Heat treatment method and heat treatment device

Abstract

The invention provides a heat treatment method and a heat treatment apparatus which can prevent cracks caused by repeated stress from occurring in a substrate when a flash light is irradiated. The current flowing to the flash light emitting the flash light is controlled by the IGBT. The IGBT is repeatedly turned on and off in accordance with the waveform of the pulse signal output from the pulse generator. Since the IGBT is repeatedly turned on and off, the current flowing to the flash lamp is repeatedly increased and decreased, and the surface temperature of the semiconductor wafer is increased while being repeatedly increased and decreased slightly. If the ON / OFF period in the pulse signal is shortened and the ON / OFF period when the IGBT is repeatedly ON / OFF is set to 200 microseconds or less, the variation amplitude of the increase / decrease in the surface temperature of the semiconductor wafer is also reduced. As a result, the value of stress repeatedly acting on the semiconductor wafer becomes less than or equal to the fatigue limit, and wafer cracks caused by repeated stress can be prevented.

Description

Technical Field

[0001] The present invention relates to a heat treatment method and a heat treatment apparatus for heating a substrate by irradiating the substrate with light. The substrate to be treated includes, for example, a semiconductor wafer, a liquid crystal display device substrate, a flat panel display (FPD) substrate, an optical disk substrate, a magnetic disk substrate, or a solar cell substrate. Background Art

[0002] Flash lamp annealing (FLA), which heats semiconductor wafers in an extremely short time, has attracted much attention in the semiconductor device manufacturing process. Flash lamp annealing is a heat treatment technology that uses a xenon flash lamp (hereinafter referred to as a "flash lamp") to irradiate the surface of a semiconductor wafer with flash light, raising the temperature of the semiconductor wafer surface in an extremely short period of time (less than a few milliseconds).

[0003] The radiation spectrum of a xenon flash lamp ranges from the ultraviolet to the near-infrared region, with shorter wavelengths than conventional halogen lamps, nearly aligning with the fundamental absorption band of silicon semiconductor wafers. Therefore, when a xenon flash lamp illuminates a semiconductor wafer, little light is transmitted, allowing the wafer to heat up rapidly. Furthermore, it has been demonstrated that even extremely short flash light exposures of just a few milliseconds can selectively increase the temperature near the surface of the semiconductor wafer.

[0004] Flash lamp annealing is used for processes requiring extremely short heating times, typically for activating impurities implanted into semiconductor wafers. By irradiating the surface of a semiconductor wafer implanted with impurities with flash light from a flash lamp using ion implantation, the surface temperature of the semiconductor wafer can be raised to the activation temperature in a very short time, enabling only impurity activation without deep diffusion of the impurities.

[0005] Regarding heat treatment devices using such xenon flash lamps, Patent Documents 1 and 2 disclose devices that control the flash lamp's light emission by placing an insulated gate bipolar transistor (IGBT) in the flash lamp's discharge circuit. In the devices disclosed in Patent Documents 1 and 2, a specific pulse signal is input to the IGBT's gate, causing the IGBT to repeatedly switch on and off at high speed according to the waveform of the pulse signal. This allows the waveform of the current flowing to the flash lamp to be controlled, allowing the lamp's light emission to be freely adjusted, including the duration and intensity of the flash lamp's light emission.

[0006] [Background Art Literature]

[0007] [Patent Document]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-070948

[0009] [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-119562 Summary of the Invention

[0010] [Problems to be solved by the invention]

[0011] During flash lamp annealing, a flash of extremely high energy is applied to a semiconductor wafer in a very short time. This causes instantaneous stress on the semiconductor wafer, which can sometimes cause wafer cracks. In particular, when using an IGBT to control the current flowing to the flash lamp, as disclosed in Patent Documents 1 and 2, the IGBT repeatedly switches on and off in a short period of time, causing the current flowing through the circuit including the flash lamp to repeatedly increase and decrease on a microscopic level. As a result, the surface temperature of the semiconductor wafer also repeatedly increases and decreases slightly while reaching the target temperature. This repeated increase and decrease in the surface temperature of the semiconductor wafer in a short period of time exerts repeated stress on the semiconductor wafer. Consequently, the semiconductor wafer becomes more susceptible to cracking due to a mechanism similar to fatigue failure.

[0012] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a heat treatment method and a heat treatment apparatus that can prevent cracks from being generated in a substrate due to repeated stress when irradiated with flash light.

[0013] [Technical means to solve the problem]

[0014] In order to solve the above-mentioned problem, the first form of the present invention is a heat treatment method for heating a substrate by irradiating light onto the substrate, comprising: a preheating step of irradiating light from a continuously lit lamp onto the substrate to heat the substrate to a specific preheating temperature; and a flash heating step of irradiating flash light from a plurality of flash lamps onto the surface of the substrate after the preheating step, thereby heating the surface of the substrate to a specific treatment temperature; and in the flash heating step, controlling the current flowing to the plurality of flash lamps by a switching element, and in the flash heating step, setting the on and off cycle of the switching element to less than 200 microseconds.

[0015] Furthermore, a second aspect is the heat treatment method according to the first aspect, wherein in the flash heating step, a voltage of 3400 V or less is applied to the plurality of flash lamps.

[0016] Furthermore, a third aspect is the heat treatment method according to the second aspect, wherein in the flash heating step, a difference between a maximum value and a minimum value of the surface temperature of the substrate caused by turning on and off the switching element is set to 10° C. or less.

[0017] In addition, a fourth aspect is a heat treatment method according to any one of the first to third aspects, wherein the plurality of flash lamps include a first flash lamp and a second flash lamp, and in the flash heating step, the current flowing to the first flash lamp is controlled by a first switching element, and the current flowing to the second flash lamp is controlled by a second switching element, and in the flash heating step, the second switching element is turned off when the first switching element is turned on, and the second switching element is turned on when the first switching element is turned off.

[0018] In addition, the fifth form is a heat treatment method for heating a substrate by irradiating light onto the substrate, comprising: a preheating step of irradiating light from a continuously lit lamp onto the substrate to heat the substrate to a specific preheating temperature; and a flash heating step of irradiating flash light from a plurality of flash lamps onto the surface of the substrate after the preheating step, thereby heating the surface of the substrate to a specific treatment temperature; and the plurality of flash lamps include a first flash lamp and a second flash lamp, in the flash heating step, the current flowing to the first flash lamp is controlled by a first switching element, and the current flowing to the second flash lamp is controlled by a second switching element, in the flash heating step, the second switching element is disconnected when the first switching element is turned on, and the second switching element is turned on when the first switching element is turned off.

[0019] Furthermore, a sixth aspect is the heat treatment method according to the fifth aspect, wherein different pulse signals for turning on and off are individually given to the first switching element and the second switching element.

[0020] In addition, the seventh aspect is the heat treatment method according to the fifth aspect, wherein a common pulse signal for switching on and off is given to the first switching element and the second switching element, and the pulse signal given to the second switching element is inverted by an inverting circuit.

[0021] In addition, the eighth form is a heat treatment device for heating a substrate by irradiating the substrate with light, comprising: a chamber for storing the substrate; a continuously lit lamp for irradiating the substrate stored in the chamber with light to heat the substrate to a specific preheating temperature; a plurality of flash lamps for irradiating the surface of the substrate heated to the preheating temperature with flash light to raise the temperature of the surface of the substrate to a specific processing temperature; a plurality of switching elements for controlling the current flowing to the plurality of flash lamps; and a pulse generator for generating a pulse signal for turning the plurality of switching elements on and off; and the on and off period of the pulse signal output by the pulse generator to the plurality of switching elements is set to less than 200 microseconds.

[0022] Furthermore, a ninth aspect is the heat treatment apparatus according to the eighth aspect, further comprising a capacitor for supplying power to the plurality of flash lamps, wherein a charging voltage of the capacitor is set to 3400 V or less.

[0023] Furthermore, a tenth aspect is the heat treatment apparatus according to the ninth aspect, wherein a difference between a maximum value and a minimum value of the surface temperature of the substrate caused by turning on and off the plurality of switching elements when irradiating the flashlight from the plurality of flashlamps is set to 10° C. or less.

[0024] In addition, the 11th form is a heat treatment device according to any one of the 8th to 10th forms, wherein the plurality of flash lamps include a first flash lamp and a second flash lamp, and the plurality of switching elements include a first switching element for controlling the current flowing to the first flash lamp and a second switching element for controlling the current flowing to the second flash lamp, and when flash light is irradiated from the flash lamp, the second switching element is turned off when the first switching element is turned on, and the second switching element is turned on when the first switching element is turned off.

[0025] In addition, the 12th form is a heat treatment device for heating a substrate by irradiating light onto the substrate, comprising: a chamber for storing a substrate; a continuously lit lamp for irradiating light onto the substrate stored in the chamber to heat the substrate to a specific preheating temperature; a plurality of flash lamps for heating the surface of the substrate heated to the preheating temperature to a specific processing temperature by irradiating flash light onto the surface of the substrate; a plurality of switching elements for controlling the current flowing to the plurality of flash lamps; and a pulse generator for generating a pulse signal for turning the plurality of switching elements on and off; and the plurality of flash lamps include a first flash lamp and a second flash lamp, the plurality of switching elements include a first switching element for controlling the current flowing to the first flash lamp and a second switching element for controlling the current flowing to the second flash lamp, and when flash light is irradiated from the flash lamp, the second switching element is turned off when the first switching element is turned on, and the second switching element is turned on when the first switching element is turned off.

[0026] Furthermore, a thirteenth aspect is the heat treatment apparatus according to the twelfth aspect, wherein the pulse generator outputs different pulse signals to the first switching element and the second switching element, respectively.

[0027] In addition, the 14th form is a heat treatment device according to the 12th form, wherein the pulse generator outputs a common pulse signal to the first switching element and the second switching element, and the heat treatment device further includes an inversion circuit that inverts the pulse signal given to the second switching element.

[0028] [Effects of the Invention]

[0029] According to the first to fourth forms of heat treatment methods, the on-and-off cycle of the switching element that controls the current flowing to the flash lamp is set to less than 200 microseconds. Therefore, the variation amplitude of the surface temperature of the substrate becomes smaller, which can prevent cracks caused by repeated stress in the substrate when the flash light is irradiated.

[0030] According to the heat treatment method of the 5th to 7th forms, in the flash heating step, the second switch element is turned off when the first switch element is turned on, and the second switch element is turned on when the first switch element is turned off. Therefore, the first flash lamp and the second flash lamp cancel each other out the intensities of the emitted light, which can prevent cracks caused by repeated stress from occurring in the substrate when the flash light is irradiated.

[0031] According to the heat treatment apparatus of the 8th to 11th forms, the on and off period of the pulse signal output by the pulse generator to the plurality of switching elements is set to less than 200 microseconds. Therefore, the variation amplitude of the surface temperature of the substrate becomes smaller, and cracks caused by repeated stress when the flash light is irradiated can be prevented from being generated in the substrate.

[0032] According to the heat treatment device of the 12th to 14th forms, when the flash light is irradiated from the flash lamp, the second switch element is turned off when the first switch element is turned on, and the second switch element is turned on when the first switch element is turned off. Therefore, the first flash lamp and the second flash lamp cancel each other out the intensities of the emitted light, which can prevent cracks caused by repeated stress from occurring in the substrate when the flash light is irradiated. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a longitudinal sectional view showing the structure of the heat treatment apparatus of the present invention.

[0034] Figure 2 It is a perspective view showing the overall appearance of the holding portion.

[0035] Figure 3 This is a top view of the base.

[0036] Figure 4 This is a cross-sectional view of the base.

[0037] Figure 5 It is a top view of the transfer mechanism.

[0038] Figure 6 It is a side view of the transfer mechanism.

[0039] Figure 7 It is a plan view showing the arrangement of a plurality of halogen lamps.

[0040] Figure 8 This is a diagram showing a driving circuit for a flash lamp.

[0041] Figure 9This is a graph showing changes in the surface temperature of a semiconductor wafer.

[0042] Figure 10 This is a diagram showing an example of the waveform of a pulse signal input to the IGBT.

[0043] Figure 11 This is a diagram showing changes in the surface temperature of a semiconductor wafer during flash heating.

[0044] Figure 12 This is a graph showing the increase and decrease in the surface temperature of a semiconductor wafer during flash heating.

[0045] Figure 13 This is a diagram showing an example of the waveforms of the pulse signals input to the first IGBT and the second IGBT in the second embodiment.

[0046] Figure 14 This is a diagram showing a driving circuit for the second flash lamp in the third embodiment. DETAILED DESCRIPTION

[0047] Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail. Hereinafter, expressions representing relative or absolute positional relationships (e.g., "in a direction," "along a direction," "parallel," "orthogonal," "center," "concentric," "coaxial," etc.) will not only strictly represent the positional relationship, but also represent the state of relative displacement in the range of tolerance or the same degree of function, as long as no particular advance description is given. In addition, expressions representing equal states (e.g., "same," "equal," "homogeneous," etc.) will not only quantitatively represent the state of strict equality, but also represent the state of difference in the presence of tolerance or the same degree of function, as long as no particular advance description is given. In addition, expressions representing shapes (e.g., "circular," "quadrilateral," "cylindrical," etc.) will not only strictly represent the shape geometrically, but also represent the shape of the range of the same degree of effect, such as concave-convex or chamfered corners, as long as no particular advance description is given. In addition, expressions such as "having," "including," "containing," "containing," and "having" constituent elements are not exclusive expressions that exclude other constituent elements. In addition, the expression "at least one of A, B, and C" includes "only A", "only B", "only C", "any two of A, B, and C", and "all of A, B, and C".

[0048] <First embodiment>

[0049] Figure 1 It is a longitudinal sectional view showing the structure of the heat treatment apparatus 1 of the present invention. Figure 1The heat treatment device 1 is a flash lamp annealing device that heats a semiconductor wafer W in the shape of a circular plate as a substrate by irradiating the semiconductor wafer W with flash light. The size of the semiconductor wafer W to be processed is not particularly limited, and is, for example, φ300 mm or φ450 mm (φ300 mm in this embodiment). Figure 1 In the following drawings, the size and number of each component are exaggerated or simplified as necessary to facilitate understanding.

[0050] The heat treatment apparatus 1 includes: a chamber 6 for accommodating semiconductor wafers W; a flash heating unit 5 containing multiple flash lamps FL; and a halogen heating unit 4 containing multiple halogen lamps HL. The flash heating unit 5 is provided on the upper side of the chamber 6, and the halogen heating unit 4 is provided on the lower side. In addition, the heat treatment apparatus 1 includes: a holding unit 7 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, which controls the halogen heating unit 4, the flash heating unit 5, and the various operating mechanisms provided in the chamber 6 to perform heat treatment on the semiconductor wafer W.

[0051] The chamber 6 is constructed by attaching quartz chamber windows to the top and bottom of a cylindrical chamber side portion 61. The chamber side portion 61 has a generally cylindrical shape with openings at the top and bottom. The upper opening is blocked by an upper chamber window 63, and the lower opening is blocked by a lower chamber window 64. The upper chamber window 63, which constitutes the top wall of the chamber 6, is a disc-shaped member made of quartz and functions as a quartz window that allows the flashlight emitted from the flash heater 5 to pass into the chamber 6. Furthermore, the lower chamber window 64, which constitutes the bottom plate of the chamber 6, is also a disc-shaped member made of quartz and functions as a quartz window that allows the light from the halogen heater 4 to pass into the chamber 6.

[0052] In addition, a reflection ring 68 is installed on the upper portion of the inner wall of the chamber side portion 61, and a reflection ring 69 is installed on the lower portion. Both reflection rings 68 and 69 are formed in a circular ring shape. The upper reflection ring 68 is installed by inserting it from the upper side of the chamber side portion 61. On the other hand, the lower reflection ring 69 is installed by inserting it from the lower side of the chamber side portion 61 and fixing it with screws (not shown). In other words, the reflection rings 68 and 69 are both installed in the chamber side portion 61 in a freely attachable and detachable manner. The inner space of the chamber 6, that is, the space surrounded by the upper chamber window 63, the lower chamber window 64, the chamber side portion 61, and the reflection rings 68 and 69, is defined as the heat treatment space 65.

[0053] By attaching the reflection rings 68 and 69 to the chamber side portion 61, a recess 62 is formed on the inner wall of the chamber 6. Specifically, the recess 62 is surrounded by the central portion of the inner wall of the chamber side portion 61 where the reflection rings 68 and 69 are not attached, the lower end surface of the reflection ring 68, and the upper end surface of the reflection ring 69. The recess 62 is formed in a circular ring shape along the horizontal direction of the inner wall of the chamber 6, surrounding the holding portion 7 that holds the semiconductor wafer W. The chamber side portion 61 and the reflection rings 68 and 69 are formed of a metal material (e.g., stainless steel) with excellent strength and heat resistance.

[0054] Furthermore, a transfer opening (furnace port) 66 for loading and unloading semiconductor wafers W into and out of the chamber 6 is formed in the chamber side portion 61. The transfer opening 66 is configured to be openable and closable by a gate valve 185. The transfer opening 66 is connected to the outer peripheral surface of the recess 62. Therefore, when the gate valve 185 opens the transfer opening 66, the semiconductor wafer W can be loaded into and unloaded from 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 within the chamber 6 becomes a sealed space.

[0055] Furthermore, a through hole 61a and a through hole 61b are formed in the chamber side portion 61. The through hole 61a is a cylindrical hole used to guide infrared light emitted from the upper surface of the semiconductor wafer W held on the susceptor 74 described below to the infrared sensor 29 of the upper radiation thermometer 25. On the other hand, the through hole 61b is a cylindrical hole used to guide infrared light emitted from the lower surface of the semiconductor wafer W to the lower radiation thermometer 20. The through holes 61a and 61b are arranged at an angle relative to the horizontal direction so that the axes of their penetration directions intersect with the main surface of the semiconductor wafer W held on the susceptor 74. A transparent window 26 made of calcium fluoride material is attached to the end of the through hole 61a on the side facing the heat treatment space 65. The window 26 transmits infrared light in the wavelength range that can be measured by the upper radiation thermometer 25. Furthermore, a transparent window 21 made of a barium fluoride material that transmits infrared light in a wavelength range measurable by the lower radiation thermometer 20 is attached to the end portion of the through hole 61 b facing the heat treatment space 65 .

[0056] In addition, a gas supply hole 81 for supplying a processing gas to the heat treatment space 65 is formed on the upper part of the inner wall of the chamber 6. The gas supply hole 81 is formed at a position higher than the recess 62 and can also be provided on the reflection ring 68. The gas supply hole 81 is connected to the gas supply pipe 83 via a buffer space 82 formed in an annular shape inside the side wall of the chamber 6. The gas supply pipe 83 is connected to the processing gas supply source 85. In addition, a valve 84 is inserted in the middle of the path of the gas supply pipe 83. When the valve 84 is opened, the processing gas is transported from the processing gas supply source 85 to the buffer space 82. The processing gas flowing into the buffer space 82 flows in an expanded manner in the buffer space 82 where the fluid resistance is smaller than that of 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), or a reactive gas such as hydrogen (H2) or ammonia (NH3), or a mixed gas thereof (nitrogen in this embodiment) can be used.

[0057] On the other hand, a gas exhaust hole 86 for exhausting the gas in the heat treatment space 65 is formed at the lower part of the inner wall of the chamber 6. The gas exhaust hole 86 is formed at a lower position than the recess 62 and can also be set at the reflection ring 69. The gas exhaust hole 86 is connected to the gas exhaust pipe 88 via a buffer space 87 formed in a circular ring shape inside the side wall of the chamber 6. The gas exhaust pipe 88 is connected to the exhaust part 190. In addition, a valve 89 is inserted in the middle of the path of the gas exhaust pipe 88. When the valve 89 is opened, the gas in the heat treatment space 65 is discharged from the gas exhaust hole 86 through the buffer space 87 to the gas exhaust pipe 88. In addition, the gas supply hole 81 and the gas exhaust hole 86 can be provided in a plurality along the circumferential direction of the chamber 6, or can be in a long strip shape. In addition, the processing gas supply source 85 and the exhaust part 190 can be a mechanism provided in the heat treatment device 1, or can be an entity of the factory where the heat treatment device 1 is provided.

[0058] A gas exhaust pipe 191 for exhausting the gas in the heat treatment space 65 is also connected to the front end of the transfer opening 66. The gas exhaust pipe 191 is connected to the exhaust unit 190 via a valve 192. By opening the valve 192, the gas in the chamber 6 is exhausted through the transfer opening 66.

[0059] Figure 2 : This is a perspective view showing the overall appearance of the holding portion 7. The holding portion 7 is composed of a base ring 71, a connecting portion 72, and a base 74. The base ring 71, the connecting portion 72, and the base 74 are all made of quartz. In other words, the entire holding portion 7 is made of quartz.

[0060] The base ring 71 is a quartz component with a circular arc shape with a portion missing from the circular ring. This missing portion is provided to prevent interference between the transfer arm 11 of the transfer mechanism 10 described below and the base ring 71. The base ring 71 is supported on the wall surface of the chamber 6 by being placed on the bottom surface of the recess 62 (see Figure 1 ). On the upper surface of the base ring 71, a plurality of connecting parts 72 (four in this embodiment) are provided along the circumferential direction of the annular shape. The connecting parts 72 are also made of quartz and are fixed to the base ring 71 by welding.

[0061] The base 74 is supported by four connecting parts 72 provided on the base ring 71 . Figure 3 74 is a top view of the base. Figure 4 This is a cross-sectional view of a 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 plate-shaped member formed of quartz. The diameter of the holding plate 75 is larger than the diameter of the semiconductor wafer W. In other words, the holding plate 75 has a larger planar dimension than the semiconductor wafer W.

[0062] A guide ring 76 is provided on the peripheral edge of the upper surface of the retaining plate 75. The guide ring 76 is a ring-shaped component having an inner diameter larger than the diameter of the semiconductor wafer W. For example, when the diameter of the semiconductor wafer W is φ300 mm, the inner diameter of the guide ring 76 is φ320 mm. The inner periphery of the guide ring 76 is formed into a tapered surface that widens upward from the retaining plate 75. The guide ring 76 is formed of the same quartz as the retaining plate 75. The guide ring 76 can be welded to the upper surface of the retaining plate 75, or it can 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 can be processed into an integral component.

[0063] The area on the upper surface of the retaining plate 75, further inward from the guide ring 76, serves as a planar retaining surface 75a for retaining the semiconductor wafer W. Multiple substrate support pins 77 are provided on the retaining surface 75a of the retaining plate 75. In this embodiment, twelve substrate support pins 77 are provided at 30-degree intervals along a circle concentric with the outer circumference of the retaining surface 75a (the inner circumference of the guide ring 76). The diameter of the circle containing the twelve substrate support pins 77 (the distance between opposing substrate support pins 77) is smaller than the diameter of the semiconductor wafer W. For a semiconductor wafer W with a diameter of 300 mm, the diameter is 270 mm to 280 mm (270 mm in this embodiment). Each substrate support pin 77 is formed from quartz. The multiple substrate support pins 77 can be attached to the upper surface of the retaining plate 75 by welding, or they can be integrally formed with the retaining plate 75.

[0064] Back to Figure 2The four connecting portions 72 erected on the base ring 71 are fixed to the periphery of the retaining plate 75 of the base 74 by welding. In other words, the base 74 and the base ring 71 are fixedly connected via the connecting portions 72. With the base ring 71 of the retaining unit 7 supported on the wall of the chamber 6, the retaining unit 7 is installed in the chamber 6. When the retaining unit 7 is installed in the chamber 6, the retaining plate 75 of the base 74 is in a horizontal position (a position with its normal aligned with the vertical direction). In other words, the retaining surface 75a of the retaining plate 75 is horizontal.

[0065] The semiconductor wafer W loaded into the chamber 6 is placed and held in a horizontal position on a susceptor 74 attached to the holding portion 7 of the chamber 6. At this time, the semiconductor wafer W is supported and held on the susceptor 74 by twelve substrate support pins 77 erected on the holding plate 75. More strictly speaking, the upper ends of the twelve substrate support pins 77 contact the lower surface of the semiconductor wafer W, thereby supporting the semiconductor wafer W. The height 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) is uniform, so the twelve substrate support pins 77 can support the semiconductor wafer W in a horizontal position.

[0066] 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 horizontal positional deviation of the semiconductor wafer W supported by the plurality of substrate support pins 77.

[0067] In addition, if Figure 2 and Figure 3 As shown, an opening 78 is formed vertically through the holding plate 75 of the base 74. The opening 78 is provided to allow the lower radiation thermometer 20 to receive radiation light (infrared light) emitted from the lower surface of the semiconductor wafer W. Specifically, the lower radiation thermometer 20 receives the light emitted from the lower surface of the semiconductor wafer W via the opening 78 and the transparent window 21 attached to the through hole 61b of the chamber side 61, thereby measuring the temperature of the semiconductor wafer W. Furthermore, four through holes 79 are formed in the holding plate 75 of the base 74, through which the lift pins 12 of the transfer mechanism 10, described below, pass to transfer the semiconductor wafer W.

[0068] Figure 5 : is a top view of the transfer mechanism 10. Figure 6: This is a side view of the transfer mechanism 10. The transfer mechanism 10 includes two transfer arms 11. The transfer arms 11 are formed into an arc shape, such as along the substantially annular recess 62. Two lifting pins 12 are vertically provided on each transfer arm 11. The transfer arms 11 and the lifting pins 12 are formed of quartz. Each transfer arm 11 can be rotated by a horizontal moving mechanism 13. The horizontal moving mechanism 13 enables a pair of transfer arms 11 to be in a transfer action position ( Figure 5 The solid line position) and the retreat position ( Figure 5 The horizontal moving mechanism 13 may be a horizontal moving mechanism 13 that rotates each transfer arm 11 individually by a separate motor, or a horizontal moving mechanism 13 that uses a link mechanism and rotates a pair of transfer arms 11 in conjunction with each other by a single motor.

[0069] In addition, the pair of transfer arms 11 are moved up and down together with the horizontal moving mechanism 13 by the lifting mechanism 14. When the lifting mechanism 14 raises the pair of transfer arms 11 to the transfer operation position, a total of four lifting pins 12 pass through the through holes 79 (refer to Figure 2 、 3 ), the upper end of the lift pin 12 protrudes from the upper surface of the base 74. On the other hand, the lifting mechanism 14 causes the pair of transfer arms 11 to descend in the transfer action position and pulls the lift pin 12 out of the through hole 79. When the horizontal moving mechanism 13 moves the pair of transfer arms 11 to open, each transfer arm 11 moves to a retreat position. The retreat position of the pair of transfer arms 11 is directly above the base ring 71 of the holding portion 7. The base ring 71 is placed on the bottom surface of the recess 62, so the retreat position of the transfer arm 11 becomes the inner side of the recess 62. In addition, an exhaust mechanism (not shown) is also provided near the portion where the drive portion (horizontal moving mechanism 13 and lifting mechanism 14) of the transfer mechanism 10 is provided, and is configured to discharge the gas around the drive portion of the transfer mechanism 10 to the outside of the chamber 6.

[0070] Back to Figure 1 The flash heating unit 5 disposed above the chamber 6 is composed of a light source consisting of a plurality of (30 in this embodiment) xenon flash lamps FL on the inner side of a housing 51, and a reflector 52 disposed to cover the upper side of the light source. In addition, a light irradiation window 53 is installed at the bottom of the housing 51 of the flash heating unit 5. The light irradiation window 53 constituting the bottom plate of the flash heating unit 5 is a plate-shaped quartz window formed of quartz. By arranging the flash heating unit 5 above the chamber 6, the light irradiation window 53 will be opposite to the upper chamber window 63. The flash lamp FL irradiates the heat treatment space 65 with flash light from above the chamber 6 through the light irradiation window 53 and the upper chamber window 63.

[0071] The flash lamps FL are rod-shaped lamps each having an elongated cylindrical shape. They are arranged in a planar shape with their longitudinal directions parallel to each other along the main surface (i.e., in the horizontal direction) of the semiconductor wafer W held by the holding portion 7. Therefore, the plane formed by the arrangement of the flash lamps FL is also a horizontal plane.

[0072] Figure 8 is a diagram showing a driving circuit of the flash lamp FL. As shown in the figure, a capacitor 93, a coil 94, a flash lamp FL, and an IGBT (insulated gate bipolar transistor) 96 are connected in series. Figure 8 As shown, the control unit 3 includes a pulse generator 31 and a waveform setting unit 32, which are connected to an input unit 33. Various well-known input devices such as a keyboard, a mouse, and a touch panel can be used as the input unit 33. The waveform setting unit 32 sets the waveform of the pulse signal based on the input from the input unit 33, and the pulse generator 31 generates the pulse signal according to this waveform.

[0073] Flashlamp FL comprises a rod-shaped glass tube (discharge tube) 92, which contains xenon gas and has an anode and a cathode at each end; and a trigger electrode 91 attached to the outer circumference of glass tube 92. A specific voltage is applied to capacitor 93 by power supply unit 95, charging capacitor 93 with a charge corresponding to the applied voltage (charging voltage). Furthermore, a high voltage can be applied to trigger electrode 91 from trigger circuit 97. The timing at which trigger circuit 97 applies the voltage to trigger electrode 91 is controlled by control unit 3.

[0074] IGBT 96 is a bipolar transistor with a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) integrated into the gate. It is a switching element suitable for handling high power. A pulse signal is applied to the gate of IGBT 96 from pulse generator 31 of control unit 3. When a voltage greater than a specific value (high voltage) is applied to the gate of IGBT 96, IGBT 96 turns on. When a voltage less than a specific value (low voltage) is applied, IGBT 96 turns off. This turns the drive circuit including flash lamp FL on and off according to IGBT 96. Turning IGBT 96 on and off disconnects the flash lamp FL from the corresponding capacitor 93, thus controlling the current flowing to the flash lamp FL.

[0075] Even if IGBT 96 is turned on while capacitor 93 is charged, and a high voltage is applied to the electrodes at both ends of glass tube 92, xenon gas is an electrical insulator, so normally no electricity flows through glass tube 92. However, if trigger circuit 97 applies a high voltage to trigger electrode 91, breaking the insulation, discharge between the electrodes causes current to flow instantaneously through glass tube 92, and the excitation of xenon atoms or molecules at this time causes light emission.

[0076] like Figure 8 The driving circuits shown are individually provided in a plurality of flash lamps FL, which are provided in the flash heating unit 5. In this embodiment, 30 flash lamps FL are arranged in a plane, and therefore, 30 flash lamps including the following are provided corresponding to them. Figure 8 Therefore, the currents flowing to the 30 flash lamps FL are individually controlled to be turned on and off by the corresponding IGBTs 96 .

[0077] Furthermore, a 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 flashlights emitted from the multiple flash lamps FL toward one side of the heat treatment space 65. The reflector 52 is formed from an aluminum alloy plate, and its surface (the side facing the flash lamps FL) has been roughened by sandblasting.

[0078] The halogen heating unit 4, located below the chamber 6, has a plurality (40 in this embodiment) of halogen lamps HL built into a housing 41. The halogen heating unit 4 is a light irradiation unit that heats the semiconductor wafer W by irradiating light from the bottom of the chamber 6 through the lower chamber window 64 into the heat treatment space 65 using the plurality of halogen lamps HL.

[0079] Figure 7 It is a top view showing the configuration of multiple halogen lamps HL. 40 halogen lamps HL are divided into two sections, upper and lower. 20 halogen lamps HL are provided in the upper section close to the holding portion 7, and 20 halogen lamps HL are also provided in the lower section farther away from the holding portion 7 than the upper section. Each halogen lamp HL is a rod-shaped lamp with a long cylindrical shape. The 20 halogen lamps HL in both the upper and lower sections are arranged in parallel with each other along the main surface of the semiconductor wafer W held in the holding portion 7 (i.e., along the horizontal direction) in their respective length directions. Therefore, the plane formed by the arrangement of the halogen lamps HL in both the upper and lower sections is a horizontal plane.

[0080] In addition, if Figure 7As shown, the halogen lamps HL are arranged at a higher density in both the upper and lower sections, facing the periphery of the semiconductor wafer W held by the holding portion 7, compared to the area facing the center. In other words, the spacing between the halogen lamps HL in the periphery is shorter than in the center of the arrangement. This allows the halogen heating unit 4 to provide a greater amount of light to the periphery of the semiconductor wafer W, which is prone to temperature drops, during heating.

[0081] The upper halogen lamps HL and the lower halogen lamps HL are arranged in a grid pattern, so that the longitudinal directions of the 20 halogen lamps HL in the upper and lower sections are perpendicular to each other, for a total of 40 halogen lamps HL.

[0082] The halogen lamp HL is a filament-type light source that emits light by energizing a filament disposed inside a glass tube to turn the filament incandescent. A gas formed by introducing a trace amount of halogen elements (iodine, bromine, etc.) into an inert gas such as nitrogen or argon is sealed inside the glass tube. By introducing the halogen element, it is possible to suppress breakage of the filament and set the temperature of the filament to a high temperature. Therefore, the halogen lamp HL has the characteristics of a long life and the ability to continuously irradiate strong light compared to a conventional incandescent bulb. In other words, the halogen lamp HL is a continuously lit lamp that emits light continuously for at least 1 second. In addition, the halogen lamp HL is a rod-shaped lamp, so it has a long life. By arranging the halogen lamp HL in the horizontal direction, the radiation efficiency toward the semiconductor wafer W above becomes excellent.

[0083] Furthermore, a reflector 43 ( Figure 1 The reflector 43 reflects the light emitted from the plurality of halogen lamps HL to one side of the heat treatment space 65 .

[0084] like Figure 1 As shown, the heat treatment apparatus 1 includes an upper radiation thermometer 25 and a lower radiation thermometer 20. The upper radiation thermometer 25 is positioned obliquely above the semiconductor wafer W held by the susceptor 74 and receives infrared light emitted from the upper surface of the semiconductor wafer W to measure the upper surface temperature. The infrared sensor 29 of the upper radiation thermometer 25 includes an InSb (indium antimonide) optical element to enable it to respond to the sudden temperature change of the upper surface of the semiconductor wafer W at the moment of exposure to the flash light. Meanwhile, the lower radiation thermometer 20 is positioned obliquely below the semiconductor wafer W held by the susceptor 74 and receives infrared light emitted from the lower surface of the semiconductor wafer W to measure the lower surface temperature.

[0085] The control unit 3 controls the various action mechanisms provided in the heat treatment device 1. The hardware structure of the control unit 3 is the same as that of an ordinary computer. That is, the control unit 3 includes a CPU as a circuit for performing various calculations, a ROM as a read-only memory for storing basic programs, a RAM as a freely readable and writable memory for storing various information, and a storage unit (for example, a magnetic disk or SSD) for pre-storing control software or data. The CPU of the control unit 3 executes a specific processing program, thereby performing processing in the heat treatment device 1. In addition, the control unit 3 includes a pulse generator 31 and a waveform setting unit 32 ( Figure 8 ), based on the input content from the input unit 33, the waveform setting unit 32 sets the waveform of the pulse signal, and accordingly, the pulse generator 31 generates a pulse signal that turns the IGBT96 on and off.

[0086] In addition to the aforementioned configuration, the heat treatment apparatus 1 also includes various cooling mechanisms to prevent the heat energy generated by the halogen lamp HL and the flash lamp FL during the heat treatment of the semiconductor wafer W from causing excessive temperature increases in the halogen heating unit 4, the flash heating unit 5, and the chamber 6. For example, a water cooling pipe (not shown) is provided in the wall of the chamber 6. Furthermore, the halogen heating unit 4 and the flash heating unit 5 are air-cooled structures that generate internal gas flows to dissipate heat. Furthermore, air is supplied to the gap between the upper chamber window 63 and the lamp radiation window 53 to cool the flash heating unit 5 and the upper chamber window 63.

[0087] Next, the processing operations in heat treatment apparatus 1 will be described. First, a typical heat treatment sequence for a semiconductor wafer W serving as the processing target will be described. The semiconductor wafer W serving as the processing target here is a silicon semiconductor substrate with a nickel thin film formed on the source and drain regions. Nickel silicide is formed through flash light irradiation heat treatment (annealing) performed by heat treatment apparatus 1. The processing sequence in heat treatment apparatus 1 described below is performed by control of the various operating mechanisms of heat treatment apparatus 1 by control unit 3.

[0088] First, the gas supply valve 84 is opened and the exhaust valves 89 and 192 are opened to start exhausting the gas supply in the chamber 6. When the valve 84 is opened, nitrogen gas is supplied from the gas supply hole 81 to the heat treatment space 65. 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.

[0089] In addition, by opening valve 192, the gas in chamber 6 is also exhausted from transfer opening 66. Furthermore, by using an exhaust mechanism (not shown), the gas around the drive unit of transfer mechanism 10 is also exhausted. In addition, during the heat treatment of semiconductor wafers W in heat treatment apparatus 1, nitrogen gas is continuously supplied to heat treatment space 65, and the supply amount is appropriately changed according to the treatment step.

[0090] Next, gate valve 185 is opened, releasing transfer opening 66, and a transfer robot outside the apparatus carries the semiconductor wafer W, to be processed, into heat treatment space 65 within chamber 6 via transfer opening 66. At this time, as the semiconductor wafer W is carried in, there is a possibility that gas from outside the apparatus will be drawn in. However, since nitrogen gas is continuously supplied to chamber 6, it flows out of transfer opening 66, minimizing the influx of such external gas.

[0091] The semiconductor wafer W loaded by the transfer robot enters a position directly above the holding portion 7 and stops. Next, the pair of transfer arms 11 of the transfer mechanism 10 move horizontally from the retracted position to the transfer operation position and then rise. As a result, the lift pins 12 protrude from the upper surface of the holding plate 75 of the base 74 through the through-holes 79 to receive the semiconductor wafer W. At this time, the lift pins 12 rise to a position higher than the upper ends of the substrate support pins 77.

[0092] After the semiconductor wafer W is placed on the lifting pins 12, the transport robot withdraws from the heat treatment space 65 and closes the transport opening 66 by the gate valve 185. Next, a pair of transfer arms 11 descends, whereby the semiconductor wafer W is transferred from the transfer mechanism 10 to the base 74 of the holding portion 7 and is held in a horizontal position from below. The semiconductor wafer W is supported and held on the base 74 by a plurality of substrate support pins 77 erected on the holding plate 75. In addition, the semiconductor wafer W is held on the holding portion 7 with the surface on which the nickel film is formed as the upper surface. A specific gap is formed between the back surface (the main surface on the opposite side to the 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 have descended to the bottom of the base 74 retreat to the retreat position, i.e., the inner side of the recess 62, by the horizontal moving mechanism 13.

[0093] After the semiconductor wafer W is held horizontally from below by the base 74 of the holding portion 7 formed of quartz, the 40 halogen lamps HL of the halogen heating portion 4 are lit together to start preheating (auxiliary heating). The halogen light emitted from the halogen lamps HL passes through the lower chamber window 64 and the base 74 formed of quartz and irradiates the lower surface of the semiconductor wafer W. By receiving the light irradiation from the halogen lamps HL, the semiconductor wafer W is preheated and the temperature rises. In addition, the transfer arm 11 of the transfer mechanism 10 retreats to the inside of the recess 62, so it does not become an obstacle to the heating of the halogen lamps HL.

[0094] Figure 9 This graph shows the change in the surface temperature of the semiconductor wafer W. At time t1, the halogen lamp HL is turned on, and preheating of the semiconductor wafer W begins. During preheating using the halogen lamp HL, the temperature of the semiconductor wafer W is measured by the lower radiation thermometer 20. Specifically, the lower radiation thermometer 20 receives infrared light emitted from the lower surface of the semiconductor wafer W held on the susceptor 74 through the opening 78 through the transparent window 21 and measures the wafer temperature as it rises. The measured temperature of the semiconductor wafer W is transmitted to the control unit 3. The control unit 3 controls the output of the halogen lamp HL while monitoring whether the temperature of the semiconductor wafer W, which has risen due to light from the halogen lamp HL, has reached a specific preheating temperature T1. Specifically, based on the measurement value obtained by the lower radiation thermometer 20, the control unit 3 performs feedback control on the output of the halogen lamp HL so that the temperature of the semiconductor wafer W reaches the preheating temperature T1. Thus, the lower radiation thermometer 20 is a radiation thermometer used to control the temperature of the semiconductor wafer W during preheating. The preheating temperature T1 is, for example, 850°C.

[0095] After the temperature of the semiconductor wafer W reaches the preheating temperature T1, the control unit 3 temporarily maintains the semiconductor wafer W at the preheating temperature T1. Specifically, at time t2 when the temperature of the semiconductor wafer W 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 substantially at the preheating temperature T1.

[0096] This preheating with the halogen lamps HL uniformly raises the temperature of the entire semiconductor wafer W to the preheating temperature T1. During the preheating stage with the halogen lamps HL, the temperature of the peripheral portion of the semiconductor wafer W, where heat dissipation is more likely to occur, tends to be lower than that of the central portion. However, the density of the halogen lamps HL in the halogen heating unit 4 is higher in the area facing the peripheral portion than in the area facing the central portion of the semiconductor wafer W. Consequently, the amount of light irradiated to the peripheral portion of the semiconductor wafer W, where heat dissipation is more likely to occur, increases, making the in-plane temperature distribution of the semiconductor wafer W more uniform during the preheating stage.

[0097] At time t3, after the temperature of the semiconductor wafer W reaches the preheating temperature T1 and a specific time has passed, the flash lamp FL of the flash heating unit 5 irradiates 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 lamp FL is directly directed into the chamber 6, while the other part is temporarily reflected by the reflector 52 and then directed into the chamber 6. The semiconductor wafer W is flash heated by the irradiation of this flash light.

[0098] When flash lamp FL emits flash light, electric charge is stored in capacitor 93 at a specific charging voltage via power supply unit 95. In this embodiment, capacitor 93 is charged at a charging voltage of 3400 V or less. Then, while electric charge is stored in capacitor 93, pulse generator 31 of control unit 3 outputs a pulse signal to the gate of IGBT 96, thereby turning IGBT 96 on and off.

[0099] The waveform of the pulse signal can be specified, for example, by inputting a recipe from input unit 33, in which the pulse width (on time) and the pulse interval (off time) are sequentially set as parameters. When the operator inputs this recipe from input unit 33 to control unit 3, waveform setting unit 32 of control unit 3 sets a pulse waveform that repeatedly switches on and off. Then, pulse generator 31 generates and outputs a pulse signal in accordance with the pulse waveform set by waveform setting unit 32. This pulse signal is then input to the gate of IGBT 96.

[0100] Figure 10 This is a diagram showing an example of the waveform of the pulse signal input to the IGBT 96. As shown in the figure, the pulse signal of this embodiment is alternately turned on and off repeatedly. In addition, in this embodiment, the period Ts of the pulse signal being turned on and off, that is, the total time of one on time and one off time, is less than 200 microseconds. By applying the following to the gate of the IGBT 96: Figure 10 The pulse signal of the waveform shown controls the on / off driving of the IGBT 96. Specifically, when the pulse signal input to the gate of the IGBT 96 is on, the IGBT 96 is turned on, and when the pulse signal is off, the IGBT 96 is turned off.

[0101] Furthermore, the control unit 3 controls the trigger circuit 97 in synchronization with the timing at which the pulse signal output from the pulse generator 31 turns on, thereby applying a high voltage (trigger voltage) to the trigger electrode 91. While the capacitor 93 is charged, a pulse signal is input to the gate of the IGBT 96, and a high voltage is applied to the trigger electrode 91 in synchronization with the timing at which the pulse signal turns on. Consequently, when the pulse signal turns on, current flows between the two end electrodes in the glass tube 92, and light is emitted due to the excitation of xenon atoms or molecules at this time.

[0102] In this manner, the 30 flash lamps FL of the flash heating unit 5 emit light, illuminating the surface of the semiconductor wafer W held in the holding unit 7 with flash light. When the flash lamps FL are illuminated without using the IGBTs 96, the charge stored in the capacitors 93 is consumed during a single flash, resulting in a simple single-pulse output waveform from the flash lamps FL with a width of approximately 0.1 to 10 milliseconds. In contrast, in this embodiment, by connecting an IGBT 96, a switching element, to the circuit and outputting a pulse signal to its gate, the IGBTs 96 interrupt the supply of charge from the capacitors 93 to the flash lamps FL, thereby controlling the on / off flow of current to the flash lamps FL. As a result, the light emission of the flash lamps FL is controlled in a chopping manner, dividing and consuming the charge stored in the capacitors 93, causing the flash lamps FL to repeatedly flash on and off for extremely short periods of time. Furthermore, before the current flowing through the circuit reaches zero, the next pulse is applied to the gate of the IGBT 96, causing the current to increase again. Therefore, the light output of the flash lamps FL does not completely reach zero even while the flash lamps FL are repeatedly flashing on and off.

[0103] By using the IGBT 96 to control the on / off flow of current to the flash lamp FL, the flash lamp FL's emission pattern (the temporal waveform of the emission output) can be freely defined, allowing for the adjustment of both the emission duration and the intensity of the emission. The on / off drive pattern of the IGBT 96 is determined by the pulse width and pulse interval input from the input unit 33. In other words, simply by integrating the IGBT 96 into the flash lamp FL's drive circuit and appropriately setting the pulse width and pulse interval input from the input unit 33, the flash lamp FL's emission pattern can be freely defined.

[0104] Specifically, for example, increasing the ratio of the pulse width input from input unit 33 to the pulse interval increases the current flowing through flash lamp FL, increasing the intensity of the light emission. Conversely, decreasing the ratio of the pulse width input from input unit 33 to the pulse interval decreases the current flowing through flash lamp FL, decreasing the intensity of the light emission. Furthermore, by appropriately adjusting the ratio of the pulse interval input from input unit 33 to the pulse width, the light emission intensity of flash lamp FL can be maintained constant. Furthermore, by increasing the total duration of the combined pulse width and pulse interval input from input unit 33, current continues to flow through flash lamp FL for a relatively long period of time, extending the light emission duration of flash lamp FL. The light emission duration of flash lamp FL is appropriately set between 0.1 milliseconds and 100 milliseconds. The maximum surface temperature of semiconductor wafer W and the amount of heat input to semiconductor wafer W are determined by the voltage charged to capacitor 93 and the waveform of the light emission pattern of flash lamp FL.

[0105] In this way, the flash lamp FL irradiates the surface of the semiconductor wafer W with flash light for an irradiation time of 0.1 milliseconds to 100 milliseconds (10 milliseconds in this embodiment) to flash heat the semiconductor wafer W. Then, the surface temperature of the semiconductor wafer W, which has been flash-heated by the flash light from the flash lamp FL, instantly rises to the processing temperature T2. It takes about 10 milliseconds for the surface of the semiconductor wafer W to heat up to the processing temperature T2, whereby the nickel thin film reacts with silicon to form nickel silicide. The processing temperature T2 is, for example, 1250°C. After the surface temperature of the semiconductor wafer W reaches the processing temperature T2 at time t4, the pulse signal does not turn on, the flash lamp FL stops emitting light, and the surface temperature drops rapidly. In this way, in the heat treatment apparatus 1, by irradiating with flash light for an extremely short irradiation time, the surface temperature of the semiconductor wafer W can be raised or lowered in an extremely short time.

[0106] After the flash heating treatment is completed, the halogen lamp HL is also extinguished. As a result, the semiconductor wafer W is rapidly cooled from the preheating temperature T1. The temperature of the semiconductor wafer W during cooling 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 dropped to a specific temperature based on the measurement result of the lower radiation thermometer 20. Then, after the temperature of the semiconductor wafer W drops below the specific temperature, the pair of transfer arms 11 of the transfer mechanism 10 moves horizontally from the retreat position to the transfer action position again and rises, thereby causing the lift pins 12 to protrude from the upper surface of the base 74 and receive the heat-treated semiconductor wafer W from the base 74. Subsequently, the transport opening 66 closed by the gate valve 185 is opened, and the semiconductor wafer W placed on the lift pins 12 is moved out by the transport robot outside the device, and the heating treatment of the semiconductor wafer W in the heat treatment device 1 is completed.

[0107] Figure 11 is a diagram showing the change in surface temperature of a semiconductor wafer W during flash heating. Figure 9 The time from time t3 to time t4 is amplified. The time from time t3 to time t4 is approximately 10 milliseconds. The IGBT 96 is repeatedly turned on and off according to the waveform of the pulse signal output from the pulse generator 31. As a result, the current flowing to the flash lamp FL also repeatedly increases and decreases. As a result, the intensity of the light emitted from the flash lamp FL also repeatedly increases and decreases. Figure 11 As shown, during the flash heating process from time t3 to time t4 , the surface temperature of the semiconductor wafer W rises from the preheating temperature T1 to the processing temperature T2 while repeating slight increases and decreases.

[0108] In this embodiment, the on-off cycle Ts of the pulse signal output by the pulse generator 31 is set to 200 microseconds or less. Consequently, the on-off cycle of the IGBT 96, when it is repeatedly turned on and off, is also extremely short, at 200 microseconds or less. Consequently, the amplitude of the increase or decrease in the surface temperature of the semiconductor wafer W is also reduced. Specifically, the on-time of the IGBT 96 is extremely short. Therefore, while the IGBT 96 is on, the current flowing to the flash lamp FL increases, and the amplitude of the increase in the surface temperature of the semiconductor wafer W is extremely small. Furthermore, the off-time of the IGBT 96 is also extremely short. Therefore, while the IGBT 96 is off, the current flowing to the flash lamp FL decreases, and the amplitude of the decrease in the surface temperature of the semiconductor wafer W is also extremely small. As a result, the amplitude of the increase or decrease in the surface temperature of the semiconductor wafer W is reduced.

[0109] Figure 12 Graph showing the increase and decrease of the surface temperature of the semiconductor wafer W during flash heating. Figure 11 During the flash heating process, the surface temperature of the semiconductor wafer W repeatedly increases and decreases on a microscopic level while gradually rising on a macroscopic level. Figure 12 1 shows a rough cycle of increase and decrease in the surface temperature of the semiconductor wafer W.

[0110] The on-off cycle of IGBT 96 is extremely short, at 200 microseconds or less. Consequently, the cycle of increase and decrease in the current flowing to flash lamp FL is also extremely short. As a result, the cycle of increase and decrease in the surface temperature of semiconductor wafer W is also reduced to approximately 200 microseconds or less. If the charging voltage of capacitor 93 (i.e., the voltage applied to flash lamp FL) is 3400V or less, and the on-off cycle of IGBT 96 is reduced to 200 microseconds or less, the difference Td between the maximum and minimum values of the surface temperature of semiconductor wafer W within one cycle of increase and decrease is reduced to less than 10°C.

[0111] When the surface temperature of the semiconductor wafer W repeatedly increases and decreases due to the on / off switching of the IGBT 96, thermal expansion and contraction cause repeated stress to act on the semiconductor wafer W. However, if the difference Td between the maximum and minimum surface temperatures of the semiconductor wafer W is 10°C or less, the stress repeatedly acting on the semiconductor wafer W falls below the fatigue limit. Therefore, even if repeated stress acts on the semiconductor wafer W, it does not cause cracks in the semiconductor wafer W. In other words, as in the first embodiment, cracks caused by repeated stress in the semiconductor wafer W can be prevented when irradiated with flash light.

[0112] <Second embodiment>

[0113] Next, a second embodiment of the present invention will be described. The configuration of the heat treatment apparatus and the processing sequence for semiconductor wafers W in the second embodiment are substantially the same as those in the first embodiment. In the second embodiment, the phase of the increase and decrease in intensity of light emitted from a flashlamp FL is reversed from the phase of the increase and decrease in intensity of light emitted from adjacent flashlamp FL.

[0114] In the second embodiment, as in the first embodiment, 30 flash lamps FL are arranged in a horizontal direction in parallel with each other in a planar shape. Figure 8 That is, an IGBT 96 is individually connected in series to each of the 30 flash lamps FL. Therefore, a total of 30 IGBTs 96 are provided in the heat treatment apparatus 1.

[0115] In the second embodiment, the control unit 3 individually controls the on and off of the 30 IGBTs 96. Specifically, the pulse generator 31 of the control unit 3 outputs a pulse signal having a waveform unique to each of the 30 IGBTs 96.

[0116] Any of the 30 flash lamps FL arranged horizontally is designated as the first flash lamp FL, and the lamp adjacent thereto is designated as the second flash lamp FL. Furthermore, the switching element connected to the first flash lamp FL is the first IGBT 96, and the switching element connected to the second flash lamp FL is the second IGBT 96. Therefore, the first IGBT 96 controls the current flowing to the first flash lamp FL, and the second IGBT 96 controls the current flowing to the second flash lamp FL.

[0117] In the second embodiment, the pulse generator 31 outputs pulse signals having different waveforms to the first IGBT 96 and the second IGBT 96 , respectively. Figure 13 : is a diagram showing an example of the waveform of the pulse signal input to the first IGBT 96 and the second IGBT 96 in the second embodiment. Figure 1 3 is output to the first IGBT 96, and the pulse signal Figure 13 The pulse signal shown in the lower section is output to the second IGBT 96 .

[0118] like Figure 13 As shown, the phases of the pulse signal input to the first IGBT 96 and the pulse signal input to the second IGBT 96 are reversed. That is, when the pulse signal input to the first IGBT 96 is on, the pulse signal input to the second IGBT 96 is off. Conversely, when the pulse signal input to the first IGBT 96 is off, the pulse signal input to the second IGBT 96 is on.

[0119] When the flash light is irradiated, the pulse generator 31 will Figure 13 When the pulse signals shown are respectively given to the first IGBT 96 and the second IGBT 96, the first IGBT 96 Figure 13 The second IGBT96 is repeatedly turned on and off according to the waveform of the pulse signal of the upper section. Figure 1 The waveform of the pulse signal in the lower section of FIG3 repeatedly switches on and off. Consequently, when the first IGBT 96 is turned on, the second IGBT 96 is turned off, and when the first IGBT 96 is turned off, the second IGBT 96 is turned on. As a result, the phases of the increase and decrease in the current flowing to the first and second flash lamps FL are reversed, and the phases of the increase and decrease in the intensity of the light emitted from the first and second flash lamps FL are also reversed.

[0120] When the phases of the increase and decrease in the intensity of the light emitted from the adjacent first and second flash lamps FL are reversed, the first and second flash lamps FL cancel each other out. This suppresses the repeated increase and decrease in the intensity of the light irradiating the semiconductor wafer W during flash heating, and the surface temperature of the semiconductor wafer W rises monotonically. As a result, repeated stress is not applied to the semiconductor wafer W during flash heating, preventing cracks in the semiconductor wafer W. In other words, as in the second embodiment, cracks in the semiconductor wafer W caused by repeated stress during flash light irradiation can be prevented. Furthermore, instead of having one first flash lamp FL and one second flash lamp FL, there are 15 each, with the first and second flash lamps FL alternately arranged to form an arrangement of 30 flash lamps FL.

[0121] <Third embodiment>

[0122] Next, the third embodiment of the present invention will be described. The configuration of the heat treatment apparatus and the processing sequence for semiconductor wafers W in the third embodiment are substantially the same as those in the first embodiment. In the third embodiment, as in the second embodiment, the phase of the increase and decrease in the intensity of light emitted from a flash lamp FL is reversed from the phase of the increase and decrease in the intensity of light emitted from adjacent flash lamps FL. This is achieved by individually controlling the on and off of multiple IGBTs 96 in the second embodiment, whereas in the third embodiment, the waveform of the pulse signal is reversed using an inversion circuit.

[0123] In the third embodiment, as in the first embodiment, 30 flash lamps FL are arranged in a horizontal direction in parallel with each other in a planar shape. Figure 8That is, an IGBT 96 is individually connected in series to each of the 30 flash lamps FL. Therefore, a total of 30 IGBTs 96 are provided in the heat treatment apparatus 1.

[0124] As in the second embodiment, any of the 30 flash lamps FL arranged horizontally is designated as the first flash lamp FL, and the lamp adjacent to it is designated as the second flash lamp FL. Furthermore, the switching element connected to the first flash lamp FL is the first IGBT 96, and the switching element connected to the second flash lamp FL is the second IGBT 96. Therefore, the first IGBT 96 controls the current flowing to the first flash lamp FL, and the second IGBT 96 controls the current flowing to the second flash lamp FL. Furthermore, as in the second embodiment, there are 15 first flash lamps FL and 15 second flash lamps FL, and these are arranged alternately to form an array of 30 flash lamps FL.

[0125] Figure 14 This is a diagram showing a driving circuit for the second flash lamp FL in the third embodiment. In the third embodiment, a circuit similar to the first flash lamp FL is provided. Figure 8 On the other hand, for the second flash lamp FL, the following is set: Figure 14 The driving circuit shown.

[0126] exist Figure 14 In, with Figure 8 The same elements are marked with the same symbols. Figure 14 The circuit shown is Figure 8 The difference is that an inversion circuit 99 is provided. Specifically, an inversion circuit 99 is provided between the gate of the IGBT 96 and the pulse generator 31 of the control unit 3. The inversion circuit 99 inverts the polarity of the input signal and outputs it. The inversion circuit 99 is, for example, an operational amplifier. Figure 14 In the circuit, except for the inverting circuit 99, the remaining components are the same as Figure 8 same.

[0127] In the third embodiment, the pulse generator 31 of the control unit 3 outputs a pulse signal with a common waveform (i.e., the same waveform) to all 30 IGBTs 96. The pulse signal output from the pulse generator 31 is directly input to the first IGBT 96. Therefore, a pulse signal with the same waveform as the pulse signal output from the pulse generator 31 is input to the first IGBT 96. On the other hand, the pulse signal output from the pulse generator 31 is inverted by the inversion circuit 99 and input to the second IGBT 96. Therefore, a pulse signal with a waveform inverted from the pulse signal output from the pulse generator 31 is input to the second IGBT 96. For example, assuming that the pulse generator 31 outputs the following Figure 13The pulse signal shown in the upper part of the figure will be input to the first IGBT96 Figure 13 The pulse signal shown in the upper part of the figure is input to the second IGBT96 as shown in the figure below. Figure 13 The pulse signal is shown in the lower part.

[0128] Thus, in the third embodiment, as in the second embodiment, the phases of the pulse signals input to the first IGBT 96 and the second IGBT 96 are reversed during flashlight illumination. Consequently, when the first IGBT 96 is on, the second IGBT 96 is off, and when the first IGBT 96 is off, the second IGBT 96 is on. As a result, the phases of the increase and decrease in current flowing to the first and second flashlights FL are reversed, and the phases of the increase and decrease in the intensity of the light emitted from the first flashlight FL are reversed from the phases of the increase and decrease in the intensity of the light emitted from the second flashlight FL. Consequently, as in the second embodiment, the first and second flashlights FL cancel each other out in terms of the intensity of the light emitted.

[0129] Even during the flash heating process, as in the third embodiment, the intensity of the light irradiating the semiconductor wafer W is suppressed from repeatedly increasing and decreasing, and the surface temperature of the semiconductor wafer W increases monotonically. As a result, during the flash heating process, repeated stress is not applied to the semiconductor wafer W, and cracks in the semiconductor wafer W can be prevented. In other words, the third embodiment can prevent cracks in the semiconductor wafer W caused by repeated stress during flash light irradiation.

[0130] <Example of variation>

[0131] While the embodiments of the present invention have been described above, various modifications other than those described above are possible without departing from the spirit of the present invention. For example, the first embodiment described above can be combined with the second or third embodiment. Specifically, the on-off cycle of the IGBT 96 can be set to 200 microseconds or less, and the phases of the increase and decrease in the intensity of the light emitted from adjacent flash lamps FL can be reversed. This can more reliably prevent cracks in the semiconductor wafer W caused by repeated stress during flash light irradiation.

[0132] Furthermore, in the second and third embodiments, the phases of increase and decrease in the intensity of light emitted from the adjacent first and second flash lamps FL are reversed. However, this is not limiting. The first and second flash lamps FL can be any flash lamps FL among the plurality of flash lamps FL provided in the flash heating unit 5. For example, the first and second flash lamps FL can be used in the right and left halves of the array of 30 flash lamps FL. However, by placing the first and second flash lamps FL adjacent to each other as in the second and third embodiments, the effect of canceling out the differences in the intensity of the light emitted by them can be achieved most efficiently.

[0133] In addition, in each of the above embodiments, an IGBT 96 is used as a switching element, but this is not limiting. For example, a GTO (Gate Turn Off) thyristor or a GCT (Gate Commutated Turn Off) thyristor may also be used as a switching element. GTO thyristors and GCT thyristors have a self-arc extinguishing function, which allows them to switch from an on state to an off state by applying a negative signal to the gate. Furthermore, as a basic function of a thyristor, GTO thyristors and GCT thyristors have a function of switching from an off state to an on state by applying a positive signal to the gate. In other words, GTO thyristors and GCT thyristors are turned on and off by a signal applied to the gate.

[0134] In the third embodiment, an operational amplifier is used as the inverting circuit 99 , but the present invention is not limited thereto. The inverting circuit 99 may be, for example, a NOT circuit.

[0135] In the above embodiment, the flash heating unit 5 includes 30 flash lamps FL. However, this is not a limitation and the number of flash lamps FL can be any number. Furthermore, the flash lamps FL are not limited to xenon flash lamps and can also be krypton flash lamps. Furthermore, the number of halogen lamps HL included in the halogen heating unit 4 is not limited to 40 and can be any number.

[0136] In addition, in the embodiment, a filament-type halogen lamp HL is used as a continuous-lighting lamp that emits light continuously for more than 1 second to preheat the semiconductor wafer W, but this is not limited to this. 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 for preheating.

[0137] [Explanation of Symbols]

[0138] 1: Heat treatment device

[0139] 3: Control Department

[0140] 4: Halogen heating unit

[0141] 5: Flash heating unit

[0142] 6: Chamber

[0143] 7: Maintaining the

[0144] 10: Transfer mechanism

[0145] 20: Lower radiation thermometer

[0146] 25: Upper radiation thermometer

[0147] 31: Pulse generator

[0148] 32: Waveform setting section

[0149] 33: Input

[0150] 63: Upper chamber window

[0151] 64: Lower chamber window

[0152] 65: Heat treatment space

[0153] 74: Base

[0154] 93: Capacitor

[0155] 96: IGBT

[0156] 99: Inverting Circuit

[0157] FL: Flash

[0158] HL: Halogen lamp

[0159] W: semiconductor wafer.

Claims

1. A heat treatment method for heating a substrate by irradiating the substrate with light, comprising: a preheating step of irradiating light onto the substrate by continuously lighting the lamp to heat the substrate to a specific preheating temperature; as well as a flash heating step of irradiating flash light from a plurality of flash lamps onto the surface of the substrate after the preheating step, thereby heating the surface of the substrate to a specific processing temperature; and In the flash heating step, the current flowing to the plurality of flash lamps is controlled by a switching element. In the flash heating step, a cycle of turning on and off the switching element is set to 200 microseconds or less.

2. The heat treatment method according to claim 1, wherein In the flash heating step, a voltage of 3400 V or less is applied to the plurality of flash lamps.

3. The heat treatment method according to claim 2, wherein In the flash heating step, a difference between a maximum value and a minimum value of the surface temperature of the substrate caused by turning on and off the switching element is set to 10° C. or less.

4. The heat treatment method according to any one of claims 1 to 3, wherein The plurality of flashlights include a first flashlight and a second flashlight, In the flash heating step, the current flowing to the first flash lamp is controlled by the first switching element, and the current flowing to the second flash lamp is controlled by the second switching element. In the flash heating step, the second switching element is turned off when the first switching element is turned on, and the second switching element is turned on when the first switching element is turned off.

5. A heat treatment method for heating a substrate by irradiating the substrate with light, comprising: a preheating step of irradiating light onto the substrate by continuously lighting the lamp to heat the substrate to a specific preheating temperature; as well as a flash heating step of irradiating flash light from a plurality of flash lamps onto the surface of the substrate after the preheating step, thereby heating the surface of the substrate to a specific processing temperature; and The plurality of flashlights include a first flashlight and a second flashlight, In the flash heating step, the current flowing to the first flash lamp is controlled by the first switching element, and the current flowing to the second flash lamp is controlled by the second switching element. In the flash heating step, the second switching element is turned off when the first switching element is turned on, and the second switching element is turned on when the first switching element is turned off.

6. The heat treatment method according to claim 5, wherein Different pulse signals for turning on and off are individually given to the first switching element and the second switching element.

7. The heat treatment method according to claim 5, wherein A common pulse signal for turning on and off is applied to the first switching element and the second switching element, and the pulse signal applied to the second switching element is inverted by an inverting circuit.

8. A heat treatment apparatus for heating a substrate by irradiating the substrate with light, comprising: a chamber for receiving a substrate; continuously lighting a lamp to irradiate the substrate accommodated in the chamber with light to heat the substrate to a specific preheating temperature; a plurality of flash lamps for irradiating the surface of the substrate heated to the preheating temperature with flash lamps to raise the surface temperature of the substrate to a specific processing temperature; a plurality of switching elements for controlling current flowing to the plurality of flash lamps; as well as a pulse generator for generating a pulse signal for turning on and off the plurality of switching elements; and The on-off cycle of the pulse signal output by the pulse generator to the plurality of switching elements is set to 200 microseconds or less.

9. The heat treatment device according to claim 8, further comprising a capacitor for supplying power to the plurality of flash lamps. The charging voltage of the capacitor is set to 3400V or less.

10. The heat treatment device according to claim 9, wherein The difference between a maximum value and a minimum value of the surface temperature of the substrate caused by turning on and off the plurality of switching elements when irradiating flash light from the plurality of flash lamps is set to 10° C. or less.

11. The heat treatment device according to any one of claims 8 to 10, wherein The plurality of flashlights include a first flashlight and a second flashlight, The plurality of switching elements include a first switching element for controlling a current flowing to the first flash lamp and a second switching element for controlling a current flowing to the second flash lamp. When the flashlight is irradiated, the second switching element is turned off when the first switching element is turned on, and the second switching element is turned on when the first switching element is turned off.

12. A heat treatment apparatus for heating a substrate by irradiating the substrate with light, comprising: a chamber for receiving a substrate; continuously lighting a lamp to irradiate the substrate accommodated in the chamber with light to heat the substrate to a specific preheating temperature; a plurality of flash lamps for irradiating the surface of the substrate heated to the preheating temperature with flash lamps to raise the surface temperature of the substrate to a specific processing temperature; a plurality of switching elements for controlling current flowing to the plurality of flash lamps; as well as a pulse generator for generating a pulse signal for turning on and off the plurality of switching elements; and The plurality of flashlights include a first flashlight and a second flashlight, The plurality of switching elements include a first switching element for controlling a current flowing to the first flash lamp and a second switching element for controlling a current flowing to the second flash lamp. When the flashlight is irradiated, the second switching element is turned off when the first switching element is turned on, and the second switching element is turned on when the first switching element is turned off.

13. The heat treatment device according to claim 12, wherein The pulse generator outputs different pulse signals to the first switching element and the second switching element, respectively.

14. The heat treatment device according to claim 12, wherein The pulse generator outputs a common pulse signal to the first switching element and the second switching element. The heat treatment device further includes an inversion circuit that inverts the pulse signal applied to the second switching element.

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