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WO1999006611A1 - Procede et dispositif servant a nettoyer une chambre - Google Patents

Procede et dispositif servant a nettoyer une chambre Download PDF

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Publication number
WO1999006611A1
WO1999006611A1 PCT/US1998/015706 US9815706W WO9906611A1 WO 1999006611 A1 WO1999006611 A1 WO 1999006611A1 US 9815706 W US9815706 W US 9815706W WO 9906611 A1 WO9906611 A1 WO 9906611A1
Authority
WO
WIPO (PCT)
Prior art keywords
chamber
cleaning
inert gas
gas
interior
Prior art date
Application number
PCT/US1998/015706
Other languages
English (en)
Inventor
James T. Gardner
Wendell T. Blonigan
Robert M. Robertson
Original Assignee
Applied Komatsu Technology, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Applied Komatsu Technology, Inc. filed Critical Applied Komatsu Technology, Inc.
Publication of WO1999006611A1 publication Critical patent/WO1999006611A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/4412—Details relating to the exhausts, e.g. pumps, filters, scrubbers, particle traps
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/4401—Means for minimising impurities, e.g. dust, moisture or residual gas, in the reaction chamber
    • C23C16/4405—Cleaning of reactor or parts inside the reactor by using reactive gases

Definitions

  • the present invention relates generally to chemical vapor deposition (CVD) processing, and more particularly to a method and apparatus for CVD chamber cleaning.
  • CVD chemical vapor deposition
  • CVD is widely used in the semiconductor industry to deposit films of various kinds, such as intrinsic and doped amorphous silicon (a-Si), silicon oxide (Si x O y ), silicon nitride (Si r N s ), silicon oxynitride, and the like on a substrate.
  • Modern semiconductor CVD processing is generally done in a vacuum chamber by using precursor gases which dissociate and react to form the desired film.
  • a plasma can be formed from the precursor gases in the chamber during the deposition.
  • Such processes are known as plasma-enhanced CVD processes (PECVD).
  • CVD semiconductor processing chambers are made of aluminum and include a support for the substrate and a port for entry of the required precursor gases.
  • a source of power such as a radio frequency (RF) power source.
  • RF radio frequency
  • a vacuum pump is also connected to the chamber to control the pressure in the chamber and to remove the various gases and particulates generated during the deposition.
  • particulates in the chamber must be kept to a minimum. Particulates are formed because, during the deposition process, the film is deposited not only on the substrate, but also on walls and various fixtures, e.g., shields, the substrate support and the like, in the chamber. During subsequent depositions, the film on the walls, etc., can crack or peel, causing contaminant particles to fall on the substrate. This causes problems and damage to particular devices on the substrate. Damaged devices have to be discarded. >
  • the CVD chamber must be periodically cleaned to remove accumulated films from prior depositions. Cleaning is generally done by introducing an etch gas, such as a fluorine-containing gas, e.g., nitrogen trifluoride (NF 3 ), into the chamber.
  • a fluorine-containing gas e.g., nitrogen trifluoride (NF 3 )
  • NF 3 nitrogen trifluoride
  • a plasma is initiated from the fluorine-containing gas which reacts with coatings from prior depositions on the chamber walls and fixtures, e.g., coatings of a-Si. Si x O y , Si r N s , SiON and the like, as well as any other materials in the chamber.
  • the NF 3 creates free fluorine radicals "F " which react with Si-containing residues.
  • the reaction forms gaseous fluorine-containing volatile products that can be pumped away through the chamber exhaust system. This procedure is generally followed by a nitrogen purge.
  • the preset pressure may be attained prior to endpoint, resulting in an incomplete clean.
  • films may be left in the chamber that are a potential source of contaminant particles.
  • the invention is directed to a method for cleaning a processing chamber. Steps of the method include flowing a cleaning gas into the chamber, and flowing an inert gas into the chamber during at least a portion of the same time as the cleaning gas, such that the ratio of inert gas to cleaning gas is in a range of about 1 : 1 to about 1 :4 by volume.
  • Implementations of the invention may include one or more of the following.
  • the cleaning gas may be NF 3
  • the inert gas may be Ar.
  • the NF may be flowed at a rate between about 6.7 and 13.4 standard cubic centimeters per second per liter of chamber volume, such as about 12.2 standard cubic centimeters per second per liter of chamber volume.
  • the Ar may be flowed at a rate of between about 11.1 and 44.4 standard cubic centimeters per second per liter of chamber volume.
  • the invention is directed to a cleaning system for a processing chamber.
  • the system includes a sensor for measuring total pressure in the interior of the chamber.
  • Two cleaning gas supplies may be used: a cleaning gas supply with a first valved inlet providing an entrance to the interior of the chamber for passing cleaning gas to the interior of the chamber, and an inert gas supply with a second valved inlet providing an entrance to the interior of the chamber for passing an inert gas to the interior of the chamber.
  • a governor with an input coupled to the sensor maintains the total pressure within the chamber at a prespecified value.
  • First and second mass flow controllers are coupled to the first and second valved inlets, such that the first and second mass flow controllers are set to control the ratio of the amount of cleaning gas entering the chamber to the amount of inert gas entering the chamber so that this ratio is maintained in a range of about 1 :1 to 1 :4.
  • the pressure sensor may be a manometer or an ion gauge.
  • An advantage of the invention is that a significantly reduced amount of cleaning gas is necessary to clean a chamber. Less waste of costly NF 3 occurs. Thus, the cleaning process is less expensive.
  • a further advantage is that deposited materials may be removed from walls of a reaction chamber at rates comparable to those using other processes, thus throughput is not sacrificed.
  • Figure 1 is a cross-sectional plan view of a PECVD chamber useful for depositing thin films on a substrate which may be used in accordance with an embodiment of the present invention.
  • the present invention may be used in AKT PECVD systems manufactured by Applied Komatsu Technology of Santa Clara, California.
  • the AKT-3500 PECVD is designed for use in the production of substrates for large liquid crystal flat panel displays. It is a modular system with multiple process chambers which can be used for depositing a-Si, Si r N s , Si x O y , oxynitride films, and other similar films.
  • the present invention may be used with any commercially-available deposition system.
  • substrate to broadly cover any object that is being processed in a process chamber.
  • substrate includes, for example, semiconductor wafers, flat panel displays, and glass plates or disks.
  • the present invention is particularly applicable to large substrates such as glass plates having areas of 360 x 450 mm, 550 x 650 mm, and larger. The remainder of this detailed description describes an embodiment in which a glass substrate is used. However, as noted above, other substrates may also be used.
  • the substrate is supported in a vacuum deposition process chamber, and the substrate is heated to several hundred degrees Celsius (°C).
  • Deposition gases are injected into the chamber, and a plasma-enhanced chemical reaction occurs to deposit a thin film layer onto the substrate.
  • the thin film deposited layer may be a dielectric layer (such as SiN or SiO), a semiconductor layer (such as a-Si) or a metal layer (such as tungsten(W)).
  • a plasma is employed to enhance deposition. Accordingly, appropriate plasma ignition means, such as the RF voltage described below, are generally required. Alternatively, a remote plasma source (not shown) may be used to provide the plasma. More details of a remote plasma chamber may be found in U.S. Patent Application Serial No. 08/707,491, entitled “A Deposition Chamber Cleaning Technique Using a High Power Remote Excitation Source", filed January 14, 1997, assigned to the assignee of the present invention and incorporated herein by reference.
  • a CVD apparatus 130 includes a susceptor 135 having a stem 137.
  • Susceptor 135 is centered within a vacuum deposition process chamber 133.
  • Susceptor 135 holds a substrate such as a glass panel (not shown) in a substrate processing or reaction region 141.
  • a lift mechanism (not shown) is provided to raise and lower the susceptor 135. Commands to the lift mechanism are provided by a controller. Substrates are transferred into and out of chamber 133 through an opening 142 in a sidewall 134 of the chamber 133 by a robot blade (not shown).
  • the deposition process gases flow into chamber 133 through a manifold 61 and an inlet 126.
  • the gases then flow through a perforated blocker plate 124 and a number of holes 121 in a process gas distribution faceplate 122 (indicated by small arrows in the substrate processing region 141 of Figure 1).
  • An RF power supply (not shown) may be used to apply electrical power between gas distribution faceplate 122 and susceptor 135 so as to excite the process gas mixture to form a plasma.
  • the constituents of the plasma react to deposit a desired film on the surface of the substrate on susceptor 135.
  • the deposition process gases may be exhausted from the chamber through a slot- shaped orifice 131 surrounding substrate processing region 141 into an exhaust plenum 150. From exhaust plenum 150, the gases flow by a vacuum shut-off valve 154 and into an exhaust outlet 152 which connects to an external vacuum pump (not shown).
  • Chamber 133 has at least two other gas supplies: an argon (Ar) supply 57 and an NF 3 supply 59. These gases are used for the cleaning procedure.
  • Ar argon
  • a manometer 63 measures the total pressure of gases in chamber 133.
  • manometer 63 could be replaced by numerous other types of sensors for total pressure with equally good results.
  • an ion gauge could be used.
  • a governor 136 is disposed in the exhaust stream to regulate the overall pressure as measured by manometer 63.
  • a signal 151 from manometer 63 may be used as an input to an electrical controller of governor 136 so as to keep the total pressure constant.
  • Chamber 133 may be cleaned by establishing a flow of gas into chamber 133 and creating a plasma therefrom.
  • Ar is established and the system is brought to a temperature such as that used for deposition which may be about 350degrees C to 400degrees C.
  • the gas flow may produce a range of total pressures in the chamber of about 0.1 Torr to about 2.0 Torr, and more particularly about 1 Torr ⁇ 1/2 Torr with a maximum pressure of about 10 Torr.
  • a susceptor-gas manifold spacing of about 500 mil to 2500 mil may be employed.
  • the plasma of gases may be formed either in-situ in the chamber or ex-situ in a remote plasma chamber.
  • gases from the remote plasma chamber enter chamber 133 from a separate valved inlet as described in the patent application incorporated by reference above.
  • the present invention conserves NF 3 by the use of a governor in the chamber exhaust port.
  • the governor varies exhaust conductance in such a manner as to keep the pressure of NF 3 constant within the chamber. In this way, the NF 3 flow rate can be greatly reduced for the same etching rate, and the NF gas is fully utilized in the chamber, eliminating wasted NF 3 .
  • the endpoint of the cleaning procedure is not generally detected using the rise of the chamber total pressure, since the total pressure is by design constant.
  • the present invention can use a low flow rate of NF 3 , such as from about 300 to 800 seem, e.g., about 550 seem.
  • the other gas which may be, like Ar, an inert gas, is also flowed into the chamber simultaneously at a flow rate of from about 500 to 2000 seem, for example 1100 seem.
  • NF 3 rates such as about 6.7 seem to 13.4 seem per liter of chamber volume may be appropriate (such as about 12.2 seem per liter), as may Ar rates of about 11.1 seem to 44.4 seem per liter of chamber volume.
  • NF 3 rates such as 0.15 seem to 0.4 seem per square centimeter of substrate area would be appropriate, as would Ar rates of 0.3 seem to 1.2 seem per square centimeter of substrate area.
  • the rates used should result in a flow rate ratio of NF 3 :Ar in a range of between about 1:1 to 1:4.
  • the flow rates may result in predetermined partial pressures for the cleaning gas and for the inert gas, e.g., for NF 3 and for Ar. These partial pressures may be estimated to first order, in known manner from variables including the flow rates and the overall pressure.
  • An RF power of about 1000 watts to about 4000 watts is applied to the gas manifold to produce a plasma, corresponding to power densities per substrate processing area of about 0.5 watts/cm 2 to about 3 watts/cm 2 .
  • Different deposited materials vary in the rates in which they may be cleaned or removed.
  • the plasma cleans at a rate of about 3000 angstroms per minute to about 4000 angstroms per minute for a-Si, and at a rate of about 6000 angstroms per minute to about 7500 angstroms per minute for SiN.
  • NF 3 and Ar produces a desirable cleaning effect.
  • the chemical mechanisms responsible for the cleaning effect are not well understood.
  • NF 3 diluted with Ar generally dissociates more completely than undiluted NF 3 .
  • Adding an inert, noble or molecular gas to an NF 3 plasma has additional advantages.
  • the discharge is more stable.
  • One reason for this may be that excessive fluorine ion concentrations present in undiluted NF 3 reduce the free electron concentration.
  • a reduction in the free electron concentration is associated with unstable plasmas.
  • Plasma stability is generally desirable and often requires balanced process parameters. These process parameters include gas flow rates, power, pressure, and spacing. Direct relationships exist between the pressure, the free electron temperature, the RF power dissipation, and the free electron concentration. Such relationships may be found in, e.g., Plasma Processing in Semiconductor Electronics. CRC Press, incorporated by reference herein.
  • At least two techniques may be used to determine when the above method has finished cleaning the chamber.
  • an optoelectronic endpoint detector may be used, as described in U.S. Patent Application entitled “Method and Apparatus for Detecting the Endpoint of a Chamber Cleaning", to W. Blonigan and J.T. Gardner, filed on even date herewith, assigned to the assignee of the present invention, and incorporated herein by reference.
  • Ar has been used as the inert gas and NF 3 the cleaning gas.
  • Other inert, noble and molecular gases may also be used, such as helium, neon, krypton, xenon, and molecular nitrogen, as well as other gases with similar properties.
  • other cleaning gases may also be used, such as CF 4 , C 2 F 6 , and SF 6 , as well as other gases with similar cleaning properties. Often these gases will contain fluorine.
  • the cleaning method may be used to clean a number of deposited films.
  • films of Si x Oy, Si r N s , a-Si, polysilicon and SiON may all be removed by the invention.

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Drying Of Semiconductors (AREA)
  • Chemical Vapour Deposition (AREA)

Abstract

Dispositif et procédé servant à nettoyer une chambre de traitement. Ce procédé consiste à introduire un écoulement de gaz de nettoyage vers l'intérieur de la chambre et à introduire un gaz inerte vers l'intérieur de la chambre pendant au moins une partie de la même durée que pour l'écoulement de gaz de nettoyage, de façon à situer le rapport entre le gaz inerte et le gaz de nettoyage dans une plage de 1:1 à 1:4 en volume. Ce dispositif (130) comprend un capteur (63) servant à mesurer la pression totale à l'intérieur de la chambre (133). On peut effectuer deux alimentations en gaz de nettoyage: la première alimentation (59) en gaz de nettoyage étant effectuée par une première entrée vannée constituant une entrée vers l'intérieur de la chambre afin d'y faire pénétrer le gaz de nettoyage et la deuxième alimentation (57) en gaz inerte étant effectuée par une deuxième entrée vannée constituant une entrée vers l'intérieur de la chambre afin d'y faire pénétrer un gaz inerte. Un détendeur (136) comportant une entrée couplée au capteur maintient la pression totale à l'intérieur de la chambre à une valeur prédéterminée. Un première et un deuxième régulateurs de débit-masse sont reliés à la première et à la deuxième entrées vannées, de sorte que ce premier et ce deuxième régulateurs de débit-masse sont réglés afin de réguler le rapport entre la quantité de gaz de nettoyage pénétrant dans la chambre et la quantité de gaz inerte pénétrant dans la chambre, de façon à maintenir ce rapport dans une plage de 1:1 à 1:4.
PCT/US1998/015706 1997-08-01 1998-07-29 Procede et dispositif servant a nettoyer une chambre WO1999006611A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US90465697A 1997-08-01 1997-08-01
US08/904,656 1997-08-01

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WO1999006611A1 true WO1999006611A1 (fr) 1999-02-11

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6843258B2 (en) 2000-12-19 2005-01-18 Applied Materials, Inc. On-site cleaning gas generation for process chamber cleaning
US6880561B2 (en) 2000-03-27 2005-04-19 Applied Materials, Inc. Fluorine process for cleaning semiconductor process chamber

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0638923A2 (fr) * 1993-07-30 1995-02-15 Applied Materials, Inc. Nettoyage à basse température d'appareils CVD à parois froides
US5413670A (en) * 1993-07-08 1995-05-09 Air Products And Chemicals, Inc. Method for plasma etching or cleaning with diluted NF3
EP0731497A2 (fr) * 1995-02-17 1996-09-11 Air Products And Chemicals, Inc. Procédé de nettoyage thermique à l'aide de trifluorure d'azote dilué
US5637153A (en) * 1993-04-30 1997-06-10 Tokyo Electron Limited Method of cleaning reaction tube and exhaustion piping system in heat processing apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5637153A (en) * 1993-04-30 1997-06-10 Tokyo Electron Limited Method of cleaning reaction tube and exhaustion piping system in heat processing apparatus
US5413670A (en) * 1993-07-08 1995-05-09 Air Products And Chemicals, Inc. Method for plasma etching or cleaning with diluted NF3
EP0638923A2 (fr) * 1993-07-30 1995-02-15 Applied Materials, Inc. Nettoyage à basse température d'appareils CVD à parois froides
EP0731497A2 (fr) * 1995-02-17 1996-09-11 Air Products And Chemicals, Inc. Procédé de nettoyage thermique à l'aide de trifluorure d'azote dilué

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6880561B2 (en) 2000-03-27 2005-04-19 Applied Materials, Inc. Fluorine process for cleaning semiconductor process chamber
US6843258B2 (en) 2000-12-19 2005-01-18 Applied Materials, Inc. On-site cleaning gas generation for process chamber cleaning
US6981508B2 (en) 2000-12-19 2006-01-03 Applied Materials, Inc. On-site cleaning gas generation for process chamber cleaning

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