Systems and methods for aluminum-containing film removal

Abstract

An exemplary etching method may include flowing a halogen-containing precursor into a substrate processing region of a semiconductor processing chamber. The halogen-containing precursor may be characterized by a gas density of about 5 g / L or greater. The method may include contacting a substrate contained within the substrate processing region with the halogen-containing precursor. The substrate may define exposed regions of aluminum-containing material. The contacting may produce an aluminum halide material. The method may include flowing an etchant precursor into the substrate processing region. The method may include contacting the aluminum halide material with the etchant precursor. The method may include removing the aluminum halide material.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Patent Application No. 17 / 018,229, entitled "SYSTEMS AND METHODS FOR ALUMINUM-CONTAINING FILM REMOVAL," filed September 11, 2020, which is incorporated herein by reference in its entirety. [Technical Field]

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

[0003] Integrated circuits are made possible by processes that create 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. Due to the diversity of materials, circuits, and processes, etching processes have been developed that are selective to a variety of materials.

[0004] Etching processes can be referred to as wet or dry based on the materials used in the process. For example, wet etching may preferentially remove some oxide dielectrics over other dielectrics and materials. However, wet processes can have difficulty penetrating some constrained trenches and can 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 may be 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 these and other needs. Summary of the Invention

[0006] An exemplary etching method may include flowing a halogen-containing precursor into a substrate processing region of a semiconductor processing chamber. The halogen-containing precursor may be characterized by a gas density of about 5 g / L or greater. The method may include contacting a substrate contained within the substrate processing region with the halogen-containing precursor. The substrate may define exposed regions of aluminum-containing material. The contacting may produce an aluminum halide material. The method may include flowing an etchant precursor into the substrate processing region. The method may include contacting the aluminum halide material with the etchant precursor. The method may include removing the aluminum halide material.

[0007] In some embodiments, the halogen-containing precursor can include a transition metal, and the etchant precursor can be or include a chlorine-containing precursor. The halogen-containing precursor can include tungsten or niobium. The aluminum-containing material can be or include aluminum oxide. The etching method can be a plasma-free etching process. The etching method can be performed at a temperature of about 300° C. or greater. The etching method can be performed at a pressure of about 0.1 Torr or greater. The etching method can be performed at a pressure of about 50 Torr or less. The method can include a pretreatment performed before flowing the halogen-containing precursor. The pretreatment can include contacting the substrate with a plasma including one or more of oxygen, hydrogen, or nitrogen. The method can include a post-treatment performed after the etching method. The post-treatment can include contacting the substrate with a plasma including one or more of oxygen, hydrogen, or nitrogen.

[0008] Some embodiments of the present technology may include an etching method. The method may include forming a plasma of a process precursor including one or more of oxygen, hydrogen, or nitrogen to generate process plasma effluents. The method may include flowing the process plasma effluents into a substrate processing region of a semiconductor processing chamber. The method may include contacting the process plasma effluents with a substrate contained in the substrate processing region. The substrate may define an exposed region of aluminum-containing material. The process plasma effluents may be configured to remove residue from a surface of the aluminum-containing material. The method may include flowing a first halogen-containing precursor into the substrate processing region of the semiconductor processing chamber. The method may include contacting the substrate with the first halogen-containing precursor. The method may include flowing a second halogen-containing precursor into the substrate processing region of the semiconductor processing chamber. The method may include removing the aluminum-containing material.

[0009] In some embodiments, the first halogen-containing material may comprise a plasma effluent of a tungsten- or niobium- or fluorine-containing precursor. The second halogen-containing precursor may be or comprise boron trichloride. The method may include terminating formation of the plasma before flowing the first halogen-containing material. The etching method may be performed at a temperature of about 300° C. or greater. The etching method may be performed at a pressure of about 0.1 Torr or greater. The method may include a post-treatment performed after the etching method. The post-treatment 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 an etching method. The method may include flowing a fluorine-containing precursor into a substrate processing region of a semiconductor processing chamber. The fluorine-containing precursor may be characterized by a gas density of about 5 g / L or greater. The method may include contacting a substrate contained in the substrate processing region with the fluorine-containing precursor. The substrate may define an exposed region of aluminum-containing material. The method may include flowing a chlorine-containing precursor into the substrate processing region of the semiconductor processing chamber. The method may include contacting the substrate with the chlorine-containing precursor. The method may include removing the aluminum-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 fluorine-containing precursor can include tungsten or niobium, and the chlorine-containing precursor can include boron. The treatment plasma effluent can be configured to remove residual tungsten or niobium from one or more of the substrate or the semiconductor processing chamber. The etching method can be performed at a temperature of about 300° C. or greater and a pressure of about 0.1 Torr or greater.

[0012] Such techniques may offer numerous advantages over conventional systems and techniques. For example, the process may allow for dry etching that may preserve substrate features. Additionally, the process may selectively remove aluminum-containing films relative to other exposed materials on the substrate. These and other embodiments, as well as many of their advantages and features, are described in more detail in the following specification and in conjunction with the 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 shows a schematic cross-sectional view of an exemplary processing chamber according to 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 an embodiment of the present technology. [Figure 5A-B] 1 shows a schematic cross-sectional view of a material being etched, according to an embodiment of the present technique; DETAILED DESCRIPTION OF THE INVENTION

[0015] Some of the figures are included as schematic diagrams. It is understood that the figures are for illustrative purposes and should not be considered to scale unless expressly stated otherwise. Furthermore, as schematic diagrams, the figures are provided to aid in understanding and may not include all aspects or information compared to realistic depictions 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 by a letter following the reference numeral that distinguishes between the similar components. When only a first reference numeral is used in this specification, the description may apply to any similar component having the same first reference numeral, whatever its letter.

[0017] In many different semiconductor processes, diluted acids can be used to clean substrates and remove materials from them. For example, dilute hydrofluoric acid can be an effective etchant for silicon oxide, aluminum oxide, and other materials and can be used to remove materials from substrate surfaces. 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 by selectively etching materials by enhancing precursors through the 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 metallic materials. For example, certain subsequent manufacturing processes (e.g., gap creation, oxide dielectric removal, 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 the metallic material, galvanic corrosion may occur between the 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 distortion and collapse in the microstructure. Water-based materials may also be unable to penetrate some high-aspect-ratio features due to surface tension effects.

[0019] Although plasma etching can overcome the problems associated with water-based etching, additional issues can arise. For example, aluminum oxide and other aluminum-based dielectrics are incorporated into many semiconductor structures and exhibit dielectric properties. Due to their dielectric nature, these aluminum materials do not readily conduct electricity. Correspondingly, when charged plasma species are directed toward these materials, charge buildup can occur along the surfaces of aluminum-based dielectrics. Once the buildup exceeds a threshold, voltages can cause breakdown, which can damage the aluminum material.

[0020] 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. In addition, the materials and conditions used can enable improved etching over conventional techniques.

[0021] 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, including intermediate and back-end-of-line processes, and other etching techniques that may be performed on various exposed metals that may be preserved or substantially preserved. 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.

[0022] 1 illustrates a top view of one embodiment of a processing system 100 with deposition, etch, bake, and cure chambers, 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, orientation, and other substrate processing, as well as the dry etching processes described herein.

[0023] 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.

[0024] 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, and a second channel (not shown), if included, can bypass the RPS 201.

[0025] 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 operate 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. or less to about 1100° C. or more) using embedded resistive heating elements.

[0026] The face plate 217 may be pyramidal, conical, or other similar structure, narrow at the top and widening toward the bottom. 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, shown in FIG. 2B , in the face plate 217, in accordance with the use of the RPS 201, and may be more uniformly distributed within the first plasma region 215.

[0027] An exemplary configuration can include gas inject assembly 205 communicating with gas feed region 258 separated from first plasma region 215 by faceplate 217 such that the above 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 inject assembly 205, and fluid delivery system 210. Faceplate 217 or the conductive top of the chamber and showerhead 225 are shown with insulating ring 220 positioned between those 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.

[0028] The ion suppressor 223 may include a plate or other shape defining a plurality of apertures throughout its structure, configured to suppress the migration of ionically charged species exiting 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 be or 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 may be reduced, and in some cases, completely prevented. Controlling the amount of ionic species that pass through the ion suppressor 223 can advantageously provide improved control over the gas mixture contacted with the underlying wafer substrate, which in turn may provide improved control over the deposition and / or etching characteristics of the gas mixture. For example, adjusting the ion concentration of the gas mixture can significantly change the etch selectivity of the gas mixture, e.g., SiNx:SiOx etch ratio, Si:SiOx etch ratio, etc. In alternative embodiments where deposition is performed, it is also possible to vary the balance between conformal and flowable style deposition of the dielectric material.

[0029] 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.

[0030] The ion suppressor 223 may 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 may still pass through the apertures in the ion suppressor and react with the substrate. Note that complete removal of ionically charged species in the reaction region around the substrate may not be achieved 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 may help control the concentration of ionic species in the reaction region to support the process at a constant level.

[0031] 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, while still allowing 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 of etching performed by oxide species. Correspondingly, if the exposed area of ​​material is an oxide, maintaining the plasma away from the substrate can further protect this material.

[0032] 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 processing region 233. The power supply may be configured to deliver 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 deliver a specific amount of power to the first 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.

[0033] A plasma can be ignited either in the chamber plasma region 215 above the showerhead 225 or in the substrate processing region 233 below the showerhead 225. A plasma can 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, can 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 ignite a plasma in the chamber plasma region 215 during deposition. The RF power source can generate a high RF frequency of 13.56 MHz, although other frequencies can also be generated alone or in combination with the 13.56 MHz frequency.

[0034] 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 single direction. This may allow process gas to flow into processing region 233 but may partially or completely prevent backflow into gas delivery region 258 after traversing face plate 217.

[0035] A gas distribution assembly, such as the showerhead 225, for use in the processing chamber system 200 may be referred to as a dual channel showerhead (DCSH), and is further detailed in the embodiment illustrated in Figure 3. A dual channel showerhead may provide an etching process that allows for separation of etchants outside of the processing region 233, resulting in limited interaction of the etchants with chamber components and with each other before being delivered into the processing region.

[0036] The showerhead 225 may include an upper plate 214 and a lower plate 216. The plates may be coupled together 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 a side of the showerhead 225.

[0037] 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. Small holes 375, which represent the second fluid channels 221, may be more evenly distributed across the surface of the showerhead, even among the through-holes 365, which may help mix the precursors more uniformly as they exit the showerhead than other configurations.

[0038] 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 can include any number of additional materials and features having various properties and aspects as shown in the figures.

[0039] Method 400 may or may not include optional steps for developing the semiconductor structure into a particular fabrication step. It should be understood that method 400 can be performed on any number of semiconductor structures or substrates 505 shown in FIG. 5A , including the exemplary structure that may undergo an oxide removal step. 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 insulating structure. The exposed material at any time during the etching process may be or include metal material, dielectric material, contact material, transistor material, or any other material that may be used in semiconductor processing, such as for gates. In some embodiments, the exemplary substrate may include an aluminum-containing material 515, such as aluminum oxide, or some other aluminum-containing dielectric. The aluminum-containing material can be exposed to one or more other materials 510, including any of a metal, other dielectrics including silicon oxide or silicon nitride, or some other semiconductor material against which the aluminum-containing material is to be removed, such as a nitride of titanium, tantalum, or other material.

[0040] 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 aluminum-containing materials are equally encompassed. Because the present technique can selectively remove aluminum-containing materials relative to other exposed materials, such as silicon-containing materials, 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 aluminum-containing materials, such as aluminum oxide, 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.

[0041] For example, layers of material 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 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 can 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 greater. Additionally, each layer can be characterized by a reduced width or thickness of less than about 100 nm, less than about 80 nm, less than about 60 nm, less than about 50 nm, less than about 40 nm, less than about 30 nm, less than about 20 nm, less than about 10 nm, less than about 5 nm, less than about 1 nm, 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 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.

[0042] While method 400 can be performed in embodiments to remove exposed aluminum-containing material, embodiments of the present technology can remove any number of oxides or aluminum-containing materials in any number of structures. The method can include specific steps for removing aluminum-containing materials and can include one or more optional steps for preparing or treating the aluminum-containing material. For example, in the exemplary substrate structure, residues from previous processes can be present on the film to be removed, such as aluminum oxide. For example, residual photoresist or by-products from previous processes can be present on the aluminum oxide layer. These materials can block access to the aluminum oxide or can interact with etchants differently than a clean aluminum oxide surface, which can impede one or more aspects of the etching. Accordingly, in some embodiments, optional pretreatment of the aluminum-containing film or aluminum-containing material can be performed in optional step 405. Exemplary pretreatment steps can include, for example, thermal treatments, wet treatments, or plasma treatments, and these processes can be performed in chamber 200 and any number of chambers that can be included on system 100 described above.

[0043] In one exemplary plasma process, a remote plasma or a 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 used to generate either a remote plasma or a 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. The plasma effluent can be flowed to the substrate and contact the residue material. The plasma process can be physical or chemical, depending on the material to be removed to expose the aluminum-containing material. For example, the plasma effluent can be flowed to contact and physically remove the residue, such as by a sputtering process, or a precursor can be flowed to interact with the residue and generate volatile by-products that can be removed from the chamber.

[0044] 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 aluminum oxide surface may be exposed for etching.

[0045] Method 400 may include, in step 410, flowing a halogen-containing precursor, including a first halogen-containing precursor, into a substrate processing region of a semiconductor processing chamber housing the substrate described or some other substrate. 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 process. For example, method 400 may flow a fluorine-containing or other halogen-containing precursor to a substrate without exposing the precursor to a plasma and removing aluminum-containing materials without generating plasma effluents. In some embodiments, the halogen-containing precursor may be plasma-enhanced, which may be performed in a remote plasma region to prevent material on the substrate from contacting plasma effluents. The halogen-containing precursor may contact a semiconductor substrate containing exposed aluminum-containing material and may generate fluorinated materials, such as aluminum fluoride or aluminum halide materials, that may remain on the semiconductor substrate. In some embodiments, the halogen-containing precursor may 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.

[0046] Following the fluorination step, an etchant precursor can be flowed into the processing region in step 415. In some embodiments, the etchant precursor can be a second halogen-containing precursor, which can contain the same or a different halogen as the first halogen-containing precursor. The etchant precursor can be further exchanged to generate aluminum by-products that may be volatile under processing conditions and that may be evolved from the substrate. Correspondingly, in step 420, the etchant precursor can etch or remove aluminum material, as shown in FIG. 5B.

[0047] As described above, the present technique can be performed without generating a plasma during the etching steps 410-420. By utilizing certain precursors and performing the etching within certain process conditions, plasma-free removal can be achieved, and the removal can also be a dry etch. Correspondingly, techniques according to aspects of the present technique can be performed to remove aluminum oxide from narrow features, as well as high aspect ratio features and thin dimensions, which may be unsuitable for wet etching. Optional steps may be performed to remove residue from the substrate or chamber, including post-treatment in optional step 425. Post-treatment may include steps similar to pre-treatment and may include any of the precursors or steps described above for pre-treatment. In some embodiments, post-treatment may remove residual transition metals from the substrate or chamber. While pre-treatment and / or post-treatment steps may 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 step. For example, in some embodiments, a plasma need not be generated while the halogen-containing precursor or precursors are being delivered into the processing chamber. Additionally, in some embodiments, the etch precursor may be hydrogen-free and the etching method may not include a hydrogen-containing precursor during etching, although a hydrogen-containing precursor may be used during one or both of the optional pre-treatment or post-treatment steps.

[0048] The precursors between each of the two steps can include a halogen-containing precursor, and in some embodiments, can include one or more of fluorine or chlorine. The specific precursor can be based on the precursor's bonding or stability. For example, in some embodiments, the first halogen-containing precursor can include a transition metal and / or be characterized by a specific gas density. The transition metal can include any transition metal capable of bonding with a halogen and dissociating under the operating conditions described below. Exemplary transition metals can include tungsten, niobium, or any other material, and can further include transition metal and halogen-containing precursors characterized by a gas density of about 3 g / L or greater, and can further be characterized by a gas density of about 4 g / L or greater, about 5 g / L or greater, about 6 g / L or greater, about 7 g / L or greater, about 8 g / L or greater, about 9 g / L or greater, about 10 g / L or greater, about 11 g / L or greater, about 12 g / L or greater, about 13 g / L or greater, or even greater.

[0049] These precursors may be characterized by relatively high thermal and chemical stability due to the nature of the bond between the heavy metal and the halogen. The precursors may also feature transition metals characterized by relatively low resistivity, which may further promote bond stability at lower temperatures and easy dissociation at higher temperatures. Correspondingly, the materials may be characterized by a resistivity of about 50 μΩ·cm or less, and may further be characterized by resistivities of about 40 μΩ·cm or less, about 30 μΩ·cm or less, about 20 μΩ·cm or less, about 15 μΩ·cm or less, about 10 μΩ·cm or less, about 5 μΩ or less, or even lower. The precursors may also include any number of carrier gases, which may include nitrogen, helium, argon, or other rare, inert, or useful precursors.

[0050] Some exemplary precursors that may have the above-described properties may include tungsten hexafluoride, tungsten pentachloride, niobium tetrachloride, or other transition metal halides, and other halides, including hydrogen fluoride, nitrogen trifluoride, or any organic fluoride. Precursors may also be co-flowed in various combinations. In some embodiments, nitrogen trifluoride or some other fluorine-containing precursor may be delivered to a remote plasma region where hydrogen and plasma are enhanced to produce a fluorinated aluminum surface in a first step. Etchant precursors according to some embodiments of the present technology may particularly include heavy metal halides that dissociate relatively easily at high temperatures, which may be characterized by stability at atmospheric conditions. For example, exemplary precursors may be characterized by relatively weak bonding at high temperatures, which may allow for controlled exposure of aluminum oxide to halogen etchants.

[0051] As a non-limiting example, tungsten hexafluoride can readily donate one or two fluorine atoms at high temperatures and accept an oxygen atom from, for example, aluminum oxide, and can be maintained in the gas phase. Correspondingly, tungsten oxide fluoride can be generated as a reaction by-product, which can be a gas molecule and can be vented or removed from the processing chamber. Because aluminum fluoride may not be volatile, a chlorine-, bromine-, or iodine-containing precursor (any of which may contain boron, titanium, tin, molybdenum, tungsten, or niobium) can be used to donate chlorine, bromine, or iodine and accept fluorine at the same temperature. While chlorine, bromine, or iodine cannot be readily donated to aluminum oxide, these materials can be donated to aluminum fluoride, while an etchant precursor can accept fluorine to produce two volatile components, including aluminum chloride, which can be vented from the processing chamber. Correspondingly, the process can remove aluminum oxide under processing conditions configured to exchange fluorine for chlorine after exchanging fluorine for oxygen between the etchant and the exposed surface, and further generate volatile aluminum by-products, while maintaining most of the etchant precursor and tungsten in vapor form. Correspondingly, tungsten and other heavy metals also encompassed by the present technology can have limited or essentially no interaction with the process during halogen delivery to the material to be etched. Due to the controlled delivery, tungsten oxide and other metal halides can easily remove aluminum oxide while being unable to etch or only slightly interacting with other exposed surfaces, which can result in improved selectivity over conventional techniques.

[0052] According to the present technology, process conditions can influence and accelerate etching. Because the etching reaction can proceed based on thermal dissociation of the halogen from the transition metal, the temperature can depend, at least in part, on the particular halogen and / or transition metal of the precursor to initiate dissociation. As shown, as the temperature increases above about 300°C, etching begins to occur or increase, which may indicate activation of precursor dissociation and / or reaction with aluminum oxide. As the temperature continues to increase, dissociation, as well as reaction with aluminum oxide, can be further accelerated.

[0053] Correspondingly, in some embodiments of the present technique, the etching method can be performed at substrate, pedestal, and / or chamber temperatures of about 300°C or greater, and can be performed at temperatures of about 350°C or greater, about 400°C or greater, about 450°C or greater, about 500°C or greater, or higher. The temperature can also be maintained at any temperature within these ranges, within narrower ranges included within these ranges, or between any of these ranges. In some embodiments, the method can be performed on a substrate that may have several created features, which can create a thermal budget. Correspondingly, in some embodiments, the method can be performed at temperatures of about 800°C or less, and can also be performed at temperatures of about 750°C or less, about 700°C or less, about 650°C or less, about 600°C or less, about 550°C or less, about 500°C or less, or lower.

[0054] The pressure within the chamber can also affect the process performed and at what temperature the halogen may dissociate from the transition metal. Correspondingly, in some embodiments, the pressure may be maintained at about 50 Torr or less, about 40 Torr or less, about 30 Torr or less, about 25 Torr or less, about 20 Torr or less, about 15 Torr or less, about 10 Torr or less, about 9 Torr or less, about 8 Torr or less, about 7 Torr or less, about 6 Torr or less, about 5 Torr or less, about 4 Torr or less, about 3 Torr or less, about 2 Torr or less, about 1 Torr or less, about 0.1 Torr or less, or less. The pressure may be maintained at any pressure within these ranges, within narrower ranges encompassed within these ranges, or between any of these ranges. In some embodiments, as the pressure increases above about 1 Torr, the amount of etching may be accelerated and may begin. Additionally, as the pressure continues to increase, etching may improve to a point before beginning to decrease and eventually stop as the pressure continues to increase.

[0055] 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 halogen atoms with heavy metal systems 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 aluminum oxide surface can be suppressed, or by-product aluminum fluoride 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 10 Torr.

[0056] The flow rate of the halogen-containing precursor can be adjusted (even in situ) to control the etching process. For example, the flow rate of the halogen-containing precursor can be reduced, maintained, or increased during the removal step. Increasing the flow rate of the halogen-containing precursor can increase the etch rate up to a saturation point. During any step of method 400, the flow rate of the fluorine-containing precursor can be between about 5 sccm and about 1000 sccm. Additionally, the flow rate of the halogen-containing precursor can be maintained at about 900 sccm or less, or about 800 sccm or less, or about 700 sccm or less, or about 600 sccm or less, or about 500 sccm or less, or about 400 sccm or less, or about 300 sccm or less, or about 200 sccm or less, or about 100 sccm or less, 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.

[0057] To provide additional control over the etching process, the halogen-containing precursor can be pulsed in some embodiments, and can be delivered continuously or in a series of pulses throughout the etching process, which can be constant or variable over time. Pulsed delivery can be characterized by a first period during which the halogen-containing precursor is flowed and a second period during which the halogen-containing precursor is paused or stopped. The durations of any pulse steps can be similar or different, with one period being longer than the other. In embodiments, the duration or continuous flow of precursor may be carried out for a period of about 1 second or greater, and may also be 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. In some embodiments, the etch rate may increase as the delivery of precursor is carried out for a longer period of time.

[0058] By performing processes according to embodiments of the present technology, aluminum oxide or other aluminum-containing materials can be selectively etched relative to other materials, including other oxides. For example, the present technology can selectively etch aluminum 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 aluminum oxide relative to either silicon oxide or other materials at a rate of at least about 20:1, and can also etch aluminum oxide relative to the listed silicon oxide or other materials at selectivities of about 25:1 or greater, about 30:1 or greater, about 50:1 or greater, about 100:1 or greater, about 150:1 or greater, about 200:1 or greater, about 250:1 or greater, about 300:1 or greater, about 350:1 or greater, about 400:1 or greater, about 450:1 or greater, about 500:1 or greater, or even higher. For example, etching performed in accordance with some embodiments of the present technology can etch aluminum oxide while substantially or essentially preserving silicon oxide or other materials, such as nitrides of silicon, titanium, tantalum, or other materials.

[0059] Selectivity may be based in part on the precursor used and its ability to dissociate over a more controlled temperature range. For example, conventional precursors containing nitrogen trifluoride may not dissociate easily at temperatures below about 500°C at operating pressures and may also be characterized by a slower reaction rate with the material to be removed, which may extend the exposure time of other materials on the substrate and further increase the removal of those materials. Correspondingly, conventional dry etchants may not be able to produce the etching selectivity of embodiments of the present technology. Similarly, because wet etchants easily remove silicon oxide, wet etchants may also not be able to selectively etch at a rate comparable to embodiments of the present technology.

[0060] The above-described method can enable the removal of aluminum-containing materials relative to some other exposed material. Utilizing transition metals as described above can provide improved etching of aluminum oxide, which can increase selectivity over conventional techniques and improve etch access in small pitch features.

[0061] In the foregoing description, for purposes of explanation, numerous details are 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 particular embodiments may be practiced without some of these details or with additional details.

[0062] Although several embodiments have been disclosed, those skilled in the art will recognize that various modifications, alternative structures, and equivalents may be used without departing from the spirit of the above-described embodiments. Additionally, some well-known processes and elements have not been described to avoid unnecessarily obscuring the present technology. Correspondingly, the foregoing description should not be construed as limiting the scope of the present technology. Additionally, 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.

[0063] 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.

[0064] 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 layer" includes a reference to one or more components and equivalents known to those skilled in the art, and so forth.

[0065] Additionally, the words "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, operations, or groups.

Claims

1. 1. An etching method comprising: flowing a halogen-containing precursor into a substrate processing region of a semiconductor processing chamber, the halogen-containing precursor characterized by a gas density of 5 g / L or greater; contacting the halogen-containing precursor with a substrate contained within the plasma-free substrate processing region, the substrate having an aluminum-containing material thereon with an exposed region, the contacting producing an aluminum halide material; flowing an etchant precursor into the substrate processing region; contacting the aluminum halide material with the etchant precursor in the plasma-free substrate processing region; removing the aluminum halide material to expose a layer of semiconductor material underneath the aluminum-containing material; Including, the halogen-containing precursor comprises a plasma effluent of a fluorine-containing precursor, and the etchant precursor comprises boron trichloride; Etching method.

2. The etching method of claim 1 , wherein the aluminum-containing material comprises aluminum oxide.

3. contacting the substrate with the halogen-containing precursor produces a non-volatile aluminum halide material and a volatile metal oxide; contacting the aluminum halide material with the etchant precursor to produce a volatile aluminum halide material; The etching method according to claim 1 .

4. The etching method of claim 1 , wherein the etching method is carried out at a temperature of 300° C. or greater.

5. 10. The etching method of claim 1, wherein the etching method is carried out at a pressure of 0.1 Torr or greater.

6. 6. The etching method of claim 5, wherein the etching method is carried out at a pressure of 50 Torr or less.

7. 10. The etching method of claim 1, further comprising a pretreatment occurring before flowing the halogen-containing precursor, the pretreatment comprising contacting the substrate with a plasma comprising one or more of oxygen, hydrogen, or nitrogen.

8. 2. The etching method of claim 1, further comprising a post-treatment performed after the etching method, the post-treatment comprising contacting the substrate with a plasma comprising one or more of oxygen, hydrogen, or nitrogen.

9. 1. An etching 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 substrate processing region of a semiconductor processing chamber; contacting the treatment plasma effluents with a substrate contained within the substrate processing region, the substrate having an aluminum-containing material thereon with an exposed region, the treatment plasma effluents configured to remove residue from a surface of the aluminum-containing material; flowing a first halogen-containing material into the plasma-free substrate processing region of the semiconductor processing chamber; contacting the substrate with the first halogen-containing material; flowing a second halogen-containing precursor into the substrate processing region of the semiconductor processing chamber; removing the aluminum-containing material to expose a layer of semiconductor material underneath the aluminum-containing material; Including, 1. A method of etching wherein the first halogen-containing material comprises a plasma effluent of a fluorine-containing precursor and the second halogen-containing precursor comprises boron trichloride.

10. 10. The etching method of claim 9, further comprising: ceasing formation of the plasma before flowing the first halogen-containing material.

11. The etching method of claim 9, wherein the etching method is carried out at a temperature of 300° C. or greater.

12. 10. The etching method of claim 9, wherein the etching method is carried out at a pressure of 0.1 Torr or greater.

13. 10. The etching method of claim 9, further comprising a post-treatment performed after the etching method, the post-treatment comprising contacting the substrate with a plasma comprising one or more of oxygen, hydrogen, or nitrogen.

14. 1. An etching method comprising: flowing a fluorine-containing precursor into a substrate processing region of a semiconductor processing chamber, the fluorine-containing precursor characterized by a gas density of 5 g / L or greater; contacting the fluorine-containing precursor with a substrate contained within the plasma-free substrate processing region, the substrate having an aluminum-containing material thereon with an exposed region; flowing a chlorine-containing precursor into the substrate processing region of the semiconductor processing chamber; contacting the substrate with the chlorine-containing precursor in the plasma-free substrate processing region; removing the aluminum-containing material to expose a layer of semiconductor material underneath the aluminum-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 plasma effluents; Including, the fluorine-containing precursor comprises a plasma effluent of a fluorine-containing precursor, and the chlorine-containing precursor comprises boron trichloride; Etching method.

15. 15. The etching method of claim 14, wherein the treatment plasma effluents are configured to remove residual tungsten or niobium from one or more of the substrate or the semiconductor processing chamber.

16. 15. The etching method of claim 14, wherein the etching method is carried out at a temperature of 300° C. or greater and a pressure of 0.1 Torr or greater.

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