JPH0752722B2 - Vertical heat treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a vertical heat treatment apparatus.

(Prior Art) In recent years, as a heat treatment apparatus used in a thermal diffusion process or a film forming process in a semiconductor device manufacturing process, space saving, energy saving, a large diameter semiconductor wafer to be processed, and automation A vertical heat treatment apparatus has been developed because it is easy to handle.

In such a vertical heat treatment apparatus, a cylindrical reaction container made of quartz or the like and a reaction furnace main body composed of a heater, a heat equalizing tube, a heat insulating material, etc. provided so as to surround the reaction container are arranged substantially vertically. In this reaction container, a wafer boat made of quartz or the like in which a large number of semiconductor wafers are stacked and accommodated at predetermined intervals is arranged. This wafer boat is mounted on a cylindrical heat-retaining cylinder inserted in the lower part of the reaction container, and the wafer boat is loaded from below inside the reaction container integrally with this heat-retaining cylinder by a vertically movable transfer mechanism. -It is configured to be unloaded.

The heat insulation cylinder is a sealing member for sealing the reaction container, such as an O-ring, which is arranged in a manifold portion that constitutes the lower part of the reaction container, or a magnetic seal for mounting the heat insulation cylinder and rotating the heat insulation cylinder while maintaining airtightness. It protects equipment such as units from high temperatures and keeps the temperature atmosphere in the reaction vessel warm.In general, a cylindrical container filled with a heat insulating member such as quartz glass wool or a ring-shaped flange is provided. There is known a structure in which a large number of layers are arranged at a pitch.

(Problems to be Solved by the Invention) However, the heat retaining cylinder in the conventional vertical heat treatment apparatus described above has the following problems.

In the heat insulation cylinder with a structure using a heat insulating member, the temperature of the lower end of the reaction vessel falls too much, and the reaction gas such as NH ₃ gas and SiH ₂ C
There is a problem that NH ₄ Cl particles are formed by reacting with the l ₂ gas and become NH ₄ Cl particles, resulting in a decrease in yield.

Further, in the heat retaining tube having a structure in which a large number of ring-shaped flanges are arranged in a stack at a predetermined pitch, although it is possible to prevent the temperature of the lower end portion of the reaction vessel from dropping too much, the heat retaining tube has a hole through the central axis of the heat retaining tube. There is a problem in that the radiant heat reaches the magnetic seal unit arranged in the lower part of the heat insulating cylinder and raises the temperature of the magnetic seal unit. In general, the structure of a magnetic seal unit is a structure in which a magnetic fluid is enclosed in a gap between a shaft made of a magnetic material and a rotating body made of a cylindrical permanent magnet that is circumferentially provided with a gap in the shaft. ,
This magnetic fluid is a base oil, such as a fluorine-based base oil, in which magnetic powder, such as iron powder, is dispersed, and the magnetic fluid is kept airtight by the action of the magnetic flux circuit between the shaft and the rotating body. It is configured to transmit movement. Therefore, when the magnetic seal unit is exposed to a high temperature environment, the magnetic fluid and the base oil are volatilized, and the airtightness of the reaction container cannot be maintained.

The present invention has been made to solve the above-mentioned conventional problems, and prevents the temperature of the lower end of the reaction vessel from dropping too much, and also prevents the temperature rise of the magnetic seal unit disposed in the lower portion of the heat insulating cylinder. It is an object of the present invention to provide a vertical heat treatment apparatus provided with a heat retaining cylinder that can be used.

[Structure of the Invention] (Means for Solving the Problems) A vertical heat treatment apparatus of the present invention is a reaction vessel arranged substantially vertically, and an object to be treated which is stacked and arranged in the reaction vessel at a predetermined pitch. In a vertical heat treatment apparatus equipped with a group and a heat retaining tube inserted in the lower portion of the reaction vessel to keep the reaction vessel at a predetermined processing temperature, the heat retaining tube is provided with radiant heat from the side of the heat retaining tube. A cylindrical body for shielding, a plurality of flange portions provided on the outer wall of the cylindrical body at a predetermined pitch along the axial direction for shielding radiant heat from the upper surface of the heat retaining cylinder, and closing the inside of the cylindrical body. It is characterized by comprising a tubular body closing member for shielding radiant heat that has entered the inside of the tubular body.

(Operation) In the vertical heat treatment apparatus of the present invention, a heat insulating cylinder is provided with a cylindrical body for shielding radiant heat from the side surface of the heat insulating cylinder, and a plurality of heat insulating cylinders are provided on the outer wall of the cylindrical body at a predetermined pitch along the axial direction. A flange part for shielding radiant heat from the upper surface of the heat insulation cylinder,
Since it is composed of a tubular body closing member for closing the inside of the tubular body and shielding the radiant heat that has entered the inside of the tubular body, it is possible to prevent the temperature of the lower end of the reaction vessel from dropping too much, and it is arranged at the lower part of the heat insulating tube. It is possible to prevent the temperature rise of equipment such as magnetic seal units.

(Example) An example in which the present invention is applied to a vertical heat treatment apparatus for forming a nitride film will be described below with reference to the drawings.

The reaction container 1 is, for example, an outer cylinder 2 made of quartz and having an inner diameter of 240 mm.
And an inner cylinder 3 having an inner diameter of 200 mm and made of, for example, quartz and housed concentrically in the outer cylinder 2 has a double tube structure. A resistance heater 4 and a heat insulating material 5 are sequentially coated on the outside so as to surround the reaction container 1.

The lower end portion of the reaction vessel 1 has a disc-shaped flange 6 made of stainless steel or the like, and an airtight member, not shown, such as O.
It is hermetically sealed via a ring, and on the flange 6 sideways maintain a predetermined gap with the inner cylinder 3 so as to set the object to be treated in an optimal temperature atmosphere and to insulate the heat in the reaction vessel 1. The heat insulation cylinder 7 is inserted. The heat insulation cylinder 7 is configured as shown in FIG. That is, the heat-insulating cylinder main body inserted in the heat-insulating cylinder 7 is composed of a heat-resistant member such as quartz, and a plurality of, for example, three heat-resistant members having an outer diameter of about 165 mm on the outer periphery of a cylindrical tubular body 8 having an outer diameter of, for example, about 90 mm. For example, ring-shaped flanges 9a, 9b, 9c made of quartz are fixed from the upper end of the cylindrical body 8 by welding or the like at a predetermined pitch, for example, 60 mm pitch,
The lowermost end of the tubular body 8 is closed by a closing member that closes the inside of the tubular body 8, for example, a disk-shaped flange 10 having the same diameter and the same diameter as the above flange, and the lower surface of the flange 10 has the same diameter and the same member as the above tubular body 8. The cylindrical body 11 is projected by a predetermined amount, for example, about 60 mm. The heat insulation cylinder main body is housed in a cylindrical heat insulation cylinder cover 12 made of a heat-resistant member, for example, quartz.
Is configured. A wafer boat 14 made of, for example, quartz in which a large number of semiconductor wafers 13 are arranged at intervals and stacked and accommodated, for example, at a predetermined pitch is mounted on the heat retaining cylinder 7. The wafer boat 14, the heat retaining cylinder 7, Flange 6
Is configured so as to be integrally loaded / unloaded in the reaction vessel 1 by an elevator mechanism (not shown) such as a boat elevator.

A magnetic seal unit 15 is provided at the center of the flange 6 for mounting the heat insulating cylinder 7 and rotating the heat insulating cylinder 7 while keeping the reaction container 1 airtight.

An L-shaped source gas introduction pipe is provided on the outer peripheral wall of the lower end of the reaction vessel 1.
A plurality of, for example three, 16 gas discharge parts are provided so as to project into the inner cylinder 3, and in this embodiment, reaction gas such as three is provided.
SiH ₂ Cl ₂ gas inlet tube for introducing SiH ₂ Cl ₂ gas, NH ₃
NH ₃ gas introduction pipes for introducing gas, and gas mixing introduction pipes for individually introducing SiH ₂ Cl ₂ gas and NH ₃ gas and mixing and discharging them in the gas distribution process are provided on the same plane. ing. Also, after the treatment is completed, the reaction container 1
An N ₂ gas introduction pipe 17 for introducing an inert gas, for example, N ₂ gas, is provided with its gas discharge portion inserted in the gap between the inner cylinder 3 and the outer cylinder 2.

The processing gas introduced into the reaction vessel 1 through each of the source gas introduction pipes 16 is discharged through an exhaust pipe 18 to a vacuum pump (not shown).

In the operation of the vertical heat treatment apparatus having such a configuration, first, the wafer boat 14 accommodating the semiconductor wafer group 13 is inserted into the inner cylinder 3 by the boat elevator (not shown) together with the heat insulation cylinder 7, and then the inside of the reaction vessel 1 is inserted. The specified vacuum degree, for example 0.17 Torr
NH ₃ gas and SiH ₂ Cl ₂ gas are introduced from the respective source gas introduction pipes 16 while being kept at 1, and the semiconductor wafer group 13 is heated by the heater mechanism 4 to a predetermined processing temperature, for example, 700 to 850 ° C. The film forming process is performed. At this time, the temperature control is performed so that the entire reaction container 1, that is, the entire semiconductor wafer group 13 has a constant temperature.

Since the processing gas during processing is discharged from both above and below the semiconductor wafer group 13, the gas concentration in the reaction vessel 1 becomes uniform, and the uniformity between the semiconductor wafers 13 and the individual semiconductor wafers 13 is excellent. It is possible to form a film.

By the way, according to the heat insulating cylinder 7 of the present embodiment, the temperature of the lowermost end of the heat insulating cylinder 7 during processing, that is, the upper end of the magnetic seal unit 15 can be suppressed to about 80 to 100 ° C. or lower.

This is, of course, because the constituent member of the heat insulating cylinder 7 is a quartz member having an excellent heat insulating property, so that heat transfer due to the heat transfer action from the reaction vessel 1 side can be prevented. 8 and a plurality of flanges 9 provided on the outer circumference of the cylindrical body 8
Because it can prevent heat radiation from a, 9b, and 9c.

Particularly, the radiant heat shielding function described below will be described below with reference to FIG.

First, the radiant heat from the reaction container 1 side, that is, the radiant heat a that enters from a substantially vertical direction is due to the respective flanges 9a, 9b and 9c, and the radiant heat b that has entered the inside of the cylindrical body 8 is a disc-shaped flange.
Shield with 10.

On the other hand, the radiant heat b in the lateral direction reflected by the lower surface of the lower inner wall of the inner cylinder 3 is shielded by the flanges 9a, 9b, 9c and the cylindrical body 3.

Further, in this embodiment, the surface of the quartz member constituting the heat insulating cylinder body is formed into a rough surface by plasting or the like to reduce the radiant heat transmittance.

Generally, the solvent of the magnetic fluid enclosed in the magnetic seal unit 15, for example, fluorinated oil or the like, starts to volatilize at about 100 ° C. However, according to the heat insulating cylinder 7 of the present embodiment, the upper end portion of the magnetic seal unit 15 is Since the temperature can be suppressed to about 80 to 100 ° C. or, if necessary, lower than the temperature, it is possible to prevent airtightness failure due to volatilization of the base oil of the magnetic fluid.
In addition, the temperature around the heat insulating cylinder 7 can be arbitrarily adjusted by changing the number of the flanges 9a, 9b, 9c.

In the temperature range of 80 to 100 ° C., NH ₃ gas and SiH ₂ Cl ₂ gas may react with each other to generate NH ₄ Cl, which causes dust. If the holes are provided above the reaction temperature range, for example, in the temperature range of 300 to 400 ° C., such a problem does not occur.

Thus, after the film formation process is completed, the boat elevator (not shown) is lowered while purging the N ₂ gas introduction pipe 17 into the N ₂ gas reaction container 1, and the wafer boat 14 is taken out of the reaction container 1. The film forming work is completed.

[Effects of the Invention] As described above, according to the vertical heat treatment apparatus of the present invention, the temperature of the lower end of the reaction container is prevented from dropping too much, and an apparatus such as a magnetic seal unit disposed below the heat retaining cylinder is provided. It is possible to prevent the temperature rise of equipment.

[Brief description of drawings]

FIG. 1 is an enlarged vertical cross section showing a lower portion of a vertical heat treatment apparatus for explaining an embodiment of the apparatus of the present invention, and FIG. 2 is a cross section and a partial plan view showing the heat retaining cylinder body of FIG. 1 ... Reaction container, 2 ... Outer cylinder, 3 ... Inner cylinder, 4 ... Heater mechanism, 7 ... Heat retaining cylinder, 8 ... Inner cylinder, 9 ... Flange,
10 ... Disk flange, 12 ... Heat insulation cylinder cover, 13 ... Semiconductor wafer group, 14 ... Wafer boat, 15 ... Magnetic seal unit, 16 ... Source gas introduction pipe, 17 ... N ₂ gas introduction tube.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shinji Miyazaki, No. 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Inside the Toshiba Research Institute Co., Ltd. (72) Inventor Takahiko Moriya Komukai-Toshiba, Kawasaki-shi, Kanagawa No. 1 Incorporated company Toshiba Research Institute

Claims (1)

[Claims] 1. A reaction container arranged substantially vertically, a group of objects to be processed which are stacked and arranged at a predetermined pitch in the reaction container, and a predetermined inside of the reaction container inserted into the lower part of the reaction container. In a vertical heat treatment apparatus having a heat retaining cylinder for retaining heat at the processing temperature, the heat retaining cylinder is a cylinder for shielding radiant heat from a side surface of the heat retaining cylinder, and an outer wall of the cylinder along the axial direction. A plurality of flange portions provided at a predetermined pitch for shielding radiant heat from the upper surface of the heat insulating cylinder; A vertical heat treatment apparatus comprising: