JP2013207057A - Substrate processing apparatus, substrate manufacturing method, and substrate processing apparatus cleaning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning method best suited for an apparatus for forming a silicon carbide film.SOLUTION: A cleaning method, with which a silicon carbide film SIC deposited on a component C-BASE provided inside a reaction chamber is removed, includes: a first step (c) for supplying hydrogen gas Hunder a state where a pressure inside the reaction chamber is set at a first pressure P; and a second step (d) for, after the first step (c), supplying the hydrogen gas Hunder a state where the pressure inside the reaction chamber is set at a second pressure Pthat is higher than the first pressure P.

Description

  The present invention relates to a substrate processing apparatus for processing a substrate, a method for manufacturing a semiconductor device, a method for manufacturing a substrate, and a cleaning method for a substrate processing apparatus, and in particular, a silicon carbide (hereinafter referred to as SiC) epitaxial film on a substrate. The present invention relates to a substrate processing apparatus having a step of forming a film, a semiconductor device manufacturing method, a substrate manufacturing method, and a substrate processing apparatus cleaning method.

  SiC is attracting attention as an element material for power devices. On the other hand, it is known that SiC is more difficult to produce a crystal substrate and a device than silicon (hereinafter referred to as Si).

  On the other hand, when manufacturing a device using SiC, a wafer in which a SiC epitaxial film is formed on a SiC substrate is used. As an example of a SiC epitaxial growth apparatus for forming a SiC epitaxial film on this SiC substrate, there is Patent Document 1.

  As described in Patent Document 1, in order to grow a SiC epitaxial film on a SiC substrate, it is necessary to heat to a high temperature of about 1600 degrees. Therefore, parts located in the processing furnace heated to high temperature are often formed of carbon having high heat resistance.

JP 2011-388A

  Here, the parts in the processing furnace are exposed to the material gas in the same way as the wafer during the SiC epitaxial growth process. For this reason, a SiC film is also deposited on the surface of the component in the processing furnace. If this SiC film is deposited more than a certain thickness, it will be peeled off due to the difference in thermal expansion coefficient from the surface of the part formed of carbon. If the peeled SiC film adheres to the wafer surface, the epitaxial growth is hindered, and the quality of the epitaxial film is deteriorated. For this reason, before the SiC film adhering to the component is peeled off, the component itself is replaced or a mechanical cleaning process (scraping off the SiC film) is performed. In order to carry out this work, there is a problem in that the parts from the apparatus must be removed and reassembled, which reduces the productivity of the apparatus. In addition, there is a problem that the replacement cost of the in-furnace member increases.

  According to one aspect of the present invention, there is provided a cleaning method for removing a silicon carbide film deposited on a member provided in a reaction chamber, wherein the first gas is supplied with hydrogen gas in a state where the pressure in the reaction chamber is set to a first pressure. And a second step of supplying the hydrogen gas in a state where the pressure in the reaction chamber is set to a second pressure higher than the first pressure after the first step.

  According to another aspect of the present invention, a reaction chamber in which a substrate to be processed on which a silicon carbide film is formed is placed, a first member provided in the reaction chamber, and the reaction chamber. At least one of a plurality of gas supply systems for supplying a deposition gas for forming the silicon carbide film on the substrate to be processed, an exhaust system for exhausting the atmosphere of the reaction chamber, and the plurality of gas supply systems And supplying the hydrogen gas to the reaction chamber and controlling the plurality of gas supply systems and the exhaust system so that the pressure in the reaction chamber becomes the first pressure, and then at least one of the plurality of gas supply systems A substrate process comprising: a plurality of gas supply systems, and a controller for controlling the exhaust system so that hydrogen gas is supplied from one and the pressure in the reaction chamber becomes a second pressure higher than the first pressure. An apparatus is provided.

  An improved cleaning method is provided.

1 is a perspective view of a semiconductor manufacturing apparatus to which the present invention is applied. It is side surface sectional drawing of the processing furnace to which this invention is applied. It is a plane sectional view of a processing furnace to which the present invention is applied. It is a figure explaining the gas supply unit of the semiconductor manufacturing apparatus with which this invention is applied. It is a block diagram which shows the control structure of the semiconductor manufacturing apparatus with which this invention is applied. It is a table | surface explaining the principle of this invention. It is the schematic which shows the cleaning method of this invention. It is a cross-sectional SEM photograph at the time of applying the cleaning method of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, a so-called batch type vertical SiC epitaxial growth apparatus in which SiC wafers are arranged in the height direction in a SiC epitaxial growth apparatus which is an example of a substrate processing apparatus will be described. In addition, by setting it as a batch type vertical SiC epitaxial growth apparatus, the number of the SiC wafers which can be processed at once increases and a throughput improves.

<Overall configuration>
First, referring to FIG. 1, a substrate processing apparatus for forming a SiC epitaxial film according to the first embodiment of the present invention, and a substrate for forming a SiC epitaxial film which is one of semiconductor device manufacturing steps. The manufacturing method will be described.

  A semiconductor manufacturing apparatus 10 as a substrate processing apparatus (film forming apparatus) is a batch type vertical heat treatment apparatus, and includes a housing 12 in which a main part is arranged. In the semiconductor manufacturing apparatus 10, a hoop (hereinafter referred to as a pod) 16 is used as a wafer carrier as a substrate container for storing a wafer 14 (see FIG. 2) as a substrate made of, for example, SiC. A pod stage 18 is disposed on the front side of the housing 12, and the pod 16 is conveyed to the pod stage 18. For example, 25 wafers 14 are stored in the pod 16 and set on the pod stage 18 with the lid closed.

  A pod transfer device 20 is disposed in a front face of the housing 12 and at a position facing the pod stage 18. A pod storage shelf 22, a pod opener 24, and a substrate number detector 26 are disposed in the vicinity of the pod transfer device 20. The pod storage shelf 22 is disposed above the pod opener 24 and is configured to hold a plurality of pods 16 mounted thereon. The substrate number detector 26 is disposed adjacent to the pod opener 24, and the pod transfer device 20 transfers the pod 16 among the pod stage 18, the pod storage shelf 22, and the pod opener 24. The pod opener 24 opens the lid of the pod 16, and the substrate number detector 26 detects the number of wafers 14 in the pod 16 with the lid opened.

  A substrate transfer machine 28 and a boat 30 as a substrate holder are disposed in the housing 12. The substrate transfer machine 28 has an arm (tweezer) 32, and has a structure that can be moved up and down and rotated by a driving means (not shown). The arm 32 can take out, for example, five wafers 14. By moving the arm 32, the wafer 14 is transferred between the pod 16 and the boat 30 placed at the position of the pod opener 24.

  The boat 30 is made of a heat-resistant material such as carbon graphite or SiC, for example, and a plurality of wafers 14 are arranged in a horizontal posture and aligned with their centers aligned, and are stacked and held in the vertical direction. It is configured. A boat heat insulating portion 34 is disposed as a hollow cylindrical heat insulating member made of a heat resistant material such as quartz or SiC at the lower portion of the boat 30, and heat from the heated body 48 to be described later is received. It is comprised so that it may become difficult to be transmitted to the downward side of the processing furnace 40 (refer FIG. 2).

  The processing furnace 40 is disposed in the upper part on the back side in the housing 12. The boat 30 loaded with a plurality of wafers 14 is loaded into the processing furnace 40 and subjected to heat treatment.

<Processing furnace configuration>
Next, referring to FIGS. 2, 3, and 4, the processing furnace 40 of the semiconductor manufacturing apparatus 10 for forming a SiC epitaxial film will be described. The processing furnace 40 is provided with a first gas supply nozzle 60 having a first gas supply port 68, a second gas supply nozzle 70 having a second gas supply port 72, and a first gas exhaust port 90. It is done. In addition, a third gas supply port 360 and a second gas exhaust port 390 for supplying an inert gas are shown.

  The processing furnace 40 is made of a heat resistant material such as quartz or SiC, and includes a reaction tube 42 formed in a cylindrical shape having a closed upper end and an opened lower end. Below the reaction tube 42, a manifold 36 is disposed concentrically with the reaction tube 42. The manifold 36 is made of, for example, stainless steel and is formed in a cylindrical shape with an upper end and a lower end opened. The manifold 36 is provided to support the reaction tube 42. An O-ring (not shown) as a seal member is provided between the manifold 36 and the reaction tube 42. Since the manifold 36 is supported by a holding body (not shown), the reaction tube 42 is installed vertically. A reaction vessel is formed by the reaction tube 42 and the manifold 36.

  The processing furnace 40 includes a derivative 48 formed in a cylindrical shape with an upper end closed and a lower end opened, and an induction coil 50 as a magnetic field generation unit. A reaction chamber 44 is formed in a cylindrical hollow portion of the to-be-derivatized 48 so that the boat 30 holding the wafer 14 as a substrate made of SiC or the like can be accommodated. The derivative 48 and the induction coil 50 constitute a heating unit. The heating unit will be described in detail later.

  As shown in the lower frame of FIG. 2, the wafer 14 is held by the annular lower wafer holder 15 and held by the boat 30 with the upper surface covered by the disk-like upper wafer holder 15 a. Good. Thereby, the wafer 14 can be protected from particles falling from the upper part of the wafer, and film formation on the back surface side with respect to the film formation surface (lower surface of the wafer 14) can be suppressed. Further, the film forming surface can be separated from the boat column of the wafer holder 15, and the influence of the boat column can be reduced. The boat 30 is configured to hold the wafers 14 held by the wafer holder 15 so as to be aligned in the vertical direction in a horizontal posture and with the centers aligned. The derivative 48 is heated by a magnetic field generated by an induction coil 50 provided outside the reaction tube 42, and the reaction chamber 44 is heated when the derivative 48 generates heat. It is like.

  In the vicinity of the derivative 48, a temperature sensor (not shown) is provided as a temperature detector that detects the temperature in the reaction chamber 44. The induction coil 50 and the temperature sensor are electrically connected to the temperature control unit 52, and the inside of the reaction chamber 44 is adjusted by adjusting the degree of energization to the induction coil 50 based on the temperature information detected by the temperature sensor. The temperature is controlled at a predetermined timing so as to obtain a desired temperature distribution (see FIG. 5).

  Preferably, in the reaction chamber 44, between the first and second gas supply nozzles 60, 70 and the first gas exhaust port 90, and between the heated object 48 and the wafer 14. In the meantime, a structure 300 extending in the vertical direction and having an arc-shaped cross section is preferably provided in the reaction chamber 44 so as to fill the space between the heated object 48 and the wafer 14. For example, as shown in FIG. 3, by providing the structures 300 at the opposing positions, the gas supplied from the first and second gas supply nozzles 60 and 70 is transferred along the inner wall of the derivative 48 to the wafer. Bypassing 14 can be prevented. When the structure 300 is preferably made of carbon graphite or the like, heat resistance and generation of particles can be suppressed.

  Between the reaction tube 42 and the to-be-derivatized 48, a heat insulating material 54 made of, for example, a carbon felt that is not easily dielectric is provided. By providing the heat insulating material 54, the heat of the to-be-derivatized 48 is changed to the reaction tube 42 or Can suppress the transmission to the outside of the reaction tube 42.

  Further, an outer heat insulating wall 55 having, for example, a water cooling structure is provided outside the induction coil 50 so as to suppress the heat in the reaction chamber 44 from being transmitted to the outside so as to surround the reaction chamber 44. Further, a magnetic seal 58 for preventing the magnetic field generated by the induction coil 50 from leaking outside is provided outside the outer heat insulating wall 55.

  As shown in FIG. 2, a first gas supply nozzle 60 provided with at least one first gas supply port 68 is installed between the derivative 48 and the wafer 14. Further, a second gas supply nozzle 70 provided with at least one second gas supply port 72 is provided at a location different from the first gas supply nozzle 60 between the derivative 48 and the wafer 14. . Similarly, the first gas exhaust port 90 is also disposed between the heated object 48 and the wafer 14. In addition, a third gas supply port 360 and a second gas exhaust port 390 are disposed between the reaction tube 42 and the heat insulating material 54. The gas types supplied from the first gas supply nozzle 60 and the second gas supply nozzle 70 will be described later.

  The first gas supply port 68 and the first gas supply nozzle 60 are made of, for example, carbon graphite and are provided in the reaction chamber 44. The first gas supply nozzle 60 is attached to the manifold 36 so as to penetrate the manifold 36. The first gas supply nozzle 60 is connected to the gas supply unit 200 via the first gas line 222.

  The second gas supply port 72 is made of, for example, carbon graphite and is provided in the reaction chamber 44. The second gas supply nozzle 70 is attached to the manifold 36 so as to penetrate the manifold 36. Further, the second gas supply nozzle 70 is connected to the gas supply unit 200 via the second gas line 260.

  Further, in the first gas supply nozzle 60 and the second gas supply nozzle 70, one first gas supply port 68 and one second gas supply port 72 may be provided in the arrangement region of the substrate. Alternatively, it may be provided for every predetermined number of wafers 14.

  As described above, at least the boat 30 and the nozzles 60 and 70 provided in the reaction chamber 44 are preferably formed of carbon graphite, which is a heat resistant material, so as to withstand temperatures of about 1600 degrees. In that case, if the carbon graphite is exposed as it is, it may react with the processing gas and the like, which may cause generation of particles. Therefore, it is desirable to coat it with a SiC film.

<Exhaust system>
As shown in FIG. 2, a first gas exhaust port 90 is provided below the boat 30, and a gas exhaust pipe 230 connected to the first gas exhaust port 90 is provided in the manifold 36 so as to pass therethrough. It has been. A vacuum exhaust device 220 such as a vacuum pump is connected to the downstream side of the gas exhaust pipe 230 via a pressure sensor (not shown) as a pressure detector and an APC (Auto Pressure Controller) valve 214 as a pressure regulator. Yes. A pressure control unit 98 is electrically connected to the pressure sensor and the APC valve 214, and the pressure control unit 98 adjusts the opening degree of the APC valve 214 based on the pressure detected by the pressure sensor, thereby processing furnace. Control is performed at a predetermined timing so that the pressure in 40 becomes a predetermined pressure (see FIG. 5).

  As described above, the gas supplied from the first gas supply port 68 and the second gas supply port 72 flows in parallel to the wafer 14 made of Si or SiC, and is exhausted from the first gas exhaust port 90. Therefore, the entire wafer 14 is exposed to the gas efficiently and uniformly.

  A boat heat insulating portion 34A is provided under the boat 30 so that the manifold 36 and the like are not heated by the radiant heat from the reaction chamber. Further, in the present embodiment, heat exchange is performed to reduce the temperature of the deposition gas by performing heat exchange with the deposition gas so that the deposition gas heated in the reaction chamber does not reach the manifold 36 or the like at a high temperature. Is provided. Specifically, the boat heat insulating portion 34A has a hollow cylindrical shape, and the film forming gas is exhausted along the side surface. Moreover, the 2nd heat exchange part provided in the lower part of the 1st heat exchange part 34B and the gas supply nozzle 60 (70) is provided so that the said boat heat insulation part 34A may be enclosed. The first heat exchange unit 34B and the second heat exchange unit 34C are arranged so as to have a gap with the boat heat insulating unit 34A, and the flow of the film forming gas in the reaction chamber flows through the flow path of the film forming gas to be exhausted. It is narrower than the road. Thereby, since the film forming gas is exhausted through the narrow flow path, the efficiency of heat exchange is further improved.

  As shown in FIG. 3, the third gas supply port 360 is disposed between the reaction tube 42 and the heat insulating material 54 and attached so as to penetrate the manifold 36. Further, the second gas exhaust port 390 is disposed between the reaction tube 42 and the heat insulating material 54 so as to face the third gas supply port 360, and the second gas exhaust port 390 is a gas It is connected to the exhaust pipe 230. The third gas supply port 360 is formed in a third gas line 240 that penetrates the manifold 36, and the third gas line is connected to the gas supply unit 200. As shown in FIG. 4, the third gas line is connected to a gas supply source 210f via a valve 212f and an MFC 211f. For example, a rare gas Ar gas is supplied as an inert gas from the gas supply source 210f, and a gas contributing to the growth of the SiC epitaxial film is prevented from entering between the reaction tube 42 and the heat insulating material 54. It is possible to prevent unnecessary products from adhering to the inner wall of 42 or the outer wall of the heat insulating material 54.

  Further, the inert gas supplied between the reaction tube 42 and the heat insulating material 54 is exhausted from the vacuum exhaust device 220 via the APC valve 214 on the downstream side of the gas exhaust tube 230 from the second gas exhaust port 390. Is done.

<Details of gas supplied to each gas supply system>
Next, the first gas supply system and the second gas supply system will be described with reference to FIG. As shown in FIG. 4, the first gas line 222 includes mass flow controllers (hereinafter referred to as MFC) 211a and 211b as flow rate controllers (flow rate control means) for SiH 4 gas, HCl gas, and inert gas. , 211c and valves 212a, 212b, 212c, for example, are connected to an SiH4 gas supply source 210a, an HCl gas supply source 210b, and an inert gas supply source 210c.

  With the above configuration, the supply flow rate, concentration, partial pressure, and supply timing of SiH 4 gas, HCl gas, and inert gas can be controlled in the reaction chamber 44. The valves 212a, 212b, and 212c and the MFCs 211a, 211b, and 211c are electrically connected to the gas flow rate control unit 78, and are controlled at a predetermined timing so that the flow rate of the supplied gas becomes a predetermined flow rate. (See FIG. 5). Note that SiH 4 gas, HCl gas, and inert gas supply sources 210 a, 210 b, 210 c, valves 212 a, 212 b, 212 c, MFC 211 a, 211 b, 211 c, first gas line 222, first gas supply nozzle 60 A first gas supply system is configured as a gas supply system by at least one first gas supply port 68 provided in the first gas supply nozzle 60.

  Further, the second gas line 260 is connected to the C3H8 gas supply source 210d through the MFC 211d and the valve 212d as a flow rate control unit for C3H8 gas, for example, as C (carbon) atom-containing gas, and as the reducing gas, For example, the H2 gas is connected to the H2 gas supply source 210e via the MFC 211e as a flow rate control means and a valve 212e.

  With the above configuration, the supply flow rate, concentration, and partial pressure of C3H8 gas and H2 gas can be controlled in the reaction chamber 44. The valves 212d and 212e and the MFCs 211d and 211e are electrically connected to the gas flow rate control unit 78, and are controlled at a predetermined timing so that the supplied gas flow rate becomes a predetermined flow rate ( (See FIG. 5). Gas supply is provided by gas supply sources 210d and 210e of C3H8 gas and H2 gas, valves 212d and 212e, MFCs 211d and 211e, a second gas line 260, a second gas supply nozzle 70, and a second gas supply port 72. A second gas supply system is configured as the system.

  Thus, by supplying the Si atom-containing gas and the C atom-containing gas from different gas supply nozzles, it is possible to prevent the SiC film from being deposited in the gas supply nozzle. Further, hydrogen gas that is a reducing gas is supplied through a second gas supply nozzle 70 that supplies a C atom-containing gas in order to suppress decomposition of the Si atom-containing gas in the nozzle. In this case, the reducing gas can be used as a carrier gas for the C atom-containing gas. Note that the use of an inert gas (particularly a rare gas) such as argon (Ar) as the carrier of the Si atom-containing gas can suppress the deposition of the Si film. Further, a chlorine atom containing gas such as HCl is supplied to the first gas supply nozzle 60. In this way, even if the Si atom-containing gas is decomposed by heat and can be deposited in the first gas supply nozzle, it becomes possible to enter the etching mode with chlorine, and the first gas supply nozzle It is possible to further suppress the deposition of the Si film inside. Further, the chlorine atom-containing gas also has an effect of etching the deposited film, and the first gas supply port 68 can be prevented from being blocked.

  In addition, although HCl gas was illustrated as Cl (chlorine) atom containing gas flowed when forming a SiC epitaxial film, you may use chlorine gas.

  In the above description, when the SiC epitaxial film is formed, a Si (silicon) atom-containing gas and a Cl (chlorine) atom-containing gas are supplied. However, a gas containing Si atoms and Cl atoms, for example, tetrachlorosilane (hereinafter referred to as SiCl4 and Gas), trichlorosilane (hereinafter referred to as SiHCl3) gas, and dichlorosilane (hereinafter referred to as SiH2Cl2) gas may be supplied. Needless to say, the gas containing Si atoms and Cl atoms is also a Si atom-containing gas or a mixed gas of Si atom-containing gas and Cl atom-containing gas. In particular, SiCl4 is desirable from the viewpoint of suppressing the consumption of Si in the nozzle because the temperature at which it is thermally decomposed is relatively high.

  In the above description, C3H8 gas is exemplified as the C (carbon) atom-containing gas. However, ethylene (hereinafter referred to as C2H4) gas or acetylene (hereinafter referred to as C2H2) gas may be used.

  Moreover, although H2 gas was illustrated as reducing gas, it is not restricted to this, You may use other H (hydrogen) atom containing gas. Furthermore, as the carrier gas, at least one of rare gases such as Ar (argon) gas, He (helium) gas, Ne (neon) gas, Kr (krypton) gas, and Xe (xenon) gas may be used. Alternatively, a mixed gas in which the above gases are combined may be used.

<Control unit>
Next, referring to FIG. 5, the control configuration of each part constituting the semiconductor manufacturing apparatus 10 for forming a SiC epitaxial film will be described.

  The temperature control unit 52, the gas flow rate control unit 78, the pressure control unit 98, and the drive control unit 108 constitute an operation unit and an input / output unit, and are electrically connected to a main control unit 150 that controls the entire semiconductor manufacturing apparatus 10. ing. The temperature control unit 52, the gas flow rate control unit 78, the pressure control unit 98, and the drive control unit 108 are configured as a controller 152.

<Method of forming SiC film>
Next, as a step of the semiconductor device manufacturing process using the semiconductor manufacturing apparatus 10 described above, a substrate manufacturing method for forming, for example, a SiC film on a substrate such as a wafer 14 made of SiC or the like will be described. In the following description, the operation of each part constituting the semiconductor manufacturing apparatus 10 is controlled by the controller 152.

  First, when the pod 16 storing a plurality of wafers 14 is set on the pod stage 18, the pod 16 is transferred from the pod stage 18 to the pod storage shelf 22 by the pod transfer device 20 and stocked. Next, the pod 16 stocked on the pod storage shelf 22 is transported and set to the pod opener 24 by the pod transport device 20, the lid of the pod 16 is opened by the pod opener 24, and the pod 16 is detected by the substrate number detector 26. The number of wafers 14 housed in is detected.

  Next, the wafer 14 is taken out from the pod 16 at the position of the pod opener 24 by the substrate transfer device 28 and transferred to the boat 30.

  When a plurality of wafers 14 are loaded into the boat 30, the boat 30 holding the wafers 14 is loaded into the reaction chamber 44 (boat loading) by the lifting and lowering operation of the lifting platform 114 and the lifting shaft 124 by the lifting motor 122. . In this state, the seal cap 102 is in a state of sealing the lower end of the manifold 36 via an O-ring (not shown).

  After the boat 30 is loaded, the reaction chamber 44 is evacuated by the evacuation device 220 so that the inside of the reaction chamber 44 has a predetermined pressure (degree of vacuum). At this time, the pressure in the reaction chamber 44 is measured by a pressure sensor (not shown), and the APC valve 214 communicating with the first gas exhaust port 90 and the second gas exhaust port 390 based on the measured pressure is used. Feedback controlled. Further, the derivative 48 is heated so that the inside of the wafer 14 and the reaction chamber 44 has a predetermined temperature. At this time, the current supply to the induction coil 50 is feedback controlled based on temperature information detected by a temperature sensor (not shown) so that the reaction chamber 44 has a predetermined temperature distribution. Further, the amount of heat generated by the derivative is heated so that the upper end side and the lower end side are higher than the central portion. Thereby, soaking in the reaction chamber is ensured. Subsequently, when the boat 30 is rotated by the rotation mechanism 104, the wafer 14 is rotated in the circumferential direction.

  Subsequently, Si (silicon) atom-containing gas and Cl (chlorine) atom-containing gas contributing to the SiC epitaxial growth reaction are supplied from gas supply sources 210a and 210b, respectively, and the reaction chamber 44 is supplied from the first gas supply port 68. Erupted inside. Further, after the opening degrees of the corresponding MFCs 211d and 211e are adjusted so that the C (carbon) atom-containing gas and the reducing gas H2 gas have a predetermined flow rate, the valves 212d and 212e are opened, The gas flows through the second gas line 260, flows through the second gas supply nozzle 70, and is introduced into the reaction chamber 44 through the second gas supply port 72.

  The gas supplied from the first gas supply port 68 and the second gas supply port 72 passes through the inside of the derivative 48 in the reaction chamber 44 and passes through the gas exhaust pipe 230 from the first gas exhaust port 90. Exhausted. When the gas supplied from the first gas supply port 68 and the second gas supply port 72 passes through the reaction chamber 44, the gas contacts the wafer 14 made of SiC or the like, and the SiC is formed on the surface of the wafer 14. Epitaxial film growth is performed.

  Further, after the opening of the corresponding MFC 211f is adjusted by the gas supply source 210f so that the Ar gas, which is a rare gas as an inert gas, has a predetermined flow rate, the valve 212f is opened and the third gas line is opened. 240 is supplied to the reaction chamber 44 from the third gas supply port 360. Ar gas which is a rare gas as an inert gas supplied from the third gas supply port 360 passes between the heat insulating material 54 in the reaction chamber 44 and the reaction tube 42, and the second gas exhaust port 390. Exhausted from.

  Next, when a preset time elapses, the gas supply described above is stopped, an inert gas is supplied from an inert gas supply source (not shown), and the space inside the object to be heated 48 in the reaction chamber 44 becomes empty. While being replaced with the inert gas, the pressure in the reaction chamber 44 is returned to normal pressure.

  Thereafter, the seal cap 102 is lowered by the elevating motor 122, the lower end of the manifold 36 is opened, and the processed wafer 14 is carried out from the lower end of the manifold 36 to the outside of the reaction tube 42 while being held in the boat 30 ( The boat 30 waits at a predetermined position until the wafer 14 held in the boat 30 cools. When the wafers 14 in the boat 30 that have been waiting are cooled to a predetermined temperature, the wafers 14 are taken out from the boat 30 by the substrate transfer device 28, and transferred to the empty pod 16 set in the pod opener 24 for storage. To do. Thereafter, the pod 16 in which the wafers 14 are stored is transferred to the pod storage shelf 22 or the pod stage 18 by the pod transfer device 20. In this way, a SiC film is formed on the wafer 14. In addition, a cleaning process described later is performed every time the SiC film forming process is performed once or after being repeated a plurality of times.

<Cleaning method>
First, the principle of the gas cleaning method of the present invention will be described. The gas cleaning method of the present invention is performed using hydrogen (H2). The chemical reaction that occurs when mixed with the SiC film present in the reaction chamber 44 has several forms, but is typically represented by the formula (1).
2SiC + 3H2 → 2SiH2 ↑ + C2H2 ↑ (1)
As described above, SiC reacts with SiC and H2 is decomposed and can be etched. However, for example, under low pressure conditions, SiH2 can be efficiently evacuated and thus Si etching is promoted. However, since the H2 concentration is low, C etching is slowed down, and porous carbon (hereinafter referred to as “porous carbon”) is produced. It may remain.

  FIG. 6 shows the etching rate of SiC by H 2 and the residual amount of porous carbon on the SiC surface. As shown in FIG. 6, when the flow rate of H2 is high at a predetermined temperature, the etching rate of SiC is large. Therefore, the cleaning process may be performed under conditions where the flow rate of H2 is fast. However, since there is a settable range for the flow rate and pressure of H2 (capacity of the vacuum pump), it is difficult to obtain a sufficient flow rate.

  Therefore, in the present invention, even if the flow rate is slow, the etching amount of SiC is moderately large at low pressure, and the etching amount of SiC is very small at high pressure. Focusing on the fact that the residual porous carbon is very small, cleaning is performed with the inside of the reaction chamber 44 in a low pressure P1 state, and then cleaning is performed with the inside of the reaction chamber 44 in a high pressure P2 (> P1) state. Details will be described below.

  Next, the cleaning method according to the present invention will be described. FIG. 7 is a diagram showing an outline of the cleaning method according to the present invention. These gas supply operations are controlled by the controller 152 of FIG. Parts located in the reaction chamber such as the first and second gas supply nozzles 60 and 70, the first and second gas supply ports 62 and 72, the boat 30, and the heated body 48 located in the reaction chamber 44 are A carbon base material C-BASE (carbon graphite base material) having high heat resistance because it is heated to a high temperature is used. Further, when the SiC epitaxial film is formed, carbon is etched and coated with a SiC film SIC to prevent particles from being formed (FIG. 7A). When the SiC epitaxial film is formed, the SiC epitaxial film is formed thereon. Further, a SiC film SIC is deposited (FIG. 7B). When the SiC epitaxial film deposition process is repeated, the SiC film becomes thicker on the surface. A gas cleaning step is performed when the SiC film SIC on the surface reaches a certain thickness (not causing film peeling) (about 200 to 300 μm).

  In the gas cleaning step, first, the wafer holders 15 on which the wafers 14 are not set are transferred to a plurality of boats, and then the boats are raised to seal the reaction chamber 44. The wafer holder 15 may be cleaned by a method different from that of the substrate processing apparatus 10 without being subjected to gas cleaning. Next, a reduced pressure purge is performed in the reaction chamber at a desired flow rate and pressure with an inert gas such as argon (Ar) to reduce the impurity concentration in the reaction chamber. At the same time, an electric current is passed through the induction coil 50 to heat the derivative 48 by induction heating, thereby heating the reaction chamber 44. Further, by exhausting the heated atmosphere in the reaction chamber 44 from the exhaust port 90, the gas exhaust pipe 230 is heated, and the members in the reaction chamber 44 are maintained at a desired temperature.

  Next, after the temperature in the reaction chamber 44 is stabilized, the vacuum exhaust device 220 and the APC valve 214 are controlled to set the pressure in the reaction chamber 44 to a relatively low pressure P1 (for example, 50 Pa to 500 Pa). Thereafter, by controlling the MFC 211e and the valve 212e, the hydrogen gas H2 is supplied into the reaction chamber 44 via the second gas line (low pressure region cleaning step). When hydrogen gas is supplied for a predetermined time, the surface of the SiC film SIC is etched and porous carbon C-POR remains (FIG. 7C).

  Next, the vacuum exhaust device 220 and the APC valve 214 are controlled to set the pressure in the reaction chamber to a relatively high pressure P2 (for example, 3000 Pa to 10000 Pa). Until the pressure stabilizes, the supply of hydrogen gas may be stopped by controlling the MFC 211e and the valve 212e, but the cleaning time can be shortened by continuing. In this state, when a predetermined time elapses, the surface of the porous carbon C-POR is etched. On the other hand, since the inside of the reaction chamber 44 is at a high pressure, the hydrogen gas easily passes through the gap between the porous carbons and reaches the SiC film SIC existing under the porous carbon C-POR. As a result, the interface between the SiC film SIC and the porous carbon C-POR is also etched, and the porous carbon C-POR and the SiC film SIC are separated (FIG. 7D) (high-pressure cleaning process). The separated porous carbon C-POR is discharged from the gas exhaust pipe 230 via the exhaust port 90. In the cleaning in the high pressure state, the vacuum exhaust device 220 and the APC valve 214 may be controlled to repeatedly perform a state in which almost no exhaust (a state in which H2 gas is confined) and a state in which exhaust is performed. However, it is thought that the porous carbon C-POR separated efficiently can be exhausted by continuing the exhaust.

  Next, so-called cycle purge PRG is performed in which supply of hydrogen gas or inert gas (for example, argon (Ar)) and exhaust are repeated. Thereby, pressure fluctuation occurs in the reaction chamber 44, and the porous carbon C-POR separated from the SiC film SIC can be efficiently exhausted. Thereby, it can be set as the state which coated the thin SiC film | membrane SIC on the carbon graphite base material C-BASE (FIG.7 (e)). Then, the SiC film forming process is performed again.

FIG. 8 shows cross-sectional SEM photographs in the states of FIGS. 7 (c) and 7 (d). FIG. 8A corresponds to the state of FIG. 7C, and FIG. 8B corresponds to the state of FIG. 7D. The processing conditions are as follows.
1. Cleaning process in low pressure region Temperature: 1800 ° C., hydrogen flow rate: 10 slm, pressure: 150 Pa
2. Cleaning process in high pressure region Temperature: 1700 ° C., hydrogen flow rate: 10 slm, pressure: 5000 Pa
As can be seen from FIG. 8A, it can be seen that the porous carbon C-POR remains on the surface of the SiC film SIC by performing the cleaning in the low pressure region. Further, as can be seen from FIG. 8B, it can be seen that the interface between the porous carbon C-POR and the SiC film SIC is separated by performing the cleaning in the high pressure region.

  In the present invention, the separated porous carbon is exhausted from the gas exhaust pipe 230, but the separated porous carbon may remain in the gas exhaust pipe 230. In that case, oxygen gas can be directly supplied to the gas exhaust pipe 230 and heated to a predetermined temperature to be discharged as carbon dioxide.

  Further, there may be a case where sufficient cleaning cannot be performed even if the cleaning process for the low pressure region and the cleaning process for the high pressure region are performed once each. In that case, sufficient cleaning can be achieved by repeating the cleaning process for the low pressure region and the cleaning process for the high pressure region a plurality of times. In this case, a cycle purge process is also performed, and the porous carbon C-POR is separated again after exhausting the separated porous carbon C-POR from the reaction chamber.

As described above, according to the present embodiment, at least one of the following effects is provided.
(1) In the cleaning process, the first cleaning process for supplying hydrogen gas with the reaction chamber set to the first pressure, and the hydrogen gas supplied with the reaction chamber set to the second pressure higher than the first pressure. By dividing into the second cleaning step, the cleaning time can be shortened without adopting a special structure capable of increasing the processing temperature or increasing the flow rate of the H2 gas.

(2) In the above (1), the so-called cycle purge in which the gas supply and the exhaust are repeated after the second cleaning step can efficiently discharge the porous carbon separated in the second cleaning step.

(3) In the above (1) or (2), the first cleaning step and the second cleaning step are repeated a predetermined number of times, so that the cleaning can be performed even if the SiC film to be cleaned is thick.

(4) In the above (3), by repeating the first cleaning process, the second cleaning process, and the cycle purge process as repeating units, the separated porous carbon is surely discharged, and then the first and second cleaning processes are performed. A process can be performed.

(5) In any one of the above (1) to (4), by supplying oxygen gas to the gas exhaust pipe, even if the porous carbon separated in the gas exhaust pipe remains, it can be reliably discharged. it can.

Hereinafter, main aspects of the invention included in the present embodiment will be described below.
(Appendix 1)
A cleaning method for removing a silicon carbide film deposited on a member provided in a reaction chamber, the first step of supplying hydrogen gas with the pressure in the reaction chamber being a first pressure, and after the first step And a second step of supplying the hydrogen gas in a state where the pressure in the reaction chamber is set to a second pressure higher than the first pressure.

  (Supplementary note 2) The cleaning method according to Supplementary note 1, wherein the second step is performed while exhausting the atmosphere in the reaction chamber.

  (Supplementary note 3) The cleaning method according to supplementary note 1 or 2, further comprising a third step of repeating the supply of the hydrogen gas or the inert gas to the reaction chamber and the exhaust of the atmosphere in the reaction chamber after the second step. .

  (Supplementary note 4) The cleaning method according to any one of supplementary notes 1 to 3, wherein the first step and the second step are repeated a plurality of times.

  (Supplementary note 5) The cleaning method according to supplementary note 3, wherein the first step, the second step, and the third step are repeated a plurality of times as one unit.

  (Additional remark 6) The cleaning method which supplies oxygen gas to the gas exhaust pipe which exhausts the atmosphere in the said reaction chamber in Additional remark 1 thru | or 5.

(Appendix 7)
A reaction chamber in which a substrate to be processed on which a silicon carbide film is to be formed is placed; a first member provided in the reaction chamber; and the silicon carbide film formed on the substrate to be processed provided in the reaction chamber. A plurality of gas supply systems for supplying a film forming gas, an exhaust system for exhausting the atmosphere of the reaction chamber, and hydrogen gas from at least one of the plurality of gas supply systems to the reaction chamber and the reaction The plurality of gas supply systems and the exhaust system are controlled so that the pressure of the chamber becomes the first pressure, and then hydrogen gas is supplied from at least one of the plurality of gas supply systems and the reaction chamber A substrate processing apparatus comprising: the plurality of gas supply systems and a controller that controls the exhaust system so that the pressure is a second pressure higher than the first pressure.

  DESCRIPTION OF SYMBOLS 10: Semiconductor manufacturing apparatus, 12: Housing | casing, 14: Wafer, 15: Wafer holder, 15a: Upper wafer holder, 15b: Lower wafer holder, 16: Pod, 18: Pod stage, 20: Pod conveyance apparatus, 22: Pod Storage shelf, 24: Pod opener, 26: Substrate number detector, 28: Substrate transfer machine, 30: Boat, 32: Arm, 34A: Boat heat insulation part, 34B: First heat exchange part, 34C: Second heat exchange Part: 36: manifold, 40: processing furnace, 42: reaction tube, 44: reaction chamber, 48: derivative, 50: induction coil, 52: temperature controller, 54: heat insulating material, 55: outer heat insulating wall, 58: Magnetic seal, 60: first gas supply nozzle, 68: first gas supply port, 70: second gas supply nozzle, 72: second gas supply port 72, 78: gas flow rate controller, 90: first 1 Gas exhaust port, 98: pressure control unit, 150: main control unit, 152: controller, 200: gas supply unit, 210: gas supply source, 211: MFC, 212: valve, 214: APC valve, 222: first Gas line, 230: gas exhaust pipe, 260: second gas line, 300: structure, 360: third gas supply port, 390: second gas exhaust port.

Claims (2)

A cleaning method for removing a silicon carbide film deposited on a member provided in a reaction chamber,
A first step of supplying hydrogen gas with the pressure in the reaction chamber being a first pressure;
And a second step of supplying the hydrogen gas in a state where the pressure in the reaction chamber is set to a second pressure higher than the first pressure after the first step. A reaction chamber in which a substrate to be processed on which a silicon carbide film is formed is placed;
A first member provided in the reaction chamber;
A plurality of gas supply systems that are provided in the reaction chamber and supply a film forming gas for forming the silicon carbide film on the substrate to be processed;
An exhaust system for exhausting the atmosphere of the reaction chamber;
Controlling the plurality of gas supply systems and the exhaust system so that hydrogen gas is supplied to the reaction chamber from at least one of the plurality of gas supply systems and the pressure of the reaction chamber becomes the first pressure; Thereafter, hydrogen gas is supplied from at least one of the plurality of gas supply systems, and the pressure of the reaction chamber is set to a second pressure higher than the first pressure, and the plurality of gas supply systems and the exhaust system A substrate processing apparatus.