Heat treatment method

Abstract

The invention provides a heat treatment method capable of reducing the pressure in a chamber in a short time. A semiconductor wafer (W) is heated by irradiation with light from a halogen lamp (HL) and a flash lamp (FL) in an ammonia atmosphere formed in a chamber (6). When an ammonia gas atmosphere is formed in the chamber (6), the pressure in the chamber (6) is temporarily reduced. In addition, the pressure in the chamber (6) is reduced after the heat treatment of the semiconductor wafer (W). Before the pressure in the chamber (6) is reduced by exhausting the gas, the atmosphere in the chamber (6) is heated by irradiating light from the halogen lamp (HL). By heating the atmosphere within the chamber (6) prior to pressure reduction, the thermal movement of the gas molecules in the atmosphere is activated and the gas density is reduced. As a result, gas molecules in the chamber (6) are quickly discharged during pressure reduction, and the pressure in the chamber (6) can be reduced to a specific pressure in a short time.

Description

[0001] Information about divisional applications

[0002] This case is a divisional application. The parent case of the divisional application is an invention patent application with application date of July 25, 2019, application number 201910676989.0, and invention name “Heat Treatment Method”. Technical Field

[0003] The present invention relates to a heat treatment method for heating a thin plate-shaped precision electronic substrate (hereinafter simply referred to as a "substrate") such as a semiconductor wafer by irradiating the substrate with light. Background Art

[0004] In the manufacturing process of semiconductor devices, flash lamp annealing (FLA) for heating semiconductor wafers in a very short time has attracted attention. Flash lamp annealing is a heat treatment technology that heats the surface of a semiconductor wafer in a very short time (several milliseconds or less) by irradiating a flash of light onto the surface of the semiconductor wafer using a xenon flash lamp (hereinafter referred to as a "flash lamp").

[0005] The radiation spectrum of a xenon flash lamp is distributed from the ultraviolet region to the near-infrared region, and the wavelength is shorter than that of a conventional halogen lamp, and is roughly consistent with the fundamental absorption band of a silicon semiconductor wafer. Therefore, when a xenon flash lamp is used to irradiate a semiconductor wafer with a flash, less light is transmitted, and the temperature of the semiconductor wafer can be increased rapidly. In addition, it is also known that if the flash irradiation is performed for an extremely short time of a few milliseconds or less, it is possible to selectively increase the temperature only near the surface of the semiconductor wafer.

[0006] This flash lamp annealing is used for a process that requires extremely short-term heating, and is typically used for activation of impurities implanted into a semiconductor wafer. If a flash lamp is irradiated onto the surface of a semiconductor wafer into which impurities have been implanted by ion implantation, the surface of the semiconductor wafer can be heated to the activation temperature in an extremely short time, and only the impurity activation can be performed without causing the impurities to diffuse deeply.

[0007] On the other hand, attempts have also been made to perform flash lamp annealing in an atmosphere of a reactive gas such as ammonia. For example, Patent Document 1 discloses that an ammonia atmosphere is formed in a chamber containing a semiconductor wafer on which a high-k gate insulating film (high-k film) is formed, and the semiconductor wafer is irradiated with a flash to heat it, thereby performing a post-film heat treatment of the high-k gate insulating film. In the apparatus disclosed in Patent Document 1, after the pressure in the chamber containing the semiconductor wafer is reduced, ammonia gas is supplied to form an ammonia atmosphere in the chamber. In addition, in the apparatus disclosed in Patent Document 1, after the heat treatment of the semiconductor wafer in the ammonia atmosphere is performed, the pressure in the chamber is reduced to exhaust harmful ammonia gas, and the semiconductor wafer is removed after replacing it with a nitrogen atmosphere.

[0008] [Background Technology Literature]

[0009] [Patent Document]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 2017-045982 Summary of the invention

[0011] [Problems to be solved by the invention]

[0012] As disclosed in Patent Document 1, when heat treatment of a semiconductor wafer is performed after forming an atmosphere of a reactive gas such as ammonia, it is necessary to perform decompression treatment twice before and after the heat treatment. That is, the pressure in the chamber is reduced before forming the ammonia atmosphere, and the pressure in the chamber is also reduced after the heat treatment in order to discharge the ammonia. Sometimes, semiconductor wafers are processed after forming multiple process gas atmospheres in sequence according to the type of process, in which case the number of decompression treatments will increase further. As a result, if the decompression treatment takes a long time, the processing time for each semiconductor wafer becomes longer and the yield is reduced.

[0013] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a heat treatment method capable of reducing the pressure in a chamber in a short time.

[0014] [Technical means to solve the problem]

[0015] In order to solve the above-mentioned problem, the invention of technical solution 1 is a heat treatment method, which heats a substrate by irradiating light to the substrate, and is characterized in that it includes: a light irradiation step, after pre-heating the substrate by irradiating light from a continuously lit lamp to the substrate held on a base in a chamber, flash heating the substrate by flash irradiation from a flash lamp; a decompression step, exhausting the atmosphere in the chamber to reduce the pressure in the chamber; and a heating step, before the decompression step, heating the atmosphere in the chamber by irradiating light from the continuously lit lamp.

[0016] In addition, the invention according to claim 2 is a heat treatment method according to the invention according to claim 1, characterized in that the heating step is also continuously performed after the decompression step is started.

[0017] In addition, the invention according to claim 3 is a heat treatment method according to the invention according to claim 1 , characterized in that the decompression step and the heating step are performed in the chamber while the substrate is held on the susceptor.

[0018] In addition, the invention according to claim 4 is a heat treatment method according to the invention according to claim 3 , characterized in that the decompression step and the heating step are performed before and after the light irradiation step.

[0019] In addition, the invention according to claim 5 is a heat treatment method according to the invention according to claim 1 , characterized in that the decompression step and the heating step are performed in a state where no substrate exists in the chamber.

[0020] In addition, the invention according to claim 6 is a heat treatment method according to the invention according to claim 5 , characterized in that the decompression step and the heating step are performed before maintenance of the chamber.

[0021] In addition, the invention of technical solution 7 is a heat treatment method according to any one of the inventions of technical solutions 1 to 6, characterized in that in the heating step, the continuous lighting lamp is lit with a fixed power to heat the atmosphere in the chamber.

[0022] In addition, the invention of Technical Solution 8 is a heat treatment method according to any one of the inventions of Technical Solution 1 to Technical Solution 6, characterized in that in the heating process, the output of the continuously lighting lamp is feedback controlled based on the atmosphere temperature in the chamber or the temperature of the base.

[0023] [Effects of the Invention]

[0024] According to the invention of technical solutions 1 to 8, before the atmosphere in the chamber is exhausted and the pressure in the chamber is reduced, the atmosphere in the chamber is heated by irradiating light from continuously lit lamps, so that the thermal motion of gas molecules in the atmosphere is activated and the gas density becomes smaller, so that the pressure in the chamber can be reduced in a short time.

[0025] In particular, according to the invention of claim 2, since the atmosphere in the chamber is heated by continuing to irradiate light from the continuously lit lamp even after the decompression step is started, the chamber can be decompressed in a shorter time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a longitudinal sectional view showing the structure of the heat treatment apparatus of the present invention.

[0027] Figure 2 It is a perspective view showing the overall appearance of the holding portion.

[0028] Figure 3 This is a top view of the base.

[0029] Figure 4 is a cross-sectional view of the base.

[0030] Figure 5 It is a top view of the transfer mechanism.

[0031] Figure 6 It is a side view of the transfer mechanism.

[0032] Figure 7 It is a top view showing the arrangement of a plurality of halogen lamps.

[0033] Figure 8 This is a flowchart showing the processing procedure of the semiconductor wafer according to the first embodiment.

[0034] Fig. 9 It is a graph showing the pressure change in the chamber.

[0035] Fig.10 This is a flowchart showing the processing procedure of replacing the atmosphere in the chamber according to the second embodiment. DETAILED DESCRIPTION

[0036] Below, while referring to the attached Figure 1 Embodiments of the present invention will be described in detail.

[0037] <First Embodiment>

[0038] Figure 1 It is a longitudinal sectional view showing the structure of the heat treatment apparatus 1 of the present invention. Figure 1 The heat treatment device 1 is a flash lamp annealing device that heats a semiconductor wafer W in the shape of a circular plate as a substrate by flash irradiating the semiconductor wafer W. The size of the semiconductor wafer W to be processed is not particularly limited, and may be, 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 transported to the heat treatment device 1, and a post-film formation heat treatment (PDA: Post Deposition Anneal) of the high dielectric constant film is performed by a heat treatment performed by the heat treatment device 1. In addition, Figure 1 In the following drawings, the size or number of each component is exaggerated or simplified as necessary for easy understanding.

[0039] The heat treatment apparatus 1 includes: a chamber 6 for accommodating a semiconductor wafer W; a flash heating unit 5 for housing a plurality of flash lamps FL; and a halogen heating unit 4 for housing a plurality of halogen lamps HL. The flash heating unit 5 is provided on the upper side of the chamber 6, and the halogen heating unit 4 is provided on the lower side. In addition, the heat treatment apparatus 1 includes: a holding unit 7 for holding the semiconductor wafer W in a horizontal position inside the chamber 6; and a transfer mechanism 10 for transferring the semiconductor wafer W between the holding unit 7 and the outside of the apparatus. Furthermore, the heat treatment apparatus 1 includes a control unit 3 for controlling the halogen heating unit 4, the flash heating unit 5, and each operating mechanism provided in the chamber 6 to perform heat treatment of the semiconductor wafer W.

[0040] The chamber 6 is formed by installing chamber windows made of quartz at the top and bottom of a cylindrical chamber side portion 61. The chamber side portion 61 has a generally cylindrical shape with openings at the top and bottom, and an upper chamber window 63 is installed at the upper opening to be closed, and a lower chamber window 64 is installed at the lower opening to be closed. The upper chamber window 63 constituting the top of the chamber 6 is a disk-shaped member formed of quartz, and functions as a quartz window that allows the flash emitted from the flash heating unit 5 to pass into the chamber 6. In addition, the lower chamber window 64 constituting the bottom of the chamber 6 is also a disk-shaped member formed of quartz, and functions as a quartz window that allows the light from the halogen heating unit 4 to pass into the chamber 6.

[0041] In addition, a reflection ring 68 is installed on the upper part of the inner wall of the chamber side portion 61, and a reflection ring 69 is installed on the lower part. The reflection rings 68 and 69 are both formed in a circular ring shape. The upper reflection ring 68 is installed by being embedded from the upper side of the chamber side portion 61. On the other hand, the lower reflection ring 69 is installed by being embedded from the lower side of the chamber side portion 61 and fixed with screws not shown in the figure. In other words, the reflection rings 68 and 69 are both installed on the chamber side portion 61 in a freely loadable and detachable manner. The inner space of the chamber 6, that is, the space surrounded by the upper chamber window 63, the lower chamber window 64, the chamber side portion 61 and the reflection rings 68 and 69 is defined as a heat treatment space 65.

[0042] By installing the reflection rings 68 and 69 on the chamber side portion 61, a recessed portion 62 is formed on the inner wall surface of the chamber 6. That is, the recessed portion 62 is formed to be surrounded by the central portion of the inner wall surface of the chamber side portion 61 where the reflection rings 68 and 69 are not installed, the lower end surface of the reflection ring 68, and the upper end surface of the reflection ring 69. The recessed portion 62 is formed in a circular ring 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 portion 61 and the reflection rings 68 and 69 are formed of a metal material (e.g., stainless steel) having excellent strength and heat resistance.

[0043] In addition, a transport opening (furnace port) 66 for carrying in and out the semiconductor wafer W relative to the chamber 6 is provided in an appropriate shape at the chamber side portion 61. The transport opening 66 can be opened and closed by the gate valve 185. The transport opening 66 is connected to the outer peripheral surface of the recess 62. Therefore, when the gate valve 185 opens the transport opening 66, the semiconductor wafer W can be carried into the heat treatment space 65 through the recess 62 from the transport opening 66 and can be carried out from the heat treatment space 65. In addition, when the gate valve 185 closes the transport opening 66, the heat treatment space 65 in the chamber 6 becomes a closed space.

[0044] Furthermore, a through hole 61a is formed in the chamber side portion 61. A radiation thermometer 20 is installed at a portion of the outer wall surface of the chamber side portion 61 where the through hole 61a is formed. The through hole 61a is a cylindrical hole for guiding infrared light radiated from the lower surface of a semiconductor wafer W held on a susceptor 74 described below to the radiation thermometer 20. The through hole 61a is provided so as to be inclined relative to the horizontal direction in such a manner that the axis of the through hole 61a intersects with the main surface of the semiconductor wafer W held on the susceptor 74. A transparent window 21 made of a barium fluoride material is provided at the end of the through hole 61a on the side facing the heat treatment space 65, through which infrared light in a wavelength range that can be measured by the radiation thermometer 20 is transmitted.

[0045] In addition, a gas supply hole 81 for supplying a processing gas (nitrogen (N2) and ammonia (NH3) in this embodiment) to the heat treatment space 65 is provided in an appropriate shape on the upper part of the inner wall of the chamber 6. The gas supply hole 81 is provided in an appropriate shape at a position higher than the recess 62, and may also be provided at the reflection ring 68. The gas supply hole 81 is connected to the gas supply pipe 83 via 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 83a connected to an ammonia supply source 91, and the other is an inert gas pipe 83b connected to a nitrogen supply source 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 to the inert gas pipe 83b under the control of the control unit 3.

[0046] 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 path of the reactive gas piping 83a. When the supply source valve 93 and the supply valve 96 are opened, ammonia gas is supplied from the ammonia gas supply source 91 to the buffer space 82 through the reactive gas piping 83a and the gas supply pipe 83. The supply confirmation pressure gauge 94 determines whether ammonia gas is supplied from the ammonia gas supply source 91 to the reactive gas piping 83a at a predetermined pressure. The mass flow controller 95 adjusts the flow rate of ammonia gas flowing through the reactive gas piping 83a to a predetermined set value.

[0047] On the other hand, a mass flow controller 97 and a supply valve 98 are inserted in the middle of the path of the inert gas piping 83b. If the supply valve 98 is opened, nitrogen gas is supplied to the buffer space 82 from the nitrogen supply source 92 through the inert gas piping 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 piping 83b to a predetermined set value. When the supply source valve 93, the supply valve 96, and the supply valve 98 are all opened, the ammonia gas supplied from the reactive gas piping 83a and the nitrogen gas supplied from the inert gas piping 83b merge in the gas supply pipe 83, and the mixed gas of the ammonia gas and the nitrogen gas is supplied to the buffer space 82.

[0048] In addition, a bypass pipe 84 is provided to connect the reactive gas pipe 83a and the inert gas pipe 83b. The bypass pipe 84 connects the portion between the supply source valve 93 and the supply confirmation pressure gauge 94 of the reactive gas pipe 83a and the portion between the nitrogen gas supply source 92 and the mass flow controller 97 of the inert gas pipe 83b. A bypass valve 85 is inserted in the bypass pipe 84. When the bypass valve 85 is opened, the reactive gas pipe 83a and the inert gas pipe 83b are in a connected state.

[0049] The processing gas supplied from the gas supply pipe 83 and flowing into the buffer space 82 diffuses in the buffer space 82 having a fluid resistance smaller than that of the gas supply hole 81 and fills the buffer space 82. The processing gas filling the buffer space 82 is supplied from the gas supply hole 81 into the heat treatment space 65.

[0050] A gas exhaust hole 86 for exhausting the gas in the heat treatment space 65 is provided in an appropriate shape at the lower part of the inner wall of the chamber 6. The gas exhaust hole 86 is provided in an appropriate shape at a position lower than the recess 62, and may also be provided at the reflection ring 69. The gas exhaust hole 86 is connected to the 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. In addition, an exhaust valve 89 and a vacuum pressure gauge 191 are inserted in the middle of the path of the gas exhaust pipe 88. If the exhaust valve 89 is opened, the gas in the heat treatment space 65 is discharged from the gas exhaust hole 86 through the buffer space 87 to the gas exhaust pipe 88. The vacuum pressure gauge 191 directly measures the pressure of the gas exhaust pipe 88. Since the pressure at the part of the gas exhaust pipe 88 where the vacuum pressure gauge 191 is provided is substantially the same as the pressure in the chamber 6, the pressure measured by the vacuum pressure gauge 191 is also the pressure in the chamber 6. In addition, a plurality of gas supply holes 81 and gas exhaust holes 86 may be provided along the circumferential direction of the chamber 6 and may also be slit-shaped.

[0051] As the exhaust section 190, an exhaust entity of a factory in which a vacuum pump or the heat treatment apparatus 1 is installed can be used. If a vacuum pump is used as the exhaust section 190, the atmosphere of the heat treatment space 65 as a closed space is exhausted without supplying any gas from the gas supply hole 81, and the pressure in the chamber 6 can be reduced to a vacuum atmosphere. In addition, when a vacuum pump is not used as the exhaust section 190, the pressure in the chamber 6 can be reduced to a pressure less than the atmospheric pressure by exhausting the gas without supplying gas from the gas supply hole 81. The pressure in the reduced pressure chamber 6 is measured by the vacuum pressure gauge 191.

[0052] Figure 2 : is a perspective view showing the overall appearance of the holding part 7. The holding part 7 is composed of a base ring 71, a connecting part 72, and a base 74. The base ring 71, the connecting part 72, and the base 74 are all formed of quartz. That is, the entire holding part 7 is formed of quartz.

[0053] The base ring 71 is a quartz member having an arc shape formed by cutting a portion from a circular ring. The cut portion is provided to prevent interference between the transfer arm 11 of the transfer mechanism 10 described below and the base ring 71. The base ring 71 is supported by the wall surface of the chamber 6 by being placed on the bottom surface of the recess 62 (see Figure 1 ). On the upper surface of the base ring 71, a plurality of connecting parts 72 (four in this embodiment) are vertically provided along the circumferential direction of the annular shape. The connecting part 72 is also a quartz component and is fixed to the base ring 71 by welding.

[0054] The base 74 is supported by four connection parts 72 provided on the base ring 71 . Figure 3 74 is a top view of the base. Figure 4 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 flat plate-shaped member formed of quartz. The diameter of the holding plate 75 is larger than the diameter of the semiconductor wafer W. In other words, the holding plate 75 has a larger plane size than the semiconductor wafer W.

[0055] A guide ring 76 is provided on the peripheral portion of the upper surface of the retaining plate 75. The guide ring 76 is a ring-shaped component 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 periphery of the guide ring 76 is set as a tapered surface that widens upward from the retaining plate 75. The guide ring 76 is formed of the same quartz as the retaining plate 75. The guide ring 76 can be either welded to the upper surface of the retaining plate 75 or fixed to the retaining plate 75 using a separately processed pin or the like. Alternatively, the retaining plate 75 and the guide ring 76 can be processed as an integral component.

[0056] The area on the upper surface of the holding plate 75 that is closer to the inner side than the guide ring 76 is set as a planar holding surface 75a for holding the semiconductor wafer W. On the holding surface 75a of the holding plate 75, a plurality of substrate support pins 77 are erected. In the present embodiment, a total of 12 substrate support pins 77 are erected at intervals of 30° along a circle that is concentric with the outer circumference of the holding surface 75a (the inner circumference of the guide ring 76). The diameter of the circle on which the 12 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, and if the diameter of the semiconductor wafer W is φ300mm, then it is φ270mm to φ280mm (φ270mm in the present embodiment). Each substrate support pin 77 is formed of quartz. The plurality of substrate support pins 77 can be set on the upper surface of the holding plate 75 by welding, or can be processed as one with the holding plate 75.

[0057] Back to Figure 2 The four connecting parts 72 erected on the base ring 71 are fixedly connected to the peripheral part of the holding plate 75 of the base 74 by welding. That is, the base 74 and the base ring 71 are fixedly connected by the connecting parts 72. The base ring 71 of the holding part 7 is supported by the wall surface of the chamber 6, and the holding part 7 is installed in the chamber 6. When the holding part 7 is installed in the chamber 6, the holding plate 75 of the base 74 is in a horizontal posture (a posture in which the normal line is consistent with the vertical direction). In other words, the holding surface 75a of the holding plate 75 is a horizontal plane.

[0058] The semiconductor wafer W carried into the chamber 6 is placed and held in a horizontal position on the susceptor 74 of the holding portion 7 installed in the chamber 6. At this time, the semiconductor wafer W is supported and held on the susceptor 74 by 12 substrate support pins 77 erected on the holding plate 75. More strictly speaking, the upper ends of the 12 substrate support pins 77 contact the lower surface of the semiconductor wafer W to support the semiconductor wafer W. Since the heights of the 12 substrate support pins 77 (the distance from the upper ends of the substrate support pins 77 to the holding surface 75a of the holding plate 75) are uniform, the semiconductor wafer W can be supported in a horizontal position by the 12 substrate support pins 77.

[0059] In addition, the semiconductor wafer W is supported by the plurality of substrate support pins 77 at a certain interval from the holding surface 75a of the holding plate 75. The thickness of the guide ring 76 is greater than the height of the substrate support pins 77. Therefore, the guide ring 76 prevents the semiconductor wafer W supported by the plurality of substrate support pins 77 from being displaced in the horizontal direction.

[0060] In addition, if Figure 2 and Figure 3As shown in FIG. 1 , an opening 78 is formed through the upper and lower sides of the holding plate 75 of the base 74. The opening 78 is provided for the radiation thermometer 20 to receive the radiation light (infrared light) radiated from the lower surface of the semiconductor wafer W. That is, the radiation thermometer 20 receives the light radiated from the lower surface of the semiconductor wafer W through the opening 78 and the transparent window 21 of the through hole 61a installed in the chamber side 61 to measure the temperature of the semiconductor wafer W. Furthermore, the holding plate 75 of the base 74 is penetrated with four through holes 79 for the lift pins 12 of the transfer mechanism 10 described below to pass through and transfer the semiconductor wafer W.

[0061] Figure 5 1 is a top view of the transfer mechanism 10. Figure 6 1 is a side view of the transfer mechanism 10. The transfer mechanism 10 includes two transfer arms 11. The transfer arms 11 are formed in an arc shape along the substantially annular recess 62. Two lift pins 12 are vertically provided on each transfer arm 11. The transfer arms 11 and the lift pins 12 are formed of quartz. Each transfer arm 11 can be rotated by a horizontal moving mechanism 13. The horizontal moving mechanism 13 enables a pair of transfer arms 11 to be in a transfer operation position ( Figure 5 The solid line position), and the retreat position ( Figure 5 The horizontal movement mechanism 13 may be a mechanism that uses individual motors to rotate each transfer arm 11 separately, or a mechanism that uses a link mechanism to rotate a pair of transfer arms 11 in conjunction with one motor.

[0062] In addition, the pair of transfer arms 11 are moved up and down together with the horizontal moving mechanism 13 by the lifting mechanism 14. When the lifting mechanism 14 raises the pair of transfer arms 11 to the transfer operation position, a total of four lift pins 12 pass through the through holes 79 (see FIG. 1 ) provided in the base 74. Figure 2 , 3 ), the upper end of the lift pin 12 protrudes from the upper surface of the base 74. On the other hand, if the lifting mechanism 14 causes the pair of transfer arms 11 to descend in the transfer action position and pulls the lift pin 12 out of the through hole 79, and the horizontal moving mechanism 13 causes the pair of transfer arms 11 to move in an open manner, then each transfer arm 11 moves to a retracted position. The retracted position of the pair of transfer arms 11 is directly above the base ring 71 of the holding portion 7. Since the base ring 71 is placed on the bottom surface of the recess 62, the retracted position of the transfer arm 11 becomes the inner side of the recess 62. In addition, an exhaust mechanism (not shown) is also provided near the portion of the transfer mechanism 10 where the drive portion (the horizontal moving mechanism 13 and the lifting mechanism 14) is provided, and is configured to exhaust the atmosphere around the drive portion of the transfer mechanism 10 to the outside of the chamber 6.

[0063] In addition, the heat treatment apparatus 1 includes an atmosphere thermometer 28 for measuring the atmosphere temperature in the chamber 6 and a radiation thermometer 29 for measuring the temperature of the susceptor 74. The atmosphere thermometer 28 is formed using, for example, a thermocouple. The radiation thermometer 29 receives infrared light radiated from the quartz susceptor 74 and measures the temperature of the susceptor 74 based on the intensity of the infrared light.

[0064] Back to Figure 1 The flash heating unit 5 disposed above the chamber 6 is composed of a light source including a plurality of (30 in this embodiment) xenon flash lamps FL on the inner side of a housing 51, and a reflector 52 disposed so as to cover the upper side of the light source. In addition, a light radiation window 53 is provided at the bottom of the housing 51 of the flash heating unit 5. The light radiation window 53 constituting the bottom of the flash heating unit 5 is a plate-shaped quartz window formed of quartz. By disposing the flash heating unit 5 above the chamber 6, the light radiation 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 light radiation window 53 and the upper chamber window 63.

[0065] The plurality of flash lamps FL are rod-shaped lamps each having a long cylindrical shape, and are arranged in a plane so that their respective length directions are parallel to each other along the main surface (that is, along the horizontal direction) of the semiconductor wafer W held by the holding portion 7. 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.

[0066] The xenon flash lamp FL includes: a rod-shaped glass tube (discharge tube) in which xenon gas is sealed and at both ends of which are provided an anode and a cathode connected to a capacitor; and a trigger electrode attached to the outer peripheral surface of the glass tube. Since xenon gas is an electrical insulator, even if electric charge is stored in the capacitor, no electricity flows in the glass tube under normal conditions. However, when a high voltage is applied to the trigger electrode to break the insulation, the electricity stored in the capacitor flows in the glass tube instantly, and light is emitted by the excitation of xenon atoms or molecules at this time. In this xenon flash lamp FL, since the electrostatic energy stored in the capacitor in advance is converted into an extremely short light pulse of 0.1 milliseconds to 100 milliseconds, it has the characteristic of being able to emit extremely strong light compared to a light source that is continuously lit like a halogen lamp HL. In other words, the flash lamp FL is a pulse light lamp that emits light instantly in an extremely short time of less than 1 second. In addition, the light emission time of the flash lamp FL can be adjusted according to the coil constant of the lamp power supply that supplies power to the flash lamp FL.

[0067] In addition, the reflector 52 is provided above the plurality of flash lamps FL so as to cover them all. The basic function of the reflector 52 is to reflect the flash emitted from the plurality of flash lamps FL toward the heat treatment space 65. The reflector 52 is formed of an aluminum alloy plate, and its surface (the surface facing the flash lamp FL) is roughened by sandblasting.

[0068] The halogen heating unit 4 disposed below the chamber 6 has a plurality of (40 in this embodiment) halogen lamps HL built inside a housing 41. The halogen heating unit 4 is a light irradiation unit that heats the semiconductor wafer W by irradiating a heat treatment space 65 with light from below the chamber 6 through a lower chamber window 64 using a plurality of halogen lamps HL.

[0069] Figure 7 It is a top view showing the arrangement of a plurality of halogen lamps HL. 40 halogen lamps HL are arranged in two levels, upper and lower. 20 halogen lamps HL are arranged at the upper level close to the holding portion 7, and 20 halogen lamps HL are also arranged at the lower level farther from the holding portion 7 than the upper level. Each halogen lamp HL is a rod-shaped lamp having a long cylindrical shape. The 20 halogen lamps HL at both the upper and lower levels are arranged in parallel with each other along the main surface of the semiconductor wafer W held in the holding portion 7 (that is, in the horizontal direction) in their respective length directions. Therefore, the plane formed by the arrangement of the halogen lamps HL is a horizontal plane at both the upper and lower levels.

[0070] In addition, if Figure 7 As shown, the arrangement density of the halogen lamps HL in the area opposite to the peripheral part of the semiconductor wafer W held in the holding part 7 is higher in both the upper and lower stages than in the area opposite to the central part of the semiconductor wafer W held in the holding part 7. That is, the arrangement spacing of the halogen lamps HL in the peripheral part is shorter than that in the central part of the lamp arrangement in both the upper and lower stages. Therefore, when heating is performed by light irradiation from the halogen heating part 4, a larger amount of light can be irradiated to the peripheral part of the semiconductor wafer W, which is prone to temperature drop.

[0071] In addition, the lamp group including the upper halogen lamps HL and the lamp group including the lower halogen lamps HL are arranged in a lattice-like manner. In other words, a total of 40 halogen lamps HL are arranged so that the length directions of the 20 halogen lamps HL arranged in the upper stage and the length directions of the 20 halogen lamps HL arranged in the lower stage are orthogonal to each other.

[0072] The halogen lamp HL is a filament-type light source that emits light by energizing a filament disposed inside a glass tube to turn the filament incandescent. Inside the glass tube, a gas obtained by introducing a trace amount of halogen elements (iodine, bromine, etc.) into an inert gas such as nitrogen or argon is sealed. By introducing the halogen element, the breakage of the filament can be suppressed, and the temperature of the filament can be set to a high temperature. Therefore, the halogen lamp HL has the characteristics of a longer life and the ability to continuously irradiate stronger light compared to a conventional incandescent bulb. In other words, the halogen lamp HL is a continuously lit lamp that emits light continuously for at least 1 second. In addition, since the halogen lamp HL is a rod-shaped lamp, it has a longer life, and by arranging the halogen lamp HL in the horizontal direction, the radiation efficiency to the semiconductor wafer W above becomes excellent.

[0073] In addition, a reflector 43 ( Figure 1 ). The reflector 43 reflects the light emitted from the plurality of halogen lamps HL toward the heat treatment space 65 side.

[0074] The control unit 3 controls the various action mechanisms provided in the heat treatment device 1. The hardware structure of the control unit 3 is the same as that of an ordinary computer. That is, the control unit 3 has a CPU (Central Processing Unit) as a circuit for performing various calculations, a ROM (Read Only Memory) as a dedicated memory for reading out basic programs, a RAM (Random Access Memory) as a freely readable and writable memory for storing various information, and a disk that pre-stores control software or data. The processing in the heat treatment device 1 is performed by executing a specific processing program by the CPU of the control unit 3.

[0075] In addition to the above-mentioned configuration, the heat treatment apparatus 1 also has various cooling structures to prevent excessive temperature rise of the halogen heating unit 4, the flash heating unit 5, and the chamber 6 caused by the heat energy generated by the halogen lamp HL and the flash lamp FL during the heat treatment of the semiconductor wafer W. For example, a water cooling pipe (not shown) is provided on the wall of the chamber 6. In addition, the halogen heating unit 4 and the flash heating unit 5 are provided with an air cooling structure for exhausting heat by forming a gas flow inside. In addition, air is also supplied to the gap between the upper chamber window 63 and the lamp radiation window 53 to cool the flash heating unit 5 and the upper chamber window 63.

[0076] Next, the processing operation in the heat treatment apparatus 1 will be described. Figure 8This is a flowchart showing the processing sequence of the semiconductor wafer W of the first embodiment. The semiconductor wafer W to be processed here is a semiconductor substrate of silicon 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 methods such as ALD (Atomic Layer Deposition) or MOCVD (Metal Organic Chemical Vapor Deposition). The semiconductor wafer W is irradiated with a flash in an ammonia atmosphere by a heat treatment device 1 to perform post-film formation heat treatment (PDA), so that defects in the high dielectric constant film after film formation disappear. The processing sequence of the heat treatment device 1 to be described below is performed by the control unit 3 controlling each action mechanism of the heat treatment device 1.

[0077] First, a semiconductor wafer W having a high dielectric constant film formed thereon is moved into the chamber 6 of the heat treatment apparatus 1 (step S11). When the semiconductor wafer W is moved in, the gate valve 185 is opened and the transport opening 66 is opened, and the semiconductor wafer W having a high dielectric constant film formed thereon is moved into the heat treatment space 65 in the chamber 6 through the transport opening 66 by a transport robot outside the apparatus. At this time, since both the inside and outside of the chamber 6 are at atmospheric pressure, the atmosphere outside the apparatus is entrained into the heat treatment space 65 in the chamber 6 as the semiconductor wafer W is moved in. Therefore, the nitrogen gas flow may be made to flow out from the transport opening 66 by opening the supply valve 98 and continuously supplying nitrogen gas to the chamber 6 from the nitrogen supply source 92, thereby minimizing the inflow of the atmosphere outside the apparatus into the chamber 6. Furthermore, when the gate valve 185 is opened, it is preferred that the exhaust valve 89 be closed to stop exhausting gas from the chamber 6. Thus, the nitrogen gas supplied into the chamber 6 flows out only from the transfer opening 66 , and thus the inflow of the external atmosphere can be more effectively prevented.

[0078] The semiconductor wafer W carried in by the transfer robot is moved in and out to the position just above the holding portion 7 and then stops. Then, the pair of transfer arms 11 of the transfer mechanism 10 are horizontally moved from the retreat position to the transfer operation position and rise, and the lift pins 12 protrude from the upper surface of the holding plate 75 of the base 74 through the through holes 79 to receive the semiconductor wafer W. At this time, the lift pins 12 rise to a position higher than the upper ends of the substrate support pins 77.

[0079] After placing the semiconductor wafer W on the lift pins 12, the transport robot withdraws from the heat treatment space 65, and the transport opening 66 is closed by the gate valve 185. Then, the semiconductor wafer W is transferred from the transport mechanism 10 to the base 74 of the holding portion 7 by the pair of transfer arms 11 descending, and is held from below in a horizontal posture. The semiconductor wafer W is supported by a plurality of substrate support pins 77 vertically provided on the holding plate 75 and held on the base 74. In addition, the semiconductor wafer W is held on the base 74 with the surface on which the high dielectric constant film is formed as the upper surface. A specific gap is formed between the back surface (the main surface on the opposite side to the front side) 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 the bottom of the base 74 are retreated to the retreat position, that is, the inside of the recess 62 by the horizontal moving mechanism 13.

[0080] After the semiconductor wafer W is accommodated 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. Fig. 9 2 is a graph showing the pressure change in the chamber 6. The horizontal axis of the graph represents time, and the vertical axis represents the pressure in the chamber 6. At time t1 when the semiconductor wafer W is accommodated in the chamber 6 and the transfer opening 66 is closed, the pressure in the chamber 6 is normal pressure Ps (= atmospheric pressure = about 101325 Pa).

[0081] In the first embodiment, at time t2 before the pressure in the chamber 6 is reduced, the halogen lamp HL of the halogen heating unit 4 irradiates light to heat the atmosphere in the chamber 6 (step S12). A portion of the light irradiated from the halogen lamp HL is directly absorbed by the gas molecules in the atmosphere in the chamber 6, and the temperature of the atmosphere rises. In addition, a portion of the light irradiated from the halogen lamp HL is absorbed by the semiconductor wafer W held on the susceptor 74, and the atmosphere in the chamber 6 is also heated by heat transfer from the heated semiconductor wafer W.

[0082] When the atmosphere in the chamber 6 is heated by irradiation with light from the halogen lamp HL, the temperature of the atmosphere in the chamber 6 is measured by the atmosphere thermometer 28. The atmosphere temperature in the chamber 6 measured by the atmosphere thermometer 28 is transmitted to the control unit 3. The control unit 3 performs feedback control on the output of the halogen lamp HL in such a manner that the atmosphere temperature in the chamber 6 becomes the target temperature TP based on the measured value by the atmosphere thermometer 28. The temperature increase rate of the atmosphere temperature in the chamber 6 and the target temperature TP are not particularly limited, for example, the temperature increase rate is 20°C / second and the target temperature TP is 250°C. That is, the control unit 3 performs feedback control on the output of the halogen lamp HL in such a manner that the measured value by the atmosphere thermometer 28 is a temperature increase rate of 20°C / second and becomes 250°C.

[0083] At time t3 after the atmosphere temperature in the chamber 6 reaches the target temperature TP, the decompression in the chamber 6 is started (step S13). Specifically, by closing the transfer opening 66, the heat treatment space 65 in the chamber 6 becomes a closed space. In this state, the supply valve 96 and the supply valve 98 for gas supply are closed, and the exhaust valve 89 is opened. Thus, the heat treatment space 65 in the chamber 6 is decompressed to less than the atmospheric pressure without supplying gas to the chamber 6. In the initial stage of decompression, the exhaust unit 190 exhausts the atmosphere in the chamber 6 at a relatively small exhaust flow rate to decompress the chamber 6.

[0084] Next, at time t4 when the pressure in the chamber 6 measured by the vacuum pressure gauge 191 is reduced to the air pressure P1, the exhaust flow rate of the exhaust unit 190 is increased, and the exhaust speed is also increased. The air pressure P1 is, for example, about 20000 Pa. Then, at time t5, the pressure (vacuum degree) in the chamber 6 reaches the air pressure P2. The air pressure P2 is, for example, about 100 Pa. That is, after exhausting at a relatively small exhaust flow rate in the initial stage of the decompression, the exhaust is switched to an exhaust flow rate greater than the air pressure.

[0085] If exhaust is performed quickly at a large exhaust flow rate from the start of decompression, a large airflow change occurs in the chamber 6, and particles attached to the structure of the chamber 6 (for example, the lower chamber window 64) may be rolled up and attached to the semiconductor wafer W to cause contamination. If exhaust is performed quietly at a small exhaust flow rate in the initial stage of decompression and then switched to a large exhaust flow rate for exhaust, such rolling up of particles in the chamber 6 can be prevented.

[0086] At time t5 when the pressure in the chamber 6 reaches the gas pressure P2, the supply of the processing gas into the chamber 6 is started (step S14). Specifically, the exhaust valve 89 is opened, and the supply source valve 93, the supply valve 96 and the supply valve 98 are opened. By opening the supply source valve 93 and the supply valve 96, ammonia is supplied from the reactive gas pipe 83a. In addition, by opening the supply valve 98, nitrogen is supplied from the inert gas pipe 83b. The supplied ammonia and nitrogen merge in the gas supply pipe 83. Then, a mixed gas of ammonia and nitrogen is supplied to the heat treatment space 65 in the chamber 6. As a result, an ammonia atmosphere is formed in a reduced pressure state around the semiconductor wafer W held in the holding part 7 in the chamber 6. The concentration of ammonia in the ammonia atmosphere (i.e., the mixing ratio of ammonia and nitrogen) is not particularly limited, and can be set to an appropriate value, for example, as long as it is 10 vol.% or less (about 2.5 vol.% in this embodiment). The concentration of the ammonia gas can be adjusted by controlling the supply flow rates of the ammonia gas and the nitrogen gas using the mass flow controller 95 and the mass flow controller 97 , respectively.

[0087] By supplying a mixed gas of ammonia and nitrogen into the chamber 6, the pressure in the chamber 6 rises from the gas pressure P2 and is raised to the gas pressure P3 at time t6. The gas pressure P3 is, for example, about 5000 Pa. Since the pressure in the chamber 6 is temporarily reduced to the gas pressure P2 and then raised to the gas pressure P3, the oxygen concentration in the ammonia atmosphere formed in the chamber 6 can be made extremely low. After time t6 when the pressure in the chamber 6 is raised to the gas pressure P3, the supply flow rate of the mixed gas of ammonia and nitrogen to the chamber 6 is made equal to the exhaust flow rate from the chamber 6 to maintain the pressure in the chamber 6 at the gas pressure P3.

[0088] Next, after the time t6 when the pressure in the chamber 6 is increased to the air pressure P3, the semiconductor wafer W is subjected to a heating treatment (step S15). First, the semiconductor wafer W is preheated (auxiliary heating) by light irradiation from 40 halogen lamps HL of the halogen heating unit 4. The halogen light emitted from the halogen lamp HL passes through the lower chamber window 64 and the base 74 formed by quartz and irradiates the lower surface of the semiconductor wafer W. The semiconductor wafer W is preheated by receiving the light irradiation from the halogen lamp HL and the temperature rises. In addition, since the transfer arm 11 of the transfer mechanism 10 retreats to the inner side of the recess 62, it does not become an obstacle to the heating by the halogen lamp HL.

[0089] When preheating using the halogen lamp HL is performed, the temperature of the semiconductor wafer W is measured using the radiation thermometer 20. That is, the radiation thermometer 20 receives infrared light radiated from the lower surface of the semiconductor wafer W held on the susceptor 74 through the opening 78 through the transparent window 21 to measure the temperature of the wafer during heating. 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 the temperature of the semiconductor wafer W heated by the light irradiation from the halogen lamp HL reaches a specific preheating temperature T1. That is, the control unit 3 performs feedback control on the output of the halogen lamp HL based on the measured value using the radiation thermometer 20 so that the temperature of the semiconductor wafer W reaches the preheating temperature T1. The preheating temperature T1 is not less than 300°C and not more than 600°C, and is 450°C in the present embodiment.

[0090] 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, at the time point 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 maintain the temperature of the semiconductor wafer W approximately at the preheating temperature T1.

[0091] By performing such preheating with the halogen lamp HL, the temperature of the entire semiconductor wafer W is uniformly raised to the preheating temperature T1. In the preheating stage with the halogen lamp HL, there is a tendency that the temperature of the peripheral portion of the semiconductor wafer W, which is more likely to generate heat dissipation, is lower than that of the central portion, but the arrangement density of the halogen lamp HL in the halogen heating unit 4 is higher in the area facing the peripheral portion than in the area facing the central portion of the semiconductor wafer W. Therefore, the amount of light irradiated to the peripheral portion of the semiconductor wafer W, which is more likely to generate heat dissipation, becomes larger, and the in-plane temperature distribution of the semiconductor wafer W in the preheating stage can be made uniform.

[0092] At time t7 after a specific time has passed since the temperature of the semiconductor wafer W reaches the preheating temperature T1, the flash lamp FL of the flash heating unit 5 flash-irradiates the surface of the semiconductor wafer W held on the susceptor 74. At this time, a part of the flash radiated from the flash lamp FL is directed directly into the chamber 6, and another part is temporarily reflected by the reflector 52 and then directed into the chamber 6, and the semiconductor wafer W is flash-heated by the irradiation of these flashes.

[0093] Since flash heating is performed by flashlight irradiation from the flash lamp FL, the surface temperature of the semiconductor wafer W can be raised in a short time. That is, the flashlight irradiated from the flash lamp FL is an extremely short and strong flashlight that converts the electrostatic energy previously stored in the capacitor into an extremely short light pulse, and the irradiation time is approximately 0.1 milliseconds or more and 100 milliseconds or less. In addition, by irradiating the surface of the semiconductor wafer W on which the high dielectric constant film is formed with flashlight from the flash lamp FL, the surface of the semiconductor wafer W including the high dielectric constant film is instantly heated to the processing temperature T2, and then a post-film formation heat treatment is performed. The highest temperature (peak temperature) reached by the surface of the semiconductor wafer W by the flash irradiation, that is, the processing temperature T2, is 600°C or more and 1200°C or less, and is 1000°C in the present embodiment.

[0094] If the post-film formation heat treatment is performed after the surface temperature of the semiconductor wafer W is raised to the processing temperature T2 in the ammonia atmosphere, the nitridation of the high dielectric constant film is promoted, and defects such as point defects existing in the high dielectric constant film disappear. In addition, since the irradiation time from the flash lamp FL is a short time of about 0.1 milliseconds or more and 100 milliseconds or less, the time required for the surface temperature of the semiconductor wafer W to rise from the preheating temperature T1 to the processing temperature T2 is also an extremely short time of less than 1 second. The surface temperature of the semiconductor wafer W after the flash irradiation immediately drops rapidly from the processing temperature T2.

[0095] After the flash heating process is completed, the atmosphere in the chamber 6 is heated again by light irradiation from the halogen lamp HL at time t8 (step S16). As in step S12, the atmosphere in the chamber 6 is directly heated by light irradiation from the halogen lamp HL, and in addition, the atmosphere in the chamber 6 is indirectly heated by heat transfer from the heated semiconductor wafer W. In addition, the control unit 3 performs feedback control on the output of the halogen lamp HL based on the measured value of the atmosphere thermometer 28 so that the atmosphere temperature in the chamber 6 becomes the target temperature TP.

[0096] At time t9 after the atmosphere temperature in the chamber 6 reaches the target temperature TP, the pressure reduction in the chamber 6 is started (step S17). That is, the supply valve 96 and the supply valve 98 are closed and the exhaust valve 89 is opened to exhaust the atmosphere in the chamber 6 and reduce the pressure in the chamber 6 again. The pressure in the chamber 6 reaches the pressure P2 at time t10. By exhausting the chamber 6 and reducing the pressure to the pressure P2 again, harmful ammonia gas can be discharged from the heat treatment space 65 in the chamber 6.

[0097] Next, the exhaust valve 89 is closed and the supply valve 98 is opened, and nitrogen is supplied from the nitrogen supply source 92 into the chamber 6 as an inert gas to restore the chamber 6 to normal pressure Ps (step S18). As a result, the chamber 6 is replaced with a nitrogen atmosphere. In addition, the halogen lamp HL is also extinguished, and the semiconductor wafer W is also cooled from the preheating temperature T1. The temperature of the semiconductor wafer W during the cooling process 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 been cooled to a specific temperature based on the measurement result. Then, after the temperature of the semiconductor wafer W is cooled to below a specific temperature, the pair of transfer arms 11 of the transfer mechanism 10 are horizontally moved from the retreat position to the transfer action position again and rise, whereby the lift pin 12 protrudes from the upper surface of the base 74 and receives the heat-treated semiconductor wafer W from the base 74. Next, the transfer opening 66 closed by the gate valve 185 is opened, and the semiconductor wafer W placed on the lift pins 12 is transferred out by a transfer robot outside the apparatus, thereby completing the heat treatment of the semiconductor wafer W in the heat treatment apparatus 1 (step S19).

[0098] In the first embodiment, before exhausting the chamber 6 and reducing the pressure during the processing of the semiconductor wafer W, the atmosphere in the chamber 6 is heated by irradiating light from the halogen lamp HL (step S12 and step S16). By heating the atmosphere in the chamber 6 before reducing the pressure, the thermal motion of the gas molecules in the atmosphere is activated and the gas density becomes smaller. As a result, the gas molecules in the chamber 6 are quickly exhausted during the decompression, and the pressure in the chamber 6 can be reduced to a specific pressure in a short time. As a result, it is possible to prevent the processing time of the semiconductor wafer W accompanying the decompression process from being prolonged and prevent the yield from being reduced.

[0099] In the first embodiment, the atmosphere in the chamber 6 is heated by light irradiation from the halogen lamp HL in the state where the semiconductor wafer W is present in the chamber 6, but the temperature of the semiconductor wafer W when the atmosphere temperature in the chamber 6 reaches the target temperature TP is lower than the preheating temperature T1. Therefore, there is no possibility that the heat treatment history of the semiconductor wafer W is significantly affected by light irradiation from the halogen lamp HL for the decompression treatment.

[0100] <Second Embodiment>

[0101] Next, the second embodiment of the present invention will be described. The configuration of the heat treatment apparatus 1 of the second embodiment and the processing sequence of the semiconductor wafer W are the same as those of the first embodiment. In the first embodiment, when processing the semiconductor wafer W, that is, when the semiconductor wafer W to be processed is held on the susceptor 74, the atmosphere in the chamber 6 is heated before and after the flash heating and then the decompression treatment is performed. In contrast, in the second embodiment, when the maintenance of the heat treatment apparatus 1 is performed, the atmosphere in the chamber 6 is heated and then the decompression treatment is performed.

[0102] The heat treatment device 1 is maintained regularly or irregularly. If the maintenance is performed irregularly, some obstacles may occur to the heat treatment device 1. Whether regularly or irregularly, when the heat treatment device 1 is maintained, the interior of the chamber 6 is opened and various pipes are removed. Therefore, the harmful ammonia must be completely discharged from the heat treatment space 65 in the chamber 6 and the entire heat treatment device 1 including various pipes before maintenance. Therefore, the supply valve 96 is opened to discharge ammonia from the reactive gas pipe 83a in addition to the heat treatment space 65 in the chamber 6.

[0103] Fig.10 1 is a flowchart showing the processing sequence of the atmosphere replacement in the chamber 6 according to the second embodiment. First, in a state where no semiconductor wafer W exists in the chamber 6 before maintenance, light is irradiated from the halogen lamp HL to heat the atmosphere in the chamber 6 (step S21). A portion of the light irradiated from the halogen lamp HL is directly absorbed by the gas molecules of the atmosphere in the chamber 6, and the atmosphere is directly heated. In addition, a portion of the light irradiated by the halogen lamp HL is absorbed by the structures in the chamber 6 such as the susceptor 74, and the atmosphere in the chamber 6 is also indirectly heated by heat transfer from the structures.

[0104] When the atmosphere in the chamber 6 is heated by irradiation with light from the halogen lamp HL, the temperature of the atmosphere in the chamber 6 is measured by the atmosphere thermometer 28. The atmosphere temperature in the chamber 6 measured by the atmosphere thermometer 28 is transmitted to the control unit 3. In the second embodiment, the halogen lamp HL is lit with a fixed power (for example, 30% of the maximum power) to heat the atmosphere in the chamber 6 until the atmosphere temperature in the chamber 6 reaches the target temperature TP. That is, in the first embodiment, the output of the halogen lamp HL is feedback controlled, while in the second embodiment, constant output control is performed. The target temperature TP of the atmosphere temperature in the chamber 6 is, for example, 250° C., similar to the first embodiment.

[0105] After the atmosphere temperature in the chamber 6 reaches the target temperature TP, the pressure reduction in the chamber 6 is started (step S22). Specifically, 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. Thus, the chamber 6 and the reactive gas piping 83a including the mass flow controller 95 (to be precise, the portion downstream of the supply source valve 93) are exhausted from the gas exhaust pipe 88, and not only the pressure in the chamber 6 but also the pressure in the reactive gas piping 83a is reduced. As a result, the ammonia gas remaining in the reactive gas piping 83a is also exhausted.

[0106] Next, after the pressure in the chamber 6 measured by the vacuum pressure gauge 191 is reduced to a specific pressure, the pressure reduction is stopped and the nitrogen gas supply to the reactive gas piping 83a and the chamber 6 is performed (step S23). At this time, the supply source valve 93 and the exhaust valve 89 are closed, and the supply valve 96, the supply valve 98 and the bypass valve 85 are opened. As a result, a part of the nitrogen gas supplied from the nitrogen supply source 92 is filled into the reactive gas piping 83a including the mass flow controller 95 (to be precise, the portion between the supply source valve 93 and the supply valve 96) through the bypass piping 84. In addition, the nitrogen gas supplied from the nitrogen supply source 92 is also filled into the chamber 6.

[0107] After the chamber 6 and the reactive gas piping 83a are filled with nitrogen, the process proceeds to step S24, where the control unit 3 determines whether the decompression process and the nitrogen supply have been repeated for a set number of times. In the control unit 3, for example, the set number of repetitions is pre-set using a GUI (Graphical User Interface). If the decompression process and the nitrogen supply have not been repeated for a set number of times, the decompression process of step S22 and the nitrogen supply of step S23 are repeated again. For example, if "10" is set as the set number of repetitions, the decompression process and the nitrogen supply are repeated 10 times. As a result, ammonia is effectively discharged from the reactive gas piping 83a and the chamber 6 and filled with nitrogen.

[0108] In the second embodiment, before the maintenance of the heat treatment device 1, the atmosphere in the chamber 6 is heated by irradiating light from the halogen lamp HL, and then the chamber 6 is exhausted to reduce the pressure. By heating the atmosphere in the chamber 6 before reducing the pressure, the thermal motion of the gas molecules in the atmosphere is activated and the gas density becomes smaller. As a result, similar to the first embodiment, the gas molecules in the chamber 6 are quickly discharged during the decompression, and the chamber 6 can be decompressed to a specific pressure in a short time. As a result, the time required for nitrogen flushing before maintenance can be shortened.

[0109] <Example of variation>

[0110] The embodiments of the present invention have been described above, but the present invention can be modified in various ways other than the above as long as it does not deviate from the main purpose. For example, in the first and second embodiments, the atmosphere in the chamber 6 is heated before the pressure in the chamber 6 is reduced. However, in addition to this, the atmosphere in the chamber 6 can also be heated by continuing to irradiate light from the halogen lamp HL after the pressure in the chamber 6 is reduced. By heating the atmosphere in the chamber 6 by irradiating light from the halogen lamp HL after the pressure in the chamber 6 is reduced, the pressure in the chamber 6 can be reduced in a shorter time. Alternatively, the atmosphere in the chamber 6 can be heated by irradiating light from the halogen lamp HL after the pressure in the chamber 6 is reduced.

[0111] In addition, in the first embodiment, the output of the halogen lamp HL is feedback controlled, but instead, the halogen lamp HL may be lit with a fixed power as in the second embodiment to heat the atmosphere in the chamber 6 until the atmosphere temperature in the chamber 6 reaches the target temperature TP. On the contrary, in the second embodiment, the output of the halogen lamp HL may be feedback controlled in such a way that the atmosphere temperature in the chamber 6 reaches the target temperature TP based on the measured value using the atmosphere thermometer 28. That is, whether the output of the halogen lamp HL is feedback controlled or constant output controlled may be appropriately selected. Alternatively, feedback control and constant output control may be combined. For example, the output of the halogen lamp HL may be constant output controlled during a period when the atmosphere temperature in the chamber 6 is relatively low, and the output of the halogen lamp HL may be feedback controlled after the atmosphere temperature approaches the target temperature TP.

[0112] Furthermore, when the output of the halogen lamp HL is feedback-controlled, the output of the halogen lamp HL may be feedback-controlled based on the temperature of the susceptor 74 measured by the radiation thermometer 29 or the temperature of the semiconductor wafer W measured by the radiation thermometer 20 instead of the ambient temperature in the chamber 6. However, as in the first embodiment, the output of the halogen lamp HL is feedback-controlled based on the ambient temperature in the chamber 6 measured by the ambient thermometer 28, and the ambient temperature in the chamber 6 can be directly set to the target temperature TP.

[0113] In addition, in the above-described embodiment, ammonia gas is supplied from the reactive gas pipe 83a, but the present invention is not limited thereto, and oxygen (O2), hydrogen (H2), chlorine (Cl2), hydrogen chloride (HCl), ozone (O3), nitric oxide (NO), nitrous oxide (N2O), nitrogen dioxide (NO2), nitrogen trifluoride (NF3), etc. may be supplied from the reactive gas pipe 83a as reactive gas. In addition, the gas supplied from the inert gas pipe 83b is not limited to nitrogen gas, and argon (Ar), helium (He), etc. may be supplied from the inert gas pipe 83b as inert gas.

[0114] In the first embodiment, the heat treatment of the semiconductor wafer W is performed after the ammonia atmosphere is formed in the chamber 6, but the semiconductor wafer W may be processed after a plurality of different atmospheres are sequentially formed in the chamber 6. In this case, since the pressure in the chamber 6 is reduced several times during the processing of one semiconductor wafer W, the processing time can be shortened by preferably applying the technology of the present invention and reducing the pressure in the chamber 6 for a short time each time.

[0115] In the above embodiment, the flash heating unit 5 includes 30 flash lamps FL, but the present invention is not limited thereto, and the number of flash lamps FL can be set to any number. In addition, the flash lamp FL is not limited to a xenon flash lamp, and can also be a krypton flash lamp. In addition, the number of halogen lamps HL included in the halogen heating unit 4 is not limited to 40, and can be set to any number.

[0116] In addition, in the above-described embodiment, a filament-type halogen lamp HL is used as a continuous-lighting lamp that continuously emits light for more than 1 second to preheat the semiconductor wafer W, but the present invention is not limited thereto, and a discharge-type arc lamp (e.g., a xenon arc lamp) may be used as a continuous-lighting lamp instead of the halogen lamp HL to preheat the semiconductor wafer W. In this case, the atmosphere in the chamber 6 is heated by light irradiation from the arc lamp before the decompression treatment.

[0117] In addition, 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 in a flat panel display such as a liquid crystal display device or a substrate for a solar cell. In addition, in the heat treatment apparatus 1, activation of injected impurities, bonding of metal and silicon, or crystallization of polycrystalline silicon may also be performed.

[0118] [Explanation of symbols]

[0119] 1 Heat treatment device

[0120] 3. Control Unit

[0121] 4 Halogen heating unit

[0122] 5 Flash heating unit

[0123] 6 Chamber

[0124] 7. Maintaining part

[0125] 10 Transfer mechanism

[0126] 20, 29 Radiation thermometer

[0127] 28 Atmosphere thermometer

[0128] 65 Heat treatment space

[0129] 74 Base

[0130] 75 Holding Plate

[0131] 77 Base plate support pin

[0132] 83 Gas supply pipe

[0133] 83a Reactive gas piping

[0134] 83b Inert gas piping

[0135] 84 Bypass piping

[0136] 85 Bypass valve

[0137] 88 Gas exhaust pipe

[0138] 89 Exhaust valve

[0139] 91 Ammonia supply source

[0140] 92 Nitrogen supply source

[0141] 93 Supply source valve

[0142] 96, 98 supply valve

[0143] 190 Exhaust

[0144] 191 Vacuum pressure gauge

[0145] FL Flash

[0146] HL halogen lamp

[0147] W Semiconductor Wafer

Claims

1. A heat treatment method, characterized in that: The method heats a substrate by irradiating light onto the substrate, and comprises: a light irradiation step of flash-heating the substrate by flash irradiation from a flash lamp after preheating the substrate by irradiating the substrate held on a susceptor in a chamber with light from a continuously lit lamp; a decompression step of exhausting the atmosphere in the chamber to reduce the pressure in the chamber; and a heating step of heating the atmosphere in the chamber by irradiating light from the continuously lit lamp before the decompression step; The decompression step and the heating step are performed in a state where no substrate is present in the chamber.

2. The heat treatment method according to claim 1, characterized in that The decompression process and the heating process are performed before maintenance of the chamber.

3. The heat treatment method according to claim 1 or 2, characterized in that: In the heating step, the continuous lighting lamp is lit at a fixed power to heat the atmosphere in the chamber.

4. The heat treatment method according to claim 1 or 2, characterized in that: In the heating step, the output of the continuous lighting lamp is feedback-controlled based on the ambient temperature in the chamber or the temperature of the susceptor.

Images