Removal of Tin Oxide in Chamber Cleaning

Abstract

[Solution] Tin oxide deposits in a process chamber are cleaned by a method that includes forming a volatile tin-containing compound by exposing the tin oxide to a mixture containing hydrogen (H) in a plasma and a hydrocarbon, followed by removing the carbon-containing polymer formed as a result of the hydrocarbon exposure. The carbon-containing polymer can be removed by exposing the carbon-containing polymer to an oxygen-containing reactant (e.g., O in a plasma) or H in the absence of the hydrocarbon. These steps are repeated as many times as necessary to clean the process chamber. The method can be used to clean ALD, CVD, and PVD process chambers and is particularly useful for cleaning at relatively low temperatures below about 120°C.

Description

Technical Field

[0001] (Incorporation by reference) As part of this application, a PCT application form is filed simultaneously with this specification. Each application specified in this simultaneously filed PCT application form and for which this application claims benefit or priority is incorporated by reference in its entirety herein for all purposes.

[0002] The present invention relates to a method and an apparatus for cleaning a process chamber. Specifically, embodiments of the present invention relate to the removal of tin oxide deposits from a process chamber used in semiconductor device manufacturing.

Background Art

[0003] In semiconductor device fabrication, deposition techniques and etching techniques are used for patterning materials, such as the formation of metal lines embedded in a dielectric layer. Examples of deposition techniques include atomic layer deposition (ALD), chemical vapor deposition (CVD), and physical vapor deposition (PVD). Examples of etching techniques include wet etching methods and dry etching methods such as reactive ion etching (RIE).

[0004] Dry deposition and dry etching methods are typically performed in a process chamber having a substrate support for holding a semiconductor substrate in a predetermined position during deposition or etching, and an inlet (e.g., a showerhead) for introducing one or more process gases into the process chamber. The deposition and etching apparatus may also include a system for generating plasma either directly in the process chamber that houses the substrate or upstream of the process chamber. The process chamber can be cleaned periodically to remove deposits of materials (such as from the chamber walls and showerhead) from the chamber.

[0005] The description of the background art provided in this specification is for presenting the background of the present disclosure generally. The achievements of the inventors named herein within the scope described in this background art, as well as aspects of the description that cannot be regarded as prior art at the time of filing, are not recognized as prior art for the present disclosure, either explicitly or implicitly.

Summary of the Invention

Problems to be Solved by the Invention

[0006] A method and apparatus for removing tin oxide deposits from a process chamber are provided. The method is particularly useful for cleaning tin oxide at relatively low temperatures (e.g., temperatures below about 140°C such as temperatures of about 30 to 120°C), but can also be used at higher temperatures. The method can be used for removing tin oxide in various process chambers including, but not limited to, ALD process chambers (including plasma-enhanced ALD process chambers), CVD process chambers (including plasma-enhanced CVD process chambers), and PVD process chambers.

Means for Solving the Problems

[0007] In one aspect, a method for cleaning a process chamber is provided, the method comprising: (a) providing a process chamber having a layer of tin oxide on at least some parts of the process chamber; (b) exposing the tin oxide layer in the process chamber to a process gas comprising a hydrocarbon and hydrogen (H2) to convert at least a portion of the tin oxide layer to a volatile compound, wherein the exposure of the tin oxide layer to the process gas comprising a hydrocarbon and hydrogen (H2) further results in the formation of a non-volatile carbon-containing polymer, and optionally purging the process chamber; and (c) removing the carbon-containing polymer by exposing the carbon-containing residue to an oxygen-containing reactant or H2, wherein the exposure to H2 is carried out in the absence of a hydrocarbon. Including. The method may also include repeating steps (b) and (c) alternately.

[0008] In one embodiment, the carbon-containing polymer is removed by exposing the carbon-containing residue to an oxygen-containing reactant. Examples of oxygen-containing reactants include, but are not limited to, O2, O3, and H2O2. In one embodiment, the oxygen-containing reactant is plasma-activated O2. In another embodiment, the oxygen-containing reactant is O3.

[0009] In another embodiment, the carbon-containing polymer is removed by exposing the carbon-containing residue to a process gas consisting essentially of H2 from the plasma or consisting essentially of a mixture of H2 and an inert gas.

[0010] The removal of the carbon-containing polymer in some embodiments is carried out while the process chamber is heated.

[0011] In some embodiments, the process chamber includes metal parts such as aluminum parts, which are cleaned by the provided method.

[0012] In another aspect, an apparatus for processing a semiconductor substrate is provided, the apparatus including a process chamber having an inlet for introducing a process gas and a controller having program instructions for cleaning the process chamber from an indium tin oxide layer. In one embodiment, the program instructions are configured to cause: (i) an exposure of the indium tin oxide layer in the process chamber to a process gas containing a hydrocarbon and hydrogen (H2) to convert at least a portion of the indium tin oxide layer to a volatile compound, the exposure of the indium tin oxide layer to the process gas containing a hydrocarbon and hydrogen (H2) further resulting in the formation of a non-volatile carbon-containing polymer, and (ii) a removal of the carbon-containing residue by exposing the carbon-containing polymer to an oxygen-containing reactant (e.g., at least one of O2, O3, and H2O2), the exposure to H2 being performed in the absence of a hydrocarbon. In one embodiment, the apparatus further includes a system for generating a plasma. In some embodiments, the program instructions for (ii) are configured to cause an exposure of the carbon-containing polymer to plasma-activated O2. In some embodiments, the apparatus further includes a heater. In some embodiments, the program instructions for (ii) are configured to cause an exposure of the carbon-containing polymer to plasma-activated O2 in a heated process chamber. In some embodiments, the program instructions are further configured to repeat steps (i) and (ii). In another aspect, the controller includes a program.

[0013] In another aspect, a computer machine-readable medium is provided, the medium including code for performing any of the methods described herein.

[0014] In another aspect, a method for etching a tin oxide layer on a semiconductor substrate is provided, the method comprising: (a) providing a semiconductor substrate having an exposed layer of tin oxide; (b) contacting the exposed tin oxide layer in a process chamber with a process gas comprising a hydrocarbon and hydrogen (H2) to convert at least a portion of the tin oxide layer to a volatile compound, wherein contacting the tin oxide layer with the process gas comprising a hydrocarbon and hydrogen (H2) further results in the formation of a non-volatile carbon-containing polymer; and (c) removing the carbon-containing polymer by exposing the carbon-containing polymer to an oxygen-containing reactant or H2, wherein the exposure to H2 is carried out in the absence of a hydrocarbon. In some embodiments, the method further comprises coating a photoresist on the semiconductor substrate, exposing the photoresist, patterning the photoresist to transfer the pattern to the semiconductor substrate, and selectively removing the photoresist from the semiconductor substrate.

[0015] In some embodiments, the method further comprises depositing tin oxide on the semiconductor substrate (which may also include deposition on the process chamber) using a tin-containing precursor selected from the group consisting of: SnF2, SnCl4, SnBr4, SnH4, tetraethyltin (SnEt4), tetramethyltin (SnMe4), tetrakis(dimethylamino)tin (Sn(NMe2)4), tetrakis(diethylamino No )tin (Sn(NEt2)4), tetrakis(ethylmethylamino)tin (Sn(NMeEt)4), (dimethylamino)trimethyltin(IV) (Me3Sn(NMe2)), dibutyltin diacetate (Bu2Sn(OAc)2), Sn(II)(1,3-bis(1,1-dimethylethyl)-4,5-dimethyl-(4R,5R)-1,3,2-diazastannolidine-2-ylidene), N 2 ,N 3 -di-tert-butyl-butane-2,3-diamino-tin(II), bis[bis(trimethylsilyl)amino]tin(II)

Chemical formula

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[0016] In some embodiments, the tin-containing precursor is an organotin precursor selected from the group consisting of tetramethyltin, tetrakis(dimethylamino)tin, and (dimethylamino)trimethyltin(IV).

[0017] The aspects and other aspects regarding the embodiments of the subject matter described herein are set forth in the accompanying drawings and the following description.

Brief Description of the Drawings

[0018]

Figure 1

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Figure 2

[0020]

Figure 3A

Figure 3B

Figure 3C

Figure 3D

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Figure 4

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Figure 5

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[0026] A method and apparatus for cleaning tin oxide from a process chamber are provided. The method provided can be used for removing tin oxide deposits in various process chambers including ALD process chambers such as plasma enhanced ALD (PEALD) process chambers, CVD process chambers such as plasma enhanced CVD (PECVD) process chambers, and PVD process chambers.

[0027] Tin oxide, as used herein, generally refers to a compound of tin and oxygen having the stoichiometry of SnO2. Tin oxide layers and deposits that can be cleaned by the method provided contain, in some instances, at least 90 wt% SnO2, such as at least 95 wt% SnO2.

[0028] Tin oxide is a versatile material that can be used as a spacer or mandrel, for example, during patterning in semiconductor device manufacturing. Tin oxide can be deposited on a semiconductor substrate by ALD, CVD, or PVD methods and can also deposit unintentionally on the inner parts of a process chamber such as chamber walls and showerheads. Cleaning tin oxide deposits in a process chamber presents several problems, which may involve damage to process chamber components or incomplete removal of tin oxide.

[0029] The method provided herein can be used to remove tin oxide deposits from various chamber surfaces, such as from a metal chamber surface (e.g., from an aluminum chamber surface), without damaging the surface. Since chlorine-based chemistry can damage the metal chamber walls (e.g., aluminum chamber walls) during tin oxide removal, the method is not inferior compared to chlorine-based cleaning methods. Hydrogen-based cleaning chemistry causes powder formation in the process chamber due to the decomposition of by-products, so the provided method is also not inferior compared to H2-based etching.

[0030] Tin oxide can be removed (converted to volatile compounds) by exposing the tin oxide layer to a mixture of H2 and a hydrocarbon (e.g., CH4) with plasma activation. However, it has been found that this cleaning chemistry can lead to the formation of a non-volatile carbon-containing polymer on the surface of the tin oxide layer, and the polymer hinders tin oxide etching and results in incomplete removal of tin oxide. The provided method addresses this problem by periodically removing the carbon-containing polymer during tin oxide removal. The formation of the carbon-containing polymer is particularly prominent at relatively low temperatures (e.g., temperatures below about 140 °C). Therefore, the provided method is particularly useful at low temperatures and can be carried out at temperatures below about 140 °C, such as below about 120 °C, for example, about 30 - 120 °C or 80 - 120 °C, where the temperature is measured at the substrate support. The term "about", when used with reference to a numerical value, includes the range of ± 10% of the stated numerical value, unless otherwise specified.

[0031] Figure 1 is a process flow diagram showing an embodiment of a tin oxide cleaning method. The process begins in step 101 by providing a process chamber having a tin oxide layer. The tin oxide layer may remain on various parts of the chamber, such as on the chamber walls, on the showerhead, or on the substrate support. The process chamber may be a deposition process chamber (e.g., an ALD, CVD, or PVD process chamber) that was used to deposit tin oxide on a semiconductor substrate (e.g., a wafer). In one example, when tin oxide is deposited on a semiconductor substrate by exposing the semiconductor substrate to a tin-containing precursor and an oxygen-containing precursor (e.g., within an ALD or CVD chamber), tin oxide deposits are formed on the chamber walls. Exemplary tin-containing precursors include organotin precursors such as tetraethyltin (SnEt4), tetramethyltin (SnMe4), tetrakis(dimethylamino)tin (Sn(NMe2)4), tetrakis(diethylamino) No )tin (Sn(NEt2)4), tetrakis(ethylmethylamino)tin (Sn(NMeEt)4), (dimethylamino)trimethyltin(IV) (Me3Sn(NMe2)), dibutyltin diacetate (Bu2Sn(OAc)2), Sn(II)(1,3-bis(1,1-dimethylethyl)-4,5-dimethyl-(4R,5R)-1,3,2-diazastannolidine-2-ylidene), N 2 ,N 3 -di-tert-butyl-butane-2,3-diamino-tin(II), and the like. Additional examples of organotin precursors include: bis[bis(trimethylsilyl)amino]tin(II) [Chemical formula] (wherein TMS is trimethylsilyl), dibutyldiphenyltin [Chemical formula] hexaphenylditin(IV) [Chemical formula] Tetraallyltin

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[0032] In another example, the tin-containing precursor can also be an inorganic tin precursor such as tin halide (e.g., SnF2, SnCl4, SnBr4), tin hydride (e.g., SnH4). In some embodiments, trimethyltin chloride

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[0033] Examples of oxygen-containing precursors include, but are not limited to, oxygen (O2), ozone (O3), hydrogen peroxide (H2O2), and the like. When preparing the chamber for cleaning, the semiconductor substrate is removed from the process chamber.

[0034] A schematic view of a portion of a process chamber having a tin oxide deposit is shown in FIG. 3A. The portion of the process chamber 301 may be made of any suitable chamber material such as a metal (e.g., aluminum). In a particular example, the portion of the process chamber 301 is part of the aluminum chamber wall of an ALD process chamber. The tin oxide layer 303 is typically formed on a portion of the process chamber 301 after sequential tin oxide depositions have been performed on several semiconductor substrates. In some embodiments, the tin oxide layer 303 has a thickness of about 0.5 to 10 μm.

[0035] Referring to the process flow diagram of FIG. 1, the cleaning process then, in step 103, exposes the process chamber to a process gas containing H2 and a hydrocarbon to convert at least a portion of the tin oxide into a volatile compound while forming a carbon-containing polymer. In some embodiments, the process gas is activated in a plasma. In one example, a mixture of H2 and a hydrocarbon (e.g., methane, ethane, propane, cyclopropane, or butane) is introduced into the process chamber and activated with plasma to react with the tin oxide layer. At least a portion of the tin oxide is etched by being converted into a volatile compound that can be easily removed from the process chamber, but a non-volatile carbon-containing polymer is formed under certain conditions (e.g., a temperature of less than about 140°C). The resulting structure is illustrated in FIG. 3B. FIG. 3B shows that the thickness of the tin oxide layer 303 is reduced after the etching step, but a layer 305 of the carbon-containing polymer is formed covering the tin oxide layer 303. The carbon-containing polymer layer 305 prevents further etching of the tin oxide layer 303 by the mixture of hydrogen and hydrocarbon. In some embodiments, the tin oxide etching step 103 removes about 0.1 to 0.25 μm of tin oxide.

[0036] Next, in step 105, in the absence of hydrocarbons, the carbon-containing polymer is removed by exposing the carbon-containing polymer to an oxygen-containing reactant or H2. Both the oxygen-containing reactant and H2 can convert the carbon-containing polymer into volatile compounds. For example, the oxygen-containing reactant may convert the carbon-containing polymer into CO2 and / or CO. Examples of oxygen-containing reactants include dioxygen (O2), ozone (O3), and hydrogen peroxide (H2O2). This step may be carried out thermally (in the absence of plasma) or using plasma activation. For example, plasma-activated O2 may be used for the removal of the carbon-containing polymer. In other embodiments, ozone or hydrogen peroxide is used for the removal of the carbon-containing polymer without using plasma activation. When H2 is used for the removal of the carbon-containing polymer, H2 is introduced into the process chamber without using hydrocarbons. For example, a gas consisting essentially of H2 (with or without an inert gas diluent) may be used, in which case the reaction with the carbon-containing polymer may optionally be assisted by plasma. The structure formed after the removal of the carbon-containing polymer is shown in FIG. 3C. In the illustrated embodiment, it is shown that a portion of the tin oxide layer 303 remains on a portion of the chamber 301. In some embodiments, it will be understood that one cycle, including one tin oxide removal step 103 and one carbon-containing polymer removal step 105, may be sufficient for chamber cleaning if the initial tin oxide layer is thin. However, for thicker tin oxide layers, one cycle may be insufficient and multiple cycles are carried out.

[0037] In one cycle including one step 105 following one step 103, if it is insufficient to remove all the tin oxides, as shown in step 107, steps 103 and 105 are repeated. In some embodiments, steps 103 and 105 are repeated multiple times until all the tin oxides are removed from the surface of the process chamber. In some embodiments, the cleaning process includes performing about 4 to 10 cycles, and each cycle includes one tin oxide removal step 103 and one carbon-containing polymer removal step 105. The structure obtained after multiple cycles is shown in FIG. 3D. In the figure, the tin oxide layer 303 has been completely removed from a portion of the process chamber 301.

[0038] Note that the process chamber may be purged after each of steps 103 and 105 to remove volatile reaction products. For example, the purge can be performed using an inert gas such as N2, helium, argon, etc.

[0039] Figure 2 is a process flow diagram showing an example of an embodiment of the cleaning method. In step 201, a process chamber having a tin oxide layer is provided. In a specific example, the process chamber is a PEALD process chamber. In step 203, the process chamber is exposed to a plasma formed in a process gas containing a hydrocarbon and H2 to convert at least a part of the tin oxide layer into a volatile compound and at the same time form a carbon-containing polymer. In one embodiment, the molar ratio of H2 to the hydrocarbon (e.g., CH4) is about 1 to 20 (and in some embodiments is about 1:15 to 1:25). Hydrogen and the hydrocarbon are introduced together with an inert carrier gas such as Ar, He, or N2 in some embodiments. The flow rate of the inert carrier gas is about 0 to 90% (e.g., 5 to 80%) of the total gas flow. The plasma is generated in the process chamber or remotely generated and introduced into the process chamber. In one embodiment, an RF frequency of about 100 kHz to 30 MHz is used for plasma generation, and its power ranges from about 50 to 400 W. This step converts the tin oxide into volatile tin hydride and / or volatile organometallic tin compounds, which can be removed from the process chamber, for example, by purging with an inert gas such as He, Ar, or N2.

[0040] Next, in step 205, the carbon-containing polymer is removed by exposing the carbon-containing polymer to a plasma formed in O2. In one example, O2 is introduced into the process chamber either alone or together with an inert carrier gas (e.g., He, Ar, or N2), and the plasma is formed directly in the process chamber or remotely formed and supplied to the process chamber. An RF frequency of about 100 kHz to 30 MHz and a power of about 50 to 400 W are used in this step in some embodiments.

[0041] Next, in step 207, if tin oxide remains in the process chamber, steps 203 and 205 are repeated. In some embodiments, the cleaning method includes performing 4 to 10 cycles, each cycle including one tin oxide removal step 203 and one carbon-containing polymer removal step 207. The temperature and pressure of each of steps 203 and 205 may be the same or different. In one embodiment, the entire cleaning process is performed at a substantially constant temperature in the range of about 30 to 140 °C, for example, 30 to 120 °C, or 80 to 120 °C. The pressure of each of steps 203 and 205 can be about 0.1 to 20 Torr, for example, about 0.5 to 6.0 Torr. The flow rate of the process gas depends on the size of the process chamber and can range, for example, from about 100 to 20,000 sccm.

[0042] The method described herein is used for cleaning tin oxide in a process chamber. In alternative embodiments, the method can be used to etch a tin oxide layer on other substrates such as semiconductor substrates. For example, the processes described with reference to FIGS. 1, 2, and 3A - 3D can be used to etch tin oxide on a semiconductor wafer. For example, in some embodiments, the process begins by providing a semiconductor substrate having a tin oxide layer deposited thereon (e.g., a tin oxide mandrel or a tin oxide spacer). For example, the tin oxide layer may be deposited by CVD or ALD using a reaction between a tin-containing precursor and an oxygen-containing precursor as described herein. Next, the semiconductor substrate is exposed to a process gas containing H2 and a hydrocarbon (the process gas may be activated in a plasma), converting at least a portion of the tin oxide layer into volatile compounds and simultaneously forming a non-volatile carbon-containing polymer. In this step, at least a portion of the tin oxide is removed from the surface of the substrate. Next, the substrate is exposed to an oxygen-containing reactant (e.g., O2 in a plasma) or H2 in the absence of a hydrocarbon to remove the carbon-containing polymer. After removal of the carbon-containing polymer, the steps may be repeated the number of times necessary to etch the desired amount of tin oxide.

[0043] In some embodiments, the method further includes applying a photoresist to a semiconductor substrate, exposing the photoresist, patterning the photoresist to transfer a pattern to the semiconductor substrate, and selectively removing the photoresist from the semiconductor substrate. In some embodiments, the photoresist is applied prior to exposure of tin oxide to hydrogen and hydrocarbons, thereby forming a substrate in which a photoresist layer covers (but does not necessarily contact) a tin oxide layer. In some embodiments, the pattern is transferred from the photoresist to the semiconductor substrate prior to exposure of tin oxide to hydrogen and hydrocarbons. In some embodiments, the step of transferring the pattern to the semiconductor substrate includes exposure of tin oxide to hydrogen and hydrocarbons and etching, as described herein.

[0044] As used herein, the term "semiconductor substrate" refers to a substrate at any stage of semiconductor device fabrication that includes semiconductor material anywhere within its structure. It is understood that it is not necessary to expose the semiconductor material in the semiconductor substrate. A semiconductor wafer having multiple layers of other materials (e.g., dielectrics) covering the semiconductor material is an example of a semiconductor substrate. The disclosed embodiments can be implemented on a semiconductor wafer such as a 200 mm, 300 mm, or 450 mm semiconductor wafer. However, the disclosed embodiments are not so limited. The semiconductor wafer can be of various shapes, sizes, and materials. In addition to semiconductor wafers, other types of workpieces on which the disclosed embodiments can be utilized include various articles such as printed circuit boards.

[0045] Device The provided method can be implemented in various process chambers such as ALD, CVD, and PVD process chambers. For example, the provided method can be implemented in a Striker® ALD apparatus manufactured by Lam Research Corporation of Fremont, California. In one embodiment, an apparatus is provided, the apparatus including a process chamber having an inlet for introducing process gas, and a controller having program instructions for performing any of the method steps described herein. For example, the controller may include program instructions configured to expose a process chamber having a layer of tin oxide to a process gas including H2 and a hydrocarbon to convert the tin oxide to a volatile compound while forming a carbon-containing polymer, and then to cause removal of the carbon-containing polymer by exposing the carbon-containing polymer to an oxygen-containing reactant (e.g., O2 in a plasma) or H2 in the absence of the hydrocarbon. The apparatus may also include a system for generating plasma and a heater for maintaining a desired temperature throughout the cleaning process.

[0046] FIG. 4 schematically shows one embodiment of a process station 400 that can be used to deposit a material (e.g., tin oxide) using atomic layer deposition (ALD) and / or chemical vapor deposition (CVD), either of which may be plasma enhanced. The process station 400 may be used to clean tin oxide deposits using the method provided herein. For simplicity, the process station 400 is illustrated as a stand-alone process station having a process chamber body 402 for maintaining a low-pressure environment. However, it will be recognized that multiple process stations 400 may be included in a common process tool environment. Further, in some embodiments, it will be recognized that one or more hardware parameters of the process station 400 (including those described in detail below) may be programmatically adjusted by one or more computer controllers.

[0047] The process station 400 is in fluid communication with a reactant supply system 401 for supplying process gas to a distribution showerhead 406. The reactant supply system 401 includes a mixing vessel 404 for blending and / or conditioning the process gas supplied to the showerhead 406. One or more mixing vessel inlet valves 420 may control the introduction of process gas into the mixing vessel 404. Similarly, a showerhead inlet valve 405 may control the introduction of process gas into the showerhead 406.

[0048] Some of the reactants used during ALD deposition may be stored in liquid form prior to vaporization and subsequent supply to the process station. For example, the embodiment of FIG. 4 includes a vaporization point 403 for vaporizing a liquid reactant supplied to the mixing vessel 404. In some embodiments, the vaporization point 403 may be a heated vaporizer. Reactant vapor generated from such a vaporizer may condense within the downstream supply piping. Exposure of the condensed reactant to non-compatible gases can result in the formation of small particles. These small particles can clog the piping, interfere with valve operation, and contaminate the substrate. Some approaches to address these issues involve sweeping and / or evacuating the supply piping to remove residual reactants. However, sweeping the supply piping can increase the cycle time of the process station and potentially reduce the throughput of the process station. Accordingly, in some embodiments, the supply piping downstream of the vaporization point 403 may be heat traced. In some examples, the mixing vessel 404 may also be heat traced. In one non-limiting example, the piping downstream of the evaporation point 403 has a temperature ramp profile ranging from about 100°C to about 150°C at the mixing vessel 404.

[0049] In some embodiments, the liquid reactant may be vaporized in a liquid injector. For example, the liquid injector may inject pulses of the liquid reactant into a carrier gas stream upstream of the mixing vessel. In one scenario, the liquid injector may vaporize the reactant by flashing the liquid from high pressure to low pressure. In another scenario, the liquid injector may atomize the liquid into dispersed micro-droplets and subsequently vaporize the micro-droplets in a heated supply tube. It will be appreciated that small droplets may vaporize faster than large droplets, reducing the delay between liquid injection and complete vaporization. The faster the vaporization, the shorter the length of the piping downstream from the vaporization point 403 may be. In one scenario, the liquid injector may be directly attached to the mixing vessel 404. In another scenario, the liquid injector may be directly attached to the showerhead 406.

[0050] In some embodiments, a liquid flow controller may be provided upstream of the vaporization point 403 to control the mass flow rate of the liquid that is vaporized and supplied to the process station 400. For example, the liquid flow controller (LFC) may include a thermal mass flow meter (MFM) located downstream of the LFC. Next, the plunger valve of the LFC may be adjusted in response to a feedback control signal provided by a proportional integral derivative (PID) controller that communicates electrically with the MFM. However, it may take more than one second to stabilize the liquid flow using feedback control. This may increase the metering supply time of the liquid reactant. Thus, in some embodiments, the LFC may be dynamically switched between a feedback control mode and a direct control mode. In some embodiments, the LFC may be dynamically switched from the feedback control mode to the direct control mode by disabling the sensing tubes of the LFC and the PID controller. In some embodiments, the apparatus includes a container for holding a liquid precursor (e.g., an organotin compound) and a conduit that enables the precursor vapor to be carried to the process chamber along with an inert carrier gas (e.g., Ar, He, or N2).

[0051] The showerhead 406 distributes the process gas towards the substrate 412 during deposition. In the embodiment shown in FIG. 4, the substrate 412 is shown positioned under the showerhead 406 and placed on the pedestal 408. It is understood that the substrate is removed from the process chamber during cleaning. The showerhead 406 may have any suitable shape and may have any suitable number and arrangement of ports for distributing the process gas to the substrate 412 or for distributing the process gas during a cleaning operation.

[0052] In some embodiments, a microvolume 407 is located under the showerhead 406. By performing ALD and / or CVD processes in a microvolume rather than the overall volume of the process station, it is possible to shorten the exposure and sweep times to reactants, shorten the time to change process conditions (e.g., pressure, temperature, etc.), limit the exposure of the process station robot to the process gas, and so on. Exemplary microvolume sizes include, but are not limited to, volumes from 0.1 liter to 2 liters. This microvolume also affects the productivity throughput. Since the purge is faster and the precursor partial pressure within the microvolume is higher, the use of the microvolume significantly shortens the cycle time.

[0053] In some embodiments, the pedestal 408 may be raised or lowered to expose the substrate 412 to the microvolume 407 and / or to change the volume of the microvolume 407. For example, during the substrate transfer step, the pedestal 408 may be lowered to allow the substrate 412 to be placed on the pedestal 408. During the deposition process step, the pedestal 408 may be raised to position the substrate 412 within the microvolume 407. In some embodiments, the microvolume 407 may completely surround the substrate 412 and a portion of the pedestal 408 to form a high-flow impedance region during the deposition process.

[0054] Optionally, pedestal 408 may be lowered and / or raised during part of the deposition or cleaning process to adjust process pressure, reactant concentration, etc. within microvolume 407. In one scenario where process chamber body 402 maintains a base pressure during the deposition process, microvolume 407 can be evacuated by lowering pedestal 408. It will be appreciated that in some embodiments, the height of the pedestal may be programmatically adjusted by a suitable computer controller.

[0055] As an exemplary change to the microvolume described herein, reference is made to a height-adjustable pedestal, but it will be appreciated that in some embodiments, the position of showerhead 406 may be adjusted relative to pedestal 408 to vary the volume of microvolume 407. Further, it will be appreciated that the vertical position of pedestal 408 and / or showerhead 406 may be changed by any suitable mechanism within the scope of the present disclosure. In some embodiments, pedestal 408 may include a rotation axis for rotating the orientation of substrate 412. It will be appreciated that in some embodiments, one or more of these exemplary adjustments may be programmatically implemented by one or more suitable computer controllers.

[0056] Returning to the embodiment shown in FIG. 4, the showerhead 406 and pedestal 408 are in electrical communication with an RF power source 414 and a matching network 416 for supplying power to the plasma. In some embodiments, the plasma energy may be controlled by controlling one or more of the process station pressure, gas concentration, RF source power, RF source frequency, and plasma power pulse timing. For example, the RF power source 414 and the matching network 416 may be operated at any suitable power to form a plasma having radical species of a desired composition. Examples of suitable power are included above. Similarly, the RF power source 414 may supply RF power at any suitable frequency. In some embodiments, the RF power source 414 may be configured to independently control a high frequency RF power source and a low frequency RF power source with respect to each other. Exemplary low frequency RF frequencies may include, but are not limited to, frequencies from 50 kHz to 600 kHz. Exemplary high frequency RF frequencies may include, but are not limited to, frequencies from 1.8 MHz to 2.45 GHz. It will be appreciated that any suitable parameters may be adjusted discretely or continuously to provide plasma energy for surface reactions. In one non-limiting example, the plasma power may be pulsed intermittently to reduce ion collisions with the substrate surface as compared to a plasma that is continuously powered.

[0057] In some embodiments, the plasma may be monitored in situ by one or more plasma monitors. In one scenario, the plasma power may be monitored by one or more voltage and current sensors (e.g., VI probes). In another scenario, the plasma density and / or process gas concentration may be measured by one or more optical emission spectrometers (OES). In some embodiments, one or more plasma parameters may be programmatically adjusted based on measurements from such in situ plasma monitors. For example, the OES sensor may be used in a feedback loop to provide program control of the plasma power. It will be appreciated that in some embodiments, other monitors may be used to monitor the plasma and other process characteristics. Such monitors include, but are not limited to, infrared (IR) monitors, acoustic monitors, and pressure transducers.

[0058] In some embodiments, the plasma may be controlled via input / output control (IOC) sequence instructions. In one example, instructions for setting the plasma conditions for a plasma process step may be included in a corresponding plasma activation recipe step of a deposition process recipe. Optionally, the process recipe steps may be arranged in sequence such that all instructions for a deposition process step are executed simultaneously with that process step. In some embodiments, instructions for setting one or more plasma parameters may be included in a recipe step preceding the plasma process step. For example, a first recipe step may include instructions for setting the flow rates of an inert gas and / or a reactant gas, instructions for setting the plasma generator to a power set point, and a time delay instruction for the first recipe step. A subsequent second recipe step may include instructions for enabling the plasma generator and a time delay instruction for the second recipe step. A third recipe step may include instructions for disabling the plasma generator and a time delay instruction for the third recipe step. It will be appreciated that these recipe steps may be further subdivided and / or repeated in any suitable manner within the scope of the present disclosure.

[0059] In some embodiments, the pedestal 408 may be temperature controlled by a heater 410. Further, in some embodiments, the pressure control of the deposition processing station 400 may be performed by a butterfly valve 418. As shown in the embodiment of FIG. 4, the butterfly valve 418 throttles the vacuum provided by a downstream vacuum pump (not shown). However, in some embodiments, the pressure control of the process station 400 may also be adjusted by varying the flow rate of one or more gases introduced into the process station 400.

[0060] FIG. 5 shows a schematic diagram of an embodiment of a multi-station processing tool 500 that includes an inbound load lock 502 and an outbound load lock 504, either or both of which may include a remote plasma source. A robot 506 is configured to move wafers from a cassette loaded through a pod 508 at atmospheric pressure to the inbound load lock 502 through an atmospheric port 510 at atmospheric pressure. The wafer is placed on a pedestal 512 of the inbound load lock 502 by the robot 506, the atmospheric port 510 is closed, and the load lock is pumped down. If the inbound load lock 502 includes a remote plasma source, the wafer may be subjected to remote plasma processing in the load lock before being introduced into the process chamber 514. Further, the wafer may also be heated in the inbound load lock 402, for example, to remove moisture and adsorbed gases. Next, a chamber transfer port 516 to the process chamber 514 is opened, and another robot (not shown) places the wafer into the reactor and places it on a pedestal of the first station shown in the reactor for processing. It will be appreciated that although the embodiment illustrated in FIG. 5 includes load locks, in some embodiments, wafers may be placed directly into the process station.

[0061] The illustrated process chamber 514 includes four process stations numbered from 1 to 4 in the embodiment shown in FIG. 5. Each station has a heated pedestal (shown as 518 for station 1) and a gas line inlet. It will be appreciated that in some embodiments, each process station may have different purposes or multiple purposes. Although the illustrated process chamber 514 includes four stations, it will be understood that a process chamber according to the present disclosure may have any suitable number of stations. For example, in some embodiments, the process chamber may have five or more stations, and in other embodiments, the process chamber may have three or fewer stations.

[0062] FIG. 5 also illustrates one embodiment of a wafer handling system 590 for transferring wafers within the process chamber 514. In some embodiments, the wafer handling system 590 may transfer wafers between various process stations and / or between a process station and a load lock. It will be appreciated that any suitable wafer handling system may be used. Non-limiting examples include a wafer carousel and a wafer handling robot. FIG. 5 further shows one embodiment of a system controller 550 used to control the process conditions and hardware state of the processing tool 500. The system controller 550 may include one or more memory devices 556, one or more mass storage devices 554, and one or more processors 552. The processor 552 may include a CPU or computer, analog and / or digital input / output connections, a stepping motor controller board, and the like.

[0063] In some embodiments, system controller 550 controls all operations of process tool 500. System controller 550 executes system control software 558 stored in mass storage device 554, loaded into memory device 556, and implemented by processor 552. System control software 558 may include instructions for controlling timing, gas mixing, chamber pressure and / or station pressure, chamber temperature and / or station temperature, purge conditions and purge timing, wafer temperature, RF power level, RF frequency, substrate, pedestal, chuck position and / or susceptor position, and other parameters of a particular process implemented by process tool 500. System control software 558 may be configured in any suitable manner. For example, various process tool component subroutines or control objects may be written to control the operation of process tool components necessary to implement various process tool processes according to the disclosed cleaning methods. System control software 558 may be coded in any suitable computer-readable programming language.

[0064] In some embodiments, system control software 558 may include input / output control (IOC) sequence instructions for controlling the various parameters described above. For example, each stage of the cleaning process may include one or more instructions for execution by system controller 550. Instructions for setting process conditions for a cleaning process stage may be included in the corresponding cleaning recipe stage.

[0065] Other computer software and / or programs stored in mass storage device 554 and / or memory device 556 associated with system controller 550 may be used in some embodiments. Examples of programs or sections of programs for this purpose include a substrate positioning program, a process gas control program, a pressure control program, a heater control program, and a plasma control program.

[0066] The substrate positioning program may include program code of a process tool component used to load a substrate onto the pedestal 518 and to control the spacing between the substrate and other parts of the process tool 500.

[0067] The process gas control program may include code for stabilizing the pressure of the process station, for controlling the gas composition and flow rate, and optionally for flowing gas to one or more process stations prior to deposition or cleaning. The process gas control program may include code for controlling the gas composition and flow rate within any of the disclosed ranges. The pressure control program may include code for controlling the pressure of the process station, for example, by adjusting a throttle valve of the exhaust system of the process station, the gas flow to the process station, etc. The pressure control program may include code for maintaining the pressure of the process station within any of the disclosed pressure ranges.

[0068] The heater control program may include code for controlling the current to a heating unit used to heat the substrate. Alternatively, the heater control program may control the supply of a heat transfer gas (such as helium) to the substrate. The heater control program may include instructions for maintaining the temperature of the substrate within any of the disclosed ranges.

[0069] The plasma control program may include code for setting the RF power level and frequency applied to the process electrodes of one or more process stations, using any of the RF power levels disclosed herein, for example. The plasma control program may include code for controlling the duration of each plasma exposure.

[0070] In some embodiments, there may be a user interface associated with the system controller 550. The user interface may include a display screen, a graphical software display of the device and / or process conditions, and user input devices such as a pointing device, a keyboard, a touch screen, a microphone, etc.

[0071] In some embodiments, the parameters adjusted by the system controller 550 may be related to the process conditions. Non-limiting examples include process gas composition and flow rate, temperature, pressure, plasma conditions (such as RF power level, frequency, and exposure time), etc. These parameters may be provided to the user in the form of a recipe and may be input using the user interface.

[0072] Signals for monitoring the process may be provided from various process tool sensors to the analog and / or digital input connections of the system controller 550. Signals for controlling the process may be output at the analog and digital output connections of the process tool 500. Non-limiting examples of process tool sensors that may be monitored include mass flow controllers, pressure sensors (such as pressure gauges), thermocouples, etc. Appropriately programmed feedback and control algorithms may be used with the data from these sensors to maintain the process conditions.

[0073] Any suitable chamber may be used to implement the disclosed embodiments. Exemplary deposition apparatuses include, but are not limited to, apparatuses of the ALTUS® product family, VECTOR® product family, STRIKER® product family, and / or SPEED® product family, each available from Lam Research Corporation of Fremont, California, or any of a variety of other commercially available processing systems. Two or more stations may perform the same function. Similarly, two or more stations may perform different functions. Each station can be designed / configured to perform a particular function / method as desired.

[0074] FIG. 6 is a block diagram showing a processing system suitable for performing a tin oxide film deposition process that can be cleaned according to a particular embodiment. System 600 includes a transfer module 603. The transfer module 603 provides a clean pressurized environment to minimize the risk of contamination when the substrate being processed is moved between various reactor modules. Attached to the transfer module 603 are two multi-station reactors 609 and 610, each capable of performing atomic layer deposition (ALD) and / or chemical vapor deposition (CVD) according to a particular embodiment. Reactors 609 and 610 may include a plurality of stations 611, 613, 615, and 617, which may perform deposition operations continuously or discontinuously and may be cleaned according to the disclosed embodiments. The stations may include a heated pedestal or substrate support, one or more gas inlets or showerheads or dispersion plates.

[0075] One or more single-station modules or multi-station modules 607 capable of performing plasma pre-cleaning or chemical (non-plasma) pre-cleaning may also be mounted on the transfer module 603. The module 607 may, in some cases, be used for various processes for preparing the substrate for, for example, a deposition process. The module 607 may also be designed / configured to perform various other processes such as etching or polishing. The system 600 also includes one or more wafer source modules 601 for storing wafers before and after processing. An atmospheric robot (not shown) in the atmospheric transfer chamber 619 may first take the wafer out of the source module 601 and load it into the load lock 621. A wafer transfer device (generally a robot arm unit) in the transfer module 603 moves the wafer from the load lock 621 to a module attached to the transfer module 603 and also moves the wafer between modules.

[0076] In various embodiments, a system controller 629 is used to control the process conditions during deposition and cleaning. The controller 629 typically includes one or more memory devices and one or more processors. The processor may include a CPU or computer, analog and / or digital input / output connections, a stepping motor controller board, and the like.

[0077] The controller 629 may control all of the operations of the deposition apparatus. The system controller 629 implements system control software including a series of instructions for controlling timing, gas mixing, chamber pressure, chamber temperature, temperature, radio frequency (RF) power level, wafer chuck position or pedestal position, and other parameters of a particular process. Other computer programs stored in a memory device associated with the controller 629 may be used in some embodiments.

[0078] Typically, there is a user interface associated with the controller 629. The user interface may include a display screen, a graphical software display of device and / or process conditions, and user input devices such as a pointing device, keyboard, touch screen, microphone, etc.

[0079] The system control logic may be configured in any suitable manner. Generally, the logic can be designed or configured in hardware and / or software. Instructions for controlling the drive circuit may be hard-coded or provided as software. The instructions may be provided by "programming". Such programming is understood to include any form of logic, such as logic hard-coded in a digital signal processor, an application-specific integrated circuit, and other devices having specific algorithms implemented in hardware. Programming is also understood to include software or firmware instructions that may be implemented on a general-purpose processor. The system control software may be coded in any suitable computer-readable programming language.

[0080] The computer program code for controlling the germanium-containing reducing agent pulse, the hydrogen flow, the tungsten-containing precursor pulse, and other processes in the process sequence can be written in any conventional computer-readable programming language (e.g., assembly language, C, C++, Pascal, Fortran, etc.). The compiled object code or script is executed by the processor to perform the tasks specified within the program. Also, as shown, the program code may be hard-coded.

[0081] The controller parameters are related to process conditions such as, for example, process gas composition and flow rate, temperature, pressure, cooling gas pressure, substrate temperature, and chamber wall temperature. These parameters may be provided to the user in the form of a recipe and may be input using a user interface. Signals for monitoring the process may be provided by the analog and / or digital input connections of the system controller 629. Signals for controlling the process are output at the analog and digital output connections of the deposition apparatus 600.

[0082] The system software may be designed or configured in many different ways. For example, various chamber component subroutines or control objects may be written to control the operation of the chamber components necessary to perform deposition and cleaning processes according to the disclosed embodiments. Examples of programs or sections of programs for this purpose include substrate positioning code, process gas control code, pressure control code, and heater control code.

[0083] In some embodiments, the controller 629 is part of a system, and such a system may be part of the examples described above. Such a system may comprise a semiconductor processing apparatus including one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (such as a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling the operation of the system before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as a “controller” and may control various components or sub-components of the system. The controller 629 may, depending on the processing requirements and / or the type of system, control any of the processes disclosed herein, such as the supply of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings in some systems, RF matching circuit settings, frequency settings, flow rate settings, fluid supply settings, position and motion settings, wafer transfer into and out of tools, and wafer transfer into and out of other transfer tools and / or load locks connected or interfaced with a particular system.

[0084] Broadly, the controller may be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receive commands, issue commands, control operations, enable cleaning operations, enable endpoint measurements, etc. The integrated circuits may include a chip in the form of firmware that stores program instructions, a digital signal processor (DSP), a chip defined as an application specific integrated circuit (ASIC), and / or one or more microprocessors, i.e., a microcontroller that executes program instructions (e.g., software). The program instructions may be conveyed to the controller in the form of various individual settings (or program files) that define operating parameters for performing specific processing on or for a semiconductor wafer, or operating parameters for the system. The operating parameters may, in some embodiments, be part of a recipe defined by a process engineer to implement one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafer dies.

[0085] In some embodiments, the controller may be part of a computer that is integrated with or coupled to the system, or otherwise network-connected to the system, or coupled to such a computer, or a combination thereof. For example, the controller may be within the "cloud," or may be all or part of a fab host computer system. This enables remote access to wafer processing. The computer may enable remote access to the system, monitor the current progress of fabrication operations, consider the history of past fabrication operations, consider trends or performance criteria from multiple fabrication operations, change the parameters of the current process, set the process steps following the current process, or initiate a new process. In some examples, a remote computer (e.g., a server) can provide a process recipe to the system through a network, such network may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and / or settings, and such parameters and / or settings are then communicated from the remote computer to the system. In some examples, the controller receives instructions in the form of data, and such data specifies parameters for each process step to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed and the type of tool configured to be coordinated or controlled by the controller. Thus, as described above, the controller may be distributed, for example, by comprising one or more individual controllers that are network-connected to each other and cooperate towards a common purpose (such as the processes and controls described herein). An example of a distributed controller for such a purpose is one or more integrated circuits on a chamber that are combined to control processing in the chamber and communicate with one or more integrated circuits that are remotely located (at the platform level, or as part of a remote computer, etc.).

[0086] While not limiting, exemplary systems may include a plasma etching chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etching chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etching (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing system that may be associated with or used in the fabrication and / or manufacture of semiconductor wafers.

[0087] As described above, depending on one or more process steps performed by a tool, the controller may communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, the main computer, another controller, or tools used for transporting the wafer container to or from a tool location and / or load port within a semiconductor manufacturing facility.

Example

[0088] A tin oxide removal method was tested using a tin oxide layer deposited on a semiconductor wafer. In a control experiment, the tin oxide was etched using only a mixture of H2 and CH4 in the plasma. The tin oxide was etched at a significant rate only at high temperatures between 160 °C and 200 °C. FIG. 7 is a plot showing that for this etching chemistry, the etching rate depends on the etching temperature. The etching stopped at low temperatures due to the formation of a non-volatile carbon-containing polymer.

[0089] In another experiment, tin oxide was etched according to the embodiments provided herein. The tin oxide was etched by alternately exposing the substrate to a plasma formed in a mixture of (a) H2 and CH4, followed by (b) a plasma formed in O2. Oxygen plasma exposure results in the removal of the carbon-containing polymer, thereby obtaining a significant tin oxide removal rate even at low temperatures. Specifically, it was possible to remove tin oxide at low temperatures of 80 °C and 120 °C. FIG. 8 is a plot showing that, according to the embodiments provided herein, for the described etching method, the etching rate depends on the etching temperature. By using the provided method, it can be seen that tin oxide can be etched without problems at significantly lower temperatures compared to a control chemistry that does not use a carbon-containing polymer removal step.

[0090] The carbon-containing polymer was visually observed on the process chamber showerhead after H2 / CH4 plasma cleaning without using a carbon-containing polymer removal step. When an O2 plasma treatment step was added after the H2 / CH4 plasma cleaning step, no carbon-containing polymer was observed on the showerhead.

[0091] Further embodiments The apparatuses and processes described herein, such as tin oxide etching on a semiconductor substrate using the provided method, may be used in conjunction with lithographic patterning tools or processes, for example, for the fabrication or manufacture of semiconductor devices, displays, LEDs, solar panels, etc. Although not necessarily so, typically, such apparatus and process treatments are utilized or executed together in a common manufacturing facility. Lithographic patterning of a film generally includes some or all of the following steps, each step enabled using a number of tools available: (1) applying a photoresist to a workpiece (i.e., a substrate) using a spin-on tool or a spray-on tool; (2) curing the photoresist using a hot plate or an oven or a UV curing tool; (3) exposing the photoresist with visible light or UV light or eUV light or X-ray light using a tool such as a wafer stepper; (4) developing the resist to selectively remove the resist using a tool such as a wet bench, thereby patterning the resist; (5) transferring the resist pattern to the underlying film or workpiece by using a dry etching tool or a plasma-assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist stripper.

Claims

1. A method for cleaning a process chamber, comprising: (a) providing a process chamber having a tin oxide layer on at least some portions of the process chamber; (b) exposing the tin oxide layer in the process chamber to a process gas comprising a hydrocarbon and hydrogen (H 2 ) to convert at least a portion of the tin oxide layer to a volatile compound, wherein the exposure of the tin oxide layer to the process gas comprising a hydrocarbon and hydrogen (H 2 ) further results in the formation of a non-volatile carbon-containing polymer; (c) removing the carbon-containing polymer by exposing the carbon-containing polymer to an oxygen-containing reactant or H 2 wherein the exposing to H is carried out in the absence of hydrocarbons 2 and the step of exposing to H is carried out in the absence of hydrocarbons A method comprising:

2. The method according to claim 1, wherein the carbon-containing polymer is removed in step (c) by exposing the carbon-containing polymer to the oxygen-containing reactant.

3. The method according to claim 1, wherein the carbon-containing polymer is removed in step (c) by exposing the carbon-containing polymer to an oxygen-containing reactant selected from the group consisting of O 2 O 3 and H 2 O 2 A method removed by exposure to.

4. The method according to claim 1, wherein the oxygen-containing reactant is plasma-activated O 2 is a method.

5. The method according to claim 1, wherein the oxygen-containing reactant is O 3 and the method.

6. The method according to any one of claims 1 to 4, further comprising repeating step (b) and step (c).

7. The method according to any one of claims 1 to 4, further comprising purging the process chamber after step (b).

8. The method according to any one of claims 1 to 4, wherein the process chamber comprises metal parts.

9. The method according to any one of claims 1 to 4, wherein the process chamber comprises aluminum parts.

10. The method according to any one of claims 1 to 4, wherein the process chamber is selected from the group consisting of an ALD chamber, a CVD chamber, and a PVD chamber.

11. The method according to claim 10, wherein the process chamber is a PEALD chamber or a PECVD chamber.

12. The method according to any one of claims 1 to 4, wherein in step (c), the carbon-containing polymer is exposed to a process gas consisting essentially of H 2 or consisting essentially of a mixture of H 2 and an inert gas.

13. The method according to any one of claims 1 to 4, wherein (c) comprises heating the process chamber during removal of the carbon-containing polymer.

14. An apparatus for processing a semiconductor substrate, comprising: (a) a process chamber having an inlet for a process gas; (b) a controller including program instructions for cleaning the process chamber from a tin oxide layer, the program instructions being configured to: (i) Exposure of the tin oxide layer in the process chamber to a process gas containing a hydrocarbon and hydrogen (H 2 ) for converting at least a part of the tin oxide layer into a volatile compound, wherein the exposure of the tin oxide layer to the process gas containing a hydrocarbon and hydrogen (H 2 ) further results in the formation of a non-volatile carbon-containing polymer, and (ii) Removal of the carbon-containing polymer by exposing the carbon-containing polymer to an oxygen-containing reactant or H 2 wherein the exposure to H is carried out in the absence of hydrocarbons, the removal 2 by exposing to H A controller configured to cause; An apparatus comprising:

15. The apparatus according to claim 14, wherein the oxygen-containing reactant is O 2 , O 3 and H 2 O 2 and is selected from the group consisting of, the apparatus.

16. The apparatus according to claim 14, wherein the apparatus comprises a system for generating a plasma, and the program instructions for (ii) are configured to cause plasma activation of the carbon-containing polymer to O 2 exposure, device.

17. The apparatus according to claim 14, wherein the apparatus comprises a heater, and the program instructions for (ii) are configured to cause exposure of the carbon-containing polymer to plasma-activated O 2 in a heated process chamber.

18. The apparatus according to claim 14, wherein the program instructions are further configured to repeat step (i) and step (ii).

19. A method for etching a tin oxide layer on a semiconductor substrate, comprising: (a) providing a semiconductor substrate having an exposed layer of tin oxide; (b) contacting the exposed tin oxide layer in the process chamber with a process gas comprising a hydrocarbon and hydrogen (H 2 ) to convert at least a portion of the tin oxide layer into a volatile compound, wherein the contacting of the tin oxide layer with the process gas comprising a hydrocarbon and hydrogen (H 2 ) further results in the formation of a non-volatile carbon-containing polymer; (c) removing the carbon-containing polymer by exposing the carbon-containing polymer to an oxygen-containing reactant or H 2 wherein the exposing to H is carried out in the absence of hydrocarbons 2 and the exposing to H is a step carried out in the absence of hydrocarbons A method comprising:

20. The method according to claim 19, wherein before the step (b), a step of applying a photoresist to the semiconductor substrate; a step of exposing the photoresist; a step of patterning the photoresist and transferring the pattern to the semiconductor substrate, wherein the step of transferring the pattern to the semiconductor substrate is performed before the step (b), or the step of transferring the pattern to the semiconductor substrate includes, in the step (b), etching the tin oxide layer by exposing the semiconductor substrate to the process gas containing the hydrocarbon and hydrogen; a step of selectively removing the photoresist from the semiconductor substrate; The method further comprising.

21. The method according to claim 19, wherein before the step (a), SnF 2 , SnCl 4 , SnBr 4 , SnH 4 , tetraethyltin (SnEt 4 ), tetramethyltin (SnMe 4 ), tetrakis(dimethylamino)tin (Sn(NMe 2 )) 4 ), tetrakis(diethylamino)tin (Sn(NEt 2 )) 4 ), tetrakis(ethylmethylamino)tin (Sn(NMeEt) 4 ), (dimethylamino)trimethyltin(IV) (Me 3 Sn(NMe 2 ))), dibutyltin diacetate (Bu 2 Sn(OAc) 2 ), Sn(II)(1,3-bis(1,1-dimethylethyl)-4,5-dimethyl-(4R,5R)-1,3,2-diazastannolidine-2-ylidene), N 2 , N 3 -di-tert-butyl-butane-2,3-diamino-stann(II), bis[bis(trimethylsilyl)amino]tin(II) 【Chemical Formula 1A】 (wherein TMS is trimethylsilyl), dibutyldiphenyltin ​ hexaphenylditin (IV) [Chemical Formula 3A] tetraallyltin 【Chemical Formula 4A】 tetravinyltin 【Chemical Formula 5A】 tin(II) acetylacetonate 【Chemical Formula 6A】 tricyclohexyltin hydride 【Chemical Formula 7A】 trimethyl(phenylethynyl)tin 【Chemical Formula 8A】 trimethylphenyltin 【Chemical Formula 9A】 trimethyltin chloride 【Chemical Formula 10A】 dimethyltin dichloride 【Chemical 11A】 and methyltin trichloride 【Chemical Formula 12A】 The method further comprising depositing the tin oxide layer using a tin-containing precursor selected from the group consisting of.

22. The method according to claim 19, wherein prior to said step (a), using a tin-containing precursor selected from the group consisting of tin tetramethyl (SnMe 4 ), tin tetraethyl (SnEt 4 ), tetrakis(dimethylamino)tin, and (dimethylamino)trimethyltin(IV), further comprising depositing the layer of tin oxide.

23. An apparatus for processing a semiconductor substrate, the apparatus comprising (a) a process chamber having an inlet for a process gas and a substrate support for holding the semiconductor substrate in place; (b) a controller including program instructions for etching tin oxide on the semiconductor substrate, the program instructions being (i) To convert at least a part of the tin oxide layer into a volatile compound, contacting the tin oxide layer on the semiconductor substrate with a process gas containing a hydrocarbon and hydrogen (H 2 ), wherein the exposure of the tin oxide layer to the process gas containing a hydrocarbon and hydrogen (H 2 ) further results in the formation of a non-volatile carbon-containing polymer, the contacting, and (ii) removal of the carbon-containing polymer by exposing the carbon-containing polymer to an oxygen-containing reactant or H 2 wherein the exposure to H is carried out in the absence of hydrocarbons, 2 removal configured to cause; The apparatus comprising.

24. The method according to claim 1, wherein the tin oxide layer contains at least 90% by weight of tin oxide (SnO2).

25. The method according to claim 19, wherein the tin oxide layer contains at least 90% by weight of tin oxide (SnO2).

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