fluorine radicals, while other plasma radicals can accept oxygen from the film.

[0049] Method 400 may include (at operation 410) flowing an etchant precursor into a substrate processing region of a semiconductor processing chamber containing the described substrate or some other substrate. The etchant precursor may flow through a remote plasma region of the processing chamber, such as region 215 described above, although in some embodiments, method 400 may not utilize plasma effluents during the etching operation. For example, method 400 may flow the etchant precursor to the substrate without exposing the precursor to a plasma, and may perform the removal of titanium-containing materials without generating plasma effluents. In some embodiments, the etchant precursor may be plasma-enhanced, which may occur in the remote plasma region to protect materials on the substrate from contact with the plasma effluents. The etchant precursor may contact the semiconductor substrate including exposed regions of titanium-containing material and may generate a chlorinated material (e.g., titanium fluorochloride or titanium halide material), which may remain on the semiconductor substrate or volatilize. In some embodiments, a halogen-containing precursor may provide one or more chlorine atoms while accepting one or more nitrogen atoms. Some halogen-containing precursors (e.g., plasma-enhanced precursors) may provide chlorine radicals, while other plasma radicals may accept nitrogen from the film. Thus, at operation 415, the etchant precursor may etch or remove the titanium-containing material, such as Figure 5B shown.

[0050] As described above, the present technology can be performed without plasma development during etching operations 410-415. By utilizing specific precursors and etching under certain processing conditions, plasma-free removal can be performed, and the removal can also be dry etching. Therefore, techniques according to various aspects of the present technology can be performed to remove titanium nitride from narrow features, as well as high aspect ratio features and thin dimensions, which may otherwise be unsuitable for wet etching. Optional operations can be performed to clean residues from the substrate or chamber and can include post-processing at optional operation 420. Post-processing can include operations similar to pre-processing and can include any of the precursors or operations discussed above for pre-processing. In some embodiments, post-processing can remove residual etchant, such as chlorine, from the substrate or chamber. It should be understood that although pre-processing and / or post-processing operations may include plasma generation and delivery of plasma effluent to the substrate, plasma may not be formed during etching operations 410-415. For example, in some embodiments, plasma may not be generated when one or more etchant precursors are delivered to the processing chamber.

[0051] The etchant precursor during etching operations 410-415 may include a halogen-containing precursor, and in some embodiments may include one or more of fluorine or chlorine. The specific precursor may be based on the bonding or stability of the precursor. Exemplary etchant precursors may include thionyl chloride (SOCl2), and halogen-containing precursors, such as other chlorine-containing precursors or fluorine-containing precursors. The etchant may also flow with various other precursors. In some embodiments, in addition to the etchant precursor, boron trichloride (BCl3), nitrogen trifluoride (NF3), tungsten hexafluoride (WF6) or other halogen-containing precursors may be selectively transported to a remote plasma region to perform plasma enhancement before flowing to the processing region. In an embodiment, a hydrogen-containing precursor, such as molecular hydrogen (H2), may be provided to the etchant precursor. Any number of carrier gases may also be provided to the etchant precursor, which may include nitrogen, helium, argon or other rare, inert or useful precursors. The carrier gas may be used to dilute the etchant precursor, control the etching rate, and distribute the etchant precursor.

[0052] As a non-limiting example, thionyl chloride (SOCl2) can easily provide one or two chlorine atoms and oxygen atoms at elevated temperatures, and accept nitrogen atoms such as from titanium nitride, and remain in the gas phase. Therefore, titanium-containing materials can be produced as reaction byproducts, which can be gas molecules and can be pumped or removed from the processing chamber. For example, chlorine from an etchant precursor can be combined with titanium nitride to form titanium tetrachloride (TiCl4), titanium (III) chloride (TiCl3) or titanium oxychloride (TiOCl2). In addition, nitrogen-containing materials can be produced as reaction byproducts, which can be gas molecules and can be pumped or removed from the processing chamber. For example, nitrogen from titanium nitride can form stable byproducts, such as diatomic nitrogen (N2), nitrous oxide (N2O) or nitrogen dioxide (NO2). In addition, sulfur-containing materials can be produced as reaction byproducts, which can be gas molecules and can be pumped or removed from the processing chamber. For example, residual sulfur from the etchant precursor can be in the form of sulfur dioxide (SO2), sulfur monoxide (SO) or disulfur dichloride (S2Cl2). Therefore, the process can remove titanium nitride under process conditions configured to exchange chlorine and nitrogen between the etchant precursor and the exposed titanium nitride areas, which can produce volatile byproducts. Due to the controlled delivery and processing, the chlorine-containing material is not etched or the interaction with other exposed surfaces is minimized, while the titanium nitride is easily removed, which can produce higher selectivity than traditional techniques.

[0053] Processing conditions can influence and promote etching according to the present technology. Because the etching reaction can proceed based on the thermal dissociation of halogens from the etchant precursor, the temperature can depend at least in part on the specific halogens and / or other atoms of the etchant precursor to initiate dissociation. For example, when the temperature increases to above or about 250°C, etching begins to occur or increases, which can indicate the activation of precursor dissociation and / or reaction with titanium nitride. As the temperature continues to increase, the dissociation and reaction with titanium nitride can be further promoted.

[0054] Thus, in some embodiments of the present technology, the etching method can be performed at a substrate, susceptor, and / or chamber temperature of less than or about 450°C, and can be performed at a temperature of less than or about 440°C, or less than or about 430°C, less than or about 420°C, less than or about 410°C, less than or about 400°C, less than or about 390°C, less than or about 380°C, less than or about 370°C, less than or about 360°C, less than or about 350°C, or less. The temperature can also be maintained at any temperature within these ranges, within smaller ranges encompassed by these ranges, or between any of these ranges. In some embodiments, the method can be performed on a substrate that can have multiple features produced, which can result in a thermal budget. In embodiments, higher temperatures can increase etching of the titanium-containing material 425. Thus, in some embodiments, the methods can be performed at a temperature greater than or about 300°C, and can be performed at a temperature greater than or about 310°C, greater than or about 320°C, greater than or about 330°C, greater than or about 340°C, greater than or about 350°C, greater than or about 360°C, or more.

[0055] The pressure within the chamber can also affect the operations performed and the temperature at which the etchant precursor can dissociate, such as the temperature at which sulfur, oxygen, and chlorine can dissociate when thionyl chloride (SOCl2) is used as the etchant precursor. Thus, in some embodiments, the pressure can be maintained at greater than or about 0.5 Torr, greater than or about 1 Torr, greater than or about 2 Torr, greater than or about 3 Torr, greater than or about 4 Torr, greater than or about 5 Torr, greater than or about 6 Torr, greater than or about 7 Torr, greater than or about 8 Torr, greater than or about 9 Torr, greater than or about 10 Torr, greater than or about 15 Torr, greater than or about 20 Torr, greater than or about 25 Torr, greater than or about 30 Torr, or higher. In addition, the pressure can be maintained at less than or about 50 Torr, less than or about 40 Torr, less than or about 30 Torr, less than or about 25 Torr, less than or about 20 Torr, less than or about 15 Torr, less than or about 10 Torr, less than or about 9 Torr, less than or about 8 Torr, less than or about 7 Torr, less than or about 6 Torr, less than or about 5 Torr, less than or about 4 Torr, less than or about 3 Torr, less than or about 2 Torr, less than or about 1 Torr, less than or about 0.1 Torr, or less. The pressure can also be maintained within these ranges, within the smaller ranges encompassed by these ranges, or within any range within these ranges. In some embodiments, the amount of etching can be promoted and can begin when the pressure is increased to greater than about 0.5 Torr. In addition, as the pressure continues to increase, the etching may improve to a certain extent, then begin to decrease, and ultimately stop as the pressure continues to increase.

[0056] Without being bound by any particular theory, the pressure within the chamber can affect processing using the above-mentioned precursors. At low pressures, flow through the substrate can be reduced, and dissociation can be similarly reduced. As pressure increases, the interaction between the etchant precursor and the substrate may increase, which may increase the reaction and etch rates. However, as the pressure continues to increase, due to the relative stability of the molecules, the recombination of the dissociated etchant precursor atoms may increase. Therefore, the precursor can be effectively pumped back out of the chamber without reacting with the substrate. In addition, as the pressure continues to increase, the interaction with the titanium nitride surface may be suppressed, or the byproduct titanium chloride may be reintroduced into the etched film, further limiting removal. Therefore, in some embodiments, the pressure within the processing chamber can be maintained at less than or about 30 Torr.

[0057] The flow rate of the etchant precursor can be adjusted, including in-situ adjustment, to control the etching process. For example, the flow rate of the etchant precursor can be reduced, maintained, or increased during the removal operation. By increasing the flow rate of the etchant precursor, the etching rate can be increased to a saturation point. During any operation of method 400, the flow rate of the etchant precursor can be between about 5 sccm and about 1,000 sccm. In addition, the flow rate of the etchant precursor can be maintained at less than or about 900 sccm, less than or about 800 sccm, less than or about 700 sccm, less than or about 600 sccm, less than or about 500 sccm, less than or about 400 sccm, less than or about 300 sccm, less than or about 200 sccm, less than or about 100 sccm, or less. The flow rate can also be between any one of these specified flow rates, or within a smaller range encompassed by any one of these numbers.

[0058] To add further control over the etching process, in some embodiments, the etchant precursor can be pulsed and can be delivered continuously or in a series of pulses throughout the etching process, which can be consistent or time-varying. The pulsed delivery can be characterized by a first time period during which the etchant precursor flows and a second time period during which the etchant precursor is paused or stopped. In some embodiments, during the second time period, a purge gas can flow during the second time period. The purge gas can be or include nitrogen, helium, argon, or other rare, inert, or useful purge gas. The time periods of any pulsed operation can be similar or different from each other, with any time period being longer. In embodiments, a period of time or continuous flow of the precursor can be for a period of time greater than or about 1 second, and can be 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 encompassed by any of these ranges. For example, in some embodiments, the continuous flow or period of time of the precursor can be carried out for a period of time less than or about 60 seconds, and can be less than or about 45 seconds, less than or about 30 seconds, less than or about 20 seconds, less than or about 15 seconds, less than or about 10 seconds, less than or about 5 seconds, less than or about 4 seconds, less than or about 3 seconds, less than or about 2 seconds, less than or about 1 second, less than or about 0.5 seconds, less than or about 0.1 seconds, or less. In some embodiments, as the delivery of the precursor occurs for a longer time, the etch rate can increase.

[0059] By performing operations according to embodiments of the present technology, titanium nitride or other titanium-containing materials can be selectively etched relative to other materials, including other oxides or nitrides. For example, the present technology can selectively etch titanium oxide relative to exposed areas of metal, dielectrics including silicon-containing materials (including silicon oxide), or other materials. Embodiments of the present technology can etch titanium nitride relative to silicon oxide or any other material at a rate of at least about 2:1, and can etch titanium nitride relative to silicon oxide or other materials at a selectivity of greater than or about 3:1, and can also etch titanium nitride relative to silicon oxide or other materials at a selectivity of greater than or about 4:1, greater than or about 5:1, greater than or about 6:1, greater than or about 7:1, greater than or about 8:1, greater than or about 9:1, greater than or about 10:1, greater than or about 15:1, greater than or about 20:1, greater than or about 25:1, greater than or about 30:1, greater than or about 35:1, greater than or about 40:1, greater than or about 45:1, greater than or about 50:1, or more. For example, etches performed according to some embodiments of the present technology may etch titanium nitride while substantially or essentially retaining silicon oxide or other materials such as nitrides or oxides of silicon, aluminum or hafnium, metals such as tungsten or molybdenum, or materials such as polysilicon.

[0060] Selectivity can be based in part on the precursors used and their ability to dissociate under a more controlled temperature range. Conventional dry etchants may not produce the etch selectivity of embodiments of the present technology. Similarly, because wet etchants readily remove silicon oxide, wet etchants may not selectively etch at rates comparable to embodiments of the present technology.

[0061] The previously discussed methods can allow for the removal of titanium-containing materials relative to many other exposed materials. By utilizing an etchant under the operating conditions previously described, an improved etch of titanium nitride can be performed, which can both increase selectivity relative to conventional techniques and improve etch access in fine pitch features.

[0062] In the foregoing description, for the purpose of explanation, numerous details have been set forth in order to provide an understanding of various embodiments of the present technology. However, it will be apparent to one skilled in the art that certain embodiments may be practiced without some of these details or with additional details.

[0063] Several embodiments have been disclosed, and those skilled in the art will recognize that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the embodiments. In addition, many well-known processes and elements have not been described to avoid unnecessarily obscuring the present technology. Therefore, the above description should not be taken as limiting the scope of the present technology. In addition, methods or processes may be described as sequential or step-by-step, but it should be understood that the operations may be performed simultaneously or in an order different from that listed.

[0064] Where a range of values ​​is provided, it is understood that each intervening value (to the nearest fraction of the unit of the lower limit unless the context clearly dictates otherwise) also specifically discloses the intervening values ​​between the upper and lower limits of that range. Any narrower range between any specified value or unspecified intervening value in a specified range and any other specified or intervening value in that specified range is included. The upper and lower limits of these smaller ranges may independently be included in or excluded from that range, and each range (where one, neither, or both of the limits are included in the smaller range) is also included in the technology, subject to the range specified by any specifically excluded limits. Where the stated range includes one or both limits, ranges excluding one or both of those included limits are also included.

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

[0066] In addition, when the words "comprises," "includes," "includes," and "including" are used in this specification and below, the claims are intended to specify the presence of stated features, integers, components, or operations, but do not preclude the presence or addition of one or more other features, integers, components, operations, actions, or groups.

Claims

1. A semiconductor processing method, comprising: flowing an etchant precursor into a processing region of a semiconductor processing chamber, wherein a substrate is received within the processing region, and wherein the substrate defines an exposed region of a titanium-containing material; contacting the substrate with the etchant precursor; and At least a portion of the titanium-containing material is removed.

2. The semiconductor processing method of claim 1, wherein the etchant precursor comprises a halogen-containing precursor.

3. The semiconductor processing method according to claim 1, wherein: The etchant precursor includes a chlorine-containing precursor.

4. The semiconductor processing method of claim 3, wherein the chlorine-containing precursor comprises thionyl chloride (SOCl2).

5. The semiconductor processing method according to claim 1, wherein: Removing the portion of the titanium-containing material is performed in the absence of a plasma.

6. The semiconductor processing method of claim 1 wherein removing the portion of the titanium-containing material is performed at a temperature of less than or about 450°C.

7. The semiconductor processing method of claim 1 wherein removing the portion of the titanium-containing material is performed at a pressure greater than or about 0.1 Torr.

8. The semiconductor processing method of claim 1 wherein removing the portion of the titanium-containing material is performed at a pressure of less than or about 50 Torr.

9. The semiconductor processing method of claim 1 , further comprising a pretreatment performed prior to flowing the etchant precursor, wherein the pretreatment comprises contacting the substrate with a plasma comprising one or more of oxygen, hydrogen, or nitrogen.

10. The semiconductor processing method of claim 1, further comprising a post-processing performed after removing the portion of the titanium-containing material, wherein the post-processing comprises exposing the substrate to a plasma comprising one or more of oxygen, hydrogen, or nitrogen.

11. A semiconductor processing method, comprising: forming a plasma of a process precursor comprising one or more of oxygen, hydrogen, or nitrogen to produce a process plasma effluent; flowing the processing plasma effluent into a processing region of a semiconductor processing chamber, wherein a substrate is received within the processing region, and wherein the substrate defines an exposed region of a titanium-containing material; contacting the substrate with the treatment plasma effluent, wherein the treatment plasma effluent is configured to remove residue from a surface of the titanium-containing material; flowing an etchant precursor into the processing region of the semiconductor processing chamber; contacting the substrate with the etchant precursor; and At least a portion of the titanium-containing material is removed.

12. The semiconductor processing method of claim 11 further comprising stopping formation of the plasma of the process precursor prior to flowing the etchant precursor.

13. The semiconductor processing method of claim 11, wherein the etchant precursor comprises thionyl chloride (SOCl2).

14. The semiconductor processing method of claim 11, wherein removing the portion of the titanium-containing material is performed at a temperature of less than or about 400°C.

15. The semiconductor processing method of claim 11, wherein removing the portion of the titanium-containing material is performed at a pressure of less than or about 30 Torr.

16. The semiconductor processing method of claim 11, further comprising a post-treatment performed after removing the portion of the titanium-containing material, wherein the post-treatment comprises exposing the substrate to a plasma comprising one or more of oxygen, hydrogen, or nitrogen.

17. A semiconductor processing method, comprising: flowing an etchant precursor into a processing region of a semiconductor processing chamber, wherein a substrate is received within the processing region, and wherein the substrate defines an exposed region of a titanium-containing material; contacting the substrate with the etchant precursor; removing at least a portion of the titanium-containing material; forming a plasma of a process precursor comprising one or more of oxygen, hydrogen, or nitrogen to produce a process plasma effluent; and The substrate is contacted with the processing plasma effluent.

18. The semiconductor processing method of claim 17, wherein the etchant precursor comprises chlorine.

19. The semiconductor processing method of claim 18, wherein the treating plasma effluents are configured to remove residual chlorine from one or more of the substrate or the semiconductor processing chamber.

20. The semiconductor processing method of claim 17, wherein removing the portion of the titanium-containing material is performed at a temperature of less than or about 380°C and a pressure of less than or about 30 Torr.

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