JP2012191110A - Thermal treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal treatment device capable of restraining vibrations of a substrate immediately after flash light radiation.SOLUTION: A tip end 72a of a L-sectioned coupling part 72 is welded and fastened to a peripheral edge of a disc-shaped susceptor 74. Meanwhile, a base end 72b of the coupling part 72 is welded and fastened to an annular base ring 71. The base ring 71, the coupling part 72 and the susceptor 74 are all formed of quartz. The peripheral edge of the susceptor 74 and the base ring 71 are fastened to the both ends of the L-sectioned coupling part 72, and therefore, stress rapidly applied to the susceptor 74 and a semiconductor wafer held by the susceptor 74 can be mitigated by flash light radiation, and vibrations of the semiconductor wafer and the susceptor 74 can be restrained immediately after the flash light radiation.

Description

  The present invention relates to a heat treatment apparatus for heating a thin plate-shaped precision electronic substrate (hereinafter simply referred to as “substrate”) such as a semiconductor wafer or a glass substrate for a liquid crystal display device by irradiating flash light.

  In the semiconductor device manufacturing process, impurity introduction is an indispensable step for forming a pn junction in a semiconductor wafer. Currently, impurities are generally introduced by ion implantation and subsequent annealing. The ion implantation method is a technique in which impurity elements such as boron (B), arsenic (As), and phosphorus (P) are ionized and collided with a semiconductor wafer at a high acceleration voltage to physically perform impurity implantation. The implanted impurities are activated by annealing. At this time, if the annealing time is about several seconds or more, the implanted impurities are deeply diffused by heat, and as a result, the junction depth becomes deeper than required, and there is a possibility that good device formation may be hindered.

  Therefore, in recent years, flash lamp annealing (FLA) has attracted attention as an annealing technique for heating a semiconductor wafer in an extremely short time. Flash lamp annealing is a semiconductor wafer in which impurities are implanted by irradiating the surface of the semiconductor wafer with flash light using a xenon flash lamp (hereinafter, simply referred to as “flash lamp” means xenon flash lamp). Is a heat treatment technique for raising the temperature of only the surface of the material in a very short time (several milliseconds or less).

  The radiation spectral distribution of a xenon flash lamp ranges from the ultraviolet region to the near infrared region, has a shorter wavelength than the conventional halogen lamp, and almost coincides with the fundamental absorption band of a silicon semiconductor wafer. Therefore, when the semiconductor wafer is irradiated with flash light from the xenon flash lamp, the semiconductor wafer can be rapidly heated with little transmitted light. Further, it has been found that if the flash light irradiation is performed for a very short time of several milliseconds or less, only the vicinity of the surface of the semiconductor wafer can be selectively heated. For this reason, if the temperature is raised for a very short time by the xenon flash lamp, only the impurity activation can be performed without deeply diffusing the impurities.

  As a heat treatment apparatus using such a xenon flash lamp, in Patent Documents 1 and 2, a pulse emitting lamp such as a flash lamp is arranged on the front side of a semiconductor wafer, and a continuous lighting lamp such as a halogen lamp is arranged on the back side. And what performs desired heat processing by those combination is disclosed. In the heat treatment apparatuses disclosed in Patent Documents 1 and 2, the semiconductor wafer is preheated to a certain temperature with a halogen lamp or the like, and then heated to a desired processing temperature by pulse heating from a flash lamp.

JP-A-60-258928 JP 2005-527972 A

  However, in a heat treatment apparatus using a xenon flash lamp, the surface temperature of the semiconductor wafer rises rapidly in an instant because light having extremely high energy is instantaneously irradiated onto the semiconductor wafer. As a result, a rapid thermal expansion occurs on the surface of the semiconductor wafer and its surrounding atmosphere, causing a problem that the semiconductor wafer and the holding member holding the semiconductor wafer vibrate vigorously immediately after the flash light irradiation. When the semiconductor wafer and the holding member vibrate vigorously, in the worst case, the semiconductor wafer may fall from the holding member or the semiconductor wafer may be broken.

  This invention is made | formed in view of the said subject, and it aims at providing the heat processing apparatus which can suppress the vibration of the board | substrate just after flash light irradiation.

  In order to solve the above-mentioned problems, a first aspect of the present invention is a heat treatment apparatus for heating a substrate by irradiating the substrate with flash light, and a chamber for accommodating the substrate, and placing the substrate in the chamber. A flat plate-shaped susceptor to be held, a base supported by the wall surface of the chamber, a plurality of connecting members for connecting a peripheral edge of the susceptor and the base, and a substrate held by the susceptor. A vertical lamp including a straight line connecting the center of the susceptor in a horizontal position and the peripheral portion, and a flash lamp for irradiating light, and a light irradiation means for preheating the substrate held by the susceptor by light irradiation. The cross-section of the connecting member cut in this way is L-shaped, and the connecting member is fixed to the peripheral edge of the susceptor at the L-shaped tip. Moni, characterized in that it is secured to the base at the proximal end portion of the L-shape.

  According to a second aspect of the present invention, in the heat treatment apparatus according to the first aspect of the present invention, the connecting member is formed of a heat insulating material.

  According to a third aspect of the present invention, in the heat treatment apparatus according to the second aspect of the present invention, the connecting member is made of quartz.

  According to a fourth aspect of the invention, in the heat treatment apparatus according to the second or third aspect of the invention, the connecting member is formed of the same material as the susceptor and the base.

  The invention of claim 5 is the heat treatment apparatus according to any one of claims 1 to 4, wherein the width of the connecting member along the direction perpendicular to the vertical surface is 3 mm or more and 40 mm or less, The thickness of the thinnest part of the connecting member is 3 mm or more and 35 mm or less.

  According to a sixth aspect of the present invention, in the heat treatment apparatus according to any one of the first to fifth aspects, the base has an annular shape.

  According to the first to sixth aspects of the present invention, the connecting member is fixed to the peripheral portion of the susceptor at the L-shaped distal end of the cross section, and the base at the L-shaped proximal end. Since it is fixed, the stress acting rapidly on the susceptor and the substrate held by the flash light irradiation can be relieved, and the vibration of the substrate immediately after the flash light irradiation can be suppressed.

  In particular, according to the invention of claim 2, since the connecting member is formed of a heat insulating material, the heat conduction generated between the wall surface of the chamber and the substrate can be suppressed, and regardless of the temperature of the chamber wall surface, The substrate can be heated to a constant temperature.

  In particular, according to the invention of claim 4, since the connecting member is made of the same material as the susceptor and the base, their thermal expansion coefficients are the same, which is caused by temperature changes when the substrate is heated and cooled. Damage is less likely to occur.

  In particular, according to the invention of claim 6, since the base has an annular shape, the connecting member and the susceptor can be stably supported.

It is a longitudinal cross-sectional view which shows the structure of the heat processing apparatus which concerns on this invention. It is a perspective view which shows the whole external appearance of a holding | maintenance part. It is the top view which looked at the holding | maintenance part from the upper surface. It is the side view which looked at the holding | maintenance part from the side. It is the figure which expanded the vicinity of the connection part of a holding | maintenance part. It is a top view of a connection part. It is a top view of a transfer mechanism. It is a side view of a transfer mechanism. It is a top view which shows arrangement | positioning of a some halogen lamp. It is a flowchart which shows the process sequence of the semiconductor wafer in the heat processing apparatus of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a longitudinal sectional view showing a configuration of a heat treatment apparatus 1 according to the present invention. The heat treatment apparatus 1 of this embodiment is a flash lamp annealing apparatus that heats a semiconductor wafer W by irradiating flash light onto a disk-shaped semiconductor wafer W having a diameter of 300 mm as a substrate. Impurities are implanted into the semiconductor wafer W before being carried into the heat treatment apparatus 1, and an activation process of the impurities implanted by the heat treatment by the heat treatment apparatus 1 is executed.

  The heat treatment apparatus 1 includes a chamber 6 that accommodates a semiconductor wafer W, a flash heating unit 5 that houses a plurality of flash lamps FL, a halogen heating unit 4 that houses a plurality of halogen lamps HL, and a shutter mechanism 2. . A flash heating unit 5 is provided on the upper side of the chamber 6, and a halogen heating unit 4 is provided on the lower side. The heat treatment apparatus 1 includes a holding unit 7 that holds the semiconductor wafer W in a horizontal posture inside the chamber 6, and a transfer mechanism 10 that transfers the semiconductor wafer W between the holding unit 7 and the outside of the apparatus, Is provided. Further, the heat treatment apparatus 1 includes a control unit 3 that controls the operation mechanisms provided in the shutter mechanism 2, the halogen heating unit 4, the flash heating unit 5, and the chamber 6 to perform the heat treatment of the semiconductor wafer W.

  The chamber 6 is configured by mounting quartz chamber windows above and below a cylindrical chamber side portion 61. The chamber side portion 61 has a substantially cylindrical shape with upper and lower openings. The upper opening is closed by an upper chamber window 63 and the lower opening is closed by a lower chamber window 64. ing. The upper chamber window 63 constituting the ceiling of the chamber 6 is a disk-shaped member made of quartz and functions as a quartz window that transmits the flash light emitted from the flash heating unit 5 into the chamber 6. The lower chamber window 64 constituting the floor portion of the chamber 6 is also a disk-shaped member made of quartz and functions as a quartz window that transmits light from the halogen heating unit 4 into the chamber 6.

  A reflection ring 68 is attached to the upper part of the inner wall surface of the chamber side part 61, and a reflection ring 69 is attached to the lower part. The reflection rings 68 and 69 are both formed in an annular shape. The upper reflecting ring 68 is attached by fitting from above the chamber side portion 61. On the other hand, the lower reflection ring 69 is mounted by being fitted from the lower side of the chamber side portion 61 and fastened with a screw (not shown). That is, the reflection rings 68 and 69 are both detachably attached to the chamber side portion 61. An inner space of the chamber 6, that is, a 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 a heat treatment space 65.

  By attaching the reflection rings 68 and 69 to the chamber side portion 61, a recess 62 is formed on the inner wall surface of the chamber 6. That is, a recess 62 surrounded by a central portion of the inner wall surface of the chamber side portion 61 where the reflection rings 68 and 69 are not mounted, a lower end surface of the reflection ring 68, and an upper end surface of the reflection ring 69 is formed. . 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 reflection rings 68 and 69 are formed of a metal material (for example, stainless steel) having excellent strength and heat resistance. Further, the inner peripheral surfaces of the reflection rings 68 and 69 are mirrored by electrolytic nickel plating.

  The chamber side 61 is formed with a transfer opening (furnace port) 66 for carrying the semiconductor wafer W into and out of the chamber 6. The transfer opening 66 can be opened and closed by a gate valve 185. The transport 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 is carried into the heat treatment space 65 through the recess 62 from the transfer opening 66 and the semiconductor wafer W is carried out from the heat treatment space 65. It can be performed. Further, when the gate valve 185 closes the transfer opening 66, the heat treatment space 65 in the chamber 6 becomes a sealed space.

Further, a gas supply hole 81 for supplying a processing gas (nitrogen gas (N ₂ ) in the present embodiment) to the heat treatment space 65 is formed in the upper portion of the inner wall of the chamber 6. The gas supply hole 81 is formed at a position above the recess 62 and may be provided in the reflection ring 68. The gas supply hole 81 is connected to a gas supply pipe 83 through a buffer space 82 formed in an annular shape inside the side wall of the chamber 6. The gas supply pipe 83 is connected to a nitrogen gas supply source 85. A valve 84 is inserted in the middle of the path of the gas supply pipe 83. When the valve 84 is opened, nitrogen gas is supplied from the nitrogen gas supply source 85 to the buffer space 82. The nitrogen gas flowing into the buffer space 82 flows so as to expand in the buffer space 82 having a smaller fluid resistance than the gas supply hole 81 and is supplied from the gas supply hole 81 into the heat treatment space 65.

  On the other hand, a gas exhaust hole 86 for exhausting the gas in the heat treatment space 65 is formed in the lower portion of the inner wall of the chamber 6. The gas exhaust hole 86 is formed at a position lower than the recess 62 and may be provided in the reflection ring 69. The gas exhaust hole 86 is connected to a gas exhaust pipe 88 through a buffer space 87 formed in an annular shape inside the side wall of the chamber 6. The gas exhaust pipe 88 is connected to the exhaust unit 190. 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 to the gas exhaust pipe 88 through the buffer space 87. A plurality of gas supply holes 81 and gas exhaust holes 86 may be provided along the circumferential direction of the chamber 6 or may be slit-shaped. Further, the nitrogen gas supply source 85 and the exhaust unit 190 may be a mechanism provided in the heat treatment apparatus 1 or may be a utility of a factory where the heat treatment apparatus 1 is installed.

  A gas exhaust pipe 191 that exhausts the gas in the heat treatment space 65 is also connected to the tip 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.

  FIG. 2 is a perspective view showing the overall appearance of the holding unit 7. FIG. 3 is a plan view of the holding unit 7 as viewed from above, and FIG. 4 is a side view of the holding unit 7 as viewed from the side. The holding part 7 includes a base ring 71, a connecting part 72, and a susceptor 74. The base ring 71, the connecting portion 72, and the susceptor 74 are all made of quartz. That is, the whole holding part 7 is made of quartz.

  The base ring 71 is an annular quartz member. 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 FIG. 1). On the upper surface of the base ring 71 having an annular shape, a plurality of connecting portions 72 (four in this embodiment) are erected along the circumferential direction. The connecting portion 72 is also a quartz member, and is fixed to the base ring 71 by welding.

  The flat susceptor 74 is supported by four connecting portions 72 provided on the base ring 71. The susceptor 74 is a substantially circular flat plate member made of quartz. The diameter of the susceptor 74 is larger than the diameter of the semiconductor wafer W. That is, the susceptor 74 has a larger planar size than the semiconductor wafer W. On the upper surface of the susceptor 74, a plurality (five in this embodiment) of guide pins 76 are erected. The five guide pins 76 are provided along a circumference that is concentric with the outer circumference of the susceptor 74. The diameter of the circle in which the five guide pins 76 are arranged is slightly larger than the diameter of the semiconductor wafer W. Each guide pin 76 is also formed of quartz. The guide pin 76 may be processed from a quartz ingot integrally with the susceptor 74, or a separately processed one may be attached to the susceptor 74 by welding or the like.

  The four connecting portions 72 erected on the base ring 71 and the lower surface of the peripheral portion of the susceptor 74 are fixed by welding. That is, the susceptor 74 and the base ring 71 are fixedly connected by the connecting portion 72, and the holding portion 7 is an integrally formed member of quartz. When the base ring 71 of the holding unit 7 is supported on the wall surface of the chamber 6, the holding unit 7 is attached to the chamber 6. In a state in which the holding unit 7 is mounted on the chamber 6, the substantially disc-shaped susceptor 74 is in a horizontal posture (a posture in which the normal line matches the vertical direction). The semiconductor wafer W carried into the chamber 6 is placed and held in a horizontal posture on the susceptor 74 of the holding unit 7 attached to the chamber 6. The semiconductor wafer W is placed inside a circle formed by the five guide pins 76, thereby preventing a horizontal displacement. Note that the number of guide pins 76 is not limited to five, and may be any number that can prevent misalignment of the semiconductor wafer W.

  As shown in FIGS. 2 and 3, the susceptor 74 has an opening 78 and a notch 77 penetrating vertically. The notch 77 is provided to pass the probe tip of the contact thermometer 130 using a thermocouple. On the other hand, the opening 78 is provided to receive radiation light (infrared light) emitted from the lower surface of the semiconductor wafer W held by the susceptor 74 by the radiation thermometer 120. Further, the susceptor 74 is provided with four through holes 79 through which lift pins 12 of the transfer mechanism 10 to be described later penetrate for the delivery of the semiconductor wafer W.

  FIG. 5 is an enlarged view of the vicinity of the connecting portion 72 of the holding portion 7. FIG. 6 is a plan view of the connecting portion 72. 5 and 6 show one of the four connecting portions 72, the same applies to any of the connecting portions 72. As shown in FIG. 5, the cross section of the connecting portion 72 cut along a vertical plane including a straight line (that is, the diameter of the susceptor 74) connecting the center and the peripheral edge of the susceptor 74 in a horizontal posture is L-shaped. The connecting portion 72 is welded and fixed to the peripheral portion of the susceptor 74 at the L-shaped tip portion 72a, and is welded and fixed to the base ring 71 at the L-shaped base end portion 72b. The For this reason, the base ring 71 and the connecting portion 72 are not displaced by sliding, and the susceptor 74 and the connecting portion 72 do not slide relative to each other.

  The thickness t (wall thickness) of the thinnest part of the connecting portion 72 is 3 mm or more and 35 mm or less, and is 8 mm in this embodiment. The width d of the connecting portion 72 along the direction perpendicular to the vertical surface (the circumferential direction of the susceptor 74) is 3 mm or more and 40 mm or less, and is 18 mm in this embodiment.

  As described above, in the present embodiment, all of the base ring 71, the connecting portion 72, and the susceptor 74 are made of quartz. That is, the connecting portion 72 is formed of the same material as the susceptor 74 and the base ring 71. Quartz is a heat insulating material that has a relatively low thermal conductivity and suppresses thermal conduction.

  A transfer mechanism 10 is provided below the holding unit 7. FIG. 7 is a plan view of the transfer mechanism 10. FIG. 8 is a side view of the transfer mechanism 10. The transfer mechanism 10 includes two transfer arms 11. The transfer arm 11 has an arc shape that follows the generally annular recess 62. Two lift pins 12 are erected on each transfer arm 11. Each transfer arm 11 can be rotated by a horizontal movement mechanism 13. The horizontal moving mechanism 13 includes a transfer operation position (solid line position in FIG. 7) for transferring the pair of transfer arms 11 to the holding unit 7 and the semiconductor wafer W held by the holding unit 7. It is moved horizontally between the retracted positions (two-dot chain line positions in FIG. 7) that do not overlap in plan view. As the horizontal movement mechanism 13, each transfer arm 11 may be rotated by an individual motor, or a pair of transfer arms 11 may be interlocked by a single motor using a link mechanism. It may be moved.

  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 elevating mechanism 14 raises the pair of transfer arms 11 at the transfer operation position, a total of four lift pins 12 pass through through holes 79 (see FIGS. 2 and 3) formed in the susceptor 74, and the lift pins The upper end of 12 protrudes from the upper surface of the susceptor 74. On the other hand, when the elevating mechanism 14 lowers the pair of transfer arms 11 at the transfer operation position, the lift pins 12 are extracted from the through holes 79, and the horizontal movement mechanism 13 moves the pair of transfer arms 11 so as to open each of them. The transfer arm 11 moves to the retracted position. The retracted position of the pair of transfer arms 11 is directly above the base ring 71 of the holding unit 7. Since the base ring 71 is placed on the bottom surface of the recess 62, the retracted position of the transfer arm 11 is inside the recess 62. Note that an exhaust mechanism (not shown) is also provided in the vicinity of a portion where the drive unit (the horizontal movement mechanism 13 and the lifting mechanism 14) of the transfer mechanism 10 is provided, and the atmosphere around the drive unit of the transfer mechanism 10 is provided. Is discharged to the outside of the chamber 6.

  Returning to FIG. 1, the flash heating unit 5 provided above the chamber 6 includes a light source including a plurality of (30 in the present embodiment) xenon flash lamps FL inside the housing 51, and an upper part of the light source. And a reflector 52 provided so as to cover. A lamp light emission window 53 is mounted on the bottom of the casing 51 of the flash heating unit 5. The lamp light emission window 53 constituting the floor of the flash heating unit 5 is a plate-like quartz window made of quartz. By installing the flash heating unit 5 above the chamber 6, the lamp light emission window 53 faces the upper chamber window 63. The flash lamp FL irradiates 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.

  Each of the plurality of flash lamps FL is a rod-like lamp having a long cylindrical shape, and the longitudinal direction of each of the flash lamps FL is along the main surface of the semiconductor wafer W held by the susceptor 74 (that is, along the horizontal direction). They are arranged in a plane so as to be parallel. Therefore, the plane formed by the arrangement of the flash lamps FL is also a horizontal plane.

  The xenon flash lamp FL has a rod-shaped glass tube (discharge tube) in which xenon gas is sealed and an anode and a cathode connected to a capacitor at both ends thereof, and an outer peripheral surface of the glass tube. And a triggered electrode. Since xenon gas is an electrical insulator, electricity does not flow into the glass tube under normal conditions even if electric charges are accumulated in the capacitor. However, when the insulation is broken by applying a high voltage to the trigger electrode, the electricity stored in the capacitor flows instantaneously in the glass tube, and light is emitted by excitation of atoms or molecules of xenon at that time. In such a xenon flash lamp FL, the electrostatic energy previously stored in the capacitor is converted into an extremely short light pulse of 0.1 to 10 milliseconds, so that the continuous lighting such as the halogen lamp HL is possible. It has the characteristic that it can irradiate extremely strong light compared with a light source.

  In addition, the reflector 52 is provided above the plurality of flash lamps FL so as to cover all of them. The basic function of the reflector 52 is to reflect the flash light emitted from the plurality of flash lamps FL toward the heat treatment space 65. The reflector 52 is formed of an aluminum alloy plate, and the surface (the surface facing the flash lamp FL) is roughened by blasting to exhibit a satin pattern.

  A plurality of halogen lamps HL (40 in this embodiment) are built in the halogen heating unit 4 provided below the chamber 6. The plurality of halogen lamps HL irradiate the heat treatment space 65 from below the chamber 6 through the lower chamber window 64. FIG. 9 is a plan view showing the arrangement of a plurality of halogen lamps HL. In the present embodiment, 20 halogen lamps HL are arranged in two upper and lower stages. Each halogen lamp HL is a rod-shaped lamp having a long cylindrical shape. The 20 halogen lamps HL in both the upper and lower stages are arranged so that their longitudinal directions are parallel to each other along the main surface of the semiconductor wafer W held by the holding unit 7 (that is, along the horizontal direction). Yes. Therefore, the plane formed by the arrangement of the halogen lamps HL in both the upper stage and the lower stage is a horizontal plane.

  Further, as shown in FIG. 9, the arrangement density of the halogen lamps HL in the region facing the peripheral portion is higher than the region facing the central portion of the semiconductor wafer W held by the susceptor 74 in both the upper and lower steps. . That is, in both the upper and lower stages, the arrangement pitch of the halogen lamps HL is shorter on the end side than on the center part of the lamp array. For this reason, it is possible to irradiate a larger amount of light to the peripheral portion of the semiconductor wafer W where the temperature is likely to decrease during heating by light irradiation from the halogen heating unit 4.

  Further, the lamp group composed of the upper halogen lamp HL and the lamp group composed of the lower halogen lamp HL are arranged so as to intersect in a lattice pattern. That is, a total of 40 halogen lamps HL are arranged so that the longitudinal direction of the upper halogen lamps HL and the longitudinal direction of the lower halogen lamps HL are orthogonal to each other.

  The halogen lamp HL is a filament-type light source that emits light by making the filament incandescent by energizing the filament disposed inside the glass tube. Inside the glass tube, a gas obtained by introducing a trace amount of a halogen element (iodine, bromine, etc.) into an inert gas such as nitrogen or argon is enclosed. By introducing a halogen element, it is possible to set the filament temperature to a high temperature while suppressing breakage of the filament. Therefore, the halogen lamp HL has a characteristic that it has a longer life than a normal incandescent bulb and can continuously radiate strong light. Further, since the halogen lamp HL is a rod-shaped lamp, it has a long life, and by arranging the halogen lamp HL along the horizontal direction, the radiation efficiency to the upper semiconductor wafer W becomes excellent.

  As shown in FIG. 1, the heat treatment apparatus 1 includes a shutter mechanism 2 on the side of the halogen heating unit 4 and the chamber 6. The shutter mechanism 2 includes a shutter plate 21 and a slide drive mechanism 22. The shutter plate 21 is a plate that is opaque to the halogen light, and is formed of, for example, titanium (Ti). The slide drive mechanism 22 slides the shutter plate 21 along the horizontal direction, and inserts and removes the shutter plate 21 to and from the light shielding position between the halogen heating unit 4 and the holding unit 7. When the slide drive mechanism 22 advances the shutter plate 21, the shutter plate 21 is inserted into the light shielding position (the two-dot chain line position in FIG. 1) between the chamber 6 and the halogen heating unit 4, and the lower chamber window 64 and the plurality of lower chamber windows 64. The halogen lamp HL is cut off. Accordingly, light traveling from the plurality of halogen lamps HL toward the holding portion 7 of the heat treatment space 65 is shielded. Conversely, when the slide drive mechanism 22 retracts the shutter plate 21, the shutter plate 21 retracts from the light shielding position between the chamber 6 and the halogen heating unit 4 and the lower portion of the lower chamber window 64 is opened.

  Further, the control unit 3 controls the various operation mechanisms provided in the heat treatment apparatus 1. The configuration of the control unit 3 as hardware is the same as that of a general computer. That is, the control unit 3 stores a CPU that performs various arithmetic processes, a ROM that is a read-only memory that stores basic programs, a RAM that is a readable and writable memory that stores various information, control software, data, and the like. It is configured with a magnetic disk. The processing in the heat treatment apparatus 1 proceeds as the CPU of the control unit 3 executes a predetermined processing program.

  In addition to the above configuration, the heat treatment apparatus 1 prevents an excessive temperature rise in the halogen heating unit 4, the flash heating unit 5, and the chamber 6 due to thermal energy generated from the halogen lamp HL and the flash lamp FL during the heat treatment of the semiconductor wafer W. Therefore, various cooling structures are provided. For example, the wall of the chamber 6 is provided with a water-cooled tube (not shown). Further, the halogen heating unit 4 and the flash heating unit 5 have an air cooling structure in which a gas flow is formed inside to exhaust heat. Air is also supplied to the gap between the upper chamber window 63 and the lamp light emission window 53 to cool the flash heating unit 5 and the upper chamber window 63.

  Next, a processing procedure for the semiconductor wafer W in the heat treatment apparatus 1 will be described. The semiconductor wafer W to be processed here is a semiconductor substrate to which impurities (ions) are added by an ion implantation method. Activation of the added impurity is performed by flash light irradiation heat treatment (annealing) by the heat treatment apparatus 1. FIG. 10 is a flowchart showing a processing procedure for the semiconductor wafer W in the heat treatment apparatus 1. The processing procedure of the semiconductor wafer W shown below proceeds by the control unit 3 controlling each operation mechanism of the heat treatment apparatus 1.

  First, the air supply valve 84 is opened, and the exhaust valves 89 and 192 are opened to start supply / exhaust to the chamber 6 (step S1). 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. Thereby, 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.

  Further, when the valve 192 is opened, the gas in the chamber 6 is also exhausted from the transfer opening 66. Further, the atmosphere around the drive unit of the transfer mechanism 10 is also exhausted by an exhaust mechanism (not shown). Note that nitrogen gas is continuously supplied to the heat treatment space 65 during the heat treatment of the semiconductor wafer W in the heat treatment apparatus 1, and the supply amount is appropriately changed according to the processing steps of FIG. 10.

  Subsequently, the gate valve 185 is opened to open the transfer opening 66, and the semiconductor wafer W after the ion implantation is transferred into the heat treatment space 65 in the chamber 6 through the transfer opening 66 by a transfer robot outside the apparatus ( Step S2). The semiconductor wafer W carried in by the carrying robot advances to a position directly above the holding unit 7 and stops. Then, when the pair of transfer arms 11 of the transfer mechanism 10 moves horizontally from the retracted position to the transfer operation position and rises, the lift pins 12 protrude from the upper surface of the susceptor 74 through the through holes 79 and the semiconductor wafer W. Receive. Note that the holding unit 7 is mounted in the chamber 6 in advance so that the susceptor 74 is in a horizontal posture by supporting the base ring 71 on the wall surface of the chamber 6.

  After the semiconductor wafer W is placed on the lift pins 12, the transfer robot leaves the heat treatment space 65 and the transfer opening 66 is closed by the gate valve 185. When the pair of transfer arms 11 are lowered, 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 posture. The semiconductor wafer W is held by the susceptor 74 with the ion-implanted surface as the upper surface. The semiconductor wafer W is held inside the five guide pins 76 on the upper surface of the susceptor 74. The pair of transfer arms 11 lowered to below the susceptor 74 is retracted to the retracted position, that is, inside the recess 62 by the horizontal movement mechanism 13.

  After the semiconductor wafer W is held by the quartz susceptor 74 in a horizontal position from below, the 40 halogen lamps HL are turned on all at once and preheating (assist heating) is started (step S3). The halogen light emitted from the halogen lamp HL passes through the lower chamber window 64 and the susceptor 74 made of quartz and is irradiated from the back surface of the semiconductor wafer W. By receiving light from the halogen lamp HL, the semiconductor wafer W is preheated and the temperature rises. Further, among the light emitted from the halogen lamp HL, a part of the light in the infrared region in particular is absorbed by the lower chamber window 64 and the susceptor 74 made of quartz, so that these also slightly increase in temperature. Since the transfer arm 11 of the transfer mechanism 10 is retracted inside the recess 62 that does not overlap the semiconductor wafer W held by the susceptor 74 in plan view, the light irradiated to the semiconductor wafer W from the halogen lamp HL. Is not blocked by the transfer arm 11.

  In the preheating stage, the temperature of the edge portion of the semiconductor wafer W that is more likely to radiate heat tends to be lower than that in the central portion. However, the arrangement density of the halogen lamps HL in the halogen heating portion 4 is The region facing the edge portion is higher than the region facing the central portion. For this reason, the light quantity irradiated to the edge part of the semiconductor wafer W which is easy to generate heat increases, and the in-plane temperature distribution of the semiconductor wafer W in the preheating stage can be made more uniform.

  Furthermore, since the inner peripheral surface of the reflection ring 69 attached to the chamber side portion 61 is a mirror surface, the amount of light reflected toward the edge of the semiconductor wafer W by the inner peripheral surface of the reflection ring 69 increases. The in-plane temperature distribution of the semiconductor wafer W in the preheating stage can be made more uniform.

  Further, the temperature of the wall surface of the chamber 6 hardly increases even when the halogen lamp HL is lit during the preheating stage. Therefore, the base ring 71 of the holding part 7 supported by the wall surface of the chamber 6 is also generally at room temperature. If the heat conduction generated between the base ring 71 and the susceptor 74 at normal temperature is good, the heat conduction from the semiconductor wafer W heated by light irradiation from the halogen lamp HL to the chamber 6 immediately through the holding unit 7. And preheating is inhibited. For this reason, the susceptor 74 and the base ring 71 are connected by a connecting portion 72 formed of quartz which is a heat insulating material. As a result, heat conduction from the semiconductor wafer W to the chamber 6 through the holding unit 7 is suppressed, and the temperature of the semiconductor wafer W is smoothly raised to a predetermined preheating temperature T1 regardless of the temperature of the wall surface of the chamber 6. can do.

  When preheating with the halogen lamp HL is performed, the temperature of the semiconductor wafer W is measured by the contact thermometer 130. That is, a contact thermometer 130 incorporating a thermocouple contacts the lower surface of the semiconductor wafer W held by the susceptor 74 through the notch 77 to measure the temperature of the wafer being heated. The measured temperature of the semiconductor wafer W is transmitted to the control unit 3. The control unit 3 monitors whether or not the temperature of the semiconductor wafer W that is heated by light irradiation from the halogen lamp HL has reached a predetermined preheating temperature T1 (step S4). Note that when the temperature of the semiconductor wafer W is increased by light irradiation from the halogen lamp HL, temperature measurement by the radiation thermometer 120 is not performed. This is because the halogen light irradiated from the halogen lamp HL enters the radiation thermometer 120 as disturbance light, and accurate temperature measurement cannot be performed.

  In the present embodiment, the preheating temperature T1 is set to about 200 ° C. to 800 ° C., preferably about 350 ° C. to 600 ° C., in which impurities added to the semiconductor wafer W are not likely to diffuse due to heat (this embodiment). In the form of 600 ° C.). When it is detected that the temperature of the semiconductor wafer W has reached the preheating temperature T1, the process immediately proceeds to step S5, and flash light is irradiated from the flash lamp FL of the flash heating unit 5 toward the semiconductor wafer W. At this time, a part of the flash light emitted from the flash lamp FL goes directly into the heat treatment space 65, and the other part is once reflected by the reflector 52 and then goes into the heat treatment space 65. Flash heating of the semiconductor wafer W is performed by light irradiation. Since flash heating is performed by flash light irradiation from the flash lamp FL, the surface temperature of the semiconductor wafer W can be increased in a short time.

  That is, the flash light irradiated from the flash lamp FL of the flash heating unit 5 has an irradiation time of about 0.1 to 10 milliseconds, in which the electrostatic energy stored in advance is converted into an extremely short light pulse. It is a very short and strong flash. Then, the surface temperature of the semiconductor wafer W flash-heated by flash light irradiation from the flash lamp FL instantaneously rises to a processing temperature T2 of 1000 ° C. or higher, and the impurities added to the semiconductor wafer W are activated. The surface temperature drops rapidly. As described above, in the heat treatment apparatus 1, the surface temperature of the semiconductor wafer W can be raised and lowered in a very short time, so that the impurities are activated while suppressing diffusion of impurities added to the semiconductor wafer W due to heat. Can do. In addition, since the time required for activation of the added impurity is extremely short compared with the time required for the thermal diffusion, the activation is performed even for a short time in which diffusion of about 0.1 to 10 milliseconds does not occur. Is completed. Also, light irradiation from the halogen lamp HL is continuously performed during flash heating and for a predetermined time thereafter.

  In the heat treatment apparatus 1 of this embodiment, the semiconductor wafer W is preheated to the preheating temperature T1 (600 ° C.) by the halogen lamp HL, and then flash heating is performed by flash irradiation from the flash lamp FL. When the temperature of the semiconductor wafer W reaches 600 ° C. or higher, thermal diffusion of the added impurities may occur, but the halogen lamp HL can raise the temperature of the semiconductor wafer W to 600 ° C. relatively quickly. Impurity diffusion can be minimized. Further, the surface temperature of the semiconductor wafer W can be quickly raised to the processing temperature T2 by performing the flash light irradiation from the flash lamp FL after the temperature of the semiconductor wafer W is raised to the preheating temperature T1.

  After the flash heating is completed, the halogen lamp HL is turned off after a predetermined time has elapsed, and the temperature of the semiconductor wafer W is started to be lowered (step S6). At the same time that the halogen lamp HL is extinguished, the shutter mechanism 2 inserts the shutter plate 21 into the light shielding position between the halogen heating unit 4 and the chamber 6 (step S7). Even if the halogen lamp HL is turned off, the temperature of the filament and the tube wall does not decrease immediately, but radiation heat continues to be radiated from the filament and tube wall that are hot for a while, which prevents the temperature of the semiconductor wafer W from falling. By inserting the shutter plate 21, the radiant heat radiated from the halogen lamp HL immediately after the light is turned off to the heat treatment space 65 is cut off, and the temperature drop rate of the semiconductor wafer W can be increased.

  Further, temperature measurement by the radiation thermometer 120 is started when the shutter plate 21 is inserted into the light shielding position. That is, the radiation thermometer 120 measures the intensity of infrared light radiated from the lower surface of the semiconductor wafer W held by the holding unit 7 through the opening 78 of the susceptor 74 to determine the temperature of the semiconductor wafer W during the temperature drop. taking measurement. The measured temperature of the semiconductor wafer W is transmitted to the control unit 3.

  Although some radiation is continuously emitted from the high-temperature halogen lamp HL immediately after turning off, the radiation thermometer 120 measures the temperature of the semiconductor wafer W when the shutter plate 21 is inserted in the light shielding position. Radiant light traveling from the halogen lamp HL toward the heat treatment space 65 in the chamber 6 is shielded. Therefore, the radiation thermometer 120 can accurately measure the temperature of the semiconductor wafer W held by the susceptor 74 without being affected by ambient light.

  The controller 3 monitors whether or not the temperature of the semiconductor wafer W measured by the radiation thermometer has dropped to a predetermined temperature. Then, after the temperature of the semiconductor wafer W is lowered to a predetermined temperature or lower, the pair of transfer arms 11 of the transfer mechanism 10 is moved horizontally from the retracted position to the transfer operation position again and lifted, whereby the lift pins 12 are moved to the susceptor. The semiconductor wafer W protruding from the upper surface of 74 and subjected to the heat treatment is received from the susceptor 74. Subsequently, the transfer opening 66 closed by the gate valve 185 is opened, and the semiconductor wafer W placed on the lift pins 12 is unloaded by the transfer robot outside the apparatus (step S8), and the semiconductor wafer in the heat treatment apparatus 1 is transferred. The W flash heat treatment is completed.

  By the way, in the above heat treatment step, the surface temperature of the semiconductor wafer W heated by the flash light irradiation from the flash lamp FL instantaneously rises to the processing temperature T2 of 1000 ° C. or more, while the back surface temperature at that moment is preheating. It does not increase so much from the temperature T1. For this reason, rapid thermal expansion occurs only on the wafer surface side, and stress that warps the semiconductor wafer W so that the upper surface is convex is applied. Next, at the moment, the surface temperature of the semiconductor wafer W rapidly decreases, but the back surface temperature also slightly increases due to heat conduction from the front surface to the back surface, so that the semiconductor wafer W has a stress that tends to warp in the opposite direction. Works. Further, rapid thermal expansion occurs in the atmosphere near the surface of the semiconductor wafer W, and stress acts on the semiconductor wafer W and the susceptor 74 from there. As a result, the semiconductor wafer W and the susceptor 74 try to vibrate vigorously immediately after the flash light irradiation.

  In this embodiment, the peripheral portion of the susceptor 74 and the base ring 71 are connected by a connecting portion 72 of quartz having an L-shaped cross section. Although quartz itself is a hard material and does not have a function as an elastic material, the cross-sectional shape of the connecting portion 72 is L-shaped, and the peripheral portion of the susceptor 74 and the base ring 71 are fixed to both ends thereof. Thus, a vibration damping function can be imparted to the quartz connecting portion 72. That is, the stress acting on the susceptor 74 and the semiconductor wafer W held on the susceptor 74 and the semiconductor wafer W held by the quartz connecting portion 72 having an L-shaped cross section can be relieved, and the vibration of the semiconductor wafer W and the susceptor 74 immediately after flash light irradiation Can be suppressed.

  In order to give an appropriate vibration damping function to the quartz connecting portion 72, the width d of the connecting portion 72 is set to 3 mm to 40 mm, and the thickness t of the thinnest portion is set to 3 mm to 35 mm. If the width d of the connecting portion 72 is less than 3 mm, the connecting portion 72 becomes brittle and may be damaged by an impact acting on the semiconductor wafer W and the susceptor 74 when irradiated with flash light. On the other hand, if the width d of the connecting portion 72 exceeds 40 mm, the rigidity of the connecting portion 72 becomes too high and the vibration damping function is lowered, and the vibration of the semiconductor wafer W and the susceptor 74 immediately after the flash light irradiation cannot be sufficiently suppressed. .

  Further, if the thickness t of the thinnest portion of the connecting portion 72 is less than 3 mm, the connecting portion 72 becomes fragile as described above, and there is a possibility that the connecting portion 72 may be damaged during flash light irradiation. On the other hand, if the thickness t exceeds 35 mm, the rigidity of the connecting portion 72 becomes too high as described above, and the damping function is lowered, and the vibration of the semiconductor wafer W and the susceptor 74 immediately after the flash light irradiation is sufficiently suppressed. become unable. For this reason, the width d of the connecting portion 72 is 3 mm or more and 40 mm or less, and the thickness t of the thinnest part is 3 mm or more and 35 mm or less.

  Quartz is also a heat insulating material, and the peripheral portion of the susceptor 74 and the base ring 71 are connected by a connecting portion 72 formed of the quartz. For this reason, heat conduction generated between the wall surface of the chamber 6 and the semiconductor wafer W can be suppressed, and the temperature of the semiconductor wafer W can be raised to a constant temperature regardless of the temperature of the wall surface of the chamber 6. As a result, even when processing a plurality of semiconductor wafers W continuously, the temperature history between them can be made uniform.

  Furthermore, in this embodiment, since the connection part 72 is formed with the same material (quartz) as the susceptor 74 and the base ring 71, a temperature difference is not easily generated between them. In addition, since the thermal expansion coefficients of the connecting portion 72, the susceptor 74, and the base ring 71 are the same, the semiconductor wafer W is less likely to be damaged due to temperature changes when the semiconductor wafer W is heated and lowered.

  While the embodiments of the present invention have been described above, the present invention can be modified in various ways other than those described above without departing from the spirit of the present invention. For example, in the above embodiment, the susceptor 74 and the base ring 71 are connected by the four connecting portions 72, but the number of the connecting portions 72 is not limited to four, and the susceptor 74 is stabilized. As long as the number can be supported (for example, three or five).

Further, the material of the connecting portion 72 is not limited to quartz, and other materials may be used. As a material of the connecting portion 72, in order to suppress heat conduction generated between the wall surface of the chamber 6 and the semiconductor wafer W, a heat insulating material having a thermal conductivity of 30 W · m ⁻¹ · K ⁻¹ or less is used. preferable. As such a heat insulating material, in addition to quartz, silicon carbide (SiC) or silicon nitride (SiN) can be used. When the connecting portion 72 is formed of a material other than quartz, it is preferable that the susceptor 74 and the base ring 71 are also formed of the same material as the connecting portion 72 in order to prevent a temperature difference from occurring in the holding portion 7. .

  In the above embodiment, the connecting portion 72, the susceptor 74, and the base ring 71 are fixed by welding. However, the entire holding portion 7 including the base ring 71, the connecting portion 72, and the susceptor 74 is made of quartz. You may make it process from an ingot and integrally form. In other words, any shape may be used as long as it is fixed to the peripheral portion of the susceptor 74 at the L-shaped distal end portion of the connecting portion 72 and to the base ring 71 at the L-shaped proximal end portion.

  Further, a support pin may be erected on the upper surface of the susceptor 74 inside the five guide pins 76, and the semiconductor wafer W may be supported from below by the support pins.

  Moreover, in the said embodiment, although the base ring 71 was made into the annular shape, it does not necessarily need to be a perfect annular shape. That is, the shape of the base ring 71 may be an arc shape in which a part is omitted from the annular shape. However, when the base ring 71 is a completely circular quartz member as in the above embodiment, the connecting portion 72 and the susceptor 74 can be stably supported, and the semiconductor wafer W immediately after flash light irradiation is obtained. It is more effective for suppressing the vibration of the susceptor 74.

  In each of the above embodiments, the flash heating unit 5 is provided with 30 flash lamps FL. However, the present invention is not limited to this, and the number of flash lamps FL may be an arbitrary number. it can. The flash lamp FL is not limited to a xenon flash lamp, and may be a krypton flash lamp. Further, the number of halogen lamps HL provided in the halogen heating unit 4 is not limited to 40, and may be an arbitrary number.

  The substrate to be processed by the heat treatment apparatus according to the present invention is not limited to a semiconductor wafer, and may be a glass substrate or a solar cell substrate used for a flat panel display such as a liquid crystal display device. Further, the technique according to the present invention may be applied to bonding of metal and silicon or crystallization of polysilicon.

DESCRIPTION OF SYMBOLS 1 Heat processing apparatus 2 Shutter mechanism 3 Control part 4 Halogen heating part 5 Flash heating part 6 Chamber 7 Holding part 10 Transfer mechanism 21 Shutter plate 22 Slide drive mechanism 61 Chamber side part 62 Recessed part 63 Upper chamber window 64 Lower chamber window 65 Heat treatment Space 71 Base ring 72 Connecting portion 72a Tip portion 72b Base end portion 74 Susceptor FL Flash lamp HL Halogen lamp W Semiconductor wafer

Claims (6)

A heat treatment apparatus for heating a substrate by irradiating the substrate with flash light,
A chamber for housing the substrate;
A flat plate-shaped susceptor for mounting and holding a substrate in the chamber;
A base supported on the wall of the chamber;
A plurality of connecting members connecting the peripheral portion of the susceptor and the base;
A flash lamp that irradiates flash light onto the substrate held by the susceptor;
A light irradiation means for preheating the substrate held by the susceptor by light irradiation;
With
The cross-section of the connecting member cut at a vertical plane including a straight line connecting the center of the susceptor in a horizontal posture and the peripheral edge portion is L-shaped,
The connecting member is fixed to the peripheral portion of the susceptor at the L-shaped distal end portion and fixed to the base at the L-shaped proximal end portion. . The heat treatment apparatus according to claim 1, wherein
The heat treatment apparatus, wherein the connecting member is formed of a heat insulating material. The heat treatment apparatus according to claim 2,
The heat treatment apparatus, wherein the connecting member is made of quartz. In the heat treatment apparatus according to claim 2 or claim 3,
The heat treatment apparatus, wherein the connecting member is formed of the same material as the susceptor and the base. In the heat processing apparatus in any one of Claims 1-4,
The width of the connecting member along the direction perpendicular to the vertical plane is 3 mm or more and 40 mm or less,
The thickness of the thinnest part of the said connection member is 3 mm or more and 35 mm or less, The heat processing apparatus characterized by the above-mentioned. In the heat processing apparatus in any one of Claims 1-5,
The heat treatment apparatus, wherein the base has an annular shape.

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