Heat treatment apparatus and heat treatment method

Abstract

The present invention provides a heat treatment apparatus and a heat treatment method that can prevent the substrate from jumping during flash light irradiation. [Solution] A support ring 77, which is a convex part of an annular quartz having a diameter smaller than the diameter of the semiconductor wafer W, is erected on the upper surface of the holding plate 75 of the susceptor 74. The semiconductor wafer W is heated by irradiating the surface of the semiconductor wafer W supported by the support ring 77 with flash light. When the semiconductor wafer W is placed on the support ring 77, a sealed space 96 is formed surrounded by the upper surface of the holding plate 75, the lower surface of the semiconductor wafer W, and the inner wall surface of the support ring 77. When flash light is irradiated, the pressure difference that arises between the space 95 above the semiconductor wafer W and the sealed space 96 causes a downward force to act on the surface of the semiconductor wafer W, preventing the semiconductor wafer W from jumping.

Description

Technical Field

[0001] The present invention relates to a heat treatment apparatus and a heat treatment method for heating a disk-shaped substrate by irradiating the substrate with flash light. The substrates to be processed include, for example, semiconductor wafers, substrates for liquid crystal display devices, substrates for flat panel displays (FPDs), substrates for optical disks, substrates for magnetic disks, or substrates for solar cells.

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 "flash lamp" when referring to a xenon flash lamp) to irradiate flash light on the surface of a semiconductor wafer, thereby raising the temperature of only the surface of the semiconductor wafer in an extremely short time (several milliseconds or less).

[0003] The emission spectral distribution of a xenon flash lamp is from the ultraviolet region to the near-infrared region, and the wavelength is shorter than that of a conventional halogen lamp, and almost coincides with the fundamental absorption band of a silicon semiconductor wafer. Therefore, when flash light is irradiated from a xenon flash lamp to a semiconductor wafer, there is little transmitted light and the semiconductor wafer can be rapidly heated. It has also 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 the ion implantation method, 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 flash lamp annealing, a flash of light with extremely high energy is instantaneously shone onto the surface of the semiconductor wafer. As a result, the surface temperature of the semiconductor wafer rises rapidly in an instant, while the temperature of the back surface does not rise as much. This causes rapid thermal expansion only on the surface of the semiconductor wafer, deforming the wafer so that its top surface becomes convex. Then, in the next instant, the semiconductor wafer deforms again, so that its bottom surface becomes convex due to the recoil. Consequently, the wafer vibrates violently on the susceptor supporting it, causing the semiconductor wafer to jump using the susceptor's plate and support pins as a base. When the semiconductor wafer jumps off the susceptor and lands back on it, it comes into contact with the support pins, which can cause scratches on the back surface of the wafer, or in the worst case, the semiconductor wafer or support pins to break.

[0006] Therefore, Patent Document 1 discloses a technology that suppresses the jumping of a semiconductor wafer by supporting the susceptor with an elastic member such as an air spring, and absorbing and mitigating the force when the semiconductor wafer deforms rapidly during flash light irradiation with the air spring. Furthermore, Patent Document 2 discloses a technology that prevents wafer breakage by mitigating the impact during fall by receiving the semiconductor wafer that jumped from the susceptor during flash light irradiation with a tapered surface. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2016-219719 [Patent Document 2] Japanese Patent Publication No. 2014-120497 [Overview of the project] [Problems that the invention aims to solve]

[0008] Although the technologies disclosed in Patent Documents 1 and 2 can prevent semiconductor wafer cracking to some extent, there is a need for a simpler configuration that suppresses semiconductor wafer jumping and prevents wafer cracking.

[0009] 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 can prevent the substrate from jumping when irradiated with flash light. [Means for solving the problem]

[0010] To solve the above problems, a first aspect of the present invention is a heat treatment apparatus for heating a disc-shaped substrate by irradiating the substrate with a flash of light, comprising: a chamber for housing the substrate; a susceptor for holding the substrate within the chamber; and a flash lamp for irradiating the substrate held by the susceptor with a flash of light, wherein the susceptor includes a flat quartz holding plate and an annular quartz convex portion erected on the upper surface of the holding plate and having a diameter smaller than the diameter of the substrate.

[0011] Furthermore, in the second embodiment, when the substrate is placed on the convex portion of the heat treatment apparatus according to the first embodiment, a sealed space is formed surrounded by the upper surface of the holding plate, the lower surface of the substrate, and the convex portion.

[0012] Furthermore, the third embodiment is a heat treatment apparatus according to the second embodiment, further comprising a depressurization mechanism for reducing the pressure of the sealed space.

[0013] Furthermore, the fourth embodiment is a heat treatment apparatus according to the third embodiment, wherein the pressure reduction mechanism includes an exhaust port provided in the holding plate and an ejector that applies negative pressure to the exhaust port.

[0014] Furthermore, the fifth embodiment is a heat treatment apparatus according to any of the first to fourth embodiments, wherein a plurality of annular convex portions are arranged on the upper surface of the holding plate.

[0015] Furthermore, the sixth embodiment is a heat treatment apparatus according to the fifth embodiment, wherein a plurality of annular convex portions of different diameters are arranged concentrically on the upper surface of the holding plate.

[0016] Furthermore, the seventh embodiment further comprises a continuous-lighting lamp that preheats the substrate held in the susceptor by irradiating it with light before irradiating it with the flash light, in a heat treatment apparatus according to any of the first to sixth embodiments.

[0017] Furthermore, an eighth aspect is a heat treatment method for heating a disc-shaped substrate by irradiating the substrate with flash light, comprising a holding step of holding the substrate in a susceptor within a chamber, and a flash light irradiation step of irradiating the substrate held in the susceptor with flash light from a flash lamp, wherein the susceptor includes a flat plate-shaped quartz holding plate and an annular convex portion of quartz erected on the upper surface of the holding plate and having a diameter smaller than the diameter of the substrate, and in the holding step, the substrate is placed on the convex portion.

[0018] Furthermore, in the ninth embodiment, in the heat treatment method according to the eighth embodiment, when the substrate is placed on the convex portion in the holding step, a sealed space is formed surrounded by the upper surface of the holding plate, the lower surface of the substrate, and the convex portion.

[0019] Furthermore, the tenth embodiment further comprises a depressurization step of reducing the pressure in the sealed space, in the heat treatment method according to the ninth embodiment.

[0020] Furthermore, the 11th embodiment is a heat treatment method according to the 10th embodiment, wherein the depressurization step includes a step of depressurizing the inside of the chamber before the substrate is placed on the convex portion, and a step of restoring pressure to the inside of the chamber after the substrate is placed on the convex portion.

[0021] Moreover, a twelfth aspect is the heat treatment method according to any one of the eighth to eleventh aspects, further comprising a preheating step of preheating the substrate by irradiating light from a continuously lit lamp onto the substrate held by the susceptor before the flash light irradiation step.

Advantages of the Invention

[0022] According to the heat treatment apparatus according to the first to seventh aspects, the susceptor that holds the substrate in the chamber includes a flat quartz holding plate and an annular quartz convex portion that stands on the upper surface of the holding plate and has a diameter smaller than the diameter of the substrate. Therefore, a pressure difference occurs between the upper and lower sides of the substrate during flash light irradiation, and a force that presses from above acts on the upper surface of the substrate, preventing the substrate from jumping during flash light irradiation.

[0023] In particular, according to the heat treatment apparatus according to the third aspect, since it includes a decompression mechanism for decompressing the sealed space below the substrate, a pressure difference can be surely generated between the upper and lower sides of the substrate.

[0024] According to the heat treatment method according to the eighth to twelfth aspects, the susceptor that holds the substrate in the chamber includes a flat quartz holding plate and an annular quartz convex portion that stands on the upper surface of the holding plate and has a diameter smaller than the diameter of the substrate. Therefore, a pressure difference occurs between the upper and lower sides of the substrate during flash light irradiation, and a force that presses from above acts on the upper surface of the substrate, preventing the substrate from jumping during flash light irradiation.

[0025] In particular, according to the heat treatment method according to the tenth aspect, since it includes a decompression step for decompressing the sealed space below the substrate, a pressure difference can be surely generated between the upper and lower sides of the substrate.

Brief Description of the Drawings

[0026] [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 appearance of the holding part. [Figure 3] This is a plan view of the susceptor. [Figure 4] This is a side view of a susceptor that holds a semiconductor wafer. [Figure 5] This is a plan view of the transfer mechanism. [Figure 6] This is a side view of the transfer mechanism. [Figure 7] This is a plan view showing the arrangement of multiple halogen lamps. [Figure 8] Figure 1 is a flowchart showing the processing procedure of the first embodiment of the heat treatment apparatus. [Figure 9] This diagram schematically illustrates the phenomena that occur when a flash of light is applied. [Figure 10] This is a flowchart showing the processing procedure of the second embodiment. [Figure 11] This diagram schematically shows the state in which the lift pins support the semiconductor wafer. [Figure 12] This diagram schematically shows a state in which the pressure inside the chamber is reduced to below atmospheric pressure while the lift pins support the semiconductor wafer. [Figure 13] This diagram schematically shows a semiconductor wafer placed on a support ring. [Figure 14] This diagram schematically shows the state in which the chamber has been restored to its original pressure. [Figure 15] This figure shows an example of a depressurization mechanism for reducing the pressure in a sealed space. [Figure 16] This is a flowchart showing the processing procedure of the third embodiment. [Figure 17] This is a plan view showing other examples of support ring configurations. [Figure 18] This is a plan view showing other examples of support ring configurations. [Figure 19] This is a plan view showing other examples of support ring configurations. [Figure 20] This is a plan view showing other examples of support ring configurations. [Modes for carrying out the invention]

[0027] Embodiments of the present invention will be described in detail below 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.) shall, unless otherwise specified, not only strictly represent the positional relationship but also represent a state in which there is a relative displacement in terms of angle or distance within a tolerance or a range in which a similar level of function can be obtained. Similarly, expressions indicating equality (e.g., "identical," "equal," "homogeneous," etc.) shall, unless otherwise specified, not only represent a state in which there is a quantitatively strictly equal state but also represent a state in which there is a difference in which a tolerance or a similar level of function can be obtained. Furthermore, expressions indicating shape (e.g., "circular," "square," "cylindrical," etc.) shall, unless otherwise specified, not only strictly represent the geometrically precise shape but also represent a shape within a range in which a similar level of effect can be obtained, and may have, for example, irregularities or chamfers. Additionally, expressions such as "equipped," "possessing," "containing," "having," etc., for a component are not exclusive expressions that exclude the existence of other components. Furthermore, 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."

[0028] <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.

[0029] The heat treatment apparatus 1 comprises a chamber 6 for housing a semiconductor wafer W, a flash heating unit 5 incorporating multiple flash lamps FL, and a halogen heating unit 4 incorporating multiple halogen lamps HL. The flash heating unit 5 is located on the upper side of the chamber 6, while 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.

[0030] Chamber 6 is constructed by mounting quartz chamber windows on the top and bottom of a cylindrical chamber side section 61. The chamber side section 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 forms 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 section 5 into chamber 6. Similarly, the lower chamber window 64, which forms 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 section 4 into chamber 6.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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 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.

[0035] 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).

[0036] 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.

[0037] 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.

[0038] The exhaust unit 190 includes a vacuum pump. By operating the exhaust unit 190 to exhaust the gas from the heat treatment space 65 without supplying gas from the gas supply port 81, the pressure inside the chamber 6 can be reduced to below atmospheric pressure. In other words, the exhaust unit 190 also functions as a pressure reduction unit.

[0039] 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.

[0040] 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.

[0041] 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. Figure 4 is a side view of the susceptor 74 that holds the semiconductor wafer W. The susceptor 74 comprises a holding plate 75, a guide ring 76, and a support ring 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. That is, the holding plate 75 has a larger planar size than the semiconductor wafer W.

[0042] A guide ring 76 is installed on the upper peripheral edge of the retaining 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, if 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 tapered so as to widen upward from the retaining plate 75. The guide ring 76 is made of quartz, the same material as the retaining plate 75. The guide ring 76 may be welded to the upper surface of the retaining plate 75, or it may be fixed to the retaining plate 75 by a separately processed pin or the like. Alternatively, the retaining plate 75 and the guide ring 76 may be manufactured as a single integrated member.

[0043] The area of ​​the upper surface of the retaining plate 75 that is inside the guide ring 76 is a planar retaining surface 75a for holding the semiconductor wafer W. A support ring 77 is erected on the retaining surface 75a of the retaining plate 75. The support ring 77 is an annular convex portion. The support ring 77 is provided on the upper surface of the retaining plate 75 such that its annular shape is concentric with the outer circumference of the retaining surface 75a (the inner circumference of the guide ring 76). The diameter of the annular support ring 77 is smaller than the diameter of the semiconductor wafer W (φ300 mm in the first embodiment), and in the first embodiment it is φ180 mm. The support ring 77 is made of quartz. The support ring 77 may be provided on the upper surface of the retaining plate 75 by welding, or it may be manufactured integrally with the retaining plate 75.

[0044] 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.

[0045] 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 held on the susceptor 74 with its lower surface supported by the support ring 77. When the semiconductor wafer W is placed on the support ring 77, a sealed space is formed, enclosed by the upper surface of the holding plate 75, the lower surface of the semiconductor wafer W, and the inner wall surface of the support ring 77.

[0046] Furthermore, the semiconductor wafer W is supported by the support ring 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 support ring 77. Therefore, horizontal displacement of the semiconductor wafer W supported by the support ring 77 is prevented by the guide ring 76.

[0047] 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 portion 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. Note that there is no opening on the inner side of the support ring 77 on the holding surface 75a of the holding plate 75.

[0048] Figure 5 is a plan view of the transfer mechanism 10. Figure 6 is a side 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 pair of transfer arms 11 horizontally between a transfer operation position (solid line position in Figure 5) where the semiconductor wafer W is transferred to the holding part 7 and a retracted position (dotted line position in Figure 5) where the semiconductor wafer W held by the holding part 7 does not overlap 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.

[0049] Furthermore, the pair of transfer arms 11 are moved up and down 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, a total of four lift pins 12 pass through through holes 79 (see Figures 2 and 3) drilled 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 and removes the lift pins 12 from the through holes 79, and the horizontal movement mechanism 13 moves the pair of transfer arms 11 to open, each transfer arm 11 moves to a retracted position. The retracted position of the pair of transfer arms 11 is directly above the base ring 71 of the holding part 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. 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.

[0050] Returning to Figure 1, the flash heating unit 5, located above the chamber 6, is configured with 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 top of the light source. A lamp light emission window 53 is also attached to 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. As 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.

[0051] 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. The area in which the multiple flash lamps FL are arranged is larger than the planar size of the semiconductor wafer W.

[0052] A xenon flash lamp FL comprises a cylindrical glass tube (discharge tube) containing xenon gas, with an anode and cathode connected to capacitors 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 xenon 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 one second. Furthermore, the illumination 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.

[0053] 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.

[0054] 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.

[0055] Figure 7 is a plan view showing the arrangement of multiple halogen lamps HL. The 40 halogen lamps HL are arranged in two rows, upper and lower. Twenty halogen lamps HL are arranged in the upper row, which is closer to the holding part 7, and another 20 halogen lamps HL are arranged in the lower row, which is further from the holding part 7. Each halogen lamp HL is a rod-shaped lamp with a long cylindrical shape. In both the upper and lower rows, 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 part 7 (i.e., along the horizontal direction). Therefore, the planes formed by the arrangement of halogen lamps HL in both the upper and lower rows are horizontal planes.

[0056] Furthermore, as shown in Figure 7, in both the upper and lower sections, the arrangement density of halogen lamps HL is higher 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 lamps HL is shorter at the periphery than at the center of the lamp arrangement. Therefore, 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.

[0057] 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.

[0058] 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.

[0059] Furthermore, a reflector 43 is also provided inside the housing 41 of the halogen heating unit 4, below the two-tiered halogen lamps HL (Figure 1). The reflector 43 reflects the light emitted from the multiple halogen lamps HL towards the heat treatment space 65.

[0060] As shown in Figure 1, the heat treatment apparatus 1 includes an upper radiation thermometer 25 and a lower radiation thermometer 20. The upper radiation thermometer 25 is installed 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 installed 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.

[0061] 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 storage unit (for example, a magnetic disk or SSD) 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.

[0062] 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.

[0063] Next, the processing operation of the heat treatment apparatus 1 having the above configuration will be described. Figure 8 is a flowchart showing the processing procedure of the first embodiment of the heat treatment apparatus 1. The processing procedure of the heat treatment apparatus 1 described below proceeds as the control unit 3 controls each operating mechanism of the heat treatment apparatus 1.

[0064] First, prior to processing the semiconductor wafer W, valve 84 for supplying air is opened, and exhaust valves 89 and 192 are opened to begin supplying and exhausting 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 inside the chamber 6 is exhausted from the gas exhaust hole 86. Furthermore, when valve 192 is opened, the gas inside the chamber 6 is also exhausted from the transport opening 66. As a result, the nitrogen gas supplied from the top of the heat treatment space 65 inside the chamber 6 flows downward and is exhausted from the bottom of the heat treatment space 65.

[0065] Next, the gate valve 185 opens, the transport opening 66 is opened, and the disc-shaped 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 (step S11). 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.

[0066] The semiconductor wafer W, loaded by the transport robot, moves forward to a position directly above the holding section 7 and stops. Then, the pair of transfer arms 11 of the transfer mechanism 10 move horizontally from the retracted position to the transfer operation position and rise, causing the lift pin 12 to protrude from the upper surface of the holding plate 75 of the susceptor 74 through the through hole 79 and receive the semiconductor wafer W. At this time, the lift pin 12 rises above the upper end of the support ring 77.

[0067] 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 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 unit 7 and held from below in a horizontal position. The semiconductor wafer W is placed on the support ring 77 erected on the holding plate 75 and held by the susceptor 74 (step S12). The semiconductor wafer W is also held in the holding unit 7 with the surface to be processed facing upwards. There are no openings in the area of ​​the holding plate 75 inside the support ring 77. Therefore, when the semiconductor wafer W is placed on the support ring 77, a sealed space is formed surrounded by the upper surface of the holding plate 75, the back surface of the semiconductor wafer W (the main surface opposite to the front surface), and the inner wall surface of the support ring 77. The pair of transfer arms 11, which have descended to below the susceptor 74, are moved to a retracted position, i.e., inside the recess 62, by the horizontal movement mechanism 13.

[0068] 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) (step S13). The halogen light emitted from the halogen lamps HL passes through the lower chamber window 64 and the susceptor 74 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 and does not interfere with heating by the halogen lamps HL.

[0069] When preheating is performed using a halogen lamp HL, the temperature of the semiconductor wafer W is measured by a lower radiation thermometer 20. Specifically, the lower radiation thermometer 20 receives infrared light emitted from the lower surface of the semiconductor wafer W held by the susceptor 74 through an opening 78 via a transparent window 21 to measure the wafer temperature during heating. 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. In other words, 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. Thus, the lower radiation thermometer 20 is a radiation thermometer for temperature control of the semiconductor wafer W during preheating.

[0070] 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.

[0071] 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.

[0072] 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 (step S14). 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.

[0073] The flash light emitted from the flash lamp FL is an extremely short and intense flash of light with an irradiation time of approximately 0.1 milliseconds to 100 milliseconds, obtained by converting electrostatic energy previously stored in a capacitor into an extremely short light pulse. When such an extremely short and intense flash of light is emitted, the surface temperature of the semiconductor wafer W instantaneously rises to a processing temperature T2 of over 1000°C, and then rapidly decreases.

[0074] Figure 9 schematically illustrates the phenomenon that occurs when flash light is irradiated. When flash light is irradiated from the flash lamp FL, the surface temperature of the semiconductor wafer W instantaneously rises to a relatively high temperature of over 1000°C, causing the pressure in the space 95 near the surface to increase. On the other hand, the temperature of the back surface of the semiconductor wafer W does not rise significantly, and the pressure in the sealed space 96 surrounded by the upper surface of the holding plate 75, the back surface of the semiconductor wafer W, and the inner wall surface of the support ring 77 is kept relatively low. As a result, as shown in Figure 9, the pressure difference between the space 95 above the wafer and the sealed space 96 causes a downward pressing force to act on the surface of the semiconductor wafer W, suppressing deformation of the semiconductor wafer W into a convex shape and preventing the semiconductor wafer W from jumping off the susceptor 74. This reduces damage to the back surface of the wafer caused by the jumping of the semiconductor wafer W and also prevents cracking of the semiconductor wafer W.

[0075] After the flash heating process is completed, the halogen lamp HL is turned off after a predetermined time has elapsed. 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 a predetermined temperature based on the measurement result of the lower radiation thermometer 20. After the temperature of the semiconductor wafer W has cooled down to below the predetermined temperature, the pair of transfer arms 11 of the transfer mechanism 10 move horizontally again from the retracted position to the transfer operation position and rise, causing the lift pin 12 to protrude from the upper surface of the susceptor 74 and receive the heat-treated semiconductor wafer W from the susceptor 74. 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 transported out of the chamber 6 by a transport robot outside the apparatus, completing the heat treatment of the semiconductor wafer W (step S15).

[0076] In the first embodiment, a support ring 77, which is a convex portion of an annular-shaped quartz having a diameter smaller than the diameter of the semiconductor wafer W, is erected on the upper surface of the holding plate 75 of the susceptor 74. When processing the semiconductor wafer W, the semiconductor wafer W is placed on the support ring 77 and held by the susceptor 74. When the semiconductor wafer W is placed on the support ring 77, a sealed space 96 is formed surrounded by the upper surface of the holding plate 75, the lower surface of the semiconductor wafer W, and the inner wall surface of the support ring 77. When flash light is irradiated, the pressure difference that arises between the space 95 above the semiconductor wafer W and the sealed space 96 causes a downward force to act on the surface of the semiconductor wafer W, suppressing the jumping of the semiconductor wafer W. In other words, by providing an annular-shaped support ring 77 on the susceptor 74, it is possible to prevent the semiconductor wafer W from jumping during flash light irradiation, prevent wafer cracking, and improve yield.

[0077] Furthermore, in the first embodiment, the semiconductor wafer W is supported by a support ring 77 having a diameter smaller than the diameter of the semiconductor wafer W. Since the support ring 77 supports the area inside the outer edge of the semiconductor wafer W, the outer edge becomes an open end. Therefore, even when flash light is irradiated, the outer edge of the semiconductor wafer W can move slightly, and strong restraining stress does not act on the semiconductor wafer W. This makes it possible to more effectively prevent cracking of the semiconductor wafer W.

[0078] <Second Embodiment> Next, a second embodiment of the present invention will be described. The configuration of the heat treatment apparatus in the second embodiment is the same as that of the heat treatment apparatus 1 in the first embodiment. In the second embodiment, the sealed space 96 is a reduced-pressure atmosphere.

[0079] Figure 10 is a flowchart showing the processing procedure of the second embodiment. First, as in the first embodiment, the supply and exhaust of nitrogen gas to the chamber 6 is started, and the semiconductor wafer W is loaded into the chamber 6 (step S21). The semiconductor wafer W loaded by the transport robot moves forward to a position directly above the holding section 7 and stops. Then, the pair of transfer arms 11 of the transfer mechanism 10 move horizontally from the retracted position to the transfer operation position and rise, causing the lift pin 12 to protrude from the upper surface of the holding plate 75 of the susceptor 74 through the through hole 79 and receive the semiconductor wafer W. In the second embodiment, the lift pin 12 waits for a while with the lift pin 12 raised above the support ring 77, maintaining the state in which the lift pin 12 supports the semiconductor wafer W (step S22).

[0080] Figure 11 schematically shows the state in which the lift pin 12 supports the semiconductor wafer W. As the lift pin 12 rises, the upper end of the lift pin 12 protrudes from the holding plate 75 and is positioned above the support ring 77. Therefore, the semiconductor wafer W supported by the lift pin 12 and the support ring 77 are not in contact, and the area below the semiconductor wafer W is an open space. In other words, the sealed space 96 described above is not formed at this point.

[0081] Next, with the semiconductor wafer W supported by the lift pins 12, the pressure inside the chamber 6 is reduced (step S23). Specifically, the valve 84 for supplying air is closed, and while operating the exhaust unit 190 including the vacuum pump, the exhaust valves 89 and 192 are opened to evacuate the atmosphere inside the chamber 6, reducing the pressure inside the chamber 6 to below atmospheric pressure. At this time, the pressure inside the chamber 6 is reduced to a first atmospheric pressure (for example, 100 Pa).

[0082] Figure 12 schematically shows the state in which the pressure inside the chamber 6 is reduced to below atmospheric pressure while the lift pin 12 is supporting the semiconductor wafer W. Since the inside of the support ring 77 is not a sealed space but is open, when the pressure inside the chamber 6 is reduced to a first atmospheric pressure, the space below the semiconductor wafer W, including the inside of the support ring 77, also becomes the first atmospheric pressure.

[0083] After the chamber 6, including the space inside the support ring 77, is depressurized to a first atmospheric pressure, the lift pin 12 descends and the semiconductor wafer W is placed on the support ring 77 (step S24). More specifically, as the pair of transfer arms 11 descend, the lift pin 12 also descends below the holding plate 75, and the semiconductor wafer W, which was supported by the lift pin 12, is passed and placed on the support ring 77.

[0084] Figure 13 schematically shows the state in which a semiconductor wafer W is placed on the support ring 77. When the semiconductor wafer W is placed on the support ring 77, a sealed space 96 is formed surrounded by the upper surface of the holding plate 75, the back surface of the semiconductor wafer W, and the inner wall surface of the support ring 77. In the second embodiment, since the semiconductor wafer W is placed on the support ring 77 with the pressure inside the chamber 6 reduced to a first atmospheric pressure, the sealed space 96 also becomes a first atmospheric pressure, which is below atmospheric pressure. At this point, the space above the semiconductor wafer W is also at the first atmospheric pressure.

[0085] Subsequently, with the semiconductor wafer W placed on the support ring 77, the chamber 6 is repressurized (step S25). Specifically, the air supply valve 84 is briefly opened to supply a small amount of nitrogen gas into the chamber 6, raising the pressure inside the chamber 6 from the first atmospheric pressure to the second atmospheric pressure. At this time, the exhaust valves 89,192 may be left open or temporarily closed. The second atmospheric pressure is higher than the first atmospheric pressure, for example, 5000 Pa. Alternatively, a large amount of nitrogen gas may be supplied into the chamber 6 to restore the pressure inside the chamber 6 to atmospheric pressure (0.1 MPa).

[0086] Figure 14 schematically shows the state in which the chamber 6 has been repressurized. Even if the chamber 6 is repressurized to the second atmospheric pressure, the atmosphere inside the chamber 6 does not flow into the sealed space 96, so the sealed space 96 is maintained at the first atmospheric pressure. On the other hand, the space inside the chamber 6, excluding the sealed space 96, is repressurized to the second atmospheric pressure. Therefore, a pressure difference is created between the space above the semiconductor wafer W supported by the support ring 77 and the sealed space 96.

[0087] The processing content of steps S26 to S28 is the same as steps S13 to S15 in Figure 8. That is, after the semiconductor wafer W is supported by the support ring 77 and the chamber 6 is restored to pressure, preheating of the semiconductor wafer W is performed by light irradiation from 40 halogen lamps HL of the halogen heating unit 4 (step S26). When preheating is performed with halogen lamps HL, the temperature of the semiconductor wafer W is measured by the lower radiation thermometer 20. Based on the measurement value from the lower radiation thermometer 20, the control unit 3 feedback-controls the output of the halogen lamps HL so that the temperature of the semiconductor wafer W becomes the preheating temperature T1.

[0088] 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 in the susceptor 74 with flash light (step S27). Due to the irradiation of a very short duration and high intensity flash light, the surface temperature of the semiconductor wafer W instantaneously rises to a processing temperature T2 of 1000°C or higher, and then rapidly decreases.

[0089] In the second embodiment, a pressure difference is generated between the space above the semiconductor wafer W and the sealed space 96 even before flash light irradiation, and a downward force acts on the surface of the semiconductor wafer W when the surface temperature of the semiconductor wafer W rises rapidly during flash light irradiation. Therefore, deformation of the semiconductor wafer W into a convex shape during flash light irradiation is suppressed, and the semiconductor wafer W is prevented from jumping off the susceptor 74. As a result, scratches on the back surface of the wafer caused by the jumping of the semiconductor wafer W can be reduced, and cracking of the semiconductor wafer W can also be prevented.

[0090] After the flash heating process is completed, the halogen lamp HL is turned off after a predetermined time has elapsed, and the temperature of the semiconductor wafer W drops below the preheating temperature T1. Then, after the temperature of the semiconductor wafer W has dropped below a predetermined level, the semiconductor wafer W is removed from the chamber 6 by a transport robot outside the apparatus (step S28).

[0091] In the second embodiment, the pressure inside the chamber 6 is reduced to a first atmospheric pressure before the semiconductor wafer W is placed on the support ring 77, and then the pressure inside the chamber 6 is restored to a second atmospheric pressure after the semiconductor wafer W is placed on the support ring 77. As a result, when the flash light is irradiated, the sealed space 96 surrounded by the upper surface of the holding plate 75, the lower surface of the semiconductor wafer W, and the inner wall surface of the support ring 77 is at the first atmospheric pressure, while the space inside the chamber 6 excluding the sealed space 96 is at the second atmospheric pressure, creating a pressure difference between the space above the semiconductor wafer W and the sealed space 96. Therefore, when the flash light is irradiated, a downward force acts on the surface of the semiconductor wafer W due to this pressure difference, preventing the semiconductor wafer W from jumping and preventing wafer cracking, similar to the first embodiment.

[0092] Furthermore, in the second embodiment, since the sealed space 96 is intentionally kept under reduced pressure, a pressure difference can be reliably created between the space above the semiconductor wafer W and the sealed space 96, thereby more effectively applying a downward force to the semiconductor wafer W and preventing it from jumping.

[0093] <Third Embodiment> Next, a third embodiment of the present invention will be described. In the third embodiment, the sealed space 96 is subjected to a reduced pressure atmosphere, similar to the second embodiment, but a dedicated pressure reduction mechanism is provided for this purpose.

[0094] Figure 15 shows an example of a depressurization mechanism for reducing the pressure in a sealed space 96. In Figure 15, elements identical to those in the first embodiment are denoted by the same reference numerals. As in the first embodiment, when a semiconductor wafer W is placed on the support ring 77, a sealed space 96 is formed, surrounded by the upper surface of the holding plate 75, the lower surface of the semiconductor wafer W, and the inner wall surface of the support ring 77. In the third embodiment, an exhaust port 121 is provided near the center of the holding plate 75 of the susceptor 74. The exhaust port 121 is provided so as to penetrate the holding plate 75 vertically, and the tip opening of the exhaust port 121 communicates with the sealed space 96. The exhaust port 121 may be formed integrally with the holding plate 75, or it may be a component independent of the holding plate 75.

[0095] The exhaust port 121 is connected to the exhaust pipe 122. One end of the exhaust pipe 122 is connected to the exhaust port 121, and the other end is connected to the ejector 130. A valve 123 and a pressure sensor 124 are provided along the path of the exhaust pipe 122.

[0096] The ejector 130 is a device that creates a reduced pressure state by utilizing the Venturi effect of a fluid. When valve 132 is opened, high-pressure nitrogen gas is sent from the nitrogen supply source 131 to the ejector 130. The pressure of the supplied nitrogen gas is defined by the regulator 133. When high-pressure nitrogen gas flows through the tube of the ejector 130, negative pressure is generated in the surrounding area. If valve 123 is open, this negative pressure is applied to the exhaust port 121 via the exhaust pipe 122. In other words, by flowing high-pressure nitrogen gas through the ejector 130, negative pressure acts on the exhaust port 121, and as a result, the sealed space 96 is depressurized. The nitrogen gas that has passed through the ejector 130 is exhausted from the exhaust port 121 along with the gas that has been drawn in. Note that the fluid supplied to the ejector 130 is not limited to nitrogen gas; for example, it may be air. The configuration of the remaining heat treatment device is the same as in the first embodiment, except that a depressurization mechanism is provided to depressurize the sealed space 96.

[0097] Figure 16 is a flowchart showing the processing procedure of the third embodiment. First, as in the first embodiment, the supply and exhaust of nitrogen gas to the chamber 6 is started, and the semiconductor wafer W is brought into the chamber 6 by a transport robot (step S31). Then, as in the first embodiment, the lift pin 12 rises to receive the semiconductor wafer W from the transport robot, and after the transport robot exits, the lift pin 12 lowers and the semiconductor wafer W is placed on the support ring 77 (step S32). When the semiconductor wafer W is placed on the support ring 77, a sealed space 96 is formed surrounded by the upper surface of the holding plate 75, the back surface of the semiconductor wafer W, and the inner wall surface of the support ring 77.

[0098] In the third embodiment, the sealed space 96 is depressurized by the depressurization mechanism including the ejector 130 (step S33). Specifically, valve 132 is opened to supply high-pressure nitrogen gas to the ejector 130, and valve 123 is also opened. The negative pressure generated by the passage of high-pressure nitrogen gas through the ejector 130 acts on the exhaust port 121, depressurizing the sealed space 96. As a result, similar to Figure 14 of the second embodiment, the pressure in the space above the semiconductor wafer W supported by the support ring 77 becomes relatively higher than that in the depressurized sealed space 96, creating a pressure difference between the space above the semiconductor wafer W and the sealed space 96.

[0099] The processing in the subsequent steps S34 to S36 is the same as steps S13 to S15 in Figure 8. That is, after the semiconductor wafer W is supported by the support ring 77 and the sealed space 96 is depressurized, preheating of the semiconductor wafer W is performed by light irradiation from the 40 halogen lamps HL of the halogen heating unit 4 (step S34). When preheating is performed with the halogen lamps HL, the temperature of the semiconductor wafer W is measured by the lower radiation thermometer 20. Based on the measurement value from the lower radiation thermometer 20, the control unit 3 feedback-controls the output of the halogen lamps HL so that the temperature of the semiconductor wafer W becomes the preheating temperature T1.

[0100] When the temperature of 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 in the susceptor 74 with flash light (step S35). Due to the irradiation of a very short duration and high intensity flash light, the surface temperature of the semiconductor wafer W instantaneously rises to a processing temperature T2 of 1000°C or higher, and then rapidly decreases.

[0101] In the third embodiment, similar to the second embodiment, a pressure difference is generated between the space above the semiconductor wafer W and the sealed space 96 before flash light irradiation, and even when the surface temperature of the semiconductor wafer W rises rapidly during flash light irradiation, a downward force acts on the surface of the semiconductor wafer W from above. Therefore, deformation of the semiconductor wafer W into a convex shape during flash light irradiation is suppressed, and the semiconductor wafer W is prevented from jumping off the susceptor 74. As a result, scratches on the back surface of the wafer caused by the jumping of the semiconductor wafer W can be reduced, and cracking of the semiconductor wafer W can also be prevented.

[0102] After the flash heating process is completed, the halogen lamp HL is turned off after a predetermined time has elapsed, and the temperature of the semiconductor wafer W drops below the preheating temperature T1. Then, after the temperature of the semiconductor wafer W has dropped below a predetermined level, the semiconductor wafer W is removed from the chamber 6 by a transport robot outside the apparatus (step S36).

[0103] In the third embodiment, after the semiconductor wafer W is placed on the support ring 77, the pressure is reduced in the sealed space 96 surrounded by the upper surface of the holding plate 75, the lower surface of the semiconductor wafer W, and the inner wall surface of the support ring 77. As a result, a pressure difference is created between the space above the semiconductor wafer W and the sealed space 96, similar to the second embodiment. Therefore, when flash light is irradiated, this pressure difference acts as a downward pressing force on the surface of the semiconductor wafer W, preventing the semiconductor wafer W from jumping and preventing wafer cracking, similar to the first embodiment.

[0104] Furthermore, in the third embodiment, since the sealed space 96 is intentionally depressurized, a pressure difference can be reliably created between the space above the semiconductor wafer W and the sealed space 96, thereby more effectively applying a downward force to the semiconductor wafer W and preventing the semiconductor wafer from jumping.

[0105] <Variation> While embodiments of the present invention have been described above, various modifications can be made to this invention without departing from its spirit. For example, in the first embodiment, a φ180 mm annular support ring 77 was provided on the holding plate 75 of the susceptor 74, but the invention is not limited to this, and various forms of the support ring 77 can be adopted as shown below. Figures 17 to 20 are plan views showing other examples of the support ring 77.

[0106] In the example shown in Figure 17, a smaller diameter, φ100 mm, annular support ring 77 is provided on the holding plate 75 of the susceptor 74. Even with such a small-diameter support ring 77, the same effects as in the above embodiments can be obtained by placing the semiconductor wafer W on it. Note that the diameter of the support ring 77 is not limited to φ180 mm or φ100 mm; it can be any appropriate value that is smaller than the diameter of the semiconductor wafer W and is capable of supporting the semiconductor wafer W.

[0107] In the example shown in Figure 18, the support ring 77 is a double ring. That is, the support ring 77 is composed of an inner ring 77a and an outer ring 77b. Each of the inner ring 77a and the outer ring 77b is a convex portion of an annular quartz. The diameter of the outer ring 77b is, for example, φ180 mm, and the diameter of the inner ring 77a is, for example, φ90 mm. Both the inner ring 77a and the outer ring 77b are arranged concentrically with the inner circumference of the guide ring 76. In the example shown in Figure 18, when a semiconductor wafer W is placed on the inner ring 77a and the outer ring 77b, an inner sealed space is formed, surrounded by the upper surface of the holding plate 75, the lower surface of the semiconductor wafer W, and the inner wall surface of the inner ring 77a, as well as an outer sealed space, surrounded by the upper surface of the holding plate 75, the lower surface of the semiconductor wafer W, the outer wall surface of the inner ring 77a, and the inner wall surface of the outer ring 77b.

[0108] In the example shown in Figure 18, two sealed spaces are formed by placing the semiconductor wafer W on the support ring 77, and the same effects as in each of the above embodiments can be obtained. When the example shown in Figure 18 is applied to the third embodiment, the inner and outer sealed spaces may be depressurized separately and independently so that they have different pressures. For example, the pressure in the outer sealed space may be relatively higher than the pressure in the inner sealed space (however, the pressure in the outer sealed space is also lower than the pressure in the space above the semiconductor wafer W). Furthermore, the support ring 77 may be a multi-ring structure of three or more rings, and it is acceptable as long as a plurality of annular support rings of different diameters are arranged concentrically.

[0109] Furthermore, in the examples shown in Figures 19 and 20, multiple small-sized support rings 77 are provided on the holding plate 75 of the susceptor 74. In the example shown in Figure 19, four support rings 77 are arranged at 90° intervals, and in the example shown in Figure 20, eight support rings 77 are arranged at 45° intervals. Each of the multiple support rings 77 shown in Figures 19 and 20 is a convex portion of an annular-shaped quartz, with a diameter of, for example, φ10 mm. In the examples shown in Figures 19 and 20, the semiconductor wafer W is supported by the multiple support rings 77. When the semiconductor wafer W is placed on the multiple support rings 77, multiple sealed spaces are formed, surrounded by the upper surface of the holding plate 75, the lower surface of the semiconductor wafer W, and the inner wall surfaces of each support ring 77. The same effects as in the above embodiments can be obtained in this way as well. Note that the number of support rings 77 provided on the susceptor 74 is not limited to four or eight, but can be any number as appropriate.

[0110] Furthermore, in each of the above embodiments, the support ring 77 was a circular annular shape, but the shape of the support ring 77 may be, for example, elliptical. The shape of the support ring 77 should be annular, such that a sealed space can be formed by the upper surface of the holding plate 75, the lower surface of the semiconductor wafer W, and the inner wall surface of the support ring 77.

[0111] Furthermore, in the third embodiment, the sealed space 96 was depressurized by the ejector 130, but instead, the sealed space 96 may be depressurized by, for example, a vacuum pump.

[0112] Furthermore, while the flash heating unit 5 is equipped with 30 flash lamps FL in each of the above embodiments, the number of flash lamps FL is not limited to this, and 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.

[0113] Furthermore, in each of the above embodiments, a filament-type halogen lamp HL was used as a continuous-lighting lamp that emitted light continuously for 1 second or more to perform the preheating treatment of 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 the preheating treatment. [Explanation of Symbols]

[0114] 1 Heat treatment apparatus 3. Control Unit 4. Halogen heating section 5. Flash heating section 6 chambers 7 Holding part 10 Transfer mechanism 20 Lower radiation thermometer 25 Upper radiation thermometer 63 Upper chamber window 64 Lower chamber window 65 Heat treatment space 74 Susceptors 75 Retaining plate 76 Guide Rings 77 Support ring 77a Inner ring 77b Outer ring 96 Closed space 121 Exhaust Port 130 Ejectors FL Flash Lamp HL halogen lamp W Semiconductor wafer

Claims

1. A heat treatment apparatus for heating a disc-shaped substrate by irradiating it with flash light, A chamber for housing the circuit board, A susceptor that holds the substrate within the chamber, A flash lamp that irradiates the substrate held by the susceptor with flash light, Equipped with, The susceptor is, A flat quartz retaining plate, An annular convex portion of quartz having a diameter smaller than the diameter of the substrate is erected on the upper surface of the retaining plate, A heat treatment apparatus including a heat treatment device.

2. In the heat treatment apparatus according to claim 1, A heat treatment apparatus in which, when the substrate is placed on the convex portion, a sealed space is formed surrounded by the upper surface of the holding plate, the lower surface of the substrate, and the convex portion.

3. In the heat treatment apparatus according to claim 2, A heat treatment apparatus further comprising a depressurization mechanism for reducing the pressure in the aforementioned sealed space.

4. In the heat treatment apparatus according to claim 3, The aforementioned pressure reduction mechanism is An exhaust port provided on the retaining plate, An ejector that applies negative pressure to the exhaust port, A heat treatment apparatus including a heat treatment device.

5. In the heat treatment apparatus according to claim 1, A heat treatment apparatus having multiple annular convex portions arranged on the upper surface of the retaining plate.

6. In the heat treatment apparatus according to claim 5, A heat treatment apparatus in which multiple annular convex portions of different diameters are arranged concentrically on the upper surface of the retaining plate.

7. In the heat treatment apparatus according to any one of claims 1 to 6, A heat treatment apparatus further comprising a continuous-lighting lamp that preheats the substrate held in the susceptor by irradiating it with light before irradiating it with the aforementioned flash light.

8. A heat treatment method for heating a disc-shaped substrate by irradiating it with a flash of light, A holding process in which the substrate is held in the susceptor within the chamber, A flash light irradiation step is performed by irradiating the substrate held by the susceptor with flash light from a flash lamp, Equipped with, The susceptor is, A flat quartz retaining plate, An annular convex portion of quartz having a diameter smaller than the diameter of the substrate is erected on the upper surface of the retaining plate, Includes, The heat treatment method involves placing the substrate on the convex portion during the holding step.

9. In the heat treatment method according to claim 8, A heat treatment method in which, when the substrate is placed on the convex portion during the holding step, a sealed space is formed surrounded by the upper surface of the holding plate, the lower surface of the substrate, and the convex portion.

10. In the heat treatment method according to claim 9, A heat treatment method further comprising a depressurization step of reducing the pressure in the sealed space.

11. In the heat treatment method according to claim 10, The aforementioned depressurization process is, Before the substrate is placed on the convex portion, the process involves reducing the pressure inside the chamber, After the substrate is placed on the convex portion, the process involves restoring pressure inside the chamber, A heat treatment method including

12. In the heat treatment method according to any one of claims 8 to 11, A heat treatment method further comprising a preheating step, in which light from a continuously lit lamp is irradiated onto the substrate held in the susceptor to preheat the substrate before the flash light irradiation step.

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