JP2014212331A - Vertical heat treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize reduction in a device cost, as well as an effective utilization of a treatment gas when performing a heat treatment in a reaction tube by supplying the treatment gas from the lateral side to each of a plurality of substrates placed on a wafer boat in a shelf form.SOLUTION: A plurality of substrate placing regions 33 are arranged in the circumferential direction on each upper surface side of holding plates 31. These holding plates 31 are held by poles 32 from the peripheral edge side in the circumferential direction at a plurality of positions. Each pole 32 is arranged at a position inward the outer peripheral of the holding plate 31 in such a manner that a gap size t between the outer peripheral of the holding plate 31 and the inner wall of an inner cylinder 12b becomes smaller than a gap size k between the upper surface of a wafer W held on the holding plate 31 and the lower surface of the holding plate 31 opposing from above to the wafer W. Then the treatment gas is supplied to each wafer W from gas discharge ports 52 arranged at each lateral side of the wafer W.

Description

  The present invention relates to a vertical heat treatment apparatus that performs a heat treatment by supplying a processing gas to a plurality of substrates stacked in a shelf on a substrate holder.

  As a heat treatment apparatus for performing a heat treatment such as a film forming process on a substrate such as a semiconductor wafer (hereinafter referred to as “wafer”), about 100 to 150 wafers are stacked on a wafer boat as a substrate holder. At the same time, there is known a batch type vertical heat treatment apparatus in which the wafer boat is stored in a reaction tube in an airtight manner and a film forming gas is supplied into the reaction tube in a vacuum atmosphere to form a thin film. The wafer boat includes a disk-shaped top plate and bottom plate, and support columns that connect the top plate and the bottom plate at a plurality of locations from the outer peripheral side to the circumferential direction. On the side surfaces of these columns, slit-shaped grooves are formed at a plurality of positions in the vertical direction so as to face the storage area of the wafer, and the end portions of each wafer are supported by the grooves of these columns. Stored. Therefore, a gap region is formed in the circumferential direction between the outer peripheral portion of the wafer supported by the wafer boat and the inner wall of the reaction tube so as to correspond to the region where the support column is disposed.

  As a method of supplying a film forming gas into the reaction tube, there is a case where a cross flow method is adopted so that a gas flow is formed in the horizontal direction in each wafer as in Patent Document 1. Specifically, for example, the reaction tube has a double tube structure including an inner tube and an outer tube, and a slit-like exhaust port extending in the vertical direction is formed in the inner tube, and in a vertical direction so as to face the exhaust port. An extending gas injector is placed on the side of the wafer boat. Then, a plurality of gas discharge ports are formed on the side wall of the gas injector so as to correspond to the height position of each wafer, and a gas flow from the gas discharge port toward the exhaust port is formed in each wafer.

  At this time, a gap region is formed in the circumferential direction between the outer peripheral portion of the wafer supported by the wafer boat and the reaction tube (inner tube) as described above, so that the gas is discharged from the gas injector. The film forming gas tends to flow through this gap region rather than a narrow region between the wafers. For this reason, the amount of gas supplied to each wafer becomes smaller than the set value, and the productivity (film formation rate), the uniformity of the film thickness in the surface and the coverage (coverage) may be deteriorated. . Further, if the deposition gas is discharged without contributing to the deposition, the amount of the deposition gas used increases, leading to an increase in cost.

By the way, in recent years, instead of a normal 12 inch (300 mm) size wafer, for example, a silicon carbide (SiC) substrate having a diameter of about 4 inches (100 mm) or a silicon (Si) substrate for solar cells, For example, a process for forming an alumina (Al2O3) film has been studied. For example, a sapphire substrate having an outer diameter of 100 mm is used as the wafer W, a GaN (gallium nitride) film is formed on the wafer W by MO-CVD (Metal Organic Chemical Vapor Deposition), and an LED (Light Emitting) is formed. Diode) devices are also being studied. However, as described above, if these substrates are loaded on a wafer boat in a shelf shape and this process is performed, the substrate size is smaller than that of a 12-inch wafer, and the cost of the apparatus is relatively high. End up. Further, since the height dimension of the wafer boat (vertical heat treatment apparatus) is limited by, for example, the ceiling surface of the clean room, the number of substrates loaded on the wafer boat (the number of slots) is increased in order to reduce the cost of the apparatus. It is difficult.
Patent Documents 2 and 3 describe a technique for arranging wafers W in the circumferential direction on the wafer disk 23b and the susceptor 16, and Patent Document 4 describes an apparatus that performs processing by stacking wafers vertically. However, the above-mentioned problems are not described.

JP 2009-206489 A JP 2010-73823 A Japanese Patent Laid-Open No. 61-136676 JP 2000-208425 A

  The present invention has been made in view of such circumstances, and an object of the present invention is to supply a processing gas from the side to each of a plurality of substrates stacked in a shelf shape on a substrate holder so as to be within a reaction tube. It is an object of the present invention to provide a vertical heat treatment apparatus capable of improving the use efficiency of a processing gas when performing heat treatment.

The vertical heat treatment apparatus of the present invention is
In a vertical heat treatment apparatus for carrying a heat treatment on a substrate by carrying a substrate holder holding a plurality of substrates in a shelf shape into a vertical reaction tube in which a heating unit is arranged around the substrate holder,
A process gas provided along a length direction of the reaction tube and having a gas discharge port formed at a height corresponding to each substrate in order to supply a process gas to each substrate held by the substrate holder A supply section;
An exhaust port formed at a position opposite to the gas discharge port with respect to the center of the reaction tube,
Each of the substrate holders includes a plurality of substrate placement regions, a plurality of circular holding plates stacked on each other, and supports each holding plate through the peripheral edge of the holding plate in the circumferential direction. And a plurality of support columns provided along the outer periphery of the support plate when viewed in the radial direction of the reaction tube.
The specific configuration of the vertical heat treatment apparatus may be as follows.
The distance between the outer edge of the holding plate and the inner wall of the reaction tube is larger than the distance between the upper surface of the substrate supported on the holding plate and the lower surface of the holding plate facing the upper side of the substrate. The configuration is also short.
The outer part of the support column is located at the same position as the outer edge of the holding plate or at the inner side, and is located closer to the inner side than the position protruding 3 mm outward from the outer edge of the holding plate.
The separation dimension between the outer edge of the holding plate and the inner wall of the reaction tube is 8 mm or less.
A configuration in which the outer edge of the substrate on the substrate holder and the outer peripheral surface of the support are aligned on the contour line of the holding plate when viewed in the radial direction of the reaction tube.
The reaction tube includes a first reaction tube that is airtightly opened and closed, and a second reaction tube that is provided inside the first reaction tube and houses the substrate holder,
The processing gas supply unit is a gas injector disposed in the second reaction tube along the length direction of the substrate holder,
The exhaust port is formed in a slit shape on the side surface of the second reaction tube along the length direction of the gas injector so as to face the gas injector,
A configuration in which an exhaust port for exhausting the atmosphere in the region is disposed so as to communicate with the region between the first reaction tube and the second reaction tube.
A configuration comprising a rotation mechanism for rotating the substrate holder around a vertical axis.
The process gas supply unit includes a first gas supply unit that supplies a first process gas to the substrate, and a second gas supply unit that supplies a second process gas that reacts with the first process gas to the substrate. And a third gas supply unit for supplying a purge gas to the substrate,
A control unit is provided that alternately supplies the first processing gas and the second processing gas to the substrate, and outputs a control signal so as to supply the purge gas to the substrate and perform gas replacement when switching between the processing gases. Configuration.
The vertical heat treatment apparatus of the present invention is
In a vertical heat treatment apparatus for carrying a heat treatment on a substrate by carrying a substrate holder holding a plurality of substrates in a shelf shape into a vertical reaction tube in which a heating unit is arranged around the substrate holder,
A process gas provided along a length direction of the reaction tube and having a gas discharge port formed at a height corresponding to each substrate in order to supply a process gas to each substrate held by the substrate holder A supply section;
An exhaust port formed at a position opposite to the gas discharge port with respect to the center of the reaction tube,
The substrate holder includes a plurality of circular holding plates formed in a substrate mounting region and stacked on each other, and supports each holding plate through the peripheral edge of the holding plate. An outer portion of the support column when viewed in the radial direction of the reaction tube, or at the same position as the outer edge of the holding plate, or closer to the inside,
The distance between the outer edge of the holding plate and the inner wall of the reaction tube is larger than the distance between the upper surface of the substrate supported on the holding plate and the lower surface of the holding plate facing the upper side of the substrate. Is also set short.

  The present invention relates to a vertical heat treatment apparatus for performing heat treatment by discharging a processing gas from a gas discharge port formed at a height position corresponding to each substrate to each substrate held by a substrate holder. The holding plates are stacked, a plurality of substrates are held on each holding plate, and the support columns that support the peripheral portions of the plurality of holding plates are configured not to jump out from the outer edge of the holding plate. Therefore, since the gap between the holding plate and the reaction tube can be narrowed, the amount of the processing gas that does not contribute to the processing and passes outside the holding plate can be suppressed. Therefore, it is possible to effectively use the processing gas, in other words, to improve the usage efficiency of the processing gas. In addition, since a plurality of substrates are arranged on each holding plate, the footprint of the device required for one substrate can be suppressed as compared with the case where one substrate is arranged on the holding plate. Cost can be reduced.

It is a longitudinal cross-sectional view which shows an example of the vertical heat processing apparatus of this invention. It is a cross-sectional top view which shows the said vertical heat processing apparatus. It is a perspective view which expands and shows a part of said vertical heat processing apparatus. It is a cross-sectional top view which shows the effect | action in the said vertical heat processing apparatus. It is a partially expanded side view which shows the effect | action of the said vertical heat processing apparatus. It is a cross-sectional top view which shows the effect | action in the said vertical heat processing apparatus. It is a cross-sectional top view which shows the effect | action in the said vertical heat processing apparatus. It is a cross-sectional top view which shows the effect | action in the said vertical heat processing apparatus. It is a partially expanded transverse plan view which shows the other example of the said vertical heat processing apparatus. It is a top view which shows the other example of the said vertical heat processing apparatus. It is a longitudinal cross-sectional view which shows the other example of the said vertical heat processing apparatus. It is a perspective view of the reaction tube which shows the other example of the said vertical heat processing apparatus. It is a top view which shows the other example of the said vertical heat processing apparatus.

  An example of an embodiment of the vertical heat treatment apparatus of the present invention will be described with reference to FIGS. This vertical heat treatment apparatus includes a wafer boat 11 that is a substrate holder made of, for example, quartz for loading wafers W in a shelf shape, and the wafer boat 11 is housed inside to form a film on each wafer W. And a reaction tube 12 made of, for example, quartz for processing. In this example, the wafer W is made of Si (silicon) and has a diameter dimension and a thickness dimension of, for example, 4 inches (100 mm) and 0.75 mm, respectively. A heating furnace main body 14 in which a heater 13 as a heating unit is arranged on the inner wall surface in the circumferential direction is provided outside the reaction tube 12, and the reaction tube 12 and the heating furnace main body 14 extend in the horizontal direction. The lower end portion is supported by the support portion 15 in the circumferential direction.

  In this example, the reaction tube 12 has a double tube structure of an outer tube 12a that is a first reaction tube and an inner tube 12b that is a second reaction tube housed in the outer tube 12a. Each of the outer tube 12a and the inner tube 12b is formed so that the lower surface side is opened. The ceiling surface of the inner tube 12b is formed horizontally, and the ceiling surface of the outer tube 12a is formed in a substantially cylindrical shape so as to bulge outward. The inner tube 12b is formed such that one end side of the side surface swells outward along the length direction of the inner tube 12b, and a gas injector 51 that forms a gas supply unit described later is accommodated in the swelled outside. It is configured to be. In addition, on the surface of the side surface of the inner tube 12b facing the region where the gas injector 51 is accommodated, as shown in FIG. 2, the slit-shaped exhaust port 16 is provided along the length direction of the inner tube 12b. Is formed. That is, the exhaust port 16 is formed at a position opposite to the gas injector 51 (gas discharge port 52) with respect to the center of the reaction tube 12. The processing gas supplied from the gas injector 51 to the inner pipe 12b is exhausted to a region between the inner pipe 12b and the outer pipe 12a through the exhaust port 16. The outer tube 12a and the inner tube 12b are airtightly supported from below by a substantially cylindrical flange portion 17 having a lower end surface formed in a flange shape and an upper and lower surface opened. That is, the outer tube 12 a is airtightly supported by the upper end surface of the flange portion 17, and the inner tube 12 b is airtightly supported by the projecting portion 17 a that protrudes inward from the inner wall surface of the flange portion 17. The inner diameter of the inner tube 12b is, for example, 330 mm.

  An exhaust port 21 is formed on the side wall of the flange portion 17 so as to communicate with a region between the inner tube 12b and the outer tube 12a. An exhaust passage 22 extending from the exhaust port 21 has a butterfly valve or the like. A vacuum pump 24 is connected via the pressure adjusting unit 23. On the lower side of the flange portion 17, there is provided a lid 25 formed in a substantially disc shape so that the outer edge portion is in airtight contact with the flange surface which is the lower end portion of the flange portion 17 in the circumferential direction. The lid 25 is configured to be movable up and down together with the wafer boat 11 by a lifting mechanism such as a boat elevator (not shown). In FIG. 1, reference numeral 26 denotes a heat insulating body formed in a cylindrical shape between the wafer boat 11 and the lid body 25, and 27 denotes a rotating mechanism such as a motor for rotating the wafer boat 11 and the heat insulating body 26 around the vertical axis. . In FIG. 1, reference numeral 28 denotes a rotating shaft that airtightly penetrates the lid 25 and connects the motor 27, the wafer boat 11, and the heat insulator 26, and 21a is an exhaust port.

  Next, the wafer boat 11 will be described in detail. As shown in FIGS. 2 and 3, the wafer boat 11 has a circular shape with a diameter dimension set to, for example, 300 mm in order to place a plurality of, for example, five wafers W horizontally in the circumferential direction. A plurality of plates 31 and, in this example, 150 holding plates 31 are stacked in a shelf shape, and are provided with support columns 32 extending in the vertical direction that support the holding plates 31 at a plurality of locations from the outer peripheral side. In this wafer boat 11, the distance between the holding plates 31 and 31 adjacent to each other (distance between the upper surface of one holding plate 31 and the lower surface of the holding plate 31 facing the upper side of the one holding plate 31). For example, k is 8 mm.

  In this example, five struts 32 are arranged at equal intervals, and each strut 32 does not jump out of the outer edge of the holding plate 31 (on the inner tube 12b side) as shown in FIG. Is arranged. Specifically, the outer peripheral portion of each holding plate 31 is formed with a plurality of, for example, five concave portions 35 that are recessed toward the center of the holding plate 31 so that the support columns 32 are accommodated. Each support column 32 is welded to the holding plate 31 in a state where it is accommodated in the recess 35 of each holding plate 31 over the height direction. That is, each support column 32 supports the holding plate 31 by penetrating the periphery of the holding plate 31. Then, the separation dimension t between the outer edge of each holding plate 31 and the inner wall of the inner tube 12b is narrower than the interval dimension k of the holding plates 31 and 31 described above, as shown in FIG. For example, it is 5 mm. 2 and 3, reference numeral 36 denotes a column portion that supports the holding plates 31 so as to penetrate the central portion of each holding plate 31. Further, as shown in FIG. 1, disc-shaped top plate 37 and bottom plate 38 are provided at the upper end and lower end of wafer boat 11, respectively, but these top plate 37 and bottom plate 38 are omitted in FIG. 3. Then, a part of the wafer boat 11 is enlarged and drawn.

  The substrate placement regions 33 on which the wafers W are placed on the respective holding plates 31 are arranged such that the outer peripheral portion of the wafer W on the outer edge side of the holding plate 31 is positioned on the outer edge of the holding plate 31. Therefore, the outer edge of the wafer W when viewed in the radial direction of the reaction tube 12 and the outer peripheral surface of the support column 32 are aligned on the outline of the holding plate 31. Each substrate placement region 33 is arranged such that the height position of the surface of the wafer W placed on the substrate placement region 33 is the same height position as the surface of the holding plate 31, that is, The upper surface and the upper surface of the holding plate 31 are formed to be flush with each other. Specifically, according to the thickness dimension (for example, 0.5 mm to 2 mm) of the wafer W accommodated in the substrate placement region 33, the surface of the substrate placement region 33 and the lower surface of the holding plate 31 facing the surface. The dimension between is set to 8 to 10 mm, for example. In order to transfer the wafer W between each holding plate 31 and the external transfer arm 60 schematically shown in FIG. 3, the holding plate 31 holds more than the central portion of each substrate placement region 33 and the central portion. A cutout portion 34 is formed by cutting out a region on the outer peripheral side of the plate 31. Accordingly, in each substrate placement region 33, the periphery of the wafer W is supported from below. In FIG. 1, the position of the wafer W is schematically shown. In FIG. 2, the outline of one wafer W is indicated by a broken line in order to draw the notch 34.

  When the wafer W is placed on the wafer boat 11, the transfer arm 60 that supports the wafer W is cut from the upper side of the substrate placement region 33 while the wafer boat 11 is lowered below the reaction tube 12. When the wafer W is lowered so as to pass downward through the notch 34, the wafer W is placed on the substrate placement region 33. Further, the wafer boat 11 is rotated around the vertical axis so that another substrate placement area 33 faces the transfer arm 60 side, and the wafer W is placed on the substrate placement area 33 in the same manner. After the wafer boat 11 is intermittently rotated in this manner to place the five wafers W on the holding plate 31, the transfer arm 60 is lowered, for example, in the same manner with respect to the holding plate 31 below the holding plate 31. Five wafers W are placed. When the wafer W is taken out from the wafer boat 11, the wafer boat 11 and the transfer arm 60 are driven in the reverse order to the case where the wafer W is placed on the wafer boat 11. Note that the transfer arm 60 may be stacked in multiple stages, and a plurality of wafers W may be collectively delivered to the wafer boat 11.

  The gas injector 51 described above is made of, for example, quartz, and is disposed along the length direction of the wafer boat 11. On the side wall of the gas injector 51, gas discharge ports 52 are formed at a plurality of locations in the vertical direction so as to face the wafer boat 11 side. These gas discharge ports 52 are arranged so as to correspond to the respective height positions of the wafers W accommodated in the wafer boat 11, that is, one holding plate 31 is opposed to the upper side of the one holding plate 31. It arrange | positions between each other holding | maintenance board 31 to do. One end of the gas injector 51 is inserted into the inner pipe 12 b from the side wall of the flange portion 17 described above, and the other end is connected to a gas storage source 55 in which processing gas is stored via a valve 53 and a flow rate adjustment unit 54. Has been. As shown in FIG. 2, a plurality of gas injectors 51, for example, four are provided side by side as shown in FIG. 2, and reference numerals “51a”, “51b”, “51c”, and “51d” are assigned to these four gas injectors 51, respectively. Are attached to these gas injectors 51a to 51d, TMA (trimethylaluminum) gas as the first processing gas, O3 (ozone) gas as the second processing gas, and TEMAHf (tetrakis) as the third processing gas. Ethylmethylaminohafnium) and N2 (nitrogen) gas storage sources 54a to 54d, which are purge gases, are connected to each other. The gas discharge port 52 of each gas injector 51 faces the exhaust port 16, but when the support column 32 may affect the uniformity of the film thickness, specifically, do not face the exhaust port 16. May face a position slightly separated from the exhaust port 16 in the horizontal direction.

  This vertical heat treatment apparatus is provided with a control unit (not shown) composed of a computer for controlling the operation of the entire apparatus, and a program for performing a film forming process to be described later is stored in the memory of the control unit. Stored. This program is installed in the control unit from a storage unit which is a storage medium such as a hard disk, a compact disk, a magneto-optical disk, a memory card, and a flexible disk.

  Next, the operation of the above embodiment will be described. First, the wafer boat 11 is lowered to the lower side of the reaction tube 12, and the five wafers W are loaded on the respective holding plates 31 by the transfer arm 60 while rotating the wafer boat 11 intermittently as described above. Put. Then, for example, the wafer boat 11 on which 750 (5 × 150) wafers W are placed is inserted into the reaction tube 12, and the lower surface of the flange portion 17 and the upper surface of the lid body 25 are brought into airtight contact. Next, the atmosphere in the reaction tube 12 is evacuated by the vacuum pump 24, and the wafer W on the wafer boat 11 is adjusted to, for example, about 300 ° C. by the heater 13 while rotating the wafer boat 11 around the vertical axis. Heat. Subsequently, TMA gas is supplied from the gas injector 51 a into the reaction tube 12 while adjusting the pressure in the reaction tube 12 to the processing pressure by the pressure adjusting unit 23.

  At this time, the gas discharge port 52 is located on the side of each wafer W, and the holding plate 31, rather than the region between the outer edge of the holding plate 31 of the wafer boat 11 and the inner wall of the inner tube 12 b, The region between 31 is wider. Therefore, as shown in FIG. 4, the TMA gas supplied into the reaction tube 12 is a holding plate that is wider than the narrow region between the outer edge of the holding plate 31 of the wafer boat 11 and the inner wall of the inner tube 12b. Try to flow through the region between 31 and 31. That is, it can be said that the TMA gas discharged from each gas discharge port 52 is regulated to be diffused upward and downward by the holding plates 31 and 31 as shown in FIG. Therefore, the TMA gas flows toward the exhaust port 16 through the upper side of the wafer W in a laminar state. When the TMA gas comes into contact with the wafer W in this way, the atomic layer or molecular layer of the TMA gas is adsorbed on the surface of the wafer W. Then, the TMA gas that has not been adsorbed on the wafer W is discharged to the outside of the reaction tube 12 through the exhaust ports 16 and 21.

  Next, the supply of TMA gas is stopped, and as shown in FIG. 6, N 2 gas is supplied into the reaction tube 12 to replace the atmosphere in the reaction tube 12. Subsequently, the supply of N2 gas is stopped, and O3 gas is supplied into the reaction tube 12 as shown in FIG. Similarly, this O3 gas flows in a laminar state from each of the gas discharge ports 52 toward the wafer W, oxidizes the components of the TMA gas adsorbed on each wafer W, and produces a reaction made of alumina (Al2O3). Produce things. After the supply of O3 gas is stopped, the atmosphere in the reaction tube 12 is replaced with N2 gas. In this way, a supply cycle for supplying TMA gas, N 2 gas, O 3 gas and N 2 gas in this order is performed a plurality of times, thereby laminating the reaction product layers.

  Thereafter, as shown in FIG. 8, the TEMAHf gas is supplied in a laminar flow into the reaction tube 12 in the same manner, and this gas is adsorbed on the surface of the wafer W. Thereafter, N2 gas and O3 gas are supplied in this order to form a reaction product made of hafnium oxide (HfO2) on the surface of the wafer W. And the supply cycle which supplies these gas in order is performed in multiple times, the reaction product of hafnium oxide is laminated | stacked, and a thin film is formed. Thereafter, the inside of the reaction tube 12 is returned to the air atmosphere, and then the wafer boat 11 is lowered and the wafer W is taken out by the transfer arm 60.

  According to the above-described embodiment, the vertical type in which the processing gas is discharged from the gas discharge port 52 formed at the height corresponding to each wafer W to each wafer W held on the wafer boat 11 to perform the heat treatment. In the heat treatment apparatus, a plurality of circular holding plates 31 are stacked, a plurality of wafers W are held on each holding plate 31, and a column 32 that supports the peripheral portions of the plurality of holding plates 31 is formed from the outer edge of the holding plate 31. It is configured not to jump out. Therefore, since the gap between the holding plate 31 and the reaction tube 12 can be narrowed, the amount of the processing gas that does not contribute to the processing and passes outside the holding plate 31 can be suppressed. For this reason, the processing gas can be effectively used, in other words, the processing gas can be efficiently supplied to the surface of the wafer W. Further, since the thin film can be formed quickly by effectively using the processing gas, productivity can be improved. Furthermore, since a sufficient amount of processing gas is supplied to each wafer W, a thin film having a uniform film thickness can be obtained within the surface of the wafer W, and recesses such as grooves and holes can be formed on the surface of the wafer W. Even if formed, since the processing gas is distributed in the recess, a thin film with high coverage (coverability) can be obtained without supplying a large amount of processing gas. Further, the holding plate 31 supports the periphery of the wafer W, and unlike the plate-like holding plate, the film can be formed on the back surface of the wafer W, so that the wafer W warps in the plate thickness direction (vertical direction). Can be suppressed.

  Since a plurality of wafers W are arranged on each holding plate 31, the footprint of the apparatus required for one wafer W can be suppressed as compared with the case where one wafer W is arranged on the holding plate 31. Therefore, the cost of the apparatus can be reduced. In other words, when the number of wafers W loaded on each holding plate 31 is five, the processing capacity of the apparatus is five times that of a conventional apparatus in which slots containing a single wafer W are stacked in a shelf shape. However, the footprint of the apparatus (the outer diameter of the reaction tube 12) can be about three times. Therefore, for example, even if the height of the vertical heat treatment apparatus (wafer boat 11) is limited by the ceiling surface of the clean room, the number of wafers W that can be processed by the vertical heat treatment apparatus can be increased. The cost of the apparatus required for processing the wafer W can be reduced. In other words, the present invention can increase the number of wafers W that can be processed at one time to several times that of the conventional apparatus. In this example, since five wafers W each having a diameter of 100 mm are arranged in the circumferential direction on the holding plate 31, a general apparatus for 300 mm wafers (reaction tube 12 and heating furnace body 14) is used. The process conditions and apparatus operating conditions established for the 300 mm size wafer W can be used as they are.

  In this way, in order to effectively use the processing gas, the separation dimension t between the outer edge of the holding plate 31 of the wafer boat 11 and the inner wall of the inner tube 12b can rotate the wafer boat 11 in the inner tube 12b. The dimension is as narrow as possible, specifically 3 to 8 mm, preferably 5 to 8 mm. Therefore, the outer part of the support column 32 when viewed in the radial direction of the reaction tube 12 may be located closer to the inner side than the outer edge of the holding plate 31, or the support column 32 protrudes from the outer edge of the holding plate 31. However, the dimensions are very small and are within the scope of the claims as long as the effects of the present invention can be obtained. Specifically, the support column 32 may be closer to the inner side than the position protruding 3 mm outward from the outer edge of the holding plate 31.

  In the above example, five wafers W are placed on each holding plate 31, but three wafers W may be placed as shown in FIG. In this case, the processing capacity of the apparatus is three times that of a conventional apparatus in which slots containing a single wafer W are stacked in a shelf shape, but the footprint of the apparatus is only about 2.2 times. Therefore, the cost of the apparatus can be reduced as in the above example. Further, the number of wafers W placed on the holding plate 31 may be two or more. Even when two wafers W are placed on the holding plate 31, the processing gas can be effectively used in the same manner as in the above-described example.

  Further, as described above, a wafer W having a normal outer diameter of 300 mm may be used in addition to the 100 mm size as described above. Furthermore, for example, even in the case of a rectangular wafer W made of polycrystalline silicon for solar cells, by forming a substrate placement region 33 corresponding to the outer shape of the wafer W on the holding plate 31, Since a laminar gas flow can be formed between 31, uniform processing can be performed without depending on the outer shape of the wafer W, the processing gas can be used effectively, and the cost of the apparatus can be reduced. FIG. 10 shows an example in which a plurality of, for example, three such rectangular wafers W are mounted on the holding plate 31.

  In the example described above, a thin film is formed by using an ALD (Atomic Layer Deposition) method in which an atomic layer or molecular layer processing gas is adsorbed on the surface of the wafer W, and then this processing gas is oxidized to form a reaction product. However, a thin film may be formed by a CVD (Chemical Vapor Deposition) method. In this case, for example, the aforementioned TMA gas and O3 are supplied into the reaction tube 12 at the same time.

Further, the vertical heat treatment apparatus of the present invention is applied to a film forming method for forming a thin film on the surface of the wafer W. For example, O2 gas or H2O gas is supplied as a processing gas, and Si (silicon) on the surface of the wafer W is supplied. The present invention may be applied when performing a thermal oxidation treatment.
Further, the gas discharge port 52 described above may be formed in a slit shape along the length direction of the wafer boat 11. In addition, although the reaction tube 12 has a double tube structure, a duct-like gas supply unit and an exhaust unit that extend in the length direction of the wafer boat 11 are arranged on the outside of the reaction tube 12 in an airtight manner. The gas discharge ports 52 and the exhaust ports 16 may be formed at a plurality of locations on the side surface of the reaction tube 12 in the vertical direction so as to communicate with the respective portions and the exhaust portion. 11 and 12 show the main part of such a configuration example. 11 and 12, 80 is an exhaust duct, and 81 is a gas supply unit. In FIG. 12, the exhaust duct 80 is partially cut away to show the internal exhaust port 16.

  Furthermore, when the wafer W is transferred to the wafer boat 11, the notches 34 are respectively formed in the holding plate 31, but through holes are formed in, for example, three places for each substrate placement region 33, and the elevator can be raised and lowered. A transfer mechanism (not shown) having three pins configured as described above may be provided on the lower side of the wafer boat 11. In this case, for example, when the wafer boat 11 is positioned below the reaction tube 12 and the wafer W is transferred to the upper side of the substrate placement region 33 by the transfer arm 60, the wafer boat 11 is moved from the lower side of the wafer boat 11. Three pins rise through the through holes of the plurality of holding plates 31 and receive the wafer W from the transfer arm 60. Then, when the transfer arm 60 is retracted and the pins are lowered, the wafer W is placed on the substrate placement region 33. Thereafter, the wafers W are sequentially placed on the lower holding plate 31. When taking out the wafers W from the wafer boat 11, the wafers W on the lower side of the wafer boat 11 are sequentially transferred to the transfer arm 60.

  In the example described above, after laminating a reaction product made of alumina and a reaction product made of hafnium oxide on the surface of the wafer W, if necessary, these reaction products are laminated to form a thin film having a laminated structure. You may do it. For example, a sapphire substrate having an outer diameter of 100 mm is used as the wafer W, a GaN (gallium nitride) film is formed on the wafer W by MO-CVD (Metal Organic Chemical Vapor Deposition), and an LED (Light Emitting) is formed. The present invention may be applied to a process for manufacturing a diode device.

  Further, in each of the examples described above, a plurality of wafers W are placed on the holding plate 31, but as shown in FIG. 13, one wafer W may be placed on the holding plate 31. Specifically, the substrate placement region 33 of the holding plate 31 is formed to be concentric with the wafer W, and the outer edge portion of the holding plate 31 extends to the inner tube 12b side from the outer peripheral portion of the wafer W. The separation dimension t between the outer edge of the holding plate 31 and the inner wall of the inner tube 12b is set to be shorter than the separation dimension k between the holding plates 31 and 31 adjacent to each other, as in the example described above. Is done. Each column 32 is arranged so that the wafer W can be carried in and out of the holding plate 31. Even in this case, since the processing gas tends to flow through the region between the holding plates 31 and 31 rather than the gap region between the holding plate 31 and the inner tube 12b, the processing gas can be effectively used. In FIG. 13, the outer tube 12a is not shown.

W Wafer 11 Wafer boat 12 Reaction tube 12a Outer tube 12b Inner tube 21 Exhaust port 31 Holding plate 32 Support column 33 Placement area 52 Gas discharge port

Claims (2)

In a vertical heat treatment apparatus for carrying a heat treatment on a substrate by carrying a substrate holder holding a plurality of substrates in a shelf shape into a vertical reaction tube in which a heating unit is arranged around the substrate holder,
A process gas provided along a length direction of the reaction tube and having a gas discharge port formed at a height corresponding to each substrate in order to supply a process gas to each substrate held by the substrate holder A supply section;
An exhaust port formed at a position opposite to the gas discharge port with respect to the center of the reaction tube,
The substrate holder includes a plurality of circular holding plates each formed with a plurality of substrate placement regions along the circumferential direction of the reaction tube when viewed in a plane, and a peripheral edge of the holding plate A support portion that penetrates the portion and supports each holding plate, and the outer portion of the column when viewed in the radial direction of the reaction tube is at the same position as the outer edge of the holding plate or closer to the inside ,
The distance between the outer edge of the holding plate and the inner wall of the reaction tube is larger than the distance between the upper surface of the substrate supported on the holding plate and the lower surface of the holding plate facing the upper side of the substrate. Is also set short,
Each substrate placement region is formed so that the outer edge of the substrate on the substrate holder and the outline of the holding plate are aligned with each other when viewed in the radial direction of the reaction tube,
Each substrate placement region includes a portion facing the center portion of the substrate placed on each substrate placement region of each holding plate from the back side and a portion on the outer peripheral side of the holding plate as viewed from the portion. A vertical heat treatment apparatus is characterized in that a notch is formed through which a transfer mechanism for transferring the substrate passes.   The outer portion of the support column is located at the same position as the outer edge of the holding plate or at the inner side, and is closer to the inner side than the position protruding 3 mm from the outer edge of the holding plate. Item 2. The vertical heat treatment apparatus according to Item 1.

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