JP5964630B2 - Heat treatment equipment - Google Patents

Description

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

  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 Document 1, a flash lamp is arranged on the front surface side of a semiconductor wafer and a halogen lamp is arranged on the back surface side, and a desired heat treatment is performed by a combination thereof. Is disclosed. In the heat treatment apparatus disclosed in Patent Document 1, a semiconductor wafer held on a susceptor is preheated to a certain temperature by a halogen lamp, and then heated to a desired processing temperature by flash light irradiation from the flash lamp. Yes.

JP 2009-164451 A

  In the heat treatment apparatus disclosed in Patent Document 1, a quartz plate that holds a semiconductor wafer during flash light irradiation is provided. The quartz plate has an opening for measuring the temperature of the semiconductor wafer with a radiation thermometer. Immediately above the opening, the temperature of the semiconductor wafer during preheating is lower than in other regions. Also, during preheating with a halogen lamp, the temperature of the semiconductor wafer is likely to decrease. As a result, there has been a problem that the in-plane distribution of the semiconductor wafer at the time of flash light irradiation is also non-uniform.

  This invention is made | formed in view of the said subject, and it aims at providing the heat processing apparatus which can heat a board | substrate uniformly.

In order to solve the above-mentioned problems, a first aspect of the present invention provides a heat treatment apparatus for heating a substrate by irradiating the substrate with flash light, a chamber for accommodating the substrate, and a holding means for holding the substrate in the chamber. A flash lamp that irradiates flash light to one surface of the substrate held by the holding means, a halogen lamp that irradiates light to the other surface of the substrate held by the holding means, and light irradiation from the halogen lamp Temperature measuring means for measuring the temperature of the substrate heated by the substrate, wherein the holding means includes a plurality of supporting members that are supported from the outer peripheral end side of the substrate, and the plurality of supporting members include silicon carbide and aluminum nitride. , coated graphite with silicon carbide, or formed by silicon nitride, wherein each of the plurality of support members, the center from the outside of the substrate A first support that is inclined obliquely downward, and a second support that is provided so as to extend in a horizontal direction from a front end of the first support and that contacts the lower surface of the substrate. 2 The support is provided with a protrusion that makes point contact with the lower surface of the substrate .

The invention according to claim 2 is the heat treatment apparatus according to claim 1, further comprising an annular member that is placed on the second support and surrounds the periphery of the substrate in a non-contact manner, and the annular member is carbonized. It is characterized by being formed of silicon, aluminum nitride, graphite coated with silicon carbide, or silicon nitride.

According to a third aspect of the present invention, in the heat treatment apparatus according to the first or second aspect of the present invention, the plurality of support members are fixed to a quartz ring having an inner diameter larger than the diameter of the substrate. And

According to a fourth aspect of the present invention, in the heat treatment apparatus according to the third aspect of the present invention, the quartz ring is fixedly installed in the chamber.

The invention according to claim 5 is the heat treatment apparatus according to any one of claims 1 to 4 , further comprising pressure maintaining means for maintaining the inside of the chamber at a pressure of 50 Pa or more and 500 Pa or less. To do.

The invention of claim 6 is the heat treatment apparatus according to the invention of claim 5 , wherein the pressure maintaining means is an exhaust means for exhausting the atmosphere in the chamber, and a gas supply for supplying an inert gas into the chamber. And an inert gas is supplied into the chamber while the chamber is evacuated to maintain the inside of the chamber at a pressure of 50 Pa to 500 Pa.

According to the first to sixth aspects of the present invention, the holding means includes a plurality of support members supported from the outer peripheral end side of the substrate, and the plurality of support members are coated with silicon carbide, aluminum nitride, or silicon carbide. Alternatively, since it is formed of silicon nitride, it is possible to minimize the disturbance of the temperature distribution of the substrate by the support member, and the substrate can be heated uniformly. Further, since the lower part of the substrate is opened, the temperature measurement of the substrate by the temperature measuring means becomes easy.

In particular, according to the second aspect of the invention, since the annular member surrounding the periphery of the substrate in a non-contact manner is provided, the temperature of the peripheral portion of the substrate can be prevented from being lowered and the substrate can be heated more uniformly.

In particular, according to the invention of claim 5 , since the pressure maintaining means for maintaining the pressure in the chamber at 50 Pa or more and 500 Pa or less is provided, heat convection does not occur in the chamber, and particularly at the outer edge of the substrate due to convection. The substrate can be heated more uniformly by preventing temperature drop.

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 an external appearance perspective view of the supporting member of 1st Embodiment. It is a figure which shows typically the state by which the semiconductor wafer was hold | maintained by the holding part in 1st Embodiment. 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 an external appearance perspective view of the support member of 2nd Embodiment. It is a figure which shows typically the state by which the semiconductor wafer was hold | maintained by the holding part in 2nd Embodiment. It is a perspective view of the supporting member and soaking ring of a 3rd embodiment. It is a perspective view which shows the other example of a supporting member. It is a perspective view which shows the other example of a supporting member.

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

<First Embodiment>
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. In FIG. 1 and the subsequent drawings, the size and number of each part are exaggerated or simplified as necessary for easy understanding.

  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.

  An O-ring (not shown) is sandwiched between each of the upper chamber window 63 and the lower chamber window 64 and the chamber side portion 61. When the gate valve 185 closes the transfer opening 66, an O-ring is also sandwiched between them. For this reason, when the gate valve 185 closes the transfer opening 66, the heat treatment space 65 in the chamber 6 is sealed to the outside of the apparatus, and the heat treatment space 65 is pressurized to atmospheric pressure or reduced to a vacuum atmosphere. It becomes possible to do.

Further, a gas supply hole 81 for supplying an inert 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. The exhaust unit 190 includes, for example, a dry pump and a throttle valve. A valve 89 is inserted in the middle of the path of the gas exhaust pipe 88. When the dry pump of the exhaust unit 190 is operated while 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. The exhaust flow rate is adjusted by the throttle valve of the exhaust unit 190. 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.

  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. The holding unit 7 includes a base ring 71, a support ring 72, and a plurality of support members 75. The support ring 72 is an annular plate member formed of quartz, and the inner diameter thereof is larger than the diameter (φ300 mm) of the semiconductor wafer W. The base ring 71 is an annular member made of quartz and having the same shape as the support ring 72. The base ring 71 and the support ring 72 are connected by a plurality (three in this embodiment) of connecting members 73. For example, a quartz prism can be used as the connecting member 73. The base ring 71 and the support ring 72 are connected to each other so that their central axes coincide with each other.

  A plurality of support members 75 are fixed on the inner periphery of the support ring 72. The number of support members 75 provided on the support ring 72 is 3 or more and 12 or less. In the first embodiment, three support members 75 are provided along the inner periphery of the support ring 72 at intervals of 120 °. FIG. 3 is an external perspective view of the support member 75. The support member 75 of the first embodiment is a cylindrical member formed of silicon carbide (SiC). Sintered SiC can be used for the support member 75.

  FIG. 4 is a diagram schematically showing a state in which the semiconductor wafer W is held by the holding unit 7. The base ring 71 is fixedly attached to the bottom surface of the recess 62, thereby being fixed to the wall surface of the chamber 6 (see FIG. 1). As a method for fixing the base ring 71 to the chamber 6, for example, the base ring 71 may be fixed to the bottom surface of the recess 62 with a pin. When the base ring 71 is fixedly attached to the chamber 6, the entire holding unit 7 including the support ring 72 and the three support members 75 is fixedly installed in the chamber 6.

  Each of the plurality of support members 75 is provided on the support ring 72 so that the axial direction of the cylinder is inclined obliquely downward from the outside of the semiconductor wafer W to be held toward the center. The angle α formed by each of the plurality of support members 75 with respect to the horizontal plane is 15 ° or more and 30 ° or less. That is, each support member 75 is provided with an inclination of 15 ° or more and 30 ° or less with respect to the horizontal plane. As shown in FIG. 4, three outer peripheral ends of the semiconductor wafer W are supported by the peripheral surfaces of the three support members 75 provided on the support ring 72. That is, each of the three support members 75 provided in an inclined manner contacts the outer peripheral end of the semiconductor wafer W, and the three support members 75 hold the semiconductor wafer W in a horizontal posture from the outer peripheral end side (the normal line is in the vertical direction). Is supported at three points. The height position of the semiconductor wafer W supported by the three support members 75 is slightly lower than the support ring 72.

  The chamber 6 is provided with a radiation thermometer 120. The radiation thermometer 120 can measure the wafer temperature by receiving the radiated light (infrared light) emitted from the lower surface of the semiconductor wafer W supported by the three support members 75. Since the semiconductor wafer W is supported from the outer peripheral end side by the three support members 75 and the inner side of the annular base ring 71 is open, the radiation thermometer 120 emits radiation radiated from the lower surface of the semiconductor wafer W. Light can be reliably received.

  FIG. 5 is a plan view of the transfer mechanism 10. FIG. 6 is a side view of the transfer mechanism 10. The transfer mechanism 10 includes two transfer arms 11. The transfer 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 movement mechanism 13 includes a transfer operation position (a position indicated by a solid line in FIG. 5) 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. 5) 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 inner space of the holding portion 7, and the upper end of the lift pins 12 is higher than the upper surface of the support ring 72. Reach up. On the other hand, the elevating mechanism 14 lowers the pair of transfer arms 11 at the transfer operation position to move the lift pins 12 below the base ring 71 so that the horizontal movement mechanism 13 opens the pair of transfer arms 11. When moved, each transfer arm 11 moves to the retracted position. 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 100 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.

  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. 7 is a plan view showing the arrangement of the 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 and lower stages is a horizontal plane.

  Further, as shown in FIG. 7, 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 holding portion 7 in both the upper stage and the lower stage. Yes. 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 at a light shielding position between the halogen heating unit 4 and the heat treatment space 65. 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. As a result, light traveling from the plurality of halogen lamps HL toward 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. 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. Here, the semiconductor wafer W to be processed is a silicon semiconductor substrate to which impurities (ions) are added by an ion implantation method. The activation of the impurities is performed by flash light irradiation heat treatment (annealing) by the heat treatment apparatus 1. FIG. 8 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 gate valve 185 is opened to open the transfer opening 66, and the semiconductor wafer W after 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 S1). When the transfer opening 66 is opened for wafer loading, an air supply valve 84 is opened to supply an inert gas such as nitrogen gas from the gas supply hole 81 to the heat treatment space 65, and the outside air containing particles is heat treated. You may make it prevent flowing into the space 65.

  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, whereby the lift pins 12 pass through the inner space of the holding unit 7 and receive the semiconductor wafer W.

  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. Then, when the pair of transfer arms 11 are lowered, the semiconductor wafer W is transferred from the transfer mechanism 10 to the three support members 75 of the holding unit 7 (step S2). As shown in FIG. 4, the three support members 75 support the received semiconductor wafer W at three points in a horizontal posture at the outer peripheral end. The semiconductor wafer W is held by the holding unit 7 with the surface on which the pattern is formed and impurities are implanted as the upper surface. The pair of transfer arms 11 lowered to the lower part of the holding unit 7 is retracted to the retracted position by the horizontal moving mechanism 13.

  After the transfer opening 66 is closed and the semiconductor wafer W is held by the holding unit 7, the inside of the chamber 6 is depressurized (step S3). The transfer opening 66 is closed by the gate valve 185, whereby the heat treatment space 65 is a sealed space. In this state, when the valve 89 is opened while operating the dry pump of the exhaust unit 190, the gas in the heat treatment space 65 is exhausted from the gas exhaust hole 86, and the pressure in the chamber 6 is reduced to a low vacuum state of less than 100 Pa.

  Subsequently, an inert gas is supplied into the chamber 6 while exhausting by the exhaust unit 190 (step S4). In the present embodiment, the valve 84 is opened, and nitrogen gas is supplied from the gas supply hole 81 into the chamber 6 that is in a low vacuum state by being exhausted by the exhaust unit 190. At this time, while supplying nitrogen gas at a constant flow rate to the heat treatment space 65 in the chamber 6, the exhaust flow rate is adjusted according to the degree of opening and closing of the throttle valve of the exhaust unit 190, so that the inside of the chamber 6 is 50 Pa to 500 Pa Maintain a low vacuum state. In the present embodiment, the inside of the chamber 6 is maintained at about 100 Pa.

  After the interior of the chamber 6 reaches a predetermined target atmospheric pressure (100 Pa) and stabilizes, the 40 halogen lamps HL of the halogen heating unit 4 are turned on all at once and preheating (assist heating) is started (step S5). . The halogen light emitted from the halogen lamp HL passes through the lower chamber window 64 made of quartz and is irradiated from the back surface of the semiconductor wafer W (the main surface on which the pattern opposite to the front surface is not formed). The By receiving light from the halogen lamp HL, the semiconductor wafer W is preheated and the temperature rises. Since the transfer arm 11 of the transfer mechanism 10 is retracted to the retracted position, and the transfer arm 11 and the lift pin 12 are also formed of transparent quartz, they become obstacles to heating by the halogen lamp HL. There is no.

  When preheating with the halogen lamp HL is performed, the temperature of the semiconductor wafer W is measured by a temperature sensor. As this temperature sensor, for example, a radiation thermometer 120 (see FIG. 4) can be used. In this embodiment, since the lower part of the semiconductor wafer W held by the holding unit 7 is widely opened, the radiation thermometer 120 reliably receives the radiated light emitted from the lower surface of the semiconductor wafer W and is accurate. Temperature measurement can be performed. Further, a contact thermometer using a thermocouple may be used as the temperature sensor. The temperature of the semiconductor wafer W measured by the temperature sensor is transmitted to the control unit 3.

  The controller 3 controls the output of the halogen lamp HL while monitoring 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. That is, the control unit 3 feedback-controls the output of the halogen lamp HL so that the temperature of the semiconductor wafer W becomes the preheating temperature T1 based on the measurement value by the temperature sensor. The preheating temperature T1 is set to about 200 ° C. to 800 ° C., preferably about 350 ° C. to 600 ° C. (in this embodiment, 600 ° C.) at which impurities added to the semiconductor wafer W are not likely to diffuse due to heat. .

  After the temperature of the semiconductor wafer W reaches the preheating temperature T1, the control unit 3 maintains the semiconductor wafer W at the preheating temperature T1 for a while. Specifically, when the temperature of the semiconductor wafer W measured by the temperature sensor reaches the preheating temperature T1, the control unit 3 controls the output of the halogen lamp HL so that the temperature of the semiconductor wafer W is substantially equal to the preheating temperature. It is maintained at T1.

  Next, when a predetermined time elapses after the temperature of the semiconductor wafer W reaches the preheating temperature T1, flash light is irradiated onto the surface of the semiconductor wafer W from the flash lamp FL of the flash heating unit 5 (step S6). . At this time, a part of the flash light emitted from the flash lamp FL goes directly into the chamber 6, and the other part is once reflected by the reflector 52 and then goes into the chamber 6. Flash heating of the semiconductor wafer W is performed by irradiation. In the first embodiment, flash light is emitted from the flash lamp FL in a state where the three support members 75 of the holding unit 7 support the semiconductor wafer W at three points.

  Since the flash heating is performed by irradiation with flash light (flash light) 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 emitted from the flash lamp FL is a very short and strong flash light whose irradiation time is about 0.1 milliseconds or more and 100 milliseconds or less, in which the electrostatic energy stored in advance is converted into an extremely short light pulse. It is. Then, the surface temperature of the semiconductor wafer W that is flash-heated by flash light irradiation from the flash lamp FL instantaneously rises to a processing temperature T2 of 1000 ° C. or more, and the impurities injected into the semiconductor wafer W are activated. Later, 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 the impurities injected into the semiconductor wafer W due to heat. Can do. Moreover, since the surface of the semiconductor wafer W is heated to the processing temperature T2 in a low vacuum state of 100 Pa, oxidation of the surface at the molecular level can also be prevented. Since the time required for the activation of impurities is extremely short compared to the time required for the thermal diffusion, the activation is possible even in a short time in which diffusion of about 0.1 millisecond to 100 millisecond does not occur. Complete.

  After the end of the flash heating process, the halogen lamp HL is turned off after a lapse of a predetermined time (step S7). 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 S8). 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. Note that the temperature of the semiconductor wafer W during the temperature decrease is also measured by the radiation thermometer 120, and the measurement result is transmitted to the control unit 3. Further, together with the temperature drop of the semiconductor wafer W, the valve 89 is closed to stop the exhaust, and the supply of nitrogen gas to the heat treatment space 65 is continued to restore the pressure in the chamber 6 (step S9).

  The controller 3 monitors whether or not the temperature of the semiconductor wafer W measured by the radiation thermometer 120 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 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 after the heat treatment passing through the inner space of the part 7 is received from the three support members 75. 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, and the heat treatment of the semiconductor wafer W in the heat treatment apparatus 1 is performed. Is completed (step S10).

  In the first embodiment, halogen light is irradiated from the halogen lamp HL while the outer peripheral end of the semiconductor wafer W is supported by three cylindrical support members 75 formed of silicon carbide. Preheating is performed. The support member 75 in direct contact with the semiconductor wafer W is silicon carbide that absorbs halogen light better than quartz. Therefore, at the time of preheating, the temperature of the three support members 75 is raised together with the semiconductor wafer W, and a local temperature drop of the semiconductor wafer W due to heat conduction to the support member 75 can be prevented.

  Further, the three support members 75 provided in an inclined manner support the outer peripheral end of the semiconductor wafer W by point contact, and the contact between the holding unit 7 and the semiconductor wafer W is minimized. . For this reason, it is possible to suppress the temperature distribution of the semiconductor wafer W from being disturbed by the support member 75 to the minimum, and the semiconductor wafer W can be uniformly heated.

  Further, the support member 75 is provided so as to be inclined obliquely downward from the outside of the semiconductor wafer W to be held toward the center. For this reason, the side slip of the semiconductor wafer W during the heat treatment can be prevented.

  In the first embodiment, since the heat treatment of the semiconductor wafer W is performed while maintaining the heat treatment space 65 in the chamber 6 in a low vacuum state of 50 Pa or more and 500 Pa or less, convection does not occur on the upper surface of the semiconductor wafer W. . For this reason, it is possible to prevent a temperature drop caused by the relatively low temperature atmospheric gas hitting the peripheral edge of the semiconductor wafer W by convection, and the semiconductor wafer W can be heated more uniformly.

  Further, the three support members 75 support the semiconductor wafer W from the outer peripheral end side, and the inner side of the annular base ring 71 is open, so that the radiation thermometer 120 is radiated from the lower surface of the semiconductor wafer W. Therefore, accurate temperature measurement can be performed by reliably receiving the emitted light.

Second Embodiment
Next, a second embodiment of the present invention will be described. The overall configuration of the heat treatment apparatus of the second embodiment is the same as that of the first embodiment. The processing procedure for the semiconductor wafer W in the second embodiment is the same as that in the first embodiment. The second embodiment is different from the first embodiment in the shape of the support member 75 of the holding unit 7.

  FIG. 9 is an external perspective view of the support member 175 of the second embodiment. The support member 175 of the second embodiment is configured by providing a second support 177 extending in the horizontal direction at the tip of a first support 176 that is inclined obliquely downward. Both the first support 176 and the second support 177 are strip-shaped quadrangular prism-shaped members made of silicon carbide.

  FIG. 10 is a diagram schematically showing a state in which the semiconductor wafer W is held by the holding unit 7 in the second embodiment. As in the first embodiment, the quartz support ring 72 is connected to the base ring 71 via a connecting member 73. When the base ring 71 is fixedly attached to the bottom surface of the recess 62, the entire holding portion 7 is fixedly installed in the chamber 6.

  As in the first embodiment, a plurality of support members 175 are fixed to the inner periphery of the support ring 72. The number of support members 175 provided on the support ring 72 is 3 or more and 12 or less. In the second embodiment, three support members 175 are provided at 120 ° intervals along the inner periphery of the support ring 72. For each of the plurality of support members 175, the first support 176 is provided on the support ring 72 so that the axial direction of the quadrangular column is inclined obliquely downward from the outside of the semiconductor wafer W to be held toward the center. The first support 176 is provided with an inclination of 15 ° or more and 30 ° or less with respect to the horizontal plane. The second support 177 is provided such that the axial direction of the quadrangular prism extends along the horizontal direction from the tip of the first support 176.

  As shown in FIG. 10, in the second embodiment, the second support 177 of the three support members 175 contacts the lower surface of the peripheral edge of the semiconductor wafer W to support the semiconductor wafer W. That is, each of the second supports 177 extending along the horizontal direction contacts the lower surface of the peripheral edge of the semiconductor wafer W to support the semiconductor wafer W in a horizontal posture from the outer peripheral end side. The second support 177 may extend from the outer peripheral end of the φ300 mm semiconductor wafer W to the center side by about 100 mm. The height position of the semiconductor wafer W supported by the three support members 175 is slightly lower than the support ring 72.

  Similarly to the first embodiment, the semiconductor wafer W is supported from the outer peripheral end side by the three support members 175, and the inner side of the annular base ring 71 is open. Accurate temperature measurement can be performed by reliably receiving the radiation emitted from the lower surface of the semiconductor wafer W.

  Also in the second embodiment, the semiconductor wafer W is irradiated with halogen light from the halogen lamp HL in a state where the semiconductor wafer W is supported from the outer peripheral end side by the three support members 175 formed of silicon carbide, and the semiconductor wafer W is preheated. I do. For this reason, the local temperature fall of the semiconductor wafer W resulting from the support member 175 can be prevented, and the semiconductor wafer W can be heated uniformly.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. The overall configuration of the heat treatment apparatus of the third embodiment is the same as that of the first embodiment. The processing procedure for the semiconductor wafer W in the third embodiment is the same as that in the first embodiment. In the third embodiment, the holding unit 7 includes a heat equalizing ring that surrounds the periphery of the semiconductor wafer W.

  FIG. 11 is a perspective view of a support member and a soaking ring according to the third embodiment. The support member 175 of the third embodiment is the same as that of the second embodiment. Similar to the second embodiment, three support members 175 are fixed to the inner periphery of the support ring 72 (not shown in FIG. 11). In the third embodiment, a soaking ring 278 is provided on the upper surface of the second support 177 of the three support members 175. The soaking ring 278 is an annular plate-like member, and its inner diameter is slightly larger than the diameter of the semiconductor wafer W. The soaking ring 278 is made of silicon carbide.

  As shown in FIG. 11, also in the third embodiment, each of the second supports 177 extending along the horizontal direction contacts the lower surface of the peripheral edge of the semiconductor wafer W to bring the semiconductor wafer W into a horizontal posture from the outer peripheral end side. To support. The periphery of the semiconductor wafer W supported by the second support 177 is surrounded by the heat equalizing ring 278 in a non-contact manner. The height position of the semiconductor wafer W supported by the second support 177 is substantially the same as that of the soaking ring 278.

  Also in the third embodiment, the semiconductor wafer W is irradiated with halogen light from the halogen lamp HL while the semiconductor wafer W is supported from the outer peripheral end side by the three support members 175 formed of silicon carbide, and the semiconductor wafer W is preheated. I do. For this reason, the local temperature fall of the semiconductor wafer W resulting from the support member 175 can be prevented, and the semiconductor wafer W can be heated uniformly.

  Furthermore, in the third embodiment, the periphery of the semiconductor wafer W is surrounded in a non-contact manner by the heat equalizing ring 278 formed of silicon carbide as with the support member 175. The soaking ring 278 absorbs halogen light from the halogen lamp HL and raises the temperature to the same level as the support member 175. By surrounding the periphery of the semiconductor wafer W with the heated temperature equalizing ring 278, even if thermal convection is generated in the chamber 6, the convection is prevented from hitting the peripheral edge of the semiconductor wafer W. A temperature drop can be prevented. As a result, the semiconductor wafer W can be heated more uniformly.

<Modification>
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, the support member 75 of the first embodiment has a cylindrical shape, but may have a shape as shown in FIG. The support member 75 in FIG. 12A has a quadrangular prism shape. The support member 75 in FIG. 12B has a rectangular quadrangular prism shape. In any case, the support member 75 is provided on the support ring 72 so that the axial direction of the quadrangular prism is inclined obliquely downward from the outside of the semiconductor wafer W to be held toward the center. The angle formed by the support member 75 with respect to the horizontal plane is 15 ° or more and 30 ° or less. The support member 75 provided in an inclined manner contacts the outer peripheral end of the semiconductor wafer W to support the semiconductor wafer W.

  Further, the supporting member 75 in FIG. 12C is a member in which a protrusion 79 is provided at the tip of the strip-shaped square column in FIG. Similarly to the above, the support member 75 is provided on the support ring 72 so that the axial direction of the quadrangular prism is inclined obliquely downward from the outside of the semiconductor wafer W to be held toward the center. In the support member 75 of FIG. 12C, the protrusion 79 abuts on the lower surface of the peripheral edge of the semiconductor wafer W to support the semiconductor wafer W.

  Further, the support member 175 of the second embodiment may have a shape as shown in FIG. The support member 175 of FIG. 13 is provided with a protrusion 179 at the tip of the support member 175 similar to that of the second embodiment, that is, the tip of the second support 177. The support member 175 of FIG. 13 supports the semiconductor wafer W when the protrusion 179 contacts the lower surface of the peripheral edge of the semiconductor wafer W.

  Both the supporting members 75 and 175 of FIGS. 12 and 13 support the semiconductor wafer W from the outer peripheral end side. By irradiating the halogen light from the halogen lamp HL while the semiconductor wafer W is supported by the support members 75 and 175 from the outer peripheral end side, the local temperature drop of the semiconductor wafer W is prevented and the semiconductor wafer W is prevented. Can be heated uniformly. Further, by supporting the semiconductor wafer W by the protrusions 79 and 179, the local temperature drop of the semiconductor wafer W can be more reliably prevented. Furthermore, the strip-shaped square pillar-shaped support ring 75 is excellent in strength in the thickness direction.

  Further, the support member 75 of the first embodiment and the support member 175 of the second embodiment are formed of silicon carbide, but are not limited to this, and are covered with aluminum nitride (AlN) or silicon carbide. Alternatively, it may be formed of graphite or silicon nitride (SiN). Aluminum nitride can be white or black. Graphite coated with silicon carbide can be made by CVD-SiC coating. All of these absorb halogen light better than quartz. Accordingly, when the halogen light is irradiated from the halogen lamp HL, the support members 75 and 175 are also heated together with the semiconductor wafer W, and a local temperature drop of the semiconductor wafer W can be prevented.

  The material of the soaking ring 278 of the third embodiment is not limited to silicon carbide, but may be formed of black aluminum nitride, graphite coated with silicon carbide, or silicon nitride. .

  Further, the height position of the semiconductor wafer W supported by the support members 75 and 175 may be the same as that of the support ring 72. However, the radiation thermometer 120 is radiated from the lower surface of the semiconductor wafer W when the height position of the semiconductor wafer W supported by the support members 75 and 175 is slightly lower than the support ring 72 as in the above embodiments. Radiation light can be received more reliably.

  Moreover, in each said embodiment, although the support ring 72 and the base ring 71 were connected with the connection member 73, the base ring 71 is not necessarily required. That is, the holding member 7 including the support ring 72 may be fixedly installed in the chamber 6 by fixing the connecting member 73 directly to the inner wall of the chamber 6.

  Further, the inert gas supplied into the chamber 6 from the gas supply hole 81 while exhausting by the exhaust unit 190 is not limited to nitrogen gas, but is argon gas (Ar) or helium gas (He). Also good.

  Further, in each of the above embodiments, the semiconductor wafer W is held with the surface on which the pattern is formed and the impurity is implanted as the upper surface. However, the semiconductor wafer W is held in the opposite direction, that is, with the surface as the lower surface. You may make it hold | maintain. In this case, flash light is irradiated to the back surface of the semiconductor wafer W on which no pattern is formed (backside annealing).

  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.

  The technique according to the present invention can also be applied to a laser annealing apparatus that heats the semiconductor wafer W by laser beam irradiation.

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 65 Heat processing space 71 Base ring 72 Support ring 73 Connection member 75,175 Support member 79,179 Protrusion 120 Radiation Thermometer 176 First support 177 Second support 278 Soaking ring 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;
Holding means for holding the substrate in the chamber;
A flash lamp for irradiating flash light on one surface of the substrate held by the holding means;
A halogen lamp for irradiating light to the other surface of the substrate held by the holding means;
Temperature measuring means for measuring the temperature of the substrate heated by light irradiation from the halogen lamp;
With
The holding means includes a plurality of support members that are supported from the outer peripheral end side of the substrate,
The plurality of support members are formed of silicon carbide, aluminum nitride, graphite coated with silicon carbide, or silicon nitride ,
Each of the plurality of support members is
A first support inclined obliquely downward from the outside of the substrate toward the center;
A second support that is provided so as to extend along the horizontal direction from the tip of the first support, and that contacts the lower surface of the substrate.
The heat treatment apparatus, wherein the second support includes a protrusion that makes point contact with the lower surface of the substrate . The heat treatment apparatus according to claim 1, wherein
An annular member placed on the second support and surrounding the periphery of the substrate in a non-contact manner;
The annular member is formed of silicon carbide, aluminum nitride, graphite coated with silicon carbide, or silicon nitride . In the heat treatment apparatus according to claim 1 or 2 ,
The heat treatment apparatus, wherein the plurality of support members are fixed to a quartz ring having an inner diameter larger than a diameter of the substrate . The heat treatment apparatus according to claim 3 , wherein
The heat treatment apparatus, wherein the quartz ring is fixedly installed in the chamber . In the heat processing apparatus in any one of Claims 1-4 ,
A heat treatment apparatus , further comprising pressure maintaining means for maintaining the inside of the chamber at a pressure of 50 Pa or more and 500 Pa or less . The heat treatment apparatus according to claim 5 , wherein
The pressure maintaining means includes
Exhaust means for exhausting the atmosphere in the chamber;
Gas supply means for supplying an inert gas into the chamber;
A heat treatment apparatus characterized by supplying an inert gas into the chamber and maintaining the pressure in the chamber at 50 Pa or more and 500 Pa while exhausting from the chamber .

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