JP2004356624A - Mounting stand structure and heat treatment equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting stand structure which can not only restrain surely the occurrence of contamination, such as metal smearing, but correspond to a heat treatment at a high temperature. <P>SOLUTION: The mounting stand structure has a mounting stand 32 in which a workpiece W is mounted for performing a predetermined heat treatment to the workpiece W within a treatment vessel 4, and a strut 30 which makes the mounting stand rise from the bottom of the treatment vessel and supports the mounting stand, wherein the mounting stand and the strut are formed with silica glass, respectively, and a heating means 38 is embedded in the mounting stand. Thereby, a thermal diffusion of metal atoms and the like, which causes smearing, from the mounting stand is prevented. Consequently, the occurrence of various kinds of contamination, such as metal smearing, can be prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat treatment apparatus and a mounting table structure for an object to be processed such as a semiconductor wafer.

In general, in order to manufacture a semiconductor integrated circuit, an object to be processed such as a semiconductor wafer is repeatedly subjected to various single-wafer processes such as a film forming process, an etching process, a heat treatment, a reforming process, and a crystallization process to obtain a desired object. An integrated circuit is formed. When performing various kinds of processing as described above, a processing gas required in accordance with the type of the processing, for example, a film forming gas in the case of a film forming process, an ozone gas or the like in the case of a reforming process, In the case of the crystallization treatment, an inert gas such as N ₂ gas or an O ₂ gas is introduced into the processing vessel.
For example, in the case of a single-wafer heat treatment apparatus for performing heat treatment on a semiconductor wafer one by one, for example, a mounting table having a built-in resistance heating heater is installed in a vacuum-treated processing container. A predetermined processing gas is flowed while the semiconductor wafer is mounted on the upper surface, and various heat treatments are performed on the wafer under predetermined processing conditions.

By the way, the above-mentioned mounting table is generally installed in a processing container with its surface exposed. For this reason, a slight heavy metal or the like contained in the material constituting the mounting table, for example, a ceramic or metal material such as AlN, diffuses into the processing container due to heat, and causes contamination such as metal contamination. I was Regarding contamination such as metal contamination, particularly when an organometallic material is used as a raw material gas for film formation as in recent years, particularly strict pollution control is desired.
In addition, the heater usually provided on the mounting table is divided into a plurality of zones, for example, concentrically, and the temperature is controlled individually and independently for each of these zones to realize an optimal temperature distribution for wafer processing. However, in this case, when the input power is significantly different for each zone, the difference in thermal expansion between the zones of the material constituting the mounting table may be significantly different, and the mounting table itself may be damaged. is there. In the case of a high temperature of a material such as AlN, the insulation resistance of the AlN material is significantly reduced, and a leakage current flows. For these reasons, the process temperature could not be raised above 650 ° C.

  In addition, when performing a film forming process for depositing a thin film on the wafer surface as a heat treatment, the thin film adheres as an unnecessary film not only on the target wafer surface but also on the surface of the mounting table or the inner wall surface of the processing container. Inevitable. In this case, if the unnecessary film is peeled off, particles which cause a reduction in the yield of the product are generated. Therefore, the unnecessary film is removed by flowing an etching gas into the processing container regularly or irregularly. Alternatively, a cleaning process is performed in which a structure in a processing container is immersed in an etching solution such as nitric acid to remove an unnecessary film.

  In this case, for the purpose of reducing the number of times of the above-described contamination countermeasures and cleaning processing, for example, the heating element heater is covered with a quartz casing to constitute a mounting table as disclosed in Patent Document 1, or as described in Patent Document 2. A resistance heating element is provided in a sealed quartz case as disclosed and the whole is used as a mounting table, or the heater itself is made of a quartz plate as disclosed in Patent Documents 3 and 4. It has been practiced to use it as a mounting table by sandwiching it.

JP-A-63-278322 JP-A-07-078766 JP-A-03-220718 JP-A-06-260430

  By the way, in each of the above-mentioned prior arts, since the mounting table is covered with a quartz cover or the like, it is possible to suppress the generation of contamination such as metal contamination to some extent, but the countermeasures have not been sufficient yet. Further, when the quartz plate to be used is transparent, the temperature distribution of the heater wire may be projected on the wafer temperature, and the temperature distribution in the wafer surface may be non-uniform. Further, an unnecessary thin film may adhere to the back surface of the mounting table or a cover covering the back surface in a mottled or irregular shape. In this case, the emissivity of heat is different between the thick and thin portions of the unnecessary film that has adhered, which causes a distribution in the surface temperature of the mounting table, and consequently, the non-uniformity of the temperature within the wafer surface. This causes a reduction in the in-plane uniformity of the heat treatment on the wafer.

Unnecessary films adhering to the surface of the mounting table and the surface of the cover are easily peeled off relatively quickly. Therefore, it is necessary to perform a cleaning process before the film comes off. Maintenance work had to be performed frequently. Furthermore, when the mounting table, which is a heating element, can be heated for each zone, if the power difference applied to each zone is large, there is a problem that the mounting table is damaged due to thermal expansion of the heater material. .
The present invention has been devised in view of the above problems and effectively solving the problems. An object of the present invention is not only to reliably suppress the occurrence of contamination such as metal contamination, but also to cope with high-temperature heat treatment with good heat conduction and to adjust a wide range of zones in order to obtain uniform heat. It is an object of the present invention to provide a mounting table structure and a heat treatment apparatus capable of performing the above.

Another object of the present invention is to provide a mounting table capable of maintaining high uniformity of the in-plane temperature of the mounting table by eliminating an adverse thermal effect even when an unnecessary film adheres to the mounting table in a mottled manner. It is to provide a structure and a heat treatment apparatus.
Still another object of the present invention is to provide a mounting table structure capable of preventing an unnecessary film from adhering to a mounting table or the like as much as possible, thereby making it possible to extend a maintenance cycle such as a cleaning process. And a heat treatment apparatus.
Another object of the present invention is to maintain a high uniformity of the in-plane temperature or to perform special heating by allowing the input power difference between the zones to be freely specified in a mounting table including a plurality of heating zones. It is an object of the present invention to provide a mounting table structure.

The invention according to claim 1 is to raise the mounting table on which the processing object is mounted in order to perform a predetermined heat treatment on the processing object in the processing container, and to raise the mounting table from the bottom of the processing container. A supporting table structure having a supporting column for supporting the supporting table, wherein the mounting table and the supporting column are each formed of quartz glass, and a heating unit is embedded in the mounting table. .
According to this, it is possible to prevent metal atoms and the like causing contamination from being thermally diffused from the mounting table, and thus it is possible to prevent various kinds of contamination such as metal contamination from occurring.

In this case, for example, as defined in claim 2, the column is formed in a cylindrical shape, and a power supply line for the heating means is drawn out from the center of the mounting table and the inside of the cylindrical column is directed downward. It is configured to be inserted through.
Further, for example, as set forth in claim 3, the mounting table is formed by joining an upper plate, a middle plate, and a lower plate, and is provided on one of a lower surface of the upper plate and an upper surface of the middle plate. A wiring groove for accommodating the heating means is formed, and a wiring groove for accommodating the power supply line extending from the heating means is provided on one of the lower surface of the intermediate plate and the upper surface of the lower plate. Is formed.

Further, as set forth in claim 4, an opaque upper surface cover member is provided on the upper surface of the mounting table. According to this, since the opaque heat equalizing plate is provided on the upper surface of the mounting table, it is possible to improve the in-plane uniformity of the temperature distribution of the object to be processed.
Further, for example, as set forth in claim 5, the mounting table has a backside gas hole for supplying a gas for purging on an upper surface of the mounting table, and the backside gas hole has a lower portion of a column. A quartz tube for supplying gas from is connected.

In addition, for example, the quartz tube is positioned outside the column, and upper and lower ends thereof are attached and fixed by welding.
Further, for example, the quartz glass is a transparent quartz glass.
Further, as set forth in claim 8, a heat-resistant opaque back cover member is provided on the lower surface side of the mounting table.
As described above, since the heat-resistant opaque back cover member is provided on the lower surface side of the mounting table on which the object to be processed is mounted, the surface (lower surface) of the opaque back cover member is, for example, mottled (irregular). Even if an unnecessary film adheres, the emissivity from the surface of the opaque back cover member is kept substantially uniform in the plane, and therefore, the in-plane uniformity of the surface temperature of the mounting table and the in-plane High temperature uniformity can be maintained.

In this case, for example, the opaque back cover member is made of opaque quartz glass.
Further, for example, as set forth in claim 10, a heat-resistant cover member is provided on each of the upper surface, the side surface, and the lower surface of the mounting table.
As described above, since the heat-resistant cover members are provided on the upper surface, the side surface, and the lower surface of the mounting table on which the object to be processed is mounted, it is possible to prevent metal atoms and the like causing the contamination from being thermally diffused from the mounting table. Therefore, it is possible to prevent various types of contamination such as metal contamination from occurring.
Further, since the material of the mounting table, its side surface, and the lower surface cover member is made of, for example, quartz, it is possible to reduce the generation of contamination such as metal contamination due to heat diffusion from these components. Further, deposition gas can be prevented from adhering to the mounting table. Thereby, the wet cleaning cycle of the mounting table can be extended, so that a long lifetime and an initial shape can be secured.

In addition, for example, a heat-resistant cover member is provided on a side surface of the column, as defined in claim 11.
According to this, since the cover member is also provided on the column of the mounting table, not only metal contamination can be prevented, but also deposition gas deposition on the column can be prevented.
Further, for example, as defined in claim 12, the cover member includes an upper surface cover member, a peripheral edge cover member, a lower surface cover member, and the column cover member, and the lower surface cover member and the column cover member. Are integrally formed, and the entire cover member can be disassembled and assembled.
According to this, since each cover member can be disassembled and assembled, maintenance work such as wet cleaning processing can be performed quickly.

Further, for example, as defined in claim 13, the cover member formed on the upper surface of the mounting table and the other cover member except the opaque back cover member are each made of transparent quartz glass, and the cover member of the transparent quartz glass is The surface has been subjected to a surface roughening treatment for preventing the film adhering thereto from peeling off.
This can prevent the unnecessary film adhering to the surface of the cover member from easily peeling off, so that a maintenance work cycle such as a cleaning process can be lengthened accordingly.
Further, for example, as defined in claim 14, a seal member is provided at a joint portion at a lower end portion of the column, and near the seal member, heat released from the mounting table side to the seal member is provided. An opaque member is provided to block the light.
As a result, the seal member provided at the joint at the lower end of the support column is shielded from radiant heat coming from the mounting table by the opaque member provided in the vicinity thereof, so that it is not damaged by heat.

Further, for example, a lower portion of the support is made of an opaque member.
Further, for example, a quartz glass plate having a smooth surface is joined to a lower end surface of the column.
Further, for example, a cushion member for preventing the breakage is provided at a lower end portion of the column.
Further, for example, by providing an opaque member in the entirety of the support and an opaque member inside the support, the seal member at the lower end of the support is protected from the heat released from the mounting table side.

Also, for example, the opaque upper surface cover member is hermetically covered with a cover member made of transparent quartz glass.
Further, for example, as defined in claim 20, one of the lower surface of the middle plate and the upper surface of the lower plate has a light shielding plate housing portion formed in a concave shape, and Has a thin light shielding plate housed in an airtight manner.
The invention according to claim 21 includes a processing container capable of being evacuated, the mounting table structure described in any one of the above, and gas supply means for supplying a predetermined processing gas into the processing container. A heat treatment apparatus characterized in that:
Further, for example, as defined in claim 22, the heating means of the mounting table includes two inner and outer heating zones.

According to the mounting table structure and the heat treatment apparatus of the present invention, the following excellent operational effects can be exhibited.
According to the inventions according to claims 1 to 3, 5, 6, 7, and 19 to 22, metal atoms or the like causing contamination do not thermally diffuse from the mounting table, and accordingly, various contaminations such as metal contamination. Can be prevented from occurring.
According to the fourth aspect of the present invention, since the opaque heat equalizing plate is provided on the upper surface of the mounting table, the in-plane uniformity of the temperature distribution of the object can be improved.
According to the eighth and ninth aspects of the present invention, since the heat-resistant opaque back cover member is provided on the lower surface side of the mounting table on which the object to be processed is mounted, the surface (lower surface) of the opaque back cover member is provided. For example, even when an unnecessary film adheres in a mottled (irregular shape), the emissivity from the surface of the opaque back cover member is kept substantially uniform in the surface, and therefore, the surface temperature of the mounting table is uniform in the surface. The uniformity of the properties and the in-plane temperature of the object to be processed can be kept high.

According to the tenth aspect of the present invention, since the heat-resistant cover members are provided on the upper surface, the side surface, and the lower surface of the mounting table on which the object to be processed is mounted, respectively, metal atoms and the like that cause contamination from the mounting table are provided. Can be prevented from being thermally diffused, so that various contaminations such as metal contamination can be prevented from occurring.
According to the eleventh aspect of the present invention, since the cover member is also provided on the column of the mounting table, it is possible to further suppress the occurrence of various types of contamination such as metal contamination.
According to the twelfth aspect of the present invention, since each cover member can be disassembled and assembled, maintenance work such as wet cleaning processing can be performed quickly.

According to the thirteenth aspect, it is possible to prevent the unnecessary film adhered to the surface of the cover member from easily peeling off, and accordingly, it is possible to lengthen a maintenance work cycle such as a cleaning process.
According to the invention according to Claims 14 to 16, the seal member provided at the joint at the lower end of the column blocks radiant heat coming from the mounting table side by the opaque member provided in the vicinity thereof. I will not receive it.
According to the seventeenth aspect of the present invention, the cushion member is provided at the lower end of the column, so that damage to this portion can be prevented.
According to the eighteenth aspect, the seal member at the lower end of the support can be protected from heat radiation from the mounting table.

Hereinafter, an embodiment of a mounting table structure and a heat treatment apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
1 is a cross-sectional configuration diagram showing a heat treatment apparatus according to the present invention, FIG. 2 is a cross-sectional view showing a mounting table structure, FIG. 3 is a partially enlarged cross-sectional view showing a lower end portion of a support in FIG. 2, and FIG. FIG. 5 is an exploded view showing a part of the mounting table before joining, and FIG. 6 is an exploded view showing a cover member covering the mounting table.
As shown in the figure, the heat treatment apparatus 2 has, for example, a processing vessel 4 made of aluminum and having a substantially circular cross section. A shower head 6 serving as a gas supply means for introducing a necessary processing gas, for example, a film forming gas, is provided on a ceiling portion of the processing container 4. The processing gas is blown out from the gas injection hole toward the processing space S.

  Inside the shower head 6, two hollow gas diffusion chambers 12A and 12B are formed. After the processing gas introduced therein is diffused in a plane direction, each gas diffusion chamber 12A is diffused. , 12B are respectively blown out from the gas injection holes 10A, 10B. That is, the gas injection holes 10A and 10B are arranged in a matrix. The entirety of the shower head 6 is made of, for example, a nickel alloy such as nickel or Hastelloy (registered trademark), aluminum, or an aluminum alloy. Note that the shower head 6 may have a single gas diffusion chamber. A sealing member 14 made of, for example, an O-ring is interposed at a joint between the shower head 6 and the upper opening of the processing container 4, so that the airtightness in the processing container 4 is maintained. ing.

In addition, a loading / unloading port 16 for loading / unloading a semiconductor wafer W as an object to be processed into / from the processing vessel 4 is provided on a side wall of the processing vessel 4, and the loading / unloading port 16 can be opened and closed in an airtight manner. A gate valve 18 is provided.
An exhaust space 22 is formed in the bottom 20 of the processing container 4. Specifically, a large opening 24 is formed in the center of the container bottom 20. A cylindrical partition wall 26 having a bottomed cylindrical shape extending downward is connected to the opening 24, and the above-described inside is formed therein. An exhaust trapping space 22 is formed. At the bottom 28 of the cylindrical partition wall 26 that partitions the exhaust trapping space 22, there is provided a mounting table structure 29 that stands upright from the bottom and is characterized by the present invention. More specifically, the mounting table structure 29 mainly includes a cylindrical support 30 made of, for example, transparent quartz glass, and a mounting table 32 that is fixedly joined to the upper end. Details of the mounting table structure 29 will be described later.

  The entrance opening 24 of the exhaust trapping space 22 is set to be smaller than the diameter of the mounting table 32, and the processing gas flowing outside the peripheral portion of the mounting table 32 flows below the mounting table 32. At the inlet opening 24. An exhaust port 34 is formed in the lower side wall of the cylindrical partition wall 26 so as to face the exhaust trapping space 22. The exhaust port 34 has an exhaust pipe provided with a vacuum pump (not shown). 36 is connected so that the atmosphere in the processing container 4 and the exhaust space 22 can be evacuated and evacuated.

A pressure regulating valve (not shown), which can control the opening degree, is provided in the middle of the exhaust pipe 36. By automatically adjusting the valve opening degree, the pressure in the processing vessel 4 is reduced. The pressure can be maintained at a constant value or quickly changed to a desired pressure.
Further, the mounting table 32 has a resistance heater 38 made of, for example, a carbon heater embedded in, for example, a predetermined pattern inside as a heating means, and the outside thereof is made of, for example, transparent quartz glass as described later. On the upper surface of the mounting table 32, a thin disk-shaped upper surface cover member 72 made of, for example, SiC is removably mounted, and a semiconductor wafer W as an object to be processed can be mounted on the upper surface. It has become. Further, the resistance heater 38 is connected to a power supply line 40 provided in the column 30 so as to be able to supply power while controlling the power. The power supply line 40 is inserted into the quartz tube 39 (see FIG. 4). The resistance heater 38 is divided into, for example, an inner zone and an outer zone that concentrically surrounds the outer zone, and the power can be individually controlled for each zone. Although only two power supply lines 40 are shown in the illustrated example, four power supply lines 40 are actually provided.

  The mounting table 32 is formed with a plurality of, for example, three pin insertion holes 41 penetrating in the vertical direction (only two are shown in FIG. 1), and can be moved up and down into each of the pin insertion holes 41. And a push-up pin 42 inserted in a loosely fitted state. At the lower end of the push-up pin 42, a circular ring-shaped push-up ring 44 made of ceramics such as alumina is arranged, and the lower end of each of the push-up pins 42 rides on the push-up ring 44. The arm 45 extending from the push-up ring 44 is connected to a retractable rod 46 provided through the container bottom 20, and the retractable rod 46 can be moved up and down by an actuator 48. Thus, each push-up pin 42 is made to protrude upward from the upper end of each pin insertion hole 41 when the wafer W is transferred. An extendable bellows 50 is interposed at the penetrating portion of the retractable rod 46 of the actuator 48 at the bottom of the container, so that the retractable rod 46 can move up and down while maintaining the airtightness in the processing container 4. ing.

  As shown in FIG. 2, a flange 52 having an enlarged diameter is formed at the lower end of the cylindrical column 30 made of, for example, transparent quartz glass for supporting and fixing the mounting table 32. 2, illustration of the internal structure of the mounting table 32, the push-up pins 42, and the like is omitted. An opening 54 having a predetermined size is formed at the center of the bottom portion 28. A base plate 56 made of, for example, an aluminum alloy having a diameter slightly larger than the opening 54 is bolted so as to close the opening 54 from the inside thereof. It is fastened and fixed by 58. A sealing member 60 such as an O-ring is provided between the upper surface of the bottom portion 28 and the lower surface of the base plate 56 to maintain the airtightness of this portion.

  Then, the support 30 is erected on the base plate 56, and a ring-shaped holding member 62 made of, for example, an aluminum alloy and having a L-shaped cross section is fitted to the flange portion 52 of the support 30. By fixing the base 62 and the base plate 56 with bolts 64, the flange 52 is sandwiched and fixed by the holding member 62. At this time, no particles are generated between the upper surface of the flange portion 52 and the joining surface of the pressing member 62, and furthermore, for example, a circular ring-shaped carbon sheet having a cushioning function and having a thickness of about 0.5 mm, for example. The cushion member 63 is interposed to prevent the flange portion 52 from being damaged. Here, for example, a sealing member 66 such as an O-ring is interposed between the upper surface of the base plate 56 and the lower surface of the flange portion 52 to maintain the airtightness of this portion. One large insertion hole 68 is formed in the base plate 56, and the power supply line 40 is drawn out through the insertion hole 68. Accordingly, the inside of the cylindrical column 30 is in an atmospheric pressure atmosphere, but the inside of the column 30 may be sealed.

  Next, a specific configuration of the mounting table structure 29 will be described. As described above, the mounting table 32 and the support 30 of the mounting table structure 29 are both formed of a material having excellent heat resistance and corrosion resistance, for example, transparent quartz glass. Then, an upper surface cover member 72, a peripheral edge cover member 74, a lower surface cover member 76, a column cover member 78, a leg cover member 80, and an opaque rear cover member 82 are provided so as to cover the mounting table 32 and the column 30. I have. The cover member will be described later. Specifically, as shown in FIG. 5, the mounting table 32 has a three-layer configuration in which an upper plate 100A, a middle plate 100B, and a lower plate 100C are stacked in this order and joined by welding. ing. On the upper plate 100A, the thin upper cover member 72 made of an opaque material such as SiC is detachably mounted as described above. On the upper surface side of the middle plate 100B, a wiring groove 102 drawn over the entire surface is formed, and a resistance heater 38 made of, for example, a carbon heater is arranged in the wiring groove 102 along the groove 102. Is established. Here, the resistance heater 38 is arranged, for example, concentrically in a plurality of zones. The wiring groove 102 may be formed on the lower surface of the upper plate 100A. The resistance heater 38 may be arranged in upper and lower layers to form a two-layer structure. In this case, a quartz plate is further stacked according to the number of heater layers.

  Wiring holes 103 are formed in the middle plate 100B and the lower plate 100C to allow power supply lines to pass through necessary portions, and wiring grooves 105 for accommodating the power supply lines are formed in the lower surface of the middle plate 100B. Are formed toward the center of the mounting table 32. The wiring groove 105 may be provided on the upper surface of the lower plate 100C. Then, after the resistance heater 38 and the power supply line 40 are disposed in the wiring grooves 102 and 105 and the wiring hole 103 while being bent, the upper plate 100A, the middle plate 100B, and the lower plate 100C are respectively moved as described above. The mounting table 32 is formed by welding and integrating. The upper end of a cylindrical support 30 made of, for example, transparent quartz glass is welded to the center of the lower surface of the mounting table 32 to integrate them.

  The power supply lines 40 are gathered at the center of the mounting table 32 and extend below substantially the center of the mounting table 32. The feed line 40 extending downward is inserted into, for example, a quartz tube 39. The upper end of the quartz tube 39 is also welded to the lower surface of the lower plate 100C. Further, a thermocouple housing hole 104 is formed so as to penetrate the lower plate 100C and the middle plate 100B and reach the upper plate 100A, and a thermocouple 106 for temperature control is formed in the thermocouple housing hole 104. Provided.

  Further, a backside gas hole 108 for supplying a purge gas through the lower plate 100C, the middle plate 100B, and the upper plate 100A is formed. A gas pipe 110 (see FIG. 4) made of, for example, a transparent quartz pipe extending downward is connected. In this case, the gas outlet at the upper end of the backside gas hole 108 is located at a substantially central portion of the mounting table 32, so that the gas can be substantially evenly distributed toward the peripheral portion. In the vicinity of the joint at the lower end of the support 30, seal members 60 and 66 (see FIG. 2) such as O-rings interposed at the joint are protected from heat radiated from the mounting table 32. The opaque member 112 is provided to block the heat. Specifically, first, a cylindrical first opaque member 112A made of, for example, opaque quartz glass is interposed in the middle of the column 30 by welding. The length of the first opaque member 112A is set to, for example, about 70 mm.

  A second opaque member 112B in the form of a disc made of, for example, opaque quartz glass is fitted inside the first opaque member 112A. Further, a ring-shaped third opaque member 112C made of, for example, opaque quartz glass is provided directly above the seal members 60 and 66 so as to directly contact and support the lower end portion of the column cover member 78. ing. The first to third opaque members 112A to 112C block heat (radiation heat) radiated from the mounting table 32 and directed to the seal members 60 and 66, so that the seal members 60 and 66 are heated. It is designed to prevent damage. Here, the opaque quartz glass refers to quartz glass capable of blocking heat rays and radiant heat. For example, the opaque quartz glass may be not only quartz glass which is made opaque by including many fine bubbles but also colored quartz glass. Further, the entire support may be made of opaque quartz glass. The holding member 62 and the third opaque member 112C are formed with a groove through which a gas pipe serving as the gas passage 114 passes. In addition, when the gas pipe 110 is put out of the column 30, the upper end of the gas pipe 110 is welded to the mounting table 32 and the lower end is welded to the flange 52, so that the upper and lower ends can be strongly supported. . Further, since the gas pipe 110 is provided outside the support 30, a plurality of power supply lines 40 can be accommodated in the support 30. A gas passage 114 communicating with the gas pipe 110 is formed in the bottom 28 and the base plate 56.

  Next, the cover member will be described. Specifically, as shown in FIG. 6, the cover member includes a disk-shaped upper cover member 72 on which the semiconductor wafer W on the upper surface of the mounting table 32 is mounted, and a peripheral portion of the mounting table 32. A ring-shaped peripheral edge cover member 74 covering part or all of the side surface thereof; a lower surface cover member 76 covering part or all of the side surface of the mounting table 32 and the lower surface of the mounting table 32; And a leg cover member 80 that covers the lower end of the column 30 are provided. The upper surface of the peripheral portion of the upper surface cover member 72 supports the upper end of the peripheral portion cover member 74. In this embodiment, in particular, a ring-shaped opaque back cover member 82 is provided in direct contact with the lower surface (back surface) of the mounting table 32 and interposed between the lower surface cover member 76 and the lower surface. Can be Accordingly, in this case, the lower surface cover member 76 covers the lower surface of the opaque rear surface cover member 82.

  All the cover members 72, 74, 76, 78, 80, 82 are made of a heat-resistant and corrosion-resistant material. In particular, since the upper surface cover member 72 directly mounts the wafer W on the upper surface, there is very little risk of contamination such as metal contamination, and a material having good thermal conductivity, for example, high-purity material. It is made of ceramic such as SiC. In addition, the opaque back cover member 82 is made of a material that is unlikely to cause contamination such as metal contamination and hardly transmits heat rays, for example, opaque quartz glass. Further, the other cover members 74, 76, 78, 80 are made of a material that is unlikely to cause metal contamination or the like, for example, transparent quartz glass.

The upper surface cover member 72 made of SiC having good conductivity is formed in a disk shape, and has an accommodation recess 84 for directly mounting the wafer W in the center thereof. Is substantially equal to the thickness of the wafer W. The peripheral portion 85 of the upper surface cover member 72 is formed to be low like a step. The peripheral portion 85 of the upper surface cover member 72 is formed to be low like a step. The upper surface cover member 72 covers substantially the entire upper surface of the mounting table 32. The upper cover member 72 has a pin insertion hole 41 through which the push-up pin 42 (see FIG. 1) passes. The thickness of the upper cover member 72 is, for example, about 6.5 mm.
The peripheral edge cover member 74 made of transparent quartz glass is formed in a ring shape, and as described above, the cross section is inverted L so as to cover the peripheral edge of the upper surface of the mounting table 32 and part or all of the side surface. As shown in FIG. 2, it can be detachably mounted on the peripheral portion of the mounting table 32 by being fitted from above the upper surface cover member 72. Then, the lower surface of the upper end portion of the peripheral edge cover member 74 is brought into contact with the upper surface of the peripheral edge portion 85 of the upper surface cover member 72 so that the peripheral edge cover member 74 is detachably (disassembly) supported. Has become. The thickness of the peripheral portion cover member 74 is, for example, about 3 mm.

  The lower cover member 76 made of transparent quartz glass and the column cover member 78 made of transparent quartz glass are integrally formed by welding. First, as described above, the lower surface cover member is formed in a circular container shape so as to cover part or all of the side surface of the mounting table 32 and the entire lower surface of the mounting table 32. An opening 88 is formed to pass through 30 (see FIG. 2). The upper end of the column cover member 78 is welded to the periphery of the opening 88. The entire mounting table 32 can be removably accommodated in the container-like lower cover member 76. In this case, the inner diameter of the side wall of the peripheral edge cover member 74 is set slightly larger than the outer diameter of the side wall of the lower surface cover member 76, and as shown in FIG. The lower end of the lower cover member 76 is detachably fitted so that both ends thereof slightly overlap with each other so as to contact the outer peripheral surface of the upper end of the side wall of the lower surface cover member 76.

  Thereby, the side surface of the mounting table 32 is completely covered. The lower cover member 76 has a pin insertion hole 41 for inserting the push-up pin 42 (see FIG. 1). The inner diameter of the column cover member 78 integrally joined to the lower surface cover member 76 is set slightly larger than the outer diameter of the column 30, specifically, the flange portion 52. , Reaches the upper surface of the pressing member 62 (see FIG. 2). Here, as described above, in a state where the lower surface cover member 76 and the column cover member 78 are integrally connected, the mounting table 32 can be pulled upward when the mounting table 32 is disassembled. The thickness of the lower surface cover member 76 and the column cover member 78 is, for example, about 3 to 5 mm.

The leg cover member 80 made of transparent quartz glass has an inverted L-shaped cross section so as to cover the exposed surface of the pressing member 62 and the exposed surface of the base plate 56, and is formed in a ring shape as a whole. ing. The thickness of the leg cover member 80 is, for example, about 2.75 to 7.85 mm.
The diameter of the flange 52 is set slightly smaller than the inner diameter of the support cover member 78. When the bolts 58 and 64 are loosened to remove the base plate 56 and the holding member 62, the support cover member 78 is removed. The strut 30 in 78 can be pulled out upward and disassembled.

  On the other hand, the opaque back cover member 82 is formed in a disk shape so as to cover substantially the entire lower surface (back surface) of the mounting table 32 (excluding the connection portion with the support 30), and has a central portion. An opening 90 through which the post 30 passes is formed. Further, a pin insertion hole 41 for inserting the push-up pin 42 is formed in the opaque back cover member 82. As described above, the opaque back cover member 82 is interposed between the lower surface of the mounting table 32 and the lower cover member 76 while being supported at three points by protrusions (not shown). As described above, the opaque back cover member 82 is made of, for example, opaque quartz glass containing a number of fine bubbles and made opaque, and prevents the heat rays from the lower surface of the mounting table 32 from being transmitted outward. It can be stopped.

  In this embodiment, the surfaces of the cover members made of the transparent quartz glass, that is, the peripheral edge cover member 74, the lower surface cover member 76, the support cover member 78, and the leg cover member 80 are previously roughened by sandblasting or the like. The treatment is performed, and fine irregularities are formed on the surface, so that an unnecessary film adhered to the surface is hardly peeled off by the anchor effect.

Next, the operation of the heat treatment apparatus configured as described above will be described.
First, an unprocessed semiconductor wafer W is loaded into the processing chamber 4 via the gate valve 18 and the loading / unloading port 16 which are held by a transfer arm (not shown) and opened, and the wafer W is pushed up. After being transferred to the pins 42, the push-up pins 42 are lowered to place the wafer W on the upper surface of the mounting table 32, specifically, on the accommodation recess 84 on the upper surface of the upper surface cover 72 to support it. .

Next, when a Ti film, for example, is deposited as a processing gas on the shower head 6, each film forming gas such as TiCl ₄ , H ₂ , and NH ₃ is used. When a TiN film is deposited, TiCl ₄ , NH Each of the film forming gases such as _{3 is} supplied while controlling the flow rate, and this gas is blown out from the gas injection holes 10 to be injected and introduced into the processing space S. Then, by continuing to drive a vacuum pump (not shown) provided in the exhaust pipe 36, the atmosphere in the processing container 4 and the exhaust space 22 is evacuated, and the opening degree of the pressure regulating valve is reduced. Is adjusted to maintain the atmosphere in the processing space S at a predetermined process pressure. At this time, the temperature of the wafer W is maintained at, for example, about 500 to 600 ° C. As a result, a thin film such as a Ti film or a TiN film is formed on the surface of the semiconductor wafer W.

  In such a film forming process, in the case of the conventional apparatus, a very small amount of heavy metal or the like contained therein is thermally diffused from a mounting table made of, for example, an AlN material, which is heated to a high temperature. There is a risk of being released inward. However, in the present embodiment, the material forming the mounting table 32 and the support columns 30 is formed of transparent quartz glass having heat resistance and corrosion resistance and containing almost no heavy metal or the like. Good heat conduction and prevention of contamination such as metal contamination can be prevented. Further, the entire surface of the mounting table 32 has a high heat resistance and is free from contamination such as metal contamination, for example, the upper surface cover member 72 formed of SiC. Since it is completely covered with the peripheral edge cover member 74 and the lower surface cover member 76 made of transparent quartz glass which is a material free from contamination such as contamination, it is possible to prevent heavy metals and the like from diffusing into the processing vessel 4. Therefore, it is possible to more reliably prevent the semiconductor wafer W from being contaminated with metal. In this case, even if only the above three cover members, that is, the upper surface cover member 72, the peripheral edge cover member 74, and the lower surface cover member 76 are provided, a sufficient effect of preventing contamination such as metal contamination can be obtained.

In this embodiment, the support 30 is formed of transparent quartz glass as described above, and the support 30 is completely covered by a support cover member 78 made of, for example, quartz glass. The effect of preventing contamination can be further improved. In addition, since the surfaces of the holding member 62 and the base plate 56 for fixing the lower end of the support 30 are also covered by the leg cover member 80 made of transparent quartz glass, the effect of preventing contamination such as metal contamination is further improved. Can be done.
Further, since the upper surface cover member 72 interposed between the mounting table 32 and the wafer W is formed of a material having better heat conductivity than transparent quartz glass, for example, SiC, it is embedded in the mounting table 32. It is possible to efficiently transfer the heat from the resistance heater 38 to the wafer W and efficiently heat it. Since the transparent quartz glass has better thermal conductivity than the opaque quartz glass, the heat transfer loss can be reduced by forming the mounting table 32 of the transparent quartz glass.

In this case, since the opaque upper surface cover member 72 made of, for example, SiC is provided on the upper surface of the mounting table 32, the temperature distribution generated in the resistance heater 38 is not projected on the wafer W side. The in-plane uniformity of the temperature of the wafer W can be further improved. That is, the upper surface cover member 72 also has the function of a heat equalizing plate.
In addition, as the film forming apparatus advances, not only a required film desired to be deposited on the surface of the wafer W, but also an unnecessary film adheres to the exposed surfaces of the cover members 72, 74, 76, 78, and 80. That is inevitable. In this case, in this embodiment, since the surface of each of the cover members 72, 74, 76, 78, and 80 is subjected to surface roughening treatment to form fine irregularities, the unnecessary film is not attached. In this case, the unnecessary film hardly peels off due to the anchor effect due to the fine unevenness. Accordingly, the maintenance cycle such as the cleaning process can be lengthened accordingly, and the operation rate of the apparatus can be improved.

  Further, during the film forming process, an unnecessary film tends to adhere to the lower surface of the mounting table 32, that is, the lower surface of the lower surface cover member 76 in this case. Although the film caused the distribution of the radiant heat from the mounting table, in the case of the present embodiment, the ring-shaped opaque back cover was formed over the entire lower surface of the mounting table 32 at a distance of about 1 to 2 mm. Since the member 82 is provided, even if the unnecessary film adheres in a mottled manner, the distribution of radiant heat from the mounting table 32 does not occur. Therefore, the temperature distribution of the mounting table 32 is a target temperature distribution, for example, Since the in-plane uniformity is maintained, the in-plane uniformity of the temperature of the wafer W can be improved.

If the temperature of the resistance heater 38 can be adjusted for each zone as in the present invention, it is possible to reduce the necessity of temperature tuning during the film forming process. In addition, since quartz glass has little thermal expansion, there is no possibility of breakage due to a temperature difference between zones, and zone heating can be performed freely. Further, since the opaque back cover member 82 can suppress emission of radiant heat, the thermal efficiency of the resistance heater 38 can be increased accordingly.
Further, here, two cover members of the lower surface cover member 76 and the opaque rear cover member 82 are provided on the lower surface side of the mounting table 32, but the present invention is not limited to this, and the installation of the lower surface cover member 76 is omitted, and The opaque back cover member 82 may be directly welded to the upper end of the cover member 78 to integrate them.

In the case of the cleaning process, the wet cleaning or the dry cleaning may be performed only on each of the cover members 72, 74, 76, 78, and 80, so that the maintainability can be improved.
Further, in this embodiment, the entire mounting table 32 is made of transparent quartz glass having a smaller coefficient of thermal expansion than a ceramic such as AlN used for the conventional mounting table, so that the heat treatment temperature is higher than that of the conventional apparatus. Heat resistance up to temperature can be improved. That is, since quartz having low thermal expansion is used as the material of the mounting table 32, even if the power difference applied to each zone becomes large, it is not damaged. For example, as a result of an experiment, in the case of the conventional mounting table made of AlN, the mounting table was broken at about 700 ° C., but in the case of the mounting table 32 made of transparent quartz glass of the present invention, the processing temperature was set to about 720 ° C. No damage was observed even when the temperature was raised to the maximum. In particular, in order to optimize the temperature distribution of the mounting table 32, the power ratio applied between the inner zone and the outer zone of the mounting table 32 may be different, but the input power to the inner zone and the input power to the outer zone are sometimes different. An experiment was performed in which the power ratio (input power to the inner zone / input power to the outer zone) was changed over a wide range of about 0.2 to 1, but the mounting table 32 was subjected to a heat treatment in the range of 400 to 720 ° C. Was not damaged. Although the temperature of the mounting table 32 was further increased, it was not broken up to 1200 ° C.

At this time, the in-plane uniformity of the temperature distribution of the mounting table 32 in the above temperature range was also evaluated. The result at this time is shown in FIG. Note that the process pressure is changed in a range of 10 ^{−1 to} 666 Pa. As is clear from FIG. 7, the in-plane uniformity of the temperature distribution is ± 0.7% or less (average ± 0.5%) over the range of 400 to 720 ° C. In this case, since it was about ± 1.2%, it could be confirmed that the same or better good in-plane uniformity of the temperature distribution could be realized.
Further, since a plurality of quartz glass plates are stacked and the resistance heater 38 is embedded therein, the feeder line 40 can be pulled out from the center of the mounting table 32 downward. Further, by mounting the mounting table 32 with a plurality of glass plates 100A, 100B, and 100C, the mounting table 32 can be completely separated from the inside of the processing container 4. Further, by purging the backside gas on the upper surface of the mounting table 32, it is possible to prevent film formation on the upper surface of the mounting table 32, the lower surface of the upper surface cover member 72, and the thermocouple housing hole 104.

  In the above-described embodiment, the cover member is provided on the mounting table 32 and the column 30. However, the present invention is not limited to this, and the cover member may be provided as in a modified example of the mounting table structure of the present invention shown in FIG. It may not be provided. That is, as shown in FIG. 8, the mounting table structure does not include the peripheral edge cover member 74, the lower surface cover member 76, the column cover member 78, and the leg cover member 80 shown in FIG. However, an opaque back cover member 82 is provided on the lower surface of the mounting table 32, and even if an unnecessary film adheres to the lower surface of the cover member 82 in a mottled manner, the unnecessary heat is applied to the mounting table 32 side. It is designed to prevent adverse effects. Also in this case, an upper surface cover member 72 is provided on the upper surface side of the mounting table 32 to improve the in-plane uniformity of the wafer temperature.

Further, in the case of the embodiment shown in FIG. 8, the exposed surface of the transparent quartz glass of the mounting table 32 and the support 30 may be subjected to a surface roughening treatment by sandblasting or the like in advance to take measures against particles.
In the embodiment shown in FIGS. 2 and 8, opaque quartz glass may be used instead of transparent quartz glass as a material forming the mounting table 32 and the support column 30, or only the lower plate 100C is made of opaque quartz glass. May be replaced by According to this, the opaque back cover member 82 provided on the lower surface of the mounting table 32 can be eliminated.

  Further, here, as shown in FIGS. 2 and 8, the first opaque member 112 </ b> A is provided as an opaque member in the middle of the column 30 to protect the seal member from heat. However, the present invention is not limited to this. , As shown in FIG. FIG. 9 is a partial cross-sectional view showing a state in which an opaque member is provided at the lower part of the column.

  First, in the case shown in FIG. 9A, the entire flange portion 52 of the column 30 is formed of a fourth opaque member 112D, for example, opaque quartz glass. In this case, since fine irregularities due to bubbles are generated on the surface of the opaque quartz glass as described above, even if this lower surface is directly joined to the surface of the base plate 56 via the sealing member 66, It is conceivable that the sealability is degraded by the fine irregularities. Therefore, here, a quartz glass plate 120 having a thickness of about 2 to 3 mm with both upper and lower surfaces smoothed is joined to the lower end surface of the support column 30 by fusion or the like. Then, the sealing member 66 is directly in contact with and pressed against the smooth quartz glass plate 120 to ensure high sealing performance.

Further, in order to reliably protect the seal member 66 from heat, as shown in FIG. 9B, the entire lower portion of the support 30 including the flange portion 52 is formed with a fifth opaque member having a predetermined length. 112E, for example, opaque quartz glass. Also in this case, a quartz glass plate 120 is fused to the lower end surface of the column 30 in order to maintain the sealing property. It is sufficient that the length of the fifth opaque member 112E is about の of the entire length of the column 30. For example, if the length of the column 30 is 260 mm, this fifth opaque member 112E is sufficient. The length of the member 112E may be about 130 mm. Even if the length of the fifth opaque member 112E is further increased, the effect of shielding the radiant heat is substantially the same as, for example, the case where the entire column 30 is formed of the opaque member.
By providing the fourth or fifth opaque members 112D and 112E in this manner, radiant heat (light) transmitted through the column 30 can be efficiently blocked, so that thermal damage to the lower seal member 66 is significantly suppressed. In particular, in the case shown in FIG. 9B, it is possible to almost certainly prevent the seal member 66 from being thermally damaged.

Next, another modified example of the present invention will be described.
In the above embodiments, the opaque upper cover member 72 is provided on the upper plate 100A of the mounting table 32, and the wafer W is mounted thereon for processing. Since the process gas is sneak in the gas, the process gas sneaks into a small gap between the upper surface of the upper plate 100A and the lower surface of the upper surface cover member 72, and an unnecessary film is not formed there. It adheres uniformly, and as a result, adversely affects the heating due to the radiant heat, which may degrade the uniformity of the heat distribution in the wafer surface.
Therefore, as shown in FIG. 10, the upper surface cover member 72 may be hermetically covered with a lid member. FIG. 10 is a partial schematic cross-sectional view showing a state where the upper cover member on the mounting table is covered with a lid member. FIG. 10 shows only the basic configuration of the mounting table, and the illustration of the power supply line of the heater and other cover members is omitted.

  As shown in FIG. 10, the diameter of the opaque upper surface cover member 72 is set to be somewhat smaller than the diameter of the upper plate 100A of the lower mounting table 32, and the entire upper surface cover member 72 is made smaller. It is surrounded by a lid member 124 so as to cover it. The lid member 124 is made of, for example, transparent quartz glass, which is the same constituent material as the mounting table 32, and its peripheral portion has a shape that is bent downward. The peripheral portion of the lid member 124 is joined to the upper surface of the peripheral portion of the upper plate 100A over the entire periphery by fusion or the like, and the inside thereof is filled with nitrogen to be in a reduced pressure airtight state. Then, the wafer W is placed on the upper surface of the lid member 124.

In this case, since the upper surface cover member 72 is protected in a sealed state, the process gas does not enter the lower surface side, so that an unnecessary film or the like that causes the in-plane uniformity of the heat distribution to be lost. The uniformity of the heat distribution in the wafer surface can be further enhanced without fear of adhesion. Further, since the upper surface cover member 72 is not exposed to a process gas or the like, a carbon sheet material which is easily responsive to the process gas, for example, can be used alone.
In particular, the carbon sheet material has high purity, and furthermore, it is difficult to conduct heat in the thickness direction, and it is easy to conduct heat in the plane direction. Therefore, contamination from the top cover member (carbon sheet) does not occur during glass fusion. Good fusion can be achieved, and it can further contribute to improvement of in-plane uniformity of wafer temperature.

Next, still another modification of the present invention will be described.
In each of the above embodiments, the opaque quartz cover 82 is separately provided on the lower surface side of the lower plate 100C of the mounting table 32. Alternatively, or together with this, the mounting table 32 may be provided as shown in FIG. May be provided with a light shielding plate inside. FIG. 11 is a diagram showing a state in which the light-shielding plate is provided inside the mounting table in such a manner. FIG. 11 (A) shows a partial schematic cross-sectional view, and FIG. 11 (B) shows A in FIG. 11 (A). FIG. 2 is a view taken in the direction of an arrow A, showing a plan view of a lower plate. FIG. 11 shows only the basic configuration of the mounting table, and the illustration of the power supply line of the heater and other cover members is omitted.

  As shown in FIG. 11, here, a light shielding plate housing 126 is formed in a concave shape on the upper surface side of the lower plate 100C of the mounting table 32. Note that the light shielding plate housing portion 126 may be formed on the lower surface side of the middle plate 100B. In the illustrated example, two left and right light shield plate housing portions 126 are formed in a substantially semicircular shape, and a joining surface having a constant width L2 is formed around the lower plate 100C. Further, a wiring groove 128 for concentrating the power supply line of the heater at the center may be formed in one diameter direction of the upper surface of the lower plate 100C. In the semicircular light-shielding plate housing 126, for example, a black opaque thin light-shielding plate 130 is provided over substantially the entire area. In this case, the peripheral portion of the upper surface of the lower plate 100C is joined to the peripheral portion of the lower surface of the middle plate 100B over the entire periphery by fusion or the like, and nitrogen is sealed in the light shielding plate housing portion 126. It is in a reduced pressure airtight state. Therefore, since the light shielding plate 130 is not exposed to the process gas or the like, for example, as described in FIG. .

Even in this case, even if a film having an unnecessary non-uniform distribution that may break the in-plane uniform distribution of the wafer temperature adheres to the lower surface side of the mounting table 32, the influence of the film on the wafer can be prevented. Therefore, the in-plane uniformity of the wafer temperature can be kept high.
Further, since the radiant heat from the resistance heater 38 is blocked by the light shielding plate 130, unnecessary portions in the processing container can be prevented from being unnecessarily heated, and at the same time, the thermal efficiency of the resistance heater 38 can be improved. Can be enhanced.
In particular, the carbon sheet material has high purity, and it is difficult to conduct heat in the thickness direction, and it is easy to conduct heat in the plane direction. Therefore, contamination from the carbon sheet does not occur during glass fusion, and good fusion is achieved. In addition to this, it is possible to further contribute to the improvement of the in-plane uniformity of the wafer temperature.

Further, in the above embodiment, the film forming process by thermal CVD has been described as an example of the process, but the present invention is not limited to this, and the present invention is also applied to a plasma CVD process device, an etching process device, an oxidation diffusion process device, a sputter process device, and the like. can do.
In this embodiment, a semiconductor wafer has been described as an example of an object to be processed. However, the present invention is not limited to this, and can be applied to an LCD substrate, a glass substrate, and the like.
Here, the transparent quartz is not only transparent on the other side but also transparent through the light of a predetermined value or more without being transparent. The opaque quartz includes not only those that do not transmit light at all, but also those that transmit light only at a predetermined value or less. The predetermined value is based on whether or not the light affects the mounting table or the processing container as heat energy.

FIG. 1 is a cross-sectional configuration diagram illustrating a heat treatment apparatus according to the present invention. It is sectional drawing which shows a mounting table structure. FIG. 3 is a partially enlarged cross-sectional view illustrating a lower end portion of a column in FIG. 2. It is an expanded sectional view showing a part of mounting table. FIG. 4 is an exploded view showing a state before the mounting table is joined. FIG. 4 is an exploded view showing a cover member that covers the mounting table. 6 is a graph showing a temperature distribution of the mounting table in a predetermined temperature range. It is a block diagram which shows the modification of the mounting table structure of this invention. FIG. 7 is a partial cross-sectional view showing a state where an opaque member is provided at a lower portion of a support. It is a partial schematic sectional view showing the state when the upper surface cover member on the mounting table is covered with the lid member. It is a figure showing the state where the light-shielding plate was provided inside the mounting table.

Explanation of reference numerals

Reference Signs List 2 heat treatment apparatus 4 processing vessel 6 shower head section 29 mounting table structure 30 support column 32 mounting table 38 resistance heater (heating means)
60, 66 Seal member 72 Upper surface cover member 74 Peripheral edge cover member 76 Lower surface cover member 78 Prop cover member 80 Leg cover member 82 Opaque rear cover member 112, 112A, 112B, 112C Opaque member W Semiconductor wafer (workpiece)

Claims (22)

A mounting table on which the object to be processed is mounted in order to perform a predetermined heat treatment on the object in the processing container; and a support having a support for supporting the mounting table upright from the bottom of the processing container. In the table structure,
The mounting table structure, wherein the mounting table and the support are each formed of quartz glass, and a heating unit is embedded in the mounting table.   The column is formed in a cylindrical shape, and a power supply line for the heating means is drawn out from a center portion of the mounting table, and is inserted downward in the cylindrical column. Item 4. The mounting table structure according to Item 1.   The mounting table is formed by joining an upper plate, a middle plate, and a lower plate, and one of a lower surface of the upper plate and an upper surface of the middle plate has a wiring groove for accommodating the heating unit. Wherein a wiring groove for accommodating the power supply line extending from the heating means is formed on one of a lower surface of the middle plate and an upper surface of the lower plate. 3. The mounting table structure according to 1 or 2.   The mounting table structure according to claim 1, wherein an opaque upper surface cover member is provided on an upper surface of the mounting table.   The mounting table has a backside gas hole for supplying a gas for purging on the upper surface of the mounting table, and a quartz tube for supplying a gas is connected to the backside gas hole. The mounting table structure according to any one of claims 1 to 4, wherein:   6. The mounting table structure according to claim 5, wherein the quartz tube is located outside the column, and upper and lower ends thereof are attached and fixed by welding.   The mounting table structure according to claim 1, wherein the quartz glass is a transparent quartz glass.   The mounting table structure according to any one of claims 1 to 7, wherein a heat-resistant opaque back cover member is provided on a lower surface side of the mounting table.   9. The mounting table structure according to claim 8, wherein said opaque back cover member is made of opaque quartz glass.   The mounting table structure according to any one of claims 1 to 9, wherein a heat-resistant cover member is provided on each of an upper surface, a side surface, and a lower surface of the mounting table.   The mounting table structure according to claim 10, wherein a heat-resistant cover member is provided on a side surface of the column.   The cover member includes an upper surface cover member, a peripheral edge cover member, a lower surface cover member, and the column cover member, and the lower surface cover member and the column cover member are integrally formed, and the cover The mounting table structure according to claim 10, wherein the entire member can be disassembled and assembled.   The cover member formed on the upper surface of the mounting table and the other cover members except for the opaque back cover member are each made of transparent quartz glass, and the surface of the transparent quartz glass cover member is peeled of a film attached thereto. The mounting table structure according to any one of claims 10 to 12, wherein a surface roughening treatment is performed to prevent the mounting table.   A seal member is provided at the joint at the lower end of the support, and an opaque member is provided near the seal member for blocking heat released from the mounting table side to the seal member. The mounting table structure according to any one of claims 1 to 13, wherein:   The mounting table structure according to any one of claims 1 to 14, wherein a lower portion of the support is made of an opaque member.   The mounting table structure according to claim 15, wherein a quartz glass plate having a smooth surface is joined to a lower end surface of the support.   The mounting table structure according to any one of claims 1 to 16, wherein a cushion member for preventing the breakage is interposed at a lower end portion of the support column.   18. The opaque member as a whole of the support and an opaque member provided inside the support to protect a seal member at a lower end of the support from heat released from the mounting table side. The mounting table structure described in Crab.   19. The mounting table structure according to claim 4, wherein the opaque upper cover member is air-tightly covered by a cover member made of transparent quartz glass.   On one of the lower surface of the middle plate and the upper surface of the lower plate, a light shielding plate housing portion is formed in a concave shape, and a thin light shielding plate is airtightly housed in the light shielding plate housing portion. 20. The mounting table structure according to claim 3, wherein: A processing container that can be evacuated,
A mounting table structure according to any one of claims 1 to 20,
Gas supply means for supplying a predetermined processing gas into the processing container,
A heat treatment apparatus comprising: 22. The heat treatment apparatus according to claim 21, wherein the heating means of the mounting table includes two inner and outer heating zones.

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