JP5192137B2 - Wafer boat - Google Patents

Description

  The present invention relates to a wafer boat used in a vertical CVD apparatus used in a semiconductor device manufacturing process.

  Semiconductor devices manufactured using silicon include an oxidation process for forming an oxide film on the surface of a silicon substrate (silicon wafer), a diffusion process for introducing impurities such as phosphorus and boron, and a silicon nitride or polycrystalline silicon film. It is manufactured by forming a fine circuit on a silicon substrate by a film forming process by a low pressure CVD (chemical vapor deposition) method to be formed. In these oxidation process, diffusion process, and film formation process, semiconductor manufacturing apparatuses such as an oxidation diffusion apparatus, an annealing apparatus, and a low pressure CVD apparatus are used. In these apparatuses, all include a furnace body part for inserting a plurality of silicon wafers into the furnace and heating the silicon wafer body to a high temperature, a gas introduction part for supplying various gases into the furnace, an exhaust part, etc. A plurality of silicon wafers can be simultaneously processed (batch processing).

  FIG. 7 shows a vertical reduced pressure CVD apparatus as an example. The CVD apparatus shown in FIG. 7 includes a furnace body 701 in which a wafer to be processed is accommodated, a heater (not shown) is disposed on the inner peripheral surface, and the interior of the furnace body 701 is heated to a high temperature so that the high temperature state is maintained. Sustainable. The furnace body 701 is connected to a vacuum pump (not shown) so that the inside of the furnace body 701 can be depressurized to 1.3 kPa or less. A process tube 702 made of high-purity quartz or silicon carbide (SiC) is provided inside the furnace body 701.

  A boat receiver 704 is provided at the center of the base 703 covered with the process tube 702, and a vertical rack-shaped wafer boat 705 made of SiC, quartz or the like is disposed on the boat receiver 704. In the vertical direction of the wafer boat 705, a plurality of silicon wafers 721 for forming a semiconductor device such as a large scale integrated circuit (LSI) are held at a predetermined interval. Further, a gas introduction pipe 706 for introducing a reaction gas into the furnace is disposed on the side of the wafer boat 705, and a thermocouple protection pipe 707 containing a thermocouple for measuring the temperature in the furnace is provided. Is provided.

In the vertical reduced pressure CVD apparatus shown in FIG. 7 configured as described above, a plurality of silicon wafers 721 are placed in a furnace using a wafer boat 705. With the silicon wafer 721 placed in this manner, the inside of the furnace is depressurized to 133 kPa or less, heated to a high temperature of, for example, 800 to 1200 ° C., and SiCl together with a carrier gas such as H ₂ through the gas introduction pipe 706. _By introducing a reactive gas (source gas) such as ₄ into the furnace, a polycrystalline silicon film (polysilicon film) or a silicon oxide film (SiO ₂ ) is formed on the surface of the silicon wafer 721.

  By the way, the wafer boat used in such a vertical vertical reduced pressure CVD apparatus is subjected to non-uniform heating or cooling when being carried into and out of the furnace, and a large thermal stress is generated. Conventionally, several dummy wafers 722 having the same shape as the silicon wafer 721 are arranged on the upper and lower portions of the wafer boat 705 in order to maintain the gas flow and temperature uniformity in the furnace. Yes. In addition, in the vertical direction of the wafer boat 705, a plurality of monitor wafers 723 are provided at predetermined positions in order to check the state of particles adhering to the silicon wafer 721 and the film thickness of the film formed on the silicon wafer 721. The silicon wafer 721 is mixed and disposed.

  In such a vertical vertical reduced pressure CVD apparatus, a wafer boat 705 holding a silicon wafer 721, a dummy wafer 722, and a monitor wafer 723 is used. As this wafer boat, a hollow body structure composed only of a CVD-SiC film (thickness: 300 μm to 1500 μm) has been proposed (see Patent Document 1). According to this wafer boat, because of the structure of only high-purity SiC that does not have a base material, contamination by impurities from the base material can be suppressed. Hereinafter, a wafer boat 705 having a hollow body structure composed only of a CVD-SiC film will be briefly described with reference to FIG.

  A wafer boat 705 shown in FIG. 8 includes a pair of upper flange member 751a and lower flange member 751b having an outer diameter larger than that of a wafer to be accommodated, and a plurality (four in the drawing) of slit rod members 752 connecting them. It is composed integrally with. These have a hollow body structure made of a CVD-SiC film. The upper flange member 751 a is disposed on the upper side of the dummy wafer 722, and the lower flange member 751 b disposed on the lower side is a portion placed on the boat receiver 704. An upper hole 755 is formed at the center of the upper flange member 751a, and a lower hole 756 is formed at the center of the lower flange member 751b. Further, a groove 753 (partially shown in the drawing) for holding each wafer is cut into the inner surface of each slit bar member 752 on the boat.

  Further, the upper flange member 751a and the lower flange member 751b are provided with a notch groove 754 on the other end side with respect to the center portion thereof. The notch groove 754 is cut between the outer peripheral portion and the inner peripheral portion of each flange member 751a, 751b. The notch groove 754 is provided at a position separated from the support position by connecting the upper flange member 751a and the lower flange member 751b by the slit bar member 752.

JP 2002-288537 A Japanese Patent No. 3479201

  However, in the above-described conventional wafer boat having a hollow structure of the CVD-SiC film, the two flanges and the slit bar member connecting the flanges are integrally formed, so that it is substantially impossible to replace each part. It was possible. When such a wafer boat is used, a portion where a problem such as breakage occurs concentrates on a specific part such as a notch groove. Even if a specific part is broken in this way, the above-described conventional wafer boat is replaced as a whole, which places a great burden on the user, including the cost. As described above, the wafer boat having the hollow structure of the CVD-SiC film has characteristics such as no occurrence of contamination from the base material, but has a problem that it is difficult to use in an actual production site.

  On the other hand, there is an assembly-type wafer boat in which an upper flange member and a lower flange member and a slit bar member that connects them are constituted by detachable individual parts (see Patent Document 2). If it is an assembly-type wafer boat, it is possible to replace each part, for example, it is possible to replace only a broken slit bar member. However, in the assembly type wafer boat, the slit bar member does not have a hollow structure. As a matter of course, the groove portion to be the wafer mounting portion is not a hollow structure. This is considered because it is very difficult to make a hollow structure in a state where the strength of the slit bar member serving as the connecting portion is maintained. As described above, the assembly type wafer boat has a structure with a large heat capacity because the slit bar member with which the wafer contacts is not a hollow structure.

  The present invention has been made to solve the above-described problems, and an object thereof is to reduce the heat capacity with an assembly-type wafer boat.

A wafer boat according to the present invention includes a plurality of hollow structures formed with a first base and a second base, a plurality of support columns that detachably connect the first base and the second base, and a groove portion for placing a wafer. A wafer support member, the groove portion is constituted by a protrusion formed on the wafer support member, and the wafer support member is held between the first base and the second base by penetrating the post, and the post and the wafer a hollow portion formed in the gap and projections provided between the inner wall surface of the support member, the post, is formed in a cylindrical shape, the wafer support member, that is formed in a hollow structure of the rectangular cross-sectional It is what I did. Therefore, the heat capacity of the wafer support member with which the wafer to be processed comes into contact is reduced as compared with the case where the wafer structure does not have a hollow structure.

In the wafer boat, U Fine support member may be formed from deposited silicon carbide by chemical vapor deposition.

  As described above, according to the present invention, the first base and the second base of the wafer boat are detachably connected to each other by the support, and the wafer support member is held by the support being penetrated. Therefore, an excellent effect is obtained that the heat capacity can be reduced by an assembly-type wafer boat.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a configuration example of a wafer boat according to an embodiment of the present invention. As shown in FIG. 1, a pair of upper flange member (first base) 101a and lower flange member (second base) 101b having an outer diameter larger than that of each of the wafers, and a plurality of them (in the drawing, shown) 4) struts 102. The wafer boat shown in FIG. 1 includes a wafer support sleeve (wafer support member) 103 having a hollow structure in which a groove 104 for holding a wafer is formed.

  The wafer support sleeve 103 is held between the upper flange member 101a and the lower flange member 101b when the support column 102 is penetrated. Each wafer support sleeve 103 is arranged so that the groove 104 faces the inside of the wafer boat. In other words, the wafer support sleeve 103 is held such that the groove 104 faces the side through which the center line of the upper flange member (first base) 101a and the lower flange member (second base) 101b passes. Note that the normal of the surface on which the groove 104 is formed does not necessarily pass through the center line. Each of these members is made of silicon carbide (SiC), and can be formed from, for example, silicon carbide deposited by chemical vapor deposition.

  In FIG. 1A, some wafer support sleeves 103 are not shown, and some support pillars 102 are shown. In FIG. 1B, the wafer support sleeves 103 are not provided, and the upper flanges are supported by the pillars 102. The state which the member 101a and the lower side flange member 101b were connected is shown. Note that the four flanges 102 connect the upper flange member 101a and the lower flange member 101b. However, the present invention is not limited to this, and the three columns 102 connect the upper flange member 101a and the lower flange member 101b. Alternatively, the upper flange member 101a and the lower flange member 101b may be connected by five or more struts 102. Further, it is not necessary to provide the wafer support sleeve 103 on every support 102. For example, the upper flange member 101 a and the lower flange member 101 b may be connected by five columns 102, and the wafer support sleeve 103 may be provided on three of the columns 102.

  For example, the support column 102 is formed in a cylinder having an outer diameter of 10 mm. In the wafer support sleeve 103, the cross section of the groove 104 is formed in a rectangle of 12 mm × 7 mm, and the cross section of the protrusion for constituting the groove 104 is formed in a rectangle of 12 mm × 12 mm. The interval between the grooves 104 is 8 mm, the width in the arrangement direction of the grooves 104 is 5 mm, and the total length is 1000 mm.

  Further, as shown in the perspective view of FIG. 2A, each support column 102 is fixed to the lower flange member 101 b by a connection screw 204 and a nut 205. The same applies to the upper flange member 101a. The column 102 is provided with a female screw portion 121 at an end portion, and one male screw portion 241 of the connection screw 204 is screwed to each column 102. The other male screw portion 242 of the connecting screw 204 with the male screw portion 241 screwed to the support column 102 passes through a through hole provided in the lower flange member 101b, and is screwed to the nut 205 and tightened. One end (lower end) of the support column 102 is fixed to the lower flange member 101b.

  In addition, a nut accommodating portion 111 formed of a circular recess in which the nut 205 is accommodated is formed in the through hole of the lower flange member 101b. The nut 205 that is screwed into the male threaded portion 242 of the connecting screw 204 is accommodated in the nut accommodating portion 111, so that the lower surface of the lower flange member 101b is in a flat state without protrusions. Further, as shown in the plan view of FIG. 2 (b), the side surface of the nut 205 is composed of opposing parallel flat portions and an outwardly convex curved portion that follows these, and a predetermined jig is used to It is possible to screw and tighten the male screw portion 242 inside the housing portion 111. In some cases, the nut housing portion is not provided.

  As described above, according to the wafer boat illustrated in FIGS. 1 and 2, the upper flange member 101 a and the lower flange member 101 b are detachably connected by the plurality of columns 102. In addition, since the wafer support sleeve 103 is provided separately from the support column 102 that connects the upper flange member 101a and the lower flange member 101b, it is possible to replace the support unit 102 such as the support column 102 and the wafer support sleeve 103. Become. For example, even if one of the wafer support sleeves 103 provided at four locations is damaged, according to the present wafer boat, only the damaged wafer support sleeve 103 needs to be replaced. There is no need to replace it.

  Further, since the upper flange member 101a and the lower flange member 101b are connected not by the wafer support sleeve 103 but by the support column 102, the wafer support sleeve 103 has a strength for supporting (holding) the wafer. That's fine. For this reason, the freedom degree of the shape of the wafer support sleeve 103 can be increased.

  As shown in FIG. 1, an upper hole 151a is formed in the central portion of the upper flange member 101a, and a lower hole 151b is formed in the central portion of the lower flange member 101b. The upper hole 151a and the lower hole 151b are formed in a disk shape having the same shape and a solid structure. The upper hole 151a and the lower hole 151b are preferably circular, oval or barrel-shaped.

  In addition, you may make it provide a notch groove in the other end side rather than these center parts in the upper side flange member 101a and the lower side flange member 101b. This notch groove should just be provided between the outer peripheral part and inner peripheral part of the upper side flange member 101a, for example. The same applies to the lower flange member 101b. Further, the notch groove only needs to be provided at a location separated from the position connected and supported by the column 102. Moreover, the notch groove should just be 1 mm-4 mm in width. By providing the notch grooves, even if there is a temperature difference between the upper flange member 101a and the lower flange member 101b and there is a difference in expansion and contraction in the diametrical direction, each of the notches is extended by the notch grooves. Deflection in the current direction. For this reason, the bending force added to each support | pillar 102 becomes small, and it becomes possible to suppress generation | occurrence | production of the crack of the support | pillar 102 (refer patent document 1).

  Next, connecting a plurality of support columns will be described. As shown in FIGS. 3A and 3B, a plurality of support columns 102 a can be used as longer support columns 102 by connecting them with a connection screw 204.

  When a plurality of wafer support sleeves are connected and used, for example, as shown in FIG. 4, a joint 131a and a joint 132b may be provided on the wafer support sleeve 103a and the wafer support sleeve 103b, and these may be engaged. When a plurality of wafer support sleeves are engaged in this way, if any one wafer support sleeve is fixed so that it cannot be rotated around the internal support column, the other wafer support sleeves can also rotate. It becomes impossible. As a result, the plurality of wafer support sleeves through which one support column penetrates can always face the surface in which each groove is formed in the same direction. In this structure, the wafer support sleeve is not fixed in the extending direction of the support and is not restrained by the support.

  Next, the support column 102 and the wafer support sleeve 103 will be described. As shown in FIG. 5, a gap 501 having a predetermined interval is provided between the support 102 mounted in the wafer support sleeve 103 and the inner wall surface of the wafer support sleeve 103. Thus, by providing the gap 501, the support column 102 can be easily inserted into the wafer support sleeve 103. In addition, since the gap 501 functions as a heat insulating layer, when the wafer boat is heated, the heat capacity of the region where the wafer is supported becomes the heat capacity of the wafer support sleeve 103, and the heat capacity is lowered. Since the heat capacity is proportional to the weight (mass), the wafer support sleeve 103 having a hollow structure is significantly reduced in mass as compared with the wafer support sleeve having a solid structure, and a significant decrease in heat capacity can be expected. In addition, as shown in FIG. 5B, the heat capacity can be further reduced by providing the hollow portion 503 in the portion of the protruding portion 502 constituting the groove 104.

  Next, a method for manufacturing the wafer boat made of silicon carbide will be briefly described. Hereinafter, a case where the wafer support sleeve 103 is formed will be described as an example. First, as shown in FIG. 6A, a base material 601 made of graphite is formed. The base material 601 includes a portion 602 serving as a protrusion for forming a groove. Next, as shown in FIG. 6B, silicon carbide film 611 is formed to a thickness of about 300 to 1500 μm by depositing silicon carbide on the surface of base material 601 by a chemical vapor deposition (CVD) method. Let it be a molded state.

  Once the silicon carbide films 611 are formed in this way, they are heated to, for example, 900 ° C. in an oxygen atmosphere so that the substrate 601 is burned and removed through the opening where the substrate 601 is exposed. As shown in FIG. 6C, a hollow wafer support sleeve 103 is formed. The support column 102, the connecting screw 204, and the nut 205 can also be formed in the same manner as described above. Therefore, the upper flange member 101a and the lower flange member 101b also have a hollow structure. Moreover, the support | pillar 102, the connection screw 204, and the nut 205 form the internal thread part 121 and the external thread part 241 after shape | molding similarly to the above-mentioned. The upper flange member 101a and the lower flange member 101b have a solid structure, but they can be formed in a hollow structure.

  Thus, according to the wafer boat formed only by the silicon carbide film formed by the CVD method, it is possible to prevent contamination of the wafer used for manufacturing the semiconductor device and increase the number of times of use. It can be in a state with high durability. In the above description, the groove 104 is formed on one surface side of the wafer support sleeve 103 having a rectangular cross section, but the present invention is not limited to this. For example, grooves may be formed on the four side surfaces of the wafer support sleeve 103. In this case, the ridge portion formed by the groove only needs to be circular in plan view. In this case, the wafer support sleeve may be formed in a cylinder.

  Further, in the above description, each component of the wafer boat is configured only by the silicon carbide film formed by the CVD method. However, the present invention is not limited to this, for example, it is configured by a sintered body of quartz or silicon carbide. Also good. For example, even if the upper flange member 101a and the lower flange member 101b are made of quartz, and the columns 102 are made of a sintered body of quartz or silicon carbide, they may be made of partially different materials. good. However, as described above, since the hollow structure can be easily formed by the manufacturing method in which silicon carbide is deposited on the surface of the base material by the CVD method, the wafer support sleeve should be formed from silicon carbide deposited by the CVD method. Is preferred. Further, since the wafer to be processed comes into contact with the wafer support sleeve, it is preferable to form the wafer support sleeve from silicon carbide deposited by the CVD method from the viewpoint of contamination.

It is a perspective view which shows the structural example of the wafer boat in embodiment of this invention. It is a perspective view which shows the example of a structure of some wafer boats in embodiment of this invention. It is a block diagram which shows the example of a structure of some wafer boats in embodiment of this invention. It is a perspective view which shows the example of a structure of some wafer boats in embodiment of this invention. It is sectional drawing which shows the example of a structure of some wafer boats in embodiment of this invention. It is process drawing which shows the example of the manufacturing method of the wafer boat in embodiment of this invention. It is a block diagram which shows the structural example of a vertical vacuum CVD apparatus. It is a perspective view which shows the structural example of the conventional wafer boat.

Explanation of symbols

101a ... Upper flange member (first base), 101b ... Lower flange member (second base), 102 ... Column, 103 ... Wafer support sleeve (wafer support member), 104 ... Groove, 111 ... Nut housing part, 121 ... Female thread portion, 204... Connection screw, 205... Nut, 241, 242.

Claims (2)

A first base and a second base;
A plurality of struts detachably connecting the first base and the second base;
A plurality of wafer support members having a hollow structure in which grooves for wafer placement are formed,
The groove is constituted by a protrusion formed on the wafer support member,
The wafer support member is held between the first base and the second base by penetrating the support column,
A gap provided between the support column and the inner wall surface of the wafer support member and a hollow portion formed in the protrusion ,
The strut is formed in a cylindrical shape, the wafer support member, the wafer boat characterized that you have been formed in the hollow structure of the rectangular cross-sectional. In the wafer boat according to claim 1 Symbol placement,
The wafer boat is characterized in that the wafer support member is made of silicon carbide deposited by chemical vapor deposition.

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