JP2019220576A - Heat treatment apparatus and atmosphere replacement method for heat treatment apparatus - Google Patents

Abstract

To provide a heat treatment apparatus capable of completely discharging a reactive gas from a supply pipe for supplying a reactive gas and filling the supply pipe with an inert gas, and an atmosphere replacement method for the heat treatment apparatus.SOLUTION: A reactive gas pipe 83a is continued to be exhausted until a measured value of a supply confirmation pressure gauge 94 becomes equal to or less than a first pressure, and then residual ammonia is completely discharged from the reactive gas pipe 83a regardless of the full scale size of a mass flow controller 95. Further, after discharging the ammonia from the reactive gas pipe 83a, the supply of the nitrogen gas to the reactive gas pipe 83a is continued until the measured value of the supply confirmation pressure gauge 94 becomes equal to or higher than a second pressure higher than the first pressure. Thereby, the reactive gas pipe 83a can be sufficiently supplied with and filled with the nitrogen gas.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat treatment apparatus for heating a thin plate-like precision electronic substrate (hereinafter, simply referred to as a “substrate”) such as a semiconductor wafer by irradiating the substrate with light, and an atmosphere replacement method of the heat treatment apparatus.

  2. Description of the Related Art In a semiconductor device manufacturing process, flash lamp annealing (FLA) for heating a semiconductor wafer in an extremely short time has attracted attention. Flash lamp annealing uses a xenon flash lamp (hereinafter simply referred to as a xenon flash lamp) to irradiate the surface of a semiconductor wafer with flash light, thereby extremely exposing only the surface of the semiconductor wafer. This is a heat treatment technology that raises the temperature in a short time (several milliseconds or less).

  The emission spectral distribution of the xenon flash lamp is from the ultraviolet region to the near infrared region, the wavelength is shorter than that of the conventional halogen lamp, and almost coincides with the basic absorption band of a silicon semiconductor wafer. Therefore, when the semiconductor wafer is irradiated with flash light from the xenon flash lamp, the transmitted light is small and the temperature of the semiconductor wafer can be rapidly raised. In addition, it has been found that when the flash light is irradiated for a very short time of several milliseconds or less, only the vicinity of the surface of the semiconductor wafer can be selectively heated.

  Such flash lamp annealing is used for a process that requires heating for an extremely short time, for example, activation of impurities typically implanted into a semiconductor wafer. By irradiating the surface of the semiconductor wafer into which impurities are implanted by the ion implantation method with flash light from a flash lamp, the surface of the semiconductor wafer can be heated to the activation temperature for a very short time, and the impurities can be diffused deeply. Without activation, only impurity activation can be performed.

  On the other hand, it has been attempted to perform flash lamp annealing in an atmosphere of a reactive gas such as ammonia. For example, in Patent Document 1, an ammonia atmosphere is formed in a chamber containing a semiconductor wafer on which a high dielectric constant gate insulating film (high-k film) is formed, and the semiconductor wafer is irradiated with flash light and heated. It is disclosed that heat treatment is performed after the formation of the high dielectric constant gate insulating film. In the apparatus disclosed in Patent Document 1, after performing a heat treatment of a semiconductor wafer in an ammonia atmosphere, the inside of the chamber is decompressed to discharge harmful ammonia and replaced with a nitrogen atmosphere, and then the semiconductor wafer is unloaded. ing.

JP 2017-045982 A

  Meanwhile, the heat treatment apparatus for performing the flash lamp annealing is regularly or irregularly maintained. At the time of maintenance, since the space in the chamber is opened to the outside, it is necessary to completely discharge harmful reactive gas such as ammonia from the inside of the chamber.

  However, various pipes connected to the chamber may be provided with a mass flow controller or may have a large pipe pressure loss due to various reasons such as a small pipe diameter. In particular, when the pressure loss of a supply pipe for supplying a reactive gas such as ammonia is large, even if ammonia in the chamber can be discharged simply by reducing the pressure in the chamber as disclosed in Patent Literature 1, It is difficult to completely remove ammonia and the like remaining in the supply pipe.

  The present invention has been made in view of the above problems, and a heat treatment apparatus capable of completely discharging a reactive gas from a supply pipe for supplying a reactive gas and filling the supply pipe with an inert gas. An object of the present invention is to provide an atmosphere replacement method for a heat treatment apparatus.

  In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a heat treatment apparatus for heating a substrate by irradiating the substrate with light, wherein a chamber for accommodating the substrate and light are applied to the substrate accommodated in the chamber. A light irradiation unit for irradiation, a first supply pipe for supplying a reactive gas to the chamber, a second supply pipe for supplying an inert gas to the chamber, an exhaust pipe for exhausting an atmosphere in the chamber, A pressure gauge provided in a first supply pipe, and after exhausting the first supply pipe from the exhaust pipe until a measured value of the pressure gauge becomes equal to or less than a first atmospheric pressure, An inert gas is supplied from the second supply pipe to the first supply pipe until the measured value becomes equal to or higher than a second pressure higher than the first pressure.

  According to a second aspect of the present invention, in the heat treatment apparatus according to the first aspect, a mass flow controller is further provided in the first supply pipe.

  Further, according to a third aspect of the present invention, in the heat treatment apparatus according to the first or second aspect of the present invention, the light irradiation unit includes a continuous lighting lamp, and before the exhaust pipe exhausts gas from the continuous lighting lamp. Light irradiation is performed to heat the atmosphere in the chamber.

  According to a fourth aspect of the present invention, in the method for replacing atmosphere in a heat treatment apparatus for heating a substrate by irradiating the substrate with light, a first supply pipe for supplying a reactive gas to a chamber for accommodating the substrate is provided. A second supply pipe for supplying gas and an exhaust pipe for exhausting the atmosphere in the chamber are connected, and a pressure gauge is provided in the first supply pipe, and a measured value of the pressure gauge is equal to or less than a first pressure. An evacuation step of exhausting the first supply pipe from the evacuation pipe until the above, and after the evacuation step, until the measured value of the pressure gauge becomes equal to or higher than a second pressure higher than the first pressure. Supplying an inert gas from a second supply pipe to the first supply pipe.

  According to a fifth aspect of the present invention, in the method for replacing atmosphere in the heat treatment apparatus according to the fourth aspect of the present invention, the exhausting step and the air supply step are repeated.

  According to a sixth aspect of the present invention, in the method for replacing atmosphere of the heat treatment apparatus according to the fourth or fifth aspect of the present invention, the atmosphere in the chamber is irradiated with light from a continuous lighting lamp before the evacuation step. The method further includes a heating step of heating.

  According to the first to third aspects of the present invention, the first supply pipe is evacuated from the exhaust pipe until the measured value of the pressure gauge provided in the first supply pipe becomes equal to or lower than the first atmospheric pressure. Since the inert gas is supplied from the second supply pipe to the first supply pipe until the measured value of the meter becomes equal to or higher than the second pressure higher than the first pressure, regardless of the magnitude of the pressure loss of the first supply pipe. Instead, the reactive gas can be completely discharged from the first supply pipe, and the first supply pipe can be filled with the inert gas.

  In particular, according to the third aspect of the invention, before exhausting from the exhaust pipe, the atmosphere in the chamber is heated by irradiating light from the continuous lighting lamp, so that the thermal motion of gas molecules in the atmosphere is activated, The evacuation time required for the measured value of the pressure gauge to be equal to or lower than the first atmospheric pressure can be reduced.

  According to the fourth to sixth aspects of the present invention, the first supply pipe is evacuated from the exhaust pipe until the measured value of the pressure gauge provided on the first supply pipe becomes equal to or lower than the first atmospheric pressure. Since the inert gas is supplied from the second supply pipe to the first supply pipe until the measured value of the meter becomes equal to or higher than the second pressure higher than the first pressure, regardless of the magnitude of the pressure loss of the first supply pipe. Instead, the reactive gas can be completely discharged from the first supply pipe, and the first supply pipe can be filled with the inert gas.

  In particular, according to the invention of claim 6, since the atmosphere in the chamber is heated by irradiating light from the continuous lighting lamp before the evacuation step, the thermal motion of the gas molecules in the atmosphere is activated, and The evacuation time required until the measured value becomes equal to or lower than the first atmospheric pressure can be reduced.

It is a longitudinal section showing the composition of the heat treatment equipment concerning the present invention. It is a perspective view which shows the whole external appearance of a holding part. It is a top view of a susceptor. It is sectional drawing of a susceptor. It is a top view of a transfer mechanism. It is a side view of a transfer mechanism. It is a top view showing arrangement of a plurality of halogen lamps. It is a flowchart which shows the procedure of the atmosphere replacement method of a heat processing apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a longitudinal sectional view showing a configuration of a heat treatment apparatus 1 according to the present invention. The heat treatment apparatus 1 in FIG. 1 is a flash lamp annealing apparatus that heats a semiconductor wafer W having a disc shape as a substrate by irradiating the semiconductor wafer W with flash light. The size of the semiconductor wafer W to be processed is not particularly limited, but is, for example, φ300 mm or φ450 mm (φ300 mm in the present embodiment). A high dielectric constant film (high-k film) is formed as a gate insulating film on the semiconductor wafer W before being loaded into the heat treatment apparatus 1. (PDA: Post Deposition Anneal) is executed. Note that, in FIG. 1 and each of the following drawings, the dimensions and the numbers of the respective parts are exaggerated or simplified as necessary for easy understanding.

  The heat treatment apparatus 1 includes a chamber 6 containing a semiconductor wafer W, a flash heating unit 5 containing a plurality of flash lamps FL, and a halogen heating unit 4 containing a plurality of halogen lamps HL. A flash heating unit 5 is provided above the chamber 6, and a halogen heating unit 4 is provided below the chamber 6. The heat treatment apparatus 1 further includes a holding unit 7 that holds the semiconductor wafer W in a horizontal position inside the chamber 6, a transfer mechanism 10 that transfers the semiconductor wafer W between the holding unit 7 and the outside of the apparatus, Is provided. Further, the heat treatment apparatus 1 includes a control unit 3 that controls each operation mechanism provided in the halogen heating unit 4, the flash heating unit 5, and the chamber 6 to execute the heat treatment of the semiconductor wafer W.

  The chamber 6 is configured by mounting a quartz chamber window above and below a cylindrical chamber side portion 61. The chamber side portion 61 has a substantially cylindrical shape with an open top and bottom, an upper chamber window 63 is mounted and closed on an upper opening, and a lower chamber window 64 is mounted and closed on a lower opening. ing. The upper chamber window 63 that forms the ceiling of the chamber 6 is a disk-shaped member formed of quartz, and functions as a quartz window that transmits flash light emitted from the flash heating unit 5 into the chamber 6. The lower chamber window 64 constituting the floor of the chamber 6 is also a disc-shaped member formed of quartz, and functions as a quartz window for transmitting light from the halogen heating unit 4 into the chamber 6.

  A reflection ring 68 is mounted on the upper part of the inner wall surface of the chamber side part 61, and a reflection ring 69 is mounted on the lower part. The reflection rings 68 and 69 are both formed in an annular shape. The upper reflecting ring 68 is mounted by being fitted from above the chamber side 61. On the other hand, the lower reflective ring 69 is mounted by being fitted from below the chamber side 61 and fastened with screws (not shown). That is, the reflection rings 68 and 69 are both detachably attached to the chamber side 61. The space inside the chamber 6, that is, the space surrounded by the upper chamber window 63, the lower chamber window 64, the chamber side 61, and the reflection rings 68 and 69 is defined as the heat treatment space 65.

  By attaching the reflection rings 68 and 69 to the chamber side 61, a concave portion 62 is formed on the inner wall surface of the chamber 6. That is, a concave portion 62 is formed which is surrounded by a central portion of the inner wall surface of the chamber side portion 61 where the reflection rings 68 and 69 are not mounted, a lower end surface of the reflection ring 68, and an upper end surface of the reflection ring 69. . The concave portion 62 is formed in an annular shape along the horizontal direction on the inner wall surface of the chamber 6 and surrounds the holding portion 7 that holds the semiconductor wafer W. The chamber side 61 and the reflection rings 68 and 69 are formed of a metal material (for example, stainless steel) having excellent strength and heat resistance.

  Further, a transfer opening (furnace opening) 66 for carrying the semiconductor wafer W into and out of the chamber 6 is formed in the chamber side portion 61. The transport opening 66 can be opened and closed by a gate valve 185. The transport opening 66 is connected to the outer peripheral surface of the recess 62 in communication. For this reason, when the gate valve 185 opens the transfer opening 66, the semiconductor wafer W is loaded into the heat treatment space 65 from the transfer opening 66 through the concave portion 62 and unloaded from the heat treatment space 65. It can be performed. When the gate valve 185 closes the transfer opening 66, the heat treatment space 65 in the chamber 6 becomes a closed space.

  Further, a through hole 61a is formed in the chamber side portion 61. The radiation thermometer 20 is attached to a portion of the outer wall surface of the chamber side portion 61 where the through hole 61a is provided. The through hole 61a is a cylindrical hole for guiding infrared light emitted from the lower surface of the semiconductor wafer W held by a susceptor 74 described later to the radiation thermometer 20. The through hole 61a is provided to be inclined with respect to the horizontal direction so that the axis in the through direction intersects with the main surface of the semiconductor wafer W held by the susceptor 74. At the end of the through hole 61a on the side facing the heat treatment space 65, a transparent window 21 made of a barium fluoride material that transmits infrared light in a wavelength range that can be measured by the radiation thermometer 20 is mounted.

Further, a gas supply hole 81 for supplying a processing gas (in this embodiment, nitrogen gas (N ₂ ) and / or ammonia (NH ₃ )) to the heat treatment space 65 is formed in an upper portion of the inner wall of the chamber 6. The gas supply hole 81 is formed at a position above the concave portion 62, and may be provided on the reflection ring 68. The gas supply hole 81 is connected to a gas supply pipe 83 through a buffer space 82 formed in an annular shape inside the side wall of the chamber 6. The gas supply pipe 83 is branched into two branches, one of which is a reactive gas pipe (first supply pipe) 83a is connected to the ammonia supply source 91, and the other is an inert gas pipe (second supply pipe) 83b. It is connected to a nitrogen supply 92. The ammonia supply source 91 supplies ammonia to the reactive gas pipe 83a under the control of the control unit 3. The nitrogen supply source 92 supplies nitrogen gas to the inert gas pipe 83b under the control of the control unit 3.

  A supply source valve 93, a supply confirmation pressure gauge 94, a mass flow controller 95, and a supply valve 96 are interposed in the middle of the route of the reactive gas pipe 83a. When the supply source valve 93 and the supply valve 96 are opened, ammonia is supplied from the ammonia supply source 91 to the buffer space 82 via the reactive gas pipe 83a and the gas supply pipe 83. The supply confirmation pressure gauge 94 determines whether ammonia is supplied from the ammonia supply source 91 to the reactive gas pipe 83a at a predetermined pressure. The mass flow controller 95 adjusts the flow rate of ammonia flowing through the reactive gas pipe 83a to a predetermined set value.

  On the other hand, a mass flow controller 97 and a supply valve 98 are interposed in the middle of the path of the inert gas pipe 83b. When the supply valve 98 is opened, nitrogen gas is supplied from the nitrogen supply source 92 to the buffer space 82 via the inert gas pipe 83b and the gas supply pipe 83. The mass flow controller 97 adjusts the flow rate of the nitrogen gas flowing through the inert gas pipe 83b to a predetermined set value. When all of the supply source valve 93, the supply valve 96, and the supply valve 98 are open, the ammonia supplied from the reactive gas pipe 83a and the nitrogen gas supplied from the inert gas pipe 83b are connected to the gas supply pipe. At 83, a mixed gas of ammonia and nitrogen gas is supplied to the buffer space 82.

  In addition, a bypass pipe 84 that connects the reactive gas pipe 83a and the inert gas pipe 83b is provided. The bypass pipe 84 communicates a part of the reactive gas pipe 83a between the supply source valve 93 and the supply confirmation pressure gauge 94 and a part of the inert gas pipe 83b between the nitrogen supply source 92 and the mass flow controller 97. Connecting. A bypass valve 85 is inserted into the bypass pipe 84. When the bypass valve 85 is opened, the reactive gas pipe 83a communicates with the inert gas pipe 83b.

  The processing gas supplied from the gas supply pipe 83 and flowing into the buffer space 82 flows so as to expand in the buffer space 82 having a smaller fluid resistance than the gas supply holes 81 and fills the buffer space 82. Then, the processing gas filling the buffer space 82 is supplied from the gas supply holes 81 into the heat treatment space 65.

  A gas exhaust hole 86 for exhausting gas in the heat treatment space 65 is formed in a lower portion of the inner wall of the chamber 6. The gas exhaust hole 86 is formed at a position lower than the concave portion 62, and may be provided on the reflection ring 69. The gas exhaust hole 86 is connected to a gas exhaust pipe 88 via a buffer space 87 formed in an annular shape inside the side wall of the chamber 6. The gas exhaust pipe 88 is connected to the exhaust part 190. An exhaust valve 89 and a vacuum pressure gauge 191 are interposed in the middle of the path of the gas exhaust pipe 88. When the exhaust valve 89 is opened, the gas in the heat treatment space 65 is exhausted from the gas exhaust hole 86 to the gas exhaust pipe 88 via the buffer space 87. The vacuum pressure gauge 191 directly measures the pressure of the gas exhaust pipe 88. Since the pressure at the portion of the gas exhaust pipe 88 where the vacuum pressure gauge 191 is provided is almost the same as the pressure inside the chamber 6, the pressure measured by the vacuum pressure gauge 191 is also the pressure inside the chamber 6. Note that a plurality of gas supply holes 81 and gas exhaust holes 86 may be provided along the circumferential direction of the chamber 6, or may be slit-shaped.

  As the exhaust unit 190, an exhaust utility of a factory where the vacuum pump and the heat treatment apparatus 1 are installed can be used. When a vacuum pump is employed as the exhaust unit 190 and the atmosphere in the heat treatment space 65, which is a closed space, is exhausted without supplying any gas from the gas supply holes 81, the pressure in the chamber 6 can be reduced to a vacuum atmosphere. Further, even when a vacuum pump is not used as the exhaust unit 190, the inside of the chamber 6 can be depressurized to a pressure lower than the atmospheric pressure by performing the exhaust without supplying the gas from the gas supply hole 81. . The reduced pressure in the chamber 6 is measured by the vacuum pressure gauge 191.

  FIG. 2 is a perspective view showing the overall appearance of the holding unit 7. The holding section 7 includes a base ring 71, a connecting section 72, and a susceptor 74. The base ring 71, the connecting portion 72, and the susceptor 74 are all formed of quartz. That is, the entire holding portion 7 is formed of quartz.

  The base ring 71 is an arc-shaped quartz member in which a part is omitted from the ring shape. The missing portion is provided to prevent interference between a transfer arm 11 of the transfer mechanism 10 described below and the base ring 71. The base ring 71 is supported on the wall surface of the chamber 6 by being placed on the bottom surface of the concave portion 62 (see FIG. 1). A plurality of connecting portions 72 (four in this embodiment) are erected on the upper surface of the base ring 71 along the circumferential direction of the ring shape. The connecting portion 72 is also a quartz member, and is fixed to the base ring 71 by welding.

  The susceptor 74 is supported by four connecting portions 72 provided on the base ring 71. FIG. 3 is a plan view of the susceptor 74. FIG. 4 is a sectional view of the susceptor 74. The susceptor 74 includes a holding plate 75, a guide ring 76, and a plurality of substrate support pins 77. The holding plate 75 is a substantially circular plate-shaped member formed of quartz. The diameter of the holding plate 75 is larger than the diameter of the semiconductor wafer W. That is, the holding plate 75 has a larger planar size than the semiconductor wafer W.

  A guide ring 76 is provided on a peripheral edge of the upper surface of the holding plate 75. The guide ring 76 is an annular member having an inner diameter larger than the diameter of the semiconductor wafer W. For example, when the diameter of the semiconductor wafer W is φ300 mm, the inner diameter of the guide ring 76 is φ320 mm. The inner circumference of the guide ring 76 has a tapered surface that widens upward from the holding plate 75. The guide ring 76 is formed of the same quartz as the holding plate 75. The guide ring 76 may be welded to the upper surface of the holding plate 75, or may be fixed to the holding plate 75 by a separately processed pin or the like. Alternatively, the holding plate 75 and the guide ring 76 may be processed as an integral member.

  A region inside the guide ring 76 on the upper surface of the holding plate 75 is a flat holding surface 75a for holding the semiconductor wafer W. A plurality of substrate support pins 77 are erected on the holding surface 75a of the holding plate 75. In the present embodiment, a total of twelve substrate support pins 77 are erected every 30 ° along the circumference of the outer circumference of the holding surface 75a (the inner circumference of the guide ring 76). The diameter of the circle in which the twelve substrate support pins 77 are arranged (the distance between the opposing substrate support pins 77) is smaller than the diameter of the semiconductor wafer W. If the diameter of the semiconductor wafer W is φ300 mm, φ270 mm to φ280 mm (this embodiment) (Φ270 mm in the form). Each substrate support pin 77 is formed of quartz. The plurality of substrate support pins 77 may be provided on the upper surface of the holding plate 75 by welding, or may be processed integrally with the holding plate 75.

  Returning to FIG. 2, the four connecting portions 72 erected on the base ring 71 and the peripheral edge of the holding plate 75 of the susceptor 74 are fixed by welding. That is, the susceptor 74 and the base ring 71 are fixedly connected by the connecting portion 72. By supporting the base ring 71 of the holder 7 on the wall surface of the chamber 6, the holder 7 is mounted on the chamber 6. When the holding unit 7 is mounted on the chamber 6, the holding plate 75 of the susceptor 74 is in a horizontal posture (a posture in which the normal line coincides with the vertical direction). That is, the holding surface 75a of the holding plate 75 is a horizontal plane.

  The semiconductor wafer W carried into the chamber 6 is placed and held in a horizontal posture on the susceptor 74 of the holding unit 7 mounted on the chamber 6. At this time, the semiconductor wafer W is supported by twelve substrate support pins 77 erected on the holding plate 75 and held by the susceptor 74. More precisely, the upper ends of the twelve substrate support pins 77 contact the lower surface of the semiconductor wafer W to support the semiconductor wafer W. Since the height of the twelve substrate support pins 77 (the distance from the upper end of the substrate support pins 77 to the holding surface 75a of the holding plate 75) is uniform, the semiconductor wafer W is placed in a horizontal posture by the twelve substrate support pins 77. Can be supported.

  Further, the semiconductor wafer W is supported by the plurality of substrate support pins 77 at a predetermined distance from the holding surface 75a of the holding plate 75. The thickness of the guide ring 76 is larger than the height of the substrate support pins 77. Therefore, the horizontal displacement of the semiconductor wafer W supported by the plurality of substrate support pins 77 is prevented by the guide ring 76.

  As shown in FIGS. 2 and 3, the holding plate 75 of the susceptor 74 has an opening 78 penetrating vertically. The opening 78 is provided for the radiation thermometer 20 to receive radiation light (infrared light) radiated from the lower surface of the semiconductor wafer W. That is, the radiation thermometer 20 receives light radiated from the lower surface of the semiconductor wafer W through the opening 78 and the transparent window 21 attached to the through hole 61a of the chamber side portion 61, and reduces the temperature of the semiconductor wafer W. Measure. Further, the holding plate 75 of the susceptor 74 is provided with four through holes 79 through which the lift pins 12 of the transfer mechanism 10, which will be described later, pass through for transferring the semiconductor wafer W.

  FIG. 5 is a plan view of the transfer mechanism 10. FIG. 6 is a side view of the transfer mechanism 10. The transfer mechanism 10 includes two transfer arms 11. The transfer arm 11 is formed in a circular arc shape along the generally annular concave portion 62. Each transfer arm 11 is provided with two lift pins 12 standing upright. The transfer arm 11 and the lift pins 12 are formed of quartz. Each transfer arm 11 is rotatable by a horizontal moving mechanism 13. The horizontal moving mechanism 13 moves the pair of transfer arms 11 to a transfer operation position (solid line position in FIG. 5) where the semiconductor wafer W is transferred to the holding unit 7 and the semiconductor wafer W held by the holding unit 7. The horizontal movement is performed between a retracted position (a position indicated by a two-dot chain line in FIG. 5) that does not overlap in a plan view. The horizontal moving mechanism 13 may be configured to rotate each transfer arm 11 by an individual motor, or may be rotated by a single motor using a link mechanism to link a pair of transfer arms 11. It may be moved.

  Further, the pair of transfer arms 11 is moved up and down by the elevating mechanism 14 together with the horizontal moving mechanism 13. When the lifting mechanism 14 raises the pair of transfer arms 11 at the transfer operation position, a total of four lift pins 12 pass through the through holes 79 (see FIGS. 2 and 3) formed in the susceptor 74, and The upper end of 12 protrudes from the upper surface of susceptor 74. On the other hand, when the elevating mechanism 14 lowers the pair of transfer arms 11 at the transfer operation position, pulls out the lift pins 12 from the through holes 79, and moves the horizontal transfer mechanism 13 to open the pair of transfer arms 11, The transfer arm 11 moves to the retreat position. The retracted position of the pair of transfer arms 11 is immediately above the base ring 71 of the holding unit 7. Since the base ring 71 is placed on the bottom surface of the concave portion 62, the retreat position of the transfer arm 11 is inside the concave portion 62. It should be noted that an exhaust mechanism (not shown) is also provided near the portion where the driving section (the horizontal moving mechanism 13 and the elevating mechanism 14) of the transfer mechanism 10 is provided. Is discharged to the outside of the chamber 6.

  Returning to FIG. 1, the flash heating unit 5 provided above the chamber 6 includes a light source composed of a plurality of (30 in this embodiment) xenon flash lamps FL and a light source above the light source. And a reflector 52 provided so as to cover. Further, a lamp light emission window 53 is mounted on the bottom of the housing 51 of the flash heating unit 5. The lamp light emission window 53 constituting the floor of the flash heating unit 5 is a plate-shaped quartz window formed of quartz. When the flash heating unit 5 is installed above the chamber 6, the lamp light emission window 53 faces the upper chamber window 63. The flash lamp FL irradiates the heat treatment space 65 with flash light from above the chamber 6 through the lamp light emission window 53 and the upper chamber window 63.

  Each of the plurality of flash lamps FL is a rod-shaped lamp having a long cylindrical shape, and has a longitudinal direction along the main surface of the semiconductor wafer W held by the holding unit 7 (that is, along the horizontal direction). They are arranged in a plane so as to be parallel to each other. Therefore, the plane formed by the arrangement of the flash lamps FL is also a horizontal plane. The area where the plurality of flash lamps FL are arranged is larger than the plane size of the semiconductor wafer W.

  The xenon flash lamp FL has a rod-shaped glass tube (discharge tube) in which xenon gas is sealed and an anode and a cathode connected to a condenser are disposed at both ends thereof, and is provided on the outer peripheral surface of the glass tube. And a trigger electrode. Since xenon gas is electrically an insulator, electricity does not flow in a glass tube in a normal state even if charges are stored in a capacitor. However, when a high voltage is applied to the trigger electrode to break the insulation, the electricity stored in the capacitor flows instantaneously into the glass tube, and light is emitted by excitation of xenon atoms or molecules at that time. In such a xenon flash lamp FL, electrostatic energy previously stored in a condenser is converted into an extremely short light pulse of 0.1 to 100 milliseconds. It has a feature that it can emit extremely strong light compared to a light source. That is, the flash lamp FL is a pulsed lamp that emits light instantaneously in a very short time of less than one second. The light emission time of the flash lamp FL can be adjusted by the coil constant of a lamp power supply that supplies power to the flash lamp FL.

  The reflector 52 is provided above the plurality of flash lamps FL so as to entirely cover the flash lamps FL. The basic function of the reflector 52 is to reflect flash light emitted from the plurality of flash lamps FL to the heat treatment space 65 side. The reflector 52 is made of an aluminum alloy plate, and its surface (the surface facing the flash lamp FL) is roughened by blasting.

  The halogen heater 4 provided below the chamber 6 has a plurality of (40 in this embodiment) halogen lamps HL inside the housing 41. The halogen heater 4 is a light irradiator that heats the semiconductor wafer W by irradiating the heat treatment space 65 from below the chamber 6 through the lower chamber window 64 with a plurality of halogen lamps HL.

  FIG. 7 is a plan view showing an arrangement of a plurality of halogen lamps HL. The forty halogen lamps HL are arranged in two upper and lower stages. Twenty halogen lamps HL are arranged in an upper stage near the holding unit 7 and 20 halogen lamps HL are arranged in a lower stage farther from the holding unit 7 than the upper stage. Each of the halogen lamps HL is a rod-shaped lamp having a long cylindrical shape. The 20 halogen lamps HL in the upper and lower rows are arranged so that their respective longitudinal directions are parallel to each other along the main surface of the semiconductor wafer W held by the holding section 7 (that is, along the horizontal direction). I have. Therefore, the plane formed by the arrangement of the halogen lamps HL in both the upper and lower stages is a horizontal plane.

  Further, as shown in FIG. 7, the arrangement density of the halogen lamps HL is higher in a region facing the peripheral portion than in a region facing the center of the semiconductor wafer W held by the holding portion 7 in both the upper stage and the lower stage. I have. That is, in both upper and lower stages, the arrangement pitch of the halogen lamps HL is shorter at the periphery than at the center of the lamp array. For this reason, it is possible to irradiate a larger amount of light to the peripheral portion of the semiconductor wafer W where the temperature is likely to decrease during heating by light irradiation from the halogen heating unit 4.

  Further, a lamp group composed of the upper halogen lamps HL and a lamp group composed of the lower halogen lamps HL are arranged so as to intersect in a grid pattern. That is, a total of 40 halogen lamps HL are arranged such that the longitudinal direction of the 20 halogen lamps HL arranged in the upper stage and the longitudinal direction of the 20 halogen lamps HL arranged in the lower stage are orthogonal to each other. I have.

  The halogen lamp HL is a filament type light source that emits light by incandescent the filament by energizing the filament disposed inside the glass tube. A gas in which a trace amount of a halogen element (iodine, bromine, or the like) is introduced into an inert gas such as nitrogen or argon is sealed inside the glass tube. By introducing a halogen element, it is possible to set the temperature of the filament to a high temperature while suppressing breakage of the filament. Therefore, the halogen lamp HL has a characteristic that it has a longer life and can continuously emit strong light as compared with a normal incandescent lamp. That is, the halogen lamp HL is a continuous lighting lamp that continuously emits light for at least one second. Further, since the halogen lamp HL is a rod-shaped lamp, it has a long life, and by arranging the halogen lamp HL along the horizontal direction, the radiation efficiency to the upper semiconductor wafer W becomes excellent.

  A reflector 43 is also provided below the two-stage halogen lamp HL in the housing 41 of the halogen heating unit 4 (FIG. 1). The reflector 43 reflects light emitted from the plurality of halogen lamps HL to the heat treatment space 65 side.

  The control unit 3 controls the above-described various operation mechanisms provided in the heat treatment apparatus 1. The configuration of the control unit 3 as hardware is the same as that of a general computer. That is, the control unit 3 includes a CPU which is a circuit for performing various arithmetic processing, a ROM which is a read-only memory for storing a basic program, a RAM which is a readable and writable memory for storing various information, and control software and data. It has a magnetic disk for storing. The processing in the heat treatment apparatus 1 proceeds when the CPU of the control unit 3 executes a predetermined processing program.

  In addition to the above-described configuration, the heat treatment apparatus 1 prevents an excessive rise in temperature of the halogen heating unit 4, the flash heating unit 5, and the chamber 6 due to heat energy generated from the halogen lamp HL and the flash lamp FL during the heat treatment of the semiconductor wafer W. Therefore, it has various cooling structures. For example, a water cooling tube (not shown) is provided on the wall of the chamber 6. Further, the halogen heating unit 4 and the flash heating unit 5 have an air cooling structure for forming a gas flow therein and discharging heat. Air is also supplied to the gap between the upper chamber window 63 and the lamp light emission window 53 to cool the flash heating unit 5 and the upper chamber window 63.

  Next, a processing operation in the heat treatment apparatus 1 will be described. First, the procedure of the heat treatment for the semiconductor wafer W to be processed will be described. Here, the semiconductor wafer W to be processed is a silicon semiconductor substrate on which a high dielectric constant film is formed as a gate insulating film. The high dielectric constant film is deposited and formed on the surface of the semiconductor wafer W by a technique such as ALD (Atomic Layer Deposition) or MOCVD (Metal Organic Chemical Vapor Deposition). The heat treatment apparatus 1 irradiates the semiconductor wafer W with flash light in an ammonia atmosphere to perform heat treatment after film formation (PDA), thereby eliminating defects in the high dielectric constant film after film formation. The processing procedure of the heat treatment apparatus 1 described below proceeds by the control unit 3 controlling each operation mechanism of the heat treatment apparatus 1.

  First, the semiconductor wafer W on which the high dielectric constant film is formed is carried into the chamber 6 of the heat treatment apparatus 1. When the semiconductor wafer W is loaded, the gate valve 185 is opened to open the transfer opening 66, and the semiconductor wafer W on which the high-dielectric-constant film is formed through the transfer opening 66 is transferred by the transfer robot outside the apparatus into the chamber 6. It is carried into the heat treatment space 65. At this time, since the inside and outside of the chamber 6 are both at atmospheric pressure, the outside atmosphere of the apparatus is drawn into the heat treatment space 65 in the chamber 6 when the semiconductor wafer W is loaded. Therefore, by opening the supply valve 98 and continuing to supply the nitrogen gas from the nitrogen supply source 92 into the chamber 6, the nitrogen gas flow flows out from the transfer opening 66, and the atmosphere outside the apparatus flows into the chamber 6. May be suppressed to a minimum. Further, when the gate valve 185 is opened, it is preferable that the exhaust valve 89 be closed to stop the exhaust from the chamber 6. Thus, the nitrogen gas supplied into the chamber 6 flows out only from the transfer opening 66, so that the inflow of the external atmosphere can be more effectively prevented.

  The semiconductor wafer W carried in by the transfer robot advances to a position immediately above the holding unit 7 and stops. Then, the pair of transfer arms 11 of the transfer mechanism 10 move horizontally from the retracted position to the transfer operation position and rise, so that the lift pins 12 protrude from the upper surface of the holding plate 75 of the susceptor 74 through the through holes 79. To receive the semiconductor wafer W. At this time, the lift pins 12 rise above the upper ends of the substrate support pins 77.

  After the semiconductor wafer W is placed on the lift pins 12, the transfer robot exits the heat treatment space 65, and the transfer opening 66 is closed by the gate valve 185. When the pair of transfer arms 11 is lowered, the semiconductor wafer W is transferred from the transfer mechanism 10 to the susceptor 74 of the holding unit 7 and is held from below in a horizontal posture. The semiconductor wafer W is supported by a plurality of substrate support pins 77 erected on a holding plate 75 and held by a susceptor 74. The semiconductor wafer W is held by the susceptor 74 with the surface on which the high dielectric constant film is formed as the upper surface. A predetermined gap is formed between the back surface (the main surface opposite to the front surface) of the semiconductor wafer W supported by the plurality of substrate support pins 77 and the holding surface 75a of the holding plate 75. The pair of transfer arms 11 that have descended to below the susceptor 74 are retracted by the horizontal moving mechanism 13 to the retracted position, that is, to the inside of the recess 62.

  After the semiconductor wafer W is stored in the chamber 6 and the transfer opening 66 is closed by the gate valve 185, the pressure in the chamber 6 is reduced to a pressure lower than the atmospheric pressure. Specifically, by closing the transfer opening 66, the heat treatment space 65 in the chamber 6 becomes a closed space. In this state, the exhaust valve 89 is opened while the supply valve 96 and the supply valve 98 for supplying air are closed. As a result, the inside of the chamber 6 is evacuated without supplying gas, and the heat treatment space 65 in the chamber 6 is depressurized.

  After the pressure in the chamber 6 is reduced to a predetermined pressure, the supply valve 93, the supply valve 96, and the supply valve 98 are opened while the exhaust valve 89 is opened. When the supply valve 93 and the supply valve 96 are opened, ammonia is supplied from the reactive gas pipe 83a. When the supply valve 98 is opened, the nitrogen gas is supplied from the inert gas pipe 83b. The fed ammonia and the nitrogen gas join at the gas supply pipe 83. Then, a mixed gas of ammonia and nitrogen gas is supplied to the heat treatment space 65 in the chamber 6. As a result, an ammonia atmosphere is formed under reduced pressure around the semiconductor wafer W held by the holding unit 7 in the chamber 6. The concentration of ammonia in the ammonia atmosphere (that is, the mixing ratio of ammonia and nitrogen gas) is not particularly limited and may be an appropriate value, but may be, for example, 10 vol.% Or less (this embodiment). 2.5 vol.% In form). The concentration of ammonia can be adjusted by controlling the supply flow rates of ammonia and nitrogen gas by the mass flow controller 95 and the mass flow controller 97, respectively.

  Next, the 40 halogen lamps HL of the halogen heating unit 4 are simultaneously turned on, and the preliminary heating (assist heating) of the semiconductor wafer W is started. The halogen light emitted from the halogen lamp HL passes through the lower chamber window 64 and the susceptor 74 formed of quartz, and irradiates the lower surface of the semiconductor wafer W. Upon receiving light irradiation from the halogen lamp HL, the semiconductor wafer W is preheated and the temperature rises. Since the transfer arm 11 of the transfer mechanism 10 is retracted inside the concave portion 62, it does not hinder the heating by the halogen lamp HL.

  When performing the preliminary heating by the halogen lamp HL, the temperature of the semiconductor wafer W is measured by the radiation thermometer 20. That is, the radiation thermometer 20 receives infrared light radiated from the lower surface of the semiconductor wafer W held by the susceptor 74 through the opening 78 through the transparent window 21 and measures the temperature of the wafer being heated. The measured temperature of the semiconductor wafer W is transmitted to the control unit 3. The control unit 3 controls the output of the halogen lamp HL while monitoring whether or not the temperature of the semiconductor wafer W heated by the irradiation of light from the halogen lamp HL has reached a predetermined preheating temperature T1. That is, the control unit 3 performs feedback control of the output of the halogen lamp HL based on the value measured by the radiation thermometer 20 so that the temperature of the semiconductor wafer W becomes the preheating temperature T1. The preheating temperature T1 is 300 ° C. or more and 600 ° C. or less, and is 450 ° C. in the present embodiment.

  After the temperature of the semiconductor wafer W reaches the preheating temperature T1, the control unit 3 temporarily maintains the semiconductor wafer W at the preheating temperature T1. Specifically, when the temperature of the semiconductor wafer W measured by the radiation thermometer 20 reaches the preheating temperature T1, the control unit 3 adjusts the output of the halogen lamp HL to substantially reduce the temperature of the semiconductor wafer W to the preheating temperature. The heating temperature T1 is maintained.

  By performing such preheating by the halogen lamp HL, the entire semiconductor wafer W is uniformly heated to the preheating temperature T1. At the stage of preheating by the halogen lamp HL, the temperature of the peripheral portion of the semiconductor wafer W where heat radiation is more likely to occur tends to be lower than that of the central portion, but the arrangement density of the halogen lamp HL in the halogen heating portion 4 is: The region facing the peripheral portion is higher than the region facing the center of the substrate W. Therefore, the amount of light applied to the peripheral portion of the semiconductor wafer W where heat is likely to be generated increases, and the in-plane temperature distribution of the semiconductor wafer W in the preheating stage can be made uniform.

  When a predetermined time elapses after the temperature of the semiconductor wafer W reaches the preheating temperature T1, the flash lamp FL of the flash heating unit 5 irradiates the surface of the semiconductor wafer W held by the susceptor 74 with flash light. At this time, a part of the flash light radiated from the flash lamp FL goes directly into the chamber 6, and another part is once reflected by the reflector 52 and then goes into the chamber 6. The flash heating of the semiconductor wafer W is performed by the irradiation.

  Since the flash heating is performed by irradiating flash light (flash light) from the flash lamp FL, the surface temperature of the semiconductor wafer W can be increased in a short time. That is, the flash light emitted from the flash lamp FL is converted into a light pulse in which the electrostatic energy previously stored in the condenser is extremely short, and the irradiation time is extremely short, from about 0.1 millisecond to about 100 milliseconds. It is a strong flash. Then, by irradiating the surface of the semiconductor wafer W on which the high dielectric constant film is formed with flash light from the flash lamp FL, the surface of the semiconductor wafer W including the high dielectric constant film instantaneously rises to the processing temperature T2. After the film is heated, a heat treatment is performed. The processing temperature T2, which is the maximum temperature (peak temperature) at which the surface of the semiconductor wafer W reaches by flash light irradiation, is 600 ° C. or more and 1200 ° C. or less, and is 1000 ° C. in the present embodiment.

  When the surface of the semiconductor wafer W is heated to a processing temperature T2 in an ammonia atmosphere and a heat treatment is performed after the film formation, nitridation of the high dielectric constant film is promoted, and the heat treatment is performed in the high dielectric constant film. Defects such as point defects disappear. Since the irradiation time from the flash lamp FL is as short as about 0.1 millisecond to about 100 millisecond, the surface temperature of the semiconductor wafer W may increase from the preheating temperature T1 to the processing temperature T2. The time required is very short, less than one second. The surface temperature of the semiconductor wafer W after the irradiation of the flash light immediately drops rapidly from the processing temperature T2.

  After the completion of the flash heating process, the supply valve 96 and the supply valve 98 are closed, and the pressure in the chamber 6 is reduced again. Thereby, harmful ammonia can be discharged from the heat treatment space 65 in the chamber 6. Subsequently, the exhaust valve 89 is closed and the supply valve 98 is opened, and nitrogen gas is supplied from the nitrogen supply source 92 into the chamber 6 to return to normal pressure (atmospheric pressure). Thereby, the inside of the chamber 6 is replaced with a nitrogen atmosphere. Further, the halogen lamp HL is also turned off, whereby the temperature of the semiconductor wafer W drops from the preheating temperature T1. The temperature of the semiconductor wafer W during the temperature decrease is measured by the radiation thermometer 20, and the measurement result is transmitted to the control unit 3. The control unit 3 monitors whether the temperature of the semiconductor wafer W has dropped to a predetermined temperature based on the measurement result. Then, after the temperature of the semiconductor wafer W falls to a predetermined temperature or less, the pair of transfer arms 11 of the transfer mechanism 10 move horizontally again from the retreat position to the transfer operation position and rise, so that the lift pins 12 The semiconductor wafer W protruding from the upper surface of the semiconductor wafer 74 and having undergone the heat treatment is received from the susceptor 74. Subsequently, the transfer opening 66 closed by the gate valve 185 is opened, and the semiconductor wafer W placed on the lift pins 12 is carried out by a transfer robot outside the apparatus, and the semiconductor wafer W is heated in the heat treatment apparatus 1. Is completed.

  Meanwhile, maintenance is performed on the heat treatment apparatus 1 periodically or irregularly. The maintenance is performed irregularly when some trouble occurs in the heat treatment apparatus 1. When performing the maintenance of the heat treatment apparatus 1, the inside of the chamber 6 is opened and various pipes are removed. Therefore, it is necessary to completely discharge harmful ammonia from the entire heat treatment apparatus 1 including the heat treatment space 65 in the chamber 6 and various pipes before maintenance.

  However, it is sometimes difficult to completely exhaust the ammonia remaining in the reactive gas pipe 83a simply by opening the exhaust valve 89 and exhausting the atmosphere in the chamber 6. The ease with which ammonia can be discharged from the reactive gas pipe 83a largely depends on the mass flow controller 95. The reactive gas pipe 83a is provided with a mass flow controller 95 of various full scale sizes according to the purpose of the process. For example, when a large ammonia supply diversion is required, a mass flow controller 95 having a large full scale size (for example, 100 l / min) is provided in the reactive gas pipe 83a. On the other hand, when high-precision ammonia supply flow rate control is required, a mass flow controller 95 having a relatively small full-scale size (for example, 20 liters / minute) is provided in the reactive gas pipe 83a.

  The mass flow controller 95 having a smaller full scale size has a larger pressure loss than the mass flow controller 95 having a larger full scale size. Therefore, when the small-scale mass flow controller 95 is provided in the reactive gas pipe 83a, it becomes difficult to exhaust the gas from the reactive gas pipe 83a, and it becomes difficult to discharge the ammonia remaining in the pipe. Thus, in the present embodiment, ammonia is completely discharged from the reactive gas pipe 83a regardless of the full scale size of the mass flow controller 95 as described below. Note that since the chamber 6 is not opened during the process of the semiconductor wafer W described above, there is a problem even if a slight amount of ammonia remains in the reactive gas pipe 83a when the chamber 6 is evacuated. Does not.

  FIG. 8 is a flowchart illustrating a procedure of the atmosphere replacement method of the heat treatment apparatus 1. First, the halogen lamp HL is turned on in a state where the semiconductor wafer W does not exist in the chamber 6 before the maintenance is performed (Step S1). The atmosphere in the chamber 6 is heated by the irradiation of light from the halogen lamp HL to increase the temperature, and the thermal motion of the gas molecules in the atmosphere is activated. Although the heating temperature of the atmosphere in step S1 is not particularly limited, the atmosphere in the chamber 6 is heated to about 300 ° C. by, for example, irradiating light from the halogen lamp HL for about 30 minutes.

  After the atmosphere in the chamber 6 is heated, the reactive gas pipe 83a is evacuated (step S2). When performing the exhaust in step S2, the supply source valve 93, the bypass valve 85, and the supply valve 98 are closed, and the supply valve 96 and the exhaust valve 89 are opened. As a result, the gas exhaust pipe 88 exhausts the inside of the chamber 6 and the reactive gas pipe 83a including the mass flow controller 95 (accurately, a portion downstream of the supply valve 93), and the inside of the reactive gas pipe 83a is exhausted. Is decompressed. However, as described above, when the full scale size of the mass flow controller 95 provided in the reactive gas pipe 83a is small, it becomes difficult to exhaust the gas from the reactive gas pipe 83a, and ammonia tends to remain.

  For this reason, in the present embodiment, the evacuation is continued until the measured value of the supply confirmation pressure gauge 94 becomes equal to or lower than the preset first pressure (step S3). Specifically, for example, atmospheric pressure -90 kPa is set as the first pressure in the supply confirmation pressure gauge 94, and the supply confirmation pressure gauge 94 transmits an abnormal signal when the measured value becomes equal to or less than the first pressure.

  When the measured value of the supply confirmation pressure gauge 94 becomes equal to or less than the first pressure and the supply confirmation pressure gauge 94 transmits an abnormal signal, the process proceeds to step S4, in which the exhaust is stopped and the nitrogen gas is supplied to the reactive gas pipe 83a. . At this time, the supply source valve 93, the supply valve 96, and the supply valve 98 are closed, and the bypass valve 85 is opened. As a result, the nitrogen gas supplied from the nitrogen supply source 92 passes through the bypass pipe 84, and the reactive gas pipe 83a including the mass flow controller 95 (more precisely, a portion between the supply source valve 93 and the supply valve 96). Will be filled. Note that the exhaust valve 89 is continuously opened even while the nitrogen gas is being supplied to the reactive gas pipe 83a, and the pressure in the chamber 6 is reduced.

  In the present embodiment, the supply of the nitrogen gas to the reactive gas pipe 83a is continued until the measured value of the supply confirmation pressure gauge 94 becomes equal to or higher than the second pressure set in advance (Step S5). The second pressure is higher than the first pressure. Specifically, for example, 170 kPa is set as the second pressure in the supply confirmation pressure gauge 94, and the supply confirmation pressure gauge 94 transmits a normal signal when the measured value becomes equal to or higher than the second pressure.

  When the measured value of the supply confirmation pressure gauge 94 becomes equal to or higher than the second pressure and the supply confirmation pressure gauge 94 transmits a normal signal, the process proceeds to step S6, and the control unit determines whether the above-described exhaust and nitrogen gas supply have been repeated a set number of times. 3 is determined. In the control unit 3, the set number of repetitions is set in advance using, for example, a GUI (Graphical User Interface). If the exhaust and the supply of the nitrogen gas have not been repeated the set number of times, steps S2 to S5 are repeated again. For example, when “10” is set as the set number of repetitions, the above-described exhaust and nitrogen gas supply are repeated ten times.

  In the present embodiment, the evacuation of the reactive gas pipe 83a is continued until the measured value of the supply confirmation pressure gauge 94 becomes equal to or less than the first pressure. When the full-scale size of the mass flow controller 95 is small, it may be difficult to exhaust the gas from the reactive gas pipe 83a. However, the reactive gas pipe 83a may be used until the measured value of the supply confirmation pressure gauge 94 becomes equal to or less than the first pressure. Irrespective of the full-scale size of the mass flow controller 95, the pressure of the reactive gas pipe 83a can be reduced to the first pressure or less, and the residual ammonia can be completely discharged from the reactive gas pipe 83a. .

  After the ammonia is discharged from the reactive gas pipe 83a, the supply of nitrogen gas to the reactive gas pipe 83a is continued until the measured value of the supply confirmation pressure gauge 94 becomes equal to or higher than the second pressure. When the full-scale size of the mass flow controller 95 is small, it is difficult to supply air to the reactive gas pipe 83a. However, it is difficult to supply the reactive gas to the reactive gas pipe 83a until the measured value of the supply confirmation pressure gauge 94 becomes equal to or higher than the second pressure. By continuing the supply of the nitrogen gas, the reactive gas pipe 83a can be sufficiently supplied with the nitrogen gas and filled therein regardless of the full scale size of the mass flow controller 95.

  As described above, by supplying nitrogen gas following the above-described exhaustion, it is possible to completely discharge ammonia from the reactive gas pipe 83a that supplies ammonia and fill the reactive gas pipe 83a with nitrogen gas. It is. As a result, even if the inside of the chamber 6 is opened at the time of maintenance, there is no possibility that a small amount of ammonia remaining in the reactive gas pipe 83a leaks. Further, by repeating the exhaust from the reactive gas pipe 83a and the supply of the nitrogen gas to the reactive gas pipe 83a a plurality of times, the ammonia is more reliably discharged from the reactive gas pipe 83a and the reactive gas pipe 83a is discharged. 83a can be filled with nitrogen gas.

  The supply confirmation pressure gauge 94 for determining the stop of the exhaust and the stop of the supply of the nitrogen gas is an element that originally determines whether or not ammonia is supplied from the ammonia supply source 91 at an appropriate pressure. That is, according to the present embodiment, it is possible to completely discharge ammonia from the reactive gas pipe 83a and fill the reactive gas pipe 83a with nitrogen gas without newly providing a special mechanism. is there. In addition, the supply / exhaust control can be easily performed because the evacuation may be stopped when the supply confirmation pressure gauge 94 sends an abnormal signal, and the nitrogen gas supply may be stopped when the supply confirmation pressure gauge 94 sends a normal signal.

  Further, in the present embodiment, before exhausting, the atmosphere in the chamber 6 is heated by irradiating light from the halogen lamp HL. Thereby, the thermal motion of the gas molecules in the atmosphere in the chamber 6 is activated, and the gas molecules are quickly exhausted in the subsequent evacuation process. As a result, the evacuation time required until the measured value of the supply confirmation pressure gauge 94 becomes equal to or less than the first pressure can be reduced.

  Although the embodiments of the present invention have been described above, various changes other than those described above can be made in the present invention without departing from the gist thereof. For example, in the above step S3, the evacuation was continued until the measured value of the supply confirmation pressure gauge 94 became equal to or less than the first pressure set in advance. The evacuation may be continued until the value becomes equal to or less than a value (for example, 0.1 kPa). However, when the full-scale size of the mass flow controller 95 is small and it is difficult to exhaust the gas from the reactive gas pipe 83a, the vacuum pressure is already set at the time when the measured value of the supply confirmation pressure gauge 94 becomes equal to or less than the preset first pressure. The measured value of the total 191 is often equal to or less than a predetermined value.

Further, in the above embodiment, ammonia was supplied from the reactive gas pipe 83a. However, the present invention is not limited to this. Oxygen (O ₂ ), hydrogen (H ₂ ), chlorine (Cl ₂ ), hydrogen chloride (HCl), ozone (O ₃ ), nitric oxide (NO), nitrous oxide (N ₂ O), nitrogen dioxide (NO ₂ ), nitrogen trifluoride (NF ₃ ), etc. It may be supplied as a reactive gas. Also, the gas supplied from the inert gas pipe 83b is not limited to nitrogen gas, and argon (Ar), helium (He), or the like may be supplied from the inert gas pipe 83b as an inert gas. good. Even when these various gases are used, by applying the technology according to the present invention, the reactive gas is completely discharged from the reactive gas pipe 83a and the inert gas is introduced into the reactive gas pipe 83a. Can be filled.

  Further, the technology according to the present invention is not limited to the case where the full-scale size of the mass flow controller 95 is small, and can be suitably applied to, for example, a case where the reactive gas piping 83a has a small piping diameter and a large pressure loss. is there.

  Further, in the above-described embodiment, the flash heating unit 5 is provided with 30 flash lamps FL. However, the present invention is not limited to this, and the number of flash lamps FL can be any number. . The flash lamp FL is not limited to a xenon flash lamp, but may be a krypton flash lamp. Further, the number of halogen lamps HL provided in the halogen heating unit 4 is not limited to 40 but may be any number.

  Further, in the above-described embodiment, the preheating of the semiconductor wafer W is performed using the filament type halogen lamp HL as a continuous lighting lamp that emits light continuously for 1 second or more. However, the present invention is not limited to this. The preliminary heating may be performed using a discharge type arc lamp (for example, a xenon arc lamp) as a continuous lighting lamp instead of the halogen lamp HL. In this case, the atmosphere in the chamber 6 is heated by the light irradiation from the arc lamp before the evacuation.

  The substrate to be processed by the heat treatment apparatus 1 is not limited to a semiconductor wafer, but may be a glass substrate used for a flat panel display such as a liquid crystal display device or a substrate for a solar cell. In the heat treatment apparatus 1, activation of the implanted impurities, bonding of metal and silicon, or crystallization of polysilicon may be performed.

REFERENCE SIGNS LIST 1 heat treatment apparatus 3 control unit 4 halogen heating unit 5 flash heating unit 6 chamber 7 holding unit 10 transfer mechanism 65 heat treatment space 74 susceptor 75 holding plate 77 substrate support pin 83 gas supply pipe 83a reactive gas pipe 83b inert gas pipe 84 Bypass piping 85 Bypass valve 88 Gas exhaust pipe 89 Exhaust valve 91 Ammonia supply source 92 Nitrogen supply source 93 Supply source valve 94 Supply confirmation pressure gauge 95,97 Mass flow controller 96,98 Supply valve 190 Exhaust section 191 Vacuum pressure gauge FL Flash lamp HL Halogen lamp W Semiconductor wafer

Claims (6)

A heat treatment apparatus that heats the substrate by irradiating the substrate with light,
A chamber for accommodating the substrate;
A light irradiating unit that irradiates light to the substrate housed in the chamber,
A first supply pipe for supplying a reactive gas to the chamber;
A second supply pipe for supplying an inert gas to the chamber;
An exhaust pipe for exhausting an atmosphere in the chamber,
A pressure gauge provided in the first supply pipe;
With
After evacuating the first supply pipe from the exhaust pipe until the measured value of the pressure gauge becomes equal to or lower than the first pressure, the second pressure is higher than the first pressure by the measured value of the pressure gauge. A heat treatment apparatus, wherein an inert gas is supplied from the second supply pipe to the first supply pipe until the above is achieved. The heat treatment apparatus according to claim 1,
The heat treatment apparatus according to claim 1, wherein a mass flow controller is further provided in the first supply pipe. The heat treatment apparatus according to claim 1 or 2,
The light irradiation unit includes a continuous lighting lamp,
A heat treatment apparatus, wherein the atmosphere in the chamber is heated by irradiating light from the continuous lighting lamp before exhausting from the exhaust pipe. An atmosphere replacement method for a heat treatment apparatus that heats the substrate by irradiating the substrate with light,
A first supply pipe for supplying a reactive gas, a second supply pipe for supplying an inert gas, and an exhaust pipe for exhausting an atmosphere in the chamber are connected to the chamber containing the substrate,
A pressure gauge is provided in the first supply pipe,
An exhausting step of exhausting the first supply pipe from the exhaust pipe until a measurement value of the pressure gauge becomes equal to or less than a first atmospheric pressure;
After the evacuation step, an air supply step of supplying an inert gas from the second supply pipe to the first supply pipe until a measurement value of the pressure gauge becomes equal to or higher than a second pressure higher than the first pressure. When,
An atmosphere replacement method for a heat treatment apparatus, comprising: The atmosphere replacement method for a heat treatment apparatus according to claim 4,
An atmosphere replacement method for a heat treatment apparatus, wherein the exhaust step and the air supply step are repeated. An atmosphere replacement method for a heat treatment apparatus according to claim 4 or claim 5,
An atmosphere replacement method for a heat treatment apparatus, further comprising a heating step of irradiating light from a continuous lighting lamp to heat an atmosphere in the chamber before the evacuation step.

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