Heat treatment apparatus and heat treatment method

Abstract

The present invention provides a heat treatment apparatus and a heat treatment method that accelerate the cooling rate of a substrate after heat treatment. [Solution] The heat treatment apparatus 2 heats a semiconductor wafer W by irradiating the semiconductor wafer W with light. The heat treatment apparatus 2 includes a first flash light irradiation unit that irradiates the semiconductor wafer W with flash light to raise the surface of the semiconductor wafer W from room temperature to a preheating temperature, and a second flash light irradiation unit that irradiates the semiconductor wafer W, which has been raised to the preheating temperature, with flash light to raise the surface of the semiconductor wafer W to a processing temperature higher than the preheating temperature. Since both raising the temperature to the preheating temperature and raising the temperature to the processing temperature are done by flash light irradiation, the temperature of the back surface of the semiconductor wafer W hardly rises, and after flash light irradiation, a rapid heat conduction occurs from the front surface to the back surface of the semiconductor wafer W, which can speed up the rate of cooling of the semiconductor wafer W after heat treatment.

Description

Technical Field

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

Background Art

[0002] In the manufacturing process of semiconductor devices, flash lamp annealing (FLA) for heating a semiconductor wafer in an extremely short time has attracted attention. Flash lamp annealing is a heat treatment technique that uses a xenon flash lamp (hereinafter simply referred to as a "flash lamp" when referring to a xenon flash lamp) to irradiate flash light onto the surface of a semiconductor wafer, thereby raising the temperature of only the surface of the semiconductor wafer extremely rapidly (in several milliseconds or less).

[0003] The emission spectral distribution of a xenon flash lamp is from the ultraviolet region to the near infrared region, with a shorter wavelength than that of a conventional halogen lamp, and it almost coincides with the fundamental absorption band of a silicon semiconductor wafer. Therefore, when flash light is irradiated from a xenon flash lamp onto a semiconductor wafer, there is little transmitted light and the semiconductor wafer can be rapidly heated. Also, it has been found that if flash light is irradiated for an extremely short time of several milliseconds or less, only the vicinity of the surface of the semiconductor wafer can be selectively heated.

[0004] Such flash lamp annealing is used for processes that require heating in an extremely short time, for example, typically for activating impurities implanted in a semiconductor wafer. If flash light is irradiated from a flash lamp onto the surface of a semiconductor wafer into which impurities have been implanted by ion implantation, the temperature of the surface of the semiconductor wafer can be raised to the activation temperature in an extremely short time, and only impurity activation can be performed without deeply diffusing the impurities.

[0005] In typical flash lamp annealing systems, light from a halogen lamp is irradiated onto the back surface of a semiconductor wafer to preheat it to a certain temperature, and then flash light is irradiated onto the front surface of the semiconductor wafer to raise the temperature to the desired processing temperature and activate impurities.

[0006] Regarding apparatuses that utilize such flash lamp annealing, Patent Document 1 discloses an apparatus in which a cooling gas is supplied into the chamber after the flash heating process is completed. According to the apparatus disclosed in Patent Document 1, the relatively high temperature of the semiconductor wafer immediately after flash heating is cooled by supplying the cooling gas into the chamber.

[0007] Furthermore, regarding other devices that utilize flash lamp annealing, Patent Document 2 discloses a device that can vary the distance between a semiconductor wafer and a susceptor. In the device disclosed in Patent Document 2, the distance between the substrate and the plate-like member is set to a first interval during the heating process of the substrate supported by the support, and the distance between the substrate and the plate-like member is controlled to a second interval during the heat retention process in which the substrate is maintained at a target temperature. According to the device described in Patent Document 2, the controllability of the substrate temperature during light irradiation heating is improved. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2021-044372 [Patent Document 2] Japanese Patent Publication No. 2014-175630 [Overview of the project] [Problems that the invention aims to solve]

[0009] In recent years, there has been a need to prevent the deactivation of impurities activated by heat treatment by accelerating the cooling rate of substrates after heat treatment. However, the technologies disclosed in Patent Documents 1 and 2 have made it difficult to achieve the cooling rate required in recent years.

[0010] The present invention has been made in view of the above problems, and aims to provide a heat treatment apparatus and a heat treatment method that accelerate the cooling rate of a substrate after heat treatment. [Means for solving the problem]

[0011] To solve the above problems, the invention of claim 1 is a heat treatment apparatus for heating a substrate by irradiating the substrate with light, comprising: a chamber for housing the substrate; a holding part for holding the substrate within the chamber; a first flash light irradiation part for irradiating the substrate held by the holding part with flash light to raise the substrate from room temperature to a preheating temperature; and a second flash light irradiation part for irradiating the substrate, which has been raised to the preheating temperature, with flash light to raise the substrate to a processing temperature higher than the preheating temperature.

[0012] Furthermore, the invention of claim 2 is characterized in that, in the heat treatment apparatus described in claim 1, the flash light irradiation time of the first flash light irradiation unit and the second flash light irradiation unit is 0.1 milliseconds or more and 100 milliseconds or less.

[0013] Furthermore, the invention of claim 3 is characterized in that, in the heat treatment apparatus described in claim 1 or claim 2, the interval between the emission of light from the first flash light irradiation unit and the emission of light from the second flash light irradiation unit is within 1 second.

[0014] Furthermore, the invention of claim 4 is a heat treatment method for heating a substrate by irradiating the substrate with light, comprising: a first flash light irradiation step of irradiating the substrate, which is held by a holding part in a chamber containing the substrate, with a first flash light to raise the temperature of the substrate from room temperature to a preheating temperature; and a second flash light irradiation step of irradiating the substrate, which has been raised to the preheating temperature, with a second flash light to raise the temperature of the substrate to a processing temperature higher than the preheating temperature.

[0015] Furthermore, the invention of claim 5 is characterized in that, in the heat treatment method described in claim 4, the flash light irradiation time in the first flash light irradiation step and the second flash light irradiation step is 0.1 milliseconds or more and 100 milliseconds or less.

[0016] Furthermore, the invention of claim 6 is characterized in that, in the heat treatment method described in claim 4 or claim 5, the time between the completion of the first flash light irradiation step and the start of the second flash light irradiation step is within 1 second. [Effects of the Invention]

[0017] According to the invention of claims 1 to 3, the device includes a first flash light irradiation unit that irradiates the substrate held in the holding unit with flash light to raise the temperature of the substrate from room temperature to a preheating temperature, and a second flash light irradiation unit that irradiates the substrate, which has been raised to the preheating temperature, with flash light to raise the temperature of the substrate to a processing temperature higher than the preheating temperature. As a result, only a desired depth region from the surface of the substrate can be raised to the processing temperature. This reduces the thermal budget and speeds up the cooling rate of the substrate after heat treatment, and prevents the diffusion of impurities injected into the substrate.

[0018] According to the inventions of Claims 4 to 6, since it includes a first flash light irradiation step of raising the temperature of the substrate to the preliminary heating temperature and a second flash light irradiation step of raising the temperature of the substrate to a processing temperature higher than the preliminary heating temperature, it is possible to raise the temperature of only a desired depth region from the surface of the substrate to the processing temperature. Thereby, the thermal budget can be reduced, the temperature drop rate of the substrate after the heat treatment can be increased, and the diffusion of impurities implanted into the substrate can be prevented.

Brief Description of the Drawings

[0019] [Figure 1] It is a longitudinal sectional view showing the configuration of the heat treatment apparatus according to the present invention. [Figure 2] It is a perspective view showing the overall external appearance of the holding part. [Figure 3] It is a plan view of the susceptor. [Figure 4] It is a perspective view showing a quartz plate. [Figure 5] It is a partial sectional view showing a partial cross section of the quartz plate. [Figure 6] It is a plan view of the transfer mechanism. [Figure 7] It is a side view of the transfer mechanism. [Figure 8] It is a flowchart showing the processing operation in the heat treatment apparatus of FIG. 1. [Figure 9] It is a side view showing the susceptor together with a semiconductor wafer, a quartz plate, and lift pins. [Figure 10] [[ID=�5]]It is a side view showing the susceptor together with a semiconductor wafer, a quartz plate, and lift pins. [Figure 11] 它是一个侧视图,展示了带有半导体晶圆、石英板和提升销的基座。 [Figure 12] It is a graph showing the temporal temperature change of a semiconductor wafer by the heat treatment apparatus of the present embodiment. [Figure 13] It is a side view showing the susceptor of Modification 1 of the First Embodiment together with a semiconductor wafer, a quartz plate, and lift pins. [ [Figure 14] It is a side view showing the susceptor of Modification 2 of the First Embodiment together with a semiconductor wafer, a quartz plate, and lift pins. [Figure 15] This is a side view showing the susceptor of a modified example 3 of the first embodiment together with a semiconductor wafer, a quartz plate, and a lift pin. [Figure 16] This is a longitudinal cross-sectional view showing the configuration of a heat treatment apparatus for implementing the heat treatment method according to the present invention. [Figure 17] This is a flowchart showing the flow of heat treatment of a semiconductor wafer using the heat treatment apparatus of the second embodiment. [Modes for carrying out the invention]

[0020] The embodiments of the present invention will be described in detail below with reference to the drawings.

[0021] <First Embodiment> Figure 1 is a longitudinal cross-sectional view showing the configuration of the heat treatment apparatus 1 according to the present invention. The heat treatment apparatus 1 in Figure 1 is a flash lamp annealing apparatus that heats a disc-shaped semiconductor wafer W, which is used as a substrate, by flashing light onto the wafer. The size of the semiconductor wafer W to be processed is not particularly limited, but for example, it may be φ300 mm or φ450 mm (in this embodiment, it is φ300 mm). Note that in Figure 1 and subsequent figures, the dimensions and number of parts are exaggerated or simplified as necessary for ease of understanding.

[0022] The heat treatment apparatus 1 comprises a chamber 6 for housing a semiconductor wafer W, a flash heating unit 5 as a flash light irradiation unit incorporating a plurality of flash lamps FL, and a halogen heating unit 4 as a halogen light irradiation unit incorporating a plurality of halogen lamps HL. The flash heating unit 5 is located on the upper side of the chamber 6, and the halogen heating unit 4 is located on the lower side. The heat treatment apparatus 1 also includes a holding unit 7 inside the chamber 6 for holding the semiconductor wafer W in a horizontal position, 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 that controls the operating mechanisms provided in the halogen heating unit 4, the flash heating unit 5, and the chamber 6 to perform heat treatment on the semiconductor wafer W.

[0023] The flash heating unit 5, located above the chamber 6, is constructed with a light source consisting of multiple (30 in this embodiment) flash lamps FL (for example, xenon flash lamps) inside a housing 51, and a reflector 52 provided to cover the top of the light source. A lamp light emission window 53 is also mounted on the bottom of the housing 51 of the flash heating unit 5. The lamp light emission window 53, which constitutes the floor of the flash heating unit 5, is a plate-shaped quartz window made of quartz. Because the flash heating unit 5 is installed above the chamber 6, the lamp light emission window 53 faces the upper chamber window 63. The flash lamps FL irradiate the heat treatment space 65 with flash light from above the chamber 6 through the lamp light emission window 53 and the upper chamber window 63.

[0024] Each of the multiple flash lamps FL is a rod-shaped lamp with a long cylindrical shape, and they are arranged in a planar manner such that their longitudinal directions are parallel to each other along the main surface (i.e., along the horizontal direction) of the semiconductor wafer W held by the holding part 7. Therefore, the plane formed by the arrangement of the flash lamps FL is also a horizontal plane.

[0025] A flash lamp FL comprises, for example, a rod-shaped glass tube (discharge tube) containing xenon gas and having an anode and cathode connected to a capacitor at both ends, and a trigger electrode attached to the outer surface of the glass tube. Since xenon gas is an electrically insulating material, electricity does not flow through the glass tube under normal conditions, even if charge is stored in the capacitor. However, when a high voltage is applied to the trigger electrode to break the insulation, the electricity stored in the capacitor flows instantaneously through the glass tube, and light is emitted due to the excitation of xenon atoms or molecules at that time. In such a flash lamp FL, the electrostatic energy previously stored in the capacitor is converted into extremely short light pulses of 0.1 milliseconds to 100 milliseconds, giving it the characteristic of being able to emit extremely strong light compared to a continuously lit light source such as a halogen lamp HL. In other words, a flash lamp FL is a pulse-emitting lamp that emits light instantaneously in an extremely short time of less than 1 second. The emission time of the flash lamp FL can be adjusted by the coil constant of the lamp power supply that provides power to the flash lamp FL.

[0026] Furthermore, the reflector 52 is positioned above the multiple flash lamps FL so as to cover them all. The basic function of the reflector 52 is to reflect the flash light emitted from the multiple flash lamps FL towards the heat treatment space 65. The reflector 52 is made of an aluminum alloy plate, and its surface (the side facing the flash lamps FL) is roughened by blasting.

[0027] The halogen heating unit 4, located below the chamber 6, has multiple halogen lamps HL (40 in this embodiment) built into the inside of the housing 41. The halogen heating unit 4 heats the semiconductor wafer W by irradiating light from below the chamber 6 through the lower chamber window 64 into the heat treatment space 65 using the multiple halogen lamps HL.

[0028] The halogen heating section 4 consists of 40 halogen lamps HL arranged, for example, in two upper and lower sections (see Figure 1). Twenty halogen lamps HL are arranged in the upper section, which is closer to the holding section 7, and another 20 halogen lamps HL are arranged in the lower section, which is further from the holding section 7. Each halogen lamp HL is a rod-shaped lamp with a long cylindrical shape. In both the upper and lower sections, the 20 halogen lamps HL are arranged so that their longitudinal directions are parallel to each other along the main surface of the semiconductor wafer W held by the holding section 7 (i.e., along the horizontal direction). Therefore, the plane formed by the arrangement of halogen lamps HL in both the upper and lower sections is a horizontal plane.

[0029] Furthermore, in both the upper and lower sections, the halogen lamp HL is arranged in a higher density in the region facing the periphery of the semiconductor wafer W held by the holding section 7 than in the region facing the center. In other words, in both the upper and lower sections, the arrangement pitch of halogen lamp HL is shorter at the periphery than at the center of the lamp arrangement. As a result, a greater amount of light can be irradiated to the periphery of the semiconductor wafer W, where temperature drops are more likely to occur during heating by light irradiation from the halogen heating section 4.

[0030] Furthermore, the lamp group consisting of halogen lamps HL in the upper row and the lamp group consisting of halogen lamps HL in the lower row are arranged to intersect in a grid pattern. In other words, a total of 40 halogen lamps HL are arranged such that the longitudinal directions of the 20 halogen lamps HL in the upper row and the longitudinal directions of the 20 halogen lamps HL in the lower row are perpendicular to each other.

[0031] The halogen lamp HL is a filament-type light source that emits light by passing an electric current through a filament placed inside a glass tube, causing the filament to become incandescent. Inside the glass tube is a gas containing trace amounts of halogen elements (iodine, bromine, etc.) introduced into an inert gas such as nitrogen or argon. By introducing halogen elements, it is possible to set the filament temperature to a high level while suppressing filament breakage. Therefore, the halogen lamp HL has the characteristics of having a longer lifespan and being able to continuously emit strong light compared to a normal incandescent light bulb. In other words, the halogen lamp HL is a continuous-lighting lamp that emits light continuously for at least 1 second or more. Furthermore, because the halogen lamp HL is a rod-shaped lamp, it has a long lifespan, and by arranging the halogen lamp HL horizontally, the radiation efficiency to the semiconductor wafer W above is excellent.

[0032] Furthermore, a reflector 43 is also provided inside the housing 41 of the halogen heating unit 4, below the two-tiered halogen lamps HL (see Figure 1). The reflector 43 reflects the light emitted from the multiple halogen lamps HL towards the heat treatment space 65.

[0033] As shown in Figure 1, the chamber 6 is equipped with two radiation thermometers (pyrometers in this embodiment): an upper radiation thermometer 25 and a lower radiation thermometer 20. The upper radiation thermometer 25 is positioned diagonally above the semiconductor wafer W held by the susceptor 74 and measures the temperature of the upper surface by receiving infrared light emitted from the upper surface of the semiconductor wafer W. The infrared sensor 29 of the upper radiation thermometer 25 is equipped with an InSb (indium antimony) optical element to respond to rapid temperature changes on the upper surface of the semiconductor wafer W at the moment of flash light irradiation. On the other hand, the lower radiation thermometer 20 is positioned diagonally below the semiconductor wafer W held by the susceptor 74 and measures the temperature of the lower surface by receiving infrared light emitted from the lower surface of the semiconductor wafer W.

[0034] The control unit 3 controls the various operating mechanisms provided in the heat treatment apparatus 1. The hardware configuration of the control unit 3 is similar to that of a general computer. Specifically, the control unit 3 includes a CPU, which is a circuit that performs various calculations; a ROM, which is a read-only memory that stores basic programs; a RAM, which is a read-write memory that stores various information; and a magnetic disk that stores control software and data. Processing in the heat treatment apparatus 1 proceeds when the CPU of the control unit 3 executes a predetermined processing program. The transfer mechanism 10 is also controlled by the control unit 3. Specifically, the control unit 3 controls the operation of the lifting mechanism 14 and the horizontal movement mechanism 13 that constitute the transfer mechanism 10.

[0035] In addition to the above configuration, the heat treatment apparatus 1 is equipped with various cooling structures to prevent excessive temperature rise in the halogen heating section 4, flash heating section 5, and chamber 6 due to thermal energy generated from the halogen lamp HL and flash lamp FL during the heat treatment of semiconductor wafers W. For example, water cooling pipes (not shown) are provided in the wall of the chamber 6. Furthermore, the halogen heating section 4 and flash heating section 5 are air-cooled structures that dissipate heat by forming a gas flow inside. 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 section 5 and the upper chamber window 63.

[0036] Chamber 6 is constructed by attaching quartz chamber windows to 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. The upper opening is closed by an upper chamber window 63, and the lower opening is closed by a lower chamber window 64. The upper chamber window 63, which constitutes the ceiling of chamber 6, is a disc-shaped member made of quartz and functions as a quartz window that transmits flash light emitted from the flash heating unit 5 into chamber 6. Similarly, the lower chamber window 64, which constitutes the floor of chamber 6, is also a disc-shaped member made of quartz and functions as a quartz window that transmits light from the halogen heating unit 4 into chamber 6. The heat treatment apparatus 1 heats the semiconductor wafer W by irradiating the semiconductor wafer W with light in this manner.

[0037] Furthermore, a reflective ring 68 is attached to the upper part of the inner wall surface of the chamber side portion 61, and a reflective ring 69 is attached to the lower part. Both reflective rings 68 and 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 portion 61. On the other hand, the lower reflective ring 69 is attached by fitting it from the lower side of the chamber side portion 61 and securing it with screws (not shown). In other words, both reflective rings 68 and 69 are detachably attached to the chamber side portion 61. The inner space of the chamber 6, that is, the space enclosed by the upper chamber window 63, the lower chamber window 64, the chamber side portion 61, and the reflective rings 68 and 69, is defined as the heat treatment space 65.

[0038] By attaching the reflective rings 68 and 69 to the chamber side portion 61, a recess 62 is formed on the inner wall surface of the chamber 6. Specifically, the recess 62 is formed by the central portion of the inner wall surface of the chamber side portion 61 where the reflective rings 68 and 69 are not attached, the lower end surface of the reflective ring 68, and the upper end surface of the reflective 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 holding portion 7 that holds the semiconductor wafer W. The chamber side portion 61 and the reflective rings 68 and 69 are made of a metal material (for example, stainless steel) with excellent strength and heat resistance.

[0039] Furthermore, a transport opening (furnace opening) 66 is provided on the side portion 61 of the chamber for loading and unloading semiconductor wafers W into and out of the chamber 6. The transport opening 66 can be opened and closed by a gate valve 185. The transport opening 66 is connected in communication with the outer surface of the recess 62. Therefore, when the gate valve 185 is open, semiconductor wafers W can be loaded into the heat treatment space 65 from the transport opening 66 through the recess 62 and unloaded from the heat treatment space 65. When the gate valve 185 closes the transport opening 66, the heat treatment space 65 inside the chamber 6 becomes a sealed space.

[0040] Furthermore, through-holes 61a and 61b are drilled in the side portion 61 of the chamber. Through-hole 61a is a cylindrical hole for guiding infrared light emitted from the upper surface of the semiconductor wafer W held by the susceptor 74 (described later) to the infrared sensor 29 of the upper radiation thermometer 25. On the other hand, through-hole 61b is a cylindrical hole for guiding infrared light emitted from the lower surface of the semiconductor wafer W to the infrared sensor 24 of the lower radiation thermometer 20. Through-holes 61a and 61b are provided at an inclination with respect to the horizontal direction such that their axes in the direction of penetration intersect with the main surface of the semiconductor wafer W held by the susceptor 74. A transparent window 26 made of calcium fluoride material that transmits infrared light in the wavelength range measurable by the upper radiation thermometer 25 is attached to the end of through-hole 61a facing the heat treatment space 65. Furthermore, a transparent window 21 made of barium fluoride material that transmits infrared light in the wavelength range measurable by the lower radiation thermometer 20 is attached to the end of the through hole 61b facing the heat treatment space 65.

[0041] Furthermore, a gas supply hole 81 for supplying a processing gas to the heat treatment space 65 is formed in the upper part of the inner wall of the chamber 6. The gas supply hole 81 is formed in a position above the recess 62 and may be provided in the reflecting ring 68. The gas supply hole 81 is connected to a 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 connected to a processing gas supply source 85. A valve 84 is also interposed in the path of the gas supply pipe 83. When the valve 84 is opened, processing gas is supplied from the processing gas supply source 85 to the buffer space 82. The processing gas that flows into the buffer space 82 spreads out within the buffer space 82, which has less fluid resistance than the gas supply hole 81, and is supplied from the gas supply hole 81 into the heat treatment space 65. As the processing gas, for example, an inert gas such as nitrogen (N2), or a reactive gas such as hydrogen (H2), ammonia (NH3), or a mixed gas of these can be used (in this embodiment, nitrogen gas).

[0042] On the other hand, a gas exhaust port 86 for exhausting gas from the heat treatment space 65 is formed in the lower part of the inner wall of the chamber 6. The gas exhaust port 86 is formed in a position below the recess 62 and may be provided in the reflecting ring 69. The gas exhaust port 86 is connected to a gas exhaust pipe 88 via a buffer space 87 formed in an annular shape inside the side wall of the chamber 6. The gas exhaust pipe 88 is connected to the exhaust section 190. A valve 89 is interposed in the path of the gas exhaust pipe 88. When the valve 89 is opened, the gas from the heat treatment space 65 is discharged from the gas exhaust port 86 through the buffer space 87 to the gas exhaust pipe 88. Note that there may be multiple gas supply holes 81 and gas exhaust holes 86 along the circumferential direction of the chamber 6, or they may be slit-shaped. Also, the processing gas supply source 85 and the exhaust section 190 may be mechanisms provided in the heat treatment apparatus 1, or they may be utilities of the factory where the heat treatment apparatus 1 is installed.

[0043] Furthermore, a gas exhaust pipe 191 for discharging gas from the heat treatment space 65 is connected to the tip of the transport opening 66. The gas exhaust pipe 191 is connected to the exhaust section 190 via a valve 192. By opening the valve 192, the gas in the chamber 6 is exhausted through the transport opening 66.

[0044] 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 susceptor 74. The base ring 71, the connecting part 72, and the susceptor 74 are all made of quartz. In other words, the entire holding part 7 is made of quartz.

[0045] The base ring 71 is a quartz material with an arc shape, partially missing from its annular shape. This missing portion is provided to prevent interference between the transfer arm 11 of the transfer mechanism 10 (described later) 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). Multiple connecting parts 72 (four in this embodiment) are erected on the upper surface of the base ring 71 along the circumferential direction of its annular shape. The connecting parts 72 are also made of quartz material and are fixed to the base ring 71 by welding.

[0046] The susceptor 74 is supported by four connecting parts 72 provided on the base ring 71. Figure 3 is a plan view of the susceptor 74.

[0047] The susceptor 74 comprises a retaining plate 75 and a plurality of support pins 77. The retaining plate 75 is a substantially circular, flat member made of quartz. The diameter of the retaining plate 75 is, for example, larger than the diameter of the semiconductor wafer W. That is, the retaining plate 75 has a planar size larger than, for example, the semiconductor wafer W.

[0048] The upper surface of the retaining plate 75 is a flat retaining surface 75a. Multiple support pins 77 are erected on the retaining surface 75a of the retaining plate 75. In this embodiment, a total of 12 support pins 77 are erected at 30° intervals along the circumference of the outer circle and concentric circle of the retaining surface 75a. The diameter of the circle in which the 12 support pins 77 are arranged (the distance between opposing support pins 77) is smaller than the diameter of the semiconductor wafer W. For example, if the diameter of the semiconductor wafer W is φ300 mm, then preferably it is φ270 mm to φ280 mm (φ270 mm in this embodiment). Each support pin 77 is made of quartz. Multiple support pins 77 may be provided on the upper surface of the retaining plate 75 by welding, or they may be machined integrally with the retaining plate 75.

[0049] Returning to Figure 2, the four connecting parts 72 erected on the base ring 71 and the peripheral edge of the holding plate 75 of the susceptor 74 are fixed by welding. In other words, the susceptor 74 and the base ring 71 are fixedly connected by the connecting parts 72. The holding part 7 is mounted in the chamber 6 by the base ring 71 of the holding part 7 being supported by the wall surface of the chamber 6. When the holding part 7 is mounted in the chamber 6, the holding plate 75 of the susceptor 74 is in a horizontal position (a position in which the normal coincides with the vertical direction). In other words, the holding surface 75a of the holding plate 75 is a horizontal plane.

[0050] The semiconductor wafer W, once placed in the chamber 6, is held horizontally on the susceptor 74 of the holding unit 7 mounted in the chamber 6. At this time, the semiconductor wafer W is supported by 12 support pins 77 erected on the holding plate 75 and held by the susceptor 74. More precisely, the upper ends of the 12 support pins 77 contact the lower surface of the semiconductor wafer W to support it. Since the height of the 12 support pins 77 (the distance from the upper end of the support pins 77 to the holding surface 75a of the holding plate 75) is uniform, the semiconductor wafer W can be supported horizontally by the 12 support pins 77. The semiconductor wafer W is also supported by multiple support pins 77 at a predetermined distance from the holding surface 75a of the holding plate 75.

[0051] Furthermore, as shown in Figures 2 and 3, the holding plate 75 of the susceptor 74 has an opening 78 that penetrates vertically. The opening 78 is provided for the lower radiation thermometer 20 to receive synchrotron radiation (infrared light) emitted from the lower surface of the semiconductor wafer W. That is, the lower radiation thermometer 20 measures the temperature of the semiconductor wafer W by receiving light emitted from the lower surface of the semiconductor wafer W through the opening 78 and a transparent window 21 fitted in a through hole 61b of the chamber side 61. In addition, the holding plate 75 of the susceptor 74 has four through holes 79 through which the lift pins 12 of the transfer mechanism 10, which will be described later, pass for the transfer of the semiconductor wafer W. Furthermore, the holding plate 75 has four through holes 76 through which the lift pins 12 of the transfer mechanism 10, which will be described later, pass for the vertical movement of the quartz plate 100.

[0052] Figure 4 is a perspective view showing the quartz plate 100. The quartz plate 100 (see Figure 4) is placed on the holding surface 75a of the holding plate 75. The quartz plate 100 is formed in the shape of a quartz disc, for example, having an outer circumference concentric with the outer circumference of the holding surface 75a of the holding plate 75. The quartz plate 100 has an opening 108 that penetrates vertically, similar to the holding plate 75. The opening 108 is provided so that the lower radiation thermometer 20 can receive the synchrotron radiation (infrared light) emitted from the lower surface of the quartz plate 100. The quartz plate 100 is placed on the holding plate 75 such that its opening 108 is positioned directly above the opening 78. Therefore, the lower radiation thermometer 20 can receive the synchrotron radiation emitted from the lower surface of the semiconductor wafer W. Furthermore, the quartz plate 100 has four through-holes 109 through which the lift pins 12 of the transfer mechanism 10 (described later) pass for the transfer of the semiconductor wafer W. In addition, the quartz plate 100 has pin through-holes 107 through which support pins 77 erected on the disc-shaped holding surface 75a pass.

[0053] Furthermore, the planar size of the quartz plate 100 is, for example, ±20% of the planar size of the semiconductor wafer W. For example, if the diameter of the semiconductor wafer W is φ300 mm, it is preferable that the diameter of the quartz plate 100 be approximately φ240 mm to φ360 mm. As will be explained later, the quartz plate 100 cools the semiconductor wafer W by contacting one side of the semiconductor wafer W (the front surface Wf or the back surface Wb). In this embodiment, the quartz plate 100 contacts the back surface of the semiconductor wafer W. Also, the closer the planar size of the quartz plate 100 is to the planar size of the semiconductor wafer W, the more the entire surface of the semiconductor wafer W is cooled by the quartz plate 100. Therefore, the cooling efficiency of the semiconductor wafer W by the quartz plate 100 is improved. However, in the semiconductor wafer W, the cooling rate tends to be faster at the edges than at the center. Therefore, even if the quartz plate 100 is of a flat size that can only contact the central part of the semiconductor wafer W, the semiconductor wafer W is cooled efficiently.

[0054] Figure 5 is a partial cross-sectional view showing a partial cross-section of the quartz plate 100. As shown in Figure 5, recesses 101 are formed on the surface 100a of the quartz plate 100 that contacts the semiconductor wafer W (hereinafter referred to as the contact surface 100a). For example, multiple recesses 101 are formed. Preferably, the recesses 101 are linear grooves. These linear grooves are formed, for example, parallel to each other. If the surface of the quartz plate 100 is smooth and no recesses 101 are formed, the quartz plate 100 and the semiconductor wafer W may be difficult to separate after contact. Therefore, by forming recesses 101 on the quartz plate 100, a gap exists between the quartz plate 100 and the semiconductor wafer W even when they are in contact. This prevents adhesion between the quartz plate 100 and the semiconductor wafer W. This gap can promote separation between the contacting semiconductor wafer W and the quartz plate 100. Therefore, the separation of the quartz plate 100 and the semiconductor wafer W after the cooling of the semiconductor wafer W by the quartz plate 100 occurs smoothly.

[0055] Figure 6 is a plan view of the transfer mechanism 10. The transfer mechanism 10 comprises two transfer arms 11. The transfer arms 11 are shaped like arcs that generally follow the annular recess 62. Two lift pins 12 are erected on each transfer arm 11. The transfer arms 11 and lift pins 12 are made of quartz. Each transfer arm 11 is rotatable by a horizontal movement mechanism 13. The horizontal movement mechanism 13 moves the transfer arms 11 horizontally between a transfer operation position A (solid line position in Figure 6) for transferring the semiconductor wafer W to the holding part 7, a cooling operation position B (dotted-dotted line position in Figure 6) for raising and lowering the quartz plate 100 (and semiconductor wafer W), and a retracted position C (double-dotted-dotted line position in Figure 6) where the arms do not overlap with the semiconductor wafer W held by the holding part 7 in a plan view. The horizontal movement mechanism 13 may consist of individual motors that rotate each transfer arm 11, or it may consist of a linkage mechanism that uses a single motor to rotate a pair of transfer arms 11 in conjunction. The retracted position C is directly above the base ring 71 of the holding part 7. Since the base ring 71 is placed on the bottom surface of the recess 62, the retracted position C of the transfer arm 11 is inside the recess 62.

[0056] Figure 7 is a side view of the transfer mechanism 10. The transfer mechanism 10 includes a lifting mechanism 14. The lifting mechanism 14 moves the transfer arm 11 and the lift pin 12 in the vertical direction. As shown in Figure 7, the lifting mechanism 14 raises and lowers the transfer arm 11 to the highest position for receiving the semiconductor wafer W (the height position of the transfer arm 11 corresponding to the transport position X described later), the lowest position for performing heat treatment on the semiconductor wafer W (the height position of the transfer arm 11 corresponding to the heating position Y described later), and the position in between where the quartz plate 100 contacts the back surface Wb of the semiconductor wafer W (the height position of the transfer arm 11 corresponding to the cooling position Z described later).

[0057] Furthermore, an exhaust mechanism (not shown) is also provided near the area where the drive unit (horizontal movement mechanism 13 and lifting mechanism 14) of the transfer mechanism 10 is located, so that the atmosphere around the drive unit of the transfer mechanism 10 is discharged to the outside of the chamber 6.

[0058] Figure 8 is a flowchart showing the processing operation in the heat treatment apparatus 1. Figures 9 to 11 are side views showing the susceptor 74 together with the semiconductor wafer W, quartz plate 100, and lift pins 12. Figure 9 shows the semiconductor wafer W positioned at the transport position X, Figure 10 at the heating position Y, and Figure 11 at the cooling position Z.

[0059] The specific operation of the heat treatment apparatus 1 will be explained below with reference to Figures 8 to 11. First, prior to processing the semiconductor wafer W, the supply valve 84 is opened and the exhaust valve 89 is opened, initiating the supply and exhaust of air into the chamber 6. When valve 84 is opened, nitrogen gas is supplied to the heat treatment space 65 from the gas supply hole 81. When 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 top of the heat treatment space 65 in the chamber 6 flows downward and is exhausted from the bottom of the heat treatment space 65.

[0060] Furthermore, when valve 192 is opened, the gas inside chamber 6 is also exhausted from the transport opening 66. In addition, the atmosphere around the drive unit of the transfer mechanism 10 is also exhausted by an exhaust mechanism (not shown). During the heat treatment of semiconductor wafers W in the heat treatment apparatus 1, nitrogen gas is continuously supplied to the heat treatment space 65, and the amount supplied is changed as appropriate according to the processing step.

[0061] Next, the gate valve 185 opens, the transport opening 66 is opened, and the semiconductor wafer W to be processed is transported through the transport opening 66 by a transport robot outside the apparatus into the heat treatment space 65 inside the chamber 6. At this time, there is a risk that the atmosphere outside the apparatus may be drawn in as the semiconductor wafer W is transported in, but since nitrogen gas is continuously supplied to the chamber 6, the nitrogen gas flows out from the transport opening 66, minimizing the entrainment of such external atmosphere.

[0062] The semiconductor wafer W, loaded by the transport robot, moves forward to a position directly above the holding section 7 and stops (step S1). Then, as the pair of transfer arms 11 of the transfer mechanism 10 move horizontally from the retracted position C (see Figure 6) to the transfer operation position A (see Figure 6) and rise, the lift pin 12 passes through the through hole 79 of the susceptor 74 and the through hole 109 of the quartz plate 100, protruding from the upper surface of the quartz plate 100 to receive the semiconductor wafer W. At this time, the lift pin 12 rises above the upper end of the support pin 77.

[0063] After the semiconductor wafer W is placed on the lift pin 12, the transport robot exits the heat treatment space 65, and the transport opening 66 is closed by the gate valve 185. Then, as a pair of transfer arms 11 descend, the semiconductor wafer W is transferred from the transfer mechanism 10 to the susceptor 74 of the holding unit 7 and held from below in a horizontal position. The semiconductor wafer W is supported by a plurality of support pins 77 erected on the holding plate 75 and held by the susceptor 74. The semiconductor wafer W is also held in the holding unit 7 with the surface to be processed facing upwards. That is, as shown in Figure 10, the semiconductor wafer W moves to the heating position Y (step S2). Here, the position in which the semiconductor wafer W is held in the holding unit 7 is defined as the heating position Y (see Figures 8 and 10). A predetermined gap is formed between the back surface Wb of the semiconductor wafer W (the main surface opposite to the front surface Wf) supported by the plurality of support pins 77 and the holding surface 75a of the holding plate 75. The pair of transfer arms 11, which have descended to below the susceptor 74, are moved to the retracted position C, i.e., inside the recess 62, by the horizontal movement mechanism 13.

[0064] After the semiconductor wafer W is held horizontally from below by the susceptor 74 of the holding part 7 made of silica, the 40 halogen lamps HL of the halogen heating part 4 are lit simultaneously to start preheating (assisted heating) (preheating process) (step S3). The halogen light emitted from the halogen lamps HL passes through the lower chamber window 64, susceptor 74, and quartz plate 100, which are made of silica, and irradiates the lower surface of the semiconductor wafer W. The semiconductor wafer W is preheated and its temperature rises due to the light irradiation from the halogen lamps HL. The transfer arm 11 of the transfer mechanism 10 is retracted inside the recess 62, so it does not interfere with heating by the halogen lamps HL.

[0065] The temperature of the semiconductor wafer W, which is heated by light irradiation from the halogen lamp HL, is measured by the lower radiation thermometer 20. The measured temperature of the semiconductor wafer W is transmitted to the control unit 3. The control unit 3 monitors whether the temperature of the semiconductor wafer W, which is heated by light irradiation from the halogen lamp HL, has reached a predetermined preheating temperature T1, and controls the output of the halogen lamp HL. That is, the control unit 3 feedback-controls the output of the halogen lamp HL based on the measurement value from the lower radiation thermometer 20 so that the temperature of the semiconductor wafer W reaches the preheating temperature T1.

[0066] After the semiconductor wafer W reaches the preheating temperature T1, the control unit 3 temporarily maintains the semiconductor wafer W at that preheating temperature T1. Specifically, when the temperature of the semiconductor wafer W, as measured by the lower 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 at approximately the preheating temperature T1.

[0067] By performing preheating with halogen lamps HL in this manner, the entire semiconductor wafer W is uniformly heated to the preheating temperature T1. During the preheating stage with halogen lamps HL, the temperature of the peripheral parts of the semiconductor wafer W, where heat dissipation is more likely, tends to be lower than that of the central part. However, the density of halogen lamps HL in the halogen heating section 4 is higher in the region facing the peripheral parts of the semiconductor wafer W than in the region facing the central part. As a result, more light is irradiated to the peripheral parts of the semiconductor wafer W, where heat dissipation is more likely, making it possible to achieve a uniform in-plane temperature distribution of the semiconductor wafer W during the preheating stage.

[0068] When the semiconductor wafer W reaches the preheating temperature T1 and a predetermined time has elapsed, the flash lamp FL of the flash heating unit 5 irradiates the surface of the semiconductor wafer W held by the susceptor 74 with flash light. At this time, a portion of the flash light emitted from the flash lamp FL goes directly into the chamber 6, and another portion is reflected by the reflector 52 before going into the chamber 6, and the semiconductor wafer W is flash-heated by the irradiation of these flash lights (main heating process) (step S4).

[0069] Flash heating is performed by irradiation with flash light (blink) from a flash lamp FL, which allows the surface temperature of the semiconductor wafer W to be raised in a short time. In other words, the flash light emitted from the flash lamp FL is an extremely short and strong flash with an irradiation time (flash light irradiation time) of about 0.1 milliseconds 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, which is flash-heated by irradiation with flash light from the flash lamp FL, rises instantaneously to a processing temperature T2 of 1000°C or more, and then rapidly decreases.

[0070] After the flash heating process is completed and a predetermined time has elapsed, the halogen lamp HL is turned off. This causes the semiconductor wafer W to rapidly cool down from the preheating temperature T1. The temperature of the semiconductor wafer W during the cooling process is measured by the lower 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 cooled down to the predetermined temperature based on the measurement result from the lower radiation thermometer 20.

[0071] Furthermore, the control unit 3 brings the quartz plate 100 into contact with the semiconductor wafer W after a predetermined time t1 has elapsed since the semiconductor wafer W reached its maximum temperature (processing temperature T2) due to flash light irradiation from the flash lamp FL (step S5). Here, the predetermined time t1 is, for example, 0.1 seconds to 3 seconds. By setting such a predetermined time, the semiconductor wafer W can be cooled down rapidly.

[0072] The movement of the quartz plate 100 is performed by the lifting mechanism 14. Specifically, when the lifting mechanism 14 raises the pair of transfer arms 11 in the cooling operation position B (see Figures 6 and 11), a total of four lift pins 12 pass through the through holes 76 (see Figure 2) drilled in the susceptor 74. The upper ends of the lift pins 12 then protrude from the upper surface of the susceptor 74. As shown in Figure 11, the upper ends of the lift pins 12 protruding from the upper surface of the susceptor 74 place the quartz plate 100 on them and move the quartz plate 100 upward. The quartz plate 100, moved upward by the lift pins 12, comes into contact with the back surface Wb of the semiconductor wafer W, which is supported by the support pins 77. As the upper end of the lift pin 12 rises, the quartz plate 100 comes into contact with the semiconductor wafer W. Further upward movement of the upper end of the lift pin 12 continues even after the semiconductor wafer W is placed on it. The lifting mechanism 14 positions the semiconductor wafer W and the quartz plate 100 at the position furthest from the susceptor 74 and stops them. At this time, the back surface Wb of the semiconductor wafer W comes into contact with the quartz plate 100, and the semiconductor wafer W is cooled by the quartz plate 100. That is, the semiconductor wafer W moves to the cooling position Z shown in Figure 11 (cooling process) (step S6). The height position of the quartz plate 100 from the time it comes into contact with the back surface Wb of the semiconductor wafer W until the semiconductor wafer W rises to the cooling position Z is the contact position between the quartz plate 100 and the semiconductor wafer W.

[0073] After the semiconductor wafer W has cooled to below a predetermined temperature, the lifting mechanism 14 lowers the semiconductor wafer W and the quartz plate 100. Then, as shown in Figure 10, the semiconductor wafer W moves back to the heating position Y (step S7). Specifically, the lifting mechanism 14 lowers a pair of transfer arms 11 in the cooling operation position B and removes the lift pins 12 from the through holes 76. At this time, the semiconductor wafer W is placed on the upper end of the support pins 77. The quartz plate 100 is then placed on the susceptor 74. In this way, the semiconductor wafer W and the quartz plate 100 are separated from each other. The height position of the quartz plate 100 from the time it leaves the back surface Wb of the semiconductor wafer W until it is placed on the susceptor 74 is the separated position between the quartz plate 100 and the semiconductor wafer W.

[0074] Then, as the transfer arm 11 moves horizontally to the transfer position A and rises, the lift pin 12 protrudes from the through hole 79 drilled in the susceptor 74 and the through hole 109 drilled in the quartz plate 100, moving the heat-treated semiconductor wafer W upward. As a result, the semiconductor wafer W moves to the transport position X (step S8).

[0075] Subsequently, the transport opening 66, which had been closed by the gate valve 185, is opened, and the semiconductor wafer W placed on the lift pin 12 is removed from the chamber 6 by a transport robot outside the apparatus, completing the heat treatment of the semiconductor wafer W.

[0076] As described above, the lifting mechanism 14 moves the quartz plate 100 up and down relative to the semiconductor wafer W between a contact position where the quartz plate 100 is in contact with the back surface Wb of the semiconductor wafer W and a separated position where the quartz plate 100 is separated from the semiconductor wafer W. In other words, the semiconductor wafer W and the quartz plate 100 move relative to each other between the separated position and the contact position.

[0077] Figure 12 is a graph showing the temperature change of a semiconductor wafer W over time using the heat treatment apparatus 1 of this embodiment. The dotted line in Figure 12 shows the temperature change of a semiconductor wafer W over time using natural cooling without the use of a quartz plate 100, for comparison.

[0078] In Figure 12, point O indicates the time when the semiconductor wafer W reaches its maximum temperature, and point P indicates the time when the semiconductor wafer W and the quartz plate 100 come into contact. As shown in Figure 12, when the semiconductor wafer W comes into contact with the quartz plate 100 after reaching its maximum temperature, the rate of cooling after contact with the quartz plate 100 is faster compared to when there is no contact with the quartz plate 100. In this embodiment, since the semiconductor wafer W and the quartz plate 100 come into contact immediately after the semiconductor wafer W reaches its maximum temperature, the rate of cooling of the semiconductor wafer W after heat treatment can be accelerated. This is expected to prevent the deactivation of impurities in the active state in the semiconductor wafer W. This effect is particularly pronounced when the semiconductor wafer W and the quartz plate 100 come into contact within 0.1 to 3 seconds from the time the semiconductor wafer W reaches its maximum temperature.

[0079] <Modification 1 of the first embodiment> The following describes a heat treatment apparatus according to Modification 1 of the First Embodiment. Figure 13 is a side view showing the susceptor 274 of Modification 1 of the First Embodiment together with a semiconductor wafer W, a quartz plate 100, and a lift pin 12. The heat treatment apparatus according to Modification 1 is equipped with a susceptor 274 instead of a susceptor 74. The susceptor 274 is equipped with a holding plate 275 and a plurality of support pins 77. The holding plate 275 has a hollow portion 279 formed inward from the position where the support pins 77 are erected. The formation of this hollow portion 279 eliminates the need to form a plurality of through holes 79, as in the holding plate 75 of the First Embodiment. In other words, by forming a single hollow portion 279, the lift pin 12 can pass through the hollow portion 279 and move the semiconductor wafer W or the quartz plate 100 upward, whether at the transfer operation position A or the cooling operation position B. According to the heat treatment apparatus according to Modification 1 of the First Embodiment, the configuration of the holding plate 75 can be simplified.

[0080] <Modification 2 of the first embodiment> The following describes a heat treatment apparatus according to Modification 2 of the First Embodiment. Figure 14 is a side view showing the susceptor 374 of Modification 2 of the First Embodiment together with a semiconductor wafer W, a quartz plate 300, and lift pins 12. The heat treatment apparatus according to Modification 2 is equipped with a susceptor 374 instead of a susceptor 74. The susceptor 374 is equipped with a holding plate 375 and a plurality of support pins 77. The holding plate 375 does not have through holes 76. In addition, a quartz plate holding portion 376 is erected on the susceptor 374. The quartz plate 300 is held above the semiconductor wafer W (on the flash heating portion 5 side) by the quartz plate holding portion 376. The quartz plate 300 does not need to have through holes for the lift pins or through holes for the support pins 77.

[0081] When the semiconductor wafer W and the quartz plate 300 come into contact using the heat treatment apparatus according to this modified example 2, first, the lift pin 12 passes through the through hole 79 by the lifting mechanism 14. Then, as the lift pin 12 moves further upward, the semiconductor wafer W is placed on the lift pin 12 and moves upward. As the surface of the semiconductor wafer W comes into contact with the quartz plate 300, the semiconductor wafer W is cooled by the quartz plate 300. For this reason, the configuration of the quartz plate 300 and the holding plate 375 can be simplified.

[0082] <Modification 3 of the first embodiment> The following describes a heat treatment apparatus according to Modification 3 of the first embodiment. Figure 15 is a side view showing the susceptor 474 of Modification 3 of the first embodiment together with a semiconductor wafer W, a quartz plate 400, and a lift pin 12. The heat treatment apparatus according to Modification 3 is equipped with a susceptor 474 in place of the susceptor 374 of Modification 2. This heat treatment apparatus according to Modification 3 is equipped with a quartz plate holder 460 in place of the quartz plate holder 376 of Modification 2 described above. Therefore, the quartz plate holder 376 is not erected on the susceptor 474. The quartz plate holder 460 is fixed to the chamber side portion 61. The quartz plate 400 is held above the semiconductor wafer W by the quartz plate holder 460. Even with this heat treatment apparatus according to Modification 3, the configuration of the quartz plate 400 and the holding plate 375 can be simplified.

[0083] <Second Embodiment> The following describes a heat treatment apparatus 2 according to the second embodiment. Figure 16 is a longitudinal cross-sectional view showing the configuration of the heat treatment apparatus 2 according to the present invention. The heat treatment apparatus 2 in Figure 16 is a flash lamp annealing apparatus that heats a disc-shaped semiconductor wafer W, which is used as a substrate, by irradiating it with flash light.

[0084] The heat treatment apparatus 2 includes a flash heating unit 250 in place of the flash heating unit 5 in the heat treatment apparatus 1. Furthermore, the heat treatment apparatus 2 does not include the halogen heating unit 4 found in the heat treatment apparatus 1. In the description of the second embodiment, components similar to those described in the first embodiment are denoted by the same reference numerals, and their descriptions are omitted.

[0085] The flash heating unit 250, located above the chamber 6, is configured inside the housing 51 and comprises a light source consisting of multiple flash lamps FL and a reflector 52 provided to cover the top of the light source. For example, 60 flash lamps FL are arranged in two upper and lower rows (see Figure 16). 30 flash lamps FL(D) are arranged in the lower row, closer to the holding unit 7, while 30 flash lamps FL(U) are arranged in the upper row, further from the holding unit 7. In both the upper and lower rows, the 30 flash lamps FL are arranged so that their longitudinal directions are parallel to each other along the main surface of the semiconductor wafer W held by the holding unit 7 (i.e., along the horizontal direction). Therefore, the planes formed by the arrangement of flash lamps FL(U) and FL(D) in both the upper and lower rows are horizontal planes. Flash lamps FL(U) function as the first flash light irradiation unit, and flash lamps FL(D) function as the second flash light irradiation unit.

[0086] In addition, the flash lamps FL(U) and FL(D) in the second embodiment also emit flash light with an extremely short irradiation time of 0.1 milliseconds to 100 milliseconds, similar to the flash lamp FL in the first embodiment.

[0087] In the preheating step of the second embodiment, the flash lamp FL(U) irradiates the semiconductor wafer W held in the holding part 7 with flash light to raise the surface of the semiconductor wafer W from room temperature to the preheating temperature T1. Subsequently, in the main heating step, the flash lamp FL(D) irradiates the semiconductor wafer W, which has been raised to the preheating temperature T1, with flash light to raise the surface of the semiconductor wafer W to a processing temperature T2 that is higher than the preheating temperature T1. Note that the flash lamp FL (first flash lamp) that raises the temperature to the preheating temperature T1 may be the flash lamp FL(D). The flash lamp FL (second flash lamp) that raises the temperature to the processing temperature T2 is a different flash lamp FL from the first flash lamp.

[0088] Figure 17 is a flowchart showing the flow of heat treatment of a semiconductor wafer W by the heat treatment apparatus 2 of the second embodiment.

[0089] The specific operation of the heat treatment apparatus 2 will now be described with reference to Figures 16 and 17. First, the semiconductor wafer W is brought into the heat treatment space 65 in the chamber 6 in the same manner as in the first embodiment.

[0090] The semiconductor wafer W, brought in by the transport robot, moves forward to a position directly above the holding section 7 and stops (step S11). Then, the pair of transfer arms 11 of the transfer mechanism 10 move, and the semiconductor wafer W is placed on the lift pin 12. After that, the transport robot exits the heat treatment space 65, and the gate valve 185 closes the transport opening 66. Then, as the pair of transfer arms 11 descend, the semiconductor wafer W is transferred from the transfer mechanism 10 to the susceptor 74 of the holding section 7 and held from below in a horizontal position. The semiconductor wafer W is supported by a plurality of support pins 77 erected on the holding plate 75 and held by the susceptor 74. The semiconductor wafer W is also held in the holding section 7 with the surface to be processed facing upwards. That is, the semiconductor wafer W moves to the heating position Y (step S12).

[0091] After the semiconductor wafer W is held horizontally from below by the susceptor 74 of the holding part 7 made of silica, the first flash lamps are simultaneously lit to start preheating (assisted heating) (first flash light irradiation step) (step S13). By receiving light irradiation from the first flash lamps, the semiconductor wafer W is preheated and its surface temperature rises from room temperature to the preheating temperature T1. The preheating temperature T1 at this time is, for example, 700°C.

[0092] After the surface temperature of the semiconductor wafer W reaches the preheating temperature T1, the second flash lamps are simultaneously lit to begin the main heating process (second flash light irradiation process) (step S14). By receiving light irradiation from the second flash lamps, the surface temperature of the semiconductor wafer W is raised from the preheating temperature T1 to a higher processing temperature T2. Here, it is preferable that the interval t2 between the emission of light from the first flash lamp and the emission of light from the second flash lamp is within 1 second. This is because heating by light irradiation from the flash lamps raises the temperature of only the surface portion of the semiconductor wafer W, and if the interval between the emission of light from the first flash lamp and the emission of light from the second flash lamp is long, the semiconductor wafer W will cool down rapidly.

[0093] After heating by light irradiation from the first and second flash lamps is completed, the lift pin 12 of the transfer arm 11 moves the semiconductor wafer W upward. This moves the semiconductor wafer W to the transport position X (step S15). Then, the semiconductor wafer W is removed from the heat treatment apparatus 2 by the transport robot.

[0094] As described above, the heat treatment apparatus 2 according to the second embodiment is able to raise the temperature to the preheating temperature and the temperature to the treatment temperature by flash light irradiation, thereby raising the temperature of only the surface of the semiconductor wafer W without significantly raising the temperature of the back surface. As a result, after the flash light irradiation is completed, a rapid heat conduction occurs from the surface to the back surface of the semiconductor wafer W, which accelerates the rate of cooling of the semiconductor wafer W after heat treatment. This prevents the deactivation of impurities activated by flash light irradiation.

[0095] As described above, by raising the temperature only in a relatively shallow area from the surface of the semiconductor wafer W using the heat treatment apparatus 2, it is expected that the deactivation of impurities in the semiconductor wafer W that are in an active state can be prevented. Furthermore, since the halogen heating unit 4 in the first embodiment is not required as a heat source for preheating in the heat treatment apparatus 2, the configuration of the apparatus is simplified.

[0096] <Other> In the first embodiment described above, the flash heating unit 5 is equipped with 30 flash lamps FL, but it is not limited to this, and the number of flash lamps FL can be any number. Also, the flash lamps FL are not limited to xenon flash lamps, but may be krypton flash lamps. Similarly, the number of halogen lamps HL provided in the halogen heating unit 4 is not limited to 40, but can be any number. Furthermore, in the second embodiment described above, it is not limited to 60 flash lamps divided into upper and lower stages. The number of flash lamps in the second embodiment can also be changed as appropriate.

[0097] Furthermore, in the first embodiment described above, a filament-type halogen lamp HL was used as a continuous-lighting lamp that emitted light continuously for 1 second or more to preheat the semiconductor wafer W. However, the invention is not limited to this, and a discharge-type arc lamp (for example, a xenon arc lamp) or an LED lamp may be used as a continuous-lighting lamp instead of the halogen lamp HL to perform preheating.

[0098] Furthermore, in the first embodiment described above, a linear groove recess 101 is formed in the quartz plate 100 (300, 400), but it is not limited to a linear groove. Nor is it limited to a recess 101; any configuration that creates a gap between the semiconductor wafer W and the quartz plate 100 by being formed on the surface that contacts the semiconductor wafer W is acceptable. Therefore, it may be a convex portion instead of a recess.

[0099] Furthermore, in the first embodiment described above, the quartz plate 100 (300, 400) is formed in a disc shape, but it is not limited to this shape. In addition to the disc shape, it may be in various other shapes such as a triangular or square shape.

[0100] Furthermore, in the second embodiment described above, the flash lamps FL are arranged in two stages, upper and lower, but the invention is not limited to this. The first flash lamp and the second flash lamp may be arranged on the same plane. Also, the first flash lamp and the second flash lamp may be composed of the same flash lamp, as long as preheating by the first flash lamp and main heating by the second flash lamp can be achieved.

[0101] Furthermore, the substrates to be processed by the heat treatment apparatus 1 and heat treatment apparatus 2 are not limited to semiconductor wafers, but may also be glass substrates used in flat panel displays such as liquid crystal displays or substrates for solar cells. [Explanation of Symbols]

[0102] 1,2 Heat treatment equipment 3. Control Unit 4. Halogen heating section 5,250 Flash heating section 6 chambers 7 Holding part 10 Transfer mechanism 11 Transfer arm 12 Lift Pins 13 Horizontal movement mechanism 14. Lifting mechanism 20 Lower radiation thermometer 25 Upper radiation thermometer 43 Reflector 52 reflectors 63 Upper chamber window 64 Lower chamber window 65 Heat treatment space 71 Base Ring 72 Connecting part 74,374,474 susceptors 75,275,375 Retaining Plate 75a Holding surface 76 Through hole 77 Support pins 78 Opening 79,279 through holes 100,300,400 Quartz plate 100a Contact surface 101 Recess 107,109 Through holes 108 Opening 376 Quartz plate holding part 460 Quartz plate holding part FL Flash Lamp HL halogen lamp W Semiconductor wafer Wf semiconductor wafer surface Wb (back side of semiconductor wafer)

Claims

1. A heat treatment apparatus that heats a substrate by irradiating it with light, A chamber for housing the aforementioned substrate, Within the chamber, there is a holding portion for holding the substrate, A first flash light irradiation unit irradiates the substrate held in the holding unit with flash light to raise the temperature of the substrate from room temperature to a preheating temperature, A second flash light irradiation unit irradiates the substrate, which has been heated to the aforementioned preheating temperature, with flash light to raise the substrate to a processing temperature higher than the aforementioned preheating temperature. A heat treatment apparatus characterized by comprising the following:

2. In the heat treatment apparatus according to claim 1, A heat treatment apparatus characterized in that the flash light irradiation time of the first flash light irradiation unit and the second flash light irradiation unit is 0.1 milliseconds or more and 100 milliseconds or less.

3. In the heat treatment apparatus according to claim 1 or claim 2, A heat treatment apparatus characterized in that the interval between the emission of light from the first flash light irradiation unit and the emission of light from the second flash light irradiation unit is within 1 second.

4. A heat treatment method for heating a substrate by irradiating it with light, A first flash light irradiation step is performed in which, within a chamber containing the substrate, a first flash light is irradiated onto the substrate held by the holding part to raise the temperature of the substrate from room temperature to a preheating temperature, A second flash light irradiation step is performed by irradiating the substrate, which has been heated to the aforementioned preheating temperature, with a second flash light to raise the substrate to a processing temperature higher than the aforementioned preheating temperature. A heat treatment method characterized by comprising:

5. In the heat treatment method described in claim 4, A heat treatment method characterized in that the flash light irradiation time in the first flash light irradiation step and the second flash light irradiation step is 0.1 milliseconds or more and 100 milliseconds or less.

6. In the heat treatment method according to claim 4 or claim 5, A heat treatment method characterized in that the time between the completion of the first flash light irradiation step and the start of the second flash light irradiation step is within one second.

Images