JP2010003801A - Heat treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat treatment device capable of preventing a substrate from cracking during the irradiation of flash light from a flash lamp. <P>SOLUTION: A holding plate 74 which holds a semiconductor wafer W is a nearly disk-like member formed of quartz, and has a disk-like recessed portion 78 formed having a smaller diameter than the semiconductor wafer W in plan view. An edge portion of the semiconductor wafer W is supported in linear contact by an edge portion 79 enclosing the recessed portion 78. A gap having a predetermined interval is formed between a reverse surface of the semiconductor wafer W and a bottom surface of the recessed portion 78, and an air layer is sandwiched in the gap. After being irradiated with halogen light from below to be preheated, the semiconductor wafer W held by the holding plate 74 is irradiated with flash light from above to be flash-heated. The air layer suppresses vibrations of the semiconductor wafer W and also prevents heat conduction between the holding plate 74 and semiconductor wafer W. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a heat treatment apparatus for heating a substrate by irradiating a semiconductor wafer, a glass substrate or the like (hereinafter simply referred to as “substrate”) with flash light.

  Conventionally, a lamp annealing apparatus using a halogen lamp has been generally used in an impurity activation process of a semiconductor wafer after impurity implantation. In such a lamp annealing apparatus, the semiconductor wafer is heated (annealed) to a temperature of about 1000 ° C. to 1100 ° C., for example, to activate the impurities of the semiconductor wafer. In such a heat treatment apparatus, the temperature of the substrate is raised at a rate of several hundred degrees per second by using the energy of light irradiated from the halogen lamp.

  On the other hand, in recent years, as semiconductor devices have been highly integrated, it is desired to reduce the junction depth as the gate length becomes shorter. However, even when the impurity activation of the semiconductor wafer is performed using the above-described lamp annealing apparatus that raises the temperature of the semiconductor wafer at a speed of about several hundred degrees per second, impurities such as boron and phosphorus implanted in the semiconductor wafer are heated. It was found that the phenomenon of deep diffusion occurs. When such a phenomenon occurs, there is a concern that the junction depth becomes deeper than required, which hinders good device formation.

  For this reason, only the surface of the semiconductor wafer into which impurities have been implanted is irradiated by flashing the surface of the semiconductor wafer using a xenon flash lamp (hereinafter simply referred to as “flash lamp” means xenon flash lamp). There has been proposed a technique for raising the temperature of the material in an extremely 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. It has also been found that if the flash 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.

  In heat treatment equipment that uses a xenon flash lamp, the semiconductor wafer is irradiated with extremely high energy light instantaneously, so the surface temperature of the semiconductor wafer rises rapidly and abrupt thermal expansion occurs on the wafer surface. The semiconductor wafer was broken with high probability. In order to solve the cracks peculiar to the heat treatment using such a xenon flash lamp, for example, Patent Documents 1 and 2 disclose a technique for forming a taper at the peripheral portion of a wafer pocket of a susceptor holding a semiconductor wafer. .

JP 2004-179510 A JP 2004-247339 A

  By using techniques such as those disclosed in Patent Documents 1 and 2, the semiconductor wafer can be prevented from cracking to some extent when a xenon flash lamp is used, but the type of semiconductor wafer and heat treatment conditions (preliminary) Depending on the heating temperature and irradiation energy, cracks still occurred with considerable frequency.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a heat treatment apparatus that can prevent the substrate from being cracked during flash irradiation from a flash lamp.

  In order to solve the above-mentioned problem, the invention of claim 1 is a heat treatment apparatus for heating a substrate by irradiating flash light on the substrate, a chamber for accommodating the substrate, and the substrate in a horizontal position in the chamber. A holding member for holding; a flash lamp for irradiating the substrate held by the holding member with flash light; and a light irradiation means for preheating the substrate held by the holding member by light irradiation. Is provided with a flat-plate-shaped concave portion smaller than the planar size of the substrate in plan view.

  According to a second aspect of the present invention, in the heat treatment apparatus according to the first aspect of the invention, the substrate has a disk shape, and the concave portion has a disk shape having a smaller diameter than the substrate.

  According to a third aspect of the present invention, in the heat treatment apparatus according to the second aspect of the present invention, the depth of the recess is 1 mm or more and 10 mm or less.

  According to a fourth aspect of the present invention, in the heat treatment apparatus according to the second or third aspect of the present invention, the diameter of the recess is not less than 80% and not more than 99% of the diameter of the substrate.

  According to a fifth aspect of the present invention, there is provided a heat treatment apparatus for heating a substrate by irradiating a flash with the substrate, a chamber for accommodating the substrate, and a holding member for holding the substrate in a horizontal posture in the chamber. A flash lamp for irradiating the substrate held by the holding member with flash light; and a light irradiation means for preheating the substrate held by the holding member by light irradiation, the holding member facing upward. In this case, a truncated cone-shaped concave portion having a wide opening is provided, and the upper bottom surface of the truncated cone shape is larger than the planar size of the substrate, and the lower bottom surface is smaller than the planar size.

  The invention of claim 6 is the heat treatment apparatus according to any one of claims 1 to 5, wherein the holding member is made of quartz, and the light irradiation means emits light from below the chamber. And the flash lamp performs flash irradiation from above the chamber.

  According to a seventh aspect of the present invention, in the heat treatment apparatus according to any one of the first to sixth aspects, the light irradiation means includes a halogen lamp.

  According to the present invention, the gas layer is sandwiched between the holding member and the substrate, and the gas layer acts as a resistance during flash irradiation from the flash lamp to suppress the vibration of the substrate and prevent the substrate from cracking. be able to. Moreover, the heat conduction between the holding member and the substrate can be prevented by the gas layer, and the thermal influence from the holding member can be suppressed to the minimum.

  In particular, according to the invention of claim 2, since the edge portion of the substrate is held by line contact, there is no possibility that the holding portion is worn and the bottom surface of the substrate is prevented from being damaged. The

  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 (flash light) onto a disk-shaped semiconductor wafer W having a diameter of 300 mm as a substrate.

  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 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 recessed portion 62 is formed on the inner wall surface of the chamber 6. That is, a hollow portion 62 is formed that is 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. The The recessed portion 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 indented portion 62. For this reason, 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 transferred from the heat treatment space 65. Can be carried out. 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 recessed portion 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 below the indented portion 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 90. 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. The nitrogen gas supply source 85 and the exhaust unit 90 may be a mechanism provided in the heat treatment apparatus 1 or a utility of a factory where the heat treatment apparatus 1 is installed.

  A gas exhaust pipe 91 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 91 is connected to the exhaust unit 90 via a valve 92. By opening the valve 92, the gas in the chamber 6 is exhausted through the transfer opening 66.

  The holding unit 7 includes a susceptor 70 and a holding plate 74. FIG. 2 is a perspective view of the holding plate 74, and FIG. 3 is a longitudinal sectional view of the holding plate 74. FIG. 4 is a plan view of the entire holding unit 7 including the holding plate 74. The susceptor 70 is made of quartz, and is configured such that a plurality of claw portions 72 (four in this embodiment) are erected on an annular ring portion 71.

  The holding plate 74 is a substantially disk-shaped member made of quartz. The diameter of the holding plate 74 is larger than the diameter of the semiconductor wafer W. The holding plate 74 is formed with a disk-shaped recess (counterbore) 78 having a diameter smaller than that of the semiconductor wafer W in plan view. Since the recess 78 has a flat disk shape, the semiconductor wafer W held by the holding plate 74 and the bottom surface of the recess 78 are parallel to each other.

  The depth t of the recess 78 is not less than 1 mm and not more than 10 mm, and is 3 mm in the present embodiment. Further, the diameter r1 of the disc-shaped recess 78 is 80% or more and 99% or less of the diameter r2 (usually 300 mm or 200 mm) of the circular semiconductor wafer W.

  When the semiconductor wafer W is held by the holding plate 74 having such a concave portion 78, the semiconductor wafer W is larger than the concave portion 78. Therefore, as shown in FIGS. The edge portion 79 of the semiconductor wafer W is supported by line contact by the edge portion 79. As a result, a gap having a predetermined interval is formed between the lower surface of the semiconductor wafer W and the bottom surface of the recess 78, and the gas layer is sandwiched in the gap.

  A plurality of (six in this embodiment) guide pins 76 are provided on the upper surface of the holding plate 74 (upper portion surrounding the recess 78) along a circumference that is concentric with the outer circumference of the holding plate 74. ing. The diameter of the circle formed by the six guide pins 76 is slightly larger than the diameter of the semiconductor wafer W. Each guide pin 76 is made of quartz. Instead of the plurality of guide pins 76, an annular member having a tapered surface that forms a predetermined angle with the horizontal plane may be provided so as to expand upward.

  The susceptor 70 is attached to the chamber 6 by placing the ring portion 71 on the bottom surface of the recessed portion 62. The holding plate 74 is supported by the claw portion 72 of the susceptor 70 attached to the chamber 6. The semiconductor wafer W carried into the chamber 6 is placed in a horizontal posture on the holding plate 74 supported by the susceptor 70.

  FIG. 5 is a view showing the holding plate 74 supported by the susceptor 70. A support rod 73 is erected on each claw portion 72 of the susceptor 70. When the upper end portion of the support rod 73 is fitted into a hole formed in the lower surface of the holding plate 74, the holding plate 74 is supported by the susceptor 70 without being displaced.

  The guide pins 76 are also erected by being fitted into holes formed in the upper surface of the holding plate 74. The upper ends of the guide pins 76 erected on the upper surface of the holding plate 74 protrude from the upper surface, and the height position thereof is higher than the upper surface of the semiconductor wafer W held by the holding plate 74. For this reason, the horizontal displacement of the semiconductor wafer W is prevented by the plurality of guide pins 76. The guide pin 76 may be processed integrally with the holding plate 74.

  As shown in FIGS. 2 and 4, the holding plate 74 has two openings 75. The two openings 75 are for measuring the temperature of the semiconductor wafer W held on the holding plate 74 by a contact thermometer and a radiation thermometer (not shown). The contact-type thermometer includes a thermocouple, and the tip of the thermocouple is brought into contact with the lower surface of the semiconductor wafer W through one opening 75. The radiation thermometer includes an infrared sensor, and measures the intensity (energy amount) of radiated light (infrared light) radiated from the lower surface of the semiconductor wafer W through the other opening 75. The temperature of the wafer W is measured.

  FIG. 6 is a plan view of the transfer mechanism 10. FIG. 7 is a side view of the transfer mechanism 10. The transfer mechanism 10 includes two transfer arms 11. The transfer arm 11 has a circular arc shape along 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 movement mechanism 13 includes a transfer operation position (solid line position in FIG. 6) 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 retreat positions (two-dot chain line positions in FIG. 6) 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 the through holes 77 (see FIGS. 2 and 4) formed in the holding plate 74, The upper end of the lift pin 12 protrudes from the upper surface of the holding plate 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 77, 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 ring portion 71 of the susceptor 70. Since the ring portion 71 is placed on the bottom surface of the recessed portion 62, the retracted position of the transfer arm 11 is inside the recessed portion 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-shaped 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 holding unit 7 (that is, along the horizontal direction). They are arranged in a plane so as to be parallel to each other. 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 flash light emitted from the plurality of flash lamps FL toward the holding unit 7. 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. 8 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.

  In addition, as shown in FIG. 8, the arrangement density of the halogen lamps HL in the region facing the edge portion is higher than the region facing the center portion of the semiconductor wafer W held by the holding portion 7 in both the upper and lower steps. ing. 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 edge 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 has a magnetic disk.

  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. Here, the semiconductor wafer W to be processed is a semiconductor substrate to which an impurity (ion) is added by an ion implantation method, and the activation of the added impurity is performed by a flash heating process by the heat treatment apparatus 1. FIG. 9 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 is executed 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 92 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 92 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. 9.

  Subsequently, the gate valve 185 is opened to open the transfer opening 66, and the semiconductor wafer W after the impurity 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, the pair of transfer arms 11 of the transfer mechanism 10 moves horizontally from the retracted position to the transfer operation position and rises, so that the lift pins 12 protrude from the upper surface of the holding plate 74 through the through holes 77 and the semiconductor wafer. W is received.

  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 holding plate 74 of the holding unit 7 and held in a horizontal posture. The pair of transfer arms 11 lowered to below the holding plate 74 is retracted to the retracted position, that is, inside the indented portion 62 by the horizontal moving mechanism 13.

  Since the diameter r1 of the recess 78 is not less than 80% and not more than 99% of the diameter r2 of the semiconductor wafer W, the edge of the semiconductor wafer W surrounds the recess 78 when the pair of transfer arms 11 are lowered at the transfer operation position. The ring-shaped edge 79 is supported by line contact. Thereby, a gap having a thickness of 3 mm is formed between the lower surface of the semiconductor wafer W and the bottom surface of the recess 78, and the gas layer is sandwiched in the gap.

  After the semiconductor wafer W is placed and held on the holding plate 74 of the holding unit 7, 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 is irradiated from the back surface of the semiconductor wafer W through the lower chamber window 64 and the holding plate 74 formed of quartz. By receiving light from the halogen lamp HL, the semiconductor wafer W is preheated and the temperature rises. In addition, a part of the light in the infrared region among the light emitted from the halogen lamp HL is absorbed by the lower chamber window 64 and the holding plate 74 made of quartz, so that these also rise in temperature slightly. 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 holding unit 7 in plan view, the semiconductor wafer W is irradiated from the halogen lamp HL. The transferred light 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.

  When preheating with the halogen lamp HL is performed, the temperature of the semiconductor wafer W is measured by a contact thermometer. That is, a contact-type thermometer with a built-in thermocouple contacts the lower surface of the semiconductor wafer W held by the holding unit 7 through the opening 75 of the holding plate 74 and measures 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 using a radiation thermometer is not performed. This is because the halogen light emitted from the halogen lamp HL enters the radiation thermometer as disturbance light, and accurate temperature measurement cannot be performed.

  In the present embodiment, the preheating temperature T1 is 800 ° 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 to the holding part 7 in the heat treatment space 65, and another part is once reflected by the reflector 52 and then goes into the heat treatment space 65. The flash heating of the semiconductor wafer W is performed by the irradiation of the flash light. Since the flash heating is performed by flash 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 irradiation from the flash lamp FL instantaneously rises to a processing temperature T2 of about 1000 ° C. to 1100 ° C., and the impurities added to the semiconductor wafer W are activated. After being done, 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. Since the time required for activation of the added impurity is extremely short compared to the time required for thermal diffusion, activation is possible even for a short time when no diffusion of about 0.1 millisecond to 10 millisecond occurs. Is completed. Note that 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 the present embodiment, the semiconductor wafer W is preheated to the preheating temperature T1 (800 ° 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 800 ° C. relatively quickly. Impurity diffusion can be minimized. Further, the surface temperature of the semiconductor wafer W can be rapidly raised to the processing temperature T2 by performing flash irradiation from the flash lamp FL after the temperature of the semiconductor wafer W is raised to the preheating temperature T1. Further, since the temperature increase range by the flash heating from the preheating temperature T1 to the processing temperature T2 is relatively small, the energy of the flash light irradiated from the flash lamp FL can be made relatively small. As a result, the semiconductor wafer W is heated during the flash heating. The thermal shock given to the can be reduced.

  After the flash lamp FL is turned on and 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 with a radiation thermometer is started when the shutter plate 21 is inserted into the light shielding position. That is, the radiation thermometer measures the intensity of the infrared light emitted from the lower surface of the semiconductor wafer W held by the holding unit 7 through the opening 75 of the holding plate 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 a certain amount of radiation continues to be emitted from the high-temperature halogen lamp HL immediately after the light is turned off, the radiation thermometer 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 lamp HL toward the heat treatment space 65 in the chamber 6 is shielded. Therefore, the radiation thermometer can accurately measure the temperature of the semiconductor wafer W held on the holding plate 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 (step S8). 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 again moved horizontally from the retracted position to the transfer operation position and raised, whereby the lift pins 12 are held. The semiconductor wafer W protruding from the upper surface of the plate 74 and receiving the heat treatment is received from the holding plate 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 S9), and the semiconductor wafer in the heat treatment apparatus 1 is transferred. The W flash heat treatment is completed.

  Meanwhile, in the above heat treatment step, the surface temperature of the semiconductor wafer W flash-heated by flash irradiation from the flash lamp FL instantaneously rises to a processing temperature T2 of about 1000 ° C. to 1100 ° C., while the back surface temperature at that moment Does not increase so much from the preheating 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. Act. As a result, the semiconductor wafer W tries to vibrate vigorously on the holding plate 74.

  In the present embodiment, the edge portion of the semiconductor wafer W is supported by line contact by the edge portion 79 surrounding the recess 78, and is substantially closed with a thickness of 3 mm between the lower surface of the semiconductor wafer W and the bottom surface of the recess 78. A gap is formed. As a result, a thin gas layer having a thickness of 3 mm is sandwiched between the inner surface of the lower surface of the semiconductor wafer W and the recess 78. Such a thin gas layer acts as a resistance to vibration of the semiconductor wafer W. That is, since it is difficult for instantaneous gas to enter and exit the thin gas layer between the inner surface of the lower surface of the semiconductor wafer W and the recess 78, volume change in an extremely short time is unlikely to occur, and this is the vibration of the semiconductor wafer W. It becomes resistance of. As a result, even when flash light is emitted from the flash lamp FL, the semiconductor wafer W is hardly moved while being supported by the edge portion 79 of the holding plate 74, and the semiconductor wafer W can be prevented from cracking.

  Note that an opening 75 and a through hole 77 are formed in the recess 78, and the gap between the lower surface of the semiconductor wafer W and the recess 78 is not completely airtight. However, the flash light irradiation time is extremely short, about 0.1 to 10 milliseconds, and it is impossible for a large amount of gas to enter and exit from the opening 75 or the through-hole 77 in such an extremely short time. Therefore, the gas layer can be sufficient for resistance to vibration of the semiconductor wafer W during flash heating.

  Further, since a gas layer having a thickness of 3 mm is sandwiched between the lower surface of the semiconductor wafer W and the recess 78, the temperature of the semiconductor wafer W is not easily affected by the holding plate 74. Since the holding plate 74 is made of quartz, the degree of temperature rise due to the halogen light from the halogen lamp HL in the preheating stage is lower than that of the silicon semiconductor wafer W. For this reason, when a plurality of semiconductor wafers W constituting a lot are continuously processed, if the gas layer does not exist, heat is conducted to the holding plate 74, particularly for the first semiconductor wafer W to be processed. It takes a long time to raise the temperature to the heating temperature T1. On the contrary, the second and subsequent semiconductor wafers W in the lot are affected by the heat from the holding plate 74 that has already been heated to some extent, so that the temperature rising time to the preheating temperature T1 is shortened. Therefore, the temperature history between the semiconductor wafers W varies within one lot.

  In the present embodiment, since a gas layer having a thickness of 3 mm is sandwiched between the lower surface of the semiconductor wafer W and the recess 78, heat conduction between the semiconductor wafer W and the holding plate 74 is unlikely to occur. Variations in temperature history as described above among a plurality of semiconductor wafers W to be processed can be suppressed.

  If the depth t of the concave portion 78 is less than 1 mm, the semiconductor wafer W is held close to the bottom surface of the concave portion 78, so that heat conduction is likely to occur between the semiconductor wafer W and the holding plate 74. As a result, variations in temperature history occur between a plurality of semiconductor wafers W to be processed continuously. For this reason, the depth t of the recess 78 needs to be 1 mm or more, and is preferably 3 mm or more in order to more effectively prevent heat conduction between the semiconductor wafer W and the holding plate 74.

  On the other hand, when the depth t of the concave portion 78 exceeds 10 mm, the gas layer formed between the lower surface inner portion of the semiconductor wafer W and the concave portion 78 becomes thick and the volume change thereof is relatively easy. Cannot become resistance to vibration of the semiconductor wafer W during flash heating. For this reason, the depth t of the recessed part 78 needs to be 10 mm or less, and in order to suppress more effectively the vibration of the semiconductor wafer W at the time of flash heating, it is preferable to set it to 5 mm or less. Therefore, the depth t of the recessed part 78 is 1 mm or more and 10 mm or less, and desirably 3 mm or more and 5 mm or less.

  Further, in order to reduce the heat conduction between the semiconductor wafer W and the holding plate 74 and suppress the variation of the temperature history between the semiconductor wafers W, the contact area between the edge portion 79 and the semiconductor wafer W is as much as possible. The diameter r1 of the recess 78 is preferably at least 80% of the diameter r2 of the semiconductor wafer W. For this reason, the diameter r1 of the recess 78 is 80% or more and 99% or less of the diameter r2 of the semiconductor wafer W. The reason why the diameter r1 of the recess 78 is 99% or less of the diameter r2 of the semiconductor wafer W is to hold the semiconductor wafer W by the edge portion 79 reliably.

  In this embodiment, since the edge of the semiconductor wafer W is supported by line contact by the annular edge 79 surrounding the recess 78 of the holding plate 74, the semiconductor wafer is point contacted by pins or the like. Compared to supporting W, the contact area becomes wider, and the load per unit area at the contact portion with the edge portion 79 becomes smaller. For this reason, even if the semiconductor wafer W moves slightly during flash heating, the edge portion 79 of the holding plate 74 is not likely to be worn, and the lower surface edge portion of the semiconductor wafer W is not likely to be damaged.

  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 disk-shaped recess 78 having a diameter smaller than the diameter of the semiconductor wafer W in plan view is formed in the holding plate 74, but the shape of the recess 78 is limited to the disk shape. Is not to be done. The shape of the concave portion 78 may be, for example, a polygonal plate shape. If the planar shape is smaller than the planar size of the semiconductor wafer W in a plan view, a substantially closed gap is formed between the semiconductor wafer W and the concave portion. The gas layer can be sandwiched and formed, and the same effect as the above embodiment can be obtained. However, the planar shape of the concave portion 78 is preferably similar to the planar shape of the substrate to be processed, and a disk-shaped concave portion 78 is preferable for the circular semiconductor wafer W.

  Further, the holding plate 74 may be provided with a recess 178 as shown in FIG. The holding plate 74 is formed with a truncated cone-shaped recess 178 whose opening becomes wider upward. The upper bottom surface of the truncated cone shape (the opening surface of the recess 178) is larger than the planar size of the semiconductor wafer W, and the lower bottom surface (the bottom surface 178a of the recess 178) is smaller than the planar size of the semiconductor wafer W. Therefore, when the semiconductor wafer W is held by the holding plate 74 in which the concave portion 178 is formed, the edge portion of the semiconductor wafer W is supported by the tapered surface 178b of the concave portion 178 as shown in FIG. As a result, a gap is formed between the lower surface of the semiconductor wafer W and the upper surface of the holding plate 74, and the gas layer is sandwiched.

  Even when the semiconductor wafer W is held by the holding plate 74 having the recess 178 as shown in FIG. 10 and flash heating is performed, a gas layer is formed between the lower surface of the semiconductor wafer W and the bottom surface 178a of the recess 178. Since it is sandwiched, vibrations of the semiconductor wafer W during flash heating can be suppressed, and heat conduction between the semiconductor wafer W and the holding plate 74 can be prevented, and the temperature history between the plurality of semiconductor wafers W can be reduced. Variations can be suppressed.

  In the above embodiment, when the temperature of the semiconductor wafer W reaches the preheating temperature T1, the flash lamp FL is irradiated while the halogen lamp HL is turned on. As soon as the temperature reaches the preheating temperature T1, the halogen lamp HL is turned off, and the shutter plate 21 is inserted into the light shielding position to irradiate the flash light from the flash lamp FL. Further, after the temperature of the semiconductor wafer W is raised by the halogen lamp HL beyond the preheating temperature T1, the halogen lamp HL is turned off and the shutter plate 21 is inserted into the light shielding position, and the temperature of the semiconductor wafer W is lowered to the preheating temperature T1. You may make it perform flash irradiation at the time of doing.

  In the above embodiment, 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 can be any number. . 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 used for a liquid crystal display device or the like. If the substrate to be processed is a rectangular glass substrate, it is preferable that the recess 78 has a rectangular plate shape similar to the glass substrate.

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 of a holding plate. It is a longitudinal cross-sectional view of a holding plate. It is a top view of the whole holding part containing a holding plate. It is a figure which shows the holding | maintenance plate supported by a susceptor. 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. It is a longitudinal cross-sectional view which shows the other example of a holding plate.

Explanation of symbols

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 70 Susceptor 71 Ring part 72 Claw part 74 Holding plate 75 Opening part 78,178 Concave part 79 Edge part FL Flash lamp HL Halogen lamp W Semiconductor wafer

Claims (7)

A heat treatment apparatus for heating a substrate by irradiating a flash with the substrate,
A chamber for housing the substrate;
A holding member for holding the substrate in a horizontal position in the chamber;
A flash lamp for irradiating a flash on the substrate held by the holding member;
A light irradiation means for preheating the substrate held by the holding member by light irradiation;
With
The heat treatment apparatus, wherein the holding member includes a flat plate-like recess that is smaller than a planar size of the substrate in a plan view. The heat treatment apparatus according to claim 1, wherein
The substrate has a disc shape;
The heat treatment apparatus characterized in that the recess has a disk shape having a smaller diameter than the substrate. The heat treatment apparatus according to claim 2,
The depth of the said recessed part is 1 mm or more and 10 mm or less, The heat processing apparatus characterized by the above-mentioned. In the heat treatment apparatus according to claim 2 or claim 3,
The diameter of the recess is 80% to 99% of the diameter of the substrate. A heat treatment apparatus for heating a substrate by irradiating a flash with the substrate,
A chamber for housing the substrate;
A holding member for holding the substrate in a horizontal position in the chamber;
A flash lamp for irradiating a flash on the substrate held by the holding member;
A light irradiation means for preheating the substrate held by the holding member by light irradiation;
With
The holding member includes a truncated cone-shaped recess having an opening that widens upward, and the upper bottom surface of the truncated cone shape is larger than the planar size of the substrate, and the lower bottom surface is smaller than the planar size. Heat treatment equipment. In the heat processing apparatus in any one of Claims 1-5,
The holding member is made of quartz,
The light irradiation means performs light irradiation from below the chamber,
A heat treatment apparatus, wherein the flash lamp performs flash irradiation from above the chamber. In the heat processing apparatus in any one of Claims 1-6,
The light irradiation means includes a halogen lamp.

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