JP2502929Y2 - Vertical heat treatment device with heat insulation cylinder - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a vertical heat treatment apparatus having a heat insulation tube, and a large number of minute micro-insulators are provided inside a cylindrical heat insulation table on which a wafer support boat is installed. The present invention relates to a vertical heat treatment device that houses a heat retaining cylinder having a space.

“Prior Art” Conventionally, for example, as shown in FIG. 3, a support boat 3 having semiconductor wafers 4 stacked therein can be housed in a quartz glass furnace core tube 2 surrounding a heating means 1, While the semiconductor wafer 4 mounted on the support boat 3 is heated to a predetermined temperature range by the heating means 1 and controlled, a reaction gas or an inert gas is flown to the surface area of the semiconductor wafer 4 to oxidize the surface area of the semiconductor wafer 4. , A heat treatment apparatus for performing various heat treatments such as diffusion, vapor phase growth, annealing, etc. is known, and in this type of heat treatment apparatus, a vertical structure in which the furnace core tube 2 is erected vertically in order to save the installation area. However, in order to prevent variations in the thickness of the thin film formed or implanted in the surface area of the wafer 4 and in the impurity concentration distribution, the heating zone A in the furnace core tube 2 is used. Furnace core tube 2
A heat insulating cylinder 5 made of quartz glass is arranged between the opening ends to equalize the space temperature for the heat treatment of the wafer 4 and the heating means 1 surrounded by the furnace core tube 2 is positioned above the heat insulating cylinder 5. By making the heat insulating cylinder 5 function as a heat insulating material, high temperature is prevented from propagating to the O-ring 6 and other sealing parts provided on the open end side of the furnace core tube 2.

In such an apparatus, the support boat 4 is placed directly on the upper surface of the heat insulating tube 5, but the heat insulating tube 5 is generally a long fiber quartz glass in a hermetically sealed quartz glass cylinder 5a. Since it is constructed by enclosing the wool 5b, it has poor load-bearing capacity, which limits the number of wafers and the increase in diameter.

Moreover, since the upper surface side of the heat insulating cylinder 5 is always exposed to high temperature by the radiant heat from the heating means 1 surrounded by the furnace core tube 2 above it, the gas (air ) Thermally expands to further increase the pressure load,
5a may be destroyed.

For this reason, the present inventor has previously shown that the heat insulation tube 5 has a large number of minute spaces inside, such as a foam glass body, as shown in FIG. A quartz glass body stretched vertically and horizontally, in other words, a quartz glass plastic body having a large number of minute spaces inside.
The heat insulation cylinder 5'formed by 5c is used, and the heat insulation cylinder 5'is divided into a plurality of small cylinders without placing the support boat 4 directly on the heat insulation cylinder 5'and the divided cylindrical body. Disclosed is a technique in which a cylindrical frame body 7 for integrally housing is prepared, and the support boat 4 is installed via the frame body 7. (Japanese Patent Application No. 62-203499) "Technical problem to be solved by the invention" However, even if the heat insulating tube is housed in the frame body 7, as a result, the heating area on the support boat 4 side and the ventilation state are not maintained. In order to have a structure arranged in the furnace core tube 2, for example, a CV
In a device such as the D device for performing vapor phase growth in a substantially vacuum state, the plastic body 31 is evacuated and then the plastic body 31 is evacuated.
It is preferable to conceal the surface side of the transparent glass layer 32 with a transparent glass layer 32 and to seal under reduced pressure, but it is difficult to evacuate the plastic body existing as closed cells or continuous cells, and the vacuuming is the heat retention. The larger the diameter of the cylinder 5, the more difficult and longer the time. For this reason, in the above-mentioned prior art, the heat retaining cylinder is divided into a plurality of small diameters. However, if such a configuration is adopted, the function (heat retaining power and adiabatic force) of the heat retaining cylinder itself is reduced and the total surface area is large. Therefore, during the vacuum treatment, the gas and particles adsorbed on the surface thereof are ejected, which also causes wafer contamination.

Further, the division into a plurality of heat retaining tubes as described above not only complicates the attachment and removal thereof, but also complicates the structure of the frame body 40 surrounding them.

Further, as described above, the structure in which the heat retaining tube is directly ventilated to the wafer processing area means that the treated gas film adheres to the surface of the heat retaining tube, and in order to remove the film, the heat retaining tube is washed with hydrofluoric acid or the like after the heat treatment. However, there is a case in which the glass layer is etched by the cleaning and the cleaning liquid may get inside the bubbles.

In view of the drawbacks of the prior art, the present invention has a heat insulating property, a heat retaining property and a high pressure resistance that can withstand a large diameter and a large number of sheets, and is particularly suitable for use as a reduced pressure processing apparatus such as CVD. An object is to provide a vertical heat treatment apparatus having a tube.

[Means for Solving Problems] The present invention is a heat insulating base in which a wafer supporting boat 4 is installed on an upper surface and a heat insulating cylinder 50 made of the plastic is housed in a lower space.
The first feature is that the space 40 for storing the heat-insulating cylinder and the space A for storing the wafer support boat are airtightly divided through the heat insulating base 40 by using 40.

The second feature is that the heat insulating cylinder storage space B can be ventilated or depressurized through a contact portion between the base 70 supporting the heat insulating base 40 or the heat insulating base flange portion 41. It is in.

And preferably, the heat insulating cylinder 50 is formed by one heat insulating cylinder 50, and the one heat insulating cylinder 50 and the heat insulating base 40 are respectively arranged concentrically with respect to the furnace core tube 2, and at the upper surface side of the heat insulating cylinder 50. The rear side of the wafer supporting portion of the heat insulating base 40 is configured to be supported.

[Operation] According to the technical means, since the heat insulation cylinder storage space B and the wafer support boat storage space A are airtightly divided through the heat insulation base 40, the heat insulation cylinder storage space B side is maintained in the ventilation state. It is possible to always keep the heat insulation cylinder storage space B under normal pressure,
Accordingly, since it is possible to form the plastic body 31 forming the heat retaining cylinder 50 under normal pressure without evacuation, it is easy to increase the diameter of the heat retaining cylinder 505.

Also, in an apparatus for performing vapor phase growth in a substantially vacuum state such as the CVD apparatus shown in FIG. 4, it is sufficient to reduce the pressure in the storage space B through the ventilation holes of the base, and at this time, the heat insulating cylinder is made of quartz instead of wool. Wool dust is not sucked into the depressurized piping system because it is made of glass plastic.

In other words, this is because the heat insulating cylinder 50 can be formed with one heat insulating body in accordance with the shape of the furnace core tube 2 without dividing the heat insulating cylinder 50, so that it has sufficient heat insulation capacity and heat insulating capacity to cope with the increase in diameter. This is possible, and since the gas such as air is present in the minute bubbles of the heat insulating cylinder 50, the heat insulating function and the heat insulating function are further improved.

Also, one heat insulating cylinder 50 is sufficient, because the shape of the heat insulating base 40 for accommodating the heat insulating cylinder 50 is simplified and the heat insulating cylinder 50 can be easily attached and removed, so that only the heat insulating base 50 to which the film is attached can be washed. Well and easy.

In addition, as mentioned above, when the diameter of the heat insulating base 40 for mounting the support boat 4 in accordance with the furnace core tube 2 is increased, the strength resistance of the heat insulating base 40 is reduced by that amount. Since the heat insulating cylinder 50 and the heat insulating base 40 are arranged concentrically with respect to the furnace core tube 2 respectively because they are formed of a quartz glass plastic body having pressure resistance per se, the heat insulating base is provided on the upper surface side of the heat insulating cylinder 50. 40
By supporting the back side of the wafer support part, the strength resistance does not decrease even when the diameter of the heat insulating base 40 is increased, and thus the number of wafers mounted on the support boat 4 is increased. It can be dealt with in some cases.

[Embodiment] Hereinafter, a preferred embodiment of the present invention will be exemplarily described in detail with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but merely illustrative examples. Nothing more than.

FIG. 1 shows a main part configuration of a heat treatment apparatus having a vertical structure according to an embodiment of the first aspect of the present invention, and illustrates a lower part of a furnace core tube 2 in which a heat insulating cylinder 505 is arranged.

Reference numeral 2 denotes a cylindrical dome-shaped vertical furnace core tube 2 provided with a flange portion 21 at its lower end side opening portion, and the flange portion 21 can be installed on the upper surface of the flange portion 41 on the heat insulating base 40 side, and is airtight. Configure.

The heat insulating base 40 is formed of a transparent quartz glass cylinder having an outer diameter slightly smaller than the inner diameter of the furnace core tube 2, and has a flat upper surface on which the support boat 4 can be mounted and is provided at the lower end opening. The flange portion 41 on the furnace core tube 2 side 21
And the same diameter. A ring body 42 is concentrically provided on the flat upper surface so that the support boat 4 can be positioned and mounted on the ring body 42.

The base 70 has a disk shape having the same diameter as the outer diameter of the flange portion 41, and the base 70 is provided on the lower surface side of the flange portion 41 of the heat insulating base 40.
The peripheral surface can be installed.

Further, the base 70 has a ring body 71 concentrically protrudingly provided on the upper surface side close to the inner wall surface of the heat insulating base 40, and the heat insulating cylinder 50 can be positioned and installed on the ring body 71. Stand
A through hole 72 is formed in the central portion of 70 to allow ventilation to the outside.

As a result, since the heat insulating cylinder storage space B sandwiched between the heat insulating base 40 and the base 70 can be ventilated and the furnace core tube 2 is airtightly installed on the upper surface side of the heat insulating base 40, the furnace core tube The wafer support boat storage space A and the heat insulation cylinder storage space B inside 2 are airtightly divided.

The heat insulating cylinder 50 installed on the base 70 is formed of a plastic body 31 having a large number of minute bubbles inside and a surrounding body 32 made of transparent quartz glass surrounding the plastic body 31.

Next, in order to explain the manufacturing procedure of the plastic body 31, first, a crystalline or vitreous quartz fine powder is put into a quartz crucible 32 having an opening at the upper side and having the same shape as the surrounding body 32 and only a large height. Then, by heating in a vacuum furnace at a temperature of about 1300 to 1600 ° C, a so-called foam glass-like plastic body 31 having a large number of minute spaces inside and a quartz thin film stretched vertically and horizontally is formed. It

At this time, it is preferable that foamed glass-like plastic body 31 having a large number of vacuum microspaces can be formed by heating the quartz fine powder with water mixed with carbon powder in a mud-like state to heat it.

Then, the plastic body 31 formed in this way is heated by the heating, the surface thereof is integrally welded to the quartz crucible 32, and the volume is reduced, so that the upper portion of the reduced crucible is cut, A lid is welded to the upper surface, and the outer periphery of the plastic body 31 is surrounded by a surrounding body 32.

In this embodiment, since the heat insulating cylinder storage space B is airtightly separated from the wafer support boat storage space A, the plastic body 31 taken out from the crucible 32 is kept as it is.
It can also be used as 50, and a thin transparent quartz glass layer may be formed only on the surface layer by rubbing the surface with a burner.

And since the heat insulating cylinder 50 has a pressure resistant strength also for the plastic body itself and has a thick walled enclosure that can also be used as a crucible on its surface, its height is substantially the same as the storage space height. It is preferable that the temperature is set so that the upper surface side of the heat insulating cylinder 50 can support the back surface side of the wafer supporting portion of the heat insulating base 40.

FIG. 4 shows an embodiment applied to a CVD apparatus. To explain mainly the differences from the above-mentioned embodiment, a pressure reducing pipe system 73 is provided in a vent hole 72 of a base 70, a furnace core tube 2, a heat insulating base 40. O-rings 22 and 43 are respectively interposed between the flanges 21 and 41 and the base 70 provided on the lower end side of the wafer storage space A and the heat insulation cylinder storage space B so that decompression or vacuum can be maintained. There is.

At this time, when the storage space B is decompressed through the ventilation holes 72 of the base 70, since the heat retaining cylinder 50 is made of quartz glass plastic rather than wool, wool debris is sucked into the decompression piping system 73 and clogged. There is no.

[Advantage of device] As described above, according to the present invention, as a pressure reducing device for CVD, etc., while sufficiently satisfying the heat insulating property, heat retaining property and high pressure resistance that can withstand the increase in diameter and the number of sheets. It is also possible to provide a vertical heat treatment apparatus having a heat insulation tube that is preferably used.

It has various remarkable effects.

[Brief description of drawings]

FIG. 1 and FIG. 4 are front cross-sectional views of a main part showing the configuration of the main parts of a vertical heat treatment apparatus according to an embodiment of the present invention, and FIGS. 2 and 3 are front cross-section views of a conventionally known heat treatment apparatus. It is a figure. 3: Wafer support boat 31: Quartz glass plastic body, 50: Heat insulation cylinder 40: Heat insulation base, B: Heat insulation cylinder storage space A: Wafer support boat storage space 70: Base, 2: Core tube

Claims (2)

(57) [Scope of utility model registration request] 1. A wafer support boat is installed on an upper surface, and a heat insulating base having a heat insulating cylinder made of a silica glass plastic body having a large number of minute spaces inside is provided in a lower space, and the heat insulating base is provided through the heat insulating base. The heat insulation cylinder storage space and the wafer support boat storage space are airtightly separated, and the heat insulation cylinder storage space is ventilated from below through a base supporting the heat insulation base or a contact portion between the base or the base. Vertical heat treatment equipment characterized by being able to reduce pressure 2. The one heat insulating cylinder and the heat insulating base are arranged concentrically with respect to the furnace core tube, respectively, and the back surface of the wafer supporting portion of the heat insulating base can be supported by the upper surface of the heat insulating cylinder. 1) Vertical heat treatment device