JP2655461B2 - Vertical heat treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical heat treatment apparatus for heat-treating a wafer as a semiconductor substrate, and more particularly to a vertical heat treatment apparatus having means for preventing contamination of a reaction system due to entrainment of air and suppressing growth of an oxide film on the wafer. The present invention relates to a heat treatment apparatus.

[0002]

2. Description of the Related Art FIG. 3 is a schematic sectional view of a vertical heat treatment apparatus showing an example of the prior art. Conventionally, this type of vertical heat treatment apparatus is provided with a chamber for evacuating and introducing an inert gas before the wafer is stored in the reaction system in order to prevent air from being entrained in the reaction system, and to provide an inert gas. A so-called load lock system in which the reaction system is housed in an atmosphere of an active gas is employed.

That is, as shown in FIG. 3, the vertical heat treatment apparatus includes a chamber 5 which is evacuated by introducing a cassette 7 for accommodating a wafer, a vacuum pump 9 which evacuates the chamber 5, and a chamber A reaction tube 4 made of quartz, which is provided adjacent to the reactor tube 5, a gas piping system for introducing a reaction gas into the reaction tube 4, a heat retaining tube 2 on which a boat 17 for storing wafers arranged in a vertical direction, and a boat A boat elevator for accommodating wafers 17 in the reaction tube 4, a flange separating the reaction tube 4 and the chamber 5 as the boat elevator rises, and a wafer transfer mechanism for transferring wafers between the cassette 7 and the boat 17. And 3.

Next, the operation of this vertical heat treatment apparatus will be described. First, the boat 1 is placed at an upper limit position by a boat elevator in an empty state. At this time, the flange forming a part of the boat elevator partitions the reaction tube 4 from the chamber 5. Next, the cassette 7 containing the wafer is placed at the transfer position by opening and closing the door 6. Next, the vacuum pump 9 is operated to evacuate the chamber 5, and after a predetermined degree of vacuum is obtained, the inside of the chamber 31 is filled with an inert gas by the gas control valve 10. Next, the boat 17 is lowered by the boat elevator, and the wafer is transferred from the cassette 7 to the boat 17 by the wafer transfer mechanism 3 and waits.
The boat elevator is raised again, and the boat 17 is put into the reaction tube 4 and heat-treated. In this way, when the boat 17 containing the wafer is put into the reaction tube 4, contamination of the wafer due to entrainment of the air into the reaction system is prevented.

[0005]

However, the conventional vertical heat treatment apparatus requires a large-scale vacuum chamber for preventing contamination and a vacuum pump for evacuating the chamber, which not only increases the equipment cost but also increases the cost. There is a problem that a place for installation is occupied widely.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems without requiring a large-scale vacuum chamber or a vacuum pump, reducing the installation area and reducing the cost of the wafer by air entrapment at a low cost. An object of the present invention is to provide a vertical heat treatment apparatus capable of preventing contamination.

[0007]

SUMMARY OF THE INVENTION A vertical heat treatment apparatus according to the present invention has a reaction tube in which a heater is disposed on the outer periphery, a boat having a flange for closing an opening of the reaction tube, and a boat for accommodating a semiconductor wafer. A base, a cover that surrounds the boat and is divided into two parts having a circular tubular shape, a cover opening / closing mechanism that exposes or surrounds the boat by moving the covers to each other, Gas supply means for introducing an inert gas, an elevator for vertically moving the boat, and a wafer transfer mechanism for transferring the semiconductor wafers to the boat, when inserting the boat into the reaction tube, Wrapping the boat with the cover, inserting the boat together with the cover while filling the cover with an inert gas with an inert gas. That.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

FIGS. 1A and 1B are schematic sectional views showing a vertical heat treatment apparatus according to an embodiment of the present invention in the order of operation. As shown in FIG. 1, this vertical heat treatment apparatus divides a wrapping board 17 containing a large number of wafers into two covers 11a and 11b made of quartz, and closes the covers 11a and 11b to each other to wrap the boat 17 and An opening / closing mechanism 1 that separates the boat 17 from each other and exposes the boat 17;
And an elevator (not shown) that moves up and down together with the opening / closing mechanism 1. The flange 20 for closing the reaction tube 4 is provided with a gas inlet 18 for introducing an inert gas.

On the other hand, the opening / closing mechanism 1 for opening and closing the covers 11a and 11b includes a movable base 12 attached to one end of the covers 11a and 11b, a guide 13 for moving the movable base 12 in one direction, and a movable base 12 And a frame 16 for holding both ends of the guide 13 and the feed screw 14, and a motor 15 attached to the frame 16 and rotating the feed screw 14.

Although not shown in the drawings, there is provided a wafer transfer mechanism for transferring a wafer by moving a movement arm in a direction perpendicular to the plane of the drawing. Elevating elevators are mounted under the frame 16. The gas inlet is for introducing an inert gas so that the wafer is not oxidized, and filling the sealed cover with an inert gas having a pressure higher than the atmospheric pressure. Next, the operation of inserting a wafer into the reaction tube of this vertical heat treatment apparatus will be described. First, FIG.
As shown in (a), when the boat 17 is at the lowest point in the elevator, the empty boat 17 is moved by the wafer transfer mechanism.
Transfer the wafer to be processed. Next, the cover 11a and 11b are moved in the direction of the arrow by the rotation of the motor 15 of the opening / closing mechanism 1, and the boat 17 is wrapped with the cover 11a and 11b as shown by a two-dot chain line. Next, the inert gas inlet 1
An inert gas is introduced into the covers 11a and 11b through 8 to replace the air with the inert gas. After a certain period of time, the elevator is raised in this state, and the boat 17 is inserted into the reaction tube 4 as shown in FIG. At this time, a large amount of inert gas is also introduced from the reaction gas inlet 19.
As a result, the space formed by the reaction tube 4 and the covers 11a and 11b inserts the boat 17 while releasing the inert gas from the gap, thereby preventing the atmosphere from getting into the reaction tube 4. Next, the reaction gas inlet 19
More reactive gas is introduced, the wafer is heated by the heater 7, and heat treatment is performed.

After the processing, the wafer is taken out in the reverse order of the above description. The boat 17 is wrapped and held by the covers 11a and 11b until the wafer is sufficiently cooled, and the inert gas is kept flowing to keep the wafer. To prevent oxidation of the wafer by air.

FIGS. 2A and 2B are a perspective view and a partial sectional view of a cover portion showing a cover opening / closing mechanism according to another embodiment of the present invention. In the vertical heat treatment apparatus according to this embodiment, a cover opening / closing mechanism for shutting off air in the atmosphere is divided into two quartz tubes having different diameters as shown in FIG. Covers 11e and 11d,
This is to expose the inside by overlapping and rotating each other. That is, about one third of the circumference of each quartz tube is cut out.

The opening and closing mechanism for opening and closing the covers 11a and 11d is, as shown in FIG.
0a, the cover 11d is mounted on the flange 20a via a ball 25 on the outside of the cover 11d and the protective plate 21 for fixing the cover 11d to the flange 20a.
, A pinion 23 meshing with the ring gear 24, and a motor 22 for rotating the pinion 23.

The operation of this vertical heat treatment apparatus differs from the above-described embodiment only in the operation of opening and closing the cover, and the other operations are the same. That is, when the wafers are transferred to the boat, the covers 11c and 11d are moved by the rotation of the motor 22 as shown in FIG.
An opening is formed as shown in FIG. The wafer is stored in the boat through the opening by the wafer transfer mechanism. Then, when the wafer is transferred to the boat, the inert gas is covered 11
c and 11d.

This embodiment has an advantage that the cover opening / closing mechanism can be made smaller than the above-described embodiment.

[0017]

As described above, the present invention provides a half-cylindrical quartz cover for enclosing a boat for storing wafers in the atmosphere, and means for filling the cover with an inert gas. By providing a cover opening / closing mechanism that moves the two covers to each other and exposes or wraps the boat on which the wafer is mounted, it is possible to insert the boat into the reaction tube without entraining air in the gas reaction tube. Since it is possible, there is no need for a large-scale vacuum chamber or vacuum pump, and there is an effect that a smaller and less expensive vertical heat treatment apparatus can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an operation order of a vertical heat treatment apparatus according to an embodiment of the present invention.

FIGS. 2A and 2B show an opening and closing mechanism in a vertical heat treatment apparatus according to another embodiment of the present invention, wherein FIG. 2A is a perspective view of a cover portion, and FIG.

FIG. 3 is a schematic cross-sectional view of a vertical heat treatment apparatus showing an example of the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Opening-and-closing mechanism 2 Insulating cylinder 3 Wafer transfer mechanism 4 Reaction tube 5 Chamber 6 Door 7 Cassette 8, 15, 22 Motor 9 Vacuum pump 10 Valve 11a, 11b, 11c, 11d Cover 12 Movable table 13 Guide 14 Feed screw 16 Frame 17 Boat 18 gas inlet 19 reaction gas inlet 20, 20a flange 21 protective plate 23 pinion 24 ring gear 25 ball

Claims (3)

(57) [Claims] A reaction tube in which a heater is arranged around the outside;
A boat table having a flange for closing the opening of the reaction tube and mounting a boat for storing semiconductor wafers, a cover surrounding the boat and divided into two circular tubes, and moving the covers together. A cover opening / closing mechanism for exposing or enclosing the boat, gas supply means for introducing an inert gas into the cover, an elevator for vertically moving the boat, and transferring the semiconductor wafer to the boat. A wafer transfer mechanism, and when inserting the boat into the reaction tube, wrap the boat with the cover, and insert the boat with the cover while filling the cover with an inert gas with an inert gas. A vertical heat treatment apparatus. 2. The apparatus according to claim 1, wherein the cover opening / closing mechanism includes a movable base attached to one end of the cover, and a drive mechanism that linearly moves the movable base to open and close the cover. The vertical heat treatment apparatus according to claim 1. 3. The cover opening / closing mechanism is formed by changing the outer diameter of the cover, has a structure capable of rotating with respect to the center of the boat, and includes a rotating mechanism for rotating the cover. The vertical heat treatment apparatus according to claim 1.