Targeted removal of metal oxides

Abstract

An exemplary etching method may include modifying an exposed surface of a metal oxide layer on a substrate housed in a processing region of a semiconductor processing chamber to create modified portions of the metal oxide. The method may include contacting the modified portions of the metal oxide with a fluorine-containing precursor. The contacting may create a metal oxyfluoride material. The method may include flowing an etchant precursor into the processing region. The method may include contacting the metal oxyfluoride material with the etchant precursor. The method may include removing the metal oxyfluoride material.

Description

[Technical Field]

[0001] cross reference This application claims priority to U.S. Application No. 17 / 376,337, filed July 15, 2021, the disclosure of which is incorporated herein by reference in its entirety for all purposes.

[0002] The present technology relates to semiconductor processes and devices, and more particularly to directional etching of metal-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 patterns in photoresist into underlying layers, thinning layers, or thinning the lateral dimensions of features already present on a surface. It is often desirable to have an etching process that etches one material more quickly than another, for example, to facilitate the pattern transfer process. Such an etching process is said to be selective to the first material. As a result of the diversity of materials, circuits, and processes, etching processes 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 can preferentially remove some oxide dielectrics over other dielectrics and materials. However, wet processes can have difficulty penetrating some constrained trenches and sometimes deform the remaining material. Dry etching, performed in a localized plasma formed within the substrate processing region, can penetrate more constrained trenches and results in less deformation of the fragile remaining structures. However, localized plasma can damage the substrate due to the generation of electric arcs when the localized plasma discharges.

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

[0006] An exemplary etching method may include modifying an exposed surface of a metal oxide layer on a substrate housed in a processing region of a semiconductor processing chamber to create a modified portion of the metal oxide. The method may include contacting the modified portion of the metal oxide with a fluorine-containing precursor. The contacting may create a metal oxyfluoride material. The method may include flowing an etchant precursor into the processing region. The method may include contacting the metal oxyfluoride material with the etchant precursor. The method may include removing the metal oxyfluoride material.

[0007] In some embodiments, the etchant precursor may be or include a chlorine-containing precursor. The metal oxide may be or include hafnium oxide. The fluorine-containing precursor may be or include hydrogen fluoride or a plasma-enhanced fluorine-containing precursor. The plasma-enhanced fluorine-containing precursor may be formed in a remote plasma region of the semiconductor processing chamber. Modifying the exposed surface of the metal oxide layer may include forming a plasma of the oxygen-containing precursor to create oxygen-containing plasma effluents. Modifying the exposed surface of the metal oxide layer may include directing the oxygen-containing plasma effluents toward the exposed surface of the metal oxide layer. The plasma effluents may cause a portion of the metal oxide to become amorphous metal oxide. The plasma of the oxygen-containing precursor may be formed in the processing region at a plasma power greater than or about 100 W. The semiconductor processing chamber may be maintained plasma-free while flowing the etchant precursor into the processing region. The temperature in the semiconductor processing chamber may be increased prior to contacting the metal oxyfluoride material with the etchant precursor. The pressure in the semiconductor processing chamber can be maintained at less than or about 5 Torr during flow of the fluorine-containing precursor. The pressure in the semiconductor processing chamber can be maintained at more than or about 15 Torr during flow of the etchant precursor into the processing region.

[0008] Some embodiments of the present technology may include an etching method. The method may include modifying an exposed surface of a layer of metal-containing material on a substrate housed in a processing region of a semiconductor processing chamber to create a modified portion of the metal-containing material. The method may include flowing a first halogen-containing precursor into a remote plasma region of the semiconductor processing chamber while striking a plasma to create plasma effluents. The method may include contacting the modified portion of the metal-containing material with the plasma effluents. The contacting may create a metal fluoride material. The method may include flowing a second halogen-containing precursor into the processing region. The method may include contacting the metal fluoride material with the second halogen-containing precursor. The method may include removing the metal fluoride material.

[0009] In some embodiments, the first halogen-containing precursor may be or include fluorine. The second halogen-containing precursor may be or include boron trichloride, and the metal-containing material may be or include an oxide or nitride containing aluminum, hafnium, zirconium, or titanium. The method may include terminating plasma formation prior to flowing the second halogen-containing precursor. Contacting the transformed portion of the metal-containing material with plasma effluents may be carried out at a first temperature. Contacting the metal fluoride material with the second halogen-containing precursor may be carried out at a second temperature higher than the first temperature. The first halogen-containing precursor may be or include nitrogen trifluoride. The method may include flowing hydrogen with the first halogen-containing precursor. The flow rate of the hydrogen may be at least twice the flow rate of the first halogen-containing precursor. Transforming the exposed surface of the layer of metal-containing material may include forming a plasma of the oxygen-containing precursor to create oxygen-containing plasma effluents. Modifying the exposed surface of the layer of metal-containing material may include directing plasma effluents at the exposed surface of the layer of metal-containing material.

[0010] Some embodiments of the present technology may include an etching method. The method may include forming a plasma of an oxygen-containing precursor to create oxygen-containing plasma effluents. The method may include directing the oxygen-containing plasma effluents toward a metal oxide layer on a substrate housed in a processing region of a semiconductor processing chamber to create a transformed portion of the metal oxide. The method may include flowing a fluorine-containing precursor into a remote plasma region of the semiconductor processing chamber while striking a plasma in the remote plasma region to create the plasma effluents. The method may include contacting the transformed portion of the metal oxide with the plasma effluents. The contacting may create a metal oxyfluoride material. The method may include flowing a chlorine-containing precursor into the processing region. The method may include contacting the metal oxyfluoride material with the chlorine-containing precursor. The method may include removing the metal oxyfluoride material.

[0011] Such techniques may offer numerous benefits over conventional systems and techniques. For example, the process may allow directional dry etching to be performed, which may preserve substrate features. Additionally, the process may increase the etch rate of metal-containing films relative to other exposed materials on the substrate. These and other embodiments, along with many of their advantages and features, are described in more detail in conjunction with the following description and accompanying figures.

[0012] 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]

[0013] [Figure 1] FIG. 1 illustrates a top view of an embodiment of an exemplary processing system in accordance with some embodiments of the present technique. [Figure 2A] 1 is a schematic cross-sectional view of an exemplary processing chamber in accordance with some embodiments of the present technique; [Figure 2B]2B is 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 illustrates a bottom view of an exemplary showerhead in accordance with some embodiments of the present technique. [Figure 4] 1A-1C illustrate exemplary operations in a method according to some embodiments of the present technology. [Figure 5A] 1A-1C are schematic cross-sectional views of etched material in accordance with some embodiments of the present technique; [Figure 5B] 1A-1C are schematic cross-sectional views of etched material in accordance with some embodiments of the present technique; [Figure 5C] 1A-1C are schematic cross-sectional views of etched material in accordance with some embodiments of the present technique; [Figure 5D] 1A-1C are schematic cross-sectional views of etched material in accordance with some embodiments of the present technique; DETAILED DESCRIPTION OF THE INVENTION

[0014] Some of the figures are included as schematic diagrams. It should be understood that the figures are for illustrative purposes and should not be considered to scale unless expressly stated to be to scale. Furthermore, as schematic diagrams, the figures are provided to aid in understanding and may not include all aspects or information compared to realistic representations and may include additional or exaggerated material for illustrative purposes.

[0015] In the accompanying figures, similar components and / or features may have the same reference label. Furthermore, various components of the same type may be distinguished by following the reference label with a letter that distinguishes between the similar components. If only a first reference label is used herein, the description is applicable to any of the similar components having the same first reference label, regardless of its letter.

[0016] As scaling of complementary metal oxide semiconductor materials becomes more difficult, silicon dioxide is often replaced with high-k dielectric materials. However, many high-k dielectric materials, such as transition metal oxides or nitrides or other metal oxides or nitrides, can pose implementation challenges. For example, deposition may be followed by one or more removal operations. Many transition metal materials are characterized by more metal-like properties compared to other dielectrics, which can cause removal and etch-back operations to be less selective. Furthermore, as device structures become increasingly complex, the material to be removed may be exposed along with many additional materials that must be maintained during subsequent processing.

[0017] Metal oxides are becoming increasingly popular high-k dielectric materials that can provide improved transistor performance while maintaining layer thickness. More generally, when metal oxides are incorporated, processing of metal oxide films is beginning to create layers of material characterized by increased density, which can pose integration challenges. For example, during etch-back or removal operations, denser metal oxide layers, such as layers pre-annealed during processing or after deposition, can reduce etch selectivity, which can increase damage to surrounding materials on the substrate. Traditional processing of metal oxides may utilize isotropic etching processes, which can cause increased exposure to surrounding materials and reduce selectivity by causing further etching of other materials. The present technology can increase the ability to incorporate dense metal oxide materials by providing a directional removal process that can enable controlled removal of metal oxides from various structures, and the directional removal process can be selective to some materials that can be masked and / or maintained exposed during removal.

[0018] While the remaining disclosure routinely identifies specific materials and semiconductor structures that utilize the disclosed technology, it will be readily understood that the systems, methods, and materials are equally applicable to several other structures that may benefit from aspects of the technology. Thus, the technology should not be considered limited to use with only the processes or materials described. Furthermore, while an exemplary chamber is described to provide a foundation for the technology, it should be understood that the technology may be applied to virtually any semiconductor processing chamber that is capable of the described operations.

[0019] FIG. 1 illustrates a top view of one embodiment of a deposition, etch, bake, and cure chamber processing system 100, according to an embodiment. In the figure, a pair of front-opening unified pods 102 supplies substrates of various sizes, which are received by a robot arm 104 and placed in a low-pressure holding area 106 before being placed in one of the substrate processing chambers 108a-108f located in tandem sections 109a-109c. A second robot arm 110 may be used to transport substrate wafers from the holding area 106 to the substrate processing chambers 108a-108f and vice versa. Each substrate processing chamber 108a-108f may be equipped to perform several substrate processing operations, including cyclical layer deposition, atomic layer deposition, chemical vapor deposition, physical vapor deposition, etching, precleaning, degassing, orientation, and other substrate processes, as well as the dry etching processes described herein.

[0020] 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 described processes may be performed in a chamber(s) separate from the illustrated fabrication system in different embodiments. It will be appreciated that additional configurations of deposition, etching, annealing, and curing chambers for dielectric films are contemplated by system 100.

[0021] 2A shows a cross-sectional view of an exemplary process chamber system 200 with a partitioned plasma generation region within the processing chamber. For example, during film etching of titanium nitride, tantalum nitride, metal, silicon, polysilicon, silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, etc., a process gas can be flowed through a gas inlet assembly 205 into a first plasma region 215. A remote plasma system 201 can optionally be included in the system to process a first gas, which then travels through the gas inlet assembly 205. The inlet assembly 205 can include two or more separate gas supply channels, and if a second channel (not shown) is included, the second channel can bypass the RPS 201.

[0022] A cooling plate 203, a faceplate 217, an ion suppressor 223, a showerhead 225, and a pedestal 265 or substrate support with a substrate 255 disposed thereon are shown, 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, and the heat exchange channels may be operated to heat and / or cool the substrate or wafer during processing operations. The wafer support platter of the pedestal 265, which may comprise aluminum, ceramic, or a combination thereof, may also be resistively heated using embedded resistive heater elements to achieve relatively high temperatures, such as up to or about 100° C. to greater than or about 1100° C.

[0023] The face plate 217 may be pyramidal, conical, or of another similar structure with a narrow top flaring to a wider base. The face plate 217 may also be flat, as shown, and may include multiple through channels used to distribute process gases. Depending on the use of RPS 201, plasma generating gases and / or plasma-excited species may pass through multiple holes, shown in FIG. 2B, in the face plate 217 for more uniform delivery to the first plasma region 215.

[0024] An exemplary configuration can include having a gas inlet assembly 205 opening into a gas feed region 258 separated from the first plasma region 215 by the faceplate 217 such that gases / species flow into the first plasma region 215 through holes in the faceplate 217. Structural and operational features can be selected to prevent significant backflow of plasma from the first plasma region 215 into the feed region 258, the gas inlet assembly 205, and the fluid feed system 210. The faceplate 217, i.e., the conductive top of the chamber, and the showerhead 225 are shown with an insulating ring 220 located between them, which allows an AC potential to be applied to the faceplate 217 relative to the showerhead 225 and / or ion suppressor 223. The insulating ring 220 can be located between the faceplate 217 and the showerhead 225 and / or ion suppressor 223, thereby allowing a capacitively coupled plasma to form 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 region.

[0025] The ion suppressor 223 may comprise a plate or other geometry defining a plurality of apertures throughout its structure, configured to suppress the transfer of ionic-charged species out of the first plasma region 215 while allowing uncharged neutral or radical species to pass through the ion suppressor 223 and into the activated gas delivery region between the suppressor and the showerhead. In embodiments, the ion suppressor 223 may comprise a porous plate with various aperture configurations. These uncharged species may include highly reactive species that are transported through the apertures with a less reactive carrier gas. As described above, the transfer of ionic species through the apertures may be reduced and, in some cases, completely suppressed. Controlling the amount of ionic species passing through the ion suppressor 223 may advantageously improve control over the gas mixture contacting the underlying wafer substrate, which in turn may improve control over the deposition and / or etching characteristics of the gas mixture. For example, adjusting the ion concentration of a gas mixture can significantly change its etch selectivity, e.g., SiNx:SiOx etch ratio, Si:SiOx etch ratio, etc. In alternative embodiments in which deposition is performed, the balance between conformal and flow-type deposition of the dielectric material may also be shifted.

[0026] The plurality of apertures in the ion suppressor 223 can be configured to control the passage of the activated gas, i.e., ionic, radical, and / or neutral species, through the ion suppressor 223. For example, the aspect ratio of the apertures, i.e., the diameter to length of the apertures, and / or the geometry of the apertures can be controlled to reduce the flow of ionic charged species in the activated gas passing through the ion suppressor 223. The apertures in the ion suppressor 223 can include a tapered portion facing the plasma excitation region 215 and a cylindrical portion facing the showerhead 225. The cylindrical portion can be shaped and sized to control the flow of ionic species passing into the showerhead 225. An adjustable electrical bias can be applied to the ion suppressor 223 as an additional means for controlling the flow of ionic species through the suppressor.

[0027] The ion suppressor 223 can function to reduce or eliminate the amount of ionic charged species that migrate from the plasma generation region to the substrate. Uncharged neutral and radical species can further pass through openings in the ion suppressor to react with the substrate. Note that in embodiments, complete elimination of ionic charged species in the reaction region around the substrate may not be performed. In some cases, ionic species are intended to reach the substrate to perform etching and / or deposition processes. In these cases, the ion suppressor can help control the concentration of ionic species in the reaction region at a level that is process-supportive.

[0028] Combining the showerhead 225 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 that could be damaged, misaligned, or otherwise distorted if directly contacted by the generated plasma. Furthermore, if the plasma is allowed to contact or approach the substrate level, the rate at which oxide species etch can increase. Therefore, if the exposed area of ​​material is an oxide, this material can be further protected by keeping the plasma away from the substrate.

[0029] The processing system may further include a power supply 240 electrically coupled to the processing chamber for supplying 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 depending on the process being performed. Such a configuration may enable the use of a tunable plasma in the process being performed. Unlike remote plasma units, which often present an on or off function, a tunable plasma may be configured to deliver a specific amount of power to the plasma region 215. This may enable the development of specific plasma characteristics, such as precursors being dissociated in a specific manner to enhance the etch profile created by those precursors.

[0030] 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. For example, a plasma can exist in the chamber plasma region 215 to create radical precursors from an inflow of fluorine-containing precursors or other precursors. To ignite a plasma in the chamber plasma region 215 during deposition, 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. The RF power source can generate a high RF frequency of 13.56 MHz, but can generate other frequencies alone or in combination with the 13.56 MHz frequency.

[0031] 2B shows a detailed view 253 of features that affect the distribution of process gas through the face plate 217. As shown in FIGS. 2A and 2B, the face plate 217, the cooling plate 203, and the gas inlet assembly 205 intersect to define a gas delivery region 258 into which process gas may be delivered from the gas inlets 205. Gas may fill the gas delivery region 258 and flow through apertures 259 in the face plate 217 to the first plasma region 215. The apertures 259 may be configured to direct flow substantially in one direction so that the process gas may flow into the processing region 233 but is partially or completely prevented from flowing back into the gas delivery region 258 after traversing the face plate 217.

[0032] Gas distribution assemblies such as showerhead 225 used in processing chamber section 200 may be referred to as dual channel showerheads and are further detailed in the embodiment depicted in Figure 3. Dual channel showerheads may provide etching processes that allow for separation of etchants outside of processing region 233, providing limited interaction with chamber components and each other before being delivered into the processing region.

[0033] The showerhead 225 may include an upper plate 214 and a lower plate 216. The plates may be coupled to one another to define a volume 218 between the plates. The coupling of the plates may 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 channel may be configured to provide fluid access from the volume 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 volume 218 between the plates and the second fluid channel 221. The volume 218 may be fluidically accessible through a side of the showerhead 225.

[0034] 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 variety of shapes and configurations to control and influence the flow of precursors through the showerhead 225. The small holes 375, which represent the second fluid channels 221, may be substantially uniformly distributed over the surface of the showerhead, even among the through-holes 365, and may help to provide more uniform mixing of the precursors as they exit the showerhead compared to other configurations.

[0035] The previously described chambers may be used in performing exemplary methods, including etching methods. Referring to FIG. 4 , exemplary operations in a method 400 according to an embodiment of the present technology are shown. Method 400 may include one or more operations prior to initiation of the method, including front-end processing, deposition, etching, polishing, cleaning, or any other operations that may be performed prior to the described operations. The method may include several optional operations that may or may not be particularly relevant to some embodiments of methods according to the present technology. For example, many of the operations are described to provide a broader scope of processes that may be performed, but are not critical to the technology or may be performed by alternative methodologies as described further below. Method 400 may be described with operations shown generally in FIGS. 5A-5D , which are described in conjunction with the operations of method 400. It should be understood that the figures illustrate 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.

[0036] Method 400 may or may not involve optional operations to develop the semiconductor structure for a particular manufacturing operation. It should be understood that method 400 may be performed on any number of semiconductor structures or substrates 505, including the exemplary structure on which a metal oxide removal operation may be performed, as shown in FIG. 5A . The exemplary semiconductor structure may include trenches, vias, or other recessed features that may include one or more exposed materials. For example, the exemplary substrate may include silicon or some other semiconductor substrate material, as well as an interlayer dielectric material in which a recess, trench, via, or isolation structure may be formed. The exposed material at any time during the etching process may be or include a metal material, one or more dielectric materials, a contact material, a transistor material, or any other material that may be used in semiconductor processing.

[0037] For example, FIG. 5A may show a substrate structure defining one or more trenches or recesses into which a metal oxide 510 material may be disposed. Substrate 505 may represent a dielectric material overlying one or more other structures on the substrate, and it should be understood that any number of materials may be formed beneath the structures shown. In some embodiments, the dielectric material may be or include silicon oxide, or any other oxide or nitride in which patterning may occur. While only two recesses containing metal oxides are shown, it should be understood that any number of recesses and instances may be formed, such as to create various patterns or structures to be processed. While the remainder of the disclosure refers to metal oxides, it should be understood that the present technology may encompass several metal oxide and / or nitride films. For example, metal oxides may include one or more transition metals, such as hafnium, zirconium, titanium, and other metals, such as aluminum. Materials may include combination compounds, such as hafnium zirconium oxide, as well as nitrides of any of these materials. Thus, the present technology is not limited to any particular metal oxide or metal nitride, but the compounds mentioned may be expressly encompassed by the present technology.

[0038] Embodiments of the present technology may involve performing a controlled anisotropic etching process to remove metal oxide material while maintaining the substrate structure relative to the substrate. While a mask material 515 may be included, conventional isotropic removal of metal oxide may cause undercutting in the substrate, which may be oxide material or other dielectric or silicon-containing materials. The present technology may limit or prevent isotropic removal by controlling the removal process to remove only deformed or damaged material, as described below. Thus, the etched structure may be defined by little or more undercutting, and exposed material may be etched, particularly in exposed vertical paths. In some embodiments encompassed by the present technology, the etching process may perform recesses that may be essentially or completely anisotropic.

[0039] It should be understood that the structures referred to are not limiting, and any of a variety of other semiconductor structures containing metal-containing materials or other metal-containing materials are similarly encompassed. Other exemplary structures may include two-dimensional and three-dimensional structures common in semiconductor fabrication, in which the present technology may selectively remove metal-containing materials relative to other exposed materials, such as silicon-containing materials and any of the other materials described elsewhere, resulting in the removal of metal-containing materials, such as metal oxides, relative to one or more other materials. Additionally, while high aspect ratio structures may benefit from the present technology, the technology may be equally applicable to lower aspect ratios and any other structures.

[0040] While method 400 may be performed, in embodiments, to remove exposed metal-containing materials, any number of oxides or metal-containing materials may be removed in any number of structures in embodiments of the present technology. The method may include specific operations for metal oxide removal. While the remaining disclosure routinely describes metal oxides, it should be understood that other metal oxides may be similarly processed by some embodiments of the present technology. In some embodiments, the method may include a multi-operation etch process that may control the etching of the metal oxide relative to other exposed materials, such as dielectric materials, e.g., silicon oxide, as well as any underlying materials, which may include dielectric or conductive materials used in the structure.

[0041] Method 400 may include, in optional operation 405, forming a plasma within a processing region of a semiconductor processing chamber. The substrate may already be positioned within the chamber prior to operation 405, as described above. Referring to chamber 200 merely for purposes of illustration, the plasma may be formed or generated in region 233 or within a region at least partially defined by the substrate support pedestal. Such a plasma is also understood to be a wafer-level plasma. Emissions of the plasma may be utilized in method 400, in operation 410, to modify the surface of an exposed material on a semiconductor substrate, such as the metal oxide material 510 described above. The substrate may be within or housed within the processing region of the semiconductor processing chamber.

[0042] The deformation operation of method 400 may enable controlled bombardment of metal oxide, causing the metal oxide structure, which may include previously annealed and denser oxide structures, to be amorphized to a certain depth within the structure. The generated plasma may be or include a bias plasma, which may be formed at a power sufficient to bombard the film and break bonds within the structure. Because the deformation operation may be performed directionally, only the mask material 515 and the metal oxide material 510 may be contacted by the plasma effluent, as shown in FIG. 5B, where oxygen and / or other ions 520 created within the plasma may be directed toward the substrate in a relatively straight path. Thus, the underlying substrate 505, including sidewalls that may be exposed during subsequent cycles, may be protected during process operations to remove the metal oxide.

[0043] The deformation operation 410 may involve an oxygen-containing gas and one or more other gases, which may include diatomic hydrogen or an inert gas such as helium, neon, argon, krypton, xenon, or radon. The material used to create the plasma may also be an additional material or precursor that may have limited chemical activity or may be unreactive with the exposed material on the semiconductor surface being modified. By utilizing an oxygen-containing gas, such as diatomic oxygen, nitrous oxide, water, ozone, or other oxygen-containing material, material bonds may be broken or amorphized within the film to a depth of penetration, which may be controlled based on the bias power. Oxygen radicals may also react with and remove oxygen within the film, which may create a more porous structure during the deformation operation. Additional gases, such as hydrogen and / or helium, may be provided along with one or more oxygen-containing materials, which may affect the nature of the deformation or damage operation. For example, hydrogen, being a small and light material, may be less likely to sputter the material it is aimed at than a heavier material, resulting in deeper penetration into the film. For helium, being a heavier material, adding helium may increase the bond breaking and release of oxygen within the film. In addition to amorphizing the film, the remaining material may become more porous, facilitating volume expansion in subsequent steps. The remaining material may also become more reactive, creating more dangling bonds in the deformation process.

[0044] Process conditions can also facilitate deformation. For example, a plasma formed from oxygen gas can be a bias plasma, providing a directional flow of plasma effluents toward the substrate. The plasma can be a low-level plasma to limit the amount of bombardment, sputtering, and surface deformation. In embodiments, the plasma power can be less than or about 500 W, less than or about 450 W, less than or about 400 W, less than or about 350 W, less than or about 300 W, less than or about 250 W, less than or about 200 W, or even less. For example, by utilizing a plasma power of about 300 W or less, the penetration depth of plasma effluents can be controlled to limit sidewall interaction or damage to the underlying structure. For example, the described deformation operations may allow the surface of exposed material on a semiconductor substrate to be deformed to a depth of less than or about 20 nm from the exposed surface within the semiconductor substrate, and may allow deformation of the surface of the material to a depth of less than or about 18 nm, less than or about 16 nm, less than or about 16 nm, less than or about 14 nm, less than or about 12 nm, less than or about 10 nm, less than or about 9 nm, less than or about 8 nm, less than or about 7 nm, less than or about 6 nm, less than or about 5 nm, or less.

[0045] The deformation operation may be relatively or completely insensitive to temperature, and in embodiments, the temperature may be maintained at any of the temperatures described below for the plasma operation. The pressure within the processing chamber may also be controlled during the deformation operation 410. For example, while forming the inert plasma and performing the deformation operation, the pressure within the processing chamber may be maintained at less than or about 1 Torr. Furthermore, in some embodiments, the pressure within the processing chamber may be maintained at less than or about 750 mTorr, less than or about 600 mTorr, less than or about 500 mTorr, less than or about 400 mTorr, less than or about 300 mTorr, less than or about 250 mTorr, or even less. The pressure within the chamber may affect the directionality of the deformation operation 410 by affecting the mean free path of the radical material created. For example, when pressure is increased, the deformation process may become more isotropic due to increased collisions that can cause scattering, and when pressure is reduced, the deformation process may become more anisotropic as the mean free path increases, which allows for the improved directionality provided by the bias. Thus, as pressure is increased, the underlying material also begins to be treated, which, after removal, can remove material beyond what was originally desired in some operations.

[0046] After the surface modification of the metal oxide film, a removal process can be performed, which can include two-part removal. Method 400 can include flowing a halogen-containing precursor, including a first halogen-containing precursor, into a semiconductor processing chamber housing the substrate described. The halogen-containing precursor can be plasma-enhanced in some embodiments, such as in optional operation 415. The halogen-containing precursor can be flowed through a remote plasma region of the processing chamber, such as region 215 described above, and a plasma can be formed from the halogen-containing precursor to create plasma effluents. While a substrate-level plasma can be created, in some embodiments, the plasma can be a remote plasma, which can protect exposed substrate material from ion bombardment that can occur with a substrate-level plasma. When the plasma is formed, the plasma power of the capacitively coupled plasma or other formed plasma can be maintained at or below any of the previously mentioned plasma power levels. Furthermore, in some embodiments, the first halogen-containing precursor may not be plasma-enhanced, such as by utilizing hydrogen fluoride, which can be flowed directly into the processing region of the chamber.

[0047] Whether plasma-enhanced or not, in operation 420, plasma effluents of the halogen-containing precursor or first halogen-containing precursor may be delivered to a substrate processing region, where the effluents may contact a semiconductor substrate containing damaged or amorphized metal-containing material in operation 425, as shown in FIG. 5C. Fluorine material 525, which may be fluorine ions as well as additional ions such as hydrogen ions, as mentioned below, may be flowed into the processing region to interact with the substrate. Due to the porous nature of the amorphized portion of the metal oxide material, fluorine radicals or material may be incorporated into the porous or damaged structure and diffuse throughout the structure to the level of deformation performed. The amorphous structure may more readily accept the fluorine material, which may result in a volume expansion of the deformed portion of the metal oxide material. Contacting may create a fluorinated material, such as a metal oxyfluoride or metal oxide halide material, such as by converting exposed metal oxide on the substrate. In some embodiments, after fluorination, the plasma may be extinguished and the chamber may be purged. Because the metal oxyfluoride material may not be volatile at chamber operating conditions, additional operations may be performed to cause the amorphized and fluorinated portions to be removed. Furthermore, because the fluorination may not penetrate to the underlying metal oxide or untransformed portions of the metal oxide, the amount of removal may be limited to the depth of the transformed material.

[0048] After the fluorination operation, an etchant precursor may be flowed into the processing region in operation 430. In some embodiments, the etchant precursor may be a second halogen-containing precursor, which may contain the same or a different halogen as the first halogen-containing precursor. The etchant precursor may be volatile under processing conditions and may interact with the fluorinated metal oxide or other oxide material to create metal and / or oxygen byproducts that may be released from the substrate. Thus, the etchant precursor may contact the fluorinated material in operation 435 and perform a ligand exchange with the fluorine in the material, which may create volatile byproducts that may be released from the substrate. By performing two removal operations according to embodiments of the present technique, controlled removal of the transformed material may be performed, which may preserve the underlying material as well as the substrate material. As shown in FIG. 5D, a second halogen precursor 530 may be delivered, which may form a ligand exchange with the fluorinated metal oxide. Thus, metal by-products 535, which may include metal chlorides, metal oxychlorides, or other materials containing one or more of metal, oxygen, fluorine, hydrogen, and chlorine, may be liberated from the substrate, which may expose the underlying metal oxide or substrate material. The method may be repeated any number of cycles to continue removing the metal oxide in unobtrusive layers. This may create controlled removal based on the depth of deformation, which may allow some or all of the formed metal oxide material to be removed from the substrate in accordance with embodiments of the present technology.

[0049] The second halogen precursor may also be plasma-enhanced, although in some embodiments the second precursor may not be plasma-enhanced, and in some embodiments the semiconductor processing chamber may be maintained plasma-free during delivery and operation utilizing the second halogen precursor. By utilizing certain precursors and performing etching within certain process conditions, plasma-free removal may be performed, which may also be dry etching. Thus, techniques according to aspects of the present technology may be performed to remove metal oxide from any number of features, including high aspect ratio features and thin dimensions that may otherwise be unsuitable for wet etching or reactive ion etching.

[0050] The precursors in each of the two-step removal operations may include a halogen-containing precursor, and in some embodiments, may include one or more of fluorine or chlorine. Some exemplary precursors that may be utilized as the first precursor include hydrogen fluoride, nitrogen trifluoride, or halides, including any organic fluorides. Precursors may also be co-flowed in various combinations. In some embodiments, nitrogen trifluoride or some other fluorine-containing precursor may be delivered to the remote plasma region along with hydrogen and plasma-enhanced to create a fluorinated surface of the metal oxide in the first operation. The etchant precursor utilized as the second halogen precursor may be or include a chlorine-containing precursor, such as boron trichloride, titanium tetrachloride, or any other chlorine-containing material. Furthermore, in some embodiments, chlorine radical materials may be generated, such as in a plasma process performed locally or remotely, which may deliver the chlorine radical materials to interact with the fluorinated moieties of the metal oxide. Under the processing conditions of the present technology, these chlorine-containing materials may facilitate the formation of volatile byproducts that can remove the fluorinated metal oxide. For example, some by-products include metal oxychlorides or metal chlorides, which may be volatile under processing conditions, which may facilitate removal of material from the substrate.

[0051] The processing conditions can affect and facilitate etching by the present technology. Because the etching reaction can proceed based on the thermal dissociation of the halogen for the second reaction between the second halogen precursor and the fluorinated oxide material, the temperature can depend at least in part on the specific halogen or precursor to initiate dissociation. For example, when the temperature increases to above or about 100°C or above or about 150°C, etching can begin to occur or increase, which can indicate the dissociation of the precursor and / or the activation of the reaction with the metal oxyfluoride. As the temperature continues to increase, dissociation can become more readily, as can the reaction with the fluorinated metal oxide.

[0052] Thus, in some embodiments of the present technology, etching methods can be performed at substrate, pedestal, and / or chamber temperatures greater than or about 100°C, greater than or about 150°C, greater than or about 200°C, greater than or about 250°C, greater than or about 300°C, greater than or about 350°C, greater than or about 400°C, greater than or about 450°C, or even higher temperatures. Temperatures can also be maintained at any temperature within these ranges, within smaller ranges encompassed by these ranges, or between any of these ranges. In some embodiments, methods can be performed on substrates that may have several formed features that can create a thermal balance. Additionally, a first etchant operation, such as one including a fluorine-containing precursor, can be performed at a temperature less than the temperature of a second etchant operation. For example, during delivery of the fluorine material, the substrate temperature can be maintained at less than or about 300° C., less than or about 250° C., less than or about 200° C., less than or about 150° C., less than or about 100° C., or even lower, which can limit reactive etching of other materials on the substrate while allowing fluorination to occur in the amorphized regions of the metal oxide. The temperature can then be raised to any of the temperature ranges mentioned above for the second operation, such as greater than or about 300° C., or the substrate can be transferred to a second chamber maintained at a higher temperature for the chlorination operation.

[0053] The pressure in the chamber can also affect the operations performed and the temperature at which the halogen dissociates from the transition metal for the second removal operation. To facilitate fluorination, which may be based on plasma-enhanced precursors, the process pressure can be lower than that in the second removal operation, which may be thermally based in some embodiments. Maintaining a lower pressure in the first operation, such as during use of the first halogen precursor, can facilitate increased interaction at the substrate surface. Lower pressure during the first part of the method can increase the mean free path between atoms, as explained above, which can increase energy and interaction at the film surface. While utilizing a higher pressure in the second part of the method, such as during use of the second halogen precursor, can increase the etch rate, in some embodiments, the pressure can be maintained or reduced to any of the pressures mentioned elsewhere prior to the second removal operation. Thus, in some embodiments, the pressure may be maintained at less than about 20 Torr during a first portion of the etch, such as during operations 405-415, and the pressure may be maintained at less than or about 15 Torr, less than or about 10 Torr, less than or about 9 Torr, less than or about 8 Torr, less than or about 7 Torr, less than or about 6 Torr, less than or about 5 Torr, less than or about 4 Torr, less than or about 3 Torr, less than or about 2 Torr, less than or about 1 Torr, less than or about 0.5 Torr, or less.

[0054] The pressure may then be maintained, reduced, or increased during a second portion of the method, such as during operations 420-425. When the pressure is increased, the pressure may be maintained at greater than or about 1 Torr, greater than or about 5 Torr, greater than or about 10 Torr, greater than or about 15 Torr, greater than or about 20 Torr, greater than or about 25 Torr, greater than or about 30 Torr, greater than or about 35 Torr, greater than or about 40 Torr, greater than or about 45 Torr, greater than or about 50 Torr, greater than or about 75 Torr, greater than or about 100 Torr, or higher, which may extend up to atmospheric pressure, although in some embodiments, vacuum conditions may facilitate operation. The pressure can also be maintained at any pressure within these ranges, any pressure within the smaller ranges encompassed by these ranges, or any pressure between any of these ranges.

[0055] As previously mentioned, in some embodiments, hydrogen may be delivered with nitrogen trifluoride or the first halogen precursor during the first removal operation. By including hydrogen, the etch rate of the material from fluorine may be reduced or inhibited during fluorination. To protect underlying materials adjacent to the metal fluoride to be removed, hydrogen may be delivered at a flow rate that exceeds the flow rate of the first halogen-containing precursor. For example, in some embodiments in which the first halogen-containing precursor can be nitrogen trifluoride, the flow ratio of hydrogen to nitrogen trifluoride can be greater than or about 1.5:1, and the flow ratio of hydrogen to nitrogen trifluoride can be greater than or about 2.0:1, greater than or about 2.0:1, greater than or about 2.5:1, greater than or about 3.0:1, greater than or about 3.0:1, greater than or about 3.5:1, greater than or about 4.0:1, greater than or about 4.5:1, greater than or about 5.0:1, greater than or about 10.0:1, or even higher. The hydrogen radicals can help passivate other exposed materials while the fluorine interacts with the amorphized metal oxide material within the feature.

[0056] By utilizing materials according to embodiments of the present technology, controlled, directional removal of metal oxides can be performed. Performing a highly directional deformation operation can enable a controlled removal operation that can be selective to amorphized material relative to other materials on the substrate. The previously described methods can enable removal of metal oxides or other oxide materials relative to some other exposed material. By utilizing a multi-precursor etchant process as previously described, improved etching of metal oxides can be performed, which can both increase selectivity over conventional techniques as well as improve etch access in small pitch features.

[0057] 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 some embodiments may be practiced without some of these details or with additional details.

[0058] Although several embodiments have been disclosed, it will be recognized by those skilled in the art that various modifications, alternative configurations, and equivalents may be used without departing from the spirit of the embodiments. Moreover, to avoid unnecessarily obscuring the present technology, some well-known processes and elements have not been described. Therefore, the above description should not be taken as limiting the scope of the present technology. Furthermore, while a method or process may be described sequentially or stepwise, it should be understood that operations may be performed simultaneously or in an order different from the order listed.

[0059] Where a range of values ​​is provided, unless the context clearly dictates otherwise, it is understood that each intervening value between the upper and lower limits of that range, to the smallest fraction of the unit of the lower limit, is also specifically disclosed. 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 encompassed. The upper and lower limits of those smaller ranges may independently be included or excluded in the range, and each range in which either limit is included, neither limit is included, or both limits are included in the smaller range is also encompassed within the technology, subject to any explicitly excluded limit in the stated range. When a stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included.

[0060] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, a reference to "a precursor" includes a plurality of such precursors, a reference to "the precursor" includes a reference to one or more precursors and equivalents thereof known to those skilled in the art, and so forth.

[0061] Also, as used in this specification and the following claims, the words "comprise(s)," "comprising," "contain(s)," "containing," "include(s)," and "including" specify the presence of stated features, integers, components, or operations, but they do not exclude the presence or addition of one or more other features, integers, components, operations, acts, or groups.

Claims

1. modifying an exposed surface of a layer of metal oxide on a substrate contained in a processing region of a semiconductor processing chamber to create a modified portion of metal oxide, wherein modifying the exposed surface of the layer of metal oxide includes: forming a plasma of an oxygen-containing precursor to produce an oxygen-containing plasma effluent; directing the oxygen-containing plasma effluents toward the exposed surface of the layer of metal oxide, the oxygen-containing plasma effluents causing portions of the metal oxide to become amorphous metal oxide; modifying the exposed surface of the layer of metal oxide, contacting the transformed portion of the metal oxide with a fluorine-containing precursor, wherein the contacting produces a metal oxyfluoride material; flowing an etchant precursor into the processing region; contacting the metal oxyfluoride material with the etchant precursor; removing the metal oxyfluoride material; and An etching method comprising:

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

3. The etching method of claim 1 , wherein the fluorine-containing precursor comprises hydrogen fluoride or a plasma-enhanced fluorine-containing precursor.

4. 4. The etching method of claim 3, wherein the plasma-enhanced fluorine-containing precursor is formed in a remote plasma region of the semiconductor processing chamber.

5. 10. The etching method of claim 1, wherein the plasma of the oxygen-containing precursor is formed at a plasma power greater than or equal to 100 W in the processing region.

6. 10. The etching method of claim 1, wherein the semiconductor processing chamber is maintained plasma-free while flowing the etchant precursor into the processing region.

7. 10. The etching method of claim 1, wherein the temperature within the semiconductor processing chamber is elevated prior to contacting the metal oxyfluoride material with the etchant precursor.

8. 10. The etching method of claim 1, wherein a pressure in the semiconductor processing chamber is maintained less than or equal to 5 Torr while flowing the fluorine-containing precursor.

9. 10. The etching method of claim 8, wherein a pressure in the semiconductor processing chamber is maintained greater than or equal to 15 Torr while flowing the etchant precursor into the processing region.

10. modifying an exposed surface of a layer of metal-containing material on a substrate contained in a processing region of a semiconductor processing chamber to create a modified portion of metal-containing material, wherein modifying the exposed surface of the layer of metal-containing material includes: forming a plasma of an oxygen-containing precursor to produce an oxygen-containing plasma effluent; directing the oxygen-containing plasma effluents toward the exposed surface of the layer of metal-containing material, the oxygen-containing plasma effluents causing portions of the metal-containing material to become an amorphous metal oxide; modifying the exposed surface of the layer of metal-containing material, flowing a first halogen-containing precursor into a remote plasma region of the semiconductor processing chamber while striking a plasma to create plasma effluents; contacting the transformed portion of the metal-containing material with the plasma effluents, wherein the contacting creates a metal fluoride material; and flowing a second halogen-containing precursor into the treatment region; contacting the metal fluoride material with the second halogen-containing precursor; removing said metal fluoride material; An etching method comprising:

11. 11. The etching method of claim 10, wherein the first halogen-containing precursor comprises fluorine, the second halogen-containing precursor comprises boron trichloride, and the metal-containing material comprises an oxide or nitride containing aluminum, hafnium, zirconium, or titanium.

12. 11. The etching method of claim 10, further comprising terminating plasma formation prior to flowing the second halogen-containing precursor.

13. The etching method of claim 10 , wherein contacting the transformed portion of metal-containing material with the plasma effluents is carried out at a first temperature.

14. 14. The etching method of claim 13, wherein contacting the metal fluoride material with the second halogen-containing precursor is carried out at a second temperature greater than the first temperature.

15. the first halogen-containing precursor comprises nitrogen trifluoride, and the method comprises: flowing hydrogen with said first halogen-containing precursor; The etching method of claim 10 further comprising:

16. 16. The etching method of claim 15, wherein the flow rate of the hydrogen is at least twice the flow rate of the first halogen-containing precursor.

17. forming a plasma of an oxygen-containing precursor to produce an oxygen-containing plasma effluent; directing the oxygen-containing plasma effluents at a layer of metal oxide on a substrate housed in a processing region of a semiconductor processing chamber to create transformed portions of the metal oxide, the oxygen-containing plasma effluents causing portions of the metal oxide to become amorphous metal oxide; flowing a fluorine-containing precursor into a remote plasma region of the semiconductor processing chamber while striking a plasma in the remote plasma region to create plasma effluents; contacting the transformed portion of the metal oxide with the plasma effluents, wherein the contacting produces a metal oxyfluoride material; and flowing a chlorine-containing precursor into the treatment region; contacting the metal oxyfluoride material with the chlorine-containing precursor; removing the metal oxyfluoride material; and An etching method comprising:

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