JP2005032949A - Apparatus and method for heat treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide such a technology that can apply flash irradiation in a state where the temperature gradient of substrate surface is relieved, in a heat treatment apparatus and a heat treatment method by which an air current is formed around the substrate and assist heating and flash irradiation are applied to the substrate. <P>SOLUTION: In a heating period between a time t0 and t6 of assist heating, the flow rate V1 per a unit time of an air current that is formed around the substrate between a time t2 a specified time before a time t3 of starting flash irradiation and a time t5 or later after a time t4 when the flash irradiation is completed, is made smaller than a flow rate V2 per a unit time of the air current around before and after the time. Thus, the cooling effect of the air current to the substrate between the time t2 and the time t5 can be reduced, and the flash irradiation can be applied in a state where the temperature gradient of the substrate surface is relieved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat treatment apparatus and a heat treatment method for performing flash irradiation while performing assist heating on a substrate in a state where an airflow is formed around a semiconductor wafer, a glass substrate or the like (hereinafter simply referred to as “substrate”). .
[0002]
[Prior art]
Conventionally, in an ion activation process of a semiconductor wafer after ion implantation, a heat treatment apparatus such as a lamp annealing apparatus using a halogen lamp has been used. In such a heat treatment apparatus, the semiconductor wafer is ion-activated by heating (annealing) the semiconductor wafer to a temperature of about 1000 ° C. to 1100 ° C., for example. In such a heat treatment apparatus, the temperature of the substrate is raised at a rate of several hundred degrees per second by using the energy of light irradiated from the halogen lamp.
[0003]
However, even when ion activation of a semiconductor wafer is performed using a heat treatment apparatus that raises the temperature of the substrate at a speed of several hundred degrees per second, the profile of ions implanted into the semiconductor wafer is reduced, that is, due to heat It has been found that a phenomenon occurs in which ions diffuse. 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.
[0004]
In order to solve the above-mentioned problems, flash irradiation is performed on the surface of the semiconductor wafer using a xenon flash lamp or the like, so that only the surface of the semiconductor wafer into which ions are implanted is raised in a very short time (several milliseconds or less). Techniques for heating have been proposed (see, for example, Patent Documents 1 and 2). If the temperature is raised for a very short time by flash irradiation, there is not enough time for ions to diffuse, so only ion activation is performed without squinting the profile of ions implanted in the semiconductor wafer. It can be done.
[0005]
By the way, in the heat treatment in which the temperature of the semiconductor wafer is increased by performing flash irradiation in this way, the semiconductor wafer is assisted heated to a temperature (200 ° C. to 600 ° C.) at which implanted ions are not diffused. In some cases, flash irradiation may be performed thereon (see, for example, Patent Document 3). This is because it is difficult to raise the temperature of the surface of the semiconductor wafer to the temperature necessary for ion activation (about 1000 ° C. to 1100 ° C.) only with the energy of the flash light irradiated from the xenon flash lamp.
[0006]
In addition, in the heat treatment in which the temperature of the semiconductor wafer is increased by performing flash irradiation, there are cases where such assist heating or flash irradiation is performed in a state where an inert gas stream is formed around the semiconductor wafer (for example, And Patent Document 3). This is mainly to reduce the oxygen concentration in the atmosphere around the semiconductor wafer while receiving assist heating or flash irradiation.
[0007]
[Patent Document 1]
JP 59-169125 A
[Patent Document 2]
JP 63-166219 A
[Patent Document 3]
JP 2003-173983 A
[0008]
[Problems to be solved by the invention]
However, in such heat treatment, when assist heating is performed in a state where an airflow is formed around the semiconductor wafer, the surface of the semiconductor wafer is cooled by the airflow, and a temperature gradient is generated on the surface of the semiconductor wafer. Specifically, the portion located on the upstream side of the air flow on the surface of the semiconductor wafer is more strongly cooled than the portion located on the downstream side, and therefore tends to be relatively low in temperature.
[0009]
When the semiconductor wafer having a temperature gradient on the surface is irradiated with flash light in this way, the temperature reached by the semiconductor wafer due to flash irradiation becomes non-uniform, and the activation of the ions is activated in the semiconductor wafer. It becomes difficult to execute uniformly throughout.
[0010]
The present invention has been made in view of such problems, and in the heat treatment apparatus or heat treatment method for performing assist heating and flash irradiation on the substrate while forming an air flow around the substrate, the temperature of the substrate surface is provided. An object of the present invention is to provide a technique capable of performing flash irradiation in a state where the gradient is relaxed.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is a heat treatment apparatus for processing a substrate, and assist heating means for performing assist heating on the substrate within a predetermined heating period, and the substrate during the assist heating. A flash irradiation unit that performs flash irradiation on the substrate, an air flow forming unit that forms an air flow around the substrate during the heating period, a flow rate adjusting unit that adjusts a flow rate of the air flow, and the flash irradiation of the heating period. The flow rate per unit time of the airflow from the predetermined time before the start time to the time when the flash irradiation ends or until the predetermined time thereafter is lower than the flow rate per unit time of the airflow before and after the time And a control means for controlling the flow rate adjusting means.
[0012]
A second aspect of the present invention is the heat treatment apparatus according to the first aspect, wherein the control means performs a time when the flash irradiation ends or a predetermined time after the predetermined time before the time when the flash irradiation starts. The flow rate adjusting means is controlled so as to stop the airflow during the period up to.
[0013]
The invention according to claim 3 is the heat treatment apparatus according to claim 1 or 2, wherein the predetermined time is not less than 0.1 seconds and not more than 10 seconds.
[0014]
According to a fourth aspect of the present invention, there is provided a heat treatment method for treating a substrate, wherein an assist heating step for performing assist heating on the substrate within a predetermined heating period, and performing flash irradiation on the substrate during assist heating. A flash irradiation step, and an air flow formation step of forming an air flow around the substrate during the heating period, wherein the flash irradiation ends from a predetermined time before the start of the flash irradiation. The flow rate per unit time of the airflow between the time to be performed or a predetermined time thereafter is set lower than the flow rate per unit time of the airflow before and after the time.
[0015]
The invention according to claim 5 is the heat treatment method according to claim 4, wherein, in the airflow formation step, a time at which the flash irradiation ends or a time after a predetermined time before the time at which the flash irradiation starts. The airflow until a predetermined time is stopped.
[0016]
The invention according to claim 6 is the heat treatment method according to claim 4 or 5, wherein the predetermined time is not less than 0.1 seconds and not more than 10 seconds.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0018]
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.
[0019]
This heat treatment apparatus includes a light transmitting plate 61, a bottom plate 62, and a pair of side plates 63 and 64, and includes a chamber 65 for housing the semiconductor wafer W and heat-treating it. 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. is doing. The bottom plate 62 constituting the chamber 65 is provided with support pins 70 that pass through a heat diffusion plate 73 and a heating plate 74 described later to support the semiconductor wafer W from its lower surface.
[0020]
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 released. When the heat treatment of the semiconductor wafer W is performed in the chamber 65, the opening 66 is closed by the gate valve 68, and the atmosphere inside the chamber 65 is shut off from the outside atmosphere.
[0021]
Above the chamber 65, a light source 5 serving as flash irradiation means is provided. The light source 5 includes a plurality (27 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 a plane parallel to 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.
[0022]
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.
[0023]
A light diffusing plate (diffuser) 72 is disposed between the light source 5 and the translucent plate 61. The light diffusing plate 72 uses a surface of quartz glass as an infrared transmitting material that has been subjected to a light diffusing process, and diffuses light emitted from each of the plurality of flash lamps 69.
[0024]
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.
[0025]
In the chamber 65, a heating plate 74 and a heat diffusion plate 73 are provided as assist heating means. The heat diffusion plate 73 is attached to the upper surface of the heating plate 74.
[0026]
The heating plate 74 is for assisting heating (preliminary heating) of the semiconductor wafer W. The heating plate 74 is made of aluminum nitride and has a structure in which a heater and a sensor for controlling the heater are housed. On the other hand, the heat diffusing plate 73 is for diffusing the heat energy from the heating plate 74 to uniformly assist and heat the semiconductor wafer W, and has a slightly larger system than the semiconductor wafer W in plan view. As a material of the heat diffusion plate 73, sapphire (Al ₂ O ₃ : Aluminum oxide) or quartz having a relatively low thermal conductivity is employed.
[0027]
The heat diffusing plate 73 and the heating plate 74 are 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. .
[0028]
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 heat diffusion plate 73 and the heating plate 74 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. it can.
[0029]
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). This is the position where the heat diffusion plate 73 and the heating plate 74 are lowered so that the completed semiconductor wafer W can be carried out from the opening 66. In this state, the upper end of the support pin 70 passes through the through holes formed in the heat diffusion plate 73 and the heating plate 74 and protrudes upward from the surface of the heat diffusion plate 73.
[0030]
On the other hand, the heat treatment position of the semiconductor wafer W shown in FIG. 2 is a position where the heat diffusion plate 73 and the heating plate 74 are raised above the upper ends of the support pins 70 in order to perform heat treatment on the semiconductor wafer W. In the process in which the heat diffusion plate 73 and the heating plate 74 are raised from the loading / unloading position of FIG. 1 to the heat treatment position of FIG. 2, the semiconductor wafer W placed on the support pins 70 is received by the heat diffusion plate 73 and its lower surface. Is supported by the surface of the heat diffusing plate 73, and is held in a horizontal posture at a position in the chamber 65 close to the translucent plate 61. Conversely, in the process in which the heat diffusion plate 73 and the heating plate 74 are lowered from the heat treatment position to the carry-in / carry-out position, the semiconductor wafer W supported by the heat diffusion plate 73 is transferred to the support pins 70.
[0031]
In a state where the thermal diffusion plate 73 and the heating plate 74 that support the semiconductor wafer W are raised to the heat treatment position, the translucent plate 61 is located between the semiconductor wafer W held by them and the light source 5. Note that the distance between the heat diffusion plate 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.
[0032]
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 heat diffusing plate 73 and the heating plate 74 are raised to the heat treatment position, the bellows 77 contracts, and when the heat diffusion plate 73 and the heating plate 74 are lowered to the loading / unloading position, the bellows 77 is expanded to form the atmosphere in the chamber 65. Shut off from outside atmosphere.
[0033]
An introduction path 78 for introducing an inert gas such as nitrogen gas or argon gas into the chamber 65 is formed in the side plate 63 opposite to the opening 66 in the chamber 65. FIG. 7 is a horizontal sectional view of a member including the introduction path 78. The introduction path 78 has a plurality of discharge holes 781 in the chamber 65, and can introduce an inert gas into the chamber 65 (in the direction of the arrow in FIG. 7). Further, the other end side of the introduction path 78 is connected to an inert gas supply source 82 through a flow rate control valve 80. Note that the flow rate control valve 80 used here is a valve that can be switched between open and closed, and can arbitrarily throttle the flow rate of the inert gas that passes through when it is opened, that is, the flow rate of the inert gas that passes through the flow rate adjustment valve is 0. It is assumed that the valve can be adjusted within the above range. In addition, the expression “adjusting the flow rate” in this specification is an expression used in the meaning including “stopping the flow”. By operating the flow rate adjusting valve 80, the inert gas can be introduced into the chamber 65 from the inert gas supply source 82, and the flow rate of the inert gas to be introduced can be adjusted.
[0034]
On the other hand, a discharge path 79 for discharging the gas in the chamber 65 is formed in the opening 66 in the side plate 64. The discharge path 79 is connected to an exhaust means (not shown) through an on-off valve 81. For this reason, the inert gas introduced from the initial atmosphere in the chamber 65 or the introduction path 78 can be exhausted by opening the on-off valve 81, and the exhaust can be stopped by closing the on-off valve 81. it can.
[0035]
FIG. 3 is an enlarged side sectional view of the periphery of the semiconductor wafer W held on the heat diffusion plate 73. By opening both the flow control valve 80 and the on-off valve 81 as described above, an inert gas stream G is formed around the semiconductor wafer W from the introduction path 78 side to the discharge path 79 side. In the present embodiment, the oxygen concentration around the semiconductor wafer W is lowered in this way. Further, by operating the flow rate adjusting valve 80, the flow rate per unit time of the air flow G can be adjusted. At this time, the flow rate control valve 80, the on-off valve 81, and the inert gas supply source 82 function as air flow forming means for forming an inert gas flow G around the semiconductor wafer W. It also functions as a flow rate adjusting means for adjusting the flow rate of the air flow G.
[0036]
The control means 10 is electrically connected to the flow rate adjusting valve 80 and the on-off valve 81. The control means 10 can operate opening and closing of each valve by transmitting predetermined electric signals to the flow rate adjusting valve 80 and the opening and closing valve 81, respectively.
[0037]
Next, the heat treatment operation of the semiconductor wafer W by the heat treatment apparatus having the above configuration will be described. A semiconductor wafer W to be processed in this heat treatment apparatus is a semiconductor wafer after ion implantation.
[0038]
FIG. 4A is a graph showing an outline of a change in the surface temperature of the semiconductor wafer W during a heating period (between time t1 and time t6) during which assist heating or flash irradiation is performed in the present embodiment. . However, there are times when the surface temperature of the semiconductor wafer W is not uniform between the time t1 and the time t6, but in the graph of FIG. 4A, the average surface temperature of the upper surface of the semiconductor wafer W at each time. Is shown. FIG. 4B is a graph showing a change in the flow rate per unit time of the airflow G formed around the semiconductor wafer W in the same manner from time t1 to time t6. Hereinafter, in addition to FIGS. 1 to 3, FIG. 4A and FIG. 4B will be described as needed.
[0039]
In this heat treatment apparatus, in a state in which the thermal diffusion plate 73 and the heating plate 74 are arranged at the loading / unloading positions of the semiconductor wafer W shown in FIG. It is carried in and placed on the support pin 70. When the loading of the semiconductor wafer W is completed, the opening 66 is closed by the gate valve 68. Thereafter, the heat diffusion plate 73 and the heating plate 74 are raised to the heat treatment position of the semiconductor wafer W shown in FIG. 2 by driving the motor 40 to hold the semiconductor wafer W in a horizontal posture.
[0040]
At this time, the heat diffusing plate 73 and the heating plate 74 are preheated to a predetermined temperature by the action of a heater built in the heating plate 74. Therefore, a heating period including continuous assist heating is started from time t0 when the heat diffusing plate 73 holds the semiconductor wafer W and the semiconductor wafer W comes into contact with the heat diffusing plate 73, as shown in FIG. As described above, the temperature of the semiconductor wafer W gradually increases.
[0041]
Further, at least at time t0 when the semiconductor wafer W is held on the upper surface of the thermal diffusion plate 73, the flow control valve 80 and the on-off valve 81 are automatically opened by the control means 10, and an inert gas flow in the chamber 65 is obtained. Is formed. Therefore, as shown in FIG. 3B, an airflow G having a predetermined flow rate V2 is also formed around the semiconductor wafer W.
[0042]
When the temperature of the semiconductor wafer W rises, it is always monitored whether or not the surface temperature of the semiconductor wafer W has reached the assist heating temperature T1 by a temperature sensor (not shown). The assist heating temperature T1 is, for example, a temperature of about 200 ° C. to 600 ° C., preferably about 350 ° C. to 550 ° C. Even if the semiconductor wafer W is heated to such an assist heating temperature T1, ions implanted into the semiconductor wafer W will not diffuse.
[0043]
The flow rate control valve 80 is controlled at a time t2 after a time t3 after the time t1 when the surface temperature of the semiconductor wafer W reaches the assist heating temperature T1 and before the flash irradiation from the flash lamp 69 is started. The flow rate per unit time of the air flow G of the inert gas that is automatically adjusted by the means 10 and formed around the semiconductor wafer W decreases from the flow rate V2 to the flow rate V1. Between the time t1 and the time t2, an air flow G having a relatively high flow rate V2 is formed around the semiconductor wafer W receiving the assist heating. Therefore, a temperature gradient is generated on the surface of the semiconductor wafer W due to the cooling effect of the airflow G at the flow rate V2. However, after the inert gas stream is reduced to the flow rate V1 at time t2, the cooling effect is also reduced, so that the temperature gradient on the surface of the semiconductor wafer W is relaxed.
[0044]
Here, the time from the time t2 to the time t3 (t3-t2) needs to be a time that can obtain an effect of relaxing the temperature gradient on the surface of the semiconductor wafer W. Specifically, the time gradient (t3-t2) can obtain a temperature gradient relaxation effect in 0.1 seconds or more, and if it is about 10 seconds, heat conduction in the thermal diffusion plate 73 is sufficiently performed and the temperature gradient. Can be relaxed. On the other hand, the time (t3-t2) is preferably as short as possible in order not to increase the oxygen concentration in the ambient atmosphere of the semiconductor wafer W. Therefore, it is desirable to set the time (t3−t2) between 0.1 seconds and 10 seconds.
[0045]
After relaxing the temperature gradient on the surface of the semiconductor wafer W in this way, the flash lamp 69 is turned on at time t3 to start flash irradiation. This flash irradiation continues for an extremely short time of about 0.1 to 10 milliseconds, and ends at time t4. In the flash irradiation by 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.
[0046]
By such flash irradiation, the surface temperature of the semiconductor wafer W instantaneously reaches the temperature T2. This temperature T2 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 T2, ions implanted into the semiconductor wafer W are activated.
[0047]
At this time, since the surface temperature of the semiconductor wafer W is raised to the processing temperature T2 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.
[0048]
Further, before the semiconductor wafer W is heated by turning on the flash lamp 69, the surface temperature of the semiconductor wafer W is heated to the assist heating temperature T1 of about 200 ° C. to 600 ° C. using the heating plate 74. The flash lamp 69 makes it possible to quickly raise the temperature of the semiconductor wafer W to the processing temperature T2 of about 1000 ° C. to 1100 ° C.
[0049]
Then, at time t5 after time t4 when the flash irradiation by the flash lamp 69 ends, the flow rate adjusting valve 80 is automatically adjusted by the control means 10, and the flow rate per unit time of the airflow G formed around the semiconductor wafer W is changed. The flow rate V1 is increased again from the flow rate V1. The interior of the chamber 65 is designed to be cut off from the external atmosphere, and if the flow rate of the air flow G is reduced for a short time, the oxygen concentration in the ambient atmosphere of the semiconductor wafer W should not rise to a problem level. If the flow rate decrease of the airflow G is continued for a long time, the oxygen concentration in the ambient atmosphere of the semiconductor wafer W may gradually increase. The reason why the flow rate per unit time of the airflow G is increased again is to suppress such an increase in oxygen concentration.
[0050]
Thereafter, the heat diffusion plate 73 and the heating plate 74 are lowered to the loading / unloading position of the semiconductor wafer W shown in FIG. At time t6 when the heat diffusing plate 73 and the heating plate 74 are descending, the semiconductor wafer W held on the heat diffusing plate 73 is transferred again onto the support pins 70, and the assist heating is finished.
[0051]
Further, the opening 66 closed by the gate valve 68 is released, and the semiconductor wafer W placed on the support pins 70 is unloaded by a transfer robot (not shown), and a series of heat treatment operations is completed.
[0052]
Thus, in the heat treatment according to the present embodiment, in the heating period from time t0 to time t6, time t5 after time t4 when flash irradiation ends from time t2 a predetermined time before time t3 when flash irradiation starts. Until then, the flow rate V1 per unit time of the airflow G formed around the semiconductor wafer W is made lower than the flow rate V2 per unit time of the airflow G before and after that. For this reason, the cooling effect of the airflow G with respect to the semiconductor wafer W between the time t2 and the time t5 can be reduced. Therefore, from time t3 to time t4, flash irradiation can be performed with the temperature gradient on the surface of the semiconductor wafer W relaxed.
[0053]
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the above-mentioned example.
[0054]
For example, in the above-described embodiment, the case where the flow rate per unit time of the airflow formed around the semiconductor wafer W is reduced from the time t2 to the time t5 has been described. However, if the flow rate V1 to be reduced is low, the flow rate is low. Thus, the effect of relaxing the temperature gradient can be better obtained. Therefore, as shown in FIG. 5, it is more preferable that the airflow G formed around the semiconductor wafer W is stopped between the time t2 and the time t5.
[0055]
Further, when the air flow G from time t2 to time t5 is stopped, the on / off valve 81 is used as the flow rate adjusting means instead of the flow rate adjusting valve 80, and the flow rate of the air flow G is adjusted by opening / closing the on / off valve 81. Form may be sufficient.
[0056]
In the above-described embodiment, the case where the gas formed around the semiconductor wafer W is adjusted in two stages of the flow rate V2 and the flow rate V1 has been described. It is not limited. For example, the flow rate per unit time of the airflow G before the time t2 and the flow rate per unit time of the airflow G after the time t5 may be different. That is, if the flow rate is adjusted so that the flow rate per unit time of the air flow G during the heating period from t2 to t5 is relatively lower than the flow rate per unit time of the air flow G before and after that, the present invention. The effect of can be obtained.
[0057]
In the above-described embodiment, the mode in which the flow rate per unit time of the airflow G is increased again at the time t5 has been described. However, in order to more reliably suppress the increase in the oxygen concentration, the time t5 is preferably after the time t4. It is desirable to set the time earlier. Therefore, as shown in FIG. 6, it is more preferable if the flow rate per unit time of the airflow G is increased again at the same time as the end of the flash irradiation by the flash lamp 69 at time t4.
[0058]
In the above-described embodiment, the case where the assist heating is performed by the energy supplied from the heating plate 74 has been described. However, the assist heating is performed by the energy of light continuously irradiated from a lamp such as a halogen lamp. May be.
[0059]
Moreover, although the gas which comprises the airflow G demonstrated in the above-mentioned embodiment the case where it was an inert gas aiming at reducing oxygen concentration, the other gas which has another objective may be sufficient. . That is, the present invention can be applied when an air flow is formed around the semiconductor wafer W to be heat-treated with some necessity.
[0060]
In the above-described embodiment, the case where the substrate to be processed is the semiconductor wafer W has been described. However, the present invention can be applied to a glass substrate and other tangible substrates in general.
[0061]
【The invention's effect】
As described above, according to the first to sixth aspects of the present invention, the periphery of the substrate between a predetermined time before the time when the flash irradiation starts and a time when the flash irradiation ends or after the predetermined time thereafter. Since the cooling effect of the substrate due to the airflow formed on the substrate can be reduced, flash irradiation can be performed with the temperature gradient of the substrate surface relaxed.
[0062]
In particular, according to the invention described in claim 2 or claim 4, the effect of relaxing the temperature gradient on the substrate surface can be obtained more favorably.
[0063]
In particular, according to the invention described in claim 3 or claim 6, it is possible to obtain an effect of relaxing the temperature gradient on the substrate surface without increasing the oxygen concentration in the ambient atmosphere of the substrate.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing a configuration of a heat treatment apparatus according to the present invention.
FIG. 2 is a side sectional view showing a configuration of a heat treatment apparatus according to the present invention.
3 is an enlarged side sectional view of the periphery of a semiconductor wafer W held on a heat diffusion plate 73. FIG.
4 is a graph showing an outline of a change in the surface temperature of the semiconductor wafer W and a change in the flow rate per unit time of the airflow G during the heating period. FIG.
FIG. 5 is a graph showing a change in the flow rate per unit time of the air flow G in a mode in which the air flow G formed around the semiconductor wafer W is stopped between the time t2 and the time t5.
FIG. 6 is a graph showing a change in the flow rate per unit time of the airflow G in the form in which the flow rate per unit time of the airflow G is increased again simultaneously with the end of flash irradiation by the flash lamp 69;
7 is a horizontal sectional view of a member including an introduction path 78. FIG.
[Explanation of symbols]
5 Light source
10 Control means
65 chambers
69 Xenon flash lamp
70 Support pin
73 Heat diffusion plate
74 Heating plate
78 Introduction
79 Discharge path
80 Flow control valve
81 On-off valve
82 Inert gas source
G Airflow
T1 assist heating temperature
T2 processing temperature
V1, V2 flow rate
W Semiconductor wafer
t0 to t6 time

Claims (6)

A heat treatment apparatus for processing a substrate,
Assist heating means for performing assist heating on the substrate within a predetermined heating period;
Flash irradiation means for performing flash irradiation on the substrate during the assist heating,
Airflow forming means for forming an airflow around the substrate in the heating period;
Flow rate adjusting means for adjusting the flow rate of the air flow;
In the heating period, the flow rate per unit time of the air flow from a predetermined time before the time when the flash irradiation starts to the time when the flash irradiation ends or until a predetermined time thereafter is the air flow before and after the air flow. Control means for controlling the flow rate adjusting means so as to be lower than the flow rate per unit time,
A heat treatment apparatus comprising: The heat treatment apparatus according to claim 1,
The control means controls the flow rate adjusting means so as to stop the airflow from a predetermined time before the time when the flash irradiation starts to a time when the flash irradiation ends or until a predetermined time thereafter. A heat treatment apparatus characterized by The heat treatment apparatus according to claim 1 or 2,
The heat treatment apparatus characterized in that the predetermined time is not less than 0.1 seconds and not more than 10 seconds. A heat treatment method for treating a substrate,
An assist heating step of performing assist heating on the substrate within a predetermined heating period;
A flash irradiation step of performing flash irradiation on the substrate during the assist heating;
An airflow forming step of forming an airflow around the substrate in the heating period;
With
In the airflow forming step, the flow rate per unit time of the airflow from the predetermined time before the time when the flash irradiation is started to the time when the flash irradiation is ended or until the predetermined time thereafter, The heat processing method characterized by making it lower than the flow volume per unit time of airflow. The heat treatment method according to claim 4,
In the airflow forming step, the airflow is stopped from a predetermined time before the time when the flash irradiation is started to a time when the flash irradiation is ended or until a predetermined time thereafter. The heat treatment method according to claim 4 or 5,
The heat treatment method, wherein the predetermined time is 0.1 second or more and 10 seconds or less.

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