JP5341370B2 - Vertical furnace equipment - Google Patents

Description

  The present invention relates to a vertical furnace apparatus in which a plurality of silicon substrates and glass substrates are arranged in multiple stages along a vertical direction to perform heat treatment.

  The semiconductor manufacturing process includes a heat treatment for heating a substrate such as a silicon substrate or a glass substrate at a high temperature. As an apparatus for performing heat treatment on a substrate, a vertical furnace apparatus that stores a plurality of substrates arranged in multiple stages along a vertical direction is used. The vertical furnace apparatus includes a process tube for storing a plurality of substrates in a predetermined processing atmosphere.

  The process tube has a cylindrical shape with an open bottom surface, and a plurality of substrates are carried into and out from the bottom surface. During the heat treatment, the bottom surface of the process tube is closed by the floor. The floor is provided below the process tube so as to be movable up and down, and a plurality of substrates are placed on a boat installed on the upper surface.

At the lower end surface of the process tube, a flange portion is formed over the entire circumference in order to enlarge the contact area with the upper surface of the floor and maintain the hermeticity in the process tube by the floor (see, for example, Patent Document 1). .
JP 2007-299795 A

  However, the lower end portion of the process tube is cooled during the heat treatment in order to prevent deterioration of peripheral devices and a high working environment. For this reason, for example, in a heat treatment using a gas containing a component that aggregates at a low temperature such as water vapor, such as pyrogenic oxidation treatment, the gas introduced into the process tube during the heat treatment is the lower end of the process tube. Condensation on the inner peripheral surface and the upper surface of the floor. For example, in a conventional vertical furnace that performs steam oxidation, moisture remains between the flange and the floor, and when reactive gas is introduced into the process tube in a later process, it dissolves in the remaining moisture. Or, it may directly aggregate to form a corrosive aqueous solution. As a result, there is a problem that the O-ring and surrounding metal parts are corroded, and further, there is a problem that the working environment is deteriorated.

The object of the present invention is to move condensed liquid such as moisture generated by condensation at the lower end of the process tube to the center of the floor and evaporate it again, so that condensed liquid such as moisture is placed between the flange portion and the floor. It is an object of the present invention to provide a vertical furnace apparatus that can prevent the residual and prevent corrosion of peripheral parts and deterioration of the working environment.

The vertical furnace apparatus according to the present invention includes a process tube and a floor. The process tube has a cylindrical shape with an open lower end surface and a flange portion around the lower end surface. The floor is disposed so as to be movable up and down below the process tube so as to open and close the lower end surface of the process tube, and a first recess is formed. The first recess is an inclined surface that is formed in a range including a portion corresponding to the position of the inner surface of the process tube on the upper surface of the floor, and is inclined downward toward the center side of the process tube. Has an inclined surface located closer to the center of the process tube than the inner surface of the process tube .

  In this configuration, condensed liquid such as moisture generated by condensation on the inner surface of the lower end portion of the process tube falls into the first recess on the floor due to gravity and moves toward the center side of the process tube along the inclined surface. Move. Since the temperature of the upper surface of the floor is higher at the center side of the process tube, condensed liquid such as moisture that has dropped into the first recess evaporates at the center side of the process tube. For this reason, condensed liquids, such as a water | moisture content, do not remain between a flange part and a floor.

  In this configuration, the first recess may be formed within a range including the position of the inner portion of the bottom surface of the flange portion on the top surface of the floor. The contact area between the bottom surface of the flange portion and the top surface of the floor is reduced, and it is possible to more reliably prevent the remaining condensed liquid such as moisture between the flange portion and the floor.

  In addition, a second concave portion located within the range where the bottom surface of the flange portion is located on the upper surface of the floor and outside the first concave portion, and a communication hole communicating from the second concave portion to the outside of the process tube are provided. There may be provided an introducing means for introducing an inert gas into the second recess through the communication hole. By introducing an inert gas from the outside of the first recess, condensed liquid such as moisture generated by condensation between the flange portion and the floor can be reliably moved to the first recess.

  According to the present invention, the condensed liquid such as moisture generated by condensation on the lower end portion of the process tube is moved to the center of the floor and evaporated again, so that the condensed liquid such as moisture is provided between the flange portion and the floor. Residuals can be prevented and corrosion of peripheral devices and deterioration of the working environment can be prevented.

  FIG. 1 is a schematic cross-sectional view of a vertical furnace apparatus according to an embodiment of the present invention. The vertical furnace apparatus 10 includes a process tube 1, a heater 2, a liner tube 3, a floor 4 and a support 5. A substrate loading / unloading portion is formed below the vertical furnace apparatus 10.

  The process tube 1 has, for example, a cylindrical shape with a bottom surface made of quartz. A first flange portion 11 is formed at the lower end of the outer peripheral surface of the process tube 1, and a second flange portion 12 is formed at the lower portion in the vertical direction. A boat in which a plurality of substrates are arranged in multiple stages along the vertical direction is carried into and out of the process tube 1 from the furnace port on the bottom surface.

  Below the process tube 1, a transfer device for loading and unloading a boat on which a substrate is mounted is installed. The first flange portion 11 is cooled by cooling water in order to reduce the temperature of the lower end portion of the process tube 1 in order to prevent a failure of the transfer device and deterioration of the work environment of the substrate loading / unloading operation.

  The heater 2 surrounds the periphery of the process tube 1 except for the lower end with a gap. Therefore, the heater 2 also has a cylindrical shape with an open bottom. The heater 2 is driven so that the internal temperature of the process tube 1 becomes a predetermined processing temperature.

  The liner tube 3 is disposed between the process tube 1 and the heater 2. Accordingly, the liner tube 3 also has a cylindrical shape with an open bottom. The liner tube 3 causes the heat from the heater 2 to uniformly act on the outer surface of the portion excluding the lower end portion of the process tube 1.

  The floor 4 is disposed below the process tube 1 so as to be movable up and down. The substrate is placed on the upper surface of the floor 4 through the boat while the floor 4 is lowered to the lowermost part. With the floor 4 raised to the top, the bottom surface of the first flange portion 11 contacts the top surface of the floor 4.

  An O-ring 13 is disposed between the vicinity of the outer peripheral portion on the bottom surface of the first flange portion 11 and the top surface of the floor 4. The O-ring 13 keeps the airtightness in the process tube 1 in a state where the floor 4 is located at the uppermost part. The reason why the O-ring 13 is disposed in the vicinity of the outer peripheral portion of the first flange portion 11 is to prevent the O-ring 13 from being deteriorated by disposing the O-ring 13 made of an elastic material as low a temperature as possible. .

  The support 5 supports the process tube 1, the heater 2, and the liner tube 3. A hole 51 is formed in the support 5. The process tube 1 passes through the hole 51 from below. The support 5 supports the lower end of the heater 2 and the lower end of the liner tube 3 on the upper surface. The support 5 supports the second flange portion 12 of the process tube 1 on the bottom surface.

  FIG. 2 is a sectional view around the furnace port of the vertical furnace apparatus. FIG. 3 is a plan view of the floor 4. In a range including a portion where the lower end portion of the inner peripheral surface of the process tube 1 is located on the upper surface of the floor 4, a first recess 41 is formed over the entire periphery. The first recess 41 has an inclined surface that descends toward the center of the process tube 1 and has a mortar shape.

  With respect to the radial direction of the process tube 1, the outer end of the first recess 41 is located at an intermediate portion of the bottom surface of the first flange portion 11. Therefore, the bottom surface of the first flange portion 11 is in contact with the top surface of the floor 4 only at a part near the outer edge portion.

A second recess 42 is formed on the entire periphery of the outer surface of the first recess 41 at the portion of the upper surface of the floor 4 that contacts the bottom surface of the first flange portion 11. A communication hole 43 is formed at each of a plurality of positions in the circumferential direction of the second recess 42 on the floor 4. The communication hole 43 communicates the second recess 42 to the outside of the process tube 1 and is connected to the gas source 45 via the introduction pipe 44. The gas source 45 introduces an inert gas such as N ₂ gas into the second recess 42 via the introduction pipe 44 and the communication hole 43.

  A step 46 is formed on the outer edge of the upper surface of the floor 4. The O-ring 13 is stored in the step portion 46.

As an example of the heat treatment in the vertical furnace apparatus 10, a combustion gas of hydrogen gas and oxygen gas is introduced into the process tube 1 to form an oxide film on the surface of the substrate in a water vapor atmosphere, and then a nitrous oxide gas ( There is a steam oxidation treatment in which N ₂ O) is introduced into the process tube 1. In the steam oxidation treatment, water adheres to the inner peripheral surface of the lower end portion of the process tube 1 due to condensation.

  The water adhering to the inner peripheral surface of the lower end portion of the process tube 1 moves toward the center of the process tube 1 along the inclined surface after dropping into the first recess 41 by gravity. On the upper surface of the floor 4 where the first recess 41 is formed, the temperature of the center side of the process tube 1 is higher than that of the outer side in the radial direction adjacent to the second flange portion 12. For this reason, the water moved to the center side of the process tube 1 in the first recess 41 evaporates and does not remain on the floor 4.

  Further, the radially outer end of the first concave portion 41 is located in the middle portion of the first flange portion 11, and the contact area between the upper surface of the floor 4 and the first flange portion 11 is reduced. . For this reason, it is difficult for water generated by condensation to remain in the contact area between the upper surface of the floor 4 and the first flange portion 11.

  Further, an inert gas is introduced from the outside of the process tube 1 into the second recess 42 arranged outside the first recess 41 in the radial direction. For this reason, during the heat treatment, water vapor does not flow radially outward between the upper surface of the floor 4 and the first flange portion 11 beyond the second concave portion 42, and condensation occurs in this portion. There is nothing. Further, even if dew condensation occurs inside the second recess 42 between the upper surface of the floor 4 and the first flange portion 11, the water adhering to this portion passes from the second recess 42 into the process tube 1. Is guided into the first recess 41 by the inert gas directed toward.

  By these, it can prevent more reliably that the water produced by dew condensation remains in the contact range of the upper surface of the floor 4 and the 1st flange part 11. FIG.

  Therefore, even when a reactive gas such as nitrous oxide gas is introduced into the process tube 1, a strong acidic or strong alkaline aqueous solution is not formed, and the metal around the O-ring 13 and the lower end of the process tube 1 is not formed. Does not corrode parts.

  In the above embodiment, the steam oxidation treatment has been described as an example. However, the present invention has the same effect even in a heat treatment using a gas containing a component that aggregates at a low temperature other than the steam oxidation treatment.

  The above description of the embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

It is sectional drawing which shows the outline of the vertical furnace apparatus which concerns on embodiment of this invention. It is sectional drawing around the furnace port of the same vertical furnace apparatus. It is a top view of the floor with which the vertical furnace apparatus is equipped.

Explanation of symbols

1-process tube 2-heater 3-liner tube 4-floor 5-support 10-vertical furnace device 11-first flange portion 12-second flange portion 41-first recess 42-second recess 43-Communication hole 44-Pipe for introduction 45-Gas source 46-Step part

Claims (3)

A cylindrical process tube having a lower end surface opened and a flange portion around the lower end surface;
A floor arranged to be movable up and down below the process tube so as to open and close the lower end surface of the process tube,
The floor is an inclined surface inclined downward toward the center side of the process tube within a range including a portion corresponding to the position of the inner surface of the process tube on the upper surface, and is an end on the center side of the process tube The vertical furnace apparatus provided with the 1st recessed part in which a part has the inclined surface located in the center side of the said process tube rather than the inner surface of the said process tube .   2. The vertical furnace apparatus according to claim 1, wherein the floor includes the first recess within a range including a position of an inner portion of a bottom surface of the flange portion on an upper surface. The floor is within a range where the bottom surface of the flange portion is located on the top surface and is located outside the first recess, and from the second recess to the outside of the process tube. It has a communication hole that communicates,
The vertical furnace apparatus according to claim 1, further comprising an introduction unit that introduces an inert gas into the second recess through the communication hole.

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