JP5264220B2 - Wafer heat treatment equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wafer heat treatment apparatus in which the temperature can be quickly raised or lowered while the temperature distribution is kept uniform with high accuracy regardless of the infrared transmissivity of a wafer. <P>SOLUTION: The wafer heat treatment apparatus 10 comprises a plurality of induction heating coils 12 (12a-12d) arranged concentrically and a plurality of annular graphite portions 14 (14a-14d) corresponding to the induction heating coils 12, respectively. The apparatus includes a wafer holding means 16 for placing the wafer 40 in a gap between the wafer 40 to be heat-treated and the graphite portions 14. The cross section of the graphite portion 14 has a semicircular shape. Preferably, the wafer heat treatment apparatus 10 having the characteristics described above comprises a reflector plate 18 that is placed opposing to the graphite portions 14 through the wafer 40 and reflects radiant rays having passed through the wafer 40. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a wafer heat treatment apparatus, and more particularly to a wafer heat treatment apparatus suitable for heat treatment of a wafer that requires rapid temperature raising / lowering treatment.

  As a means for rapidly heating a wafer when heat-treating a semiconductor wafer, a heating method is known in which an induction heating member such as graphite is induction-heated and the wafer is heated by radiant heat from the induction heating member. Yes.

  As a wafer heat treatment apparatus for carrying out such a heating method, an apparatus as disclosed in Patent Document 1 is known. The wafer heat treatment apparatus disclosed in Patent Document 1 includes an induction heating coil that forms a so-called Baumkuchen type body and a disc-shaped induction heating member that are arranged on a concentric circle. And in the wafer heat processing apparatus currently disclosed by patent document 1, the influence of the magnetic flux with respect to the graphite as a to-be-induced heating member, specifically, the magnetic flux which arises from each induction heating coil is in the heating area | region by another induction heating coil. The purpose of this is to investigate the degree of interference in advance and perform highly accurate temperature distribution control in consideration of magnetic flux interference between induction heating coils.

  However, in such a wafer heat treatment apparatus, there is a case where the temperature distribution of the wafer is biased due to the influence of heat conduction from adjacent heating zones in the graphite or the deviation of the center position between the wafer and the graphite. Moreover, since the center part of the graphite becomes a singular point of the heating region by the induction heating coil formed in the C type (Baumkuchen type), there is a problem that the heating rate is slow. Further, in the wafer heat treatment apparatus having such a configuration, when heating a wafer having a high infrared transmittance, it is necessary to set the heating temperature of the graphite higher than the conventional one. In this case, in the temperature lowering process, the temperature drop of the graphite is slow, so that there is a problem that the rapid temperature lowering process is difficult.

For such a wafer heat treatment device, graphite is divided into a plurality of annular shapes so as not to be affected by heat conduction from adjacent heating regions, and even with a large diameter wafer, the temperature distribution is uniform. A wafer heat treatment apparatus intended to perform heat treatment while maintaining high accuracy is disclosed in Patent Document 2.
Japanese Patent Laid-Open No. 2004-241302 Japanese Patent Laid-Open No. 2005-11868

  In the case of the wafer heat treatment apparatus disclosed in the above-mentioned Patent Document 2, it is considered that each of the annular graphites is not affected by heat conduction from the adjacent heating region. However, since the wafer heating apparatus disclosed in Patent Document 2 has a wafer mounted directly on graphite, there is a difference in both heat transfer and radiation heating between a place where the graphite is present and a place where the graphite is not present. May occur.

  Therefore, in the present invention, a wafer heat treatment apparatus that solves the above-described problems and can perform a rapid temperature raising / lowering process regardless of the infrared transmittance while maintaining a uniform temperature distribution of the wafer with high accuracy. The purpose is to provide.

In order to achieve the above object, a wafer heat treatment apparatus according to the present invention comprises a plurality of induction heating coils arranged concentrically and a plurality of annular induction heating members associated with the induction heating coils. a wafer heat-treatment apparatus having the wafer holding comprises means, each of the plurality of the object to be induction heating member section for placing the wafer by providing a gap between the target induction heating member and the wafer to be heat treated subject The upper surface of the shape is convex.

  In the wafer heat treatment apparatus having the above-described features, it is preferable that the wafer heat treatment apparatus includes a reflection plate that is disposed to face the induction heating member through the wafer and reflects the radiation transmitted through the wafer. With such a configuration, the heating efficiency of the wafer can be improved.

  In order to achieve the above object, a wafer heat treatment apparatus according to the present invention comprises a plurality of induction heating coils arranged concentrically and a plurality of annular induction heating members associated with the induction heating coils. And a wafer holding means for placing the wafer with a gap between the wafer to be heat-treated and the induction heating member, and the induction heating via the wafer. It may be provided with a reflection plate disposed opposite to the member and reflecting the radiation transmitted through the wafer.

  In each wafer heat treatment apparatus having the above-described features, it is desirable that cooling means be disposed between the plurality of annular induction heating members. With such a configuration, the cooling rate in the temperature lowering process can be increased.

  Further, the wafer heat treatment apparatus having the above-described features includes a separator that separates the coil chamber having the induction heating coil from the process chamber in which the wafer is disposed, and a thick portion is formed in a part of the separator. The thin portion may be reinforced. By adopting such a configuration, the gas pressure in the coil chamber can be set to atmospheric pressure regardless of the gas pressure in the process chamber, and a cooling gas or the like can be introduced inside to improve the cooling efficiency. become able to.

  According to the wafer heat treatment apparatus having the above-described features, it is possible to perform the rapid temperature raising / lowering process regardless of the infrared transmittance while keeping the wafer temperature distribution uniform with high accuracy.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a wafer heat treatment apparatus according to the present invention will be described in detail with reference to the drawings.
First, a first embodiment of the wafer heat treatment apparatus of the present invention will be described with reference to FIG. The wafer heat treatment apparatus 10 according to this embodiment includes at least an induction heating coil 12 (12a, 12b, 12c, 12d), graphite 14 (14a, 14b, 14c, 14d) as an induction heating member, and wafer holding means 16. With. The wafer heat treatment apparatus 10 according to the present embodiment includes a reflection plate 18 for reflecting the radiation transmitted through the wafer 40. In addition, although the induction heating coil 12 and the graphite 14 are each four in FIG. 1, increase / decrease in a number does not become a problem in implementing this invention.

  The induction heating coil 12 is a circular (C-type) coil. When viewed as a whole, a plurality of circular coils having different radii are arranged on a concentric circle, and thus form a so-called Baumkuchen-like body. A power control unit 20 is connected to the plurality of induction heating coils 12 arranged.

  The power control unit 20 is configured based on, for example, a three-phase AC power source 22, a converter 24, a chopper 26 (26a, 26b, 26c, 26d), and an inverter 28 (28a, 28b, 28c, 28d).

The converter 24 is a pure conversion unit that converts the three-phase alternating current input from the three-phase alternating current power supply 22 into direct current and outputs the direct current to the chopper 26 connected to the subsequent stage.
The chopper 26 is a voltage adjusting unit that changes the current conduction rate output from the converter 24 and changes the voltage of the current input to the inverter 28.

  The inverter 28 is an inverse conversion unit that converts the direct current adjusted in voltage by the chopper 26 into an alternating current and supplies the alternating current to the induction heating coil 12. Note that the inverter 28 of the induction heating apparatus exemplified in this embodiment is a series resonance type inverter in which the induction heating coil 14 and the resonance capacitors 30 (30a, 30b, 30c, 30d) are arranged in series. Further, an inverter 28 and a chopper 26 are individually connected to the plurality of (four in the present embodiment) induction heating coils 12. In addition, control of the output current from the inverter 28 to the induction heating coil 12 shall be performed based on the input signal from the drive control part which is not shown in figure.

  According to the power control unit 20 as described above, the voltage of the current output from the converter 24 can be controlled by the chopper 26, and the direct current output from the chopper 26 can be converted and the frequency adjusted by the inverter 28. Therefore, the output power can be controlled by the chopper 26, and the inverter 28 can adjust the phase with the frequency of the current supplied to the induction heating coil 12 in which a plurality of coils are arranged adjacent to each other. Then, the phase of the frequency in the output current is synchronized (the phase difference is set to 0 or approximated to 0) or is maintained at a predetermined interval, so that mutual induction between the adjacent induction heating coils 12 is performed. The influence can be avoided, and the temperature of the object to be heated can be controlled by controlling the input power to the induction heating coil 12.

  Moreover, the induction heating coil 12 according to the present embodiment has a hollow structure as shown in FIG. 1 and is formed so that a refrigerant (for example, water) can be inserted therein. By adopting such a configuration, it is possible to prevent the induction heating coil 12 itself from being overheated by receiving radiation or heat transfer from the graphite 14 serving as a heat source.

  The graphite 14 is formed in a ring shape as a heating zone corresponding to each induction heating coil 12. As shown in FIG. 2, the graphite 14 is configured to arrange a plurality of rings on concentric circles. As shown in FIG. 2, by providing a gap between adjacent graphites 14, variations in temperature distribution control due to heat transfer between adjacent graphites 14 can be avoided. Further, since the heat capacity is smaller than that of flat (disc-shaped) graphite, it becomes possible to increase the reactivity of heating and cooling in heating and cooling. Furthermore, since the heating zone by each induction heating coil 12 is clearly defined, it is possible to suppress the deviation of the temperature distribution of the wafer 40 due to the deviation of the heating region.

  In the graphite 14 according to the present embodiment, the cross-sectional shape in the radial direction, that is, the cross-sectional shape of the ring is a bowl-shaped (cylindrical) convex shape as shown in FIG. With such a configuration, the upper side (upper surface) in the cross section of the graphite 12 becomes a curved surface that is convex upward, so that the radiation angle of radiation emitted from the upper surface can be widened. For this reason, even when the distance between the wafer 40 to be heat-treated and the graphite 14 is relatively close, the intermittent portion of the graphite 14 can be compensated for as an infrared reachable range as radiation. Then, the heating efficiency of the wafer 40 can be improved by reducing the distance between the wafer 40 and the graphite 14. In FIG. 1, the cross-sectional shape of the graphite is a saddle shape, but if it is an upwardly convex chevron shape, a triangular shape as shown in FIG. 3 is a polygonal shape as shown in FIG. 4. May be. This is because even in such a form, the infrared radiation range for the wafer 40 can be expanded.

  The wafer holding means 16 is a component for holding the wafer 40. The wafer holding means 16 is provided at a position where the wafer 40 to be heat-treated can be held with a gap between the wafer 40 and the graphite 14. The configuration may be an edge ring that holds the outer edge portion of the wafer 40 or a claw that supports several points on the outer edge portion of the wafer 40. The gap (distance) between the wafer 40 and the graphite 14 may be a distance at which the entire main surface of the wafer 40 is irradiated with infrared rays from the graphite 14, and an infrared radiation angle or circle emitted from the graphite 14 is sufficient. It varies depending on the gap of the annular graphite 14. As an example, it may be about 2 to 3 cm.

  The reflector 18 plays a role of reflecting infrared rays transmitted through the wafer 40 out of infrared rays emitted from the graphite 14 and contributing to heating of the wafer 40 again. Therefore, the reflector 18 is disposed so as to oppose the graphite 14 through the wafer 40. Although the reflecting plate 18 shown in FIG. 1 is flat, the opposing surface may be a concave curved surface.

  According to the wafer heat treatment apparatus 10 as described above, even when the heating temperature of the graphite 14 is improved when heating the wafer 40 having a high infrared transmittance, the heat capacity of the individual graphite 14 is small, Since the end portion of the graphite 14 is present, the emissivity is high, so that the temperature drop rate can be improved. Therefore, the reactivity at the time of performing a rapid temperature raising / lowering process can be improved. Further, since the cross-sectional shape of the graphite 14 is a mountain shape, the infrared irradiation range can be widened, and even when the distance between the graphite 14 and the wafer 40 is reduced, the wafer 40 can be heated evenly. It becomes feasible. Further, the graphite 14 is formed in an annular shape, and the distance from the wafer 40 is appropriately determined, thereby eliminating the problem of a low temperature phenomenon at the central portion which is a singular point. Therefore, regardless of the infrared transmittance of the wafer 40, it is possible to perform the rapid temperature raising / lowering process while maintaining a uniform temperature distribution with high accuracy.

  In addition, when the arrangement interval of the induction heating coils 12 is determined in accordance with the arrangement interval of the graphite 14, the mutual inductance between the induction heating coils 12 arranged adjacent to each other is reduced, and the design and manufacture of the wafer heat treatment apparatus 10 is performed. Becomes easy.

  In the above description, the wafer heat treatment apparatus 10 according to the embodiment is described as being used for a low temperature process of about 500 ° C. or lower, but the wafer heat treatment apparatus according to the present embodiment is a high temperature process exceeding 1000 ° C. Can respond.

Next, an embodiment related to the wafer heat treatment apparatus of the present invention will be described with reference to FIG. Most of the configuration of the wafer heat treatment apparatus according to this embodiment is the same as that of the wafer heat treatment apparatus 10 according to the first embodiment described above. Accordingly, parts having the same function are denoted by reference numerals added with 100 and detailed description thereof will be omitted.

  The difference between the wafer heat treatment apparatus 10 according to the first embodiment and the wafer heat treatment apparatus 110 according to the present embodiment is the configuration of graphite 114 (114a, 114b, 114c, 114d) as an induction heating member. Specifically, the cross-sectional shape of the graphite 14 of the wafer heat treatment apparatus 10 according to the first embodiment is a convex bowl shape, whereas the cross-sectional shape of the graphite 114 is used in the wafer heat treatment apparatus 110 according to this embodiment. Is a rectangle.

  When the cross-sectional shape of the graphite 114 is rectangular, the radiation angle of the radiation radiated from the upper surface of the graphite 114 becomes narrow. Therefore, in order to perform uniform heating of the wafer 140, the wafer 140 is compared with the first embodiment. Although it is necessary to increase the distance between the graphite 114 and the graphite 114, a similar effect can be obtained.

  In addition, in the wafer heat treatment apparatuses 10 and 110 according to the first and second embodiments, cooling means are disposed between each of the annularly formed annular graphites in order to improve the reactivity during temperature reduction. be able to. Specifically, as shown in FIG. 6, a C-shaped cooling pipe 234 (234a, 234b, 234c, 234d, 234e) having a hollow structure is connected to graphite 214 (214a, 214b, 214c, 214d, 214e). They are arranged in the gaps (the gaps of graphite 14 in the first embodiment and the gaps of graphite 114 in the second embodiment), respectively, and the refrigerant is inserted into the cooling pipe 234. With such a configuration, the cooling pipe 234 absorbs the heat of the graphite 212, and the cooling effect of the graphite 212 can be enhanced. When the temperature of the graphite 234 becomes lower than that of the wafers 40 and 140, the graphite 214 loses its function as a heat source and acts as a heat absorption source that absorbs the heat of the wafers 40 and 140. Therefore, in the heat treatment of the wafers 40 and 140, the reactivity of the temperature lowering process can be improved. When the wafers 40 and 140 are heated, the refrigerant may be inserted through the cooling pipe 234 or stopped. This is because the heating of the wafers 40 and 140 is possible if the heat generation energy of the graphite 214 is larger than the heat absorption action by the refrigerant.

  Here, it is desirable that the cooling pipe 234 is made of an insulator. However, as shown in FIG. 6, if the cooling pipe 234 has an open type (C type), There is no risk of generating heat due to induction heating. 6A is a diagram showing a partial cross section of graphite, and FIG. 6B is a diagram showing a planar configuration of graphite.

  Further, it is not always necessary to provide one induction heating coil for the planar shape of the graphite, and as shown in FIG. 7, two induction heating coils (for example, induction heating coils 12a and 12b) are used. On the other hand, one graphite 314a may be provided.

  Then, as shown in FIG. 7, a coil chamber 60 in which the induction heating coil 12 and the graphite 314 are disposed, and a process chamber (in which the outer shell side boundary line is not illustrated) 62 in which the wafer 40 is disposed are separated by a separator such as quartz. It may be separated by 50. This is because such a configuration suppresses the possibility of contamination (contamination) on the coil chamber 60 side from entering the process chamber 62 side.

  In the wafer heat treatment apparatus having such a configuration, the gas pressure on the process chamber 62 side may be set lower than the atmospheric pressure to perform the heat treatment. In this case, in order to prevent the warp of the separator 50 due to the pressure difference between the process chamber 62 and the coil chamber 60 and the crack of the separator 50 due to the warp, the thickness of the separator 50 is increased, or the coil chamber 60 side It is necessary to take measures to reduce the gas pressure.

  However, in this case, if the thickness of the separator 50 is increased, the distance between the wafer 40 and the graphite 314 or the distance between the induction heating coil 12 and the graphite 314 is increased (between the induction heating coil 12 and the graphite 314). In the case where the separator 50 is disposed on the wafer 40), the heating efficiency of the wafer 40 is reduced. Further, when the pressure on the coil chamber 60 side is lowered, the minimum voltage at which Paschen discharge occurs is lowered, so that the cooling gas for cooling the graphite 314 and the like cannot be used in the coil chamber 60, and the cooling rate in the temperature lowering process becomes slow. Etc. arise.

  Therefore, in the present invention, when the separator as described above is provided, as shown in FIG. 7, a thick portion 50b is provided in a part of the separator 50 to reinforce the thin portion 50a. In this case, the thick part 50b corresponding to the reinforcing part is preferably formed or arranged so as to be positioned in a gap between the plurality of graphites 314 divided into an annular shape. This is because the provision of the thick portion 50b at such a position hardly affects the heating of the graphite 314 and the heating of the wafer 40 by radiation.

It is a figure which shows the structure of the wafer heat processing apparatus which concerns on 1st Embodiment. It is a figure which shows the planar form of the graphite which concerns on invention. It is a figure which shows the modification of the cross-sectional shape of the graphite in the wafer heat processing apparatus which concerns on 1st Embodiment. It is a figure which shows the other modification of the cross-sectional shape of the graphite in the wafer heat processing apparatus which concerns on 1st Embodiment. It is a figure which shows the structure of the wafer heat processing apparatus which concerns on embodiment relevant to this invention . It is a figure which shows the applied form of the graphite which concerns on invention. It is a figure which shows the application form of the wafer heat processing apparatus which concerns on invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ......... Wafer heat treatment apparatus, 12 (12a, 12b, 12c, 12d) ......... Induction heating coil, 14 (14a, 14b, 14c, 14d) ......... Graphite, 16 ......... Wafer holding means, 18 ... …… Reflector 20 …… Power control unit 22 …… Three-phase AC power source 24 …… Converter 26 (26a, 26b, 26c, 26d) ……… Chopper 28 (28a, 28b, 28c) 28d) ... inverter, 30 (30a, 30b, 30c, 30d) ... series capacitor, 40 ... wafer.

Claims (3)

A wafer heat treatment apparatus having a plurality of induction heating coils arranged on concentric circles and a plurality of annular induction heating members associated with each induction heating coil,
A wafer holding means for placing the wafer with a gap between the wafer to be heat-treated and the induction heating member;
The upper surface in the cross-sectional shape of each of the plurality of induction heating members is a convex shape ,
A wafer heat treatment apparatus , wherein a cooling means is disposed between each of the plurality of annular induction heating members .   2. The wafer heat treatment apparatus according to claim 1, further comprising a reflection plate that is disposed to face the induction heating member through the wafer and reflects radiation rays transmitted through the wafer. 3. It has a separator that separates the coil chamber having the induction heating coil from the process chamber in which the wafer is arranged, and a thick part is formed in a part of the separator, and the thin part is reinforced. The wafer heat treatment apparatus according to claim 1 or 2 .

Images