JP4879003B2 - Heat treatment equipment - Google Patents

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, the surface of the semiconductor wafer is irradiated with flash light (flash light) using a xenon flash lamp, so that only the surface of the semiconductor wafer into which ions are implanted is heated in an extremely short time (a few milliseconds or less). Techniques have been proposed (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

  By the way, a heat treatment apparatus that performs flash heating is often provided with a hot plate that preheats a semiconductor wafer before irradiation with flash light. This is because if the surface of the semiconductor wafer is heated to 1000 ° C. or higher only by flash light irradiation, the flash light of very large energy must be irradiated, and only the wafer surface is heated suddenly. Because there is a risk of cracking, the semiconductor wafer is placed on a hot plate, preheated to about 500 ° C., and then irradiated with flash light from a xenon flash lamp to reach a predetermined annealing temperature. is there.

  However, a relatively long wavelength infrared ray corresponding to the temperature is emitted from such a hot plate, and the discharge tube (made of quartz) of the xenon flash lamp is heated from the outside by the radiant heat. When the xenon flash lamp is heated by radiant heat from a hot plate with a relatively high temperature of 500 ° C or higher, the xenon flash lamp cannot be sufficiently cooled only by the air supply / exhaust described above, and the discharge tube is discolored. There is a problem that the lamp life is shortened or the xenon flash lamp deteriorates rapidly and bursts in the worst case. For this reason, conventionally, the upper limit of the preheating temperature by the hot plate is restricted, and the processing conditions for the annealing treatment of the semiconductor wafer have to be limited.

  This invention is made | formed in view of the said subject, and it aims at providing the heat processing apparatus which can cool a flash lamp effectively.

In order to solve the above-mentioned problem, the invention of claim 1 is directed to a heat treatment apparatus for heating a substrate by irradiating flash light onto the substrate, a holding unit for holding the substrate, and the holding unit from a rod-shaped discharge tube. A flash lamp that emits flash light toward the substrate held in the substrate, a buffer space, and a gas storage portion that has an ejection hole that communicates with the buffer space and faces the flash lamp; and A gas supply for supplying a gas to the buffer space so that the atmospheric pressure is approximately twice or more the atmospheric pressure around the gas storage section and blowing a gas having a transonic or higher flow velocity from the ejection hole toward the flash lamp. And means.

  According to a second aspect of the present invention, in the heat treatment apparatus according to the first aspect of the present invention, the diameter of the ejection hole is from 0.5 mm to 1.5 mm.

According to a third aspect of the present invention, in a heat treatment apparatus for heating a substrate by irradiating the substrate with flash light, a holding unit for holding the substrate and a substrate held by the holding unit from a rod-shaped discharge tube A light source having a plurality of flash lamps that emit flash light toward the head, a buffer space, and a gas storage unit having a plurality of ejection holes that communicate with the buffer space and go to the light source, A gas having a flow velocity equal to or higher than a transonic speed from the plurality of ejection holes toward the light source by supplying a gas so that the pressure in the buffer space is approximately twice or more than the pressure around the gas reservoir. And a gas supply means for spraying .

  According to a fourth aspect of the present invention, in the heat treatment apparatus according to the third aspect of the present invention, each of the plurality of ejection holes is provided in the gas storage section so as to eject a gas toward one of the plurality of flash lamps. It is formed.

  The invention according to claim 5 is the heat treatment apparatus according to claim 3, wherein each of the plurality of ejection holes ejects gas toward a gap between the lamps in the array of the plurality of flash lamps. It is formed in the gas storage part.

  The invention of claim 6 is the heat treatment apparatus according to any one of claims 3 to 5, wherein each of the plurality of ejection holes has a diameter of 0.5 mm or more and 1.5 mm or less. And

  According to a seventh aspect of the present invention, in the heat treatment apparatus according to any one of the third to sixth aspects, the holding unit includes a preheating mechanism that preheats the substrate held before the flash light irradiation. It is characterized by that.

  According to an eighth aspect of the present invention, in a heat treatment apparatus for heating a substrate by irradiating the substrate with flash light, a holding unit for holding the substrate and a substrate held by the holding unit from a rod-shaped discharge tube A flash lamp that emits flash light toward the flash lamp, and a gas ejection portion that blows a gas having a flow velocity of transonic or higher toward the flash lamp.

  According to the first and second aspects of the present invention, the gas is supplied to the buffer space so that the air pressure in the buffer space is approximately twice or more the air pressure around the gas storage portion. As a result, a gas flow having a flow velocity higher than the transonic speed is ejected as a turbulent flow, and the flash lamp can be effectively cooled.

  According to the third to seventh aspects of the present invention, since the gas is supplied to the buffer space so that the atmospheric pressure in the buffer space is approximately twice or more the atmospheric pressure around the gas storage portion, the light source is emitted from the ejection hole. As a result, a gas flow at a transonic speed or higher is ejected as a turbulent flow, and the flash lamp can be effectively cooled.

  In particular, according to the invention of claim 4, since the gas is ejected from each of the plurality of ejection holes toward one of the plurality of flash lamps, the flash lamp can be cooled more effectively.

  In particular, according to the invention of claim 5, gas is ejected from each of the plurality of ejection holes toward the gaps between the lamps in the arrangement of the plurality of flash lamps. The flash lamp can be cooled, and the total number of ejection holes can be reduced to easily form a gas flow having a flow velocity higher than transonic speed.

  According to the invention of claim 8, since a gas having a transonic speed or higher is blown toward the flash lamp, a turbulent flow is formed around the flash lamp, and the flash lamp is effectively cooled. Can do.

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

<1. First Embodiment>
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 lamp house 5 that houses a plurality of flash lamps 69. Further, the heat treatment apparatus 1 includes a control unit 3 that controls each operation mechanism provided in the chamber 6 and the lamp house 5 to execute the heat treatment of the semiconductor wafer W.

  The chamber 6 is provided below the lamp house 5 and includes a chamber side 63 having a substantially cylindrical inner wall and a chamber bottom 62 covering the lower part of the chamber side 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 light emitted from the lamp house 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 (in this embodiment) for supporting the semiconductor wafer W from the lower surface (surface opposite to the side irradiated with light from the lamp house 5) through the holding portion 7. 3) support pins 70 are provided upright. 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. In a portion of the chamber side 63 opposite to the transfer opening 66, an inert gas such as nitrogen (N ₂ ) gas, helium (He) gas, argon (Ar) gas, etc. 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 disk-shaped holding unit 7 that holds the semiconductor wafer W inside the chamber 6 and performs preheating of the semiconductor wafer W held before the flash light irradiation, and the holding unit 7 in the chamber 6. And a holding unit elevating mechanism 4 that elevates and lowers with respect to the chamber bottom 62 which is the bottom surface of 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 portion 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.

  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. Between the upper plate 73 and the lower plate 74, a resistance heating wire such as a nichrome wire for heating the hot plate 71 is disposed and 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. 3 is a plan view showing the hot plate 71. As shown in FIG. 3, the hot plate 71 includes a disk-shaped zone 711 and an annular zone 712 that are concentrically arranged in the center of a region facing the semiconductor wafer W to be held, 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 formed so that mutually independent resistance heating wires circulate, and each zone is individually heated by a heater built in each zone. . 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 control unit 3 controls the amount of power supplied to the. 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. The amount of power supplied to the resistance heating wires arranged 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 is maintained at the set temperature. Is done. The set temperature of each zone can be changed by an offset value set individually from the reference temperature.

  The resistance heating wires 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 lamp house 5 will be described. The lamp house 5 covers a light source including a plurality of (30 in the present embodiment) xenon flash lamps (hereinafter simply referred to as “flash lamps”) 69 inside the housing 51 and the light source. The reflector 52 is provided, and the cooling box 20 disposed above the reflector 52 is configured. A lamp light emission window 53 is attached to the bottom of the casing 51 of the lamp house 5. The lamp light radiation window 53 constituting the floor of the lamp house 5 is a plate-like member made of quartz. By installing the lamp house 5 above the chamber 6, the lamp light emission window 53 faces the chamber window 61. The lamp house 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 69 via the lamp light emission window 53 and the chamber window 61. .

  Each of the plurality of flash lamps 69 is a rod-shaped lamp having a long cylindrical shape, and the longitudinal direction of each of the flash lamps 69 is along the main surface of the semiconductor wafer W held by the holding unit 7 (along the horizontal direction). They are arranged in a plane so as to be parallel. The flash lamp 69 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 is wound on the outer peripheral surface of the glass tube. And a triggered electrode. Since xenon gas is an electrical insulator, electricity does not flow in the discharge tube under normal conditions. However, when insulation is broken by applying a high voltage to the trigger electrode, the electricity stored in the capacitor flows instantaneously into the discharge tube, and the xenon gas is heated by Joule heat at that time, and light is emitted. . In the flash lamp 69, the electrostatic energy stored in advance is converted into an extremely short light pulse of 0.1 to 10 milliseconds, so that it emits extremely strong light as compared with a continuous light source. It has the feature of obtaining. In addition, the diameter of the discharge tube of each flash lamp 69 of this embodiment is about 13 mm, and the gap between adjacent flash lamps 69 in the lamp array is about 2 mm.

  FIG. 5 is a diagram schematically showing the configuration of the cooling box 20. The cooling box 20 is a box-shaped member having a rectangular shape in a plan view and incorporating the buffer space 21 inside, and is installed so as to be in surface contact with the upper surface of the reflector 52 which is a reflection plate of the flash lamp 69. The basic function of the reflector 52 is to reflect the flash light emitted from the plurality of flash lamps 69 toward the holding unit 7. The reflector 52 is formed of an aluminum alloy plate, and the surface (the surface facing the flash lamp 69) 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, a regular pattern is generated in the intensity of the reflected light from the plurality of flash lamps 69, and the surface temperature distribution of the semiconductor wafer W This is because the uniformity is lowered. The reflector 52 may be affixed to the outer surface of the bottom of the cooling box 20, or the reflector 52 and the cooling box 20 may be integrally formed.

  A predetermined gas (nitrogen gas in the present embodiment) is supplied from the gas supply unit 30 to the buffer space 21 of the cooling box 20. The gas supply unit 30 is configured by inserting a manual valve 31, a regulator 32, an air operation valve 33, a flow meter 34 and a filter 35 into a gas pipe 37. The gas supply unit 30 includes a pressure gauge 36. The distal end of the gas pipe 37 is connected to the buffer space 21, and the base end thereof is connected to the nitrogen gas supply source 99. As the nitrogen gas supply source 99, a utility of a factory where the heat treatment apparatus 1 is installed can be used.

  The manual valve 31 is a valve that manually opens and closes the gas pipe 37. The regulator 32 performs a pressure regulation operation of the nitrogen gas passing through the gas pipe 37. The air operating valve 33 is provided to close the gas pipe 37 in an emergency, and is opened during normal operation of the heat treatment apparatus 1. The flow meter 34 measures the flow rate of nitrogen gas passing through the gas pipe 37, and the pressure gauge 36 measures the pressure. The filter 35 removes fine particles from the nitrogen gas passing through the gas pipe 37 and purifies it. The pressure gauge 36 measures the pressure in the gas pipe 37 on the downstream side of the filter 35, and the pressure is equal to the pressure in the buffer space 21. That is, the pressure measured by the pressure gauge 36 is the pressure in the buffer space 21.

  The flow meter 34, the pressure gauge 36 and the regulator 32 are connected to the control unit 3, and the control unit is based on the measurement results of the flow meter 34 and the pressure gauge 36 with the manual valve 31 and the air operation valve 33 opened. 3 controls the regulator 32, the flow rate of nitrogen gas supplied from the nitrogen gas supply source 99 to the buffer space 21 via the gas pipe 37 can be adjusted. Further, the operator of the heat treatment apparatus 1 may adjust the flow rate of nitrogen gas supplied to the buffer space 21 by manually adjusting the set value of the regulator 32 while monitoring the flow meter 34 and the pressure gauge 36. Note that a mass flow meter having both functions may be used instead of the flow meter 34 and the regulator 32.

  A plurality of ejection holes 22 are formed through the low wall surface of the cooling box 20 and the reflector 52. Each ejection hole 22 is a cylindrical hole having a diameter of φ0.5 mm or more and φ1.5 mm or less, and is formed such that the axial direction of the cylinder is along the vertical direction. The upper ends of the respective ejection holes 22 are opened and communicated with the buffer space 21. On the other hand, the lower end of the ejection hole 22 opens toward a light source composed of a plurality of flash lamps 69.

  FIG. 6 is a plan view showing the arrangement of the ejection holes 22 in the first embodiment. In the first embodiment, the plurality of ejection holes 22 are arranged in a lattice pattern, and each of the plurality of ejection holes 22 is directly above one of the plurality of flash lamps 69 (strictly speaking, the discharge tube of the flash lamp 69 is a discharge tube). (Directly above). A row of ejection holes 22 is formed immediately above all the flash lamps 69. Accordingly, the nitrogen gas supplied to the buffer space 21 is ejected toward the flash lamp 69 from each of the plurality of ejection holes 22.

  Returning to FIG. 1, the lamp house 5 is provided with an air supply port 55 and an exhaust port 56. The exhaust port 56 is connected to an exhaust mechanism (not shown) through an exhaust pipe 57. An exhaust valve 58 is interposed in the course of the exhaust pipe 57. By opening the exhaust valve 58, a negative pressure acts on the lamp house 5 through the exhaust port 56, and as a result, outside air (air) is sucked from the air supply port 55. The air sucked from the air supply port 55 flows between the reflector 52 and the lamp light emission window 53, that is, around the plurality of flash lamps 69 in a substantially horizontal direction and is discharged from the exhaust port 56. Yes. An air supply mechanism that supplies air to the air supply port 55 may be provided.

  The hardware configuration of the control unit 3 shown in FIG. 1 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, and control applications and data. It is equipped with a magnetic disk. The control unit 3 controls the motor 40, the valves 82 and 87, the power supply circuit to the flash lamp 69, and the gas supply unit 30.

  The heat treatment apparatus 1 of the first embodiment has a cooling structure (not shown) for preventing an excessive temperature rise of the chamber 6 due to thermal energy generated from the flash lamp 69 and the hot plate 71 during the heat treatment of the semiconductor wafer W. ). Specifically, water-cooled tubes are provided on the chamber side 63 and the chamber bottom 62 of the chamber 6 so that the heat received by the chamber 6 is discharged.

  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 impurities are added by an ion implantation method, and the added impurities are activated by heat treatment by the heat treatment apparatus 1.

  First, the holding unit 7 is lowered from the processing position shown in FIG. 4 to the delivery position shown in FIG. The “processing position” is the position of the holding unit 7 when the flash light is applied to the semiconductor wafer W from the flash lamp 69, and is the 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 is placed and held on the upper surface of the susceptor 72. When the holding unit 7 moves up to the processing position, the semiconductor wafer W placed on 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 resistance heating wire individually disposed inside each zone (between the upper plate 73 and the lower plate 74). 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 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 600 ° 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 69 of the lamp house 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 69 goes directly into the chamber 6, and another 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. Since the flash heating is performed by flash irradiation from the flash lamp 69, 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 69 of the lamp house 5 is converted to a light pulse whose electrostatic energy stored in advance is extremely short, and the irradiation time is about 0.1 to 10 milliseconds. A short and strong flash. Then, the surface temperature of the semiconductor wafer W flash-heated by flash light irradiation from the flash lamp 69 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.

  Further, 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 rapidly raised to the processing temperature T2 by flash irradiation from the flash lamp 69.

  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 repeatedly performing a series of flash heating processes as described above, the discharge tube of the flash lamp 69 is gradually stored and its temperature rises. This is more influenced by radiant heat from the hot plate 71 of the holding portion 7 than by the instantaneous pulse emission of the flash lamp 69 itself. That is, the hot plate 71 is heated to about 200 ° C. to 600 ° C. to preheat the semiconductor wafer W, and emits infrared rays having a relatively long wavelength. Long wavelength infrared rays are also absorbed by quartz. For this reason, the infrared rays radiated from the hot plate 71 are first absorbed by the quartz chamber window 61 of the chamber 6 and the chamber window 61 is heated. In particular, in the heat treatment apparatus 1 of the present embodiment, since the reference position of the holding unit 7 is a processing position close to the chamber window 61, the hot plate 71 is placed in the chamber window 61 except when the semiconductor wafer W is carried in and out. The chamber window 61 is easily heated by the radiant heat from the hot plate 71.

  When the temperature of the chamber window 61 is increased, infrared light having a long wavelength is also emitted from the chamber window 61, whereby the temperature of the lamp light emission window 53 (made of quartz) of the lamp house 5 is increased. Then, long-wavelength infrared light is also emitted from the lamp light emission window 53 that has been heated, and the infrared light is absorbed by the discharge tube (made of quartz) of the flash lamp 69, and the temperature of the flash lamp 69 rises. . As described above, the discharge tube of the flash lamp 69 is indirectly heated by the radiant heat from the hot plate 71 through the chamber window 61 and the lamp light radiation window 53. Since infrared radiation is continuously emitted from the hot plate 71, heat is gradually stored in the flash lamp 69 and its temperature rises. The flash lamp 69 is also heated by radiant heat from the preheated semiconductor wafer W.

  In the heat treatment apparatus 1, an air flow is formed between the reflector 52 and the lamp light emission window 53 by the air supply port 55 and the exhaust port 56 so that the heat accumulated in the lamp house 5 is discharged. However, this is not sufficient to cool the flash lamp 69 heated by the radiant heat from the hot plate 71 and the semiconductor wafer W, and the deterioration of the flash lamp 69 is accelerated by heating, and the life may be shortened or burst. There is also.

  For this reason, in the heat treatment apparatus 1 of the present embodiment, nitrogen gas is ejected from the ejection hole 22 of the cooling box 20 toward the flash lamp 69. At this time, the gas supply unit 30 supplies nitrogen gas to the buffer space 21 so that the atmospheric pressure in the buffer space 21 becomes approximately twice or more the atmospheric pressure around the cooling box 20. Specifically, the control unit 3 may control the regulator 32 to adjust the flow rate of nitrogen gas supplied to the buffer space 21 based on the measurement result of the pressure gauge 36 that measures the atmospheric pressure in the buffer space 21. The operator may adjust the regulator 32 while monitoring the pressure gauge 36. Usually, since the atmospheric pressure around the cooling box 20 in the lamp house 5 is approximately atmospheric pressure (101325 Pa), the atmospheric pressure in the buffer space 21 is 0.19 MPa or more, that is, the atmospheric pressure in the buffer space 21 is around the cooling box 20. The gas supply unit 30 supplies nitrogen gas to the buffer space 21 so as to be approximately twice or more of the atmospheric pressure.

  When the atmospheric pressure in the buffer space 21 becomes approximately twice or more the atmospheric pressure around the cooling box 20, a nitrogen gas flow having a flow velocity higher than the transonic speed is ejected from each of the plurality of ejection holes 22. The “transonic speed” in this specification is about Mach 0.7 or more. The higher the atmospheric pressure in the buffer space 21 exceeds approximately twice the atmospheric pressure around the cooling box 20, the faster nitrogen gas is ejected from the ejection holes 22.

  In the first embodiment, since nitrogen gas is ejected from each of the plurality of ejection holes 22 toward one of the plurality of flash lamps 69, each flash lamp 69 has a nitrogen gas flow at a flow velocity of transonic speed or higher. It will be sprayed directly. Further, since the flash lamp 69 is disposed along the horizontal direction and the ejection hole 22 is formed along the vertical direction, the nitrogen gas having a flow velocity of transonic or higher is perpendicular to the discharge tube of the flash lamp 69. A stream is sprayed. Further, since the nitrogen gas supplied from the gas supply unit 30 is once stored in the buffer space 21 and then ejected from the plurality of ejection holes 22, the nitrogen gas flow is uniformly supplied from each of the plurality of ejection holes 22 to the flash lamp 69. Can be erupted.

  The airflow formed between the reflector 52 and the lamp light emission window 53 by the air supply port 55 and the exhaust port 56 has a relatively slow flow rate and tends to be a laminar flow. When a laminar flow flows around the discharge tube of the flash lamp 69, a static gas layer is formed at the interface between the tube wall and the outside air due to the viscosity of the air flow and the friction of the tube wall of the discharge tube. The heat exchange with is suppressed. On the other hand, the nitrogen gas flow having a flow velocity exceeding the transonic speed ejected from the ejection hole 22 is a turbulent flow having a high Reynolds number. For this reason, a stationary gas layer is not easily formed at the interface between the tube wall of the discharge tube and the nitrogen gas flow, and heat exchange between the nitrogen gas and the discharge tube is actively performed. As a result, each flash lamp 69 is effectively cooled, the temperature rise of each flash lamp 69 is suppressed, deterioration is prevented, and the life of the discharge tube can be extended. Of course, if the temperature rise of the flash lamp 69 can be suppressed, the lamp can be prevented from bursting. Further, if the flash lamp 69 can be effectively cooled, the preheating temperature of the semiconductor wafer W by the hot plate 71 can be set high, and the processing conditions for the annealing treatment of the semiconductor wafer W can be widened. Can do. The nitrogen gas ejected from the cooling box 20 is exhausted from the exhaust port 56 to the outside.

<2. 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 substantially the same as the apparatus configuration of the first embodiment shown in FIGS. 1 and 4, and the processing procedure of the semiconductor wafer W in the heat treatment apparatus of the second embodiment is also the first. It is the same as the embodiment. The heat treatment apparatus of the second embodiment is different from the first embodiment in the arrangement of a plurality of ejection holes 22 provided in the cooling box 20.

  FIG. 7 is a plan view showing the arrangement of the ejection holes 22 in the second embodiment. In the second embodiment, the plurality of ejection holes 22 are arranged in a staggered manner, and each of the plurality of ejection holes 22 is provided to be positioned immediately above the gap between the lamps in the arrangement of the plurality of flash lamps 69. ing. Accordingly, the nitrogen gas supplied to the buffer space 21 is ejected from each of the plurality of ejection holes 22 toward the gap between the adjacent flash lamps 69. In addition, the shape of each ejection hole 22 is the same as 1st Embodiment.

  Also in the second embodiment, the gas supply unit 30 supplies nitrogen gas to the buffer space 21 so that the atmospheric pressure in the buffer space 21 becomes approximately twice or more the atmospheric pressure around the cooling box 20. Therefore, a nitrogen gas flow having a flow velocity higher than the transonic speed is ejected from each of the plurality of ejection holes 22. In the second embodiment, since nitrogen gas is ejected from each of the plurality of ejection holes 22 toward the gap between the adjacent flash lamps 69, nitrogen gas having a flow velocity of transonic or higher is directly applied to each flash lamp 69. The flow is not blown. However, the nitrogen gas flow ejected from the ejection hole 22 at a transonic speed or higher is turbulent, and is turbulent on the side wall surfaces of both discharge tubes of the adjacent flash lamps 69 sandwiching the ejection hole 22. A stream of nitrogen gas will flow.

  Therefore, as in the first embodiment, a static gas layer is not formed at the interface between the tube wall of the discharge tube of the flash lamp 69 and the nitrogen gas flow, and heat exchange between the nitrogen gas and the discharge tube is performed. Will be performed actively. As a result, each flash lamp 69 is effectively cooled, the temperature rise of each flash lamp 69 is suppressed, deterioration is prevented, and the life of the discharge tube can be extended. Further, similarly to the first embodiment, the preheating temperature of the semiconductor wafer W by the hot plate 71 can be set high, and the processing conditions for the annealing treatment of the semiconductor wafer W can be widened. Moreover, in the second embodiment, since the two flash lamps 69 can be cooled by the single ejection hole 22, the cooling box 20 is compared to the case where the ejection holes 22 are formed immediately above each flash lamp 69. It is possible to reduce the total number of the ejection holes 22 provided in. Therefore, the atmospheric pressure in the buffer space 21 can be made approximately twice or more the atmospheric pressure around the cooling box 20 with a smaller nitrogen gas flow rate, and a nitrogen gas flow having a transonic speed or more can be easily ejected. it can.

<3. 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, in the first embodiment, the plurality of ejection holes 22 may be arranged in a staggered manner, and each of the plurality of ejection holes 22 may be formed directly above one of the plurality of flash lamps 69. In the second embodiment, the plurality of ejection holes 22 are arranged in a lattice pattern, and each of the plurality of ejection holes 22 is formed directly above the gap between the lamps in the arrangement of the plurality of flash lamps 69. Also good.

  A larger amount of nitrogen gas can be ejected when the plurality of ejection holes 22 are arranged in a lattice shape, and the contact area between the turbulent flow of nitrogen gas and the discharge tube of the flash lamp 69 is increased to enhance the cooling effect. Can do. On the other hand, if the plurality of ejection holes 22 are arranged in a staggered manner, the total number of the ejection holes 22 can be reduced, and even if the amount of nitrogen gas supplied to the cooling box 20 is smaller, the flow velocity can easily be higher than the transonic speed. A nitrogen gas stream can be formed. In addition, it is possible to obtain a larger cooling effect if the ejection hole 22 is arranged immediately above the flash lamp 69, but it is easier to arrange nitrogen gas at a flow rate higher than the transonic speed if it is arranged just above the gap between the flash lamps 69 as described above. A flow can be formed.

  In the above embodiment, a nitrogen gas flow having a transonic speed or higher is jetted to the flash lamp 69. However, the gas type blown to the flash lamp 69 is not limited to nitrogen gas, and the cooling capacity For example, air may be used. However, since a large amount of gas is consumed in order to form a gas flow at a transonic speed or higher, inexpensive air or nitrogen gas is preferable from the viewpoint of suppressing an increase in cost.

  In each of the above embodiments, the lamp house 5 is provided with 30 flash lamps 69. However, the present invention is not limited to this, and the number of flash lamps 69 can be any number. . The flash lamp 69 is not limited to a xenon flash lamp, and may be a krypton flash lamp.

  In each of the above embodiments, 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. Absent. 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 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 figure which shows the structure of a cooling box typically. It is a top view which shows an example of arrangement | positioning of an ejection hole. It is a top view which shows the other example of arrangement | positioning of an ejection hole.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat processing apparatus 3 Control part 4 Holding part raising / lowering mechanism 5 Lamp house 6 Chamber 7 Holding part 20 Cooling box 21 Buffer space 22 Ejection hole 30 Gas supply part 52 Reflector 53 Lamp light emission window 61 Chamber window 65 Heat treatment space 69 Flash lamp 71 Hot Plate 72 Susceptor W Semiconductor wafer

Claims (8)

A heat treatment apparatus for heating a substrate by irradiating the substrate with flash light,
A holding unit for holding the substrate;
A flash lamp that emits flash light from a rod-shaped discharge tube toward the substrate held by the holding unit;
A gas storage part having a built-in buffer space and having an ejection hole that communicates with the buffer space and faces the flash lamp;
Gas is supplied to the buffer space so that the air pressure in the buffer space is twice or more the air pressure around the gas storage section, and a gas having a transonic speed or more is supplied from the ejection hole toward the flash lamp. Gas supply means for spraying ;
A heat treatment apparatus comprising: The heat treatment apparatus according to claim 1, wherein
The diameter of the said ejection hole is 0.5 mm or more and 1.5 mm or less, The heat processing apparatus characterized by the above-mentioned. A heat treatment apparatus for heating a substrate by irradiating the substrate with flash light,
A holding unit for holding the substrate;
A light source having a plurality of flash lamps arranged to emit flash light toward a substrate held by the holding unit from a rod-shaped discharge tube;
A gas storage part that has a plurality of ejection holes that communicate with the buffer space and go to the light source, with a built-in buffer space;
A gas having a flow velocity higher than transonic speed from the plurality of ejection holes toward the light source by supplying gas to the buffer space so that the atmospheric pressure in the buffer space is twice or more than the atmospheric pressure around the gas reservoir. Gas supply means for spraying ;
A heat treatment apparatus comprising: The heat treatment apparatus according to claim 3, wherein
Each of the plurality of ejection holes is formed in the gas storage portion so as to eject gas toward one of the plurality of flash lamps. The heat treatment apparatus according to claim 3, wherein
Each of the plurality of ejection holes is formed in the gas reservoir so as to eject gas toward a gap between the lamps in the array of the plurality of flash lamps. In the heat treatment apparatus according to any one of claims 3 to 5,
A diameter of each of the plurality of ejection holes is not less than 0.5 mm and not more than 1.5 mm. In the heat treatment apparatus according to any one of claims 3 to 6,
The said holding | maintenance part is equipped with the preheating mechanism which preheats the board | substrate hold | maintained before flash light irradiation, The heat processing apparatus characterized by the above-mentioned. A heat treatment apparatus for heating a substrate by irradiating the substrate with flash light,
A holding unit for holding the substrate;
A flash lamp that emits flash light from a rod-shaped discharge tube toward the substrate held by the holding unit;
A gas ejection part for blowing gas at a transonic speed or higher toward the flash lamp;
A heat treatment apparatus comprising:

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