Systems and methods for titanium-containing film removal

Abstract

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

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of and priority to U.S. Patent Application No. 18 / 101,932, entitled "SYSTEMS AND METHODS FOR TITANIUM-CONTAINING FILM REMOVAL," filed January 26, 2023, which is incorporated herein by reference in its entirety.

[0002] This technology relates to semiconductor processing and devices, and more particularly to selectively etching titanium-containing structures. [Background technology]

[0003] Integrated circuits are realized through processes that form intricately patterned layers of material on a substrate surface. Creating patterned materials on a substrate requires a controlled method for removing exposed material. Chemical etching is used for a variety of purposes, including transferring a photoresist pattern to an underlying layer, thinning a layer, or narrowing the lateral dimensions of features already present on a surface. It is often desirable to have an etching process that etches one material faster than another, for example, to facilitate the pattern transfer process. Such an etching process is said to be selective to the first material. As a result of the diversity of materials, circuits, and processes, etching processes with selectivity to a wide variety of materials have been developed.

[0004] Etching processes can be referred to as wet or dry based on the materials used in the process. For example, wet etching can preferentially remove some oxide dielectrics over other dielectrics and materials. However, wet processes can have difficulty penetrating some constrained trenches and sometimes deform the remaining material. Dry etching, which is performed in a localized plasma formed within the substrate processing region, can penetrate more constrained trenches and is less likely to deform the fragile remaining structures. However, the localized plasma can damage the substrate due to electric arcs that occur when the localized plasma discharges.

[0005] Therefore, there is a need for improved systems and methods that can be used to fabricate high quality devices and structures. The present technology addresses this and other needs. Summary of the Invention

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

[0007] In some embodiments, the etchant precursor may be or may include a halogen-containing precursor. The etchant precursor may be or may include a chlorine-containing precursor. The chlorine-containing precursor may be or may include thionyl chloride (SOCl2). Removing the portion of the titanium-containing material may be performed plasma-free. Removing the portion of the titanium-containing material may be performed at a temperature of about 450° C. or less. Removing the portion of the titanium-containing material may be performed at a pressure of about 0.1 Torr or more. Removing the portion of the titanium-containing material may be performed at a pressure of about 50 Torr or less. The method may include a pretreatment performed before flowing the etchant precursor. The pretreatment may include contacting the substrate with a plasma comprising one or more of oxygen, hydrogen, or nitrogen. The method 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 include a semiconductor processing method. The method may include forming a plasma of a processing precursor including one or more of oxygen, hydrogen, or nitrogen to generate processing plasma effluents. The method may include flowing the processing plasma effluents into a processing region of a semiconductor processing chamber. A substrate may be accommodated in the processing region. The substrate may define an exposed region of titanium-containing material. The method may include contacting the substrate with the processing plasma effluents. The processing plasma effluents may be configured to remove residue from a surface of the titanium-containing material. The method may include flowing an etchant precursor into a substrate processing region of a semiconductor processing chamber. 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.

[0009] In some embodiments, the method may include ceasing formation of a plasma of the treatment precursor before flowing the etchant precursor. The etchant precursor may be or may include thionyl chloride (SOCl). Removing the portion of the titanium-containing material may be performed at a temperature of about 400° C. or less. Removing the portion of the titanium-containing material may be performed at a pressure of about 30 Torr or less. The method 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 including one or more of oxygen, hydrogen, or nitrogen.

[0010] Some embodiments of the present technology may include a semiconductor processing method. The method may include flowing an etchant precursor into a processing region of a semiconductor processing chamber. A substrate may be contained within the processing region. The substrate may define an exposed region of 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. The method may include forming a plasma of a processing precursor comprising one or more of oxygen, hydrogen, or nitrogen to generate processing plasma effluents. The method may include contacting the substrate with the processing plasma effluents.

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

[0012] Such techniques can offer numerous advantages over conventional systems and techniques. For example, the process can enable dry etching that may preserve substrate features. Additionally, the process can selectively remove titanium-containing films relative to other exposed materials on the substrate. These and other embodiments, along with many of these advantages and features, are described in further detail in the following specification and accompanying 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 drawings. [Brief explanation of the drawings]

[0014] [Figure 1] 1 shows a top view of one embodiment of an exemplary processing system according to some embodiments of the present technique. [Figure 2A] 1 is a schematic cross-sectional view of an exemplary semiconductor processing chamber, in accordance with some embodiments of the present technique; [Figure 2B] 2B shows a detailed view of a portion of the processing chamber shown in FIG. 2A, in accordance with some embodiments of the present technique. [Figure 3] FIG. 1 shows a bottom view of an exemplary showerhead in accordance with some embodiments of the present technology. [Figure 4] 1 illustrates exemplary steps in a method according to some embodiments of the present technology. [Figure 5A-B] 1A-1C show schematic cross-sectional views of materials being etched in accordance with some embodiments of the present technique; DETAILED DESCRIPTION OF THE INVENTION

[0015] Some figures have been included as schematics. It should be understood that the drawings are for illustrative purposes and should not be considered to scale unless expressly stated to be to scale. Furthermore, as schematics, the figures are provided to aid in understanding and may not include all aspects or information compared to a realistic depiction, and may include additional or emphasized material for illustrative purposes.

[0016] In the accompanying drawings, similar components and / or features may have the same reference numerals. Furthermore, various components of the same type may be distinguished according to the reference numeral, with a letter distinguishing between the similar components. When only a first reference numeral is used herein, the description may apply to any of the similar components having the same first reference numeral, regardless of the letter.

[0017] In many different semiconductor processes, diluted acids can be used to clean and remove materials from 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 the substrate surface. After the etching or cleaning process is complete, the acid can be dried from the wafer or substrate surface. The use of dilute hydrofluoric acid (DHF) is sometimes referred to as "wet" etching, and the diluent is often water. Additional etching processes can be used that utilize precursors delivered to the substrate. For example, plasma-enhanced processes can also perform dry etching, selectively etching materials by enhancing precursors through a plasma.

[0018] While wet etchants using aqueous solutions or water-based processes can work effectively on certain substrate structures, water can pose challenges in various conditions. For example, utilizing water during an etching process can cause problems when placed on a substrate containing a metallic material. For example, certain subsequent manufacturing processes (e.g., creating gaps, removing oxide dielectrics, or other processes that remove oxygen-containing materials) may be performed after some metallization has formed on the substrate. If water is used in any way during etching, an electrolyte may be generated. When the electrolyte comes into contact with a metallic material, galvanic corrosion may occur between dissimilar metals, and the metal may be corroded or displaced during various processes. In addition, the surface tension of the water diluent can cause pattern deformation and collapse in microstructures. Water-based materials may also be unable to penetrate some high-aspect-ratio features due to surface tension effects. While plasma etching can overcome the issues associated with water-based etching, additional problems may arise. For example, reactive ion etching processes can expose metals to ion activity that can damage structures through bombardment and affect electrical properties.

[0019] The present technology overcomes these problems by implementing a dry etching process that can passivate some materials relative to the material being etched, and in some embodiments, the process can be plasma-free during etching. By utilizing specific precursors that can promote halogen dissociation to provide etchant materials, an etching process can be implemented that can protect surrounding structures. Additionally, the materials and conditions used can enable improved etching over conventional techniques.

[0020] While the remainder of the disclosure will routinely identify particular etching processes utilizing the disclosed technology, it will be readily apparent that the systems and methods are equally applicable to deposition and cleaning processes that may be performed in the described chambers, as well as other etching techniques and other etches that may be performed on various exposed metals that may be maintained or substantially maintained. Correspondingly, the present technology should not be viewed as limited to use with only etching processes or etching chambers. Moreover, while an exemplary chamber is described to provide a foundation for the technology, it should be understood that the technology is applicable to virtually any semiconductor processing chamber capable of performing the steps described.

[0021] 1 illustrates a top view of one embodiment of a deposition, etch, bake, and cure chamber processing system 100, according to an embodiment. In the figure, a pair of front opening unified pods (FOUPs) 102 can supply substrates of various sizes, which are received by a robot arm 104 and placed in a low-pressure holding area 106, and then placed into one of the substrate processing chambers 108a-108f located in tandem sections 109a-109c. A second robot arm 110 can be used to transfer substrate wafers from the holding area 106 to the substrate processing chambers 108a-108f and vice versa. Each substrate processing chamber 108a-108f can be equipped to perform several substrate processing steps, including cyclic layer deposition (CLD), atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), etching, pre-cleaning, degassing, alignment, and other substrate processing, as well as the dry etching processes described herein.

[0022] The substrate processing chambers 108a-108f may include one or more system components for depositing, annealing, curing, and / or etching a dielectric film on a substrate wafer. In one configuration, two pairs of processing chambers (e.g., 108c-108d and 108e-108f) may be used to deposit a dielectric material on a substrate, and a third pair of processing chambers (e.g., 108a-108b) may be used to etch the deposited dielectric. In another configuration, all three pairs of chambers (e.g., 108a-108f) may be configured to etch a dielectric film on a substrate. Any one or more of the processes described may be performed in chambers separate from the fabrication system shown in various embodiments. Of course, additional configurations of dielectric film deposition chambers, etch chambers, annealing chambers, and curing chambers are contemplated for system 100.

[0023] 2A shows a cross-sectional view of an exemplary processing chamber system 200 having separate plasma generation regions within the processing chamber. During etching of a film (e.g., titanium nitride, tantalum nitride, tungsten, silicon, polysilicon, silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, etc.), a process gas can be flowed into a first plasma region 215 through a gas injector assembly 205. A remote plasma system (RPS) 201 can optionally be included in the system and can process a first gas. The first gas then travels through the gas injector assembly 205. The gas injector assembly 205 can include two or more different gas supply channels; if included, a second channel (not shown) can bypass the RPS 201.

[0024] Shown are the cooling plate 203, faceplate 217, ion suppressor 223, showerhead 225, and pedestal 265 or substrate support upon which substrate 255 rests, each of which may be included according to an embodiment. The pedestal 265 may have heat exchange channels through which a heat exchange fluid flows to control the temperature of the substrate. The heat exchange channels may function to heat and / or cool the substrate or wafer during processing. The wafer support platter of the pedestal 265, which may comprise aluminum, ceramic, or a combination thereof, may also be resistively heated and may reach relatively high temperatures (e.g., from about 100° C. to about 1100° C. or higher) using embedded resistive heating elements.

[0025] The face plate 217 may be pyramidal, conical, or another similar structure expanding from a narrow top to a wider base. The face plate 217 may additionally be flat as shown and may include multiple through channels used to distribute process gases. Plasma generating gases and / or plasma excited species may pass through multiple holes in the face plate 217 shown in FIG. 2B for more uniform distribution within the first plasma region 215, in accordance with the use of the RPS 201.

[0026] An exemplary configuration can include gas inlet assembly 205 communicating with gas feed region 258 separated from first plasma region 215 by faceplate 217 such that gases / species flow through holes in faceplate 217 and into first plasma region 215. Structural and operational features can be selected to prevent bulk backflow of plasma from first plasma region 215 back into feed region 258, gas injection assembly 205, and fluid delivery system 210. Faceplate 217 or the conductive top of the chamber and showerhead 225 are shown with an insulating ring 220 positioned between these features, which allows an AC potential to be applied to faceplate 217 relative to showerhead 225 and / or ion suppressor 223. Insulating ring 220 can be positioned between faceplate 217 and showerhead 225 and / or ion suppressor 223, which allows for the formation of a capacitively coupled plasma (CCP) in the first plasma region. Baffles (not shown) may additionally be located within the first plasma region 215 or otherwise coupled to the gas inlet assembly 205 to affect the flow of fluid through the gas inlet assembly 205 and into the plasma region.

[0027] The ion suppressor 223 may include a plate or other shape defining a plurality of apertures throughout its structure. The apertures are configured to suppress the migration of ionic-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 activated gas supply region between the suppressor and the showerhead. In embodiments, the ion suppressor 223 may include a perforated plate with various aperture configurations. The uncharged species may include highly reactive species that are carried through the apertures with a less reactive carrier gas. As described above, migration of ionic species through the apertures can be reduced, and in some cases, completely prevented. Controlling the amount of ionic species passing through the ion suppressor 223 can advantageously provide improved control over the gas mixture contacted with the underlying wafer substrate, which in turn can improve control over the deposition and / or etching characteristics of the gas mixture. For example, adjusting the ion concentration of a gas mixture can significantly alter its etch selectivity. In alternative embodiments where deposition is performed, it is also possible to vary the balance between conformal deposition and flowable style deposition of the dielectric material.

[0028] The plurality of apertures in the ion suppressor 223 may be configured to control the passage of active gas (i.e., ionic species, radical species, and / or neutral species) through the ion suppressor 223. For example, the aspect ratio of the apertures (i.e., diameter to length of the aperture) and / or the geometry of the apertures may be controlled to reduce the flow rate of ionically charged species in the active gas passing through the ion suppressor 223. The apertures in the ion suppressor 223 may include a tapered portion facing the plasma excitation region 215 and a cylindrical portion facing the showerhead 225. The cylindrical portion may be shaped and dimensioned to control the flow rate of ionic species passing to the showerhead 225. As an additional means of controlling the flow rate of ionic species through the ion suppressor 223, an adjustable electrical bias may be applied to the ion suppressor 223.

[0029] The ion suppressor 223 can function to reduce or eliminate the amount of ionic charged species that travel from the plasma generation region to the substrate. Uncharged neutral and radical species can still pass through the apertures in the ion suppressor and react with the substrate. Note that complete elimination of ionically charged species in the reaction region around the substrate may not occur in some embodiments. In certain cases, ionic species are intended to reach the substrate to perform etching and / or deposition processes. In such cases, the ion suppressor can help control the concentration of ionic species in the reaction region to a certain level that is process-supportive.

[0030] The showerhead 225, in combination with the ion suppressor 223, can prevent the plasma present in the first plasma region 215 from directly exciting gases in the substrate processing region 233, but still allow excited species to migrate from the chamber plasma region 215 into the substrate processing region 233. In this manner, the chamber can be configured to prevent the plasma from contacting the substrate 255 being etched. This can advantageously protect various intricate structures and films patterned on the substrate, which could be damaged, misaligned, or otherwise distorted if the generated plasma were to directly contact them. Furthermore, allowing the plasma to contact or approach the substrate level can increase the rate at which oxide species etch. Correspondingly, if the exposed region of material is an oxide, maintaining the plasma away from the substrate can further protect this material.

[0031] The processing system may further include a power supply 240 electrically connected to the processing chamber. The power supply 240 supplies 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 supply an adjustable amount of power to the chamber according to the process being performed. Such a configuration may enable the use of an adjustable plasma in the process being performed. Unlike remote plasma units, which often have an on or off function, an adjustable plasma may be configured to supply a specific amount of power to the plasma region 215. This, in turn, may enable the etching profile formed by the precursor to be enhanced by developing specific plasma characteristics that allow the precursor to dissociate in a specific manner.

[0032] A plasma may be generated in the chamber plasma region 215 above the showerhead 225 or in the substrate processing region 233 below the showerhead 225. A plasma may exist in the chamber plasma region 215, for example, to generate radical precursors from an inflow of a fluorine-containing precursor or other precursor. An AC voltage, typically in the radio frequency ("RF") range, may be applied between a conductive top portion of the processing chamber, such as the faceplate 217, and the showerhead 225 and / or ion suppressor 223 to generate a plasma in the chamber plasma region 215 during deposition. The RF power source may generate a high RF frequency of 13.56 MHz, although other frequencies may be generated alone or in combination with the 13.56 MHz frequency.

[0033] FIG. 2B is a detailed view 253 of features that affect the distribution of process gas through face plate 217. As shown in FIGS. 2A and 2B, the intersection of face plate 217, cooling plate 203, and gas inject assembly 205 defines gas delivery region 258. Gas delivery region 258 may be supplied with process gas from gas inject assembly 205. Gas may fill gas delivery region 258 and flow through apertures 259 in face plate 217 to first plasma region 215. Apertures 259 may be configured to direct flow in a substantially unidirectional manner, which may allow process gas to flow into processing region 233 but partially or completely prevent backflow into gas delivery region 258 after traversing face plate 217.

[0034] A gas distribution assembly such as showerhead 225 used in processing chamber section 200 is also referred to as a dual channel showerhead (DCSH) and is shown in more detail in the embodiment depicted in Figure 3. A dual channel showerhead can accommodate etching processes that allow for separation of etchants outside of processing region 233, limiting their interaction with chamber components and with each other before being delivered into the processing region.

[0035] The showerhead 225 may include an upper plate 214 and a lower plate 216. The plates may be coupled to one another to define a space 218 between the plates. The plates may be coupled to provide a first fluid channel 219 through the upper and lower plates and a second fluid channel 221 through the lower plate 216. The formed channels may be configured to provide fluid access from the space 218 through the lower plate 216 only via the second fluid channel 221, and the first fluid channel 219 may be fluidically isolated from the space 218 between the plates and the second fluid channel 221. The space 218 may be fluidly accessible through one side of the showerhead 225.

[0036] 3 is a bottom view of a showerhead 325 for use in a processing chamber, according to an embodiment. The showerhead 325 may correspond to the showerhead 225 shown in FIG. 2A. The through-holes 365, which represent the first fluid channels 219, may have multiple shapes and configurations to control and influence the flow rate of precursors through the showerhead 225. The small holes 375, which represent the second fluid channels 221, may provide a more uniform distribution across the surface of the showerhead, even among the through-holes 365, which may help to mix the precursors more uniformly as they exit the showerhead than other configurations.

[0037] The chambers described above can be used in performing exemplary methods, including etching methods. Referring to FIG. 4 , exemplary steps of a method 400 according to an embodiment of the present technology are shown. The method 400 can include one or more steps prior to the start of the method, including front-end processing, deposition, gate formation, etching, polishing, cleaning, or any other steps that may be performed before the described steps. The method can also include several optional steps, which may or may not be specifically associated with certain embodiments of the method according to the present technology. For example, many of the steps are described to provide a broader scope of processes that may be performed, but are not critical to the present technology or may be performed by alternative methods, as discussed further below. The method 400 can describe the steps shown generally in FIGS. 5A-5B, which will be described in conjunction with the steps of the method 400. It should be understood that the figures are only partial schematic views, and that the substrate may include several additional materials and features with various properties and aspects as shown in the figures.

[0038] Method 400 may or may not include optional steps for developing the semiconductor structure for a particular fabrication process. It should be understood that method 400 can be performed on several semiconductor structures, including the exemplary structure in which a nitride removal process may be performed, or on the substrate 505 shown in FIG. 5A . 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 that may form the recess, trench, via, or isolation structure. The exposed material at any time during the etching process may be or include metal material, such as for gates, dielectric material, contact material, 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, such as a tungsten-containing material, that extends into the substrate 505. An aluminum-containing material 515 may cover a portion of the substrate 505. A low-k material 520, such as silicon oxide, may extend from the aluminum-containing material 515. A titanium-containing material 525, such as titanium nitride, may be present on the low-k material 520. As shown in Figure 5A, the titanium-containing material 525 may be exposed to one or more other materials, including metal-containing materials, dielectrics including silicon oxide, or some other semiconductor material from which the titanium-containing material is to be removed, such as an oxide of aluminum, and any other material.

[0039] The structures of interest are not intended to be limiting, and it should be understood that any of a variety of other semiconductor structures containing titanium-containing materials are similarly encompassed. Because 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 of the other materials described elsewhere, other exemplary structures can include two-dimensional and three-dimensional structures common in semiconductor manufacturing, in which titanium-containing materials, such as titanium nitride, are removed relative to one or more other materials. In addition, while high aspect ratio structures can benefit from the present technique, the technique may be applicable to lower aspect ratios and any other structures as well.

[0040] For example, while layers of material according to the present technology can be characterized by any aspect ratio, i.e., height-to-width ratio, of the structure, in some embodiments, the material can be characterized by a larger aspect ratio that may not allow for sufficient etching using conventional techniques or methodologies. For example, in some embodiments, the aspect ratio of any layer of an exemplary structure may be about 10:1 or greater, about 20:1 or greater, about 30:1 or greater, about 40:1 or greater, about 50:1 or greater, or even greater. Additionally, each layer can be characterized by a reduced width or thickness of about 100 nm or less, about 80 nm or less, about 60 nm or less, about 50 nm or less, about 40 nm or less, about 30 nm or less, about 20 nm or less, about 10 nm or less, about 5 nm or less, about 1 nm or less, or less, including any fractional part of any of the aforementioned values, such as 20.5 nm, 1.5 nm, etc. This combination of high aspect ratio and minimal thickness can prevent many conventional etching processes or can require substantially longer etching times to remove layers at limited widths along vertical or horizontal distances. Additionally, damage to or removal of other exposed layers can occur with conventional techniques.

[0041] While method 400 can be performed to remove exposed titanium-containing material in some embodiments, embodiments of the present technology may remove some nitride or titanium-containing material in some structures. The method can include specific steps for removing the titanium-containing material and can include one or more optional steps for preparing or processing the titanium-containing material. For example, in the exemplary substrate structure, residues from previous processing may be present on the film, such as titanium nitride, that must be removed. For example, residual photoresist or by-products from previous processing may be present on the titanium nitride layer. These materials may block access to the titanium nitride or may interact with etchants differently than a clean titanium nitride surface, thereby impeding one or more aspects of the etching. Accordingly, in some embodiments, optional pretreatment of the titanium-containing film or titanium-containing material may be performed in optional step 405. Exemplary pretreatment steps may include, for example, thermal treatment, wet treatment, or plasma treatment, and these processes may be performed in chamber 200 and in several chambers that may be included on system 100 described above.

[0042] In one exemplary plasma process, a remote or local plasma can be generated in one or more ways from a precursor intended to interact with the residue. For example, a chamber such as chamber 200 described above can be utilized to generate either a remote or local plasma 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 the remote plasma region or into the processing region, where the plasma can strike. Plasma effluents can be flowed toward the substrate to contact the residue material. The plasma process can be physical or chemical, depending on the material to be removed to expose the titanium-containing material. For example, plasma effluents can be flowed to contact the residue and physically remove it, such as by a sputtering process, or precursors can be flowed to interact with the residue to generate volatile by-products, which can then be removed from the chamber.

[0043] Exemplary precursors used in pretreatment may be or include hydrogen, hydrocarbons, water vapor, alcohols, hydrogen peroxide, or other materials that may contain hydrogen, as would be understood by one skilled in the art. Exemplary oxygen-containing precursors may include molecular oxygen, ozone, nitrous oxide, nitric oxide, or other oxygen-containing materials. Nitrogen gas may also be used to remove certain residues, or combination precursors having one or more of hydrogen, oxygen, and / or nitrogen may be utilized. Once the residues or by-products are removed, a clean titanium nitride surface can be exposed for etching. Although the halogen-containing precursor can be flowed through a remote plasma region of the processing chamber, such as region 215 described above, in some embodiments, method 400 may not utilize plasma effluents during the etching process. For example, method 400 can flow a fluorine-containing or other halogen-containing precursor to a substrate without exposing the precursor to a plasma and still remove titanium-containing materials without generating plasma effluents. In some embodiments, the halogen-containing precursor can be plasma-enhanced, which can be performed in a remote plasma region to prevent contact between the material on the substrate and the plasma effluents. The halogen-containing precursor can contact a semiconductor substrate containing exposed titanium-containing material and further generate fluorinated materials, such as titanium fluoride or titanium halide materials, that may remain on the semiconductor substrate. In some embodiments, the halogen-containing precursor can donate 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.

[0044] Method 400 may include, in step 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 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 process. For example, method 400 may flow the etchant precursor to the substrate without exposing the precursor to a plasma and removing titanium-containing material without generating plasma effluents. In some embodiments, the etchant precursor may be plasma-enhanced, which may be performed in a remote plasma region to prevent contact between materials on the substrate and plasma effluents. The etchant precursor may contact a semiconductor substrate containing exposed regions of titanium-containing material and may generate chlorinated materials, such as titanium chloride fluoride or titanium halide materials, that may remain on the semiconductor substrate or may volatilize. In some embodiments, the halogen-containing precursor may donate one or more chlorine atoms while accepting one or more nitrogen atoms. Some halogen-containing precursors, such as plasma-enhanced precursors, may provide chlorine radicals while other plasma radicals may accept nitrogen from the film. Correspondingly, in step 415, the etchant precursor may etch or remove the titanium-containing material, as shown in FIG. 5B.

[0045] As described above, the present technique can be performed without generating a plasma during the etching steps 410-415. Plasma-free removal can be achieved by utilizing certain precursors and performing the etching within certain process conditions, and the removal can also be a dry etch. Thus, techniques according to aspects of the present technique can be performed to remove titanium nitride from narrow features, as well as high aspect ratio features and thin dimensions, where wet etching may be unsuitable. Optional steps can be performed to remove residue from the substrate or chamber, and can include post-treatment in optional step 420. Post-treatment can include steps similar to pre-treatment and can include any of the precursors or steps described above for pre-treatment. In some embodiments, post-treatment can remove residual etchant, such as chlorine, from the substrate or chamber. While pre-treatment and / or post-treatment steps can include generating a plasma and delivering plasma effluents to the substrate, it should be understood that a plasma need not be formed during the etching steps 410-415. For example, in some embodiments, a plasma need not be generated while etchant precursors are delivered into the processing chamber.

[0046] The etchant precursors during the etching steps 410-415 can include halogen-containing precursors, and in some embodiments, can include one or more of fluorine or chlorine. The specific precursor can be based on the bonding or stability of the precursor. Exemplary etchant precursors can include halogen-containing precursors, such as thionyl chloride (SOCl2), and other chlorine- or fluorine-containing precursors. The etchant can also be flowed 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 can optionally be delivered to the remote plasma region and plasma-enhanced before being flowed into the processing region. In embodiments, the etchant precursor can be provided with a hydrogen-containing precursor, such as molecular hydrogen (H2). The etchant precursor can also be delivered with a carrier gas, which can include nitrogen, helium, argon, or other rare, inert, or useful precursors. The carrier gas serves to dilute the etchant precursor, thereby controlling the etch rate and dispersing the etchant precursor.

[0047] As a non-limiting example, thionyl chloride (SOCl) can easily donate one or two chlorine atoms and one oxygen atom at high temperatures and can accept one nitrogen atom from, for example, titanium nitride, and can be maintained in the gas phase. Correspondingly, titanium-containing materials can be generated as reaction by-products, which can be gas molecules and can be vented or removed from the processing chamber. For example, chlorine from the etchant precursor can combine with titanium nitride to form titanium tetrachloride (TiCl), titanium(III) chloride (TiCl), or titanium oxychloride (TiOCl). Correspondingly, nitrogen-containing materials can be generated as reaction by-products, which can be gas molecules and can be vented or removed from the processing chamber. For example, nitrogen from titanium nitride can form stable by-products such as diatomic nitrogen (N), nitrous oxide (N2O), and nitrogen dioxide (NO2). Furthermore, sulfur-containing materials can be generated as reaction by-products, which can be gas molecules and can be vented or removed from the processing chamber. For example, residual sulfur from the etchant precursor may exist as sulfur dioxide (SO), sulfur monoxide (SO), or sulfur dichloride (S2Cl22). Thus, the present process is configured to exchange chlorine and nitrogen between the etchant precursor and exposed regions of the titanium nitride, thereby removing the titanium nitride under processing conditions that may produce volatile by-products. Due to the controlled delivery and processing described above, the chlorine-containing material can easily remove the titanium nitride while being unable to etch or only interacting minimally with other exposed surfaces, which may result in improved selectivity over conventional techniques.

[0048] According to the present technology, etching can be influenced and accelerated by process conditions. Because the etching reaction can proceed based on thermal dissociation of halogens from the etchant precursor, the temperature can depend, at least in part, on the specific halogen and / or other atoms in the etchant precursor to initiate dissociation. For example, as the temperature increases above about 250°C, etching begins to occur or increase, which can indicate activation of precursor dissociation and / or reaction with titanium nitride. As the temperature continues to increase, dissociation, as well as reaction with titanium nitride, can be further accelerated.

[0049] Correspondingly, in some embodiments of the present technique, the etching method can be performed at substrate, pedestal, and / or chamber temperatures of about 450°C or less, and can be performed at temperatures of about 440°C or less, about 430°C or less, about 420°C or less, about 410°C or less, about 400°C or less, about 390°C or less, about 380°C or less, about 370°C or less, about 360°C or less, about 350°C or less, or lower. The temperature can also be maintained within these ranges, narrower ranges encompassed by these ranges, or any temperature between any of these ranges. In some embodiments, the method can be performed on a substrate that may have several created features, which may result in a thermal budget. In embodiments, higher temperatures can increase etching of the titanium-containing material 425. Correspondingly, in some embodiments, the method can be carried out at a temperature of about 300°C or greater, and can also be carried out at a temperature of about 310°C or greater, about 320°C or greater, about 330°C or greater, about 340°C or greater, about 350°C or greater, about 360°C or greater, or even higher.

[0050] When thionyl chloride (SOCl) is used as the etchant precursor, the pressure within the chamber can also affect the process performed and can affect when the etchant precursor may dissociate, for example, when sulfur, oxygen, and chlorine may dissociate. Correspondingly, in some embodiments, the pressure can be maintained at about 0.5 Torr or greater, about 1 Torr or greater, about 2 Torr or greater, about 3 Torr or greater, about 4 Torr or greater, about 5 Torr or greater, about 6 Torr or greater, about 7 Torr or greater, about 8 Torr or greater, about 9 Torr or greater, about 10 Torr or greater, about 15 Torr or greater, about 20 Torr or greater, about 25 Torr or greater, about 30 Torr or greater, or greater. Correspondingly, the pressure may be maintained at or below about 50 Torr, about 40 Torr, about 30 Torr, about 25 Torr, about 20 Torr, about 15 Torr, about 10 Torr, about 9 Torr, about 8 Torr, about 7 Torr, about 6 Torr, about 5 Torr, about 4 Torr, about 3 Torr, about 2 Torr, about 1 Torr, or about 0.1 Torr. The pressure may also be maintained within these ranges, narrower ranges encompassed by these ranges, or any pressure between any of these ranges. In some embodiments, as the pressure increases above about 0.5 Torr, the amount of etching may be accelerated and initiated. Additionally, as the pressure continues to increase, etching may improve to a point before beginning to decrease and eventually stopping as the pressure continues to increase.

[0051] Without being bound by any particular theory, the pressure within the chamber can affect processing with the precursors described above. Low pressure can reduce flow across the substrate, which can likewise reduce dissociation. As pressure increases, interaction between the etchant precursor and the substrate can increase, which can increase the reaction and etching rate. However, as pressure continues to increase, recombination of dissociated etchant precursor atoms can increase due to the relative stability of the molecules. Thus, the precursor can be efficiently pumped back out of the chamber without reacting with the substrate. Additionally, as pressure continues to increase, interaction with the titanium nitride surface can be suppressed, or by-product titanium chloride can be reintroduced into the film being etched, further limiting removal. Correspondingly, in some embodiments, the pressure within the processing chamber can be maintained at or below about 30 Torr.

[0052] The flow rate of the etchant precursor can be adjusted (even in situ) to control the etching process. For example, the flow rate of the etchant precursor can be reduced, maintained, or increased during the removal step. Increasing the flow rate of the etchant precursor can increase the etch rate up to a saturation point. During any step of method 400, the flow rate of the etchant precursor can be from about 5 sccm to about 1,000 sccm. Additionally, the flow rate of the etchant precursor can be maintained at or below about 900 sccm, about 800 sccm, about 700 sccm, about 600 sccm, about 500 sccm, about 400 sccm, about 300 sccm, about 200 sccm, about 100 sccm, or lower. The flow rate can also be between any of these aforementioned flow rates or within a smaller range encompassed by any of the above values.

[0053] To add further control to the etching process, the etchant precursor can be pulsed in some embodiments, and can be continuously or in a series of pulses throughout the etching process, which can be constant or vary over time. Pulsed delivery can be characterized by a first period during which the etchant precursor is flowed and a second period during which the etchant precursor is paused or stopped. In some embodiments, a purge gas can be flowed during the second period. The purge gas can be or include nitrogen, helium, argon, or other rare, inert, or useful purge gas. The durations of any pulse steps can be similar to or different from each other, with one period being longer than the other. In embodiments, the period or continuous flow of precursor may be carried out for a period of about 1 second or greater, and may also be carried out for a period of about 2 seconds or greater, about 3 seconds or greater, about 4 seconds or greater, about 5 seconds or greater, about 6 seconds or greater, about 7 seconds or greater, about 8 seconds or greater, about 9 seconds or greater, about 10 seconds or greater, about 11 seconds or greater, about 12 seconds or greater, about 13 seconds or greater, about 14 seconds or greater, about 15 seconds or greater, about 20 seconds or greater, about 30 seconds or greater, about 45 seconds or greater, about 60 seconds or greater, or longer. The time may also be any smaller range encompassed within any of these ranges. For example, in some embodiments, the period or continuous flow of precursor may be carried out for a period of about 60 seconds or less, and may also be carried out for a period of about 45 seconds or less, about 30 seconds or less, about 20 seconds or less, about 15 seconds or less, about 10 seconds or less, about 5 seconds or less, about 4 seconds or less, about 3 seconds or less, about 2 seconds or less, about 1 second or less, about 0.5 seconds or less, about 0.1 seconds or less, or even shorter. In some embodiments, the etch rate may increase as the precursor delivery is carried out for a longer period of time.

[0054] By performing processes 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 metals, dielectrics, including silicon-containing materials, including silicon oxide, or other materials. Embodiments of the present technology can etch titanium nitride at a rate of at least about 2:1 relative to either silicon oxide or other materials, and can also etch titanium nitride relative to silicon oxide or other materials of interest at selectivities of about 3:1 or greater, about 4:1 or greater, about 5:1 or greater, about 6:1 or greater, about 7:1 or greater, about 8:1 or greater, about 9:1 or greater, about 10:1 or greater, about 15:1 or greater, about 20:1 or greater, about 25:1 or greater, about 30:1 or greater, about 35:1 or greater, about 40:1 or greater, about 45:1 or greater, about 50:1 or greater, or even higher. For example, etches performed in accordance with some embodiments of the present technology can etch titanium nitride while substantially or essentially preserving materials such as silicon oxide or other materials (e.g., nitrides or oxides of silicon, aluminum, or hafnium), metals such as tungsten or molybdenum, or polysilicon.

[0055] The selectivity may be based in part on the precursors used and their ability to dissociate over a more controlled temperature range. Conventional dry etchants may not be able to produce the etch selectivity of embodiments of the present technology. Similarly, because wet etchants readily remove silicon oxide, wet etchants may also not be able to selectively etch at rates comparable to embodiments of the present technology.

[0056] The above-described method can enable the removal of titanium-containing materials relative to some other exposed material. Utilizing an etchant at the operating conditions described above can result in improved etching of titanium nitride, which can increase selectivity over conventional techniques and improve etch access in small pitch features.

[0057] In the foregoing specification, for purposes of explanation, numerous details are set forth in order to facilitate an understanding of various embodiments of the present technology. However, it will be apparent to one skilled in the art that particular embodiments may be practiced without some of these details or with additional details.

[0058] Although several embodiments have been disclosed, those skilled in the art will recognize that various modifications, alternative configurations, and equivalents may be used without departing from the spirit of the embodiments. Additionally, some well-known processes and elements have not been described to avoid unnecessarily obscuring the present technology. Therefore, the foregoing description should not be construed as limiting the scope of the present technology. In addition, while a method or process may be described as sequential or stepwise, it should be understood that these steps may be performed simultaneously or in a different order than described.

[0059] Where a range of values ​​is given, unless the context clearly indicates otherwise, it is understood that each intervening value between the upper and lower limit of that range is specifically disclosed, to the smallest unit of the lower limit. Any narrower range between any stated or unstated intervening value in a stated range and any other stated or intervening value within that stated range is encompassed. The upper and lower limits of these narrower ranges may individually be included or excluded within the range, and each range where one or both limits are included or neither are included within the narrower range is also encompassed within the technology, subject to any specifically excluded limits in the stated range. When a stated range includes one or both limits, ranges excluding one or both of those included limits are also included.

[0060] As used in this specification and 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 a plurality of such precursors, reference to "the material" includes a reference to one or more materials and equivalents known to those skilled in the art, and so forth.

[0061] Furthermore, the terms "comprise(s)", "comprising", "contain(s)", "containing", "include(s)", and "including", when used in this specification and claims, are intended to specify the presence of stated features, integers, components, or steps, but do not exclude the presence or addition of one or more other features, integers, components, steps, actions, or groups.

Claims

1. 1. A semiconductor processing method comprising: flowing an etchant precursor into a processing region of a semiconductor processing chamber, wherein a substrate is contained within the processing region, the substrate defining an exposed region of titanium-containing material; contacting the substrate with the etchant precursor; removing at least a portion of the titanium-containing material; A semiconductor processing method comprising:

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

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

4. The chlorine-containing precursor is thionyl chloride (SOCl ２ 4. The semiconductor processing method of claim 3, comprising:

5. The semiconductor processing method of claim 1 , wherein removing said portion of said titanium-containing material is performed plasma-free.

6. 10. The semiconductor processing method of claim 1, wherein removing said portion of said titanium-containing material is performed at a temperature of about 450[deg.] C. or less.

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

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

9. 10. The semiconductor processing method of claim 1, further comprising a pre-treatment occurring before flowing the etchant precursor, the pre-treatment comprising contacting the substrate with a plasma comprising one or more of oxygen, hydrogen, or nitrogen.

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

11. 1. A semiconductor processing method comprising: forming a plasma of a treatment precursor comprising one or more of oxygen, hydrogen, or nitrogen to generate treatment plasma effluents; flowing the processing plasma effluents into a processing region of a semiconductor processing chamber, a substrate contained within the processing region, the substrate defining an exposed region of titanium-containing material; contacting the substrate with the treatment plasma effluents, the treatment plasma effluents 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; removing at least a portion of the titanium-containing material; A semiconductor processing method comprising:

12. 12. The semiconductor processing method of claim 11, further comprising ceasing formation of the plasma of the process precursor before flowing the etchant precursor.

13. The etchant precursor is thionyl chloride (SOCl ２ 12. The semiconductor processing method of claim 11, comprising:

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

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

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

17. 1. A semiconductor processing method comprising: flowing an etchant precursor into a processing region of a semiconductor processing chamber, wherein a substrate is contained within the processing region, the substrate defining an exposed region of 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 treatment precursor comprising one or more of oxygen, hydrogen, or nitrogen to generate treatment plasma effluents; contacting the substrate with the treatment plasma effluent; A semiconductor processing method comprising:

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

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

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

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