JP2013162075A - Heat treatment apparatus and heat treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat treatment apparatus and a heat treatment method capable of equalizing in-plane temperature distribution during flashlight irradiation.SOLUTION: Due to the fact that the behavior of multiple reflection differs depending on a reflection rate of the surface of a semiconductor wafer W, an in-plane distribution of intensity of flashlight irradiated from a flash lamp FL varies, and non-uniformity of a temperature distribution occurs. The size of a shadow region formed at a peripheral edge of the semiconductor wafer W by an inner peripheral tip portion of a clamp ring 90 of a chamber 6 during flashlight irradiation is changed by moving up and down a holding part 7 for holding the semiconductor wafer W so as to eliminate the non-uniformity. Thereby, the in-plane temperature distribution of the semiconductor wafer W can be adjusted and equalized by increasing and decreasing the intensity of the flashlight that reaches the peripheral part of the semiconductor wafer W during the flashlight irradiation.

Description

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

  In the semiconductor device manufacturing process, impurity introduction is an indispensable step for forming a pn junction in a semiconductor wafer. Currently, impurities are generally introduced by ion implantation and subsequent annealing. The ion implantation method is a technique in which impurity elements such as boron (B), arsenic (As), and phosphorus (P) are ionized and collided with a semiconductor wafer at a high acceleration voltage to physically perform impurity implantation. The implanted impurities are activated by annealing. At this time, if the annealing time is about several seconds or more, the implanted impurities are deeply diffused by heat, and as a result, the junction depth becomes deeper than required, and there is a possibility that good device formation may be hindered.

  Therefore, in recent years, flash lamp annealing (FLA) has attracted attention as an annealing technique for heating a semiconductor wafer in an extremely short time. Flash lamp annealing is a semiconductor wafer in which impurities are implanted by irradiating the surface of the semiconductor wafer with flash light using a xenon flash lamp (hereinafter, simply referred to as “flash lamp” means xenon flash lamp). Is a heat treatment technique for raising the temperature of only the surface of the material in a very short time (several milliseconds or less).

  The radiation spectral distribution of a xenon flash lamp ranges from the ultraviolet region to the near infrared region, has a shorter wavelength than the conventional halogen lamp, and almost coincides with the fundamental absorption band of a silicon semiconductor wafer. Therefore, when the semiconductor wafer is irradiated with flash light from the xenon flash lamp, the semiconductor wafer can be rapidly heated with little transmitted light. Further, it has been found that if the flash light irradiation is performed for a very short time of several milliseconds or less, only the vicinity of the surface of the semiconductor wafer can be selectively heated. For this reason, if the temperature is raised for a very short time by the xenon flash lamp, only the impurity activation can be performed without deeply diffusing the impurities.

  An example of a heat treatment apparatus using such a xenon flash lamp is disclosed in Patent Document 1. In the flash lamp annealing apparatus described in Patent Document 1, a semiconductor wafer preheated to a predetermined temperature by a hot plate is irradiated with flash light from a flash lamp to raise the temperature to a target processing temperature.

JP 2004-55821 A

  In a heat treatment apparatus using a flash lamp, the flash light irradiation time is extremely short, so it is not possible to finely adjust the lamp intensity during the heat treatment or to improve the in-plane temperature distribution of the wafer to be processed by rotating the semiconductor wafer. Is possible. For this reason, after adjusting the lamp intensity etc. so that the in-plane temperature distribution is uniform using a semiconductor wafer (blanket wafer) on which no pattern or film is formed on the surface, The semiconductor wafer thus made was subjected to flash heat treatment. The in-plane temperature distribution measurement using the blanket wafer may be performed by measuring the sheet resistance value after performing flash heat treatment on the blanket wafer after ion implantation. In the region where the temperature is high during flash heating, the sheet resistance value is low, and if the in-plane temperature distribution is uniform, the variation in the sheet resistance value is small.

  However, the surface reflectance of the semiconductor wafer that is actually processed is different from the reflectance of the blanket wafer. Also, the reflectance varies depending on the type of pattern or film formed between semiconductor wafers to be processed. For this reason, even if the blanket wafer is adjusted so that the in-plane temperature distribution is uniform, when the semiconductor wafer to be actually processed is irradiated with flash light, the temperature of the peripheral portion becomes higher than that of the central portion. As a result, the temperature distribution becomes uneven.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a heat treatment apparatus and a heat treatment method that can make the in-plane temperature distribution during flash light irradiation uniform.

  In order to solve the above-mentioned problems, a first aspect of the present invention provides a heat treatment apparatus for heating a substrate by irradiating the substrate with flash light, a chamber for accommodating the substrate, and a holding means for holding the substrate in the chamber. A flash lamp that irradiates flash light onto one surface of the substrate held by the holding means, and an intensity adjusting means that adjusts the intensity of the flash light reaching the peripheral edge of the substrate according to the reflectance of the one surface And.

  The invention of claim 2 is the heat treatment apparatus according to claim 1 of the invention, wherein the intensity adjusting means increases the intensity of flash light reaching the peripheral portion when the reflectance of the one surface increases. If the reflectance of the one surface is lowered, the intensity of flash light reaching the peripheral portion is reduced.

  The invention of claim 3 is the heat treatment apparatus according to claim 2, wherein the flash lamp is disposed above the chamber and in a region wider than the optical window of the chamber, and the intensity adjusting means includes: Elevating means for elevating and lowering the holding means in the chamber, and the elevating means raises the holding means when the reflectance of the one surface increases, and the peripheral portion of the substrate by the chamber during flash light irradiation The shadow area formed on the surface is reduced, and when the reflectance of the one surface becomes low, the holding means is lowered to enlarge the shadow area.

  According to a fourth aspect of the present invention, in the heat treatment apparatus according to the third aspect of the present invention, the intensity adjusting unit holds a correlation table in which the reflectance of the one surface is associated with the height position of the holding unit. The holding means is moved up and down based on the correlation table.

  The invention according to claim 5 is the heat treatment apparatus according to any one of claims 1 to 4, further comprising a reflectance measuring means for measuring the reflectance of the one surface.

  According to a sixth aspect of the present invention, in the heat treatment method for heating a substrate by irradiating the substrate with flash light, one surface of the substrate held by the holding means in the chamber is irradiated with flash light from a flash lamp. A flash light irradiating step; and an intensity adjusting step of adjusting the intensity of the flash light reaching the peripheral edge of the substrate in accordance with the reflectance of the one surface.

  Further, the invention of claim 7 is the heat treatment method according to the invention of claim 6, wherein, in the intensity adjustment step, if the reflectance of the one surface is increased, the intensity of the flash light reaching the peripheral portion is increased, If the reflectance of the one surface is lowered, the intensity of flash light reaching the peripheral portion is reduced.

  The invention of claim 8 is the heat treatment method according to the invention of claim 7, wherein the flash lamp is disposed above the chamber and in a region wider than the optical window of the chamber, and in the intensity adjustment step, If the reflectance of the one surface increases, the holding means is raised to reduce the shadow area formed on the peripheral edge of the substrate by the chamber during flash light irradiation, and the reflectance of the one surface decreases. The shadowing area is enlarged by lowering the holding means.

  Further, the invention of claim 9 is the heat treatment method according to the invention of claim 8, in the intensity adjustment step, based on a correlation table in which the reflectance of the one surface and the height position of the holding means are associated with each other. The holding means is raised and lowered.

  The invention of claim 10 is the heat treatment method according to any one of claims 6 to 9, further comprising a reflectance measurement step of measuring the reflectance of the one surface.

  According to the first to fifth aspects of the present invention, since the intensity of the flash light reaching the peripheral edge of the substrate is adjusted according to the reflectance of the one surface of the substrate held by the holding means, the difference in reflectance is caused. The inhomogeneous temperature distribution caused can be eliminated and the in-plane temperature distribution of the substrate at the time of flash light irradiation can be made uniform.

  According to the inventions of claims 6 to 10, in order to adjust the intensity of the flash light reaching the peripheral portion of the substrate according to the reflectance of the one surface of the substrate held by the holding means, The uneven temperature distribution due to the difference can be eliminated, and the in-plane temperature distribution of the substrate at the time of flash light irradiation can be made uniform.

It is a top view which shows the heat processing apparatus which concerns on this invention. It is a front view of the heat processing apparatus of FIG. It is a longitudinal cross-sectional view which shows the structure of a flash heating part. It is sectional drawing which shows the gas path of a flash heating part. It is sectional drawing which shows the structure of a holding | maintenance part. It is a top view which shows a hot plate. It is a longitudinal cross-sectional view which shows the structure of the flash heating part of FIG. It is a figure which shows the structure of an alignment part. It is a figure which shows the hardware constitutions of a control part. It is a flowchart which shows the process sequence in the heat processing apparatus of FIG. It is a figure which shows typically the behavior of the multiple reflection at the time of flash light irradiation. It is a figure which shows typically the behavior of the multiple reflection at the time of flash light irradiation. It is a figure for demonstrating the correlation with the height position of the holding | maintenance part holding a semiconductor wafer, and flash light intensity. It is a figure for demonstrating the correlation with the height position of the holding | maintenance part holding a semiconductor wafer, and flash light intensity. It is a figure which shows the change of the in-plane temperature distribution of the semiconductor wafer by raising / lowering of a holding | maintenance part. It is a figure which shows an example of a correlation table.

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

<1. Configuration of heat treatment equipment>
<1-1. Overall configuration>
FIG. 1 is a plan view showing a heat treatment apparatus 100 according to the present invention, and FIG. 2 is a front view thereof. The heat treatment apparatus 100 is a flash lamp annealing apparatus that irradiates a substantially disc-shaped semiconductor wafer W as a substrate with flash light and heats the semiconductor wafer W. 1 and FIG. 2 are partially sectional views as appropriate, and details are simplified as appropriate. In addition, in FIGS. 1 and 2 and subsequent figures, an XYZ orthogonal coordinate system in which the Z-axis direction is the vertical direction and the XY plane is the horizontal plane is attached as necessary to clarify the directional relationship. .

  As shown in FIGS. 1 and 2, the heat treatment apparatus 100 includes an indexer unit 101 for loading an unprocessed semiconductor wafer W into the apparatus and unloading the processed semiconductor wafer W outside the apparatus, and an unprocessed semiconductor. Alignment unit 130 for positioning wafer W, cooling unit 140 for cooling semiconductor wafer W after the heat treatment, flash heating unit 160 for performing flash heat treatment on semiconductor wafer W, alignment unit 130, cooling unit 140, and flash heating unit A transport robot 150 that transports a semiconductor wafer W to 160 is provided. Further, the heat treatment apparatus 100 includes a control unit 3 that controls the operation mechanism and the transfer robot 150 provided in each processing unit described above to advance the flash heating process of the semiconductor wafer W.

  The indexer unit 101 loads a plurality of carriers C (two in this embodiment) side by side and loads the unprocessed semiconductor wafers W from the carriers C, and processes the semiconductor wafers processed by the carriers C. And a delivery robot 120 for storing W. The carrier C containing the unprocessed semiconductor wafer W is transported by an automatic guided vehicle (AGV) or the like and placed on the load port 110, and the carrier C containing the processed semiconductor wafer W is loaded by the automatic guided vehicle. Taken away from port 110. Further, the load port 110 is configured such that the carrier C can be moved up and down as indicated by an arrow CU in FIG. 2 so that the delivery robot 120 can take in and out an arbitrary semiconductor wafer W with respect to the carrier C. ing. As a form of the carrier C, in addition to a FOUP (front opening unified pod) for storing the semiconductor wafer W in a sealed space, a standard mechanical interface (SMIF) pod and an OC (open for exposing the stored semiconductor wafer W to the open air) cassette).

  In addition, the delivery robot 120 is capable of sliding movement as indicated by an arrow 120S, turning operation and raising / lowering operation as indicated by an arrow 120R. As a result, the delivery robot 120 carries the semiconductor wafer W in and out of the two carriers C, and delivers the semiconductor wafer W to the alignment unit 130 and the cooling unit 140. The delivery / removal robot 120 moves the semiconductor wafer W in and out of the carrier C by sliding the hand 121 and moving the carrier C up and down. Further, the delivery of the semiconductor wafer W between the delivery robot 120 and the alignment unit 130 or the cooling unit 140 is performed by the sliding movement of the hand 121 and the lifting operation of the delivery robot 120.

  The alignment unit 130 is a processing unit that rotates the semiconductor wafer W and directs the semiconductor wafer W in an appropriate direction for subsequent flash heating. The semiconductor wafer W is delivered from the delivery robot 120 to the alignment unit 130 so that the wafer center is located at a predetermined position. The alignment unit 130 positions the semiconductor wafer W by optically detecting notches, orientation flats, and the like by rotating about the central axis of the semiconductor wafer W received from the indexer unit 101 around the vertical axis. Moreover, the alignment part 130 is provided with the below-mentioned optical measurement unit, and measures the reflectance of the semiconductor wafer W used as the process target by the optical measurement unit.

  The flash heating unit 160, which is a main part of the heat treatment apparatus 100, is a processing unit that performs flash heating processing by irradiating flash light (flash light) from the xenon flash lamp FL onto the pre-heated semiconductor wafer W. The configurations of the flash heating unit 160 and the alignment unit 130 will be further described later.

  The cooling unit 140 is configured by placing a quartz plate on the upper surface of a metal cooling plate. Since the temperature of the semiconductor wafer W immediately after the flash heating process is performed by the flash heating unit 160 is high, the semiconductor wafer W is placed on the quartz plate and cooled by the cooling unit 140.

  The transfer robot 150 can be turned around an axis along the vertical direction as indicated by an arrow 150R, and has two link mechanisms including a plurality of arm segments. Are provided with transfer arms 151a and 151b for holding the semiconductor wafer W, respectively. These transfer arms 151a and 151b are arranged vertically apart from each other by a predetermined pitch, and can be slid linearly in the same horizontal direction independently by a link mechanism. Also, the transfer robot 150 moves up and down the two transfer arms 151a and 151b while moving away from each other by a predetermined pitch by moving up and down a base provided with two link mechanisms.

  In addition, a transfer chamber 170 that accommodates the transfer robot 150 is provided as a transfer space of the semiconductor wafer W by the transfer robot 150, and the alignment unit 130, the cooling unit 140, and the flash heating unit 160 are connected to the transfer chamber 170. ing. When the transfer robot 150 transfers (inserts / removes) the semiconductor wafer W as a transfer partner to the alignment unit 130, the flash heating unit 160, or the cooling unit 140, first, the transfer arms 151a and 151b are opposed to the transfer partner. It turns and then moves up and down (or while it is turning) so that one of the transfer arms is positioned at a height at which the semiconductor wafer W is delivered to the delivery partner. Then, the transfer arm 151a (151b) is slid linearly in the horizontal direction, and the transfer partner and the semiconductor wafer W are transferred.

  Gate valves 181 and 182 are provided between the indexer unit 101 and the alignment unit 130 and the cooling unit 140, respectively. Between the transfer chamber 170 and the alignment unit 130, the cooling unit 140 and the flash heating unit 160, respectively. Gate valves 183, 184 and 185 are provided. Then, a high-purity nitrogen gas is supplied from a nitrogen gas supply unit (not shown) so that the inside of the alignment unit 130, the cooling unit 140, and the transfer chamber 170 is kept clean, and excess nitrogen gas is appropriately exhausted. Exhausted from the tube. Note that these gate valves are appropriately opened and closed when the semiconductor wafer W is transported.

  The alignment unit 130 and the cooling unit 140 are positioned on the forward and return paths of the wafer transfer path between the indexer unit 101 and the transfer robot 150. The alignment unit 130 positions the semiconductor wafer W in order to position the semiconductor wafer W. Is temporarily placed, and the cooling unit 140 temporarily places the semiconductor wafer W in order to cool the semiconductor wafer W after the heat treatment.

<1-2. Configuration of flash heating unit>
Next, the configuration of the flash heating unit 160 will be described in detail. FIG. 3 is a longitudinal sectional view showing the configuration of the flash heating unit 160. The flash heating unit 160 includes a substantially cylindrical chamber 6 that houses the semiconductor wafer W, and a lamp house 5 that houses a plurality of flash lamps FL.

  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 flash light emitted from the flash lamp FL 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 inner peripheral tip of the clamp ring 90 protrudes inward from the chamber side 63. Therefore, the optical window 67 for guiding the flash light emitted from the flash lamp FL to the heat treatment space 65 is defined by the opening of the clamp ring 90.

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

The chamber side 63 has a transfer opening 66 for carrying in and out the semiconductor wafer W, and the transfer opening 66 can be opened and closed by a gate valve 185 that rotates about a shaft 662. In a portion of the chamber side 63 opposite to the transfer opening 66, an inert gas such as a processing gas (for example, nitrogen (N ₂ ) gas, helium (He) gas, argon (Ar) gas), etc. Alternatively, an introduction path 81 for introducing oxygen (O 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. 4 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. 4, the gas introduction buffer 83 is formed over about ３ of the inner circumference of the chamber side portion 63 on the opposite side of the transfer opening 66 shown in FIG. 3. 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.

  Returning to FIG. 3, the flash heating unit 160 holds the semiconductor wafer W in the horizontal position inside the chamber 6 and performs preheating of the semiconductor wafer W held before the flash light irradiation, while holding the semiconductor wafer W in a substantially posture. 7 and a holding unit raising / lowering mechanism 4 that raises and lowers the holding unit 7 with respect to the chamber bottom 62 which is the bottom surface of the chamber 6. 3 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. 3 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. 5 is a cross-sectional view showing the configuration of the holding unit 7. The holding unit 7 is installed on a hot plate (heating plate) 71 that preheats the semiconductor wafer W (so-called assist heating), and an upper surface of the hot plate 71 (a surface on the side where the holding unit 7 holds the semiconductor wafer W). The susceptor 72 is provided. As described above, the shaft 41 that moves up and down the holding unit 7 is connected to the lower surface of the holding unit 7. The susceptor 72 is made of quartz (or may be aluminum nitride (AIN) or the like), and a pin 75 for preventing displacement of the semiconductor wafer W is provided on the upper surface thereof. The susceptor 72 is installed on the hot plate 71 with its lower surface in surface contact with the upper surface of the hot plate 71. Thus, the susceptor 72 diffuses the thermal energy from the hot plate 71 and transmits it to the semiconductor wafer W placed on the upper surface of the susceptor 72, and can be removed from the hot plate 71 and cleaned during maintenance.

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

  FIG. 6 is a plan view showing the hot plate 71. As shown in FIG. 6, the hot plate 71 includes a disc-shaped zone 711 and an annular zone 712 that are concentrically arranged in the center of a region facing the 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 disposed in each of the six zones 711 to 716 are connected to a plate power source 98 (see FIG. 9) via a power line passing through the inside of the shaft 41. In the middle of the path from the plate power source 98 to each zone, the power lines from the plate power source 98 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 is provided above the chamber 6. 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 plane area of the plane formed by the arrangement of the plurality of flash lamps FL is larger than the optical window 67 of the chamber 6 defined by the opening of the clamp ring 90. That is, the plurality of flash lamps FL are arranged above the chamber 6 over a wider area than the optical window 67 of the chamber 6.

  The xenon flash lamp FL has a rod-shaped glass tube (discharge tube) in which xenon gas is sealed and an anode and a cathode connected to a capacitor at both ends thereof, and an outer peripheral surface of the glass tube. And a triggered electrode. Since xenon gas is an electrical insulator, electricity does not flow into the glass tube under normal conditions even if electric charges are accumulated in the capacitor. However, when the insulation is broken by applying a high voltage to the trigger electrode, the electricity stored in the capacitor flows instantaneously in the glass tube, and light is emitted by excitation of atoms or molecules of xenon at that time. In such a xenon flash lamp FL, the electrostatic energy stored in the capacitor in advance is converted into an extremely short light pulse of 0.1 millisecond to 100 millisecond. It has the feature that it can irradiate strong light. The light emission time of the flash lamp FL can be adjusted by the coil constant of a lamp power source 99 (see FIG. 9) that supplies power to the flash lamp FL.

  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.

  In addition to the above-described configuration, the flash heating unit 160 performs various cooling operations in order to prevent an excessive increase in temperature of the chamber 6 and the lamp house 5 due to thermal energy generated from the flash lamp FL and the hot plate 71 during the heat treatment of the semiconductor wafer W. It has a structure for. 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 FIGS. 3 and 7). 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.

<1-3. Configuration of alignment unit>
Next, the configuration of the alignment unit 130 will be described. FIG. 8 is a diagram illustrating a configuration of the alignment unit 130. The alignment unit 130 includes a chamber 131 and a wafer holding unit 132 and an optical measurement unit 230.

  The chamber 131 is a metal housing that houses the semiconductor wafer W. Openings (not shown) for accessing the delivery robot 120 and the transfer robot 150 are provided on the side walls of the chamber 131, and the openings are opened and closed by gate valves 181 and 183.

  A wafer holding part 132 is provided at the bottom of the chamber 131. The wafer holding unit 132 includes a rotary table 133 and an alignment motor 135. The turntable 133 supports the semiconductor wafer W from the lower surface and places it in a horizontal posture (a posture in which the normal line of the semiconductor wafer W is along the vertical direction). The rotary table 133 can be rotated around the vertical axis by an alignment motor 135.

  The optical measurement unit 230 includes a measurement optical system 231, a projector 233 coupled to the measurement optical system 231 via a light projecting optical fiber 232, and a light receiving optical fiber 234 to the measurement optical system 231. And a spectroscope 235 coupled to each other. Among the constituent elements of the optical measurement unit 230, the measurement optical system 231 is fixedly installed on the ceiling portion of the chamber 131, and the other elements are provided outside the chamber 131.

  The projector 233 contains a halogen lamp and generates a certain amount of light. The light emitted from the projector 233 is guided to the measurement optical system 231 via the light projecting optical fiber 232 and is emitted downward from the measurement optical system 231 in the vertical direction. Light emitted downward from the measurement optical system 231 is irradiated onto the surface of the semiconductor wafer W when the semiconductor wafer W is supported on the rotary table 133.

  The light that reaches the surface of the semiconductor wafer W is reflected upward in the vertical direction, and the reflected light is incident on the measurement optical system 231 again. Then, the light incident on the measurement optical system 231 is guided to the spectroscope 235 via the light receiving optical fiber 234, undergoes spectral decomposition processing by the spectroscope 235, and the signal output from the spectroscope 235 as a result of this processing is controlled. Part 3 is input. The controller 3 calculates the reflectance of the semiconductor wafer W based on the reflected light intensity of the semiconductor wafer W obtained from the signal output from the spectroscope 235 and the intensity of the light emitted from the projector 233.

  In addition to the components described above, the alignment unit 130 includes a detection head for detecting a notch (notch for a φ300 mm wafer, orientation flat for a φ200 mm wafer) of the semiconductor wafer W supported by the rotary table 133 and rotating. A gas supply unit that supplies nitrogen gas to the chamber 131, an exhaust unit that exhausts atmospheric gas in the chamber 131, and the like (both not shown) are provided.

<1-4. Configuration of control unit>
Next, the configuration of the control unit 3 will be described. The control unit 3 controls the various operation mechanisms provided in the heat treatment apparatus 100. FIG. 9 is a diagram illustrating a hardware configuration of the control unit 3. 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 31 that performs various arithmetic processes, a ROM 32 that is a read-only memory that stores basic programs, a RAM 33 that is a readable / writable memory that stores various information, control software, data, and the like. The magnetic disk 34 to be placed is connected to a bus line 39.

  Further, the bus line 39 includes a motor 40 of the holding unit lifting mechanism 4 that lifts and lowers the holding unit 7 in the chamber 6, a lamp power source 99 that supplies power to the flash lamp FL, and zones 711 to 716 of the hot plate 71. The plate power source 98 that supplies power, and the projector 233 and the spectroscope 235 of the optical measurement unit 230 are electrically connected. The CPU 31 of the control unit 3 executes the control software stored in the magnetic disk 34 to control each of these operation mechanisms, and proceeds with the heat treatment of the semiconductor wafer W. Further, the magnetic disk 34 stores a correlation table 38 in which the reflectance of the semiconductor wafer W and the height position of the holding unit 7 are associated with each other, and the CPU 31 performs flash light irradiation based on the correlation table 38. The holding part 7 is moved up and down.

  Further, the display unit 35 and the input unit 36 are electrically connected to the bus line 39. The display unit 35 is configured by using, for example, a liquid crystal display and displays various information such as processing results and recipe contents. The input unit 36 is configured using, for example, a keyboard, a mouse, and the like, and receives input of commands, parameters, and the like. The operator of the apparatus can input commands and parameters from the input unit 36 while confirming the contents displayed on the display unit 35. The display unit 35 and the input unit 36 may be integrated to form a touch panel.

<2. Processing operation of heat treatment equipment>
Next, the processing operation of the semiconductor wafer W by the heat treatment apparatus 100 according to the present invention will be described. A semiconductor wafer W to be processed in the heat treatment apparatus 100 is a semiconductor wafer to which impurities (ions) are added by ion implantation after pattern formation. The activation of the impurities is performed by flash light irradiation heat treatment (annealing) by the flash heating unit 160. Here, the processing operation in the entire heat treatment apparatus 100 will be briefly described, and then the height adjustment of the holding unit 7 before the flash light irradiation will be described. The processing procedure of the heat treatment apparatus 100 described below proceeds by the control unit 3 controlling each operation mechanism of the heat treatment apparatus 100.

  FIG. 10 is a flowchart showing a processing procedure in the heat treatment apparatus 100. In the heat treatment apparatus 100, first, a plurality of semiconductor wafers W after impurity implantation are placed on the load port 110 of the indexer unit 101 in a state where a plurality of semiconductor wafers W are accommodated in the carrier C. Then, the delivery robot 120 takes out the semiconductor wafers W one by one from the carrier C and places them on the alignment unit 130. The alignment unit 130 positions the semiconductor wafer W by optically detecting notches and the like by rotating the semiconductor wafer W supported on the rotary table 133 around the vertical axis with the central portion as a rotation center.

  Moreover, in the alignment part 130, the reflectance measurement of the surface of the semiconductor wafer W by the optical measurement unit 230 is performed (step S1). Specifically, the intensity of incident light incident on the surface of the semiconductor wafer W from the projector 233 via the measurement optical system 231 and the intensity of reflected light reflected by the surface of the semiconductor wafer W and received by the measurement optical system 231. Is calculated by the control unit 3 and stored in the RAM 33 or the like as the reflectance of the surface of the semiconductor wafer W. The “front surface” of the semiconductor wafer W is a surface of the main surface of the semiconductor wafer W on which a pattern is formed and impurities are implanted, and the “back surface” is a surface of the main surface opposite to the front surface. It is.

  The semiconductor wafer W positioned by the alignment unit 130 is taken out into the transfer chamber 170 by the transfer arm 151 a on the upper side of the transfer robot 150, and turns so that the transfer robot 150 faces the flash heating unit 160. When the transfer robot 150 faces the flash heating unit 160, the lower transfer arm 151b takes out the preceding semiconductor wafer W after the flash heating process from the flash heating unit 160, and the upper transfer arm 151a removes the unprocessed semiconductor wafer W. It is carried into the flash heating unit 160. At this time, the transfer robot 150 slides the transfer arms 151a and 151b perpendicularly to the longitudinal direction of the flash lamp FL.

  In the flash heating unit 160, prior to processing, the holding unit 7 is lowered from the processing position shown in FIG. 7 to the delivery position shown in FIG. 3 (step S2). The “processing position” is the position of the holding unit 7 when the semiconductor wafer W is irradiated with flash 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 in the chamber 6 of the holding unit 7 shown in FIG. The “processing position” is not a fixed position above the “delivery position” but any position within a certain range in the vertical direction. The reference position of the holding unit 7 in the flash heating unit 160 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 when the processing is started. As shown in FIG. 3, when the holding unit 7 is lowered to the delivery position, the holding unit 7 comes close to the chamber bottom 62, and the tip of the support pin 70 penetrates the holding unit 7 and protrudes above the holding unit 7.

  Next, after the holding unit 7 is lowered to the delivery position, the valve 82 is opened, and an inert gas (in this embodiment, nitrogen gas) is supplied into the heat treatment space 65 of the chamber 6. At the same time, the valve 87 is opened and the gas in the heat treatment space 65 is exhausted (step S3). The purge amount of nitrogen gas into the chamber 6 when the semiconductor wafer W is loaded is about 40 liters / minute, and the nitrogen gas supplied to the chamber 6 is sent from the gas introduction buffer 83 to the arrow shown in FIG. It flows in the direction of AR4 and is exhausted by utility exhaust via the discharge path 86 and the valve 87. 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.

  Subsequently, the gate valve 185 is opened and the transfer opening 66 is opened. At this time, the transfer robot 150 moves the transfer arm 151 a holding the semiconductor wafer W to be processed into the chamber 6 from the transfer opening 66. The transfer robot 150 advances the transfer arm 151a to above the three support pins 70, and then slightly lowers the transfer arm 151a. At this time, the semiconductor wafer W held on the transfer arm 151a is transferred to the three support pins 70 (step S4).

  When the semiconductor wafer W is loaded into the chamber 6 and placed on the three support pins 70, the transfer robot 150 moves the transfer arm 151 a out of the chamber 6. Then, after the transfer opening 66 is closed by the gate valve 185, the holding unit 7 is raised from the delivery position to a predetermined processing position close to the chamber window 61 by the holding unit lifting mechanism 4 (step S5). At this time, the holding unit 7 moves up to a height position corresponding to the surface reflectance of the semiconductor wafer W measured in step S1 under the control of the control unit 3. This will be described later.

  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 is raised to the processing position, the semiconductor wafer W held by the susceptor 72 is also held at the processing position.

  Each of the six zones 711 to 716 of the hot plate 71 is heated to a predetermined temperature by a heater (resistive heating wire 76) individually incorporated in each zone (between the upper plate 73 and the lower plate 74). ing. When the holding unit 7 rises to the processing position and the semiconductor wafer W comes into contact with the holding unit 7, the semiconductor wafer W is preheated by the heater built in the hot plate 71 and the temperature gradually rises (step S6). .

  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 700 ° C., preferably about 350 ° C. to 600 ° C. (500 ° C. in the present embodiment) at which impurities added to the semiconductor wafer W do not 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 (step S7). At this time, a part of the flash light emitted from the flash lamp FL goes directly to the holding part 7 in the chamber 6, and the other part is once reflected by the reflector 52 and then goes into the chamber 6. Flash heating of the semiconductor wafer W is performed by irradiation of the flash light. Since the flash heating is performed by flash irradiation from the flash lamp FL, the surface temperature of the semiconductor wafer W can be increased in a short time.

  That is, the flash light irradiated from the flash lamp FL of the lamp house 5 is converted into a light pulse having a very short electrostatic energy stored in advance, and the irradiation time is about 0.1 milliseconds to 100 milliseconds. It is a very short and strong flash. Then, the surface temperature of the semiconductor wafer W that is flash-heated by flash light irradiation from the flash lamp FL instantaneously rises to a processing temperature T2 of 1000 ° C. or more, and the impurities injected into the semiconductor wafer W are activated. Later, the surface temperature drops rapidly. As described above, in the heat treatment apparatus 1, the surface temperature of the semiconductor wafer W can be raised and lowered in a very short time, so that the impurities are activated while suppressing diffusion of the impurities injected into the semiconductor wafer W due to heat. Can do. Since the time required for the activation of impurities is extremely short compared to the time required for the thermal diffusion, the activation is possible even in a short time in which diffusion of about 0.1 millisecond to 100 millisecond does not occur. Complete.

  After the 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. 3 by the holding unit lifting mechanism 4, and the semiconductor wafer W is transferred from the holding unit 7 to the support pins 70. (Step S8). Subsequently, the transfer opening 66 closed by the gate valve 185 is opened, and the transfer robot 150 causes the transfer arm 151 b to enter the chamber 6 through the transfer opening 66. The transfer robot 150 advances the transfer arm 151b to below the semiconductor wafer W supported by the three support pins 70, and then raises the transfer arm 151b. As a result, the semiconductor wafer W placed on the support pins 70 is transferred to the transfer arm 151b. Thereafter, the transfer robot 150 moves the transfer arm 151b supporting the semiconductor wafer W after the flash heat treatment out of the chamber 6 and unloads the semiconductor wafer W (step S9).

  As described above, nitrogen gas is continuously supplied to the chamber 6 during the heat treatment of the semiconductor wafer W in the flash heating unit 160, and the supply amount is about 30 liters / second 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.

  Thereafter, the transfer robot 150 turns to face the cooling unit 140, and the lower transfer arm 151 b places the semiconductor wafer W that has been subjected to the flash heat treatment in the cooling unit 140. The semiconductor wafer W cooled by the cooling unit 140 is returned to the carrier C by the delivery robot 120. The carrier C containing the predetermined number of processed semiconductor wafers W is unloaded from the load port 110 of the indexer unit 101, and a series of processes in the heat treatment apparatus 100 is completed.

  In the present embodiment, when the holding unit 7 is raised to the processing position in step S5, it is controlled to rise to a height position corresponding to the surface reflectance of the semiconductor wafer W. Hereinafter, this content will be described in detail.

  11 and 12 are diagrams schematically showing the behavior of multiple reflection during flash light irradiation. FIG. 11 shows a case where the surface reflectance of the semiconductor wafer W is high, and FIG. 12 shows a case where the surface reflectance is low. The height position of the semiconductor wafer W in FIGS. 11 and 12 is the same.

  In general, the surface reflectance of a semiconductor wafer W (blanket wafer) in which no pattern is formed on the surface and no film is formed is high. Moreover, the surface reflectance of the semiconductor wafer W on which a highly reflective film is formed on the surface is also high. When flash light is emitted from the flash lamp FL in a state where the holding unit 7 holding the semiconductor wafer W having such a high surface reflectance is raised to a predetermined processing position, as shown in FIG. Multiple reflection of flash light occurs between the held semiconductor wafer W at the processing position and the reflector 52 of the lamp house 5. That is, the flash light emitted from the flash lamp FL near the center in the arrangement of the plurality of flash lamps FL is reflected by the surface of the semiconductor wafer W having high reflectivity and travels toward the lamp house 5, and the reflected light is reflected by the reflector 52. The phenomenon of being reflected and incident again on the semiconductor wafer W and reflected is repeated.

  Further, flash light emitted from the flash lamps FL in the vicinity of the end portion in the arrangement of the plurality of flash lamps FL is a member provided in the chamber 6 (in this embodiment, the clamp ring 90, the holding unit 7 and the like), the reflector 52, and the like. After being subjected to multiple reflections, the light enters the peripheral edge of the semiconductor wafer W. Due to the multiple reflection of the flash light emitted from the flash lamps FL near the center and near the end, the intensity of the flash light irradiated at both the central portion and the peripheral portion of the surface of the semiconductor wafer W is increased.

  On the other hand, the surface reflectance of the semiconductor wafer W in which various films are formed on the surface and patterned is relatively low. Usually, the semiconductor wafer W actually to be processed is such a wafer, and the surface reflectance is lower than that of the blanket wafer. When flash light is emitted from the flash lamp FL in a state where the holding unit 7 holding the semiconductor wafer W having such a low surface reflectance is raised to a predetermined processing position, as shown in FIG. Reflection on the surface is unlikely to occur. Therefore, the flash light emitted from the flash lamp FL near the center in the arrangement of the plurality of flash lamps FL is hardly reflected on the surface of the semiconductor wafer W, and the attenuation of the multiple reflection is increased.

  Further, the flash light emitted from the flash lamps FL in the vicinity of the end in the arrangement of the plurality of flash lamps FL is multiple-reflected between the member provided in the chamber 6 and the reflector 52, as in FIG. After that, the light enters the peripheral edge of the semiconductor wafer W. That is, since multiple reflection hardly occurs at the central portion of the semiconductor wafer W, incidence due to multiple reflection is reduced, while incidence due to multiple reflection at elements other than the semiconductor wafer W occurs at the peripheral portion. Such multiple reflections by elements other than the semiconductor wafer W occur without depending on the surface reflectance of the semiconductor wafer W, and the semiconductor wafer W has a substantially constant intensity on the peripheral edge of the semiconductor wafer W regardless of the surface reflectance. Incident. As a result, the intensity of the flash light irradiated to the peripheral portion is relatively stronger than the central portion of the semiconductor wafer W, and the temperature of the peripheral portion during flash heating is relatively higher than the central portion.

  As described above, the in-plane distribution of the intensity of the flash light irradiated varies due to the behavior of multiple reflections depending on the reflectance of the surface of the semiconductor wafer W. If the height position of the semiconductor wafer W at the time of flash light irradiation is the same, when the surface reflectance of the semiconductor wafer W becomes lower, the intensity of the flash light irradiated to the peripheral portion becomes relatively stronger than the central portion, and the temperature Is also relatively high. For this reason, even if the intensity of the flash lamp FL and the preheating temperature of the hot plate 71 are adjusted using a blanket wafer having a high surface reflectance so that the in-plane temperature distribution is uniform, the surface reflectance is lower than that. When flash light irradiation is actually performed on the semiconductor wafer W to be processed, there has been a problem that the temperature of the peripheral portion becomes higher than that of the central portion. On the contrary, when the surface reflectance of the semiconductor wafer W is increased, the temperature of the peripheral portion may be relatively lower than that of the central portion.

  Therefore, in the present embodiment, the height position of the semiconductor wafer W at the time of flash light irradiation is adjusted according to the surface reflectance of the semiconductor wafer W. 13 and 14 are diagrams for explaining the correlation between the height position of the holding unit 7 holding the semiconductor wafer W and the flash light intensity. As described above, the plurality of flash lamps FL are arranged above the chamber 6 over a wider area than the optical window 67 of the chamber 6. For this reason, as shown in FIGS. 13 and 14, when flash light is irradiated from a plurality of flash lamps FL, a shadow region is formed by the light emitting region outside the optical window 67 and the inner peripheral tip of the clamp ring 90. It is formed. In FIGS. 13 and 14, such a shadow region is indicated by a hatched portion.

  As shown in FIG. 13, when the holding part 7 holding the semiconductor wafer W is raised to a relatively high position (position where the distance from the optical window 67 is short), the area of the shadow region at that height position is small. That is, the shadow area formed on the peripheral edge portion of the surface of the semiconductor wafer W is also small (in the example of FIG. 13, the shadow area is formed outside the wafer edge). On the other hand, as shown in FIG. 14, when the holding unit 7 holding the semiconductor wafer W is lowered to a relatively low position (a position where the distance from the optical window 67 is long), the shadow region at the height position is reduced. The area is large. That is, the shadow area formed on the peripheral edge of the surface of the semiconductor wafer W is also large.

  Accordingly, when the holding unit 7 that holds the semiconductor wafer W is raised, the shadow area formed on the peripheral edge of the semiconductor wafer W by the chamber 6 (specifically, the inner peripheral tip of the clamp ring 90) during flash light irradiation is reduced. On the contrary, when descending, the shadow area formed on the peripheral edge of the semiconductor wafer W becomes larger. As a result, when the holding unit 7 is raised, the intensity of the flash light reaching the peripheral edge of the semiconductor wafer W during flash light irradiation is increased, and conversely, when the holding unit 7 is lowered, the flash light reaching the peripheral edge of the semiconductor wafer W is increased. Strength will decrease. Note that even if a shadow region is formed at the peripheral edge, the intensity of the flash light does not become zero, and there is direct light from a flash lamp FL other than the flash lamp FL that contributed to shadow formation or light incident by multiple reflection. Therefore, the flash light intensity is only relatively lowered.

  By raising and lowering the holding unit 7 holding the semiconductor wafer W in this way, the intensity of the flash light reaching the peripheral edge of the semiconductor wafer W during flash light irradiation is increased and decreased, and the temperature distribution in the wafer surface is adjusted. Can do. FIG. 15 is a diagram showing a change in the in-plane temperature distribution of the semiconductor wafer W due to the raising and lowering of the holding unit 7. When the holding unit 7 is positioned at the relatively high processing position H1, the shadow area formed on the peripheral edge of the semiconductor wafer W during flash light irradiation is reduced, and the intensity of the flash light reaching the peripheral edge is increased. And the temperature of the said peripheral part becomes higher than a center part. Further, when the holding unit 7 is positioned at the relatively low processing position H3, the shadow area formed on the peripheral part of the semiconductor wafer W during the flash light irradiation becomes large, and the intensity of the flash light reaching the peripheral part Decreases, and the temperature of the peripheral portion becomes lower than that of the central portion. At any height of the processing position, the in-plane temperature distribution of the semiconductor wafer W is not uniform and is not preferable.

  On the other hand, when the holding unit 7 is positioned at the processing position H2 that is the height between the processing position H1 and the processing position H3, the intensity of the flash light that reaches the peripheral edge of the semiconductor wafer W during flash light irradiation is appropriate. Value, and the in-plane temperature distribution of the semiconductor wafer W becomes uniform. Such a processing position H2 is caused by the influence of the multiple reflection at the time of the flash light irradiation described above, the influence of the reflection by the member such as the clamp ring 90 provided in the chamber 6, and the reduction of the flash light intensity due to the formation of the shadow region. It is defined by the balance with the impact. That is, the height of the processing position H2 at which the in-plane temperature distribution is uniform depends on the reflectance of the surface of the semiconductor wafer W, and the height of the processing position H2 is different if the reflectance is different.

  As described above, if the height position of the semiconductor wafer W at the time of flash light irradiation is the same (that is, if the influence by the shadow region is the same), the lower the surface reflectance of the semiconductor wafer W, the closer to the peripheral portion. The intensity of the irradiated flash light is relatively stronger than the central portion, and the peripheral temperature is also relatively high. Accordingly, the lower the surface reflectance of the semiconductor wafer W is, the lower the holding unit 7 is lowered, and the shadow area formed at the peripheral edge during flash light irradiation is enlarged, and the intensity of flash light irradiation reaching the peripheral edge is reduced. An appropriate processing position H2 where the in-plane temperature distribution is uniform exists relatively below. Conversely, as the surface reflectance of the semiconductor wafer W increases, the holding unit 7 is raised upward to reduce the shadow area formed at the peripheral edge during flash light irradiation, and the intensity of flash light irradiation reaching the peripheral edge is reduced. The processing position H2 where the in-plane temperature distribution is uniform is present relatively above.

  In the present embodiment, the correlation table 38 is created and controlled by associating the reflectance of the surface of the semiconductor wafer W with the appropriate height position (processing position H2) of the holding unit 7 where the in-plane temperature distribution is uniform. The data is stored in the magnetic disk 34 of the unit 3. FIG. 16 is a diagram illustrating an example of the correlation table 38. For a plurality of semiconductor wafers W having different surface reflectivities, the height position of the holding unit 7 where the in-plane temperature distribution at the time of flash light irradiation is uniform is obtained in advance by experiment or simulation, and FIG. A correlation table 38 as shown can be created and stored on the magnetic disk 34. As shown in the drawing, the lower the reflectance of the surface of the semiconductor wafer W, the lower the height position of the holding unit 7 where the in-plane temperature distribution becomes uniform. The plurality of semiconductor wafers W having different surface reflectances can be prepared by depositing light absorption films with different thicknesses on the surface of the blanket wafer.

  When the holding unit 7 is raised to the processing position before the flash light irradiation in step S5 of FIG. 10, the control unit 3 reflects the reflectance of the surface of the semiconductor wafer W measured in step S1 based on the correlation table 38. The motor 40 of the holding unit elevating mechanism 4 is controlled so that the holding unit 7 rises to a height position corresponding to. Accordingly, if the surface reflectance of the semiconductor wafer W measured by the optical measurement unit 230 in step S1 is increased, the holding unit 7 is raised to a higher processing position in step S5, and the semiconductor wafer W is caused by the chamber 6 during flash light irradiation. The shadow area formed on the peripheral edge of the flash is reduced, and the intensity of the flash light reaching the peripheral edge is increased. Conversely, if the surface reflectance of the semiconductor wafer W measured in step S1 is low, the holding unit 7 is raised to a lower processing position in step S5 (lower than the processing position when the reflectance is high). The shadow area formed on the peripheral edge of the semiconductor wafer W by the chamber 6 at the time of flash light irradiation is enlarged, and the intensity of the flash light reaching the peripheral edge is reduced.

  As described above, the holding unit 7 is moved up and down in accordance with the reflectance of the surface of the semiconductor wafer W, and the intensity of the flash light reaching the peripheral edge of the semiconductor wafer W at the time of flash light irradiation is adjusted. The in-plane temperature distribution can be made uniform.

<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 above embodiment, the reflectance of the surface of the semiconductor wafer W is measured by the alignment unit 130, but the present invention is not limited to this, and the semiconductor wafer W is transferred from the indexer unit 101 to the flash heating unit 160. The optical measurement unit 230 may be provided anywhere on the transport path to perform reflectance measurement. Further, the surface reflectance of the semiconductor wafer W may be measured by the flash heating unit 160, and the processing position of the holding unit 7 may be determined according to the measurement result.

  In addition, the surface reflectance of the semiconductor wafer W is measured in advance by an apparatus separate from the heat treatment apparatus 100, and the measured value is transmitted to the heat treatment apparatus 100 side to determine the processing position of the holding unit 7. May be. Furthermore, if the processing of a lot including a plurality of semiconductor wafers W having the same pattern formation and film formation is performed, the surface reflectance of the plurality of semiconductor wafers W is the same. The processing position of the holding unit 7 may be determined without performing sequential reflectance measurement with one surface reflectance as a fixed value.

  Moreover, in the said embodiment, the intensity | strength of the flash light which reaches | attains the said peripheral part is adjusted by raising / lowering the holding | maintenance part 7 and changing the magnitude | size of the shadow area | region formed in the peripheral part of the semiconductor wafer W. However, the present invention is not limited to this, and the arrangement of the plurality of flash lamps FL may be raised and lowered instead of or in addition to raising and lowering the holding unit 7. Alternatively, the height of the side wall of the chamber 6 may be made variable, and the height may be adjusted to change the size of the shadow region formed on the peripheral edge of the semiconductor wafer W during flash light irradiation. Furthermore, a light shielding member that expands and contracts along the horizontal direction may be provided inside the side wall of the chamber 6 so that the size of the shadow region formed on the peripheral edge of the semiconductor wafer W during flash light irradiation may be changed. .

  In short, any structure may be used as long as it adjusts the size of the shadow area formed at the peripheral edge of the semiconductor wafer W according to the surface reflectance of the semiconductor wafer W and adjusts the intensity of the flash light reaching the peripheral edge. .

  Further, in the above embodiment, the front surface of the semiconductor wafer W is irradiated with flash light to perform the heat treatment, but the back surface of the semiconductor wafer W may be irradiated with flash light. Specifically, the same processing as in the above embodiment may be performed by inverting the front and back of the semiconductor wafer W and holding it on the holding unit 7 (that is, holding the surface as the lower surface). In this case, the flashlight that reaches the peripheral portion by moving up and down the holding portion 7 according to the reflectance of the back surface of the semiconductor wafer W and adjusting the size of the shadow region formed on the peripheral portion of the back surface when the flash light is irradiated. What is necessary is just to adjust the intensity.

  In the above embodiment, the semiconductor wafer W is preheated by placing it on the hot plate 71. However, the preheating method is not limited to this, and a halogen lamp is provided to provide light. The semiconductor wafer W may be preheated to the preheating temperature T1 by irradiation. Even in this case, the size of the shadow region formed on the peripheral edge of the semiconductor wafer W during flash light irradiation is changed by raising and lowering the holding member that holds the semiconductor wafer W as in the above embodiment. Thus, the intensity of the flash light reaching the peripheral edge can be adjusted.

  Also, the upper transfer arm 151a of the transfer robot 150 is designed as a dedicated arm for holding the unprocessed semiconductor wafer W, and the lower transfer arm 151b is designed as a dedicated arm for holding the processed semiconductor wafer W. Thus, the transport robot 150 can be reduced in size and transport reliability can be improved.

  The substrate to be processed by the heat treatment technique according to the present invention is not limited to a semiconductor wafer, and may be a glass substrate or a solar cell substrate used for a liquid crystal display device or the like. Further, the technique according to the present invention may be applied to bonding of metal and silicon or crystallization of polysilicon.

DESCRIPTION OF SYMBOLS 3 Control part 4 Holding part raising / lowering mechanism 5 Lamphouse 6 Chamber 7 Holding part 31 CPU
34 Magnetic disk 38 Correlation table 40 Motor 52 Reflector 61 Chamber window 63 Chamber side 67 Optical window 71 Hot plate 72 Susceptor 90 Clamp ring 100 Heat treatment apparatus 101 Indexer part 130 Alignment part 140 Cooling part 150 Transport robot 160 Flash heating part 170 Transport chamber 230 Optical measurement unit 231 Measurement optical system 233 Projector 235 Spectrometer FL Flash lamp W Semiconductor wafer

Claims (10)

A heat treatment apparatus for heating a substrate by irradiating the substrate with flash light,
A chamber for housing the substrate;
Holding means for holding the substrate in the chamber;
A flash lamp for irradiating flash light on one surface of the substrate held by the holding means;
Intensity adjusting means for adjusting the intensity of flash light reaching the peripheral edge of the substrate according to the reflectance of the one surface;
A heat treatment apparatus comprising: The heat treatment apparatus according to claim 1, wherein
The intensity adjusting means increases the intensity of flash light reaching the peripheral portion when the reflectance of the one surface increases, and the intensity of flash light reaching the peripheral portion when the reflectance of the one surface decreases. A heat treatment apparatus characterized by reducing the amount of heat. The heat treatment apparatus according to claim 2,
The flash lamp is disposed above the chamber in a region wider than the optical window of the chamber,
The strength adjusting means includes elevating means for elevating and lowering the holding means in the chamber,
The raising / lowering means raises the holding means when the reflectance of the one surface becomes high, and reduces the shadow area formed on the peripheral edge of the substrate by the chamber during flash light irradiation, and the reflectance of the one surface The heat treatment apparatus is characterized in that the shadow area is enlarged by lowering the holding means when the temperature becomes low. The heat treatment apparatus according to claim 3, wherein
The strength adjusting means holds a correlation table in which the reflectance of the one surface and the height position of the holding means are associated with each other, and moves the holding means up and down based on the correlation table . In the heat processing apparatus in any one of Claims 1-4,
A heat treatment apparatus, further comprising reflectance measuring means for measuring the reflectance of the one surface. A heat treatment method for heating a substrate by irradiating the substrate with flash light,
A flash light irradiation step of irradiating flash light from a flash lamp on one side of the substrate held by the holding means in the chamber;
An intensity adjustment step of adjusting the intensity of flash light reaching the peripheral edge of the substrate according to the reflectance of the one surface;
A heat treatment method comprising: The heat treatment method according to claim 6, wherein
In the intensity adjusting step, if the reflectance of the one surface increases, the intensity of the flash light reaching the peripheral portion increases, and if the reflectance of the one surface decreases, the intensity of the flash light reaching the peripheral portion. The heat processing method characterized by reducing. The heat treatment method according to claim 7,
The flash lamp is disposed above the chamber in a region wider than the optical window of the chamber,
In the intensity adjustment step, if the reflectance of the one surface increases, the holding means is raised to reduce the shadow area formed on the peripheral edge of the substrate by the chamber during flash light irradiation, and the reflection of the one surface A heat treatment method, wherein the shadow area is enlarged by lowering the holding means when the rate decreases. The heat treatment method according to claim 8, wherein
In the intensity adjustment step, the holding means is moved up and down based on a correlation table in which the reflectance of the one surface and the height position of the holding means are associated with each other. In the heat treatment method according to any one of claims 6 to 9,
A heat treatment method, further comprising a reflectance measurement step of measuring the reflectance of the one surface.

Images