System and method for removing aluminum-containing film

Abstract

To provide a method for etching which flows a halogen-containing precursor into a substrate processing region of a semiconductor processing chamber.SOLUTION: The method includes bringing a substrate stored in a substrate processing region and a halogen-containing precursor having a gas density of approximately at least 5 g / L into contact with each other. The substrate defines the exposure region of the aluminum-containing material. The method also includes: generating an aluminum halide by the contact; flowing an etchant precursor into the substrate processing region; bringing the aluminum halide material and the etchant precursor into contact with each other; and removing the aluminium halide material.SELECTED DRAWING: Figure 4

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. patent application Ser. No. 17 / 018,229, entitled “SYSTEMS AND METHODS FOR ALUMINUM-CONTAINING FILM REMOVAL,” filed Sep. 11, 2020, which is incorporated by reference in its entirety. [Technical field]

[0002] The present 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 produce 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 pattern of photoresist 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 variety of materials, circuits, and processes, etching processes have been developed that are selective to a variety of materials.

[0004] Etching processes may 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 may have difficulty penetrating some constrained trenches and may sometimes deform the remaining materials. Dry etching, which is performed in a localized plasma formed within the substrate processing region, can penetrate more constrained trenches and may cause less deformation of the delicate remaining structures. However, the localized plasma may damage the substrate due to electrical arcs that occur when the localized plasma discharges.

[0005] Thus, there is a need for improved systems and methods that can be used to fabricate high quality devices and structures. The present technique 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 an exposed region 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 may include a transition metal and the etchant precursor may be or include a chlorine-containing precursor. The halogen-containing precursor may include tungsten or niobium. The aluminum-containing material may be or include aluminum oxide. The etching method may be a plasma-free etching process. 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 etching method may be performed at a pressure of about 50 Torr or less. The method may include a pretreatment performed before flowing the halogen-containing precursor. The pretreatment may include contacting the substrate with a plasma including one or more of oxygen, hydrogen, or nitrogen. The method may include a post-treatment performed after the etching method. The post-treatment may 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 processing precursor comprising one or more of oxygen, hydrogen, or nitrogen to generate processing plasma effluents. The method may include flowing the processing plasma effluents into a substrate processing region of a semiconductor processing chamber. The method may include contacting the processing plasma effluents with a substrate contained in the substrate processing region. The substrate may define an exposed region of aluminum-containing material. The processing plasma effluents may be configured to remove residues from a surface of the aluminum-containing material. The method may include flowing a first halogen-containing precursor into a substrate processing region of a 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 a semiconductor processing chamber. The method may include removing the aluminum-containing material.

[0009] In some embodiments, the first halogen-containing material may include a plasma effluent of a tungsten or niobium or fluorine-containing precursor. The second halogen-containing precursor may be or include boron trichloride. The method may include ceasing 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 including 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 a substrate processing region of a 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 a processing plasma effluent. The method may include contacting the substrate with the processing plasma effluent.

[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 carried out at a temperature of about 300° C. or greater and a pressure of about 0.1 Torr or greater.

[0012] Such techniques may provide numerous advantages over conventional systems and techniques. For example, the process may allow for dry etching that may preserve substrate features. In addition, 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 description of the drawings]

[0014] [Figure 1] FIG. 1 shows a top view of an 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 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. [Diagram 3] FIG. 1 illustrates a bottom view of an exemplary showerhead in accordance with some embodiments of the present technique. [Figure 4] 5 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 in accordance with an embodiment of the present technique; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 to scale. Furthermore, as schematic diagrams, the figures are provided to aid in understanding and may not include all aspects or information as 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 numbers. Furthermore, various components of the same type may be distinguished by a letter following the reference number that distinguishes between the similar components. If only a first reference number is used in this specification, the description may apply to any similar component having the same first reference number, whatever its letter.

[0017] In many different semiconductor processes, diluted acids may be used to clean and remove materials from substrates. 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 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 may be used that utilize precursors that are delivered to the substrate. For example, plasma-enhanced processes may also perform dry etching by selectively etching materials by enhancing precursors through the plasma.

[0018] Wet etchants using aqueous solutions or water-based processes may work effectively for certain substrate structures, but water may pose challenges in various conditions. For example, utilizing water during an etching process may cause problems when placed on a substrate that includes 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 been formed on the substrate. If water is used in any way during etching, an electrolyte may be created. When the electrolyte comes into contact with the metallic material, galvanic corrosion may occur between dissimilar metals, and furthermore, the metal may be corroded or displaced in various processes. In addition, pattern deformation and collapse may occur in microstructures due to the surface tension of the water diluent. 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 problems 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 easily 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 to be etched, and in some embodiments, the process can be plasma-free during etching. By utilizing certain 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 allow for improved etching over conventional techniques.

[0021] While the remainder of the disclosure will routinely identify specific etch processes utilizing the disclosed technology, it will be readily appreciated 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 etch techniques, including intermediate and back-end-of-line processes, and other etch techniques 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 etch processes or etch 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 an 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 provide substrates of various sizes that are received by a robot arm 104 and placed in a low pressure holding area 106 and then placed in 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 etch 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 a chamber separate from the fabrication system shown in various embodiments. Of course, additional configurations of dielectric film deposition, etching, annealing, and curing chambers are contemplated in the system 100.

[0024] 2A shows a cross-sectional view of an exemplary processing chamber system 200 having a plasma generation region separated inside 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 through a gas injection assembly 205 into a first plasma region 215. A remote plasma system (RPS) 201 can be optionally included in the system and can process a first gas. The first gas then travels through the gas injection assembly 205. The gas injection 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 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 be operable 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 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 that is narrow at the top and widens toward the bottom. The face plate 217 may additionally be flat as shown and may include a number of through channels used to distribute process gases. Plasma generating gases and / or plasma excited species may pass through a number of holes, shown in FIG. 2B, in the face plate 217 in accordance with use of the RPS 201 and may be more uniformly delivered into the first plasma region 215.

[0027] An exemplary configuration can include gas injector assembly 205 communicating with gas feed region 258 separated from first plasma region 215 by faceplate 217 such that the 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 to feed region 258, gas injector 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, allowing 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, allowing a capacitively coupled plasma (CCP) to form in the first plasma region. A baffle (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 number of apertures throughout its structure, configured to suppress the migration of ionically charged species leaving 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 discussed above, migration of ionic species through the apertures may be reduced, and in some cases may be completely prevented. Controlling the amount of ionic species passing through the ion suppressor 223 may advantageously provide improved control over the gas mixture that is brought into contact 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, by adjusting the ion concentration of the gas mixture, the etch selectivity of the gas mixture can be significantly changed, e.g., the etch ratio of SiNx:SiOx, the etch ratio of Si:SiOx, etc. In alternative embodiments where deposition is performed, it is also possible to change the balance between conformal and flowable style deposition of the dielectric material.

[0029] The apertures of the ion suppressor 223 may be configured to control the passage of active gas (i.e., ionic, radical, and / or neutral species) through the ion suppressor 223. For example, the aspect ratio of the apertures (i.e., diameter relative 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 of 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. An adjustable electrical bias may be applied to the ion suppressor 223 as an additional means of controlling the flow rate of ionic species through 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 of the ion suppressor and react with the substrate. It should be noted that complete removal of ionically charged species in the reaction region around the substrate may not be performed 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 that aids in the process at a certain 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 way, 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 that may be damaged, displaced, or otherwise distorted if the generated plasma were to directly contact them. Furthermore, allowing the plasma to contact the substrate or approach the substrate level can increase the rate of etching performed by oxide species. Correspondingly, if the exposed region of material is an oxide, the material can be further protected by keeping the plasma away from the substrate.

[0032] The processing system may further include a power supply 240 electrically connected to the processing chamber. The power supply 240 provides power to the face plate 217, the ion suppressor 223, the showerhead 225, and / or the pedestal 265 to generate a plasma in the first plasma region 215 or the processing region 233. The power supply may be configured to deliver an adjustable amount of power to the chamber according to the process being performed. Such a configuration may allow for the use of an adjustable plasma in the process being performed. Unlike remote plasma units, which are often provided with 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 allow for the etching profile formed by the precursors to be enhanced by developing specific plasma characteristics such that the precursors may separate in a specific manner.

[0033] A plasma may be ignited in either 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 ignite 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.

[0034] 2B is a detailed view 253 of features that affect the distribution of process gas through faceplate 217. As shown in FIGS. 2A and 2B, the intersection of faceplate 217, cooling plate 203, and gas injector assembly 205 defines a gas delivery region 258. Process gas may be supplied to gas delivery region 258 from gas injector assembly 205. Gas may fill gas delivery region 258 and flow through apertures 259 in faceplate 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 be partially or completely prevented from flowing back into gas delivery region 258 after traversing faceplate 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 can include an upper plate 214 and a lower plate 216. The plates can be coupled together to define a space 218 between the plates. The plates can 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 channels formed can be configured to provide fluidic access through the lower plate 216 from the space 218 only via the second fluid channel 221, and the first fluid channel 219 can be fluidically isolated from the space 218 between the plates and the second fluid channel 221. The space 218 can be fluidically 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 a number of 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 over 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 above-mentioned chambers may be used in carrying out 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 may 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 prior to the steps described. The method may include several optional steps, which may or may not be specifically associated with some embodiments of the method according to the present technology. For example, many of the steps are described to provide a broader scope of the processes performed, but are not critical to the present technology or may be performed by alternative methods as described further below. The method 400 may 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 any number of additional materials and features having various properties and aspects as shown in the figures.

[0039] The method 400 may or may not include optional steps to develop the semiconductor structure to a particular fabrication step. It should be understood that the method 400 may be performed on any number of semiconductor structures, including the exemplary structure that may perform an oxide removal step, or on the substrate 505 shown in FIG. 5A. The exemplary semiconductor structure may include a trench, via, or other recessed feature 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 a recess, trench, via, or insulating structure. The exposed material at any time during the etching process may be or include a metal material, a dielectric material, a contact material, a transistor material, or any other material that may be used in a semiconductor process, such as for a gate. 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 nitrides of titanium, tantalum, or other materials.

[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 that contain aluminum-containing materials are encompassed as well. Other exemplary structures can include two-dimensional and three-dimensional structures common in semiconductor manufacturing, where aluminum-containing materials, such as aluminum oxide, are removed relative to one or more other materials, since the present technology can selectively remove aluminum-containing materials relative to other exposed materials, such as silicon-containing materials, and any of the other materials described elsewhere. In addition, while high aspect ratio structures can benefit from the present technology, the technology can be applicable to lower aspect ratios and any other structures as well.

[0041] For example, a layer of material according to the present technology may be characterized by any aspect ratio or height to width ratio of the structure, but in some embodiments, the material may 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 the exemplary structure may be about 10:1 or more, about 20:1 or more, about 30:1 or more, about 40:1 or more, about 50:1 or more, or more. Additionally, each layer may 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 above numerical values, such as 20.5 nm, 1.5 nm, etc. This combination of high aspect ratio and minimal thickness may prevent many conventional etching processes or may 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 may occur with conventional techniques.

[0042] Although the method 400 may be performed in embodiments to remove exposed aluminum-containing material, any number of oxides or aluminum-containing materials may be removed in any number of structures in embodiments of the present technology. The method may include specific steps for removing aluminum-containing materials and may include one or more optional steps for preparing or treating the aluminum-containing material. For example, in the exemplary substrate structure, residues of previous processing may be present on the film to be removed, such as aluminum oxide. For example, residual photoresist or by-products from previous processing may be present on the aluminum oxide layer. These materials may block access to the aluminum oxide or may interact with etchants differently than a clean aluminum oxide surface, which may impede one or more aspects of the etch. Correspondingly, in some embodiments, optional pre-treatment of the aluminum-containing film or aluminum-containing material may be performed in optional step 405. Exemplary pre-treatment steps may include, for example, thermal treatment, wet treatment, or plasma treatment, which may be performed in chamber 200 and in any number of chambers that may 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 the above-mentioned chamber 200 can be utilized 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 be struck. The plasma effluent can be flowed to the substrate and can 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 to produce 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 flowing halogen-containing precursors, including a first halogen-containing precursor, into a substrate processing region of a semiconductor processing chamber housing the substrate described or any other substrate at step 410. The halogen-containing precursor may be flowed through a remote plasma region of the processing chamber, such as region 215 described above, but in some embodiments, method 400 may not utilize plasma effluents during the etching step. For example, method 400 may flow a fluorine-containing or other halogen-containing precursor into a substrate without exposing the precursor to a plasma and may remove aluminum-containing materials without generating plasma effluents. In some embodiments, the halogen-containing precursor may be plasma enhanced and may be performed in a remote plasma region to prevent materials on the substrate from contacting plasma effluents. The halogen-containing precursor may contact a semiconductor substrate containing exposed aluminum-containing materials and may generate fluorinated materials, such as aluminum fluoride or aluminum halide materials, that may remain on the semiconductor substrate. The halogen-containing precursor may donate one or more fluorine atoms while accepting one or more oxygen atoms in some embodiments. Some halogen-containing precursors, such as plasma-enhanced precursors, may provide fluorine radicals, while other plasma radicals may accept oxygen from the film.

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

[0047] As mentioned 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 performed, which can also be a dry etch. Correspondingly, 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 can be performed to remove residues from the substrate or chamber, including post-treatment at optional step 425. Post-treatment can include steps similar to pre-treatment and can include any of the precursors or steps described above for pre-treatment. Post-treatment can, in some embodiments, remove residual transition metals from the substrate or chamber. Pre-treatment and / or post-treatment steps can include plasma generation and delivery of plasma effluents to the substrate, although it should be understood that a plasma may not be formed during the etching steps. For example, in some embodiments, a plasma may not be generated while the halogen-containing precursor or precursors are delivered into the process chamber. Additionally, in some embodiments, the etch precursor may be hydrogen-free and the etching method may not include a hydrogen-containing precursor during the etch, 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 may include halogen-containing precursors, and in some embodiments may include one or more of fluorine or chlorine. The particular precursor may be based on the binding or stability of the precursor. For example, in some embodiments, the first halogen-containing precursor may include a transition metal and / or may be characterized by a particular gas density. The transition metal may include any transition metal that can bind with a halogen and dissociate under the operating conditions described below. Exemplary transition metals may include tungsten, niobium, or any other material, and may further include transition metal and halogen-containing precursors characterized by a gas density of about 3 g / L or more, and may further be characterized by a gas density of about 4 g / L or more, about 5 g / L or more, about 6 g / L or more, about 7 g / L or more, about 8 g / L or more, about 9 g / L or more, about 10 g / L or more, about 11 g / L or more, about 12 g / L or more, about 13 g / L or more, or more.

[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 be characterized by transition metals that are 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 a resistivity 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 less. 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 include the above-mentioned characteristics may include tungsten hexafluoride, tungsten pentachloride, niobium tetrachloride, or other transition metal halides, and hydrogen fluoride, nitrogen trifluoride, or other halides including any organic fluoride. The precursors may also be flowed together 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 surface of aluminum in a first step. The etchant precursors according to some embodiments of the present technology may include heavy metal halides that dissociate relatively easily at high temperatures, and the heavy metal halides may be characterized by stability at atmospheric conditions. For example, exemplary precursors may be characterized by relatively weak binding at high temperatures, which may allow controlled exposure of aluminum oxide to halogen etchants.

[0051] As a non-limiting example, tungsten hexafluoride can easily donate one or two fluorine atoms at high temperatures and can accept oxygen atoms from aluminum oxide, etc., 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 exhausted or removed from the processing chamber. Since aluminum fluoride may not be volatile, a chlorine-containing precursor, a bromine-containing precursor, or an 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. Although chlorine, bromine, or iodine cannot be easily donated to aluminum oxide, the materials can be donated to aluminum fluoride, while the etchant precursor can accept fluorine to generate two volatile components, including aluminum chloride, which can be exhausted 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 can also generate volatile aluminum by-products and maintain 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 transfer to the material to be etched. Due to the controlled transfer, tungsten oxide and other metal halides can easily remove aluminum oxide while not being able to etch or only slightly interact with other exposed surfaces, which can result in improved selectivity over conventional techniques.

[0052] According to the present technology, the process conditions can affect and accelerate the etching. The etching reaction can proceed based on thermal dissociation of the halogen from the transition metal, so 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 the dissociation of the precursor and / or reaction with aluminum oxide. As the temperature continues to increase, dissociation can be further promoted, as can reaction with aluminum oxide.

[0053] Correspondingly, in some embodiments of the present technology, the etching method can be performed at a substrate temperature, pedestal temperature, and / or chamber temperature of about 300° C. or more, and can be performed at temperatures of about 350° C. or more, about 400° C. or more, about 450° C. or more, about 500° C. or more, or higher. The temperature can be maintained at any temperature within these ranges, narrower ranges included in 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 may result in a thermal budget. Correspondingly, in some embodiments, the method can be performed at a temperature of about 800° C. or less, and can 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 in the chamber can also affect the process performed and at what temperature the halogen can dissociate from the transition metal. Correspondingly, in some embodiments, the pressure can 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 can be maintained at any pressure within these ranges, within narrower ranges contained within these ranges, or between any of these ranges. In some embodiments, as the pressure increases beyond about 1 Torr, the amount of etching can be accelerated and initiated. Additionally, as the pressure continues to increase, the etching can improve to a point before it begins to decrease, and may eventually stop as the pressure continues to increase.

[0055] Without being bound to any particular theory, the pressure in the chamber can affect the process with the precursors mentioned above. At low pressure, the flow across the substrate can be reduced, which can likewise reduce dissociation. As the pressure increases, the interaction between the etchant precursor and the substrate can be increased, which can increase the reaction and etching rate. However, as the pressure continues to increase, the 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, and in addition, as the pressure continues to increase, the interaction with the aluminum oxide surface can be suppressed, or the by-product aluminum fluoride can be reintroduced into the film being etched, further limiting removal. Correspondingly, in some embodiments, the pressure in the process chamber can be maintained at about 10 Torr or less in some embodiments.

[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. By increasing the flow rate of the halogen-containing precursor, the etch rate can be increased to a saturation point. During any step of the method 400, the flow rate of the fluorine-containing precursor can be between about 5 sccm and about 1000 sccm. In addition, 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 add more control to the etching process, the halogen-containing 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 change over time.Pulsed delivery can be characterized by a first period during which the halogen-containing precursor flows, and a second period during which the halogen-containing precursor is paused or stopped.The periods of any pulse steps can be similar or different from each other, where one period is 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 more, and may be about 2 seconds or more, about 3 seconds or more, about 4 seconds or more, about 5 seconds or more, about 6 seconds or more, about 7 seconds or more, about 8 seconds or more, about 9 seconds or more, about 10 seconds or more, about 11 seconds or more, about 12 seconds or more, about 13 seconds or more, about 14 seconds or more, about 15 seconds or more, about 20 seconds or more, about 30 seconds or more, about 45 seconds or more, about 60 seconds or more, or more. The time may 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 carrying out the process according to the embodiment of the present technology, aluminum oxide or other aluminum-containing materials can be selectively etched with respect to other materials, including other oxides. For example, the present technology can selectively etch aluminum oxide with respect to exposed areas of metal, dielectrics, including silicon-containing materials, including silicon oxide, or other materials. The embodiment of the present technology can etch aluminum oxide with respect to either silicon oxide or other materials at a rate of at least about 20:1, and can further etch aluminum oxide with respect to the silicon oxide or other materials described with a selectivity of about 25:1 or more, about 30:1 or more, about 50:1 or more, about 100:1 or more, about 150:1 or more, about 200:1 or more, about 250:1 or more, about 300:1 or more, about 350:1 or more, about 400:1 or more, about 450:1 or more, about 500:1 or more, or more. For example, etches performed according to some embodiments of the present technique 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 in a more controlled temperature range. For example, conventional precursors including 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, further increasing the removal of the material. Correspondingly, conventional dry etchants may not be able to produce the etch selectivity of the embodiments of the present technology. Similarly, wet etchants may also not be able to selectively etch at a rate comparable to the embodiments of the present technology, since wet etchants easily remove silicon oxide.

[0060] The above 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 preceding description, 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.

[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. In addition, some well-known processes and elements have not been described in order to avoid unnecessarily obscuring the present technology. Correspondingly, the above description should not be interpreted as limiting the scope of the present technology. In addition, although 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 limits 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 in that stated range is included. The upper and lower limits of these narrower ranges may be individually included or excluded in the range, and each range where one or both limits are included or neither are included in the narrower range is also included within the scope of the technology, subject to any specifically excluded limit in the stated range. When a stated range includes one or both limits, ranges excluding one or both of the 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 the steps of: flowing a halogen-containing precursor into a substrate processing region of a semiconductor processing chamber, the halogen-containing precursor being characterized by a gas density of about 5 g / L or greater; contacting a substrate contained within the substrate processing region with the halogen-containing precursor, the substrate defining an exposed region of an aluminum-containing material, 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; removing said aluminum halide material; An etching method comprising:

2. 2. The etching method of claim 1, wherein the halogen-containing precursor comprises a transition metal and the etchant precursor comprises a chlorine-containing precursor.

3. The etching method of claim 2 , wherein the halogen-containing precursor comprises tungsten or niobium.

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

5. The etching method of claim 1 , wherein the etching method comprises a plasma-free etching process.

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

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

8. 8. The etching method of claim 7, wherein the etching method is carried out at a pressure of about 50 Torr or less.

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

10. 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.

11. 1. An etching method comprising the steps of: forming a plasma of a process precursor comprising one or more of oxygen, hydrogen, or nitrogen to generate a process plasma effluent; flowing the processing plasma effluent into a substrate processing region of a semiconductor processing chamber; contacting a substrate contained within the substrate processing region with the treatment plasma effluents, the substrate defining an exposed region of aluminum-containing material, the treatment plasma effluents configured to remove residues from a surface of the aluminum-containing material; flowing a first halogen-containing material into the 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 said aluminum-containing material; An etching method comprising:

12. 12. The etching method of claim 11, wherein the first halogen-containing material comprises a plasma effluent of a tungsten or niobium or fluorine-containing precursor and the second halogen-containing precursor comprises boron trichloride.

13. 12. The etching method of claim 11, further comprising ceasing formation of the plasma prior to flowing the first halogen-containing material.

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

15. 12. The etching method of claim 11, wherein the etching method is carried out at a pressure of about 0.1 Torr or greater.

16. 12. The etching method of claim 11, 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.

17. 1. An etching method comprising the steps of: flowing a fluorine-containing precursor into a substrate processing region of a semiconductor processing chamber, the fluorine-containing precursor being characterized by a gas density of about 5 g / L or greater; contacting a substrate contained within the substrate processing region with the fluorine-containing precursor, the substrate defining an exposed region of an aluminum-containing material; flowing a chlorine-containing precursor into the substrate processing region of the semiconductor processing chamber; contacting the substrate with the chlorine-containing precursor; removing said aluminum-containing material; forming a plasma of a process precursor comprising one or more of oxygen, hydrogen, or nitrogen to generate a process plasma effluent; contacting the substrate with the plasma effluent; An etching method comprising:

18. 20. The etching method of claim 17, wherein the fluorine-containing precursor comprises tungsten or niobium and the chlorine-containing precursor comprises boron.

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

20. 20. The etching method of claim 17, wherein the etching method is carried out at a temperature of about 300° C. or greater and at a pressure of about 0.1 Torr or greater.

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