JP2005085993A - Heat treatment device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat treatment device and method for heating a substrate by a hot plate by preventing the substrate from being bent. <P>SOLUTION: A hot plate 90 is stopped in thirty seconds at a proximity heating position H2 where the upper surface of the preliminarily heated hot plate 90 and a semiconductor wafer W supported by a support pin 70 are put in a non-contact proximity status. The semiconductor wafer W supported by the support pin 70 is gradually heated by radiation heat from the hot plate 90 during that time so that the temperature of the semiconductor wafer W can be smoothly increased. Afterwards, the hot plate 90 is further ascended, and a semiconductor wafer W is directly placed on the hot plate 90. Therefore, the temperature of the semiconductor wafer W is smoothly increased by proximity heating, and then the semiconductor wafer W is rapidly heated. Thus, it is possible to prevent the semiconductor wafer W from being given rapid temperature change, and to preliminarily heat the semiconductor wafer W by the hot plate 90 without generating any bend in the semiconductor wafer W. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat treatment apparatus for placing and heating a semiconductor wafer, a glass substrate or the like (hereinafter simply referred to as “substrate”), and more particularly, to a heat treatment apparatus and a heat treatment method for preheating a substrate before flash heating.

  In the manufacturing process of a semiconductor wafer or the like, various heat treatments are performed for various purposes. Conventionally, as a heat treatment, a semiconductor wafer is generally placed on a hot plate with a built-in heater and heated. Although this method can stably and uniformly heat the semiconductor wafer to the target temperature, there is a problem that the wafer is likely to warp when the normal temperature semiconductor wafer W is placed on a high temperature hot plate.

  For this reason, for example, in the CVD apparatus of Patent Document 1, a technique for preheating the wafer by holding the wafer with a support pin at a position close to the hot plate has been proposed. Further, for example, the ashing apparatus disclosed in Patent Document 2 also employs a preheating method in a state where the substrate and the hot plate are brought close to each other.

  By the way, heat treatment is also performed in the ion activation step of the semiconductor wafer after ion implantation. The heat treatment in the ion activation process is performed by heating (annealing) the semiconductor wafer to a temperature of, for example, about 1000 ° C. to 1100 ° C., and conventionally uses the energy of light emitted from the halogen lamp. For example, a lamp annealing apparatus that raises the temperature of a wafer at a speed of several hundred degrees per second has been used.

  However, even when ion activation of a semiconductor wafer is performed using a heat treatment apparatus that raises the temperature of the semiconductor wafer at a rate of several hundred degrees per second by a halogen lamp, the profile of ions implanted into the semiconductor wafer is reduced. That is, it has been found that a phenomenon occurs in which ions diffuse due to heat. When such a phenomenon occurs, even if ions are implanted at a high concentration on the surface of the semiconductor wafer, the ions after implantation are diffused, so that ions must be implanted more than necessary. Has occurred.

  In order to solve the above-mentioned ion diffusion problem, the surface of the semiconductor wafer is irradiated with flash light using a xenon flash lamp or the like, so that only the surface of the semiconductor wafer into which ions are implanted is extremely short (less than a few milliseconds). ) Has been proposed (see, for example, Patent Documents 3 and 4). If the temperature is raised for a very short time with a xenon flash lamp, there is not enough time for ions to diffuse, so only ion activation is performed without the profile of the ions implanted in the semiconductor wafer being distorted. Can do it.

JP 2003-77863 A Japanese Patent Laid-Open No. 11-8227 JP 59-169125 A JP 63-166219 A

  In such a flash lamp annealing apparatus, a target temperature of about 1000 ° C. to 1100 ° C. cannot be reached by flash irradiation with a xenon flash lamp alone. Therefore, the semiconductor wafer is heated to a certain temperature (ion diffusion occurs before flash irradiation). Preheating treatment is performed in which the temperature is raised to a temperature that is not present. Since the preheating treatment is mainly performed in a temperature range of about 400 ° C. to 500 ° C., it is mainly performed by a hot plate method excellent in heat uniformity and controllability.

  However, when a room temperature semiconductor wafer is placed on and brought into contact with a high temperature hot plate of about 400 ° C. to 500 ° C., a rapid temperature change occurs in the wafer surface, and the in-plane uniformity of the temperature distribution is instantaneously large. Variations occurred and the semiconductor wafer was warped. If the semiconductor wafer is warped, it will cause damage to the wafer, such as slipping. As a result, there will be a large in-plane variation in the processing result of the flash heating process, and in the worst case, there will be a problem that the wafer cracks during flash heating. .

  The present invention has been made in view of the above problems, and an object thereof is to provide a heat treatment apparatus and a heat treatment method capable of heating a substrate with a hot plate without causing warpage of the substrate.

  In order to solve the above-mentioned problem, the invention of claim 1 is a heat treatment apparatus for heating a substrate, wherein a hot plate for placing and heating the substrate, a support pin capable of supporting the substrate above the hot plate, A relative elevating means for relatively moving the hot plate and the support pin up and down; and an elevating control means for controlling the relative elevating means to adjust the distance between the upper surface of the hot plate and the substrate supported by the support pin; The relative elevation means is controlled by the elevation control means so that the average temperature rise rate of the substrate heated by the hot plate is 11 ° C./sec or less.

  According to a second aspect of the present invention, in the heat treatment apparatus according to the first aspect of the present invention, the elevation control means has a position where the upper surface of the hot plate and the substrate supported by the support pins are in a non-contact proximity state. Then, the lifting / lowering movement is stopped for a predetermined time, and then the hot plate and the support pins are relatively moved up and down to control the relative lifting means so that the substrate is placed on the hot plate.

  The invention according to claim 3 is the heat treatment apparatus according to claim 1, wherein the raising / lowering control means raises / lowers the hot plate and the support pin relative to each other until the substrate is placed on the hot plate. The relative elevating means is controlled so that the moving speed becomes slower than the relative elevating movement speed after the substrate is placed on the hot plate.

  According to a fourth aspect of the present invention, in the heat treatment apparatus according to any one of the first to third aspects of the present invention, the substrate is further heated by irradiating a flash on the substrate preheated by the hot plate. It has a flash lamp.

  According to a fifth aspect of the present invention, in the heat treatment method for heating a substrate, a hot plate for placing and heating the substrate and a support pin for supporting the substrate above the hot plate are provided with an average temperature rise rate of the substrate. Is moved up and down relatively so as to be 11 ° C./sec or less.

  The invention according to claim 6 is the heat treatment method according to claim 5, wherein the hot plate is moved up and down for a predetermined time at a position where the upper surface of the hot plate and the substrate supported by the support pins are in a non-contact proximity state. Then, the hot plate and the support pins are moved up and down relatively to place the substrate on the hot plate.

  The invention of claim 7 is the heat treatment method according to the invention of claim 5, wherein the relative up-and-down movement speed of the hot plate and the support pin until the substrate is placed on the hot plate It is slower than the relative up-and-down movement speed after the substrate is placed on the plate.

  The invention of claim 8 is the heat treatment method according to any one of claims 5 to 7, wherein the substrate preheated by the hot plate is irradiated with flash light from a flash lamp. Is further provided with a step of heating.

  According to the first aspect of the present invention, since the average temperature rising rate of the substrate heated by the hot plate is set to 11 ° C./sec or less, it is possible to prevent the substrate from being subjected to a rapid temperature change. The substrate can be heated by the hot plate without causing warpage.

  According to the invention of claim 2, the up-and-down movement is stopped for a predetermined time at a position where the upper surface of the hot plate and the substrate supported by the support pins are in a non-contact proximity state, and then the hot plate and the support pins are Since the substrate is placed on the hot plate by being moved up and down relatively, it is possible to reliably prevent a sudden temperature change from occurring on the substrate and to prevent the substrate from being warped. Can be heated.

  According to the invention of claim 3, the relative up / down movement speed of the hot plate and the support pins until the substrate is placed on the hot plate is the relative up / down movement after the substrate is placed on the hot plate. Since the speed is made lower than the speed, it is possible to reliably prevent the substrate from undergoing a rapid temperature change, and the substrate can be heated by the hot plate without causing the substrate to warp.

  According to the invention of claim 4, since the flash lamp for further heating the substrate by irradiating flash light to the substrate preheated by the hot plate is provided, the substrate is warped during preheating. Can be prevented.

  According to the invention of claim 5, the hot plate for placing and heating the substrate and the support pins for supporting the substrate above the hot plate have an average heating rate of the substrate of 11 ° C./sec or less. Therefore, the substrate can be heated by the hot plate without causing a warp of the substrate without causing a sudden temperature change.

  According to the invention of claim 6, the elevation movement is stopped for a predetermined time at a position where the upper surface of the hot plate and the substrate supported by the support pins are in a non-contact proximity state, and then the hot plate and the support pins are moved. Since the substrate is placed on the hot plate by being moved up and down relatively, it is possible to reliably prevent the substrate from undergoing a rapid temperature change, and to heat the substrate by the hot plate without causing the substrate to warp. it can.

  According to the seventh aspect of the present invention, the relative up-and-down movement speed of the hot plate and the support pins until the substrate is placed on the hot plate is set as the relative up-and-down movement speed after the substrate is placed on the hot plate. Since the speed is lower than the speed, it is possible to reliably prevent the substrate from undergoing a rapid temperature change, and the substrate can be heated by the hot plate without causing the substrate to warp.

  According to the eighth aspect of the present invention, since the substrate is further heated by irradiating the flashlight from the flash lamp to the substrate preheated by the hot plate, the substrate is warped during the preheating. Can be prevented.

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

<1. First Embodiment>
1 and 2 are side sectional views showing the structure of a heat treatment apparatus according to the present invention. This heat treatment apparatus is an apparatus for performing heat treatment of a substrate such as a semiconductor wafer by flash light from a xenon flash lamp.

  This heat treatment apparatus includes a translucent plate 61, a bottom plate 62, and side plates 63 and 64 that form a cylindrical internal space, and includes a chamber 65 for housing and heat-treating the semiconductor wafer W therein. The translucent plate 61 constituting the upper part of the chamber 65 is made of, for example, a material having infrared transparency such as quartz, and functions as a chamber window that transmits light emitted from the light source 5 and guides it into the chamber 65. doing. The bottom plate 62 constituting the chamber 65 is provided with support pins 70 that pass through a susceptor 73 and a heating plate 74 described later and support the semiconductor wafer W from the lower surface thereof.

  Further, an opening 66 for carrying in and out the semiconductor wafer W is formed in the side plate 64 constituting the chamber 65. The opening 66 can be opened and closed by a gate valve 68 that rotates about a shaft 67. The semiconductor wafer W is loaded into the chamber 65 by a transfer robot (not shown) with the opening 66 opened. Further, when the semiconductor wafer W is heat-treated in the chamber 65, the opening 66 is closed by the gate valve 68.

  The chamber 65 is provided below the light source 5. The light source 5 includes a plurality (30 in the present embodiment) of xenon flash lamps 69 (hereinafter also simply referred to as “flash lamps 69”) and a reflector 71. The plurality of flash lamps 69 are rod-shaped lamps each having a long cylindrical shape, and are arranged in parallel with each other such that the longitudinal direction thereof is along the horizontal direction. The reflector 71 is disposed above the plurality of flash lamps 69 so as to cover them entirely.

  The xenon flash lamp 69 includes a glass tube in which xenon gas is sealed and an anode and a cathode connected to a capacitor at both ends thereof, and a trigger electrode wound around an external portion of the glass tube. Is provided. Since xenon gas is an electrical insulator, electricity does not flow into the glass tube under normal conditions. However, if 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, and the xenon gas is heated by Joule heat at that time, and light is emitted. . In the xenon flash lamp 69, the electrostatic energy stored in advance is converted into an extremely short light pulse of 0.1 millisecond to 10 millisecond. It has the feature that it can.

  A light diffusing plate 72 is disposed between the light source 5 and the translucent plate 61. As the light diffusion plate 72, a surface of quartz glass as an infrared transmitting material subjected to light diffusion processing is used.

  Part of the light emitted from the flash lamp 69 passes directly through the light diffusing plate 72 and the light transmitting plate 61 toward the chamber 65. Further, another part of the light emitted from the flash lamp 69 is once reflected by the reflector 71, then passes through the light diffusing plate 72 and the light transmitting plate 61 and goes into the chamber 65.

  A hot plate 90 is provided in the chamber 65. The hot plate 90 includes a heating plate 74 and a susceptor 73. The susceptor 73 is attached to the upper surface of the heating plate 74. Further, a misalignment prevention pin 75 of the semiconductor wafer W is attached to the surface of the susceptor 73. The semiconductor wafer W is directly held in a substantially horizontal posture by the susceptor 73 in the chamber 65.

  The heating plate 74 is for preheating (assist heating) the semiconductor wafer W. The heating plate 74 is made of aluminum nitride and has a configuration in which a heater and a sensor for controlling the heater are housed. On the other hand, the susceptor 73 is for positioning and holding the semiconductor wafer W, and for preheating the semiconductor wafer W uniformly by diffusing the thermal energy from the heating plate 74. As the material of the susceptor 73, a material having a relatively low thermal conductivity such as aluminum nitride or quartz is employed.

  The hot plate 90 is configured to move up and down between the loading / unloading position of the semiconductor wafer W shown in FIG. 1 and the heat treatment position of the semiconductor wafer W shown in FIG.

  That is, the heating plate 74 is connected to the moving plate 42 via the cylindrical body 41. The moving plate 42 can be moved up and down by being guided by a guide member 43 supported by a bottom plate 62 of the chamber 65. A fixed plate 44 is fixed to the lower end portion of the guide member 43, and a motor 40 that rotationally drives a ball screw 45 is disposed at the central portion of the fixed plate 44. The ball screw 45 is screwed with a nut 48 connected to the moving plate 42 via connecting members 46 and 47. Therefore, the hot plate 90 can be moved up and down between the loading / unloading position of the semiconductor wafer W shown in FIG. 1 and the heat treatment position of the semiconductor wafer W shown in FIG.

  The loading / unloading position of the semiconductor wafer W shown in FIG. 1 is placed on the support pin 70 by placing the semiconductor wafer W loaded from the opening 66 using a transfer robot (not shown). The hot plate 90 is lowered so that the finished semiconductor wafer W can be unloaded from the opening 66. That is, a through-hole is formed in the susceptor 73 and the heating plate 74 that can be raised and lowered, and a support pin 70 that is fixedly installed on the bottom plate 62 can be inserted into the susceptor 73 and the heating plate 74. . When the hot plate 90 is lowered to the carry-in / carry-out position, the upper end portion of the support pin 70 protrudes from the upper surface of the susceptor 73 and the semiconductor wafer W can be placed as shown in FIG.

  On the other hand, the heat treatment position of the semiconductor wafer W shown in FIG. 2 is a position where the hot plate 90 is raised above the upper ends of the support pins 70 in order to perform heat treatment on the semiconductor wafer W. When the hot plate 90 is moved up to the heat treatment position, the upper end portion of the support pin 70 becomes lower than the upper surface of the susceptor 73 as shown in FIG. 2, and the semiconductor wafer W placed on the support pin 70 is received by the susceptor 73. . That is, the motor 40 moves the hot plate 90 up and down relative to the support pins 70 between the loading / unloading position of the semiconductor wafer W shown in FIG. 1 and the heat treatment position of the semiconductor wafer W shown in FIG. It is.

  In the process in which the hot plate 90 is lowered from the heat treatment position of FIG. 2 to the loading / unloading position of FIG. 1, the semiconductor wafer W supported by the susceptor 73 is transferred to the support pins 70. On the contrary, in the process in which the hot plate 90 is raised from the loading / unloading position in FIG. 1 to the heat treatment position in FIG. 2, the semiconductor wafer W placed on the support pins 70 is received by the susceptor 73. It is supported by the surface of the liquid and rises, and is held in a horizontal posture at a position close to the translucent plate 61 in the chamber 65.

  In a state where the hot plate 90 supporting the semiconductor wafer W is raised to the heat treatment position, the translucent plate 61 is positioned between the semiconductor wafer W held on the hot plate 90 and the light source 5. Note that the distance between the susceptor 73 and the light source 5 at this time can be adjusted to an arbitrary value by controlling the rotation amount of the motor 40.

  Further, between the bottom plate 62 of the chamber 65 and the moving plate 42, a telescopic bellows 77 is disposed so as to surround the cylindrical body 41 and maintain the chamber 65 in an airtight body. When the hot plate 90 is raised to the heat treatment position, the bellows 77 contracts, and when the hot plate 90 is lowered to the loading / unloading position, the bellows 77 extends to block the atmosphere in the chamber 65 from the outside atmosphere.

  In the side plate 63 opposite to the opening 66 in the chamber 65, an introduction path 78 connected to the on-off valve 80 is formed. The introduction path 78 is for introducing a gas necessary for processing, for example, an inert nitrogen gas, into the chamber 65. On the other hand, a discharge passage 79 connected to the on-off valve 81 is formed in the opening 66 in the side plate 64. The discharge path 79 is for discharging the gas in the chamber 65, and is connected to an exhaust means (not shown) via the on-off valve 81.

  The heat treatment apparatus includes a controller 10 for controlling each mechanism unit such as the motor 40. FIG. 3 is a block diagram showing the configuration of the controller 10. The configuration of the controller 10 as hardware is the same as that of a general computer. That is, the controller 10 stores a CPU 11 that performs various arithmetic processes, a ROM 12 that is a read-only memory that stores basic programs, a RAM 13 that is a readable / writable memory that stores various information, control software, data, and the like. A magnetic disk 14 is connected to a bus line 19.

  The bus line 19 is electrically connected to a power supply circuit for the motor 40 of the heat treatment apparatus and a flash lamp 69 (not shown). The CPU 11 of the controller 10 executes the control software stored in the magnetic disk 14 to control the lighting timing of the flash lamp 69 and to control the motor 40 to adjust the height position of the hot plate 90.

  Further, a display unit 21 and an input unit 22 are electrically connected to the bus line 19. The display unit 21 is configured using, for example, a liquid crystal display or the like, and displays various information such as processing results and recipe contents. The input unit 22 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 22 while confirming the contents displayed on the display unit 21. Note that the display unit 21 and the input unit 22 may be integrated to form a touch panel.

  The controller 10 can move the hot plate 90 to any position between the carry-in / carry-out position and the heat treatment position by controlling the motor 40. FIG. 4 is a diagram illustrating a height position at which the hot plate 90 can move. As described above, the hot plate 90 can be moved up and down relative to the support pins 70 between the carry-in / carry-out position H1 and the heat treatment position H4 of the semiconductor wafer W. The loading / unloading position H <b> 1 of the semiconductor wafer W is a position where the hot plate 90 is lowered from the upper end portion of the support pins 70 so that the semiconductor wafer W can be delivered to the support pins 70. Further, the heat treatment position H <b> 4 is a position where the hot plate 90 is raised above the upper end of the support pins 70 in order to perform the flash heat treatment on the semiconductor wafer W.

  When the controller 10 controls the motor 40, the hot plate 90 can also move to the proximity heating position H2 and the delivery position H3 between the loading / unloading position H1 and the heat treatment position H4. The proximity heating position H2 is a position where the upper surface (susceptor 73) of the hot plate 90 and the semiconductor wafer W supported by the support pins 70 are in a non-contact proximity state. When the hot plate 90 is located at the proximity heating position H2, the semiconductor wafer W supported by the support pins 70 is gently heated by the radiant heat from the hot plate 90. On the other hand, the delivery position H3 is a position where the semiconductor wafer W is delivered between the hot plate 90 and the support pins 70, that is, the height position of the upper end of the support pins 70.

  Next, the heat treatment operation of the semiconductor wafer W by the heat treatment apparatus according to the present invention will be described. A semiconductor wafer W to be processed in this heat treatment apparatus is a semiconductor wafer after ion implantation. Further, the following processing is executed when each mechanism unit such as the motor 40 is driven in accordance with an instruction from the controller 10.

  In this heat treatment apparatus, the semiconductor wafer W is carried in through the opening 66 by a transfer robot (not shown) in a state where the hot plate 90 is disposed at the carry-in / carry-out position H1 of the semiconductor wafer W and is placed on the support pins 70. Placed. When the loading of the semiconductor wafer W is completed, the opening 66 is closed by the gate valve 68. Further, the on-off valve 80 and the on-off valve 81 are opened to form a nitrogen gas flow in the chamber 65.

  Thereafter, the hot plate 90 rises from the carry-in / carry-out position H1 to the proximity heating position H2 by driving the motor 40, and temporarily stops there. In the first embodiment, the hot plate 90 is preheated to, for example, 400 ° C. by the action of the heater built in the heating plate 74. When the hot plate 90 is located at the proximity heating position H2, the semiconductor wafer W supported by the support pins 70 is gradually heated by the radiant heat from the hot plate 90. In the first embodiment, the hot plate 90 is stopped at the proximity heating position H2 for 30 seconds, and the proximity heating of the semiconductor wafer W is performed during this time, and the temperature of the semiconductor wafer W is gradually increased.

  Thereafter, the hot plate 90 rises from the proximity heating position H2 to the delivery position H3 by driving the motor 40, receives the semiconductor wafer W supported by the support pins 70 on the susceptor 73, and further places the semiconductor wafer W mounted thereon. The plate 90 moves up to the heat treatment position H4 and holds the semiconductor wafer W in a horizontal posture. When the hot plate 90 rises to the delivery position H3 and receives the semiconductor wafer W, the susceptor 73 and the semiconductor wafer W come into direct contact with each other, so that the temperature of the semiconductor wafer W rises rapidly. That is, in the first embodiment, the preheating treatment of the semiconductor wafer W is performed by both the proximity heating described above and the direct heating by bringing the susceptor 73 and the semiconductor wafer W into contact with each other.

  The semiconductor wafer W is continuously heated by the hot plate 90. When the temperature of the semiconductor wafer W rises, a temperature sensor (not shown) always monitors whether or not the surface temperature of the semiconductor wafer W has reached the preheating temperature of 400 ° C. Even if the semiconductor wafer W is heated to such a preheating temperature of 400 ° C., ions implanted into the semiconductor wafer W will not diffuse.

  Eventually, when the surface temperature of the semiconductor wafer W reaches the preheating temperature of 400 ° C., the flash lamp 69 is turned on to perform flash heating. The lighting time of the flash lamp 69 in this flash heating process is a time of about 0.1 to 10 milliseconds. Thus, in the flash lamp 69, the electrostatic energy stored in advance is converted into such an extremely short light pulse, so that an extremely strong flash light is irradiated.

  By such flash heating, the surface temperature of the semiconductor wafer W instantaneously reaches the temperature T. This temperature T is a temperature necessary for the ion activation treatment of the semiconductor wafer W at about 1000 ° C. to 1100 ° C. When the surface of the semiconductor wafer W is heated to such a processing temperature T, ions implanted into the semiconductor wafer W are activated.

  At this time, since the surface temperature of the semiconductor wafer W is raised to the processing temperature T in an extremely short time of about 0.1 to 10 milliseconds, ion activation in the semiconductor wafer W is completed in a short time. . Therefore, the ions implanted into the semiconductor wafer W do not diffuse, and it is possible to prevent the phenomenon that the profile of the ions implanted into the semiconductor wafer W is lost. Since the time required for ion activation is extremely short compared with the time required for ion diffusion, the ion activation is performed even for a short time in which no diffusion of about 0.1 millisecond to 10 millisecond occurs. Complete.

  Further, since the surface temperature of the semiconductor wafer W is preheated to the preheating temperature of 400 ° C. using the hot plate 90 before the flash lamp 69 is turned on to heat the semiconductor wafer W, the flash lamp 69 It becomes possible to quickly raise the temperature of the semiconductor wafer W to the processing temperature T of about 1000 ° C. to 1100 ° C.

  After the flash heating process is completed, the hot plate 90 is lowered from the heat treatment position H4 to the loading / unloading position H1 by driving the motor 40, and the opening 66 closed by the gate valve 68 is opened. Then, the semiconductor wafer W placed on the support pins 70 is carried out by a transfer robot (not shown). As described above, a series of heat treatment operations is completed.

  In the first embodiment, the hot plate 90 is stopped for 30 seconds at the proximity heating position H2 where the upper surface of the hot plate 90 and the semiconductor wafer W supported by the support pins 70 are in a non-contact proximity state, and the semiconductor wafer W is stopped. Next, the hot plate 90 is further raised and the semiconductor wafer W is directly placed on the hot plate 90. Therefore, since the semiconductor wafer W is first heated gradually after being heated by proximity heating and then rapidly heated, it is possible to prevent the semiconductor wafer W from undergoing a rapid temperature change and cause the semiconductor wafer W to warp. The semiconductor wafer W can be preheated by the hot plate 90 without any problem.

  Here, in the first embodiment, the average temperature increase rate of the semiconductor wafer W in the preheating process from when the hot plate 90 reaches the proximity heating position H2 until the surface temperature of the semiconductor wafer W reaches the preheating temperature 400 ° C. Is about 11 ° C./sec. According to the experiment of the present inventor, when the time for stopping the hot plate 90 at the proximity heating position H2 is less than 30 seconds, that is, the average heating rate of the semiconductor wafer W in the preheating step is 11 ° C./sec. It has been found that the semiconductor wafer W is warped when it is increased. For this reason, the ascending operation of the hot plate 90 is controlled so that the average temperature rising rate of the semiconductor wafer W in the preheating step is 11 ° C./sec or less. Specifically, in the first embodiment, the hot plate 90 is controlled. Is stopped at the proximity heating position H2 for 30 seconds.

  If it does in this way, the curvature of the semiconductor wafer W in a preheating process can be prevented, As a result, favorable flash heat processing can be performed.

<2. Second Embodiment>
Next, a second embodiment of the present invention will be described. The heat treatment apparatus of the second embodiment is also an apparatus for performing heat treatment of a substrate such as a semiconductor wafer by flash light from a xenon flash lamp, and since the apparatus configuration is exactly the same as that of the first embodiment, description thereof is omitted (FIG. 1). To FIG. 3). The second embodiment is different from the first embodiment in that the hot plate 90 is raised. In other words, in the second embodiment, the controller 10 controls the motor 40 to change the speed at which the hot plate 90 rises from the loading / unloading position H1 to the heat treatment position H4. FIG. 5 is a diagram illustrating a change in the rising speed of the hot plate 90 according to the second embodiment.

  Also in the heat treatment apparatus of the second embodiment, in a state where the hot plate 90 is disposed at the loading / unloading position H1 of the semiconductor wafer W, the semiconductor wafer W is loaded and supported by the transfer robot (not shown) through the opening 66. It is placed on the pin 70. When the loading of the semiconductor wafer W is completed, the opening 66 is closed by the gate valve 68. Further, the on-off valve 80 and the on-off valve 81 are opened to form a nitrogen gas flow in the chamber 65.

  Thereafter, the hot plate 90 rises from the loading / unloading position H1 to the delivery position H3 by driving the motor 40 and receives the semiconductor wafer W supported by the support pins 70 on the susceptor 73. The ascending speed of the hot plate 90 from the carry-in / carry-out position H1 to the delivery position H3 is relatively slow. Then, after receiving the semiconductor wafer W at the delivery position H3, the hot plate 90 places the semiconductor wafer W in a horizontal posture and moves up to the heat treatment position H4. The ascending speed of the hot plate 90 from the delivery position H3 to the heat treatment position H4 is relatively fast. That is, as shown in FIG. 5, the rising speed of the hot plate 90 until the semiconductor wafer W is placed on the hot plate 90 is higher than the rising speed after the semiconductor wafer W is placed on the hot plate 90. The controller 10 controls the motor 40 so as to be slower.

  While the hot plate 90 that has been heated to 400 ° C. in advance by the action of the heater built in the heating plate 74 is slowly rising from the loading / unloading position H1 to the delivery position H3, the hot plate 90 is gradually approaching. The semiconductor wafer W supported by the support pins 70 is gradually heated by the radiant heat and gradually rises in temperature. After the hot plate 90 receives the semiconductor wafer W, the susceptor 73 and the semiconductor wafer W are in direct contact with each other, so that the temperature of the semiconductor wafer W rises rapidly. That is, also in the second embodiment, the preheating process of the semiconductor wafer W is performed by both proximity heating that raises the hot plate 90 relatively slowly and direct heating by bringing the susceptor 73 and the semiconductor wafer W into contact with each other. is there.

  The heat treatment operation other than the preheating treatment is the same as that in the first embodiment. That is, when the surface temperature of the semiconductor wafer W reaches the preheating temperature of 400 ° C. by the preheating treatment, the flash lamp 69 is turned on to perform flash heating. By this flash heating, the surface temperature of the semiconductor wafer W instantaneously reaches 1000 ° C. to 1100 ° C., and ions implanted in the semiconductor wafer W are activated.

  After the flash heating process is completed, the hot plate 90 is lowered from the heat treatment position H4 to the loading / unloading position H1 by driving the motor 40, and the opening 66 closed by the gate valve 68 is released. Then, the semiconductor wafer W placed on the support pins 70 is carried out by a transfer robot (not shown). As described above, a series of heat treatment operations is completed.

  In the second embodiment, the hot plate 90 is raised relatively slowly until the semiconductor wafer W supported by the support pins 70 comes into contact with the hot plate 90, and the semiconductor wafer W and the hot plate 90 come into contact with each other. Raises the hot plate 90 to the heat treatment position H4 relatively rapidly. Accordingly, while the hot plate 90 is moving up relatively slowly, the semiconductor wafer W is gradually heated by the hot plate 90 approaching slowly, and then heated in direct contact with the hot plate 90. Therefore, it is possible to prevent the semiconductor wafer W from undergoing a rapid temperature change, and the semiconductor wafer W can be preheated by the hot plate 90 without causing the semiconductor wafer W to be warped.

  Here, also in the second embodiment, in the preheating step from the time when the hot plate 90 rising relatively slowly starts to raise the temperature of the semiconductor wafer W until the surface temperature of the semiconductor wafer W reaches the preheating temperature of 400 ° C. The average heating rate of the semiconductor wafer W is set to 11 ° C./sec or less. As described above, it has been found that when the average heating rate of the semiconductor wafer W is higher than 11 ° C./sec., The semiconductor wafer W is warped. For this reason, the average rise of the semiconductor wafer W in the preheating step is determined. The ascending operation of the hot plate 90 is controlled so that the temperature rate becomes 11 ° C./sec or less. Specifically, in the second embodiment, the rising speed of the hot plate 90 until the semiconductor wafer W is placed on the hot plate 90 is higher than the rising speed after the semiconductor wafer W is placed on the hot plate 90. Is also slow.

  If it does in this way, the curvature of the semiconductor wafer W in a preheating process can be prevented, As a result, favorable flash heat processing can be performed.

<3. Modification>
While the embodiments of the present invention have been described above, the present invention is not limited to the above examples. For example, in the above embodiment, the light source 5 is provided with 30 flash lamps 69, but the present invention is not limited to this, and the number of flash lamps 69 may be arbitrary.

  Further, the technique according to the present invention can be applied to a heat treatment apparatus that includes another type of lamp (for example, a halogen lamp) instead of the flash lamp 69 in the light source 5 and heats the semiconductor wafer W by light irradiation from the lamp. Can be applied. That is, the technique as in each of the above embodiments can be applied when performing preliminary heating to assist heating by light irradiation from the lamp.

  In addition, the present invention is not limited to an apparatus that performs heating by light irradiation, and it is needless to say that the technique according to the present invention can be applied to a heat treatment apparatus that heats a semiconductor wafer W or the like using a hot plate such as a CVD apparatus. In particular, when the temperature of the semiconductor wafer W or the like is increased by bringing the semiconductor wafer W or the like into contact with a hot plate having a high temperature of about several hundred degrees, it is significant to apply the technique according to the present invention.

  Further, from the viewpoint of surely preventing the warpage of the semiconductor wafer W by making the average temperature rising rate of the semiconductor wafer W in the preheating process smaller than 11 ° C./sec., The hot plate 90 is stopped at the proximity heating position H2. The time may be increased to 30 seconds or more, or the rising speed of the hot plate 90 to the delivery position H3 may be further slowed down. However, if the average temperature rise rate of the semiconductor wafer W in the preheating step is too small, the throughput of the heat treatment apparatus is remarkably reduced. Therefore, the average temperature rise rate is preferably 5 ° C./sec. .

  In each of the above embodiments, the hot plate 90 is moved up and down by the motor 40. However, the hot plate 90 may be fixed and the support pin 70 may be driven up and down. That is, the hot plate 90 and the support pin 70 may be moved up and down relatively.

  In addition, the ascending speed of the hot plate 90 from the loading / unloading position H1 to the delivery position H3 in the second embodiment is not necessarily limited to be constant. For example, as the hot plate 90 approaches the delivery position H3, The rising speed may be slowed down.

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

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

It is a sectional side view which shows the structure of the heat processing apparatus concerning this invention. It is a sectional side view which shows the structure of the heat processing apparatus concerning this invention. It is a block diagram which shows the structure of the controller of the heat processing apparatus of FIG. It is a figure explaining the height position which the hot plate of the heat processing apparatus of FIG. 1 can move. It is a figure explaining the change of the raising speed of the hot plate of 2nd Embodiment.

Explanation of symbols

5 Light source 10 Controller 11 CPU
40 Motor 61 Translucent plate 65 Chamber 69 Flash lamp 70 Support pin 71 Reflector 73 Susceptor 74 Heating plate 90 Hot plate H1 Loading / unloading position H2 Proximity heating position H3 Delivery position H4 Heat treatment position W Semiconductor wafer

Claims (8)

A heat treatment apparatus for heating a substrate,
A hot plate for placing and heating the substrate;
A support pin capable of supporting the substrate above the hot plate;
Relative elevating means for relatively elevating and moving the hot plate and the support pin;
Lift control means for controlling the relative lifting means to adjust the distance between the upper surface of the hot plate and the substrate supported by the support pins;
With
The elevating control means controls the relative elevating means so that an average temperature rising rate of a substrate heated by the hot plate is 11 ° C./sec or less. The heat treatment apparatus according to claim 1, wherein
The elevation control means stops the elevation movement for a predetermined time at a position where the upper surface of the hot plate and the substrate supported by the support pins are in a non-contact proximity state, and then the hot plate and the support pins are moved relative to each other. And a relative elevating means for controlling the relative elevating means so that the substrate is placed on the hot plate. The heat treatment apparatus according to claim 1, wherein
The raising / lowering control means is configured such that a relative raising / lowering moving speed of the hot plate and the support pin until the substrate is placed on the hot plate is a relative raising / lowering rate after the substrate is placed on the hot plate. A heat treatment apparatus that controls the relative lifting and lowering means so as to be slower than a moving speed. In the heat processing apparatus in any one of Claims 1-3,
A heat treatment apparatus comprising: a flash lamp for further heating the substrate by irradiating flash light onto the substrate preheated by the hot plate. A heat treatment method for heating a substrate,
A hot plate for placing and heating the substrate and a support pin for supporting the substrate above the hot plate are relatively moved up and down so that the average temperature rise rate of the substrate is 11 ° C./sec or less. The heat processing method characterized by the above-mentioned. The heat treatment method according to claim 5, wherein
The elevation movement is stopped for a predetermined time at a position where the upper surface of the hot plate and the substrate supported by the support pins are in a non-contact proximity state, and then the hot plate and the support pins are moved up and down relatively. A heat treatment method comprising placing the substrate on the hot plate. The heat treatment method according to claim 5, wherein
The relative up / down movement speed of the hot plate and the support pins until the substrate is placed on the hot plate is made slower than the relative up / down movement speed after the substrate is placed on the hot plate. The heat processing method characterized by the above-mentioned. In the heat treatment method according to any one of claims 5 to 7,
A heat treatment method comprising: further heating the substrate by irradiating flash light from a flash lamp onto the substrate preheated by the hot plate.

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