JP4272445B2 - Heat treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
This invention relates to a heat treatment apparatus having a heat treatment for a susceptor that holds a substrate to be the processing target when the substrate is heat-treated such as a semiconductor wafer.
[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, 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 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 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.
[0005]
In addition, the heat treatment is not limited to the heating method by light irradiation. Generally, in a heat treatment apparatus, heat treatment is often performed in a state where a substrate is held by a susceptor having excellent heat resistance (see, for example, Patent Documents 3 and 4).
[0006]
[Patent Document 1]
JP 59-169125 A [Patent Document 2]
JP-A 63-166219 [Patent Document 3]
JP-A-10-74705 [Patent Document 4]
Japanese Unexamined Patent Publication No. 2000-355766
[Problems to be solved by the invention]
By the way, since the xenon flash lamp instantaneously irradiates the semiconductor wafer with light having extremely high energy, the surface temperature of the semiconductor wafer rapidly rises instantaneously, and when the energy of the irradiating light exceeds a certain threshold value, the surface rapidly changes. Due to the thermal expansion of the semiconductor wafer, the semiconductor wafer is cracked with high probability. For this reason, when the heat treatment is actually performed, light of energy having a certain margin (process margin) less than the above threshold is irradiated.
[0008]
However, when the wafer is heated by flash irradiation from a xenon flash lamp in a state where the semiconductor wafer is held on the susceptor, the semiconductor wafer may be broken even if flash light having an energy less than the above threshold is irradiated. This is because when the wafer surface suddenly thermally expands due to flash exposure and the semiconductor wafer tries to warp convexly, if the wafer edge is in contact with the pocket edge of the susceptor or positioning pins, This is because there is no time for the wafer to slide on the susceptor to relieve such stress while a large force is applied to the substrate. As a result, even when a flash of energy less than the above threshold is irradiated, if the edge of the semiconductor wafer is in contact with something, the wafer will be cracked by the stress received from it during instantaneous thermal expansion. It was.
[0009]
The present invention has been made in view of the above problems, and an object thereof is to provide a heat treatment apparatus that can be prevented cracking of the substrate during heat treatment.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems, a first aspect of the present invention is a heat treatment apparatus for heating a substrate by irradiating the substrate with flash light, and is provided with a light source having a plurality of flash lamps and a lower portion of the light source. A chamber having an upper chamber window through which flash light emitted from the light source is transmitted, and holding means for holding the substrate in a substantially horizontal position in the chamber, wherein the holding means includes: A flat placement surface having a region equal to or larger than a plane size; a first taper surface surrounding the periphery of the placement surface to define the placement surface; and surrounding the periphery of the first taper surface And a lower end portion of the first tapered surface is connected to the peripheral edge portion of the mounting surface, and a lower end portion of the second tapered surface is connected to an upper end portion of the first tapered surface. As before The first tapered surface is formed to be wider upward, the second opening defined by the upper end of the tapered surface is wider than the placement surface, the slope of the first tapered surface with respect to the mounting surface is less than 5 ° above 30 °, chromatic and large heat-treating the susceptor than the gradient is the first tapered surface of the second tapered surface with respect to said mounting face, and the assist heating means for preheating the substrate to hold the is doing.
[0011]
According to a second aspect of the present invention, in the heat treatment apparatus according to the first aspect of the present invention, the surface average roughness of the first tapered surface is 1.6 μm or less .
[0012]
According to a third aspect of the present invention, in the heat treatment apparatus according to the first or second aspect of the present invention, the gradient of the second tapered surface with respect to the placement surface is 45 ° or more and 90 ° or less .
[0013]
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 gradient of the first tapered surface with respect to the mounting surface is 10 ° or more and less than 20 ° .
[0014]
According to a fifth aspect of the present invention, in the heat treatment apparatus according to any one of the first to fourth aspects of the present invention, the material of the heat treatment susceptor is quartz .
[0015]
According to a sixth aspect of the present invention, in the heat treatment apparatus according to any one of the first to fifth aspects, the length of the first tapered surface along the direction parallel to the mounting surface is 0.1 mm. It is set to 5.0 mm or less .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0017]
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 circular semiconductor wafer by flash light from a xenon flash lamp.
[0018]
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 susceptor 73 and a heating plate 74 described later and support the semiconductor wafer W from the lower surface thereof.
[0019]
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.
[0020]
The chamber 65 is provided below the light source 5. 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 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.
[0021]
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.
[0022]
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.
[0023]
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.
[0024]
A heating plate 74 and a susceptor 73 are provided in the chamber 65. The susceptor 73 is attached to the upper surface of the heating plate 74. The heating plate 74 and the susceptor 73 constitute holding means for holding the semiconductor wafer W in the chamber 65 in a substantially horizontal posture.
[0025]
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. Details of the susceptor 73 will be described later.
[0026]
The susceptor 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.
[0027]
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. For this reason, the susceptor 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.
[0028]
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 susceptor 73 and the heating plate 74 are lowered so that the semiconductor wafer W can be carried out from the opening 66. In this state, the upper end of the support pin 70 passes through a through hole formed in the susceptor 73 and the heating plate 74 and protrudes upward from the surface of the susceptor 73.
[0029]
On the other hand, the heat treatment position of the semiconductor wafer W shown in FIG. 2 is a position where the susceptor 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 susceptor 73 and the heating plate 74 are 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 rises while being supported by the surface, and is held in a horizontal position at a position close to the translucent plate 61 in the chamber 65. Conversely, in the process in which the susceptor 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 susceptor 73 is transferred to the support pins 70.
[0030]
In a state where the susceptor 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 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.
[0031]
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 susceptor 73 and the heating plate 74 are raised to the heat treatment position, the bellows 77 contracts, and when the susceptor 73 and the heating plate 74 are lowered to the loading / unloading position, the bellows 77 is extended, and the atmosphere in the chamber 65 and the external atmosphere are increased. Cut off.
[0032]
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.
[0033]
Further description of the susceptor 73 will be continued. 3 and 4 are a side sectional view and a plan view of the susceptor 73, respectively. The susceptor 73 of this embodiment is configured by forming a concave portion 97 having a circular shape when viewed from above on a disk-shaped member. The recess 97 functions to position and hold the semiconductor wafer W on the susceptor 73.
[0034]
The mounting surface 99 of the susceptor 73 is the bottom surface of the recess 97. The mounting surface 99 is a circular plane having a diameter slightly larger than the diameter of the semiconductor wafer W, that is, a flat surface having a region equal to or larger than the plane size of the semiconductor wafer W. A first tapered surface 95 is formed so as to surround the peripheral portion of the mounting surface 99 which is the bottom surface of the recess 97. The lower end portion 95a of the first taper surface 95 is connected to the peripheral edge portion of the placement surface 99, and the placement surface 99 is defined by the first taper surface 95 if viewed differently. The mounting surface 99 only needs to be a plane when viewed from the whole susceptor 73, and is a surface provided with fine irregularities of about several tens of micrometers in order to improve the temperature distribution uniformity of the semiconductor wafer W during heat treatment. May be.
[0035]
A second taper surface 93 is formed so as to surround the peripheral portion of the first taper surface 95. That is, the peripheral edge portion of the recess 97 is a two-step inclined surface, the lower step is the first taper surface 95, and the upper step is the second taper surface 93. The lower end portion 93 a of the second tapered surface 93 is connected to the upper end portion 95 b of the first tapered surface 95. The circular opening defined by the upper end portion 95 b of the first taper surface 95 is parallel to the placement surface 99, and the diameter thereof is larger than the diameter of the placement surface 99. That is, the tapered surface 95 is formed so as to widen upward.
[0036]
On the other hand, the upper end portion 93 b of the second tapered surface 93 is connected to the peripheral surface 91 of the susceptor 73. The peripheral surface 91 is an annular plane and is parallel to the placement surface 99. The inner diameter of the peripheral surface 91 is larger than the diameter of the mounting surface 99. That is, the circular opening defined by the upper end portion 93 b of the second tapered surface 93 is wider than the placement surface 99.
[0037]
The gradient α of the first tapered surface 95, which is the lower stage of the two-step inclined surface for forming the concave portion 97, with respect to the mounting surface 99 may be 5 ° or more and less than 30 °, and is set to 15 ° in this embodiment. (See FIG. 5). Further, the surface average roughness (Ra) of the first taper surface 95 may be 1.6 μm or less, and Ra = 1.6 μm in this embodiment. Furthermore, the gradient β of the second tapered surface 93, which is the upper stage of the two-step inclined surface for forming the concave portion 97, with respect to the mounting surface 99 may be larger than the gradient α of the first tapered surface 95, and preferably 45 ° or more. It is 90 ° or less, and in this embodiment, it is 75 °.
[0038]
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.
[0039]
In this heat treatment apparatus, the semiconductor wafer W is loaded through the opening 66 by a transfer robot (not shown) in a state where the susceptor 73 and the heating plate 74 are arranged at the loading / unloading position of the semiconductor wafer W shown in FIG. , 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 susceptor 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, and the semiconductor wafer W is held in a horizontal posture. Further, the on-off valve 80 and the on-off valve 81 are opened to form a nitrogen gas flow in the chamber 65.
[0040]
Here, in the process in which the susceptor 73 and the heating plate 74 are raised, the susceptor 73 receives the semiconductor wafer W placed on the support pins 70. At this time, a thin air layer is sandwiched between the susceptor 73 and the semiconductor wafer W for several seconds after the semiconductor wafer W is transferred from the support pins 70 to the susceptor 73, and the semiconductor wafer W is removed from the susceptor 73 by the air layer. Slightly floated. In such a state, the phenomenon that the semiconductor wafer W moves so as to slide in the recess 97 due to some cause (for example, a slight inclination) and the wafer end is rebounded by the first taper surface 95 is repeated for several seconds. .
[0041]
Thereafter, the air layer is eventually removed, so that the semiconductor wafer W is stably held in the recess 97 of the susceptor 73. That is, the slightly floating semiconductor wafer W is positioned by the first tapered surface 95 and is held on the lowermost position of the recess 97, that is, on the mounting surface 99 without providing a special positioning pin or the like. It is. The diameter of the mounting surface 99 is slightly larger than the diameter of the semiconductor wafer W, and the semiconductor wafer W is normally positioned and held eccentrically on the mounting surface 99, so that one point at the peripheral end is the first taper. It will be stably held in contact with the surface 95. Further, when the semiconductor wafer W moves so as to slide in the recess 97, the wafer end may run on the first taper surface 95 depending on the moving speed. Since the second tapered surface 93 is steeper than the surface 95, the semiconductor wafer W is prevented from jumping out of the susceptor 73.
[0042]
The susceptor 73 and the heating plate 74 are preheated to a predetermined temperature by the action of a heater built in the heating plate 74. For this reason, in a state where the susceptor 73 and the heating plate 74 are raised to the heat treatment position of the semiconductor wafer W, the semiconductor wafer W is preliminarily heated by coming into contact with the heated susceptor 73, and the temperature of the semiconductor wafer W gradually increases. To do.
[0043]
In this state, the semiconductor wafer W is continuously heated by the susceptor 73. 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 T1.
[0044]
The preheating temperature T1 is, for example, about 200 ° C. to 600 ° C. Even if the semiconductor wafer W is heated to such a preheating temperature T1, ions implanted into the semiconductor wafer W will not diffuse.
[0045]
Eventually, when the surface temperature of the semiconductor wafer W reaches the preheating temperature T1, 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.
[0046]
By such flash heating, 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 flash lamp 69 is turned on to heat the semiconductor wafer W, the surface temperature of the semiconductor wafer W is heated to the preheating 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]
After the flash heating process is completed, the susceptor 73 and the heating plate 74 are lowered to the loading / unloading position of the semiconductor wafer W shown in FIG. 1 by driving the motor 40 and the opening 66 closed by the gate valve 68 is opened. Is done. As the susceptor 73 and the heating plate 74 are lowered, the semiconductor wafer W is transferred from the susceptor 73 to the support pins 70. 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.
[0050]
In the process in which the susceptor 73 and the heating plate 74 are lowered, the semiconductor wafer W held by the susceptor 73 is transferred to the support pins 70. At this time, since the gradient of the first taper surface 95 with respect to the mounting surface 99 is relatively gentle, the support pins 70 in a state where the semiconductor wafer W after the heat treatment rides on the first taper surface 95 and is displaced. May be passed to When the degree of positional deviation of the semiconductor wafer W is large, there arises a problem that the transfer robot cannot properly receive the semiconductor wafer W from the support pins 70. Here, in the present embodiment, since the second tapered surface 93 that is steeper than the first tapered surface 95 is present outside the first tapered surface 95, when the semiconductor wafer W held by the susceptor 73 is transferred to the support pins 70, As a result, the semiconductor wafer W is prevented from being displaced greatly. That is, the second taper surface 93 prevents the semiconductor wafer W from jumping out when the wafer is transferred between the susceptor 73 and the support pins 70.
[0051]
By the way, when the semiconductor wafer W is heated by turning on the flash lamp 69, the surface of the wafer is suddenly thermally expanded by the flash irradiation, and the semiconductor wafer W tends to warp in a convex shape. At this time, if the end portion of the semiconductor wafer W is in contact with the positioning pins or the like, the semiconductor wafer W may be cracked by the stress received from it during instantaneous thermal expansion, as described above. .
[0052]
In the present embodiment, the gradient α of the first tapered surface 95 with respect to the placement surface 99 is 15 °. As described above, the semiconductor wafer W is normally stably held in a state where one point of the peripheral end portion is in contact with the first tapered surface 95. Here, if the slope α of the first taper surface 95 is less than 30 °, as shown in FIG. 5, even when the semiconductor wafer W is instantaneously thermally expanded, as indicated by the arrow AR5 in the figure, The end of the semiconductor wafer W (the end in contact with the tapered surface 95) can slide with respect to the first tapered surface 95. That is, by setting the gradient α of the first taper surface 95 to less than 30 °, the end portion of the semiconductor wafer W is not restrained by the first taper surface 95, so that the semiconductor wafer W is turned on when the flash lamp 69 is turned on. It can expand freely. As a result, even if the wafer surface rapidly expands due to a flash exposure, the semiconductor wafer W will not receive a large stress from the first tapered surface 95, and the semiconductor wafer W can be prevented from cracking during the flash exposure. it can.
[0053]
In order for the end portion of the semiconductor wafer W to slide with respect to the first tapered surface 95 during such instantaneous thermal expansion, the gradient α of the first tapered surface 95 with respect to the mounting surface 99 is set to be less than 30 °. There must be. When the gradient α of the first taper surface 95 is 30 ° or more, the static frictional force between the end portion of the semiconductor wafer W and the first taper surface 95 increases, and the end portion (first step) of the semiconductor wafer W during instantaneous thermal expansion. This is because the end portion in contact with the first taper surface 95 cannot slide, and as a result, the semiconductor wafer W may break due to the restraining stress from the first taper surface 95. If the gradient α of the first taper surface 95 is less than 30 °, the end portion of the semiconductor wafer W can slide with respect to the first taper surface 95. In particular, if the gradient α is less than 20 °, the end of the semiconductor wafer W The frictional force between the first taper surface 95 and the first taper surface 95 becomes extremely small, and the stress that the semiconductor wafer W receives from the first taper surface 95 becomes very small even if the wafer surface is rapidly expanded due to flash irradiation. Further, it is possible to more reliably prevent the semiconductor wafer W from being cracked during the flash irradiation.
[0054]
On the other hand, when the gradient α of the first taper surface 95 with respect to the mounting surface 99 is less than 5 °, the positioning effect of the semiconductor wafer W by the first taper surface 95 as described above can hardly be obtained, and the susceptor 73 can be connected to the semiconductor wafer W. When the semiconductor wafer W is received, the semiconductor wafer W may collide with the second tapered surface 93 violently. For this reason, the gradient α of the first tapered surface 95 with respect to the mounting surface 99 needs to be 5 ° or more, and in order to obtain a particularly stable positioning effect of the semiconductor wafer W, the gradient α should be 10 ° or more. preferable.
[0055]
Further, in order to reduce the frictional force between the end portion of the semiconductor wafer W and the first tapered surface 95 so that the end portion can freely slide, the surface property of the first tapered surface 95 is also important. . That is, when the coefficient of friction between the end portion of the semiconductor wafer W and the first tapered surface 95 is small, the end portion is easily slipped with respect to the first tapered surface 95. For this reason, it is preferable that the surface average roughness (Ra) of the first taper surface 95 is 1.6 μm or less. If it is within this range, the frictional force between the end of the semiconductor wafer W and the first taper surface 95 is preferred. Since the stress applied to the semiconductor wafer W from the first taper surface 95 is smaller even if the wafer surface undergoes rapid thermal expansion due to flash irradiation, the semiconductor wafer W is more reliably prevented from cracking during flash irradiation. can do. For this reason, in this embodiment, Ra = 1.6 μm.
[0056]
In summary, the first tapered surface 95 of the susceptor 73 according to the present invention is provided with two functions of positioning the semiconductor wafer W and preventing cracking of the semiconductor wafer W during flash irradiation. And in order to make these two functions compatible, gradient (alpha) of the 1st taper surface 95 with respect to the mounting surface 99 shall be 5 degrees or more and less than 30 degrees. If the gradient α is 5 ° or more, the semiconductor wafer W can be positioned on the mounting surface 99 by the first tapered surface 95 when the susceptor 73 receives the semiconductor wafer W, and if it is less than 30 °, it is irradiated by flash light irradiation. Excessive stress on the semiconductor wafer W is suppressed even when the wafer surface undergoes rapid thermal expansion. In order to obtain these two functions more effectively, it is preferable that the gradient α of the first tapered surface 95 with respect to the mounting surface 99 is 10 ° or more and less than 20 °. Further, if the surface average roughness (Ra) of the first taper surface 95 is 1.6 μm or less, the frictional force between the end of the semiconductor wafer W and the first taper surface 95 becomes smaller, and the wafer is irradiated by flash irradiation. Even when the surface suddenly undergoes thermal expansion, it is possible to more reliably suppress an excessive stress from being applied to the semiconductor wafer W.
[0057]
Further, as described above, the second tapered surface 93 of the susceptor 73 according to the present invention is provided with a function of preventing the semiconductor wafer W from jumping out during wafer delivery. That is, since the gradient α of the first tapered surface 95 with respect to the mounting surface 99 is relatively gentle, the semiconductor wafer W jumps out when the semiconductor wafer W is passed from the susceptor 73 to the support pins 70 only with the first tapered surface 95. The second tapered surface 93 is formed in order to prevent this from occurring. In order to prevent the semiconductor wafer W from jumping out, it is necessary to make the gradient β of the second tapered surface 93 with respect to the mounting surface 99 at least larger than the gradient α of the first tapered surface 95 with respect to the mounting surface 99. The slope β of the second tapered surface 93 is preferably 45 ° or more and 90 ° or less. Within this range, even when the semiconductor wafer W rides on the first taper surface 95 for some reason, it is impossible to ride up to the second taper surface 93, and the semiconductor wafer W from the susceptor 73 cannot be run. Popping out can be reliably prevented. For this reason, in this embodiment, the gradient β of the second tapered surface 93 with respect to the placement surface 99 is set to 75 °.
[0058]
In order to effectively obtain the effect of the two-step inclined surface as described above, the front end of the peripheral edge of the semiconductor wafer W becomes the second tapered surface 93 when the semiconductor wafer W is stably held by the susceptor 73. It is required to form a two-step inclined surface so that the transfer robot can be received within the range that can be received from the support pins 70 even if the position of the semiconductor wafer W is displaced during wafer transfer. In order to satisfy such a requirement, the length d of the first tapered surface 95 along the direction parallel to the placement surface 99 needs to be 0.1 mm or more and 5.0 mm or less. When the length d is less than 0.1 mm, the tip portion of the wafer in contact with the first taper surface 95 when the semiconductor wafer W is stably held by the susceptor 73 is the second taper surface 93. There is also a possibility that the semiconductor wafer W may be broken by the restraining stress from the moment of thermal expansion. On the other hand, if the length d is larger than 5.0 mm, the degree of positional deviation of the semiconductor wafer W at the time of wafer transfer becomes excessive, and the transfer robot may not be able to receive from the support pins 70. For this reason, the length d of the first taper surface 95 along the direction parallel to the mounting surface 99 needs to be 0.1 mm or more and 5.0 mm or less, and in this way, the semiconductor wafer W is prevented from cracking. Thus, the effect of the two-step inclined surface for preventing popping out can be obtained effectively.
[0059]
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 27 flash lamps 69, but the present invention is not limited to this, and the number of flash lamps 69 may be arbitrary.
[0060]
In the above embodiment, the support pins 70 are fixed and the susceptor 73 and the heating plate 74 are moved up and down to transfer the semiconductor wafer W between them. However, the susceptor 73 and the heating plate 74 are transferred between them. , And the support pins 70 may be moved up and down to deliver the semiconductor wafer W between them. That is, any configuration may be used as long as the susceptor 73 and the heating plate 74 and the support pin 70 are moved up and down relatively.
[0061]
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.
[0062]
【The invention's effect】
As described above, according to the first aspect of the present invention, the first tapered surface of the heat treatment susceptor is formed so as to widen upward, and the opening defined by the upper end portion of the second tapered surface is placed. The slope of the first tapered surface with respect to the mounting surface is larger than 5 ° and less than 30 °, and the gradient of the second tapered surface with respect to the mounting surface is larger than that of the first tapered surface. It is possible to prevent the substrate from cracking during the heat treatment by suppressing the excessive stress from acting on the substrate even when the thermal expansion suddenly occurs, and also to prevent the substrate from jumping out from the susceptor for heat treatment. . In addition, the substrate can be appropriately positioned on the placement surface.
[0064]
According to the invention of claim 2 , since the surface average roughness of the first taper surface is 1.6 μm or less, the frictional force between the substrate and the taper surface becomes smaller, and the substrate surface is sharpened during the heat treatment. Even when the substrate is thermally expanded, it is possible to more reliably suppress an excessive stress from acting on the substrate.
[0065]
According to the invention of claim 3 , since the gradient of the second tapered surface with respect to the mounting surface is not less than 45 ° and not more than 90 °, even if the substrate rides on the first tapered surface, the second tapered surface is used for heat treatment. It is possible to reliably prevent the substrate from jumping out of the susceptor.
[0066]
According to the invention of claim 4 , since the gradient of the first taper surface with respect to the mounting surface is 10 ° or more and less than 20 °, it is possible to more reliably prevent the substrate from being positioned and cracking during the heat treatment. it can.
[0067]
According to the invention of claim 6 , since the length of the first taper surface along the direction parallel to the mounting surface is 0.1 mm or more and 5.0 mm or less, it is possible to prevent the substrate from being cracked and prevented from popping out. it is possible to ensure things.
[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.
FIG. 3 is a side sectional view of a susceptor of the heat treatment apparatus of FIG.
4 is a plan view of a susceptor of the heat treatment apparatus of FIG. 1. FIG.
FIG. 5 is a diagram showing the behavior of a semiconductor wafer during flash irradiation.
[Explanation of symbols]
5 light source 40 motor 65 chamber 69 flash lamp 70 support pin 71 reflector 73 susceptor 74 heating plate 91 peripheral surface 93 second taper surface 95 first taper surface 99 mounting surface W semiconductor wafer α, β gradient

Claims (6)

A heat treatment apparatus for heating a substrate by irradiating the substrate with flash light,
A light source having a plurality of flash lamps;
A chamber provided below the light source and provided with a chamber window at the top for transmitting flash light emitted from the light source;
Holding means for holding the substrate in a substantially horizontal posture in the chamber;
With
The holding means is
A flat mounting surface having a region equal to or larger than a plane size of the substrate; a first tapered surface surrounding the peripheral portion of the mounting surface to define the mounting surface; and a peripheral portion of the first tapered surface And a lower end portion of the first tapered surface is connected to the peripheral portion of the mounting surface, and a lower end portion of the second tapered surface is an upper end of the first tapered surface. The first taper surface is widened upward, and the opening defined by the upper end of the second taper surface is wider than the mounting surface. The first tapered surface has a slope of 5 ° or more and less than 30 °, and the second tapered surface has a slope larger than that of the first tapered surface with respect to the placement surface;
Assist heating means for preheating the substrate to be held;
The heat processing apparatus characterized by having. The heat treatment apparatus according to claim 1, wherein
The heat treatment apparatus characterized in that the first taper surface has a surface average roughness of 1.6 μm or less . In the heat treatment apparatus according to claim 1 or 2,
The gradient of the said 2nd taper surface with respect to the said mounting surface is 45 degrees or more and 90 degrees or less, The heat processing apparatus characterized by the above-mentioned. In the heat processing apparatus in any one of Claims 1-3,
The gradient of the said 1st taper surface with respect to the said mounting surface is 10 degrees or more and less than 20 degrees, The heat processing apparatus characterized by the above-mentioned. In the heat processing apparatus in any one of Claims 1-4 ,
A heat treatment apparatus characterized in that a material of the heat treatment susceptor is quartz . In the heat processing apparatus in any one of Claims 1-5,
The length of the said 1st taper surface along the direction parallel to the said mounting surface is 0.1 mm or more and 5.0 mm or less, The heat processing apparatus characterized by the above-mentioned .

Images