JP6539498B2 - Heat treatment equipment - Google Patents

Description

  The present invention relates to a heat treatment apparatus that heats a thin plate-shaped precision electronic substrate (hereinafter, simply referred to as a “substrate”) such as a semiconductor wafer by irradiating the substrate with flash light.

  In the semiconductor device manufacturing process, impurity introduction is an essential step for forming a pn junction in a semiconductor wafer. At present, impurity introduction is generally performed by ion implantation and subsequent annealing. The ion implantation method is a technology for physically implanting impurities by ionizing elements of impurities such as boron (B), arsenic (As), and phosphorus (P) and causing them to collide with a semiconductor wafer at a high acceleration voltage. 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 too deep than required, which may cause a problem in forming a good device.

  Therefore, flash lamp annealing (FLA) has recently attracted attention as an annealing technique for heating a semiconductor wafer in a very short time. Flash lamp annealing is a semiconductor wafer in which impurities are implanted by irradiating flash light onto the surface of the semiconductor wafer using a xenon flash lamp (hereinafter simply referred to as a xenon flash lamp when it is referred to as “flash lamp”). It is a heat treatment technology that raises the temperature of only the surface for a very short time (a few milliseconds or less).

  The emission spectral distribution of the xenon flash lamp is in the ultraviolet region to the near infrared region, has a shorter wavelength than that of the conventional halogen lamp, and substantially matches the basic absorption band of a silicon semiconductor wafer. Therefore, when the semiconductor wafer is irradiated with flash light from the xenon flash lamp, it is possible to rapidly increase the temperature of the semiconductor wafer because the amount of transmitted light is small. It has also been found that only the vicinity of the surface of the semiconductor wafer can be selectively heated if the flash light irradiation is performed for an extremely short time of several milliseconds or less. For this reason, if the temperature rise for a very short time by a xenon flash lamp, only impurity activation can be performed without deeply diffusing the impurity.

  As a heat treatment apparatus using such a xenon flash lamp, for example, in Patent Documents 1 and 2, a pulse light emitting lamp such as a flash lamp is disposed on the front side of a semiconductor wafer, and a continuous lighting lamp such as a halogen lamp on the back side. It is disclosed to arrange and perform the desired heat treatment by combination thereof. In the heat treatment apparatus disclosed in Patent Documents 1 and 2, the semiconductor wafer is preheated to a certain temperature by a halogen lamp or the like, and thereafter heated to a desired processing temperature by pulse heating from the flash lamp.

  By the way, in a heat treatment apparatus using a flash lamp, the surface temperature of the semiconductor wafer is rapidly increased instantaneously because the surface of the semiconductor wafer is instantaneously irradiated with flash light having extremely high energy, while the back surface temperature is so much It does not rise to For this reason, rapid thermal expansion occurs only on the surface of the semiconductor wafer, and the semiconductor wafer is deformed so as to be warped with the upper surface convex. Then, at the next moment, the semiconductor wafer is deformed so as to be warped with the lower surface convex by reaction. As a result, the wafer vibrates violently on the susceptor supporting the semiconductor wafer, and the semiconductor wafer jumps from the susceptor, and further, there is a problem that the support pin of the semiconductor wafer or the susceptor is broken by impact.

  For this reason, according to Patent Document 3, the semiconductor wafer is supported at a distance of 0.5 mm to 3 mm from the attenuation plate, and the semiconductor is pressed by the gas pressure of the gas sandwiched between the attenuation plate and the semiconductor wafer at the time of flash light irradiation. It has been proposed to damp the vibrations of the wafer.

Japanese Patent Application Laid-Open No. 60-258928 Japanese Patent Application Publication No. 2005-527972 Japanese Patent Application Publication No. 2007-519232

  However, even with the technique as disclosed in Patent Document 3, the jumping of the semiconductor wafer can not be suppressed at the time of flash light irradiation, and there still remains the risk of breakage of the semiconductor wafer or the support pin at the time of flash light irradiation. ing.

  The present invention has been made in view of the above problems, and an object thereof is to provide a heat treatment apparatus capable of preventing jumping and cracking of a substrate at the time of flash light irradiation.

In order to solve the above-mentioned problems, the invention according to claim 1 is a heat treatment apparatus for heating a substrate by irradiating the substrate with flash light, the chamber for housing the substrate, and a plurality of support pins provided on the upper surface. A flat susceptor configured to support the substrate at a predetermined distance from the upper surface, a base fixedly installed on the wall of the chamber and provided to cover the lower side of the susceptor, and the base An elastic member for supporting the susceptor in the chamber, and a flash lamp for irradiating a substrate supported by the susceptor with a flash light.

  The invention of claim 2 is the heat treatment apparatus according to the invention of claim 1, wherein the elastic member is an air spring.

  The invention according to claim 3 is characterized in that, in the heat treatment apparatus according to the invention according to claim 1, the elastic member is a coil spring.

  According to the first to third aspects of the present invention, since the susceptor for supporting the substrate is supported by the elastic member, the force acting on both the susceptor and the substrate when the substrate is deformed suddenly at the time of flash light irradiation It can be mitigated, and substrate jumping and cracking during flash light irradiation can be prevented.

It is a longitudinal cross-sectional view which shows the structure of the heat processing apparatus which concerns on this invention. It is a side view of a holding part. It is a top view of a susceptor. It is the figure which expanded the vicinity of an air spring. It is a top view of a transfer mechanism. It is a side view of a transfer mechanism. It is a top view showing arrangement of a plurality of halogen lamps. It is a figure which shows the state in which the semiconductor wafer was hold | maintained by the holding part. It is a figure which shows the state of the moment the flash light was irradiated to the semiconductor wafer.

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

  FIG. 1 is a longitudinal sectional view showing the 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 which heats the semiconductor wafer W by irradiating the semiconductor wafer W having a disk shape with a flash light as a substrate. The size of the semiconductor wafer W to be processed is not particularly limited, and is, for example, φ300 mm or φ450 mm. Impurities are implanted into the semiconductor wafer W before being carried into the heat treatment apparatus 1, and activation processing of the impurities implanted by the heat treatment by the heat treatment apparatus 1 is performed. In FIG. 1 and the subsequent drawings, the dimensions and the numbers of the respective parts are exaggerated or simplified as necessary for easy understanding.

  The heat treatment apparatus 1 includes a chamber 6 for housing a semiconductor wafer W, a flash heating unit 5 containing a plurality of flash lamps FL, and a halogen heating unit 4 containing a plurality of halogen lamps HL. 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 further includes a holding unit 7 for holding the semiconductor wafer W in a horizontal posture inside the chamber 6, and a transfer mechanism 10 for delivering the semiconductor wafer W between the holding unit 7 and the outside of the apparatus. Equipped with The heat treatment apparatus 1 further includes a control unit 3 that controls the respective operation mechanisms provided in the halogen heating unit 4, the flash heating unit 5, and the chamber 6 to execute the heat treatment of the semiconductor wafer W.

  The chamber 6 is configured by mounting quartz chamber windows on the upper and lower sides of a cylindrical chamber side 61. The chamber side 61 has a generally cylindrical shape with an open top and bottom, the upper opening is fitted with the upper chamber window 63 and closed, and the lower opening is fitted with the lower chamber window 64 and closed ing. The upper chamber window 63 constituting the ceiling of the chamber 6 is a disk-shaped member formed 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 of the chamber 6 is also a disk-shaped member made of quartz and functions as a quartz window for transmitting the light from the halogen heating unit 4 into the chamber 6.

  In addition, a reflection ring 68 is attached to the upper portion of the inner wall surface of the chamber side portion 61, and a reflection ring 69 is attached to the lower portion. The reflection rings 68 and 69 are both formed in an annular shape. The upper reflective ring 68 is mounted by fitting from the upper side of the chamber side 61. On the other hand, the lower reflection ring 69 is mounted by being fitted from the lower side of the chamber side 61 and fixed with a screw (not shown). That is, the reflection rings 68 and 69 are both detachably mounted on the chamber side 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 61 and the reflection rings 68 and 69 is defined as a heat treatment space 65.

  By mounting the reflection rings 68 and 69 on the chamber side 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 61 to which the reflective rings 68 and 69 are not attached, the lower end surface of the reflective ring 68 and the upper end surface of the reflective ring 69 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 unit 7 that holds the semiconductor wafer W.

  The chamber side 61 and the reflection rings 68 and 69 are formed of a metal material (for example, stainless steel) which is excellent in strength and heat resistance. The inner peripheral surfaces of the reflection rings 68 and 69 are mirror-polished by electrolytic nickel plating.

  In the chamber side portion 61, a transfer opening (furnace port) 66 for carrying in and out the semiconductor wafer W with respect to the chamber 6 is formed. The transfer opening 66 can be opened and closed by a gate valve 185. The transfer opening 66 is connected in communication with 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 from the transfer opening 66 through the recess 62 and the semiconductor wafer W is unloaded 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 is made a closed space.

Further, a gas supply hole 81 for supplying a processing gas (in the present embodiment, nitrogen gas (N ₂ )) to the heat treatment space 65 is formed on the upper 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 communicatively connected to the gas supply pipe 83 via a buffer space 82 formed annularly in the side wall of the chamber 6. The gas supply pipe 83 is connected to a nitrogen gas supply source 85. Further, a valve 84 is interposed 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 holes 81, and is supplied from the gas supply holes 81 into the heat treatment space 65. The processing gas is not limited to nitrogen gas, and may be an inert gas such as argon (Ar) or helium (He), or oxygen (O ₂ ), hydrogen (H ₂ ), chlorine (Cl ₂ ), It may be a reactive gas such as hydrogen chloride (HCl), ozone (O ₃ ), ammonia (NH ₃ ) or the like.

  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 lower position than the recess 62, and may be provided in the reflection ring 69. The gas exhaust hole 86 is connected in communication with the gas exhaust pipe 88 via a buffer space 87 formed annularly in the side wall of the chamber 6. The gas exhaust pipe 88 is connected to the exhaust unit 190. Further, a valve 89 is interposed 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 exhausted from the gas exhaust hole 86 through the buffer space 87 to the gas exhaust pipe 88. 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 190 may be a mechanism provided in the heat treatment apparatus 1 or may be a utility of a factory where the heat treatment apparatus 1 is installed.

  In addition, a gas exhaust pipe 191 for exhausting 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 side view of the holder 7. The holder 7 for holding the semiconductor wafer W in the chamber 6 is configured to include a base 71, a susceptor 74 and an air spring 72. The base 71 is a plate-like member formed of quartz, and is mounted on the wall surface of the chamber 6 by being mounted on the bottom surface of the recess 62.

  FIG. 3 is a plan view of the susceptor 74. As shown in FIG. The susceptor 74 is a substantially circular flat member made of quartz. The diameter of the susceptor 74 is larger than the diameter of the semiconductor wafer W. That is, the susceptor 74 has a larger planar size than the semiconductor wafer W. A plurality of support pins 75 are provided upright on the top surface of the susceptor 74. In the present embodiment, a total of six support pins 75 are erected at every 60 ° along the circumference of a circle concentric with the outer circumference of the susceptor 74. The diameter of the circle in which the six support pins 75 are arranged (the distance between the opposing support pins 75) is smaller than the diameter of the semiconductor wafer W (for example, if the diameter of the semiconductor wafer W is 300 mm, the support pins 75 are arranged) The diameter of the circle is 280 mm). Each of the six support pins 75 is formed of quartz. Further, a plurality of guide pins or guide rings are provided on the upper surface of the susceptor 74 so as to surround the periphery of the semiconductor wafer W supported by the support pins 75 (all not shown). The guide pins or guide rings prevent the horizontal misalignment of the semiconductor wafer W supported by the six support pins 75. Furthermore, four through holes 79 are formed in the susceptor 74 so that lift pins 12 of the transfer mechanism 10, which will be described later, pass through for transfer of the semiconductor wafer W.

  As shown in FIG. 2, the susceptor 74 is installed on the base 71 by sandwiching a plurality of (six in the present embodiment) air springs 72. That is, the plurality of air springs 72 are provided on the upper surface of the base 71, and the susceptor 74 is supported by the plurality of air springs 72.

  FIG. 4 is an enlarged view of the vicinity of the air spring 72. As shown in FIG. The air spring 72 is a spring utilizing the elastic force of compressed air. Various known types of air springs can be employed as the air spring 72. For example, a bellows type in which compressed air is enclosed in an internal space of a rubber bellows closed with a plate member can be used. .

  The base 71 is fixedly installed on the wall surface of the chamber 6, and the susceptor 74 is supported on the upper surface of the base 71 via a plurality of air springs 72. Although the base 71 is stably supported by the chamber 6, the susceptor 74 can be provided with a suspension function by supporting the susceptor 74 via the air spring 72 thereon.

  The semiconductor wafer W is supported by point contact by a plurality of support pins 75 provided upright on the upper surface of the susceptor 74 supported by the air spring 72. That is, the semiconductor wafer W is supported at a predetermined distance from the upper surface of the susceptor 74 via the plurality of support pins 75. As a result, a thin gas layer is present between the back surface of the semiconductor wafer W supported by the susceptor 74 and the top surface of the susceptor 74.

  FIG. 5 is a plan view of the transfer mechanism 10. 6 is a side view of the transfer mechanism 10. As shown in FIG. The transfer mechanism 10 includes two transfer arms 11. The transfer arm 11 has an arc shape along the generally annular recess 62. Two lift pins 12 are erected on each transfer arm 11. Each transfer arm 11 is rotatable by a horizontal movement mechanism 13. The horizontal movement mechanism 13 transfers the pair of transfer arms 11 to the holding unit 7 at the transfer operation position (solid line position in FIG. 5) for transferring the semiconductor wafer W and the semiconductor wafer W held by the holding unit 7. Horizontal movement is performed between a retracted position (two-dot chain line position in FIG. 5) which does 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 one motor using a link mechanism. It may be moved.

  Further, the pair of transfer arms 11 are moved up and down together with the horizontal movement mechanism 13 by the elevation mechanism 14. When the lifting mechanism 14 lifts the pair of transfer arms 11 at the transfer operation position, a total of four lift pins 12 pass through the through holes 79 (see FIG. 3) formed in the susceptor 74 and the lift pins 12 are The upper end protrudes from the upper surface of the susceptor 74. On the other hand, when the lifting mechanism 14 lowers the pair of transfer arms 11 at the transfer operation position to extract the lift pins 12 from the through holes 79 and the horizontal movement mechanism 13 moves the pair of transfer arms 11 to open. The transfer arm 11 moves to the retracted position. The retracted position of the pair of transfer arms 11 is a position not overlapping the semiconductor wafer W supported by the susceptor 74 when viewed from the top. An exhaust mechanism (not shown) is provided in the vicinity of the portion where the drive unit (horizontal movement mechanism 13 and lifting mechanism 14) of transfer mechanism 10 is provided, and the atmosphere around the drive unit of transfer mechanism 10 is provided. Are discharged to the outside of the chamber 6.

  Returning to FIG. 1, the flash heating unit 5 provided above the chamber 6 is a light source consisting of a plurality (30 in the present embodiment) of xenon flash lamps FL inside the housing 51 and the light source above And a reflector 52 provided to cover the A lamp light emission window 53 is attached to the bottom of the housing 51 of the flash heating unit 5. The lamp light emission window 53 which constitutes the floor of the flash heating unit 5 is a plate-like quartz window formed 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.

  The plurality of flash lamps FL are rod-shaped lamps each having a long cylindrical shape, and the longitudinal direction of each is along the main surface of the semiconductor wafer W held by the holder 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-like glass tube (discharge tube) in which xenon gas is enclosed and an anode and a cathode connected to a capacitor are disposed at both ends, and attached on the outer peripheral surface of the glass tube And a trigger electrode. Since xenon gas is an insulator electrically, no electricity flows in the glass tube under normal conditions even if charge is stored in the capacitor. However, when a high voltage is applied to the trigger electrode to break the insulation, the electricity stored in the capacitor instantaneously flows 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 stored in advance in the capacitor is converted into an extremely short light pulse of 0.1 milliseconds to 100 milliseconds. It is characterized in that it can emit extremely intense light as compared to a light source.

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

  The halogen heating unit 4 provided below the chamber 6 incorporates a plurality of (40 in the present embodiment) halogen lamps HL inside the housing 41. The halogen heating unit 4 is a light irradiation unit that heats the semiconductor wafer W by performing light irradiation on the heat treatment space 65 from the lower side of the chamber 6 through the lower chamber window 64 with a plurality of halogen lamps HL.

  FIG. 7 is a plan view showing the arrangement of the plurality of halogen lamps HL. The plurality of halogen lamps HL are disposed in a region wider than the main surface of the disk-shaped semiconductor wafer W held by the holding portion 7. Further, in the main surface of the semiconductor wafer W, a plurality of halogen lamps HL are disposed in a region facing the lower surface.

  As shown in FIGS. 1 and 7, forty halogen lamps HL are arranged in two upper and lower stages. The twenty halogen lamps HL are disposed in the upper stage near the holding unit 7, and the twenty halogen lamps HL are disposed in the lower stage further from the holding unit 7 than the upper stage. Each halogen lamp HL is a rod-shaped lamp having a long cylindrical shape. The upper and lower 20 halogen lamps HL are arranged such that their longitudinal directions are parallel to each other along the main surface of the semiconductor wafer W held by the holder 7 (that is, along the horizontal direction). There is. Therefore, the plane formed by the arrangement of the halogen lamps HL in the upper and lower stages is a horizontal plane.

  Further, as shown in FIG. 7, the disposition 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 and lower portions. There is. That is, in both the upper and lower portions, the disposition pitch of the halogen lamps HL is shorter in the peripheral portion than in the central portion of the lamp arrangement. For this reason, it is possible to perform irradiation of a larger amount of light at the peripheral portion of the semiconductor wafer W which is likely to cause a temperature drop during heating by light irradiation from the halogen heating unit 4.

  Further, a lamp group consisting of the halogen lamp HL in the upper stage and a lamp group consisting of the halogen lamp HL in the lower stage are arranged so as to cross in a lattice shape. That is, a total of 40 halogen lamps HL are disposed so that the longitudinal direction of the 20 halogen lamps HL disposed in the upper stage and the longitudinal direction of the 20 halogen lamps HL disposed in the lower stage are orthogonal to each other. There is.

  The halogen lamp HL is a filament type light source which causes the filament to glow to emit light by energizing the filament disposed inside the glass tube. Inside the glass tube, a gas in which a small amount of a halogen element (iodine, bromine or the like) is introduced into an inert gas such as nitrogen or argon is enclosed. By introducing a halogen element, it is possible to set the temperature of the filament to a high temperature while suppressing the breakage of the filament. Therefore, the halogen lamp HL has a characteristic that it has a long life and can continuously emit strong light as compared with a normal incandescent lamp. That is, the halogen lamp HL is a continuous lighting lamp which emits light continuously for at least one second or more. Further, since the halogen lamp HL is a rod-like lamp, it has a long life, and by arranging the halogen lamp HL in the horizontal direction, the radiation efficiency to the upper semiconductor wafer W becomes excellent.

  In addition, a reflector 43 is provided below the two-stage halogen lamp HL also in the housing 41 of the halogen heating unit 4 (FIG. 1). The reflector 43 reflects the light emitted from the plurality of halogen lamps HL to the side of the heat treatment space 65.

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

  In addition to the above configuration, the heat treatment apparatus 1 prevents excessive temperature rise of the halogen heating unit 4, the flash heating unit 5 and the chamber 6 due to the heat energy generated from the halogen lamp HL and the flash lamp FL during the heat treatment of the semiconductor wafer W Because of that, it has various cooling structures. For example, the wall of the chamber 6 is provided with a water cooling pipe (not shown). In addition, 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, the processing procedure of the semiconductor wafer W in the heat treatment apparatus 1 will be described. Here, the semiconductor wafer W to be treated is a semiconductor substrate to which impurities (ions) are added by ion implantation. The activation of the impurities is performed by the flash light irradiation heat treatment (annealing) by the heat treatment apparatus 1. The processing procedure of the heat treatment apparatus 1 described below proceeds by the control unit 3 controlling each operation mechanism of the heat treatment apparatus 1.

  First, the valve 84 for air supply is opened, and the valves 89 and 192 for exhaust are opened to start air supply / exhaust into the chamber 6. When the valve 84 is opened, nitrogen gas is supplied from the gas supply hole 81 to the heat treatment space 65. When the valve 89 is opened, the gas in the chamber 6 is exhausted from the gas exhaust hole 86. 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, by opening the valve 192, the gas in the chamber 6 is also exhausted from the transfer opening 66. Furthermore, the atmosphere around the drive unit of the transfer mechanism 10 is also exhausted by an exhaust mechanism (not shown). During the heat treatment of the semiconductor wafer W in the heat treatment apparatus 1, nitrogen gas is continuously supplied to the heat treatment space 65, and the supply amount thereof is appropriately changed in accordance with the treatment process.

  Subsequently, the gate valve 185 is opened to open the transfer opening 66, and the semiconductor wafer W after ion implantation is carried into the heat treatment space 65 in the chamber 6 through the transfer opening 66 by the transfer robot outside the apparatus. The semiconductor wafer W carried in by the transfer robot advances to a position immediately above the holding unit 7 and stops there. Then, when the pair of transfer arms 11 of the transfer mechanism 10 horizontally move from the retracted position to the transfer operation position and ascends, the lift pins 12 protrude from the upper surface of the susceptor 74 through the through holes 79 and the semiconductor wafer W Receive

  After the semiconductor wafer W is placed on the lift pins 12, the transfer robot exits the heat treatment space 65, and the transfer opening 66 is closed by the gate valve 185. Then, the pair of transfer arms 11 is lowered, so that the semiconductor wafer W is transferred from the transfer mechanism 10 to the susceptor 74 of the holding unit 7 and held horizontally from below. The semiconductor wafer W is pattern-formed and held by the holding unit 7 with the surface on which the impurity is implanted as the upper surface. The pair of transfer arms 11 lowered to below the susceptor 74 is retracted by the horizontal movement mechanism 13 to the retracted position.

  FIG. 8 is a view showing a state where the semiconductor wafer W is held by the holding unit 7. In FIG. 8 and FIG. 9 described later, each element is drawn in an exaggerated manner for the convenience of description. As described above, the susceptor 74 of the holder 7 is supported by the plurality of air springs 72 so as to have a suspension function. A plurality of support pins 75 are erected on the upper surface of the susceptor 74, and the semiconductor wafer W delivered from the transfer mechanism 10 is supported by the plurality of support pins 75 by point contact, and thus the holding portion 7. Will be held by A space corresponding to the height of the support pins 75 exists between the back surface (main surface opposite to the front surface) of the semiconductor wafer W held by the holding portion 7 and the top surface of the susceptor 74. That is, a thin gas layer is sandwiched between the back surface of the semiconductor wafer W held by the holder 7 and the top surface of the susceptor 74.

  After the semiconductor wafer W is horizontally held by the holding unit 7 from the lower side, the 40 halogen lamps HL of the halogen heating unit 4 are simultaneously turned on to start preheating (assist heating). 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 formed of quartz, the base 71 and the susceptor 74. The semiconductor wafer W is preheated by receiving light irradiation from the halogen lamp HL, and the temperature rises.

  When performing preheating with the halogen lamp HL, the temperature of the semiconductor wafer W is measured by a temperature sensor (not shown). The measured temperature of the semiconductor wafer W is transmitted to the control unit 3. The control unit 3 controls the output of the halogen lamp HL while monitoring whether or not the temperature of the semiconductor wafer W heated by irradiation of light from the halogen lamp HL has reached a predetermined preheating temperature T1. That is, the control unit 3 performs feedback control of 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.) without the risk that the impurity added to the semiconductor wafer W is diffused by heat. .

  After the temperature of the semiconductor wafer W reaches the preheating temperature T1, the control unit 3 temporarily maintains the semiconductor wafer W at the preheating temperature T1. Specifically, when the temperature of the semiconductor wafer W reaches the preheating temperature T1, the control unit 3 adjusts the output of the halogen lamp HL to maintain the temperature of the semiconductor wafer W substantially at the preheating temperature T1. .

  By performing such preheating with the halogen lamp HL, the entire semiconductor wafer W is uniformly heated to the preheating temperature T1. At the stage of preheating by the halogen lamp HL, the temperature of the peripheral portion of the semiconductor wafer W which is more likely to generate heat tends to be lower than that at the central portion, but the arrangement density of the halogen lamp HL in the halogen heating unit 4 is The region facing the peripheral portion is higher than the region facing the central portion of the semiconductor wafer W (see FIG. 7). As a result, the amount of light irradiated to the peripheral portion of the semiconductor wafer W that easily dissipates heat increases, and the in-plane temperature distribution of the semiconductor wafer W in the preliminary heating stage can be made uniform. Furthermore, since the inner peripheral surface of the reflective ring 69 mounted on the chamber side portion 61 is a mirror surface, the inner peripheral surface of the reflective ring 69 increases the amount of light reflected toward the peripheral portion of the semiconductor wafer W, The in-plane temperature distribution of the semiconductor wafer W in the preheating stage can be made more uniform.

  When the temperature of the semiconductor wafer W reaches the preheating temperature T1 due to light irradiation from the halogen lamp HL and a predetermined time has elapsed, the flash lamp FL of the flash heating unit 5 irradiates the surface of the semiconductor wafer W with flash light . At this time, a part of the flash light emitted from the flash lamp FL directly goes into the chamber 6, and the other part is once reflected by the reflector 52 and then goes into the chamber 6, and these flash lights are Flash heating of the semiconductor wafer W is performed by the irradiation.

  Since the flash heating is performed by flash light (flash light) irradiation from the flash lamp FL, the surface temperature of the semiconductor wafer W can be raised in a short time. That is, the flash light emitted from the flash lamp FL has an extremely short irradiation time of 0.1 milliseconds or more and 100 milliseconds or less, in which electrostatic energy previously stored in the capacitor is converted into an extremely short light pulse. It is a strong flashlight. Then, the surface temperature of the semiconductor wafer W flash-heated by the flash light irradiation from the flash lamp FL instantaneously rises to the processing temperature T2 of 1000 ° C. or higher, and the impurity implanted into the semiconductor wafer W is activated. After that, the surface temperature drops rapidly. As described above, since the heat treatment apparatus 1 can raise and lower the surface temperature of the semiconductor wafer W in a very short time, the activation of the impurities is suppressed while the diffusion of the impurities injected into the semiconductor wafer W is suppressed. Can. Since the time required for activating the impurity is extremely short compared to the time required for its thermal diffusion, the activation can be performed even for a short time when diffusion of about 0.1 milliseconds to 100 milliseconds does not occur. Complete.

  FIG. 9 is a view showing a state of the moment when the semiconductor wafer W is irradiated with the flash light. While the surface temperature of the semiconductor wafer W instantaneously rises to the processing temperature T2 of 1000 ° C. or more by the flash light irradiation, the instantaneous back surface temperature does not rise so much from the preheating temperature T1. That is, a large temperature difference occurs instantaneously between the front and back surfaces of the semiconductor wafer W. As a result, as shown in FIG. 9, rapid thermal expansion occurs only on the front surface of the semiconductor wafer W, and the rear surface hardly thermally expands, so the semiconductor wafer W momentarily warps so that the front surface becomes a convex surface. Subsequently, at the next moment, heat is conducted also from the front surface to the back surface of the semiconductor wafer W, and the back surface is warped to be a convex surface due to the reaction of the warpage with the above surface as a convex surface. After that, the semiconductor wafer W vibrates repeatedly so that the front surface and the back surface alternately become convex.

  Here, as in the prior art, when the susceptor 74 is fixedly installed, if the semiconductor wafer W warps so that the surface is a convex surface, the edge portion of the semiconductor wafer W is on the upper surface of the susceptor 74. collide. Conversely, when the semiconductor wafer W warps so that the back surface is convex, the central portion of the semiconductor wafer W collides with the upper surface of the susceptor 74. As a result, the semiconductor wafer W may jump, the upper surface of the susceptor 74 may be scratched, and in the worst case, the wafer may be cracked. In addition, since a large force acts on the support pins 75 in direct contact with the semiconductor wafer W due to the deformation of the semiconductor wafer W, the support pins 75 may be broken.

  Therefore, in the heat treatment apparatus 1 according to the present invention, the susceptor 74 is supported by the air spring 72 in the chamber 6. The susceptor 74 is provided with a suspension function by supporting the susceptor 74 with the air spring 72, and can absorb the force acting on the susceptor 74 due to the deformation of the semiconductor wafer W at the time of flash light irradiation. Thereby, the force acting on both the semiconductor wafer W and the susceptor 74 at the time of flash light irradiation can be alleviated, and jumping and cracking of the semiconductor wafer W and breakage of the susceptor 74 (particularly, breakage of the support pin 75) can be prevented. be able to.

  After the flash heating process is completed, the halogen lamp HL is turned off after a predetermined time has elapsed. Thereby, the semiconductor wafer W is rapidly cooled from the preheating temperature T1. The temperature of the semiconductor wafer W during temperature decrease is measured by a temperature sensor, and the measurement result is transmitted to the control unit 3. The control unit 3 monitors whether the temperature of the semiconductor wafer W has dropped to a predetermined temperature based on the measurement result. Then, after the temperature of the semiconductor wafer W is lowered to a predetermined temperature or less, the pair of transfer arms 11 of the transfer mechanism 10 horizontally move from the retracted position to the transfer operation position again to rise, whereby the lift pins 12 are susceptors The semiconductor wafer W after heat treatment which protrudes from the upper surface of the substrate 74 is received from the susceptor 74. Subsequently, the transfer opening 66 closed by the gate valve 185 is opened, the semiconductor wafer W placed on the lift pins 12 is carried out 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 complete.

  In the present embodiment, by supporting the semiconductor wafer W by a plurality of support pins 75 erected on the susceptor 74, a thin gas layer is sandwiched between the back surface of the semiconductor wafer W and the top surface of the susceptor 74. The susceptor 74 is supported by an air spring 72. Thereby, the force acting on both the semiconductor wafer W and the susceptor 74 due to the deformation of the semiconductor wafer W can be relaxed. As a result, jumping and cracking of the semiconductor wafer W can be prevented at the time of flash light irradiation, and breakage of the susceptor 74 can also be prevented.

  Although the embodiments of the present invention have been described above, various modifications can be made to the present invention other than those described above without departing from the scope of the present invention. For example, although the susceptor 74 is supported by the air spring 72 in the above embodiment, the present invention is not limited to this. For example, the susceptor 74 may be supported by a coil spring made of aluminum. Even when the susceptor 74 is supported by the coil spring, the force acting on both the semiconductor wafer W and the susceptor 74 can be relaxed, and the same effect as that of the above embodiment can be obtained. That is, if the susceptor 74 is supported in the chamber 6 by an elastic member such as the air spring 72 or a coil spring, the force acting on both the semiconductor wafer W and the susceptor 74 can be relieved, as in the above embodiment. You can get the effect.

  Moreover, in the said embodiment, although 30 flash lamps FL were provided in the flash heating part 5, it is not limited to this, The number of flash lamps FL can be made into arbitrary numbers. . Further, the flash lamp FL is not limited to the 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 any number may be used as long as a plurality of the lamps are disposed in the upper and lower stages.

  The substrate to be treated 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 flat panel display such as a liquid crystal display or a substrate for a solar cell. Further, the technique according to the present invention may be applied to heat treatment of a high dielectric constant gate insulating film (High-k film), bonding of metal and silicon, or crystallization of polysilicon.

DESCRIPTION OF SYMBOLS 1 heat treatment apparatus 3 control part 4 halogen heating part 5 flash heating part 6 chamber 7 holder 10 transfer mechanism 64 lower chamber window 65 heat processing space 71 base 72 air spring 74 susceptor 75 support pin FL flash lamp HL halogen lamp W semiconductor Wafer

Claims (3)

A thermal processing apparatus for heating a substrate by irradiating the substrate with flash light, comprising:
A chamber for containing a substrate,
A flat susceptor configured to support the substrate at a predetermined distance from the upper surface through a plurality of support pins provided on the upper surface;
A base fixedly installed on the wall of the chamber and provided to cover the lower side of the susceptor ;
An elastic member provided on the upper surface of the base and supporting the susceptor in the chamber;
A flash lamp for irradiating the substrate supported by the susceptor with flash light;
A heat treatment apparatus comprising: In the heat treatment apparatus according to claim 1,
The heat treatment apparatus, wherein the elastic member is an air spring. In the heat treatment apparatus according to claim 1,
The heat treatment apparatus, wherein the elastic member is a coil spring.

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