WO2025250609A1

WO2025250609A1 - Coating surfaces within a pumping path of a processing tool

Info

Publication number: WO2025250609A1
Application number: PCT/US2025/031156
Authority: WO
Inventors: Gordon Alex MACDONALD; Kurt Augustus SPIES; Vineet MALIEKKAL; Ragesh PUTHENKOVILAKAM; Kapu Sirish Reddy; Christopher Nicholas IADANZA
Original assignee: Lam Research Corp
Current assignee: Lam Research Corp
Priority date: 2024-05-30
Filing date: 2025-05-28
Publication date: 2025-12-04
Anticipated expiration: 2026-11-30

Abstract

Systems and methods are disclosed for applying a coating to surfaces within a pumping path of an exhaust system of a processing tool. In one example, a method comprises introducing a coating precursor mixture into the pumping path and introducing a reactant gas mixture into a remote plasma generator fluidically coupled to the exhaust system. Radical species of the reactant gas mixture are generated at the remote plasma generator. The radical species of the reactant gas mixture are flowed into the pumping path. The coating precursor and the reactive species of the reactant gas mixture are reacted within the pumping path to form the coating on the surfaces.

Description

COATING SURFACES WITHIN A PUMPING PATH OF A PROCESSING

TOOL

BACKGROUND

[0001] Electronic device fabrication processes can involve many steps of material deposition, patterning, and removal to form integrated circuits on substrates. Various methods can be used to deposit films of materials onto a substrate. As one example, chemical vapor deposition (CVD) can be used to deposit a film by exposing a substrate to a flow of gas phase precursors. The gas phase precursors undergo chemical reactions to form a film on the substrate. Plasma-enhanced CVD (PECVD) utilizes a plasma to provide energy for the chemical conversion of the precursors to the film. PECVD processes can be used to deposit a wide variety of films, including carbon films.

SUMMARY

[0002] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.

[0003] Systems and methods are disclosed for applying a coating to surfaces within a pumping path of an exhaust system of a processing tool. In one example, a method comprises introducing a coating precursor mixture into the pumping path and introducing a reactant gas mixture into a remote plasma generator fluidically coupled to the exhaust system. Radical species of the reactant gas mixture are generated at the remote plasma generator. The radical species of the reactant gas are flowed into the pumping path. The coating precursor and the reactive species of the reactant gas are reacted within the pumping path to form the coating on the surfaces.

[0004] In some such examples, introducing the coating precursor mixture into the pumping path additionally or alternatively comprises introducing the coating precursor mixture through a gas inlet of a processing chamber of the processing tool, the processing chamber fluidically coupled to the pumping path. [0005] In some such examples, introducing the coating precursor mixture into the pumping path additionally or alternatively comprises introducing the coating precursor mixture via the exhaust system upstream of a pump of the pumping path and downstream of a processing chamber of the processing tool.

[0006] In some such examples, the coating precursor mixture additionally or alternatively comprises a silicon-containing precursor.

[0007] In some such examples, the coating is additionally or alternatively a silicon oxide coating.

[0008] In some such examples, the reactant gas mixture additionally or alternatively comprises an oxygen-containing gas.

[0009] In some such examples, the reactant gas mixture additionally or alternatively comprises a nitrogen-containing gas.

[0010] In some such examples, the method additionally or alternatively comprises removing a prior coating before forming the coating.

[0011] In some such examples, removing the prior coating additionally or alternatively comprises flowing a fluorine containing plasma generated in the remote plasma generator to the pumping path to remove the prior coating.

[0012] In some such examples, the method additionally or alternatively comprises monitoring the pumping path for one or more fluorinated compounds of the coating; and ceasing flowing the fluorine containing plasma responsive to a concentration of the one or more fluorinated compounds of the coating in the pumping path decreasing below a threshold concentration.

[0013] In another example, a processing tool is presented. The processing tool comprises a processing chamber having one or more gas inlets; an exhaust system fluidically coupled to the processing chamber, the exhaust system comprising at least a throttle valve and a pump situated in a pumping path; and a remote plasma generator fluidically coupled to the exhaust system. A storage machine holding instructions executable by the logic machine to introduce a coating precursor mixture into the processing chamber via the one or more gas inlets; introduce a reactant gas mixture into a remote plasma generator fluidically coupled to the exhaust system; generate radical species of the reactant gas mixture at the remote plasma generator; flow the radical species of the reactant gas into the pumping path; and react the coating precursor mixture and the reactive species of the reactant gas within the pumping path to form the coating on the surfaces. [0014] In some such examples, the coating precursor mixture additionally or alternatively comprises a silicon-containing precursor.

[0015] In some such examples, the coating is additionally or alternatively a silicon oxide coating.

[0016] In some such examples, the reactant gas mixture additionally or alternatively comprises an oxygen-containing gas.

[0017] In some such examples, the reactant gas mixture additionally or alternatively comprises a nitrogen-containing gas.

[0018] In some such examples, the storage machine additionally or alternatively holds instructions executable by the logic machine to flow a fluorine-containing plasma generated in the remote plasma generator to the pumping path to remove a prior coating. [0019] In some such examples, the processing tool additionally or alternatively comprises an infrared spectrometer positioned within the pumping path, and the storage machine additionally or alternatively holds instructions executable by the logic machine to cease flowing the fluorine containing plasma responsive to a concentration of one or more fluorinated compounds of the coating in the exhaust pathway decreasing below a threshold concentration.

[0020] In another example, a method of applying a coating to surfaces within a pumping path of an exhaust system of a processing tool is presented. The method comprises introducing a first coating precursor mixture into the pumping path; introducing a reactant gas mixture into a remote plasma generator fluidically coupled to the exhaust system; generating radical species of the reactant gas mixture at the remote plasma generator; flowing the radical species of the reactant gas into the pumping path; and reacting the first coating precursor mixture and the reactive species of the reactant gas within the pumping path to form a first coating on the surfaces. A fluorine-containing plasma generated in the remote plasma generator is flowed to the pumping path to remove the first coating. The exhaust pathway is monitored for one or more fluorinated compounds of the first coating. The method further comprises ceasing flowing the fluorine containing plasma responsive to a concentration of the one or more fluorinated compounds of the first coating in the exhaust pathway decreasing below a threshold concentration; and applying a second coating to surfaces within the pumping path of the exhaust system of the processing tool.

[0021] In some such examples, applying a second coating to surfaces within the pumping path of the exhaust system of the processing tool additionally or alternatively comprises introducing a second coating precursor mixture into the pumping path; introducing the reactant gas mixture into the remote plasma generator; generating radical species of the reactant gas mixture at the remote plasma generator; flowing the radical species of the reactant gas into the pumping path; and reacting the second coating precursor mixture and the reactive species of the reactant gas within the pumping path to form the second coating on the surfaces.

[0022] In some such examples, the first coating is additionally or alternatively different from the second coating.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 shows a block diagram of an example processing tool.

[0024] FIG. 2 shows a flow diagram for an example method of applying a coating to surfaces within a pumping path of an exhaust system of a processing tool.

[0025] FIG. 3 schematically shows the application of a coating to surfaces within a pumping path of an exhaust system of a processing tool.

[0026] FIG. 4 shows a flow diagram for an example method of removing and re-applying a coating to surfaces within a pumping path of an exhaust system of a processing tool.

[0027] FIG. 5 schematically shows the removal of a coating from surfaces within a pumping path of an exhaust system of a processing tool.

[0028] FIG. 6 schematically shows an example computing system.

DETAILED DESCRIPTION

[0029] The term “coating” generally represents a film deposited onto a surface. The term “coating precursor mixture” generally represents a mixture of gases that can be used to deposit a coating on a surface.

[0030] The term “fluorinated compounds” generally represents a chemical comprising one or more fluorine atoms. Example fluorinated compounds include hydrogen fluoride (HF), fluorine (F2), xenon difluoride (XeF2), and nitrogen trifluoride (NF3). The term “fluorine-containing plasma” generally represents a plasma generated from one or more fluorinated compounds.

[0031] The term “gas inlet” generally represents a conduit for providing one or more gases to processing chamber of a processing tool. [0032] The term “inert gas” generally represents a gas that is non-reactive in a processing environment. Example inert gases include helium, neon, argon, krypton, xenon, radon, and molecular nitrogen in some processing environments (e.g. nonplasma environments).

[0033] The term “nitrogen-containing gas” generally represents a gas species containing one or more nitrogen atoms. Example nitrogen-containing gases include molecular nitrogen (N2), ammonia (NH3), and nitrous oxide (N2O).

[0034] The term “oxygen-containing gas” generally represents a gas species containing one or more oxygen atoms. Examples of oxygen-containing gases comprise molecular oxygen (O2), water vapor (H2O) and ozone (O3).

[0035] The term “plasma” generally represents a gas comprising cations and free electrons. A plasma may be used to generate reactive chemical species from a precursor molecule introduced into the plasma. The term “in-situ plasma” may generally represent a plasma to which a substrate is directly exposed during a process. The term “remote plasma” may generally represent a plasma that is located remote from a substrate being processed. The term “capacitively coupled plasma” generally represents a plasma generated between two electrodes. The term “inductively coupled plasma” generally represents a plasma generated by electric currents which are produced by electromagnetic induction.

[0036] The term “plasma generator” generally represents a device configured to generate a plasma to provide reactive species and/or energetic ions for substrate processing in a processing chamber.

[0037] The term “processing chamber” generally represents an enclosure in which chemical and/or physical processes are performed on substrates. The pressure, temperature and atmospheric composition within a processing chamber are controllable to perform chemical and/or physical processes.

[0038] The term “processing tool” generally represents a machine including a processing chamber and other hardware configured to enable processing to be carried out in the processing chamber.

[0039] The term “pumping path” generally represents an exhaust pathway for a processing tool that is driven by one or more pumps. The term “exhaust system” generally represents a component of a processing tool used to remove gases and plasmas from a processing chamber. The term “throttle valve” generally represents a mechanical device that functions to regulate downstream pressure within an exhaust system.

[0040] The term “radical species” generally represents a chemical species that includes an unpaired electron. The term “hydrogen radicals” generally represents a hydrogen atom that includes an unpaired electron. The term “oxygen-containing radicals” generally represents a compound that includes one or more oxygen atoms and that includes an unpaired electron.

[0041] The term “silicon-containing precursor” generally represents any material that can be introduced into a processing chamber in a gas phase to form a silicon-containing film on the substrate. Example silicon-containing precursors for forming silicon-containing films using PEALD can comprise materials having the general structure:

[0042] where Rl, R2 and R3 can be the same or different substituents. In various examples, Rl, R2, and R3 can include silanes, siloxy groups, amines, halides, hydrogen, or organic groups such as alkylamines, alkoxy, alkyl, alkenyl, alkynyl, and cyclic groups (such as aromatic groups).

[0043] In some examples, the silicon-containing precursor is an alkoxysilane. Alkoxy silanes that can be used include compounds having a general formula of Hx-Si- (OR)y, where x = 1-3, x+y = 4 and each R is a substituted or unsubstituted aliphatic or aromatic group; and Hx(RO)y,-Si-Si-(OR)yHx, where each R is a substituted or unsubstituted aliphatic or aromatic group. Example alkoxysilanes include tetramethoxysilane (TMOS), diethoxymethylsilane (DEMS), diethoxysilane (DES), dimethoxymethylsilane, dimethoxysilane (DMOS), methyl-diethoxysilane (MDES), methyl-dimethoxysilane (MDMS), t-butoxydisilane, triethoxysilane (TES), and trimethoxysilane (TMS or TriMOS).

[0044] In some examples, the silicon-containing precursor is a siloxane. Siloxanes include materials having Si-O-Si linkages. Example siloxanes include octamethylcyclotetrasiloxane (OMCTS), octamethoxydodecasiloxane (OMODDS), and tetramethylcyclotetrasiloxane (TMCTS). [0045] In some examples, the silicon-containing precursor is an aminosilane. Aminosilanes include materials having a general formula Hx-Si-(NR)y, where x = 1-3, x+y = 4, and R is a substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aromatic group, or hydride group. Example aminosilanes include bisdiethylaminosilane, diisopropylaminosilane, bis(t-butylamino) silane (BTBAS), di-sec-butylaminosilane, and tris(dimethylamino)silane (3DMAS).

[0046] In some examples, the silicon-containing precursor is a halogencontaining silane. In some examples, a halogen-containing silane can comprise at least one hydrogen atom. Such a silane can have a general formula of SiXaHy where y > 1. Example halosilanes include dichlorosilane (H2SiC12), hexachlorodisilane (Si2C16), and diiodosilane (H2SiI2).

[0047] More specific examples of silicon-containing precursors include polysilanes ((SinH2n+2, where n >1, such as silane, disilane, trisilane, and tetrasilane), trisilylamine, tetraethyl orthosilicate (TEOS), methylsilane, trimethylsilane (3MS), ethylsilane, butasilanes, pentasilanes, octasilanes, heptasilane, hexasilane, cyclobutasilane, cycloheptasilane, cyclohexasilane, cyclooctasilane, cyclopentasilane, l,4-dioxa-2,3,5,6-tetrasilacyclohexane, triethoxysiloxane (TRIES), and tetraoxymethylcyclotetrasiloxane (TOMCTS).

[0048] Plasma-enhanced chemical vapor deposition (PECVD) utilizes a plasma to generate reactive species from film precursors that are introduced into the plasma. When film precursor molecules are introduced into the plasma, the energetic ions in the plasma form reactive species from the film precursor molecules. The reactive species then can deposit as a film on a substrate.

[0049] In some PECVD processes, the plasma can be an in-situ plasma formed in a processing chamber of a PECVD tool (e.g. between showerhead and substrate holder electrodes). Other PECVD processes can use a remote plasma to generate reactive species for film deposition, as opposed to an in-situ plasma. A remote plasma is a plasma that is formed at a location remote from, but fluidically connected with, a location in a processing chamber at which a substrate is being processed. Radicals from the remote plasma diffuse to the substrate to deposit at as a film.

[0050] In some PECVD processes, radical polymerization of undeposited precursor can occur within a pumping path of the exhaust system of a PECVD tool. The undeposited precursor can take the form of activated precursor radicals, and/or unactivated precursor molecules. As a more specific example, in a carbon PECVD tool, acetylene (C2H2) can be used as a carbon film precursor. To deposit a carbon film, the acetylene can be activated in a plasma to form carbon-containing radical species such as .C2H, as well as hydrogen radicals (*H). The carbon-containing radicals can react to form a carbon film (for example, amorphous carbon) on a substrate. However, not all carbon-containing radicals that are generated deposit on the substrate. Further, not all acetylene precursor is activated in the plasma. The hydrogen radicals and undeposited carbon-containing radicals can initiate radical polymerization of undeposited acetylene precursor in the exhaust stream from the processing chamber. As a result, polymer materials formed by the radical polymerization can form deposits within the pumping path. Such deposits can be difficult to remove. Material accumulation within the pumping path can eventually lead to process breakdowns from either loss of foreline conductance and/or throttle valve failure.

[0051] Further, the cleaning of the exhaust system results in PECVD tool downtime, and thereby can increase operational costs. Current methods of avoiding such deposits of polymer materials include restricting a process window for the deposition process in a manner determined to result in lesser amounts of deposits. However, this may limit flexibility in process design. While many of the disclosed examples are described using acetylene as a carbon-containing precursor, other suitable carbon-containing precursors can be used in other examples.

[0052] As one possible solution, radical species can be introduced into the pumping path by a remote plasma cleaning system to remove deposited polymer in the pumping path. Where carbon-based polymers are deposited in a pumping path of a carbon film deposition tool, hydrogen radicals or oxygen-containing radicals can be generated by a remote plasma generator and introduced into the pumping path. Hydrogen radicals can react with polymer deposits to form volatile hydrocarbons, thereby helping to remove the polymer deposits. Likewise, oxygen-containing radicals can react with polymer deposits to form volatile carbon oxides (e.g. carbon dioxide and/or carbon monoxide) and water, thereby helping to remove the polymer deposits.

[0053] However, components along a pumping path of a PECVD tool can be made from materials that lead to relatively high radical recombination rates. Components are often made of metals, such as stainless steel or aluminum. Metal surfaces can have higher recombination coefficients than dielectric materials. As a more specific example, an oxygen radical recombination coefficient of stainless steel at 20° C is 3.60 x 10'², whereas the oxygen radical recombination coefficient of silica at 20° C is 1.80 x 10'⁴. Deposition build-up can be mitigated by direct injection of remote plasma cleaning gas into the pumping path either following the deposition process or simultaneous with an upstream deposition. However, direct injection of remote plasma cleaning gas can lead to accelerated degradation of parts that make up the pumping path. Further, certain chemistries (e.g., oxygen radicals) are extremely sensitive to surface chemistry. As such, direct injection of remote plasma gas may be highly inefficient on many of the materials used to make the pumping path (e.g., Aluminum, stainless steel) where surface recombination can be orders of magnitude higher than on dielectric coated surfaces.

[0054] To avoid high radical recombination rates along the pumping path that impact a radical-based cleaning process, metal surfaces within the pumping path can include a coating of a dielectric substance with a lower recombination coefficient than the metal surfaces. Such a coating can be applied to a surface of a component that is within the pumping path prior to assembly of a PECVD tool, thereby lowering recombination rates at the coated surfaces. However, over time, the coating can wear down, again exposing the metal surface and leading to higher radical recombination rates and less effective cleaning. Eroded coatings cannot be easily replenished. Further, any given coating is not equally chemically resistant to all chemistry combinations, thus limiting the deposition or etching process, as well as any direct injection cleaning process, to chemistries that are compatible with the coating.

[0055] Silica undercoating deposition within the processing chamber is a standard process that is known to reduce oxygen and hydrogen radical recombination in the process chamber of the processing tool. However, the standard silica undercoating is deposited by capacitively coupled plasma generated in the processing chamber. As such, the coating remains largely confined to the surfaces of the processing chamber and does not extend into the pumping path. Radicals within the exhaust can still recombine with metallic surfaces in the pumping path.

[0056] Accordingly, examples are disclosed that relate to depositing a coating on surfaces within a pumping path of a PECVD tool to cover a surface having a higher recombination coefficient with a coating having a lower recombination coefficient. The coating can be applied using the ordinary gas flow and plasma capabilities of the PECVD tool, without breaking vacuum. Further, the coating can be cleaned and reapplied as needed, again using the ordinary gas flow and plasma capabilities of the PECVD tool. This can help to maintain the pumping path cleaning capabilities of the PECVD tool, without having to disassemble the PECVD tool to replace a component with a worn coating. In addition to providing for lower recombination rates (and therefore longer radical lifetimes), applying a coating to surfaces of a pumping path as disclosed also can protect the components in the pumping path from degradation by the radicals used to remove the polymer deposits. The lower recombination rates provided by the coating also reduce the non-desired heating caused by radical polymerization on the surfaces of the pumping path. Such non-productive heating can have negative effects such as accelerated deterioration/corrosion of parts and safety concerns due to local heating. The applied coating can be stripped and reapplied, either to replenish eroded coating or to allow for a change in process chemistries within the same processing tool.

[0057] FIG. 1 shows a schematic depiction of an example processing tool 100 configured to perform PECVD. For example, processing tool 100 may be configured for the deposition of carbon films. The processing tool 100 comprises a processing chamber 102 and a substrate holder 104 within the processing chamber. The substrate holder 104 is configured to support a substrate 106 disposed within processing chamber 102. The substrate holder 104 comprises a substrate heater 108. In other examples, a heater can be omitted, or can be located elsewhere within processing chamber 102. The processing tool 100 further comprises a showerhead 110 for introducing processing chemicals into the processing chamber. In some examples, the processing tool 100 comprises a heater configured to heat showerhead 110. The processing tool 100 further comprises an optional secondary purge gas outlet 111. Secondary purge gas outlet 111 is configured to form secondary purge gas flow around the outside edge of showerhead 110.

[0058] The processing tool 100 further comprises flow control hardware 112. The flow control hardware 112 connects processing chemical source(s) to the processing chamber. In the depicted example, the flow control hardware 112 connects a film precursor source 116, an etchant source 118, an inert gas source 122, and a coating precursor source 124, to the processing chamber. The flow control hardware 112 can include any suitable components. For example, the flow control hardware 112 can comprise one or more valves controllable to place a selected gas source or selected gas sources in fluid connection with showerhead 110. The flow control hardware 112 also can comprise one or more mass flow controllers or other controllers for controlling a mass flow rate of gas.

[0059] The film precursor source 116 comprises any suitable precursor compound for forming a film on substrate 106. In some examples, film precursor source 116 is a carbon-containing precursor source. Such a carbon-containing precursor source comprises any suitable precursor compound(s) for forming a carbon film. Examples of carbon-containing precursors include alkanes having a general formula CnH2n+2 where n is an integer in a range of 1 to 10 (such as methane, ethane, etc.), alkenes having a general formula CnEkn where n = 2 to 10 (such asl ethylene, propylene, etc.), and alkynes having a general formula CnH2n-2 where n = 2 to 10 (such as acetylene, propyne, etc.), that are gas-phase under processing conditions. Other examples of carbon- containing film precursors comprise cyclic aliphatic hydrocarbons, aromatic hydrocarbons, heterocyclic compounds, and alkyl amines.

[0060] In some examples, an etchant source 118 is included to introduce an etchant into a precursor gas mix for depositing a carbon film. Etchants can facilitate carbon film deposition. Example etchants can include one or more of hydrogen (H2), ammonia (NEE), hydrazine (N2H2), chlorine (Ch), fluorine (F2), bromine (Bn), iodine (I2), hydrofluoric acid (HF), hydrochloric acid (HC1), hydrobromic acid (HBr), hydroiodic acid (HI), nitrogen trifluoride (NF3), boron trifluoride (BF3), sulfur hexafluoride (SFe), a halocarbon gas having a general formula CaXb (where X comprises one or more of fluorine, chlorine, bromine, or iodine and where a = 1-10), a halohydrocarbon gas having a general formula CaHbXc (where X comprises one or more of fluorine, chlorine, bromine, or iodine and where a = 1-10), carbon monoxide (CO), carbon dioxide (CO2), carbon oxysulfide (COS), sulfur dioxide (SO2), or molecular oxygen (O2).

[0061] The inert gas source 122 comprises any suitable inert gas. Examples include argon, helium, neon, krypton, and xenon, as well as nitrogen in some processing environments.

[0062] The processing tool 100 further comprises an exhaust system 132. The exhaust system 132 is configured to exhaust gases from the processing chamber 102. The exhaust system 132 can comprise any suitable hardware, including one or more low vacuum pumps, one or more high vacuum pumps, and one or more valves for controlling an exhaust flow, such as a throttle valve 133. Together, flow control hardware 112 and exhaust system 132 can be operated to achieve a selected pressure in processing chamber 102 during substrate processing. Example pressures include pressures of 1 Torr to 50 Torr. In more specific examples, the pressure in the processing chamber can be within a range of 1-20 Torr. In other examples, the pressure in the processing chamber can be within a range of 1-10 Torr, within a range of 10-20 Torr, within a range of 20-30 Torr, within a range of 30-40 Torr, or within a range of 40-50 Torr. Further, exhaust system 132 can be operated to purge processing chamber 102. [0063] The processing tool 100 further comprises an RF power source 134 configured to form a RF plasma in processing chamber 102 using a gas mixture. The RF power source 134 can supply RF power to the showerhead electrode or substrate holder electrode in various examples. As shown in FIG. 1, the RF power is provided to substrate holder 104, and showerhead 110 is configured as a grounded opposing electrode. In other examples, the RF power source 134 can supply RF power to showerhead 610, and substrate holder 604 can be grounded. In the depicted example, a capacitively coupled plasma can be formed in processing chamber 102 between showerhead 110 and substrate holder 104. In other examples, an inductively coupled plasma can be used. The processing tool 100 further includes a matching network 136 for impedance matching of the RF power source 134.

[0064] In some examples, the radiofrequency power source 134 is configured to provide RF power comprising a lower-frequency (LF) RF power 134A and a higher- frequency (HF) RF power 134B to form a multi-frequency plasma. Example frequencies for the lower-frequency RF power include frequencies of 40 kHz to 3 MHz. Examples frequencies for the higher-frequency RF power include frequencies of 3 MHz to 300 MHz. In other examples, the radiofrequency power source 134 is configured to supply a single frequency (e.g. HF) of RF power.

[0065] The processing tool 100 further comprises a controller 150 configured to control operation of the processing tool. The controller 150 is operatively coupled to the substrate heater 108, the flow control hardware 112, the exhaust system 132, and the RF power source 134, among other processing tool components. The controller 150 is configured to control various functions of processing tool 100 to perform PECVD.

[0066] The processing tool 100 further comprises a remote plasma generator 160. The remote plasma generator 160 is configured to introduce radical species into a vacuum line 161 upstream of the throttle valve 133. The remote plasma generator 160 can be used to generate radicals to clean polymer deposits within the pumping path downstream of the location at which the radicals are introduced into the vacuum line 161. The remote plasma generator 160 can receive a reactant gas from reactant gas source 170. For example, an oxygen-containing gas from an oxygen-containing gas source can be used to generate oxygen-containing radicals, which can oxidize polymer deposits. Any suitable oxygen-containing gas can be used. Examples include molecular oxygen (O2), water vapor (H2O), ozone (O3), hydrogen peroxide (H2O2), nitrogen oxides (e.g. nitrous oxide (N2O)), and carbon dioxide (CO2). Reactant gas may be supplied as a reactant gas mixture with an inert gas from inert gas source 172.

[0067] Also, the remote plasma generator 160 can be used to generate radicals to form a coating on surfaces within the pumping path, including surfaces with vacuum line 161 and exhaust system 132 (such as surfaces of throttle valve 133) such as conduit 164. For example, oxygen-containing radicals can be used to form an oxide coating on surfaces within the pumping path. As one example, processing tool 100 can be configured to form a silicon oxide coating within the pumping path. In FIG. 1, coating precursor source 124 may be a silicon-containing precursor source used to provide a silicon-containing precursor to showerhead 110. In some examples, flow control hardware 112 can be configured to introduce coating precursor into the pumping path downstream of the processing chamber 102 and upstream of the throttle valve 133, as indicated at 166.

[0068] Any suitable silicon-containing precursor that is capable of reacting with oxygen-containing radicals can be introduced into a pumping path of a CVD tool to coat surfaces within the pumping path with a silicon oxide coating. Some examples of silicon-containing precursors may include materials having the general structure: where Ri, R2 and R3 can be the same or different substituents. In various examples, Ri, R2, and R3 can include silanes, amines, halides, hydrogen, or organic groups such as alkylamines, alkyl, alkenyl, alkynyl, and cyclic groups (such as aromatic groups).

[0069] Other examples of silicon-containing precursors include alkoxysilanes. Alkoxysilanes that can be used include compounds having a general formula of H_x-Si- (OR)_y, where x = 0 to 3, x + y = 4 and each R is a substituted or unsubstituted aliphatic or aromatic group; and H_x(RO)y-Si-Si-(OR)yH_x, where each R is a substituted or unsubstituted aliphatic or aromatic group. Example alkoxysilanes include tetramethoxysilane (TMOS), tetraethylorthosilicate (TEOS), diethoxymethylsilane (DEMS), di ethoxy silane (DES), dimethoxymethylsilane, dimethoxysilane (DMOS), methyl-diethoxysilane (MDES), methyl-dimethoxysilane (MDMS), t-butoxydisilane, triethoxysilane (TES), and trimethoxysilane (TMS or TriMOS).

[0070] Further examples of silicon-containing precursors include siloxanes. Siloxanes include materials having Si-O-Si linkages. Example siloxanes include octamethylcyclotetrasiloxane (OMCTS), octamethoxydodecasiloxane (OMODDS), and tetramethylcyclotetrasiloxane (TMCTS).

[0071] Additional examples of silicon-containing precursors include aminosilanes. Aminosilanes include materials having a general formula H_x-Si-(NR)_y, where x = 1-3, x + y = 4, and R is a substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aromatic group, or hydride group. Example aminosilanes include bisdiethylaminosilane, diisopropylaminosilane, bis(t-butylamino) silane (BTBAS), di- sec-butylaminosilane, and tris(dimethylamino)silane (3DMAS).

[0072] Further examples of silicon-containing precursors include halogencontaining silanes. A halogen-containing silane can be referred to as a halosilane. In some examples, a halosilane can comprise at least one hydrogen atom. Such a silane can have a general formula of SiXaHy where y > 1. Example halosilanes include dichlorosilane (EhSiCh), hexachlorodisilane (Si2Cle), and diiodosilane (H2SH2).

[0073] Yet further examples of silicon-containing precursors include silane (SiEU) and polysilanes ((Si_nH2n+2, where n >1, such as disilane, trisilane, and tetrasilane), trisilylamine, methylsilane, trimethylsilane (3MS), ethylsilane, butasilanes, pentasilanes, octasilanes, heptasilanes, hexasilanes, cyclobutasilane, cycloheptasilane, cyclohexasilane, cyclooctasilane, cyclopentasilane, 1, 4-dioxa-2, 3,5,6- tetrasilacyclohexane, triethoxysiloxane (TRIES), and tetraoxymethylcyclotetrasiloxane (TOMCTS).

[0074] Remote plasma generator 160 may further be supplied with a fluorine- containing gas from a fluorine containing gas source 174. The remote plasma generator 160 can generate reactive fluorine-containing species to etch or otherwise clean the pumping path before applying or re-applying a coating. Example fluorine-containing gases include molecular fluorine (F2), hydrogen fluoride (HF), various fluorocarbons (e.g. CxF_y), hydrofluorocarbons (e.g. C_xH_yF_x), nitrogen trifluoride (NF3), and sulfur fluorides (e.g. sulfur hexafluoride (SFe)).

[0075] One solution to radical recombination in the pumping path of a processing tool is to introduce an undercoat within the pumping path by utilizing a direct injection cleaning apparatus (e.g., remote plasma generator). Using existing foreline hardware, a silica undercoat can be deposited on the throttle valve plate and into the foreline of the pumping path and dramatically reduce the oxygen radical recombination rate. This process can improve the clean efficiency of the PV plate and should allow for improved clean times and cleaner hardware.

[0076] FIG. 2 shows a flow diagram for an example method 200 for applying a coating to surfaces within a pumping path of an exhaust system of a processing tool. Method 200 may be carried out by a controller (e.g., controller 150 of processing tool 100). Example processing tools may comprise a processing chamber having one or more gas inlets, an exhaust system fluidically coupled to the processing chamber, the exhaust system comprising at least a throttle valve and a pump situated in a pumping path, and a remote plasma generator fluidically coupled to the exhaust system.

[0077] At 210, method 200 comprises introducing a coating precursor mixture into the pumping path. For example, for carbon deposition tools, the coating precursor mixture may comprise a silicon-containing precursor for generating SiO2 or SiN coatings, as carbon may be selectively etched by a hydrogen or oxygen plasma without removing the silicon-based coating. For example, the silicon containing precursor may comprise one or more of silane and silane derivatives including amino silanes, alkyl silanes with saturated or unsaturated alkyl groups. The coating precursor mixture may further include inert gases. The coating precursor mixture may be introduced into the pumping path via a gas inlet of a processing chamber of the processing tool, the processing chamber fluidically coupled to the pumping path (e.g., via showerheads without generating plasmas). In other examples, the coating precursor mixture may be introduced directly into the pumping path.

[0078] At 220, method 200 comprises introducing a reactant gas mixture into a remote plasma generator fluidically coupled to the exhaust system. The reactant gas mixture may comprise an oxygen-containing gas (e.g., O2, N2O, CO2) and/or may comprise a nitrogen-containing gas (e.g., N2O, NH3). The reactant gas mixture may further comprise an inert gas (e.g., argon or helium). At 230, method 200 comprises generating radical species of the reactant gas mixture at the remote plasma generator. [0079] At 240, method 200 comprises flowing the radical species of the reactant gas into the pumping path. In some examples, the radical species of the reactant gas mixture may be simultaneously introduced into the pumping path with the coating precursor mixture. For example, the coating precursor mixture may be flowed into the exhaust system under PECVD conditions (e.g. simultaneous flow of the reactant gas mixture through the exhaust system and radical species of the reactant gas mixture through direct injection remote plasma apparatus. In other example, the coating precursor mixture may be flowed into the exhaust system under PECVD enhanced ALD conditions (e.g., dosing the coating precursor mixture through the exhaust system, purging the exhaust system, then exposing surfaces saturated with the coating precursor mixture with radical species of the reactant gas mixture through direct injection remote plasma apparatus). The exhaust system may be purged, and the process repeated as desired.

[0080] At 250, method 200 comprises reacting the coating precursor and the reactive species of the reactant gas within the pumping path to form the coating on the surfaces. The coating may be deposited on the throttle, the valve plates, the throttle valve body, the foreline, etc. The coating may be formed as a single layer coating or as multilayer stacks. Depending on the composition of the coating precursor and the reactant gas mixture, the coating may be composed of SiCh, SiN, SiOxNy, SiC, SiOC, or other suitable coating.

[0081] As an example. FIG. 3 schematically illustrates the deposition of a coating of silicon oxide onto surfaces within a pumping path of a PECVD tool, such as processing tool 100. FIG. 3 depicts aspects of processing tool 100 during the application of a coating to surfaces. For example, processing tool 100 comprises an exhaust system 132. Exhaust system 132 comprises a pump 300 and a pumping path 302 extending from processing chamber 102. Throttle valve 133 is located along pumping path 302 between processing chamber 102 and pump 300. A sensor 304, such as an infrared spectrometer, is included in pumping path 302 downstream of throttle valve 133.

[0082] As shown at 310, a coating precursor mixture 124, in this example silane (SiEU), is flowed (310) from coating precursor source 124 via flow control hardware 112. Silane is flowed into pumping path 302 via showerhead 110 in processing chamber 102. However, no plasma is ignited between showerhead 110 and substrate holder 104. Rather, unactivated silane flows into the pumping path. In this example, one showerhead 110 and substrate holder 104 are shown in processing chamber 102, but other examples may have multiple processing stations in a processing chamber. Alternatively silane may be flowed directly to pumping path 302 via conduit 166. Coating precursor mixture 124 may also include an inert carrier gas (not shown).

[0083] As shown at 312, a reactant gas mixture, in this example comprising N2O and Ar, is flowed from remote plasma gas sources 162 (e.g., reactant gas 170 and inert gas 172) into remote plasma generator 160 which is fluidically coupled to exhaust system 132 via conduit 164. Therein, radical species of the reactant gas mixture (e.g., O* and Ar*) are generated as shown at 314. Other biproducts, such as NO*, O3, and N2 may also be formed.

[0084] As shown at 316, O* and Ar* are flowed into pumping path 302 via conduit 164. As shown at 318, 2[O*] and SiT react within pumping path 302 to form SiO2 which coats surfaces of pumping path 302 including throttle valve 133 (e.g., throttle valve plate and throttle valve body). Byproducts and unreacted species may be pumped out of pumping path 302, as shown at 320.

[0085] The coating process in FIG. 3 can be performed by simultaneously flowing the reactant gases and radical species of the reactant gas mixture or by sequentially flowing the reactant gases and the radical species of the reactant gas mixture through the pumping path in a cyclical manner, with an optional purging process between gas flows. By applying such a coating, a significant (e.g., 30%) reduction in non-desired heating of the throttle valve top flange and other components may be realized.

[0086] FIG. 4 shows a flow diagram for an example method 400 of removing and re-applying a coating to surfaces within a pumping path of an exhaust system of a processing tool. Method 200 may be carried out by a controller (e.g., controller 150 of processing tool 100. For example, method 400 may be executed following method 200 or in advance of method 200 for the purposes of removing a prior coating before forming a new coating.

[0087] At 410, method 400 comprises flowing a fluorine containing plasma generated in the remote plasma cleaning system to the pumping path to remove the prior coating. Example fluorine-containing gases include molecular fluorine (F2), hydrogen fluoride (HF), various fluorocarbons (e.g. C_xF_y), hydrofluorocarbons (e.g. C_xH_yF_x), nitrogen trifluoride (NF3), and sulfur fluorides (e.g. sulfur hexafluoride (SFe)). [0088] At 420, method 400 comprises monitoring the exhaust pathway for one or more fluorinated compounds of the coating. For example, the processing tool may comprise an infrared spectrometer positioned within the pumping path upstream of the pump. IR spectroscopy may be used to look for an endpoint indicating that all of the coating material has been removed. For example, for silica coatings, the coating may be converted to SiF using NF3 cleaning/etching. As such, the presence and concentration of SiF and other biproducts such as NF may indicate progress of the etching process towards completion. In the absence of such monitoring, the coating may be deposited, partially cleaned, and deposited again. This may lead to uneven buildup of coating over time. In some scenarios, the coating could become too thick in places and simply peel off the surface.

[0089] In some examples, parabolic mirrors may be positioned near the infrared spectrometer to allow for multiple passes, thus increasing the signal to noise ratio (as the sensor is sensitive to total gas pressure). In other examples, the exhaust pathway may be monitored using other sensors, such as a residual gas analyzer or mass spectrometer.

[0090] At 430, method 400 comprises ceasing flowing the fluorine containing plasma responsive to a concentration of the one or more fluorinated compounds of the coating in the exhaust pathway decreasing below a threshold concentration.

[0091] At 440, method 400 comprises applying a second coating to surfaces within the pumping path of the exhaust system of the processing tool. For example, a coating may be applied using method 200 or similar methods.

Over time, the coating within the pumping path may wear and eventually expose an underlying metal layer. Thus, the coating can be reapplied. In such a reapplication process, remaining coating can first be removed, such as by using a fluorine-based cleaning process. This may help to avoid building up excess coating thicknesses where a prior coating is not fully worn off by use. As an example. FIG. 5 schematically illustrates the deposition of a coating of silicon oxide onto surfaces within a pumping path of a PECVD tool, such as processing tool 100. A fluorine containing plasma may be generated in the remote plasma cleaning system and flowed to the pumping path to remove the prior coating. In this example, NF3 is flowed from fluorine containing gas source 174, as shown at 500. F», NF2*, and N2* radicals are generated at remote plasma generator 160 as shown at 502. The generated fluorine-containing plasma is then flowed to pumping path 302 via conduit 164 as shown at 504. [0092] At 506, the F* radicals are shown reacting with the SiCh coating, thereby generating SiF4. Other biproducts (e.g., SixNyFz, NF3, OF2, HF, SixH_yF_z„ H2O) may also be generated during this etching process, including hydrogen containing compounds, as the SiO2 film will contain some hydrogen. Exhaust pathway 132 may be monitored (e.g., using sensor 304) for one or more fluorinated compounds of the coating (e.g., SiF4). When the concentration of the one or more fluorinated compounds of the coating decreases below a threshold, the cleaning process may be ceased, the exhaust system purged, and a new coating can be applied.

[0093] The disclosed method allows for a flexible approach for changing the surface properties of surfaces within the exhaust system of a processing chamber. The application of a coating to pumping path surfaces as disclosed can offer various advantages compared to coating a component during manufacturing or after removal from a PECVD tool. Components in the system are protected from chemical exposure, and unwanted chemical recombination on surfaces of the exhaust system is reduced. With proper film and chemical selection, various coatings or combinations of coatings can be applied and removed as often as needed without breaking vacuum. This can provide more robust protection than using a same coating for all deposition chemistries used by a PECVD tool, as would occur when using a pre-coated component.

[0094] FIG. 6 schematically shows a non-limiting example of a computing system 600 that can enact one or more of the methods and processes described above. Computing system 600 is shown in simplified form. Computing system 600 may take the form of one or more personal computers, workstations, computers integrated with substrate processing tools, and/or network accessible server computers.

[0095] Computing system 600 includes a logic machine 602 and a storage machine 604. Computing system 600 may optionally include a display subsystem 606, input subsystem 608, communication subsystem 610, and/or other components not shown in FIG. 6. Controller 150 is an example of computing system 600.

[0096] Logic machine 602 includes one or more physical devices configured to execute instructions. For example, the logic machine may be configured to execute instructions that are part of one or more applications, services, programs, routines, libraries, objects, components, data structures, or other logical constructs. Such instructions may be implemented to perform a task, implement a data type, transform the state of one or more components, achieve a technical effect, or otherwise arrive at a desired result. [0097] The logic machine may include one or more processors configured to execute software instructions. Additionally or alternatively, the logic machine may include one or more hardware or firmware logic machines configured to execute hardware or firmware instructions. Processors of the logic machine may be single-core or multi-core, and the instructions executed thereon may be configured for sequential, parallel, and/or distributed processing. Individual components of the logic machine optionally may be distributed among two or more separate devices, which may be remotely located and/or configured for coordinated processing. Aspects of the logic machine may be virtualized and executed by remotely accessible, networked computing devices configured in a cloud-computing configuration.

[0098] Storage machine 604 includes one or more physical devices configured to hold instructions 612 executable by the logic machine to implement the methods and processes described herein. When such methods and processes are implemented, the state of storage machine 604 may be transformed — e.g., to hold different data.

[0099] Storage machine 604 may include removable and/or built-in devices. Storage machine 604 may include optical memory (e.g., CD, DVD, HD-DVD, Blu-Ray Disc, etc.), semiconductor memory (e.g., RAM, EPROM, EEPROM, etc.), and/or magnetic memory (e.g., hard-disk drive, floppy-disk drive, tape drive, MRAM, etc.), among others. Storage machine 604 may include volatile, nonvolatile, dynamic, static, read/write, read-only, random-access, sequential-access, location-addressable, file- addressable, and/or content-addressable devices.

[00100] It will be appreciated that storage machine 604 includes one or more physical devices. However, aspects of the instructions described herein alternatively may be propagated by a communication medium (e.g., an electromagnetic signal, an optical signal, etc.) that is not held by a physical device for a finite duration.

[00101] Aspects of logic machine 602 and storage machine 604 may be integrated together into one or more hardware-logic components. Such hardware-logic components may include field-programmable gate arrays (FPGAs), program- and application-specific integrated circuits (PASIC / ASICs), program- and applicationspecific standard products (PSSP / ASSPs), system-on-a-chip (SOC), and complex programmable logic devices (CPLDs), for example.

[00102] When included, display subsystem 606 may be used to present a visual representation of data held by storage machine 604. This visual representation may take the form of a graphical user interface (GUI). As the herein described methods and processes change the data held by the storage machine, and thus transform the state of the storage machine, the state of display subsystem 606 may likewise be transformed to visually represent changes in the underlying data. Display subsystem 606 may include one or more display devices utilizing virtually any type of technology. Such display devices may be combined with logic machine 602 and/or storage machine 604 in a shared enclosure, or such display devices may be peripheral display devices.

[00103] When included, input subsystem 608 may comprise or interface with one or more user-input devices such as a keyboard, mouse, or touch screen. In some examples, the input subsystem may comprise or interface with selected natural user input (NUI) componentry. Such componentry may be integrated or peripheral, and the transduction and/or processing of input actions may be handled on- or off- board. Example NUI componentry may include a microphone for speech and/or voice recognition, and an infrared, color, stereoscopic, and/or depth camera for machine vision and/or gesture recognition.

[00104] When included, communication subsystem 610 may be configured to communicatively couple computing system 600 with one or more other computing devices. Communication subsystem 610 may include wired and/or wireless communication devices compatible with one or more different communication protocols. As non-limiting examples, the communication subsystem may be configured for communication via a wireless telephone network, or a wired or wireless local- or wide-area network. In some examples, the communication subsystem may allow computing system 600 to send and/or receive messages to and/or from other devices via a network such as the Internet.

[00105] It will be understood that the configurations and/or approaches described herein are exemplary in nature, and that these specific examples or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. As such, various acts illustrated and/or described may be performed in the sequence illustrated and/or described, in other sequences, in parallel, or omitted. Likewise, the order of the above-described processes may be changed.

[00106] The subject matter of the present disclosure includes all novel and non- obvious combinations and sub-combinations of the various processes, systems and configurations, and other features, functions, acts, and/or properties disclosed herein, as well as any and all equivalents thereof.

Claims

CLAIMS:

1. A method of applying a coating to surfaces within a pumping path of an exhaust system of a processing tool, the method comprising: introducing a coating precursor mixture into the pumping path; introducing a reactant gas mixture into a remote plasma generator fluidically coupled to the exhaust system; generating radical species of the reactant gas mixture at the remote plasma generator; flowing the radical species of the reactant gas mixture into the pumping path; and reacting the coating precursor mixture and the reactive species of the reactant gas mixture within the pumping path to form the coating on the surfaces.

2. The method of claim 1, wherein introducing the coating precursor mixture into the pumping path comprises introducing the coating precursor mixture through a gas inlet of a processing chamber of the processing tool, the processing chamber fluidically coupled to the pumping path.

3. The method of claim 1, wherein introducing the coating precursor mixture into the pumping path comprises introducing the coating precursor mixture via the exhaust system upstream of a pump of the pumping path and downstream of a processing chamber of the processing tool.

4. The method of claim 1 , wherein the coating precursor mixture comprises a silicon-containing precursor.

5. The method of claim 4, wherein the coating is a silicon oxide coating.

6. The method of claim 1, wherein the reactant gas mixture comprises an oxygen-containing gas.

7. The method of claim 1, wherein the reactant gas mixture comprises a nitrogen-containing gas.

8. The method of claim 1, further comprising removing a prior coating before forming the coating.

9. The method of claim 8, wherein removing the prior coating comprises flowing a fluorine-containing plasma generated in the remote plasma generator to the pumping path to remove the prior coating.

10. The method of claim 9, further comprising: monitoring the pumping path for one or more fluorinated compounds of the coating; and ceasing flowing the fluorine-containing plasma responsive to a concentration of the one or more fluorinated compounds of the coating in the pumping path decreasing below a threshold concentration.

11. A processing tool, comprising: a processing chamber having one or more gas inlets; an exhaust system fluidically coupled to the processing chamber, the exhaust system comprising at least a throttle valve and a pump situated in a pumping path; a remote plasma generator fluidically coupled to the exhaust system; and a storage machine holding instructions executable by the logic machine to: introduce a coating precursor mixture into the processing chamber via the one or more gas inlets; introduce a reactant gas mixture into a remote plasma generator fluidically coupled to the exhaust system; generate radical species of the reactant gas mixture at the remote plasma generator; flow the radical species of the reactant gas mixture into the pumping path; and react the coating precursor and the reactive species of the reactant gas mixture within the pumping path to form the coating on the surfaces.

12. The processing tool of claim 11, wherein the coating precursor mixture comprises a silicon-containing precursor.

13. The processing tool of claim 12, wherein the coating is a silicon oxide coating.

14. The processing tool of claim 11, wherein the reactant gas mixture comprises an oxygen-containing gas.

15. The processing tool of claim 11, wherein the reactant gas mixture comprises a nitrogen-containing gas.

16. The processing tool of claim 11, wherein the storage machine further holds instructions executable by the logic machine to: flow a fluorine-containing plasma generated in the remote plasma generator to the pumping path to remove a prior coating.

17. The processing tool of claim 16, further comprising a sensor positioned within the pumping path, and wherein the storage machine further holds instructions executable by the logic machine to: cease flowing the fluorine-containing plasma responsive to a concentration of one or more fluorinated compounds of the coating in the exhaust pathway decreasing below a threshold concentration.

18. A method of applying a coating to surfaces within a pumping path of an exhaust system of a processing tool, the method comprising: introducing a first coating precursor mixture into the pumping path; introducing a reactant gas mixture into a remote plasma generator fluidically coupled to the exhaust system; generating radical species of the reactant gas mixture at the remote plasma generator; flowing the radical species of the reactant gas into the pumping path; reacting the first coating precursor mixture and the reactive species of the reactant gas within the pumping path to form a first coating on the surfaces; flowing a fluorine containing plasma generated in the remote plasma generator to the pumping path to remove the first coating; monitoring the exhaust pathway for one or more fluorinated compounds of the first coating; ceasing flowing the fluorine containing plasma responsive to a concentration of the one or more fluorinated compounds of the first coating in the exhaust pathway decreasing below a threshold concentration; and applying a second coating to surfaces within the pumping path of the exhaust system of the processing tool.

19. The method of claim 18, wherein applying a second coating to surfaces within the pumping path of the exhaust system of the processing tool comprises: introducing a second coating precursor mixture into the pumping path; introducing the reactant gas mixture into the remote plasma generator; generating radical species of the reactant gas mixture at the remote plasma generator; flowing the radical species of the reactant gas into the pumping path; and reacting the second coating precursor mixture and the reactive species of the reactant gas within the pumping path to form the second coating on the surfaces.

20. The method of claim 18, wherein the first coating is different from the second coating.