Thermal treatment device

Abstract

To provide a thermal treatment device capable of heating a substrate up to a high temperature with high efficiency.SOLUTION: A thermal treatment device provides: a flush heating part that has a plurality of flush lamp onto an upper side of a chamber housing a semiconductor wafer, and an auxiliary heating part that has a plurality of laser diodes and a plurality of VCSELs (vertical resonator type surface light emission layer) to a lower side. At the time of a preheating of the semiconductor wafer, a light with a high directional pattern is radiated to a peripheral edge part of the semiconductor wafer from each VCSEL while performing an irradiation to a whole surface with a uniform irradiation distribution of the semiconductor wafer by an optical element emitted from the laser diode. Since the laser diode radiates a light of which a wavelength is shorter than 1 μm, and has a conventional higher strength light to the semiconductor wafer, it can heat the semiconductor wafer with high efficiency and to a high temperature. Also, by a light irradiation from each VCSEL, an in-surface temperature distribution of the semiconductor wafer can be uniformed.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a heat treatment apparatus for heating a substrate by irradiating the substrate with light, for example, a semiconductor wafer, a substrate for a liquid crystal display device, a substrate for a flat panel display (FPD), a substrate for an optical disk, a substrate for a magnetic disk, or a substrate for a solar cell. [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] Typically, a heat treatment apparatus that has a flash lamp above a chamber that holds a semiconductor wafer and a halogen lamp below it is used as an apparatus for performing such flash lamp annealing (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.

[0006] However, halogen lamps mainly radiate infrared light with a relatively long wavelength. In terms of the spectral absorptance of silicon semiconductor wafers, the absorptance of infrared light with a long wavelength of 1 μm or more is low in the low temperature range below 500°C. In other words, semiconductor wafers below 500°C do not absorb much infrared light irradiated from halogen lamps, so heating is inefficient in the initial stage of preheating.

[0007] For this reason, Patent Document 2 proposes preheating semiconductor wafers with LED (Light Emitting Diode) lamps instead of halogen lamps. LED lamps that emit light with a wavelength of 1 μm or less can efficiently heat even semiconductor wafers at relatively low temperatures. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2011-159713 A [Patent Document 2] JP 2022-106561 A Summary of the Invention [Problem to be solved by the invention]

[0009] However, because LED lamps have a relatively low output, it can be difficult to heat semiconductor wafers to the required preheating temperature. In order to heat semiconductor wafers to the required preheating temperature using LED lamps, it is necessary to install a large number of LED lamps, which increases costs and requires a large installation space.

[0010] The present invention has been made in view of the above problems, and an object of the present invention is to provide a heat treatment apparatus capable of efficiently heating a substrate to a high temperature. [Means for solving the problem]

[0011] In order to solve the above problems, a first aspect of the present invention is a heat treatment apparatus that heats a substrate by irradiating the substrate with light, the heat treatment apparatus comprising: a chamber for accommodating a substrate; a holding part for holding the substrate within the chamber; an auxiliary light source provided on one side of the chamber for irradiating light onto the substrate held by the holding part; and a flash lamp provided on the other side of the chamber for irradiating a flash of light onto the substrate preheated by the auxiliary light source, the auxiliary light source comprising a plurality of laser diodes.

[0012] In a second aspect, in the heat treatment apparatus according to the first aspect, an optical element is further provided that guides the light emitted from the plurality of laser diodes so that the entire surface of the substrate is irradiated with a uniform illuminance distribution.

[0013] In a third aspect, in the heat treatment apparatus according to the first or second aspect, the auxiliary light source further includes a plurality of vertical cavity surface emitting lasers.

[0014] In addition, according to a fourth aspect, in the heat treatment apparatus according to the third aspect, the heat treatment apparatus further includes a homogenizer that homogenizes the light emitted from each of the plurality of vertical cavity surface emitting lasers.

[0015] In a fifth aspect, in the heat treatment apparatus according to the third aspect, the plurality of vertical cavity surface emitting lasers are arranged in a ring shape so as to surround the optical element and irradiate light onto the peripheral portion of the substrate.

[0016] In a sixth aspect, in the heat treatment apparatus according to the fifth aspect, the auxiliary light source further includes an additional vertical cavity surface emitting laser arranged around the plurality of vertical cavity surface emitting lasers arranged in an annular shape and tilted so that the irradiation direction faces the substrate.

[0017] In addition, a seventh aspect is a heat treatment device according to any one of the first to fifth aspects, wherein the auxiliary light source includes a vertical cavity surface emitting laser that irradiates light of different wavelengths and a laser diode that irradiates light of different wavelengths. Effect of the Invention

[0018] According to the heat treatment apparatuses of the first to seventh aspects, the auxiliary light source for preheating the substrate before irradiation with flash light includes a plurality of laser diodes. The laser diodes irradiate light having a wavelength shorter than 1 μm and relatively high intensity, thereby efficiently heating the substrate to a high temperature.

[0019] In particular, in the heat treatment apparatus according to the fifth aspect, a plurality of vertical cavity surface emitting lasers are arranged in a ring shape surrounding the optical element and irradiate light onto the peripheral portion of the substrate, thereby complementing the heating of the peripheral portion of the substrate where a temperature drop occurs, and making the temperature distribution across the substrate uniform.

[0020] In particular, according to the heat treatment apparatus of the seventh aspect, the auxiliary light source includes a vertical cavity surface emitting laser that irradiates light of different wavelengths and a laser diode that irradiates light of different wavelengths, so that even if a film with low absorptivity for light of a specific wavelength is formed on part of the substrate, the entire surface of the substrate can be heated uniformly to improve the in-plane uniformity of the temperature distribution. [Brief description of the drawings]

[0021] [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. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 2 is a plan view showing an arrangement of optical elements and multiple VCSELs. [Figure 8] FIG. 2 is a diagram illustrating an optical element and light irradiation by a plurality of VCSELs. [Figure 9] FIG. 1 is a diagram showing the temperature distribution generated in a semiconductor wafer by irradiation with light from a laser diode. [Figure 10] FIG. 13 is a diagram showing the configuration of a heat treatment apparatus according to a second embodiment. [Figure 11] FIG. 11 is a plan view showing an example of an arrangement of a plurality of laser diodes and a plurality of VCSELs in the third embodiment. [Figure 12] FIG. 13 is a plan view showing an arrangement of an optical element and a plurality of VCSELs in a fourth embodiment. [Figure 13] 13 is a diagram illustrating an optical element according to a fourth embodiment and light irradiation from a plurality of VCSELs. FIG. [Figure 14] FIG. 13 is a diagram showing a configuration of a light source of an auxiliary heating unit in a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. In the following, expressions indicating relative or absolute positional relationships (e.g., "in one direction," "along one direction," "parallel," "orthogonal," "center," "concentric," "coaxial," etc.) not only strictly indicate the positional relationship, but also indicate a state in which the relative angle or distance is displaced within a range in which a tolerance or similar function is obtained, unless otherwise specified. Furthermore, expressions indicating an equal state (e.g., "same," "equal," "homogeneous," etc.) not only indicate a state in which the relative position is strictly equal quantitatively, but also indicate a state in which there is a difference in which a tolerance or similar function is obtained, unless otherwise specified. Furthermore, expressions indicating a shape (e.g., "circular," "square," "cylindrical," etc.) not only indicate a geometrically strict shape, but also indicate a shape within a range in which a similar effect is obtained, and may have, for example, unevenness or chamfering. Furthermore, each expression such as "comprises," "includes," "has," "includes," and "has" for a component is not an exclusive expression that excludes the presence of other components. In addition, the expression "at least one of A, B, and C" includes "A only," "B only," "C only," "any two of A, B, and C," and "all of A, B, and C."

[0023] First Embodiment 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.

[0024] 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 an auxiliary heating unit 4 that includes a plurality of VCSELs (Vertical Cavity Surface Emitting Lasers) 45 and a plurality of laser diodes 47. The flash heating unit 5 is provided on the upper side of the chamber 6, and the auxiliary 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 auxiliary heating unit 4, the flash heating unit 5, and the chamber 6 to perform heat treatment of the semiconductor wafer W.

[0025] 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 forming 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 forming 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 auxiliary heating unit 4 into the chamber 6.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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).

[0031] 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.

[0032] 2 is a perspective view showing the overall appearance of the holder 7. 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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. 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.

[0046] 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.

[0047] The auxiliary heating unit 4 is provided on the opposite side of the chamber 6 from the flash heating unit 5, i.e., below the chamber 6. The auxiliary heating unit 4 includes a cabinet 48 incorporating a plurality of laser diodes 47, an optical element 49, and a plurality of VCSELs 45. The auxiliary heating unit 4 is an auxiliary light source that heats the semiconductor wafer W by irradiating light from below the chamber 6 into a heat treatment space 65 via a lower chamber window 64 using the plurality of laser diodes 47 and the plurality of VCSELs 45.

[0048] 7 is a plan view showing the arrangement of the optical element 49 and the multiple VCSELs 45. The optical element 49 of this embodiment is a quartz member having a roughly cylindrical shape, and is a diffractive optical element (DOE) that utilizes the diffraction phenomenon of light. The optical element 49 is disposed below the center of the semiconductor wafer W held by the holder 7. Meanwhile, the multiple VCSELs 45 are disposed in a circular ring shape so as to surround the periphery of the optical element 49. The number of VCSELs 45 disposed in a circular ring shape can be any appropriate number. The multiple VCSELs 45 are disposed below the peripheral portion of the semiconductor wafer W held by the holder 7.

[0049] FIG. 8 is a diagram showing a schematic diagram of light irradiation by an optical element 49 and a plurality of VCSELs 45. The lower end surface of the optical element 49 and a cabinet 48 are connected by an optical fiber 46. A plurality of laser diodes 47 are provided inside the cabinet 48 (FIG. 1). The laser diode 47 is an element that causes laser oscillation by passing a current through a semiconductor, and is also called a semiconductor laser. The laser diode 47 has a high output conversion efficiency, is capable of emitting light with a higher intensity than an LED, and has a long life. The laser light emitted from the plurality of laser diodes 47 is collected and combined inside the cabinet 48 and is guided to the optical element 49 by the optical fiber 46.

[0050] Generally, laser light has a high directivity, and the laser light emitted from the multiple laser diodes 47 and incident on the optical element 49 also has the property of traveling straight without spreading. The optical element 49 is a diffractive optical element that diffracts incident light by performing fine processing on a quartz member and outputs light of various patterns. The optical element 49 spatially branches the laser light that is guided by the optical fiber 46 and incident on the lower end face and emits it so as to spread from the upper end face. In other words, the optical element 49 diffracts the highly directional laser light guided from the cabinet 48 by the optical fiber 46 to make it a light that travels in a spreading manner. As a result, the light emitted from the upper end face of the optical element 49 is irradiated onto the entire lower face of the semiconductor wafer W held by the holding unit 7.

[0051] Furthermore, the intensity distribution of the laser light emitted from the laser diode 47 and guided by the optical fiber 46 is close to a Gaussian distribution. That is, the intensity of the laser light is highest near the center of the optical axis, and decreases with increasing distance from the optical axis. The optical element 49 also has the function of homogenizing the intensity distribution of the incident light. Therefore, the intensity distribution of the laser light incident on the optical element 49 is homogenized, and light with a uniform illuminance distribution is irradiated from the optical element 49 onto the underside of the semiconductor wafer W.

[0052] On the other hand, the VCSEL (Vertical Cavity Surface Emitting Laser) 45 is a type of semiconductor laser that emits light in a direction perpendicular to the surface of the semiconductor substrate. The VCSEL 45 is capable of emitting light of a relatively high intensity and emits light with high directivity. In other words, the irradiation area of ​​the VCSEL 45 is small. The multiple VCSELs 45 are disposed below the peripheral portion of the semiconductor wafer W held by the holder 7, and each VCSEL 45 emits light vertically upward. Therefore, while the optical element 49 irradiates the entire lower surface of the semiconductor wafer W with light, the VCSELs 45 irradiate light only to the peripheral portion of the semiconductor wafer W.

[0053] In this embodiment, the laser diode 47 emits light having a wavelength of 960 nm or more and 985 nm or less. The VCSEL 45 emits light having a wavelength of 930 nm or more and 940 nm or less. In addition, both the laser diode 47 and the VCSEL 45 are continuously lit lamps that emit light continuously for at least one second or more.

[0054] 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.

[0055] 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 auxiliary heating unit 4, the flash heating unit 5, and the chamber 6 due to the thermal energy generated from the laser diode 47, the VCSEL 45, and the flash lamps FL during the heat treatment of the semiconductor wafer W. For example, a water-cooled pipe (not shown) is provided in the wall of the chamber 6. The auxiliary 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.

[0056] Next, the processing operation in the heat treatment apparatus 1 will be described. Here, a typical heat treatment operation for a normal semiconductor wafer (product wafer) W that will become a product will be described. The semiconductor wafer W to be processed is a silicon (Si) semiconductor substrate into which impurities have been implanted by ion implantation as a previous process. The impurities are activated by an annealing process performed by the heat treatment apparatus 1. The processing procedure for the semiconductor wafer W, which will be described below, proceeds as the control unit 3 controls each operating mechanism of the heat treatment apparatus 1.

[0057] 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.

[0058] Next, the gate valve 185 is opened to open the transport opening 66, and the semiconductor wafer W to be treated is carried into the heat treatment space 65 in the chamber 6 through the transport opening 66 by a transport robot outside the apparatus. At this time, there is a risk that the atmosphere outside the apparatus may be drawn in with the carrying in of the semiconductor wafer W, 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 entrainment of such external atmosphere.

[0059] 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.

[0060] 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, and the semiconductor wafer W is transferred from the transfer mechanism 10 to the susceptor 74 of the holder 7, where it is 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 the surface on which the pattern has been formed and the impurities have been implanted as the upper surface. A predetermined gap is formed between the back surface (the main surface opposite to the front surface) of the semiconductor wafer W supported by the plurality of substrate support pins 77 and the holding surface 75a of the holding plate 75. The pair of transfer arms 11 that descend to below the susceptor 74 are retreated to a retreat position, that is, inside the recess 62, by the horizontal movement mechanism 13.

[0061] 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 auxiliary heating unit 4 irradiates the semiconductor wafer W with light to start preheating (assisted heating). Laser light emitted from a plurality of laser diodes 47 is collected and combined in the cabinet 48 and guided to the lower end surface of the optical element 49 by the optical fiber 46. The optical element 49 diffracts the laser light incident from the lower end surface to homogenize the intensity distribution, and also expands the traveling direction and emits the light from the upper end surface. The light emitted from the optical element 49 passes through the lower chamber window 64 and the susceptor 74 made of quartz, and is irradiated with a uniform illuminance distribution over the entire lower surface of the semiconductor wafer W.

[0062] However, even if the entire bottom surface of the semiconductor wafer W is irradiated with light from the laser diode 47 with a uniform illuminance distribution, a non-uniform temperature distribution occurs in the semiconductor wafer W as shown in Fig. 9. That is, a temperature distribution occurs in which the temperature is relatively lower at the periphery compared to the center of the semiconductor wafer W. The reason why the temperature distribution becomes non-uniform despite the irradiation with light with a uniform illuminance distribution is that the amount of heat dissipated outward is greater at the periphery of the semiconductor wafer W compared to the center, and thus a temperature drop is more likely to occur.

[0063] For this reason, in the first embodiment, a plurality of VCSELs 45 are provided, and light is irradiated from these to the peripheral portion of the semiconductor wafer W. The VCSELs 45 irradiate light that is relatively strong and highly directional to the peripheral portion of the semiconductor wafer W. As a result, light is irradiated from the plurality of VCSELs 45 only to the peripheral portion of the semiconductor wafer W where a relative temperature drop occurs, eliminating the temperature drop in the peripheral portion and achieving a uniform temperature distribution over the entire surface of the semiconductor wafer W.

[0064] The semiconductor wafer W is preheated by being irradiated with light from the multiple laser diodes 47 and the multiple VCSELs 45, and the temperature of the semiconductor wafer W increases. The temperature of the semiconductor wafer W, which increases due to the light irradiation from the auxiliary heating unit 4, is measured by the 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 laser diode 47 and the VCSEL 45 while monitoring whether the temperature of the semiconductor wafer W, which increases due to the light irradiation from the auxiliary heating unit 4, has reached a predetermined preheating temperature T1. That is, the control unit 3 feedback-controls the output of the laser diode 47 and the VCSEL 45 based on the measured value by the radiation thermometer 20 so that the temperature of the semiconductor wafer W becomes the preheating temperature T1. The preheating temperature T1 is set to about 200°C to 800°C, preferably about 350°C to 600°C (600°C in this embodiment), at which there is no risk of impurities added to the semiconductor wafer W being diffused by heat.

[0065] 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 laser diode 47 and the VCSEL 45 to maintain the temperature of the semiconductor wafer W at approximately the preheating temperature T1.

[0066] When a predetermined time has elapsed since the temperature of the semiconductor wafer W reached the preheating temperature T1, 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. At this time, part of the flash light emitted from the flash lamps FL heads directly into the chamber 6, and the other part heads into the chamber 6 after being reflected by the reflector 52, and the semiconductor wafer W is flash-heated by the irradiation of these flash lights.

[0067] Since flash heating is performed by irradiating a flash light (light flash) from the flash lamp FL, the surface temperature of the semiconductor wafer W can be raised in a short time. That is, the flash light irradiated from the flash lamp FL is an extremely short and strong flash with an 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 flash-heated by the irradiation of the flash light from the flash lamp FL instantaneously rises to a processing temperature T2 of 1000°C or more, and the impurities implanted in the semiconductor wafer W are activated, and then the surface temperature drops rapidly. In this way, the heat treatment device 1 can raise and lower the surface temperature of the semiconductor wafer W in an extremely short time, so that the impurities can be activated while suppressing the diffusion of the impurities implanted in the semiconductor wafer W due to heat. The time required for activating the impurities is extremely short compared to the time required for their thermal diffusion, so that the activation is completed even in a short time of about 0.1 milliseconds to 100 milliseconds in which diffusion does not occur.

[0068] After the flash heating process is completed, the light irradiation from the auxiliary heating unit 4 is also stopped 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, completing the heat treatment of the semiconductor wafer W.

[0069] In the first embodiment, during preheating of the semiconductor wafer W, the laser diodes 47 irradiate the entire surface of the semiconductor wafer W with light with a uniform illuminance distribution, while the VCSELs 45 irradiate the peripheral portion of the semiconductor wafer W with light. The laser diodes 47 irradiate the semiconductor wafer W with light having a wavelength shorter than 1 μm. In terms of the spectral absorptance of the silicon semiconductor wafer W, the absorptance of infrared light having a wavelength of more than 1 μm is low in the low temperature range of 500° C. or less, but the absorptance of light having a wavelength of 1 μm or less is relatively high. That is, even in the low temperature range of 500° C. or less, the semiconductor wafer W absorbs the light irradiated from the laser diodes 47 well. Therefore, even when the temperature of the semiconductor wafer W is 500° C. or less in the initial stage of preheating, the semiconductor wafer W can be efficiently heated by the laser diodes 47.

[0070] Furthermore, the laser diode 47 emits light with a higher intensity than an LED. Therefore, the temperature of the semiconductor wafer W can be raised to a desired preheating temperature T1 by the laser diode 47. That is, the semiconductor wafer W can be efficiently heated to a high temperature by the light irradiation from the laser diode 47.

[0071] However, even if light is irradiated from the laser diode 47 with a uniform illuminance distribution over the entire underside of the semiconductor wafer W, a non-uniform temperature distribution occurs in which the temperature of the peripheral portion of the semiconductor wafer W, which cools easily, is lower than the temperature of the central portion. Therefore, highly directional light is irradiated onto the peripheral portion of the semiconductor wafer W from a plurality of VCSELs 45 arranged in an annular shape below the peripheral portion of the semiconductor wafer W. The VCSELs 45 can also emit light with a relatively high intensity, so that it is possible to supplement the heating of the peripheral portion of the semiconductor wafer W where a drop in temperature occurs, and it is possible to make the in-plane temperature distribution of the semiconductor wafer W uniform.

[0072] <Second embodiment> Next, a second embodiment of the present invention will be described. Fig. 10 is a diagram showing the configuration of a heat treatment apparatus according to the second embodiment. In the second embodiment, a homogenizer 43 is provided to homogenize the distribution of light emitted from each of a plurality of VCSELs 45.

[0073] The homogenizer 43 is a quartz member provided between the VCSEL 45 and the lower chamber window 64 of the chamber 6. The homogenizer 43 is also a diffractive optical element, and homogenizes the intensity distribution of the light emitted from the corresponding VCSEL 45.

[0074] The VCSEL 45 is also a type of semiconductor laser that emits light with relatively high directivity, and the intensity distribution of the light is close to a Gaussian distribution. For this reason, when the semiconductor wafer W is directly irradiated with light from the VCSEL 45, there is a risk that areas of high and low illuminance will appear locally on the irradiated surface of the semiconductor wafer W, resulting in uneven illuminance. By homogenizing the intensity distribution of the light emitted from the VCSEL 45 using the homogenizer 43, the uneven illuminance on the irradiated surface of the semiconductor wafer W is eliminated, and the illuminance distribution becomes uniform. As a result, the in-plane temperature distribution of the semiconductor wafer W during preheating also becomes more uniform.

[0075] The configuration of the heat treatment apparatus of the second embodiment is the same as that of the heat treatment apparatus 1 of the first embodiment, except for the provision of the homogenizer 43. The processing procedure of the semiconductor wafer W in the heat treatment apparatus of the second embodiment is also the same as that of the first embodiment.

[0076] <Third embodiment> Next, a third embodiment of the present invention will be described. In the third embodiment, the semiconductor wafer W is directly irradiated with light from a plurality of laser diodes 47 without providing an optical element 49.

[0077] 11 is a plan view showing an example of an arrangement of a plurality of laser diodes 47 and a plurality of VCSELs 45 in the third embodiment. The plurality of laser diodes 47 are arranged in a planar manner with uniform density in a circular region below the center of the semiconductor wafer W held by the holder 7. The plurality of VCSELs 45 are arranged with uniform density in an annular region surrounding the periphery of the circular region in which the plurality of laser diodes 47 are arranged. The annular region in which the plurality of VCSELs 45 are arranged is below the peripheral portion of the semiconductor wafer W. That is, in the auxiliary heating unit 4 of the third embodiment, the plurality of laser diodes 47 are arranged in the central portion, and the plurality of VCSELs 45 are arranged in the peripheral portion.

[0078] Although the laser diode 47 emits a highly directional laser light, by arranging a plurality of laser diodes 47 in a circular area at a uniform density as shown in FIG. 11, the light can be irradiated to the entire lower surface of the semiconductor wafer W. However, even if a plurality of laser diodes 47 are arranged in a circular area at a uniform density, an uneven temperature distribution occurs in which the temperature of the peripheral portion of the semiconductor wafer W is lower than that of the central portion, as in the first embodiment. For this reason, a plurality of VCSELs 45 are provided to face the peripheral portion of the semiconductor wafer W, and light is irradiated from them to the peripheral portion of the semiconductor wafer W. As a result, the peripheral portion of the semiconductor wafer W, which is prone to low temperature, is strongly heated, and the temperature drop in the peripheral portion is eliminated, making it possible to make the in-plane temperature distribution of the semiconductor wafer W uniform.

[0079] The remaining configuration of the third embodiment is the same as that of the first embodiment. In addition, the processing procedure of the semiconductor wafer W in the third embodiment is also the same as that in the first embodiment.

[0080] <Fourth embodiment> Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, an additional VCSEL 45 is provided in addition to the multiple VCSELs 45 of the first embodiment.

[0081] Fig. 12 is a plan view showing the arrangement of an optical element 49 and a plurality of VCSELs 45 in the fourth embodiment. Fig. 13 is a schematic diagram showing light irradiation from an optical element 49 and a plurality of VCSELs 45 in the fourth embodiment. In the fourth embodiment, additional VCSELs 45 are arranged around the plurality of VCSELs 45 arranged in an annular shape in the first embodiment. The additional plurality of VCSELs 45 are provided at an angle in a region outside the semiconductor wafer W held by the holder 7.

[0082] More specifically, similarly to the first embodiment, a plurality of VCSELs 45 are arranged in an annular shape below the peripheral edge of the semiconductor wafer W held by the holder 7. Furthermore, a plurality of additional VCSELs 45 are arranged around the plurality of VCSELs 45 arranged in an annular shape in a region outside the semiconductor wafer W. The plurality of additional VCSELs 45 provided in the region outside the semiconductor wafer W are arranged at an angle such that their irradiation direction faces the underside of the semiconductor wafer W. The configuration of the fourth embodiment and the processing procedure for the semiconductor wafer W are the same as those of the first embodiment, except for the provision of the plurality of additional VCSELs 45.

[0083] In the fourth embodiment, similarly to the first embodiment, the entire surface of the semiconductor wafer W is irradiated with light with a uniform illuminance distribution by the multiple laser diodes 47, while the peripheral portion of the semiconductor wafer W is irradiated with light from the multiple VCSELs 45 arranged in an annular shape. This makes it possible to strongly heat the peripheral portion of the semiconductor wafer W, which is prone to temperature drops, by irradiating the peripheral portion with highly directional light from the VCSELs 45, and to uniformize the in-plane temperature distribution of the semiconductor wafer W. Furthermore, in the fourth embodiment, the semiconductor wafer W can be heated to a high temperature more efficiently by performing additional light irradiation on the surface of the semiconductor wafer W from the additional VCSELs 45.

[0084] <Fifth embodiment> Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, a fiber laser is used in which laser light emitted from a laser diode 47 is amplified using an optical fiber doped with a rare earth element.

[0085] FIG. 14 is a diagram showing the configuration of the light source of the auxiliary heating unit in the fifth embodiment. In FIG. 14, the same elements as those in the first embodiment are given the same reference numerals. A cabinet 48 is provided with a plurality of laser diodes 47, a pump combiner 44, and a rare-earth doped fiber 41. The rare-earth doped fiber 41 is an optical fiber whose core is doped with a rare earth. For example, ytterbium (Yb), neodymium (Nd), thulium (Tm), and erbium (Er) are used as the doped rare earth. A double clad is provided on the outside of the core. In addition, mirrors or fiber Bragg gratings (FBGs) (not shown) are provided at both ends of the rare-earth doped fiber 41.

[0086] The laser light emitted from the multiple laser diodes 47 is combined by the pump combiner 44. The combined laser light is incident on the rare-earth doped fiber 41 as excitation light. The excitation light excites the doped rare-earth element, which causes the laser light to be emitted. In other words, the laser light is amplified. The emitted laser light is guided to the optical element 49 by the optical fiber 46. Then, as in the first embodiment, the light emitted from the upper end surface of the optical element 49 is irradiated onto the lower surface of the semiconductor wafer W. In a fiber laser such as that in the fifth embodiment, excitation and emission are performed in a thin core in the rare-earth doped fiber 41, so that the amplification efficiency of the laser light is good.

[0087] <Modification> 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 auxiliary heating unit 4 is provided with the laser diode 47 and the VCSEL 45. Instead, the auxiliary heating unit 4 may be provided with only a plurality of laser diodes 47. In this case, the semiconductor wafer W is preheated only by the plurality of laser diodes 47. The laser diode 47 irradiates the semiconductor wafer W with light having a wavelength shorter than 1 μm, and the light is well absorbed by the semiconductor wafer W at a relatively low temperature in the initial stage of preheating. The laser diode 47 also emits light with a relatively high intensity. That is, the laser diode 47 can heat the semiconductor wafer W to a high temperature more efficiently than a conventional halogen lamp.

[0088] When the auxiliary heating unit 4 is provided with only the laser diode 47 without providing the VCSEL 45, the optical element 49 may be provided as in the first embodiment, or a plurality of laser diodes 47 may be arranged in a planar manner as in the third embodiment. When the optical element 49 is provided, it is preferable to diffract the incident light so as to provide an intensity distribution in which a relatively strong light is irradiated onto the peripheral edge of the semiconductor wafer W. This makes it possible to make the in-plane temperature distribution of the semiconductor wafer W uniform.

[0089] In the above embodiment, the wavelength of the light irradiated from the multiple laser diodes 47 and the multiple VCSELs 45 is a single wavelength. Alternatively, at least one of the multiple laser diodes 47 and the multiple VCSELs 45 may irradiate light of different wavelengths. That is, the auxiliary heating unit 4 may be provided with laser diodes 47 that irradiate light of different wavelengths and / or VCSELs 45 that irradiate light of different wavelengths. When the multiple laser diodes 47 and the multiple VCSELs 45 irradiate light of a single wavelength, if a film with a low absorptance for light of that wavelength is formed on a part of the semiconductor wafer W, the temperature of only that part may become relatively low, and the in-plane uniformity of the temperature distribution may be impaired. If the multiple laser diodes 47 and / or the multiple VCSELs 45 irradiate light of multiple wavelengths, the entire surface of the semiconductor wafer W can be uniformly heated to improve the in-plane uniformity of the temperature distribution, even if a film with a low absorptance for light of a specific wavelength is formed on a part of the semiconductor wafer W.

[0090] Furthermore, the optical element 49 is not limited to a diffractive optical element, but may be, for example, an element that adjusts the optical path by refraction.

[0091] Moreover, the optical element 49 may not be provided, and the light guided by the optical fiber 46 may be directly irradiated onto the semiconductor wafer W.

[0092] In addition, in each of the above embodiments, the auxiliary heating unit 4 is provided below the chamber 6, but this is not limiting, and the auxiliary heating unit 4 including a plurality of laser diodes 47 and a plurality of VCSELs 45 may be provided above the chamber 6. In this case, the semiconductor wafer W is preheated by light irradiation from the laser diodes 47 and the VCSELs 45 from above the chamber 6.

[0093] In addition, in the above embodiment, the VCSEL 45 is disposed so as to face the peripheral portion of the semiconductor wafer W, but this is not limited to this, and the VCSEL 45 may be disposed so as to face a portion of the semiconductor wafer W where a temperature drop is likely to occur during preheating.

[0094] In the above embodiment, the flash heating unit 5 is provided with 30 flash lamps FL, but the number of flash lamps FL is not limited to this and may be any number. In addition, the flash lamps FL are not limited to xenon flash lamps and may be krypton flash lamps. [Explanation of symbols]

[0095] 1 Heat treatment equipment 3. Control Unit 4 Auxiliary heating section 5 Flash heating section 6 Chambers 7 Holding part 10 Transfer mechanism 20 Radiation thermometer 43 Homogenizer 45 VCSEL 47 Laser Diode 49 Optical Elements 65 Heat Treatment Space 74 Susceptor FL Flash 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; an auxiliary light source provided on one side of the chamber and configured to irradiate light onto the substrate held by the holder; a flash lamp provided on the other side of the chamber and configured to irradiate the substrate preheated by the auxiliary light source with a flash of light; Equipped with The auxiliary light source is a heat treatment apparatus having a plurality of laser diodes.

2. 2. The heat treatment apparatus according to claim 1, The heat treatment apparatus further comprises an optical element that guides the light emitted from the plurality of laser diodes so that the entire surface of the substrate is irradiated with a uniform illuminance distribution.

3. 3. The heat treatment apparatus according to claim 2, The auxiliary light source further comprises a plurality of vertical cavity surface emitting lasers.

4. 4. The heat treatment apparatus according to claim 3, The heat treatment apparatus further comprises a homogenizer for homogenizing the light emitted from each of the plurality of vertical cavity surface emitting lasers.

5. 4. The heat treatment apparatus according to claim 3, The vertical cavity surface emitting lasers are arranged in a ring shape surrounding the optical element and irradiate the peripheral portion of the substrate with light.

6. 6. The heat treatment apparatus according to claim 5, The heat treatment apparatus further includes an auxiliary light source having an additional vertical cavity surface emitting laser disposed around the plurality of vertical cavity surface emitting lasers arranged in an annular manner and tilted so that the irradiation direction faces the substrate.

7. 4. The heat treatment apparatus according to claim 3, The heat treatment device, wherein the auxiliary light source includes a vertical cavity surface emitting laser that irradiates light of different wavelengths and a laser diode that irradiates light of different wavelengths.

Images