JP2010225646A - Susceptor for heat treatment and heat treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a susceptor for heat treatment, which prevents cracks of a substrate in irradiating flash light, suppresses lateral slipping of the substrate, and is manufactured relatively easily. <P>SOLUTION: The susceptor 72 mounted on a hot plate 71 includes a concave part 79 of a concave surface shape. A semiconductor wafer W is held inside the concave part 79. Six guide pins 75 are vertically arranged on the concave part 79. The six guide pins 75 are arranged so as to surround a periphery of the semiconductor wafer W. An upper surface of each guide pin 75 is a tapered surface with a gradient α 5-30°. The guide pins 75 having such the tapered surface can prevent cracks and can suppress lateral slipping even when the semiconductor wafer W is thermally expanded rapidly in irradiating flash light. In addition, bar-like guide pins 75 are vertically arranged on the concave part 79 of constant curvature, and thus the susceptor 72 can be manufactured relatively easily. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is an object to be processed when a semiconductor wafer, a glass substrate for a liquid crystal display device or the like (hereinafter simply referred to as “substrate”) is irradiated with flash light (flash light) from a flash lamp. The present invention relates to a heat treatment susceptor that holds a substrate and a heat treatment apparatus including the heat treatment susceptor.

  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 has been 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, only the surface of the semiconductor wafer into which ions have been implanted by irradiating the surface of the semiconductor wafer with flash light using a xenon flash lamp (hereinafter simply referred to as “xenon flash lamp”). There has been proposed a technique for raising the temperature of the material in an extremely short time (several milliseconds or less). The radiation spectral distribution of a xenon flash lamp ranges from the ultraviolet region to the near infrared region, has a shorter wavelength than the conventional halogen lamp, and almost coincides with the fundamental absorption band of a silicon semiconductor wafer. Therefore, when the semiconductor wafer is irradiated with flash light from the xenon flash lamp, the semiconductor wafer can be rapidly heated with little transmitted light. It has also been found that if the flash irradiation is performed for a very short time of several milliseconds or less, only the vicinity of the surface of the semiconductor wafer can be selectively heated. For this reason, if the temperature is raised by a flash lamp for a very short time, only ion activation can be performed without deeply diffusing ions.

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

  Although the use of a susceptor as disclosed in Patent Document 1 can prevent the semiconductor wafer from cracking to some extent when a flash lamp is used, the type of semiconductor wafer and heat treatment conditions (preheating temperature, irradiation) Depending on the energy, cracks still occurred with considerable frequency. For this reason, Patent Document 2 proposes a technique in which a concave surface is formed on the upper surface of the susceptor and the semiconductor wafer is held inside the concave surface.

JP 2004-179510 A JP 2007-5532 A

  The concave susceptor disclosed in Patent Document 2 is very effective in preventing cracking of a semiconductor wafer. On the other hand, the peripherally tapered surface disclosed in Patent Document 1 is effective not only for preventing the semiconductor wafer from cracking but also for preventing the semiconductor wafer from sliding. That is, it has been found that the semiconductor wafer slides because a thin gas layer is sandwiched between the semiconductor wafer and the susceptor immediately after the semiconductor wafer is placed on the susceptor or immediately after the flash lamp emits light. The tapered surface disclosed in Patent Document 1 is effective in stopping such a side slip of the semiconductor wafer.

  Therefore, if the tapered surface disclosed in Patent Document 1 is formed in the peripheral portion of the concave-shaped susceptor disclosed in Patent Document 1, it prevents side skidding while preventing cracking of the semiconductor wafer during flash light irradiation. Can be considered. However, a susceptor of a heat treatment apparatus using a flash lamp is usually made of quartz, and it is extremely difficult to process the quartz into such a shape, and the cost required for the processing is enormous.

  The present invention has been made in view of the above-mentioned problems, and can prevent cracking of the substrate at the time of flash irradiation from a flash lamp, suppress the side slip of the substrate, and can be manufactured relatively easily. An object of the present invention is to provide a susceptor for heat treatment and a heat treatment apparatus provided with the susceptor for heat treatment.

  In order to solve the above-mentioned problems, the invention of claim 1 is directed to a heat treatment susceptor that holds a substrate when the substrate is heat-treated by irradiating flash light from a flash lamp onto the substrate. A concave portion having a concave shape larger than the size, and a plurality of pins standing in the concave portion and arranged so as to surround the periphery of the substrate placed in the concave portion, and the upper surfaces of the plurality of pins are in relation to a horizontal plane The taper surface has a slope of 5 ° or more and 30 ° or less.

  According to a second aspect of the present invention, in the susceptor for heat treatment according to the first aspect of the present invention, the concave portion has a concave shape with a constant curvature.

  According to a third aspect of the present invention, in the susceptor for heat treatment according to the first or second aspect of the present invention, each of the plurality of pins has a lowest end portion having a lowest height among edge portions of the upper surface. It is erected so as to face the center of the substrate placed in the recess, and the height position of the recess at the lowest end is equal to the height position of the upper surface.

  According to a fourth aspect of the present invention, in the heat treatment susceptor according to any one of the first to third aspects of the present invention, the side surfaces of the plurality of pins are tapered surfaces.

  According to a fifth aspect of the present invention, in the heat treatment susceptor according to any one of the first to third aspects of the present invention, the heat treatment susceptor further includes a rotation preventing member that prevents rotation of the plurality of pins.

  According to a sixth aspect of the present invention, in a heat treatment apparatus for heating a substrate by irradiating the substrate with flash light, the flash lamp for irradiating the substrate with flash light, the flash lamp provided below the flash lamp, And a holding means for holding the substrate in a horizontal posture in the chamber, the holding means comprising: a chamber window that transmits a flash light emitted from the chamber; It has the susceptor for heat treatment described in any one of the above.

  According to the first to fifth aspects of the present invention, a plurality of pins are erected in a concave concave portion so as to surround the periphery of the substrate, and the upper surface of the pins has a tapered surface with a gradient of 5 ° or more and 30 ° or less with respect to the horizontal plane. Therefore, even if the substrate suddenly undergoes thermal expansion when the flash lamp is irradiated with flash light from the flash lamp, it is possible to prevent the substrate from cracking and to suppress the side slip of the substrate. In addition, since a plurality of pins are erected in the concave concave portion, the heat treatment susceptor can be manufactured relatively easily.

  In particular, according to the invention of claim 2, since the concave shape has a constant curvature, the concave portion can be easily processed.

  In particular, according to the invention of claim 3, each of the plurality of pins is erected so that the lowest end of the lowest edge among the edge portions of the upper surface faces the center of the substrate, and the lowest end thereof. Since the height position of the recess in the portion is equal to the height position of the upper surface, the recess and the upper surface of the pin are continuous at the lowest end portion, so that it is possible to reliably prevent the substrate from cracking and skidding.

  In particular, according to the invention of claim 4, since the side surfaces of the plurality of pins are tapered surfaces, it is possible to prevent the rotational displacement of the pins.

  In particular, according to the fifth aspect of the present invention, since the anti-rotation member for preventing the rotation of the plurality of pins is further provided, it is possible to prevent the pin from being displaced.

  According to the invention of claim 6, since the holding means of the heat treatment apparatus has the heat treatment susceptor according to any one of claims 1 to 5, the heat treatment is performed by flash irradiation in the heat treatment apparatus. The substrate can be prevented from cracking and the side slip of the substrate can be suppressed.

It is a longitudinal cross-sectional 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 of a susceptor. It is a perspective view of a guide pin. It is the top view and side view of a guide pin. It is a top view which shows a hot plate. It is a longitudinal cross-sectional view which shows the structure of the heat processing apparatus of FIG. It is a figure which shows the state in which a part of semiconductor wafer is contacting the guide pin. It is a side view which shows the other example of a guide pin. It is the top view and side view which show the other example of a guide pin.

  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 longitudinal sectional view showing a configuration of a heat treatment apparatus 1 according to the present invention. The heat treatment apparatus 1 is a lamp annealing apparatus that irradiates a substantially circular semiconductor wafer W as a substrate with 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 FL. 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 functions as a quartz window that transmits the 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. 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) via 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 in a horizontal position in the chamber 6 and performs preheating of the semiconductor wafer W held before light irradiation, and a holding unit. And a holding unit elevating mechanism 4 that elevates 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 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.

  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.

  FIG. 4 is a plan view of the susceptor 72. The susceptor 72 is a disk-shaped member made of quartz, and is placed on the hot plate 71 with its lower surface being in surface contact with the upper surface of the hot plate 71. On the upper surface of the susceptor 72, a concave portion 79 having a concave shape having an outer diameter larger than the diameter of the semiconductor wafer W in plan view is formed. That is, when the susceptor 72 is viewed from above, the concave shape of the concave portion 79 is larger than the planar size of the semiconductor wafer W. The concave shape defining the concave portion 79 has a certain radius of curvature.

  A plurality (six in this embodiment) of guide pins 75 are provided upright in the recess 79 of the susceptor 72. Specifically, the guide pin 75 is erected by being fitted into a mounting hole formed in the upper surface of the susceptor 72. The six guide pins 75 are arranged on a common circumference, and the diameter of the circle is larger than the diameter of the semiconductor wafer W. That is, the six guide pins 75 are arranged so as to surround the periphery of the semiconductor wafer W placed in the recess 79 of the susceptor 72.

  When the semiconductor wafer W is held by the susceptor 72 in which such a recess 79 is formed, the peripheral end portion of the semiconductor wafer W is supported by the inner wall surface of the recess 79 as shown in FIG. As a result, a gap in which a gas layer is sandwiched between the lower surface of the semiconductor wafer W and the surface of the susceptor 72 is formed. Further, when the semiconductor wafer W is held with its center exactly aligned with the center of the susceptor 72, the six guide pins 75 surround the periphery of the semiconductor wafer W in a non-contact manner.

  FIG. 5 is a perspective view of the guide pin 75. FIG. 6A is a plan view of the guide pin 75, and FIG. 6B is a side view of the guide pin 75. The guide pin 75 is a substantially cylindrical member made of quartz. The upper surface of the guide pin 75 is a tapered surface with a gradient α with respect to the horizontal plane of 5 ° or more and 30 ° or less (15 ° in the present embodiment). Further, two rotation adjustment holes 171 and 171 are formed in the upper surface of the guide pin 75. The two rotation adjustment holes 171 and 171 are for rotating the guide pins 75 attached to the susceptor 72 and adjusting their directions. Further, a notch 172 is formed on the side surface of the guide pin 75. The notch portion 172 is formed immediately below the highest end portion 174 having the highest height among the edge portions on the upper surface of the guide pin 75. The notch 172 is for the operator to recognize the orientation of the guide pin 75. That is, by forming the notch portion 172 in the quartz guide pin 75, the notch portion 172 looks white when viewed from above, and the operator can visually confirm the orientation of the guide pin 75. Recognize

  Each of the plurality of guide pins 75 is erected so that the lowest end portion 173 having the lowest height among the edge portions on the upper surface of the guide pins 75 faces the central portion of the semiconductor wafer W placed in the recess 79. Has been. Specifically, when the guide pin 75 is attached to the susceptor 72, the operator turns the two rotation adjustment holes 171 and 171 using tweezers or the like so that the lowest end 173 faces the center of the semiconductor wafer W. The guide pin 75 is rotated. At this time, the operator can accurately recognize the orientation of the lowest end portion 173 by visually confirming the cutout portion 172 that appears white in the transparent guide pin 75.

  As shown in FIGS. 3 and 9, the height position of the recess 79 at the lowest end 173 of the guide pin 75 attached to the susceptor 72 is equal to the height position of the upper surface of the guide pin 75. That is, in a state where the guide pin 75 is attached to the susceptor 72, the concave surface of the concave portion 79 and the tapered surface of the upper surface of the guide pin 75 are continuous at the position of the lowest end portion 173.

  Returning to FIG. 3, 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. 7 is a plan view showing the hot plate 71. As shown in FIG. 7, 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 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.

  The lamp house 5 includes a light source including a plurality of (30 in the present embodiment) xenon flash lamps FL and a reflector 52 provided so as to cover the light source inside the housing 51. Composed. 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 FL via the lamp light emission window 53 and the chamber window 61. .

  Each of the plurality of flash lamps FL is a rod-shaped lamp having a long cylindrical shape, and the longitudinal direction of each of the flash lamps FL is along the main surface of the semiconductor wafer W held by the holding unit 7 (that is, along the horizontal direction). They are arranged in a plane so as to be parallel to each other. Therefore, the plane formed by the arrangement of the flash lamps FL is also a horizontal plane.

  The xenon flash lamp FL has a rod-shaped glass tube (discharge tube) in which xenon gas is sealed and an anode and a cathode connected to a capacitor at both ends thereof, and an outer peripheral surface of the glass tube. And a triggered electrode. Since xenon gas is an electrical insulator, electricity does not flow into the glass tube under normal conditions even if electric charges are accumulated in the capacitor. However, when the insulation is broken by applying a high voltage to the trigger electrode, the electricity stored in the capacitor instantaneously flows into the glass tube due to the discharge between the electrodes at both ends, and the excitation of the xenon atoms or molecules at that time Light is emitted. In such a xenon flash lamp FL, the electrostatic energy stored in the capacitor in advance is converted into an extremely short light pulse of 0.1 millisecond to 10 millisecond, which is extremely incomparable with a continuous light source. It has the feature that it can irradiate strong light.

  In addition, the reflector 52 is provided above the plurality of flash lamps FL so as to cover all of them. The basic function of the reflector 52 is to reflect flash light emitted from the plurality of flash lamps FL toward the holding unit 7. The reflector 52 is formed of an aluminum alloy plate, and the surface (the surface facing the flash lamp FL) is roughened by blasting to exhibit a satin pattern. 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.

  Further, the control unit 3 controls the various operation mechanisms provided in the heat treatment apparatus 1. The configuration of the control unit 3 as hardware is the same as that of a general computer. That is, the control unit 3 stores a CPU that performs various arithmetic processes, a ROM that is a read-only memory that stores basic programs, a RAM that is a readable and writable memory that stores various information, control software, data, and the like. It has a magnetic disk.

  In addition to the above configuration, the heat treatment apparatus 1 is used for various cooling purposes in order to prevent excessive temperature rise of the chamber 6 and the lamp house 5 due to the heat energy generated from the flash lamp FL and the hot plate 71 during the heat treatment of the semiconductor wafer W. It has the structure of For example, water-cooled tubes (not shown) are provided on the chamber side 63 and the chamber bottom 62 of the chamber 6. The lamp house 5 has an air cooling structure provided with a gas supply pipe 55 and an exhaust pipe 56 for exhausting heat by forming a gas flow therein (see FIG. 1). Air is also supplied to the gap between the chamber window 61 and the lamp light emission window 53 to cool the lamp house 5 and the chamber window 61.

  Next, a processing procedure for the semiconductor wafer W in the heat treatment apparatus 1 will be described. Here, the semiconductor wafer W to be processed is a semiconductor substrate to which impurities (ions) are added by an ion implantation method, and activation of the added impurities is executed by light irradiation heating processing (annealing) by the heat treatment apparatus 1. . The processing procedure of the heat treatment apparatus 1 described below proceeds by the control unit 3 controlling each operation mechanism of the heat treatment apparatus 1.

  First, the holding unit 7 is lowered from the processing position shown in FIG. 8 to the delivery position shown in FIG. The “processing position” is the position of the holding unit 7 when the semiconductor wafer W is irradiated with light from the flash lamp FL, 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 is loaded into the chamber 6 through the transfer opening 66 by the transfer robot outside the apparatus and placed on the plurality of support pins 70. Is done.

  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 held in the recess 79 of the susceptor 72. At this time, the peripheral end portion of the semiconductor wafer W is supported by the inner wall surface of the recess 79 of the susceptor 72. If the center of the semiconductor wafer W exactly coincides with the center of the susceptor 72 when the holding unit 7 is raised, the semiconductor wafer W is accurately placed in the center of the recess 79 and the six guide pins 75 are formed. The periphery of the semiconductor wafer W is surrounded in a non-contact manner. However, the position of the semiconductor wafer W may be slightly shifted so that a part of the peripheral edge is in contact with the guide pins 75. When the holding unit 7 moves up to the processing position, the semiconductor wafer W supported 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.

  After the preheating time of about 60 seconds elapses, flash light is irradiated from the flash lamp FL 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 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 flash heating is performed by flash light irradiation from the flash lamp FL, the surface temperature of the semiconductor wafer W can be increased in a short time.

  In other words, the flash light emitted from the flash lamp FL 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. The surface temperature of the semiconductor wafer W flash-heated by flash light 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 converted, the surface temperature rapidly decreases. As described above, in the heat treatment apparatus 1, the surface temperature of the semiconductor wafer W can be raised and lowered in a very short time, so that the impurities are activated while suppressing diffusion of impurities added to the semiconductor wafer W due to heat. Can do. Since the time required for activation of the added impurity is extremely short compared to the time required for thermal diffusion, activation is possible even for a short time when no diffusion of about 0.1 millisecond to 10 millisecond occurs. Is completed.

  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 quickly raised to the processing temperature T2 by the flash light 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, the surface temperature of the semiconductor wafer W that is flash-heated by flash irradiation of several milliseconds from the flash lamp FL instantaneously rises to a processing temperature T2 of about 1000 ° C. to 1100 ° C., while the back surface temperature at that moment is The temperature does not increase so much from the preheating temperature T1 of about 350 ° C. to 550 ° C. For this reason, rapid thermal expansion occurs only on the wafer surface side, and the semiconductor wafer W warps so that the upper surface is convex. Then, at the next moment, the surface temperature of the semiconductor wafer W rapidly decreases, while the back surface temperature also slightly increases due to heat conduction from the front surface to the back surface, so that the semiconductor wafer W is warped in the opposite direction. Stress to act. As a result, the semiconductor wafer W vibrates violently on the susceptor 72, and the semiconductor wafer W may be cracked by an impact at that time.

  In the present embodiment, since the semiconductor wafer W is placed in the concave recess 79, a gap in the gas layer is formed between the surface of the susceptor 72 and the lower surface of the semiconductor wafer W. Even if the semiconductor wafer W vibrates violently during light irradiation, the lower surface of the semiconductor wafer W does not collide with the surface of the susceptor 72, and cracking of the semiconductor wafer W can be prevented. At this time, as shown in FIG. 9, even if a part of the peripheral edge of the semiconductor wafer W is in contact with the guide pin 75, the upper surface of the quartz guide pin 75 is a tapered surface with a gradient α = 15 °. Therefore, even if the semiconductor wafer W is thermally expanded rapidly, the peripheral edge can slide up the upper surface of the guide pin 75. Therefore, the peripheral portion of the semiconductor wafer W is not constrained by the guide pins 75, and even if the semiconductor wafer W undergoes rapid thermal expansion during flash light irradiation, it does not receive a large stress from the guide pins 75, and the semiconductor wafer W Can be prevented. In order for the peripheral portion of the semiconductor wafer W to slide up the upper surface of the guide pin 75 during rapid thermal expansion, the upper surface of the guide pin 75 needs to be a tapered surface with a gradient α of 30 ° or less with respect to the horizontal plane.

  Further, when the holding unit 7 is raised and the semiconductor wafer W is transferred to the susceptor 72, or when the semiconductor wafer W is irradiated with flash light, there is a possibility that the semiconductor wafer W slides, but the upper surface of the guide pins 75 surrounding the semiconductor wafer W is Since the taper surface has a gradient α = 15 °, the side slip of the semiconductor wafer W can be suppressed. In order to obtain such a side slip suppression effect, the upper surface of the guide pin 75 needs to be a tapered surface having a gradient α of 5 ° or more with respect to the horizontal plane.

  Further, since the concave portion 79 of the susceptor 72 has a concave shape with a constant curvature, the concave portion 79 can be formed by processing a quartz plate relatively easily. Further, the guide pin 75 can be easily manufactured by simple processing. The susceptor 72 can be manufactured simply by standing the guide pin 75 in the recess 79. Therefore, the susceptor 72 can be manufactured very easily compared to the process of forming the tapered surface on the peripheral edge of the concave surface, and the cost required for the susceptor 72 can be suppressed.

  Even if the guide pin 75 is slightly rotated, the upper surface of the guide pin 75 is a taper surface, so that the semiconductor wafer W comes close to the guide pin 75 and its peripheral portion contacts the taper surface of the guide pin 75. Then, a moment that corrects the rotational deviation is generated. That is, a slight rotational deviation of the guide pin 75 is automatically corrected.

  While the embodiments of the present invention have been described above, the present invention can be modified in various ways other than those described above without departing from the spirit of the present invention. For example, in the above-described embodiment, the side surface of the guide pin 75 is cylindrical, but this may be a tapered surface. As shown in FIG. 10, if a tapered surface is formed on the side surface of the guide pin 175, the guide pin 175 is mounted in a wedge shape with respect to the mounting hole of the susceptor 72, and the rotation displacement of the guide pin 175 can be prevented. The upper surface of the guide pin 75 is also a tapered surface having a gradient α with respect to the horizontal plane of 5 ° or more and 30 ° or less.

  Further, as shown in FIG. 11, a rotation preventing claw 179 may be attached to the guide pin 75. FIG. 11A is a plan view of the guide pin 75 provided with the rotation preventing claw 179, and FIG. 11B is a longitudinal sectional view thereof. An anti-rotation claw 179 attached to the guide pin 75 is engaged with the outer peripheral edge of the susceptor 72. For this reason, the rotation shift of the guide pin 75 is prevented. The configuration of the guide pin 75 is the same as that in the above embodiment.

  In the above embodiment, the semiconductor wafer W is preheated by the hot plate 71 on which the susceptor 72 is mounted. Instead, the semiconductor wafer is irradiated by light irradiation from a continuous lighting light source such as a halogen lamp. W preheating may be performed. Specifically, a halogen lamp is disposed below the susceptor 72, and the semiconductor wafer W is preheated by infrared rays emitted from the halogen lamp and transmitted through the quartz susceptor 72. Even when such a preheating method is adopted, by holding the semiconductor wafer W by the susceptor 72 in which a plurality of guide pins 75 are erected in the concave portion 79, the same effect as in the above embodiment can be obtained. Obtainable.

  Moreover, in the said embodiment, although the guide pin 75 was six, the number of the guide pins 75 can be made into arbitrary numbers of two or more. However, the effect of the above-described embodiment can be obtained more reliably by using three or more surrounding semiconductor wafers W.

  In the above embodiment, the lamp house 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.

  The substrate to be processed by the heat treatment apparatus according to the present invention is not limited to a semiconductor wafer, and may be a glass substrate used for a liquid crystal display device or the like.

DESCRIPTION OF SYMBOLS 1 Heat processing apparatus 3 Control part 4 Holding part raising / lowering mechanism 5 Lamphouse 6 Chamber 7 Holding part 60 Upper opening 61 Chamber window 65 Heat treatment space 71 Hot plate 72 Susceptor 75,275 Guide pin 76 Resistance heating wire 79 Recess 171 Rotation adjustment hole 172 Cutting Notch 173 Minimum end 174 Maximum end 179 Anti-rotation claw FL Flash lamp W Semiconductor wafer

Claims (6)

A susceptor for heat treatment that holds the substrate when the substrate is heat-treated by irradiating flash light onto the substrate from a flash lamp,
A concave portion having a concave shape larger than the planar size of the substrate in plan view;
A plurality of pins that are erected in the recess and arranged to surround the periphery of the substrate placed in the recess;
With
The heat treatment susceptor, wherein the upper surfaces of the plurality of pins are tapered surfaces having a gradient with respect to a horizontal plane of 5 ° to 30 °. The susceptor for heat treatment according to claim 1,
The heat treatment susceptor, wherein the recess has a concave shape with a constant curvature. In the susceptor for heat treatment according to claim 1 or 2,
Each of the plurality of pins is erected so that the lowest end of the lowest edge of the upper surface is opposed to the center of the substrate placed in the recess,
The heat treatment susceptor, wherein a height position of the recess at the lowest end is equal to a height position of the upper surface. In the susceptor for heat treatment according to any one of claims 1 to 3,
A heat-treating susceptor, wherein side surfaces of the plurality of pins are tapered surfaces. In the susceptor for heat treatment according to any one of claims 1 to 3,
A heat treatment susceptor further comprising a rotation preventing member that prevents rotation of the plurality of pins. A heat treatment apparatus for heating a substrate by irradiating a flash with the substrate,
A flash lamp that irradiates the substrate with flash light;
A chamber provided below the flash lamp, and provided with a chamber window at the top for transmitting flash light emitted from the flash lamp;
Holding means for holding the substrate in a horizontal position in the chamber;
With
6. A heat treatment apparatus, wherein the holding means includes the heat treatment susceptor according to any one of claims 1 to 5.

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