Heat treatment apparatus and heat treatment method

Abstract

To provide a heat treatment device and a heat treatment method, capable of correcting a warp of a substrate.SOLUTION: A semiconductor wafer carried in a chamber is held by a susceptor. The semiconductor wafer held by the susceptor is irradiated with light by a plurality of halogen lamps and the semiconductor wafer is preheated. A warp of the semiconductor wafer held by the susceptor is detected by a plurality of detection units. When a warp of the semiconductor wafer is detected, a control unit controls radiation light intensity of the plurality of halogen lamps so as to eliminate the warp. Thereby, even when a warp caused by heat influence is generated in the semiconductor wafer, the warp of the semiconductor wafer can be corrected. By a flash lamp irradiating a surface of the semiconductor wafer whose warp is corrected with flash light, cracks of the semiconductor wafer can be prevented when the wafer is quickly heated.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a heat treatment apparatus and a heat treatment method for heating a thin precision electronic substrate such as a semiconductor wafer (hereinafter simply referred to as a "substrate") by irradiating the substrate with light. [Background technology]

[0002] Flash lamp annealing (FLA), which heats semiconductor wafers in an extremely short time, has been attracting attention in the semiconductor device manufacturing process. Flash lamp annealing is a heat treatment technique that uses a xenon flash lamp (hereinafter, simply "flash lamp" means a xenon flash lamp) to irradiate the surface of a semiconductor wafer with a flash of light, thereby raising the temperature of only the surface of the semiconductor wafer in an extremely short time (several milliseconds or less).

[0003] The spectral distribution of radiation from a xenon flash lamp is in the ultraviolet to near infrared range, and has a shorter wavelength than conventional halogen lamps, which almost matches the fundamental absorption band of silicon semiconductor wafers. Therefore, when a semiconductor wafer is irradiated with flash light from a xenon flash lamp, there is little transmitted light, and it is possible to rapidly heat the semiconductor wafer. It has also been found that if the flash light is irradiated for an extremely short period of time, less than a few milliseconds, it is possible to selectively heat only the vicinity of the surface of the semiconductor wafer.

[0004] Such flash lamp annealing is used in processes that require heating for an extremely short time, such as activating impurities typically implanted in semiconductor wafers. By irradiating the surface of a semiconductor wafer into which impurities have been implanted by ion implantation with a flash light from a flash lamp, the surface of the semiconductor wafer can be heated to the activation temperature for an extremely short time, and only the impurity activation can be performed without deep diffusion of the impurities.

[0005] A heat treatment apparatus that typically performs such flash lamp annealing has a flash lamp above a chamber that contains a semiconductor wafer and a halogen lamp below it (for example, Patent Document 1). In the apparatus disclosed in Patent Document 1, the semiconductor wafer is preheated by light irradiation from a halogen lamp, and then the surface of the semiconductor wafer is irradiated with flash light from the flash lamp. Preheating is performed with a halogen lamp because it is difficult for the surface of the semiconductor wafer to reach the target temperature by flash light irradiation alone. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2011-159713 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, when a semiconductor wafer is preheated by irradiation with light from a halogen lamp, the semiconductor wafer frequently warps. Possible causes of the semiconductor wafer warping during preheating include the central part of the semiconductor wafer being excessively hotter than the peripheral part due to the power balance of the halogen lamp, or a film with high light absorption properties being formed on the back surface of the semiconductor wafer. Regardless of the cause, if a flash light is irradiated on a semiconductor wafer in a warped state, the semiconductor wafer may crack.

[0008] 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 apparatus and a heat treatment method capable of correcting warpage of a substrate. [Means for solving the problem]

[0009] In order to solve the above problem, the invention of claim 1 provides a heat treatment apparatus for heating a substrate by irradiating the substrate with light, the heat treatment apparatus comprising: a chamber for accommodating a substrate; a holder for holding the substrate within the chamber; a plurality of continuously lit lamps provided on one side of the chamber for irradiating light onto the substrate held by the holder; a plurality of detection units for detecting warpage of the substrate held by the holder; and a control unit for controlling intensities of the plurality of continuously lit lamps to eliminate the warpage of the substrate when warpage of the substrate is detected by the plurality of detection units. Each of the plurality of detection units includes a light projecting unit and a light receiving unit, the light projecting unit and the light receiving unit are installed at a height position within 2 mm from the upper surface of the substrate held by the holding unit, and the plurality of detection units include a light projecting unit and a light receiving unit that project and receive a laser beam that travels straight in the horizontal direction above the center of the substrate, and a light projecting unit and a light receiving unit that project and receive a laser beam that travels straight in the horizontal direction above the peripheral portion of the substrate. It is characterized by:

[0010] The invention of claim 2 is characterized in that, in the heat treatment device of the invention of claim 1, the control unit controls the intensity for each of the multiple sections obtained by dividing the light source area in which the multiple continuously lit lamps are arranged into multiple sections.

[0011] The invention of claim 3 is characterized in that, in the heat treatment apparatus of the invention of claim 2, when the multiple detection units detect that the substrate is warped convexly upward, the control unit reduces the strength of a central section among the multiple sections, and when the multiple detection units detect that the substrate is warped convexly downward, the control unit increases the strength of the central section.

[0013] In addition, claims 4 The invention is as follows: 3 The heat treatment apparatus according to any one of the above aspects of the present invention is characterized in that it further comprises a plurality of flash lamps provided on the other side of the chamber and configured to irradiate the substrate held by the holder with a flash of light.

[0014] In addition, claims 5 The present invention relates to a heat treatment method for heating a substrate by irradiating the substrate with light, the method comprising the steps of: irradiating light from a plurality of continuously lit lamps onto a substrate held by a holder in a chamber; and reducing warping of the substrate held by the holder. With multiple detectorsand a control step of controlling the intensities of the plurality of continuously lit lamps so as to eliminate the warping of the substrate when the warping of the substrate is detected in the detection step. Each of the plurality of detection units includes a light projecting unit and a light receiving unit, the light projecting unit and the light receiving unit are installed at a height position within 2 mm from the upper surface of the substrate held by the holding unit, and the plurality of detection units include a light projecting unit and a light receiving unit that project and receive a laser beam that travels straight in the horizontal direction above the center of the substrate, and a light projecting unit and a light receiving unit that project and receive a laser beam that travels straight in the horizontal direction above the peripheral portion of the substrate. It is characterized by:

[0015] Also, claims 6 The invention is as follows: 5 In the heat treatment method according to the present invention, the control step is characterized in that a light source area in which the plurality of continuously lit lamps are arranged is divided into a plurality of sections, and the intensity is controlled for each of the sections.

[0016] Also, claims 7 The invention is as follows: 6 In the heat treatment method according to the present invention, when it is detected in the detection process that the substrate is warped convexly upward, the strength of a central section among the plurality of sections is reduced in the control process, and when it is detected in the detection process that the substrate is warped convexly downward, the strength of the central section is increased in the control process.

[0017] Also, claims 8 The invention is as follows: 5 From claims 7 The heat treatment method according to any one of the above aspects of the present invention is characterized in that it further comprises, after the irradiation step, a flash light irradiation step of irradiating the substrate held by the holder with flash light from a plurality of flash lamps. Effect of the Invention

[0018] Claims 1 to 5 4 According to the invention, when warping of the substrate is detected by multiple detection units, the intensities of multiple continuously lit lamps are controlled to eliminate the warping of the substrate, thereby making it possible to correct the warping of the substrate.

[0019] In particular, claims 4According to the invention, the apparatus further includes a plurality of flash lamps that irradiate a flash of light onto the substrate held by the holding portion, and by irradiating the substrate after the warping has been corrected with a flash of light, cracks in the substrate can be prevented.

[0020] Claim 5 From claims 8 According to the invention, when warping of the substrate is detected in the detection process, the intensities of the multiple continuously lit lamps are controlled so as to eliminate the warping of the substrate, so that the warping of the substrate can be corrected.

[0021] In particular, claims 8 According to the invention, the method further includes a flash light irradiation process of irradiating the substrate held by the holding portion with flash light from a plurality of flash lamps, and by irradiating the substrate after correcting the warp with flash light, cracking of the substrate can be prevented. [Brief description of the drawings]

[0022] [Figure 1] 1 is a vertical cross-sectional view showing a configuration of a heat treatment apparatus according to the present invention. [Diagram 2] FIG. 2 is a perspective view showing the overall appearance of a holding portion. [Diagram 3] FIG. [Figure 4] FIG. 2 is a cross-sectional view of a susceptor. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 2 is a plan view showing an arrangement of a plurality of halogen lamps. [Figure 8] FIG. 2 is a side view of a detection unit and a susceptor. [Figure 9] FIG. 13 is a plan view showing a configuration example in which a plurality of detection units are arranged. [Figure 10] 2 is a flowchart showing a procedure of a processing operation in the heat treatment apparatus of FIG. [Figure 11] 10A and 10B are diagrams illustrating the intensity control of a halogen lamp when a semiconductor wafer is warped upwardly. [Figure 12] 10A and 10B are diagrams illustrating the intensity control of the halogen lamp when a semiconductor wafer is warped downward. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0024] Fig. 1 is a vertical cross-sectional view showing the 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 disk-shaped semiconductor wafer W as a substrate by irradiating the semiconductor wafer W with flash light. The size of the semiconductor wafer W to be treated is not particularly limited, but is, for example, φ300 mm or φ450 mm. In Fig. 1 and the subsequent figures, the dimensions and number of each part are exaggerated or simplified as necessary for ease of understanding.

[0025] The heat treatment apparatus 1 includes a chamber 6 that accommodates a semiconductor wafer W, a flash heating unit 5 that incorporates a plurality of flash lamps FL, and a halogen heating unit 4 that incorporates 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. The heat treatment apparatus 1 also includes, inside the chamber 6, a holding unit 7 that holds the semiconductor wafer W in a horizontal position, and a transfer mechanism 10 that transfers the semiconductor wafer W between the holding unit 7 and the outside of the apparatus. The heat treatment apparatus 1 also includes a control unit 3 that controls the respective operating mechanisms provided in the halogen heating unit 4, the flash heating unit 5, and the chamber 6 to perform heat treatment of the semiconductor wafer W.

[0026] The chamber 6 is configured by mounting quartz chamber windows on the top and bottom of a cylindrical chamber side portion 61. The chamber side portion 61 has a roughly cylindrical shape with openings at the top and bottom, with an upper chamber window 63 mounted and closed at the upper opening, and a lower chamber window 64 mounted and closed at the lower opening. The upper chamber window 63 constituting the ceiling of the chamber 6 is a disk-shaped member made of quartz, and functions as a quartz window that transmits the 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 disk-shaped member made of quartz, and functions as a quartz window that transmits the light from the halogen heating unit 4 into the chamber 6.

[0027] In addition, a reflective ring 68 is attached to the upper part of the inner wall surface of the chamber side part 61, and a reflective ring 69 is attached to the lower part. Both of the reflective rings 68, 69 are formed in an annular shape. The upper reflective ring 68 is attached by fitting it from the upper side of the chamber side part 61. On the other hand, the lower reflective ring 69 is attached by fitting it from the lower side of the chamber side part 61 and fastening it with screws (not shown). In other words, both of the reflective rings 68, 69 are detachably attached to the chamber side part 61. The inner space of the chamber 6, i.e., the space surrounded by the upper chamber window 63, the lower chamber window 64, the chamber side part 61, and the reflective rings 68, 69, is defined as a heat treatment space 65.

[0028] By mounting the reflecting rings 68, 69 on the chamber side portion 61, a recess 62 is formed on the inner wall surface of the chamber 6. That is, the recess 62 is formed by a central portion of the inner wall surface of the chamber side portion 61 where the reflecting rings 68, 69 are not mounted, the lower end surface of the reflecting ring 68, and the upper end surface of the reflecting ring 69. The recess 62 is formed in an annular shape along the horizontal direction on the inner wall surface of the chamber 6, and surrounds the holder 7 that holds the semiconductor wafer W. The chamber side portion 61 and the reflecting rings 68, 69 are formed from a metal material (e.g., stainless steel) that has excellent strength and heat resistance.

[0029] Further, a transfer opening (furnace port) 66 for carrying a semiconductor wafer W into and out of the chamber 6 is formed in the chamber side portion 61. The transfer opening 66 can be opened and closed by a gate valve 185. The transfer opening 66 is connected in communication with the outer circumferential surface of the recess 62. Therefore, when the gate valve 185 opens the transfer opening 66, the semiconductor wafer W can be carried into and out of the heat treatment space 65 through the transfer opening 66 and the recess 62. Furthermore, when the gate valve 185 closes the transfer opening 66, the heat treatment space 65 in the chamber 6 becomes an airtight space.

[0030] Further, a through hole 61a is formed in the chamber side 61. A radiation thermometer 20 is attached to the portion of the outer wall surface of the chamber side 61 where the through hole 61a is provided. The through hole 61a is a cylindrical hole for guiding infrared light radiated from the lower surface of a semiconductor wafer W held by a susceptor 74 described later to the radiation thermometer 20. The through hole 61a is provided at an incline with respect to the horizontal direction so that the axis of the through hole 61a intersects with the main surface of the semiconductor wafer W held by the susceptor 74. Thus, the radiation thermometer 20 is provided obliquely below the susceptor 74. 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 attached to the end of the through hole 61a facing the heat treatment space 65.

[0031] Further, a gas supply hole 81 is formed in the upper part of the inner wall of the chamber 6 to supply a processing gas to the heat treatment space 65. The gas supply hole 81 is formed at a position above the recessed portion 62, and may be provided in the reflecting 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 connected to a processing gas supply source 85. A valve 84 is inserted in the middle of the gas supply pipe 83. When the valve 84 is opened, the processing gas is supplied from the processing gas supply source 85 to the buffer space 82. The processing gas that has flowed into the buffer space 82 flows in a spreading manner in the buffer space 82, which has a smaller fluid resistance than the gas supply hole 81, and is supplied from the gas supply hole 81 to the heat treatment space 65. As the processing gas, for example, an inert gas such as nitrogen (N2), a reactive gas such as hydrogen (H2) or ammonia (NH3), or a mixed gas of these gases can be used (nitrogen gas in this embodiment).

[0032] On the other hand, a gas exhaust hole 86 is formed in the lower part of the inner wall of the chamber 6 to exhaust the gas in the heat treatment space 65. The gas exhaust hole 86 is formed at a position lower than the recessed portion 62, and may be provided in the reflecting ring 69. The gas exhaust hole 86 is connected to a gas exhaust pipe 88 through 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 an exhaust unit 190. A valve 89 is inserted in the middle of the gas exhaust pipe 88. When the valve 89 is opened, the gas in the heat treatment space 65 is exhausted from the gas exhaust hole 86 through the buffer space 87 to the gas exhaust pipe 88. The gas supply hole 81 and the gas exhaust hole 86 may be provided in a plurality of holes along the circumferential direction of the chamber 6, or may be slit-shaped. The process gas supply source 85 and the exhaust unit 190 may be mechanisms provided in the heat treatment apparatus 1, or may be utilities of a factory in which the heat treatment apparatus 1 is installed.

[0033] 2 is a perspective view showing the overall appearance of the holder 7. The holder 7 holds a semiconductor wafer W in the chamber 6. The holder 7 is configured to include a base ring 71, a connecting portion 72, and a susceptor 74. The base ring 71, the connecting portion 72, and the susceptor 74 are all made of quartz. That is, the entire holder 7 is made of quartz.

[0034] The base ring 71 is an arc-shaped quartz member with a portion missing from the annular shape. This missing portion is provided to prevent interference between the base ring 71 and a transfer arm 11 of the transfer mechanism 10, which will be described later. The base ring 71 is placed on the bottom surface of the recess 62, and is supported by the wall surface of the chamber 6 (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 annular shape. The connecting portions 72 are also quartz members, and are fixed to the base ring 71 by welding.

[0035] 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 cross-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 flat member made 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 planar size than the semiconductor wafer W.

[0036] A guide ring 76 is installed on the periphery 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 is a tapered surface that widens from the holding plate 75 upward. The guide ring 76 is made of quartz, similar to the holding plate 75. The guide ring 76 may be fused 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 integrated member.

[0037] The area of ​​the upper surface of the holding plate 75 inside the guide ring 76 is a flat holding surface 75a that holds the semiconductor wafer W. A plurality of substrate support pins 77 are provided on the holding surface 75a of the holding plate 75. In this embodiment, a total of 12 substrate support pins 77 are provided at 30° intervals along a circumference concentric with the outer circumferential circle of the holding surface 75a (the inner circumferential circle 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 is φ270 mm to φ280 mm (φ270 mm in this embodiment) if the diameter of the semiconductor wafer W is φ300 mm. Each substrate support pin 77 is made of quartz. The 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.

[0038] Returning to FIG. 2, four connecting parts 72 erected on the base ring 71 and the peripheral part 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 parts 72. The base ring 71 of the holding part 7 is supported on the wall surface of the chamber 6, and the holding part 7 is attached to the chamber 6. When the holding part 7 is attached to the chamber 6, the holding plate 75 of the susceptor 74 is in a horizontal position (a position 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.

[0039] The semiconductor wafer W carried into the chamber 6 is placed and held in a horizontal position on the susceptor 74 of the holder 7 attached to the chamber 6. At this time, the semiconductor wafer W is supported by twelve substrate support pins 77 standing on a holding plate 75 and held on 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. The heights of the twelve 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, so that the twelve substrate support pins 77 can support the semiconductor wafer W in a horizontal position.

[0040] Furthermore, the semiconductor wafer W is supported by a 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 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 shifting in the horizontal direction.

[0041] 2 and 3, an opening 78 is formed in the holding plate 75 of the susceptor 74, penetrating vertically. The opening 78 is provided so that the radiation thermometer 20 can receive radiation light (infrared light) emitted from the underside of the semiconductor wafer W. That is, the radiation thermometer 20 receives the light emitted from the underside of the semiconductor wafer W through the opening 78 and a transparent window 21 attached to the through hole 61a of the chamber side part 61, and measures the temperature of the semiconductor wafer W. Furthermore, 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 to transfer the semiconductor wafer W.

[0042] 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 arms 11 are formed in an arc shape that is aligned with the generally annular recess 62. Two lift pins 12 are provided upright on each of the transfer arms 11. The transfer arms 11 and the lift pins 12 are made of quartz. Each transfer arm 11 is rotatable by a horizontal movement mechanism 13. The horizontal movement mechanism 13 horizontally moves the pair of transfer arms 11 between a transfer operation position (solid line position in FIG. 5) where the semiconductor wafer W is transferred to the holder 7 and a retracted position (double-dashed line position in FIG. 5) where the pair of transfer arms 11 do not overlap the semiconductor wafer W held by the holder 7 in a plan view. The horizontal movement mechanism 13 may be a mechanism that rotates each transfer arm 11 using an individual motor, or a mechanism that uses a link mechanism to rotate a pair of transfer arms 11 in unison using a single motor.

[0043] The pair of transfer arms 11 are raised and lowered together with the horizontal movement mechanism 13 by the lifting mechanism 14. When the lifting mechanism 14 raises the pair of transfer arms 11 to the transfer operation position, the 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 ends of the lift pins 12 protrude from the upper surface of the susceptor 74. On the other hand, when the lifting mechanism 14 lowers the pair of transfer arms 11 to the transfer operation position to remove the lift pins 12 from the through holes 79, and the horizontal movement mechanism 13 moves the pair of transfer arms 11 to open them, 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 holder 7. Since the base ring 71 is placed on the bottom surface of the recess 62, the retracted position of the transfer arms 11 is inside the recess 62. In addition, an exhaust mechanism (not shown) is provided near the location where the drive part of the transfer mechanism 10 (horizontal movement mechanism 13 and lifting mechanism 14) is located, and is configured to exhaust the atmosphere around the drive part of the transfer mechanism 10 to the outside of the chamber 6.

[0044] Returning to FIG. 1, the flash heating unit 5 provided above the chamber 6 is configured to include a light source consisting of multiple (30 in this embodiment) xenon flash lamps FL inside a housing 51, and a reflector 52 provided to cover the light source from above. A lamp light emission window 53 is attached to the bottom of the housing 51 of the flash heating unit 5. The lamp light emission window 53 forming the floor of the flash heating unit 5 is a plate-shaped quartz window made of quartz. By installing the flash heating unit 5 above the chamber 6, the lamp light emission window 53 faces the upper chamber window 63. The flash lamps FL irradiate flash light from above the chamber 6 through the lamp light emission window 53 and the upper chamber window 63 into the heat treatment space 65.

[0045] The multiple flash lamps FL are each a rod-shaped lamp having a long cylindrical shape, and are arranged in a plane such that their respective longitudinal directions are parallel to each other along the main surface of the semiconductor wafer W held by the holder 7 (i.e., along the horizontal direction). Therefore, the plane formed by the arrangement of the flash lamps FL is also a horizontal plane. The area in which the multiple flash lamps FL are arranged is larger than the planar size of the semiconductor wafer W.

[0046] The xenon flash lamp FL comprises a cylindrical glass tube (discharge tube) filled with xenon gas and having an anode and a cathode connected to a capacitor at both ends, and a trigger electrode attached to the outer periphery of the glass tube. Since xenon gas is an electrical insulator, electricity does not flow through the glass tube under normal conditions even if an electric charge is stored in the capacitor. However, when a high voltage is applied to the trigger electrode to break down the insulation, the electricity stored in the capacitor flows instantly through the glass tube, and light is emitted by the excitation of the xenon atoms or molecules at that time. In such a xenon flash lamp FL, the electrostatic energy stored in the capacitor in advance is converted into an extremely short light pulse of 0.1 to 100 milliseconds, so that it has the characteristic of being able to irradiate extremely strong light compared to a light source that is continuously lit such as a halogen lamp HL. In other words, the flash lamp FL is a pulsed light emitting lamp that emits light instantaneously for an extremely short time of less than one second. The light emission time of the flash lamps FL can be adjusted by the coil constant of the lamp power supply that supplies power to the flash lamps FL.

[0047] Moreover, the reflector 52 is provided above the multiple flash lamps FL so as to cover them entirely. The basic function of the reflector 52 is to reflect the flash light emitted from the multiple flash lamps FL toward the heat treatment space 65. The reflector 52 is made of an aluminum alloy plate, and its surface (the surface facing the flash lamps FL) is roughened by blasting.

[0048] The halogen heating unit 4 provided below the chamber 6 has a plurality of halogen lamps HL (40 in this embodiment) built inside the housing 41. The halogen heating unit 4 irradiates light from below the chamber 6 through a lower chamber window 64 into a heat treatment space 65 using the plurality of halogen lamps HL to heat the semiconductor wafer W held by the holder 7.

[0049] FIG. 7 is a plan view showing the arrangement of a plurality of halogen lamps HL. 40 halogen lamps HL are arranged in two tiers, upper and lower. 20 halogen lamps HL are arranged in the upper tier close to the holder 7, and 20 halogen lamps HL are also arranged in the lower tier farther from the holder 7 than the upper tier. Each halogen lamp HL is a rod-shaped lamp having a long cylindrical shape. The 20 halogen lamps HL in both the upper and lower tiers are arranged so that their longitudinal directions are parallel to each other along the main surface of the semiconductor wafer W held by the holder 7 (i.e., along the horizontal direction). Therefore, the plane formed by the arrangement of the halogen lamps HL in both the upper and lower tiers is a horizontal plane.

[0050] 7, the halogen lamps HL are arranged at a higher density in the region facing the periphery of the semiconductor wafer W held by the holder 7 in both the upper and lower tiers than in the region facing the center of the semiconductor wafer W. That is, in both the upper and lower tiers, the arrangement pitch of the halogen lamps HL is shorter in the periphery of the lamp arrangement than in the center. This makes it possible to irradiate a greater amount of light to the periphery of the semiconductor wafer W, which is prone to temperature drop during heating by light irradiation from the halogen heating unit 4.

[0051] The lamp group consisting of the halogen lamps HL in the upper row and the lamp group consisting of the halogen lamps HL in the lower row are arranged to intersect in a lattice pattern. That is, a total of 40 halogen lamps HL are arranged so that the longitudinal direction of the 20 halogen lamps HL arranged in the upper row and the longitudinal direction of the 20 halogen lamps HL arranged in the lower row are perpendicular to each other.

[0052] The halogen lamp HL is a filament type light source that emits light by passing electricity through a filament disposed inside a glass tube, which becomes incandescent. A gas consisting of an inert gas such as nitrogen or argon with a small amount of halogen elements (iodine, bromine, etc.) is sealed inside the glass tube. By introducing halogen elements, it is possible to set the temperature of the filament at a high temperature while suppressing filament breakage. Therefore, the halogen lamp HL has the characteristics of having a longer life than a normal incandescent light bulb and being able to continuously irradiate strong light. In other words, the halogen lamp HL is a continuous lighting lamp that emits light continuously for at least one second or more. In addition, 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 semiconductor wafer W above is excellent.

[0053] The light source area in which a plurality of halogen lamps HL are arranged is divided into a plurality of sections. In this embodiment, as shown in Fig. 7, the light source area in which 40 halogen lamps HL are arranged is divided into nine sections AP1 to AP9 separated by dotted lines. The control unit 3 can control the intensity of the emitted light for each section of the light source area. For example, when increasing the intensity of the emitted light from the central section AP5, the control unit 3 increases the output of the halogen lamps HL arranged at the center of each of the upper lamp group and the lower lamp group.

[0054] Also, a reflector 43 is provided below the two-tiered halogen lamps HL within the housing 41 of the halogen heating unit 4 (FIG. 1). The reflector 43 reflects the light emitted from the multiple halogen lamps HL toward the heat treatment space 65.

[0055] The control unit 3 controls the various operating mechanisms provided in the heat treatment device 1. The hardware configuration of the control unit 3 is similar to that of a general computer. That is, the control unit 3 includes a CPU, which is a circuit that performs various arithmetic processing, a ROM, which is a read-only memory that stores basic programs, a RAM, which is a readable and writable memory that stores various information, and a magnetic disk that stores control software, data, and the like. The CPU of the control unit 3 executes a predetermined processing program, and thereby the processing in the heat treatment device 1 proceeds.

[0056] As shown in FIG. 1, the chamber 6 is provided with a detector 91 for detecting warpage of the semiconductor wafer W held by the holder 7. FIG. 8 is a side view of the detector 91 and the susceptor 74. FIG. 9 is a plan view showing a configuration example in which a plurality of detectors 91 are arranged. In this embodiment, five detectors 91 are arranged. Each of the five detectors 91 is a light-emitting / receiving sensor composed of a pair of a light-emitting section DL and a light-receiving section RL. The five light-emitting sections DL and the five light-receiving sections RL are installed on the wall surface of the chamber 6. The pair of light-emitting section DL and light-receiving section RL constituting one detector 91 are provided so as to face each other with the susceptor 74 in between. The distance Δd between each light-emitting section DL and each light-receiving section RL and the upper surface of the semiconductor wafer W held by the susceptor 74 is 2 mm or less. That is, each light-emitting section DL and each light-receiving section RL is installed at a height position within 2 mm from the upper surface of the semiconductor wafer W held by the holder 7. For example, a semiconductor device such as a memory may warp by about 1 mm due to having more than 100 layers. Therefore, it is preferable to install the light projecting unit DL and the light receiving unit RL at a height position within about 2 mm from the upper surface of the semiconductor wafer W.

[0057] Laser light is projected and received between a pair of light projecting unit DL and light receiving unit RL constituting one detection unit 91. That is, the laser light emitted horizontally from the light projecting unit DL travels straight in parallel with the upper surface of the semiconductor wafer W held in a horizontal position on the susceptor 74 and is received by the light receiving unit RL. When the semiconductor wafer W held on the susceptor 74 is not warped, the laser light emitted from the light projecting unit DL is received by the corresponding light receiving unit RL without being blocked. Hereinafter, a state in which the laser light emitted from the light projecting unit DL is received by the corresponding light receiving unit RL without being blocked is referred to as the detection unit 91 not detecting warpage. On the other hand, when the semiconductor wafer W held on the susceptor 74 is warped, the laser light emitted from the light projecting unit DL is blocked by the semiconductor wafer W, and the corresponding light receiving unit RL cannot receive the laser light. Hereinafter, a state in which the laser light emitted from the light projecting portion DL is blocked and not received by the corresponding light receiving portion RL will be referred to as the detection portion 91 detecting a warp.

[0058] When none of the five detectors 91 detects warpage, the control unit 3 determines that no warpage has occurred in the semiconductor wafer W held by the susceptor 74. Conversely, when at least one of the five detectors 91 detects warpage, the control unit 3 determines that warpage has occurred in the semiconductor wafer W held by the susceptor 74.

[0059] In this embodiment, five detectors 91 are provided at different positions. Therefore, the five detectors 91 can detect not only whether the semiconductor wafer W is warped, but also the type of warp of the semiconductor wafer W. Specifically, the five detectors 91 can detect the direction of warp of the semiconductor wafer W (whether the warp is upwardly convex or downwardly convex), the amount of warp, and the position of the warp. For example, when the detector 91 that measures the vicinity of the center of the semiconductor wafer W detects warp, and the detector 91 that measures the peripheral portion does not detect warp, the semiconductor wafer W is determined to be warped upwardly convex. Conversely, when the detector 91 that measures the peripheral portion of the semiconductor wafer W detects warp, and the detector 91 that measures the vicinity of the center does not detect warp, the semiconductor wafer W is determined to be warped downwardly convex.

[0060] In addition to the above configuration, the heat treatment apparatus 1 is provided with various cooling structures to prevent an excessive temperature rise in the halogen heating unit 4, the flash heating unit 5, and the chamber 6 due to the thermal energy generated from the halogen lamps HL and the flash lamps FL during the heat treatment of the semiconductor wafer W. For example, a water-cooling pipe (not shown) is provided in the wall of the chamber 6. The halogen heating unit 4 and the flash heating unit 5 are also of an air-cooled structure that forms a gas flow inside to remove 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.

[0061] Next, a description will be given of the processing operation in the above-mentioned heat treatment apparatus 1. Fig. 10 is a flow chart showing the procedure of the processing operation in the heat treatment apparatus 1. The processing procedure in the heat treatment apparatus 1 described below progresses as a result of the control unit 3 controlling each operating mechanism of the heat treatment apparatus 1.

[0062] First, prior to processing of the semiconductor wafer W, the valve 84 for supplying air is opened, and the exhaust valve 89 is also opened to start supplying and exhausting air to and from the chamber 6. When the valve 84 is opened, nitrogen gas is supplied to the heat treatment space 65 from the gas supply hole 81. When the valve 89 is opened, the gas in the chamber 6 is exhausted from the gas exhaust hole 86. As a result, the nitrogen gas supplied from the upper part of the heat treatment space 65 in the chamber 6 flows downward and is exhausted from the lower part of the heat treatment space 65.

[0063] Next, the gate valve 185 is opened to open the transport opening 66, and a semiconductor wafer W to be processed is carried into the heat treatment space 65 in the chamber 6 through the transport opening 66 by a transport robot outside the apparatus (step S1). The semiconductor wafer W to be processed is a disk-shaped silicon (Si) semiconductor substrate. There is a risk that the atmosphere outside the apparatus will be drawn in when the semiconductor wafer W is carried in, but since nitrogen gas is continuously supplied to the chamber 6, the nitrogen gas flows out from the transport opening 66, making it possible to minimize the drawing in of such external atmosphere.

[0064] The semiconductor wafer W carried in by the transport robot advances to a position directly above the holder 7 and stops there. Then, the pair of transfer arms 11 of the transfer mechanism 10 move horizontally from the retreated position to the transfer operation position and rise, causing the lift pins 12 to pass through the through holes 79 and protrude from the upper surface of the holding plate 75 of the susceptor 74 to receive the semiconductor wafer W. At this time, the lift pins 12 rise to a position above the upper ends of the substrate support pins 77.

[0065] After the semiconductor wafer W is placed on the lift pins 12, the transport robot leaves the heat treatment space 65, and the transport opening 66 is closed by the gate valve 185. Then, the pair of transfer arms 11 descend, so that the semiconductor wafer W is transferred from the transfer mechanism 10 to the susceptor 74 of the holder 7 and held from below in a horizontal position. The semiconductor wafer W is supported by a plurality of substrate support pins 77 erected on the holding plate 75 and held by the susceptor 74. The semiconductor wafer W is held by the holder 7 with its front surface facing up. 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 descend to below the susceptor 74 are retreated to a retreat position, that is, inside the recess 62, by the horizontal movement mechanism 13.

[0066] After the semiconductor wafer W is held from below in a horizontal position by the susceptor 74 of the holder 7 made of quartz, the 40 halogen lamps HL of the halogen heating unit 4 are turned on all at once to start preheating (assisted heating) (step S2). The halogen lamps HL irradiate the semiconductor wafer W held by the holder with light to preheat the semiconductor wafer W. The halogen light emitted from the halogen lamps HL is transmitted through the lower chamber window 64 and the susceptor 74 made of quartz and irradiated onto the underside of the semiconductor wafer W. The semiconductor wafer W is preheated by being irradiated with light from the halogen lamps HL, and its temperature rises. Note that the transfer arm 11 of the transfer mechanism 10 is retracted inside the recess 62 and does not interfere with heating by the halogen lamps HL.

[0067] The temperature of the semiconductor wafer W, which is heated by the light irradiation from the halogen lamps HL, is measured by a radiation thermometer 20. 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 lamps HL while monitoring whether the temperature of the semiconductor wafer W, which is heated by the light irradiation from the halogen lamps HL, has reached a predetermined preheating temperature T1. That is, the control unit 3 feedback-controls the output of the halogen lamps 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.

[0068] 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 lamps HL to maintain the temperature of the semiconductor wafer W at approximately the preheating temperature T1.

[0069] By performing such preheating with the halogen lamps HL, the temperature of the entire semiconductor wafer W is uniformly raised to the preheating temperature T1. During the preheating stage with the halogen lamps HL, the temperature of the peripheral portion of the semiconductor wafer W, where heat dissipation is more likely to occur, tends to be lower than that of the central portion, but the arrangement density of the halogen lamps HL in the halogen heating unit 4 is higher in the region facing the peripheral portion than in the region facing the central portion of the semiconductor wafer W. As a result, a greater amount of light is irradiated to the peripheral portion of the semiconductor wafer W, where heat dissipation is more likely to occur, and the in-plane temperature distribution of the semiconductor wafer W during the preheating stage can be made uniform.

[0070] When the semiconductor wafer W is heated by the light irradiation from the halogen lamps HL, the semiconductor wafer W may be warped. If the semiconductor wafer W is irradiated with flash light while the warped state is maintained, the semiconductor wafer W may crack. For this reason, in this embodiment, the warp generated in the semiconductor wafer W is corrected as follows. Typically, the susceptor 74 is heated before the semiconductor wafer W is loaded into the chamber 6 in order to make the temperature history of the semiconductor wafers W processed continuously uniform. Therefore, before the light irradiation from the halogen lamps HL is started, the semiconductor wafer W may be warped due to the thermal effect of the susceptor 74 simply by being held on the heated susceptor 74. The warp of the semiconductor wafer W to be corrected as described below includes not only warp caused by heating due to light irradiation from the halogen lamps HL, but also warp generated before the halogen lamps HL are turned on.

[0071] After the semiconductor wafer W is held by the susceptor 74, the warpage of the semiconductor wafer W is continuously monitored by the multiple detectors 91 (five in this embodiment) (step S3). If none of the multiple detectors 91 detects warpage, it is determined that no warpage has occurred in the semiconductor wafer W, and the process proceeds from step S3 to step S5, where flash light irradiation is performed. On the other hand, if at least one of the multiple detectors 91 detects warpage, it is determined that warpage has occurred in the semiconductor wafer W, and the process proceeds from step S3 to step S4, where a warpage correction process is performed.

[0072] When the multiple detectors 91 detect the warpage of the semiconductor wafer W, the control unit 3 controls the radiated light intensity of the multiple halogen lamps HL based on the information on the warpage of the semiconductor wafer W from the multiple detectors 91 so as to eliminate the warpage of the semiconductor wafer W. In this case, the control unit 3 controls the intensity of the radiated light for each of the nine sections AP1 to AP9 into which the light source area in which the 40 halogen lamps HL are arranged is divided. Specifically, for example, as shown in FIG. 11, when the multiple detectors 91 detect that the semiconductor wafer W is warped upwardly, the control unit 3 reduces the intensity of the radiated light from the central section AP5 of the nine sections AP1 to AP9. As a result, the illuminance of the light irradiated to the center of the semiconductor wafer W is reduced, and the central section is heated relatively weakly, thereby correcting the upwardly convex warpage of the semiconductor wafer W.

[0073] 12, when the multiple detectors 91 detect that the semiconductor wafer W is warped in a convex downward direction, the controller 3 increases the intensity of the emitted light from the central section AP5 of the nine sections AP1 to AP9. This increases the illuminance of the light irradiated to the central section of the semiconductor wafer W, and the central section is heated relatively more strongly, thereby correcting the downward convex warp of the semiconductor wafer W.

[0074] After the warpage of the semiconductor wafer W is corrected by adjusting the radiated light intensity of the multiple halogen lamps HL and the semiconductor wafer W is placed in a flat horizontal position, the flash lamps FL of the flash heating unit 5 irradiate the surface of the semiconductor wafer W held on the susceptor 74 with flash light (step S5). At this time, part of the flash light radiated from the flash lamps FL heads directly into the chamber 6, and the other part is reflected by the reflector 52 before heading into the chamber 6, and the semiconductor wafer W is flash-heated by the irradiation of these flash lights.

[0075] Flash heating is performed by irradiating a flash of light (flash of light) from the flash lamps FL, and can raise the surface temperature of the semiconductor wafer W in a short time. That is, the flash of light irradiated from the flash lamps FL is an extremely short and strong flash of light with an irradiation time of about 0.1 to 100 milliseconds, in which electrostatic energy previously stored in a capacitor is converted into an extremely short light pulse. The surface temperature of the semiconductor wafer W flash-heated by the irradiation of the flash light from the flash lamps FL instantaneously rises to a processing temperature T2 of 1000°C or higher and then rapidly drops.

[0076] After the flash heating process is completed, the halogen lamps HL are turned off after a predetermined time has elapsed. This causes the temperature of the semiconductor wafer W to rapidly drop from the preheating temperature T1. The temperature of the semiconductor wafer W during the temperature drop 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 of the radiation thermometer 20. Then, after the temperature of the semiconductor wafer W has dropped to a predetermined temperature or lower, the pair of transfer arms 11 of the transfer mechanism 10 again move horizontally from the retreat position to the transfer operation position and rise, so that the lift pins 12 protrude from the upper surface of the susceptor 74 and receive the semiconductor wafer W after the heat treatment from the susceptor 74. Next, the transfer opening 66 that was closed by the gate valve 185 is opened, and the semiconductor wafer W placed on the lift pins 12 is carried out of the chamber 6 by a transfer robot outside the apparatus (step S6), and the heat treatment of the semiconductor wafer W is completed.

[0077] In this embodiment, the warpage of the semiconductor wafer W held on the susceptor 74 is detected by a plurality of detectors 91. Then, when warpage of the semiconductor wafer W is detected, the controller 3 controls the radiant light intensity of the plurality of halogen lamps HL so as to eliminate the warpage. This makes it possible to correct the warpage of the semiconductor wafer W even if the warpage occurs in the semiconductor wafer W due to thermal influence. By irradiating the surface of the semiconductor wafer W whose warpage has been corrected with flash light from the flash lamps FL, it is possible to prevent the semiconductor wafer W from cracking when it is suddenly heated.

[0078] Although the embodiment of the present invention has been described above, various modifications of the present invention are possible without departing from the spirit of the present invention. For example, in the above embodiment, the detection unit 91 is a light projecting and receiving sensor composed of a pair of a light projecting unit DL and a light receiving unit RL, but the present invention is not limited to this, and the detection unit 91 may be a laser displacement meter. Alternatively, the detection unit 91 may be a device that detects the warpage of the semiconductor wafer W using reflected laser light or laser interference. Furthermore, a camera may be used as the detection unit 91. In other words, various known mechanisms that can detect the warpage of the semiconductor wafer W can be adopted as the detection unit 91.

[0079] Also, in the above embodiment, five detectors 91 are provided in the heat treatment apparatus 1, but this is not limiting, and the number of detectors 91 may be two or more. If it is only necessary to detect whether or not the semiconductor wafer W is warped, one detector 91 is sufficient, but in order to detect the type of warp in the semiconductor wafer W and control the intensities of the multiple halogen lamps HL based on that, two or more detectors 91 are required. For this reason, the number of detectors 91 is set to two or more.

[0080] The greater the number of the detection units 91, the more precisely it becomes possible to detect the warpage direction, warpage amount, and warpage position of the semiconductor wafer W. When the number of the detection units 91 is large, an artificial intelligence (AI) function may be implemented in the control unit 3, and the detection results of the multiple detection units 91 may be analyzed using the AI ​​to control the intensity of the multiple halogen lamps HL. In this case, a model previously constructed using machine learning is applied to determine optimal parameters for controlling the intensity of the halogen lamps HL. Also, when a camera is used as the detection unit 91, it is preferable to have the AI ​​learn various image parameters to determine optimal parameters for controlling the intensity of the halogen lamps HL.

[0081] In the above embodiment, the flash heating unit 5 is provided with 30 flash lamps FL, but this is not limited to this and the number of flash lamps FL can be any number. The flash lamps FL are not limited to xenon flash lamps and may be krypton flash lamps. The number of halogen lamps HL provided in the halogen heating unit 4 is not limited to 40 and can be any number.

[0082] In the above embodiment, the heat treatment is performed by using a filament type halogen lamp HL as a continuously lit lamp that emits light continuously for one second or more, but the present invention is not limited to this, and the heat treatment may be performed by using a discharge type arc lamp (e.g., a xenon arc lamp) or an LED lamp as a continuously lit lamp instead of the halogen lamp HL. In this case, when warping of the semiconductor wafer W is detected, the intensity of the multiple continuously lit lamps is controlled. [Explanation of symbols]

[0083] 1 Heat treatment equipment 3. Control Unit 4 Halogen heating section 5 Flash heating section 6 Chambers 7 Holding part 10 Transfer mechanism 20 Radiation thermometer 65 Heat Treatment Space 74 Susceptor 91 Detection unit DL Light Projector RL light receiving section FL Flash lamp HL Halogen Lamp W Semiconductor wafer

Claims

1. A heat treatment apparatus for heating a substrate by irradiating the substrate with light, comprising: A chamber for housing a substrate; a holder that holds the substrate in the chamber; a plurality of continuously lit lamps provided on one side of the chamber and configured to irradiate light onto the substrate held by the holder; a plurality of detectors for detecting warpage of the substrate held by the holder; a control unit that controls intensities of the plurality of continuously lit lamps so as to eliminate the warping of the substrate when the warping of the substrate is detected by the plurality of detection units; Equipped with Each of the plurality of detection units includes a light projecting unit and a light receiving unit, the light-projecting unit and the light-receiving unit are disposed at a height position within 2 mm from an upper surface of the substrate held by the holding unit, The heat treatment apparatus is characterized in that the multiple detection units include a light-projecting unit and a light-receiving unit that project and receive laser light that travels straight horizontally above the center of the substrate, and a light-projecting unit and a light-receiving unit that project and receive laser light that travels straight horizontally above the peripheral portion of the substrate.

2. 2. The heat treatment apparatus according to claim 1, The heat treatment apparatus according to claim 1, wherein the control unit controls the intensity of each of a plurality of sections obtained by dividing a light source area in which the plurality of continuously lit lamps are arranged into a plurality of sections.

3. 3. The heat treatment apparatus according to claim 2, When the plurality of detection units detect that the substrate is warped upwardly, the control unit reduces the strength of a central section among the plurality of sections, and 4. The heat treatment apparatus according to claim 1, wherein when the plurality of detection units detect that the substrate is warped convexly downward, the control unit increases a strength of the central section.

4. 4. The heat treatment apparatus according to claim 1, The heat treatment apparatus further comprises a plurality of flash lamps provided on the other side of the chamber for irradiating the substrate held by the holder with a flash of light.

5. 1. A heat treatment method for heating a substrate by irradiating the substrate with light, comprising the steps of: an irradiation step of irradiating light from a plurality of continuously lit lamps onto the substrate held by a holder in a chamber; a detection step of detecting warpage of the substrate held by the holding unit using a plurality of detection units; a control step of controlling intensities of the plurality of continuously lit lamps so as to eliminate the warping of the substrate when the warping of the substrate is detected in the detection step; Equipped with Each of the plurality of detection units includes a light projecting unit and a light receiving unit, the light-projecting unit and the light-receiving unit are disposed at a height position within 2 mm from an upper surface of the substrate held by the holding unit, A heat treatment method characterized in that the multiple detection units include a light-projecting unit and a light-receiving unit that project and receive laser light that travels straight in a horizontal direction above the center of the substrate, and a light-projecting unit and a light-receiving unit that project and receive laser light that travels straight in a horizontal direction above the peripheral portion of the substrate.

6. The heat treatment method according to claim 5, The heat treatment method is characterized in that in the control step, a light source area in which the plurality of continuously lit lamps are arranged is divided into a plurality of sections, and intensity is controlled for each of the sections.

7. The heat treatment method according to claim 6, When it is detected in the detection step that the substrate is warped upwardly, the control step reduces the strength of a central section among the plurality of sections, A heat treatment method, characterized in that, when the detection step detects that the substrate is warped convexly downward, the control step increases the strength of the central section.

8. The heat treatment method according to any one of claims 5 to 7, The heat treatment method further comprises, after the irradiation step, a flash light irradiation step of irradiating the substrate held by the holder with flash lights from a plurality of flash lamps.

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