JP2008288520A - Thermal treatment equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide thermal treatment equipment that can control the life of a flash lamp from being deteriorated. <P>SOLUTION: A plurality of flash lamps FL are installed in a row inside a liquid tank 51, the flash lamps irradiating flash light. Both ends of the flash lamp FL supplied with electric power project out of the wall surface of the liquid tank 51 through a seal material. A chiller 55 fills the liquid tank 51 by recurrent supply of cooling liquid (deionized water) into the interior. When the plurality of flash lamps FL emit flash light at a flash heating time, the plurality of the flash lamps FL are immersed in the cooling liquid supplied to the liquid tank 51 from the chiller 55. For this reason, even if the interior of glass tube of the flash lamp FL is exposed to high-temperature plasma, temperature rise is controlled since the total flash lamps FL are cooled by the cooling liquid, as a result enabling the life of the flash lamp FL to be dramatically lengthened. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

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

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

  For this reason, a semiconductor into which ions are implanted by irradiating the surface of a semiconductor wafer with flash light (flash light) using a xenon flash lamp (hereinafter, simply referred to as “flash lamp” means xenon flash lamp). Techniques have been proposed in which only the surface of a wafer is heated in a very short time (several milliseconds or less) (for example, Patent Documents 1 and 2). 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 is irradiated 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 a xenon flash lamp, only the ion activation can be performed without diffusing ions deeply.

  In a heat treatment apparatus that performs flash heating as described above, air is supplied to and exhausted from a lamp house in which a lamp is disposed in order to cool a xenon flash lamp. As a result, the heat in the lamp house is discharged and the xenon flash lamp itself is also cooled by the air.

JP 2004-55821 A JP 2004-88052 A

  However, since flash light with extremely large energy is emitted during flash heating, the inner wall of the quartz glass lamp tube is exposed to high-temperature plasma, the temperature rises, and the life of the lamp tube deteriorates. In particular, a device having a relatively short pulse width of flash light requires a higher current density than that of flash light irradiation having a relatively long pulse width. As a result, the plasma density in the lamp tube increases and the life is extremely short. Become.

  Xenon flash lamps used for flash heating are very expensive. Especially in the devices disclosed in Patent Documents 1 and 2, dozens of xenon flash lamps are used. There was a problem that the running cost was increased as it was.

  Further, when the lamp tube temperature suddenly increased during flash heating, the lamp tube sometimes burst. In an apparatus that uses dozens of xenon flash lamps as disclosed in Patent Documents 1 and 2, if one lamp tube bursts, the adjacent lamp tubes are damaged one after another by the impact. There was also a risk of problems.

  This invention is made | formed in view of the said subject, and aims at providing the heat processing apparatus which can suppress the lifetime deterioration of a flashlamp.

  In order to solve the above-mentioned problems, a first aspect of the present invention is a heat treatment apparatus for heating a substrate by irradiating the substrate with flash light, a chamber having a chamber window that transmits flash light at an upper portion thereof, and the chamber A holding means for holding the substrate in a horizontal position therein, a liquid tank disposed above the chamber and having a radiation window for transmitting flash light at a bottom thereof, and disposed in the liquid tank, in a rod-shaped discharge tube And a plurality of flash lamps that emit flash light by discharging between the anode and the cathode, and a coolant supply means that supplies a coolant to the liquid tank, wherein the plurality of flash lamps emit flash light. The plurality of flash lamps are immersed in the coolant supplied from the coolant supply means to the liquid tank. And butterflies.

  The invention according to claim 2 is the heat treatment apparatus according to claim 1, wherein the plurality of flash lamps are aligned in a horizontal direction in the liquid tank with the anode-cathode direction aligned, The cooling liquid supply means supplies the cooling liquid from the cathode side of the plurality of flash lamps.

  The invention according to claim 3 is the heat treatment apparatus according to claim 1 or 2, wherein the outer tank that receives the coolant leaked from the liquid tank and the coolant flowing into the outer tank are detected. And a leakage detection means.

  According to the first to third aspects of the present invention, when the flash lamp emits flash light, the flash lamp is immersed in the coolant, so that the temperature rise of the flash lamp due to light emission is suppressed, and the life of the flash lamp is deteriorated. Can be suppressed.

  In particular, according to the second aspect of the present invention, since the coolant is supplied from the cathode side of the flash lamp, which tends to have a higher temperature, the flash lamp can be appropriately cooled.

  In particular, according to the invention of claim 3, even if the coolant leaks from the liquid tank, the liquid can be recovered and the leak of the liquid can be detected.

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

  First, the overall configuration of the heat treatment apparatus according to the present invention will be outlined. FIG. 1 is a side sectional view showing a configuration of a heat treatment apparatus 1 according to the present invention. The heat treatment apparatus 1 is a flash lamp annealing apparatus that irradiates a substantially circular semiconductor wafer W as a substrate with flash (flash light) and heats the semiconductor wafer W.

  The heat treatment apparatus 1 includes a substantially cylindrical chamber 6 that accommodates a semiconductor wafer W, and a light irradiation unit 5 that includes a plurality of flash lamps FL. Further, the heat treatment apparatus 1 includes a control unit 3 that controls each operation mechanism provided in the chamber 6 and the light irradiation unit 5 to execute the heat treatment of the semiconductor wafer W.

  The chamber 6 is provided below the light irradiation unit 5 and includes a chamber side portion 63 having a substantially cylindrical inner wall and a chamber bottom portion 62 that covers a lower portion of the chamber side portion 63. A space surrounded by the chamber side 63 and the chamber bottom 62 is defined as a heat treatment space 65. An upper opening 60 is formed above the heat treatment space 65, and a chamber window 61 is attached to the upper opening 60 to be closed.

  The chamber window 61 constituting the ceiling portion of the chamber 6 is a disk-shaped member made of quartz, and transmits the flash light emitted from the light irradiation unit 5 to the heat treatment space 65. The chamber bottom 62 and the chamber side 63 constituting the main body of the chamber 6 are formed of, for example, a metal material having excellent strength and heat resistance such as stainless steel, and a ring on the upper side of the inner side surface of the chamber side 63. 631 is formed of an aluminum (Al) alloy or the like having durability superior to stainless steel against deterioration due to light irradiation.

  Further, in order to maintain the airtightness of the heat treatment space 65, the chamber window 61 and the chamber side portion 63 are sealed by an O-ring. That is, the O-ring is sandwiched between the lower surface peripheral portion of the chamber window 61 and the chamber side portion 63, the clamp ring 90 is brought into contact with the upper peripheral portion of the chamber window 61, and the clamp ring 90 is attached to the chamber side portion 63. The chamber window 61 is pressed against the O-ring by screwing.

  The chamber bottom 62 has a plurality of (this embodiment) for supporting the semiconductor wafer W from the lower surface (surface opposite to the side irradiated with light from the light irradiation unit 5) through the holding unit 7. Then, three support pins 70 are erected. The support pin 70 is made of, for example, quartz and is fixed from the outside of the chamber 6 and can be easily replaced.

The chamber side 63 has a transfer opening 66 for carrying in and out the semiconductor wafer W, and the transfer opening 66 can be opened and closed by a gate valve 185 that rotates about a shaft 662. A portion of the chamber side 63 opposite to the transfer opening 66 is provided with a processing gas (for example, an inert gas such as nitrogen (N ₂ ) gas, helium (He) gas, argon (Ar) gas) in the heat treatment space 65, Alternatively, an introduction path 81 for introducing oxygen (0 ₂ ) gas or the like is formed, one end of which is connected to an air supply mechanism (not shown) via a valve 82, and the other end is formed inside the chamber side portion 63. Connected to the gas introduction buffer 83. A discharge passage 86 for discharging the gas in the heat treatment space 65 is formed in the transfer opening 66 and is connected to an exhaust mechanism (not shown) through a valve 87.

  FIG. 2 is a cross-sectional view of the chamber 6 cut along a horizontal plane at the position of the gas introduction buffer 83. As shown in FIG. 2, the gas introduction buffer 83 is formed over about ３ of the inner periphery of the chamber side 63 on the opposite side of the transfer opening 66 shown in FIG. Then, the processing gas guided to the gas introduction buffer 83 is supplied into the heat treatment space 65 from the plurality of gas supply holes 84.

  The heat treatment apparatus 1 also includes a substantially disc-shaped holding unit 7 that holds the semiconductor wafer W in a horizontal position inside the chamber 6 and performs preheating of the held semiconductor wafer W before irradiation with flash light. And a holding unit elevating mechanism 4 that elevates the unit 7 with respect to the chamber bottom 62 which is the bottom surface of the chamber 6. 1 includes a substantially cylindrical shaft 41, a moving plate 42, guide members 43 (three arranged around the shaft 41 in the present embodiment), a fixed plate 44, a ball screw 45, It has a nut 46 and a motor 40. A substantially circular lower opening 64 having a smaller diameter than the holding portion 7 is formed in the chamber bottom 62 which is the lower portion of the chamber 6, and the stainless steel shaft 41 is inserted through the lower opening 64 to hold the holding portion. 7 (strictly speaking, the hot plate 71 of the holding unit 7) is connected to the lower surface of the holding unit 7 to support it.

  A nut 46 that is screwed into the ball screw 45 is fixed to the moving plate 42. The moving plate 42 is slidably guided by a guide member 43 that is fixed to the chamber bottom 62 and extends downward, and is movable in the vertical direction. Further, the moving plate 42 is connected to the holding unit 7 via the shaft 41.

  The motor 40 is installed on a fixed plate 44 attached to the lower end of the guide member 43, and is connected to the ball screw 45 via the timing belt 401. When the holding part 7 is raised and lowered by the holding part raising / lowering mechanism 4, the motor 40 as the driving part rotates the ball screw 45 under the control of the control part 3, and the moving plate 42 to which the nut 46 is fixed follows the guide member 43. Move vertically. As a result, the shaft 41 fixed to the moving plate 42 moves along the vertical direction, and the holding unit 7 connected to the shaft 41 moves between the delivery position of the semiconductor wafer W shown in FIG. 1 and the semiconductor wafer W shown in FIG. Move up and down smoothly between the processing positions.

  On the upper surface of the moving plate 42, a mechanical stopper 451 having a substantially semi-cylindrical shape (a shape obtained by cutting the cylinder in half along the longitudinal direction) is provided so as to extend along the ball screw 45. If the upper limit of the mechanical stopper 451 is struck against the end plate 452 provided at the end of the ball screw 45, the moving plate 42 is prevented from rising abnormally. Thereby, the holding part 7 does not rise above a predetermined position below the chamber window 61, and the collision between the holding part 7 and the chamber window 61 is prevented.

  The holding unit lifting mechanism 4 has a manual lifting unit 49 that manually lifts and lowers the holding unit 7 when performing maintenance inside the chamber 6. The manual elevating part 49 has a handle 491 and a rotating shaft 492. By rotating the rotating shaft 492 via the handle 491, the ball screw 45 connected to the rotating shaft 492 is rotated via the timing belt 495 to hold the holding part. 7 can be moved up and down.

  A telescopic bellows 47 that surrounds the shaft 41 and extends downward is provided below the chamber bottom 62, and its upper end is connected to the lower surface of the chamber bottom 62. On the other hand, the lower end of the bellows 47 is attached to the bellows lower end plate 471. The bellows lower end plate 471 is attached by being screwed to the shaft 41 by a flange-shaped member 411. The bellows 47 is contracted when the holding portion 7 is raised with respect to the chamber bottom 62 by the holding portion lifting mechanism 4, and the bellows 47 is expanded when the holding portion 7 is lowered. When the holding unit 7 moves up and down, the airtight state in the heat treatment space 65 is maintained by the expansion and contraction of the bellows 47.

  FIG. 3 is a cross-sectional view showing the configuration of the holding unit 7. The holding unit 7 is installed on a hot plate (heating plate) 71 that preheats the semiconductor wafer W (so-called assist heating), and an upper surface of the hot plate 71 (a surface on the side where the holding unit 7 holds the semiconductor wafer W). The susceptor 72 is provided. As described above, the shaft 41 that moves up and down the holding unit 7 is connected to the lower surface of the holding unit 7. The susceptor 72 is made of quartz (or may be aluminum nitride (AIN) or the like), and a pin 75 for preventing displacement of the semiconductor wafer W is provided on the upper surface thereof. The susceptor 72 is installed on the hot plate 71 with its lower surface in surface contact with the upper surface of the hot plate 71. Thus, the susceptor 72 diffuses the thermal energy from the hot plate 71 and transmits it to the semiconductor wafer W placed on the upper surface of the susceptor 72, and can be removed from the hot plate 71 and cleaned during maintenance.

  The hot plate 71 includes an upper plate 73 and a lower plate 74 made of stainless steel. A resistance heating wire 76 such as a nichrome wire for heating the hot plate 71 is disposed between the upper plate 73 and the lower plate 74, and is filled with a conductive nickel (Ni) solder and sealed. The end portions of the upper plate 73 and the lower plate 74 are bonded by brazing.

  FIG. 4 is a plan view showing the hot plate 71. As shown in FIG. 4, the hot plate 71 includes a disc-shaped zone 711 and an annular zone 712 that are concentrically arranged in the center of a region facing the held semiconductor wafer W, and the zone 712. There are four zones 713 to 716 obtained by equally dividing a peripheral substantially annular region into four equal parts in the circumferential direction, and a slight gap is formed between the zones. The hot plate 71 is provided with three through holes 77 through which the support pins 70 are inserted, every 120 ° on the circumference of the gap between the zone 711 and the zone 712.

  In each of the six zones 711 to 716, heaters are individually formed so that mutually independent resistance heating wires 76 circulate, and each zone is individually formed by a heater built in each zone. Heated. The semiconductor wafer W held by the holding unit 7 is heated by heaters built in the six zones 711 to 716. Each of the zones 711 to 716 is provided with a sensor 710 that measures the temperature of each zone using a thermocouple. Each sensor 710 passes through the inside of a substantially cylindrical shaft 41 and is connected to the control unit 3.

  When the hot plate 71 is heated, the resistance heating wire disposed in each zone is set so that the temperature of each of the six zones 711 to 716 measured by the sensor 710 becomes a predetermined temperature. The amount of power supplied to 76 is controlled by the control unit 3. The temperature control of each zone by the control unit 3 is performed by PID (Proportional, Integral, Derivative) control. In the hot plate 71, the temperature of each of the zones 711 to 716 is continuously measured until the heat treatment of the semiconductor wafer W (when plural semiconductor wafers W are continuously processed, the heat treatment of all the semiconductor wafers W) is completed. Then, the power supply amount to the resistance heating wire 76 disposed in each zone is individually controlled, that is, the temperature of the heater built in each zone is individually controlled, and the temperature of each zone becomes the set temperature. Maintained. The set temperature of each zone can be changed by an offset value set individually from the reference temperature.

  The resistance heating wires 76 respectively disposed in the six zones 711 to 716 are connected to a power supply source (not shown) via a power line passing through the inside of the shaft 41. On the way from the power supply source to each zone, the power lines from the power supply source are arranged so as to be electrically insulated from each other inside a stainless tube filled with an insulator such as magnesia (magnesium oxide). The The interior of the shaft 41 is open to the atmosphere.

  Next, the light irradiation unit 5 is configured by arranging a plurality of (30 in the present embodiment) xenon flash lamps FL inside a liquid tank 51 having a liquid-tight structure. Further, the light irradiation unit 5 includes a chiller 55 that circulates and supplies the coolant to the liquid tank 51.

  FIG. 6 is a plan view of the liquid tank 51 for illustrating the arrangement configuration of the flash lamp FL. 7 is a cross-sectional view taken along the line II of FIG. 6, and FIG. 8 is a cross-sectional view taken along the line II-II of FIG. The liquid tank 51 is a casing capable of storing liquid therein, and is installed above the chamber 6. The tank bottom 51a and the tank side 51b of the liquid tank 51 are formed of quartz that can transmit flash light. The tank bottom 51a of the liquid tank 51 functions as a lamp light radiation window that transmits flash light. By installing the liquid tank 51 above the chamber 6, the tank bottom 51 a faces the chamber window 61. The light irradiation unit 5 heats the semiconductor wafer W by irradiating the semiconductor wafer W held by the holding unit 7 in the chamber 6 with flash light from the flash lamp FL via the tank bottom 51 a and the chamber window 61.

  A reflector 52 is mounted on the ceiling of the liquid tank 51. The reflector 52 is provided above the plurality of flash lamps FL so as to cover all of them, and also functions as a lid of the liquid tank 51. The basic function of the reflector 52 is to reflect flash light emitted from the plurality of flash lamps FL toward the holding unit 7. The reflector 52 is formed of an aluminum alloy plate, and the surface (the surface facing the flash lamp FL) is roughened by blasting to exhibit a satin pattern. The roughening process is performed when the surface of the reflector 52 is a perfect mirror surface, and a regular pattern is generated in the intensity of the reflected light from the plurality of flash lamps FL, so that the surface temperature distribution of the semiconductor wafer W is obtained. This is because the uniformity of the is reduced.

  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). The liquid tanks 51 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. Each xenon flash lamp FL is configured by sealing a xenon gas inside a rod-shaped glass tube (discharge tube) 91 and disposing an anode (anode) 92 and a cathode (cathode) 93 at both inner ends thereof. The anode 92 and the cathode 93 are connected to a capacitor (not shown) to which a predetermined voltage can be applied by a power supply unit.

  A trigger electrode 94 is provided near the outer peripheral surface of the glass tube 91 between adjacent flash lamps FL. The trigger electrode 94 has a tungsten (W) wire disposed in the axial center of a quartz glass thin tube. Since xenon gas is an electrical insulator, electricity does not flow into the glass tube 91 in a normal state even if charges are accumulated in the capacitor. However, when the insulation is broken by applying a high voltage to the trigger electrode 94, a discharge is generated between the anode 92 and the cathode 93, and the electricity stored in the capacitor flows instantaneously into the glass tube 91. When the xenon gas is heated by Joule heat, light is emitted. In such a xenon flash lamp FL, the electrostatic energy stored in the capacitor 93 in advance is converted into an extremely short light pulse of 0.1 to 10 milliseconds, so that compared to a continuously lit light source. It has the feature that it can irradiate extremely strong light.

  As shown in FIG. 6, in the present embodiment, 30 flash lamps FL are arranged in the liquid tank 51 with the anode-cathode directions aligned. That is, all thirty flash lamps FL are arranged so that the anode 92 is located on the left side of FIG. 6 and the cathode 93 is located on the right side of the page. In the present embodiment, the outer diameter of the glass tube 91 is 13 mm, and the interval between adjacent glass tubes 91 is 2 mm.

  Each flash lamp FL is horizontally mounted on the opposite tank side portions 51 b of the liquid tank 51. That is, 30 pairs of through holes are formed in opposite tank side parts 51b of the liquid tank 51, and both flash lamps FL are disposed by fitting both ends of the glass tube 91 into the through holes. Yes. Power lines for supplying power to the flash lamp FL are connected to both ends of the glass tube 91 protruding to the outside of the liquid tank 51, and further connected to the anode 92 and the cathode 93 through the inside of the glass tube 91.

  FIG. 9 is an enlarged view of the vicinity of the fitting portion of the glass tube 91. O-rings 53 are attached to the outer peripheral surfaces of both ends of the glass tube 91 of each flash lamp FL. The O-ring 53 is in close contact with the outer peripheral surface of the glass tube 91 and the tank side portion 51b by a pressing member 54. As a result, the O-ring 53 functions as a seal member for a portion where the flash lamp FL is fitted into the tank side portion 51b.

  Although the liquid leakage from the liquid tank 51 should be prevented by the O-ring 53, in the unlikely event that a liquid leakage occurs, the outside of the liquid tank 51 receives the coolant leaked from the liquid tank 51. A tank 56 is provided. Further, the outer tank 56 is provided with a leak detection unit 57 that detects that the coolant has flowed in. The leak detection unit 57 detects the coolant flowing into a detection hole formed in a part of the bottom of the outer tub 56 and transmits a leak detection signal to the control unit 3. Since the liquid leakage from the wall surface parallel to the flash lamp FL in the tank side portion 51b of the liquid tank 51 cannot occur, the outer tank 56 is provided only outside the wall surface through which both ends of the flash lamp FL are fitted. It has been. In addition, the leak detection unit 57 is not limited to a mode for detecting the coolant flowing into the detection hole, and various known liquid leak sensors such as a sensor for optically detecting the liquid level can be used.

  The chiller 55 circulates and supplies the cooling liquid to the liquid tank 51, and cools the cooling liquid to maintain it at a predetermined temperature. In this embodiment, pure water is used as the coolant. The chiller 55 supplies the cooling liquid cooled to a predetermined temperature from the cathode 93 side of the flash lamp FL to the liquid tank 51 and collects the cooling liquid from the anode 92 side. Thereby, the inside of the liquid tank 51 is filled with the cooling liquid, and all of the 30 flash lamps FL are immersed in the cooling liquid. Further, in the liquid tank 51, a cooling liquid flow is formed from the cathode 93 side of the flash lamp FL toward the anode 92. The cooling liquid discharged and collected from the liquid tank 51 is cooled again to a predetermined temperature by the chiller 55 and supplied to the liquid tank 51 again.

  The control unit 3 controls various operation mechanisms such as the chiller 55 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.

  Next, a processing procedure of the semiconductor wafer W in the heat treatment apparatus 1 will be briefly described. Here, the semiconductor wafer W to be processed is a semiconductor substrate to which an impurity (ion) is added by an ion implantation method, and the activation of the added impurity is performed by a flash heating process by the heat treatment apparatus 1.

  First, the holding unit 7 is lowered from the processing position shown in FIG. 5 to the delivery position shown in FIG. The “processing position” is a position of the holding unit 7 when the semiconductor wafer W is irradiated with flash light from the flash lamp FL, and is a position in the chamber 6 of the holding unit 7 shown in FIG. Further, the “delivery position” is the position of the holding unit 7 when the semiconductor wafer W is carried in and out of the chamber 6, and is the position of the holding unit 7 shown in FIG. The reference position of the holding unit 7 in the heat treatment apparatus 1 is the processing position. Before the processing, the holding unit 7 is located at the processing position, and this is lowered to the delivery position at the start of processing. As shown in FIG. 1, when the holding portion 7 is lowered to the delivery position, the holding portion 7 comes close to the chamber bottom portion 62, and the tip of the support pin 70 penetrates the holding portion 7 and protrudes above the holding portion 7.

  Next, when the holding unit 7 is lowered to the delivery position, the valve 82 and the valve 87 are opened, and normal temperature nitrogen gas is introduced into the heat treatment space 65 of the chamber 6. Subsequently, the gate valve 185 is opened to open the transfer opening 66, and the semiconductor wafer W after ion implantation is transferred into the chamber 6 through the transfer opening 66 by a transfer robot outside the apparatus, and a plurality of support pins 70. Placed on top.

  The purge amount of nitrogen gas into the chamber 6 when the semiconductor wafer W is loaded is about 40 liters / minute, and the supplied nitrogen gas is moved from the gas introduction buffer 83 in the direction of the arrow AR4 shown in FIG. Then, the exhaust gas is exhausted by utility exhaust via the discharge path 86 and the valve 87 shown in FIG. A part of the nitrogen gas supplied to the chamber 6 is also discharged from an outlet (not shown) provided inside the bellows 47. In each step described below, nitrogen gas is continuously supplied to and exhausted from the chamber 6, and the supply amount of the nitrogen gas is variously changed according to the processing process of the semiconductor wafer W.

  When the semiconductor wafer W is loaded into the chamber 6, the transfer opening 66 is closed by the gate valve 185. The holding unit lifting mechanism 4 raises the holding unit 7 from the delivery position to a processing position close to the chamber window 61. In the process in which the holding unit 7 is lifted from the delivery position, the semiconductor wafer W is transferred from the support pins 70 to the susceptor 72 of the holding unit 7 and placed and held on the upper surface of the susceptor 72. When the holding unit 7 is raised to the processing position, the semiconductor wafer W held by the susceptor 72 is also held at the processing position.

  Each of the six zones 711 to 716 of the hot plate 71 is heated to a predetermined temperature by a heater (resistive heating wire 76) individually incorporated in each zone (between the upper plate 73 and the lower plate 74). ing. When the holding unit 7 rises to the processing position and the semiconductor wafer W comes into contact with the holding unit 7, the semiconductor wafer W is preheated by the heater built in the hot plate 71 and the temperature gradually rises.

  Preheating for about 60 seconds is performed at this processing position, and the temperature of the semiconductor wafer W rises to a preset preheating temperature T1. The preheating temperature T1 is set to about 200 ° C. to 800 ° C., preferably about 350 ° C. to 550 ° C., in which impurities added to the semiconductor wafer W are not likely to diffuse due to heat. Further, the distance between the holding unit 7 and the chamber window 61 can be arbitrarily adjusted by controlling the rotation amount of the motor 40 of the holding unit lifting mechanism 4.

  After the preheating time of about 60 seconds elapses, flash light is irradiated from the flash lamp FL of the light irradiation unit 5 toward the semiconductor wafer W under the control of the control unit 3 while the holding unit 7 is positioned at the processing position. At this time, a part of the flash light emitted from the flash lamp FL goes directly to the holding part 7 in 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 of the flash light. Since the flash heating is performed by flash irradiation from the flash lamp FL, the surface temperature of the semiconductor wafer W can be increased in a short time.

  That is, the flash light irradiated from the flash lamp FL of the light irradiation unit 5 has an irradiation time of about 0.1 to 10 milliseconds, in which the electrostatic energy stored in advance is converted into an extremely short light pulse. It is a very short and strong flash. Then, the surface temperature of the semiconductor wafer W flash-heated by flash irradiation from the flash lamp FL instantaneously rises to a processing temperature T2 of about 1000 ° C. to 1100 ° C., and the impurities added to the semiconductor wafer W are activated. After being done, the surface temperature drops rapidly. As described above, in the heat treatment apparatus 1, the surface temperature of the semiconductor wafer W can be raised and lowered in a very short time. Therefore, diffusion of impurities added to the semiconductor wafer W due to heat (this diffusion phenomenon is caused in the semiconductor wafer W). It is possible to activate the impurities while suppressing the impurity profile. Since the time required for activation of the added impurity is extremely short compared to the time required for thermal diffusion, activation is possible even for a short time when no diffusion of about 0.1 millisecond to 10 millisecond occurs. Is completed.

  In addition, by preheating the semiconductor wafer W by the holding unit 7 before the flash heating, the surface temperature of the semiconductor wafer W can be quickly raised to the processing temperature T2 by flash irradiation from the flash lamp FL.

  After the flash heating is finished and the standby for about 10 seconds at the processing position, the holding unit 7 is lowered again to the delivery position shown in FIG. 1 by the holding unit lifting mechanism 4, and the semiconductor wafer W is transferred from the holding unit 7 to the support pins 70. Is passed. Subsequently, the transfer opening 66 closed by the gate valve 185 is opened, and the semiconductor wafer W placed on the support pins 70 is unloaded by a transfer robot outside the apparatus, and the semiconductor wafer W is flushed in the heat treatment apparatus 1. The heat treatment is completed.

  As described above, nitrogen gas is continuously supplied to the chamber 6 during the heat treatment of the semiconductor wafer W in the heat treatment apparatus 1, and the supply amount is about 30 liters / minute when the holding unit 7 is located at the processing position. When the holding unit 7 is located at a position other than the processing position, the rate is about 40 liters / minute.

  By the way, in the present embodiment, a plurality of flash lamps FL are accommodated in the liquid tank 51, and a cooling liquid (pure water in the present embodiment) is circulated and supplied from the chiller 55 to the liquid tank 51. When the semiconductor wafer W is being processed in the heat treatment apparatus 1, the circulating supply of the cooling liquid is continuously performed, and the liquid tank 51 is filled with the cooling liquid. Therefore, when the plurality of flash lamps FL emit flash light during the flash heating, the plurality of flash lamps FL are immersed in the coolant supplied from the chiller 55 to the liquid tank 51.

  When the flash lamp FL emits flash light, a discharge occurs between the anode 92 and the cathode 93 and the inner wall of the glass tube 91 is exposed to high-temperature plasma, but the outer wall of the glass tube 91 is immersed in the cooling liquid. Therefore, the temperature rise of the glass tube 91 as a whole is suppressed by liquid cooling. As a result, the life deterioration of the flash lamp FL can be suppressed. In particular, in the case where 30 flash lamps FL are provided as in the heat treatment apparatus 1 of the present embodiment, the increase in running cost due to the lamp life is suppressed by suppressing the life deterioration of each flash lamp FL. can do.

  Further, if the temperature rise of the glass tube 91 can be suppressed, it becomes possible to supply a larger electric power to the flash lamp FL than before, and the width of the energy of flash light that can be irradiated can be widened. The variation of can be made richer.

  Even if one of the flash lamps FL bursts, the cooling liquid becomes a buffer material and the impact of the burst is greatly reduced, so that adjacent flash lamps FL are severely damaged one after another. Things can be avoided.

  In the present embodiment, 30 flash lamps FL are arranged in the liquid tank 51 with the anode-cathode directions aligned. Of the electrodes at both ends of the flash lamp FL, the cathode 93 is grounded (ground level). Therefore, it is the anode 92 side that requires measures such as prevention of electric shock. If the flash lamps FL can be arranged in a line with the anode-cathode orientation aligned as in this embodiment, one side of the liquid tank 51 (FIG. 6). Then, it is convenient to take measures only on the left side of the page).

  However, when flash light irradiation is performed with the flash lamps FL aligned with the anode-cathode orientation aligned, a strong attractive force is instantaneously generated between adjacent flash lamps FL, and liquid is supplied as in the past. If the flash lamps FL are disposed without doing so, the glass tubes 91 of the adjacent flash lamps FL may collide and be damaged. For this reason, conventionally, a plurality of flash lamps FL are arranged so that the anode-cathode directions are staggered. However, such an arrangement complicates measures such as prevention of electric shock. In the present embodiment, since flash light irradiation is performed in a state where a plurality of flash lamps FL are immersed in a cooling liquid, even if a strong attractive force is generated instantaneously, the rapid movement of the glass tube 91 is mitigated. Since breakage due to the collision of the glass tube 91 can be prevented, 30 flash lamps FL can be arranged in the liquid tank 51 with the anode-cathode direction aligned, and as a result, measures such as prevention of electric shock are easy. It becomes.

  In the state where 30 flash lamps FL are arranged in the liquid tank 51 with the anode-cathode directions aligned, the chiller 55 supplies the cooling liquid from the cathode 93 side of the flash lamp FL and Collected from the side. That is, the cathode 93 of the flash lamp FL is located in the liquid tank 51 on the upstream side of the coolant. At the time of flash light irradiation, the cathode 93 side tends to be hotter than the anode 92. If the coolant is allowed to flow from the cathode 93 of the flash lamp FL toward the anode 92 as in the present embodiment, the cooling performance is higher on the cathode 93 side, which tends to be high in temperature, and appropriate cooling of the flash lamp FL is achieved. Can be performed.

  Furthermore, since the heat treatment apparatus 1 of the present embodiment includes the outer tank 56 provided with the leak detection unit 57, even if a liquid leak occurs from the liquid tank 51, the leaked liquid is recovered. In addition, it is possible to detect liquid leakage immediately.

  While the embodiments of the present invention have been described above, the present invention can be modified in various ways other than those described above without departing from the spirit of the present invention. For example, in each of the above embodiments, pure water is used as the cooling liquid, but the present invention is not limited to this, and other liquids such as fluorocarbon may be used. The cooling liquid is preferably a liquid having a large specific heat.

  Further, a shower nozzle may be provided in the liquid tank 51, and the coolant may be sprayed on the flash lamp FL as a mist. However, when the cooling liquid is sprayed as mist, the cooling effect of the flash lamp FL is obtained, but it does not function as a buffer material to prevent the flash lamp FL from being damaged. Therefore, the cooling liquid is used as a fluid as in the above embodiment. It is preferable to supply the liquid tank 51 and immerse a plurality of flash lamps FL in the cooling liquid.

  In the above embodiment, the trigger electrode 94 is provided between the adjacent flash lamps FL. However, the trigger electrode 94 may be provided immediately above each of the plurality of flash lamps FL.

  In the above embodiment, the light irradiation unit 5 is provided with 30 flash lamps FL. However, the present invention is not limited to this, and the number of flash lamps FL can be any number. . The flash lamp FL is not limited to a xenon flash lamp, and may be a krypton flash lamp.

  In the above embodiment, the semiconductor wafer is irradiated with light to perform the ion activation process. However, the substrate to be processed by the heat treatment apparatus according to the present invention is not limited to the semiconductor wafer. . For example, the glass substrate on which various silicon films such as a silicon nitride film and a polycrystalline silicon film are formed may be processed by the heat treatment apparatus according to the present invention. As an example, an amorphous silicon film made amorphous by ion implantation of silicon into a polycrystalline silicon film formed on a glass substrate by a CVD method is formed, and a silicon oxide film serving as an antireflection film is further formed thereon. Form. In this state, the entire surface of the amorphous silicon film is irradiated with light by the heat treatment apparatus according to the present invention, so that a polycrystalline silicon film obtained by polycrystallizing the amorphous silicon film can be formed.

  Further, a heat treatment according to the present invention is applied to a TFT substrate having a structure in which a base silicon oxide film and a polysilicon film obtained by crystallizing amorphous silicon are formed on a glass substrate, and the polysilicon film is doped with impurities such as phosphorus and boron. It is also possible to activate the impurities implanted in the doping process by irradiating light with an apparatus.

It is a sectional side view which shows the structure of the heat processing apparatus which concerns on this invention. It is sectional drawing which shows the gas path of the heat processing apparatus of FIG. It is sectional drawing which shows the structure of a holding | maintenance part. It is a top view which shows a hot plate. It is a sectional side view which shows the structure of the heat processing apparatus of FIG. It is a top view of the liquid tank for showing the arrangement configuration of a flash lamp. It is the II sectional view taken on the line of FIG. It is the II-II sectional view taken on the line of FIG. It is the figure which expanded the vicinity of the fitting part of a glass tube.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat processing apparatus 4 Holding part raising / lowering mechanism 5 Light irradiation part 6 Chamber 7 Holding part 51 Liquid tank 51a Tank bottom part 51b Tank side part 52 Reflector 53 O-ring 55 Chiller 56 Outer tank 57 Leak detection part 61 Chamber window 65 Heat treatment space 71 Hot plate 72 Susceptor 91 Glass tube 92 Anode 93 Cathode 94 Trigger electrode FL Flash lamp W Semiconductor wafer

Claims (3)

A heat treatment apparatus for heating a substrate by irradiating the substrate with flash light,
A chamber with a chamber window at the top for transmitting flash light;
Holding means for holding the substrate in a horizontal position in the chamber;
A liquid tank disposed above the chamber and having a radiation window that transmits flash light at the bottom;
A plurality of flash lamps arranged in the liquid tank and emitting flash light by discharging between the anode and the cathode in a rod-shaped discharge tube;
A coolant supply means for supplying a coolant to the liquid tank;
With
When the plurality of flash lamps emit flash light, the plurality of flash lamps are immersed in the coolant supplied from the coolant supply means to the liquid tank. The heat treatment apparatus according to claim 1, wherein
The plurality of flash lamps are aligned in a horizontal direction in the liquid tank with the anode-cathode orientation aligned,
The heat treatment apparatus, wherein the coolant supply means supplies coolant from the cathode side of the plurality of flash lamps. In the heat treatment apparatus according to claim 1 or 2,
An outer tank for receiving the coolant leaked from the liquid tank;
Leakage detection means for detecting that the coolant has flowed into the outer tub,
A heat treatment apparatus further comprising:

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