JPS6079714A - Diffusion furnace - Google Patents

Abstract

PURPOSE:To improve durability of a furnace core tube by providing a cap integrally with an operating jig which brings a diffusion boat in and out and making the diffusion boat sit by vertical and parallel movement. CONSTITUTION:An operating jig 11 proceeds into a furnace core tube 2 without contact with the inner surface of the tube 2 housing a diffusion boat 9 wherein a wafer is placed in a housing portion 12 of the boat 9. When the diffusion boat 9 arrives at a definite position A, a cap 13 comes in contact with the opening 4 of a furnace and closes the opening 4. Then, a sitting means 15 make the operating jig 11 sit on the inner surface of the tube 2 in a state of holding the operating jig 11 horizontally and a diffusion process is carried out. The inner surface of the furnace core tube 2 is not damaged by the movement of the diffusion boat 9. The weight of the diffusion boat 9 is supported by the sitting means 15 and deformation by fatigue of the furnace core tube can also be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention is a diffusion furnace used to form an oxide film on a wafer made of silicon or the like, or to perform impurity diffusion, annealing, etc. This invention relates to a diffusion furnace that makes a soft landing in a certain position.

Generally, this type of diffusion furnace uses an operating jig to move the diffusion boat in and out of the quartz core tube.
In the past, the diffusion boat itself was slid while remaining in contact with the inner surface of the reactor core tube, so minute foreign matter was generated under the contact between the two, and the foreign matter adhered to the wafers on the diffusion boat. There are disadvantages in that it adversely affects the diffusion process, or scratches occur on the inner wall of the core tube due to the sliding movement of the diffusion boat, shortening the service life of the core tube. Attempts were made to reduce the friction with the inner wall of the reactor core tube by installing multiple rotating wheels on the bottom of the diffusion bow, but no fundamental solution could be found in this case either.

However, as a drastic solution to the shortcomings listed in
The soft landing method described above has been proposed. FIGS. 1(a) to 1(c) show an example of a conventional soft land ink type diffusion furnace. In this case, as shown in FIG. When the diffusion boat 9 is inserted into the reactor core tube 2 to a predetermined position A by the boat loader 14 without contacting the inner surface of the tube 2,
As shown in FIG. 1(b), by the seating means 15 incorporated in the operating jig 11, the tip side of the diffusion boat 9 is first seated, and then the entire diffusion boat 9 is seated on the inner surface of the reactor core tube 2. It looks like this.

However, even in this case, there is a risk that the inner surface of the core tube 2 may be damaged by the tip corner of the diffusion boat 9, and as shown in FIG. Since the reactor port 4 must be closed with a cap (not shown) and the operating jig 11 is detached from the diffusion boat 9 and exits to the outside of the reactor core tube 2, the diffusion boat 9, which has a considerable weight, and the load mounted thereon are required. A considerable load is placed on the furnace core tube 2 due to the large number of wafers 1o placed there, and this causes the problem of early fatigue deformation of the furnace core tube 2.

This invention was made to solve the above-mentioned conventional problems all at once.The purpose of this invention is to eliminate the influence on the wafer due to contact between the diffusion boat and the inner surface of the reactor core tube, and also to eliminate the influence of the inner surface of the reactor core tube itself. The objective is to increase the service life as much as possible, and to fully automate the operation of inserting and removing the wafer into the reactor core tube by integrating the cap with the operating jig.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

In FIGS. 2 to 4, 1 is a furnace body of a diffusion furnace, and 2 is a furnace core tube that passes through the furnace body 1. 3 is a heater arranged near the outer periphery of the furnace core tube 2.

The furnace core tube 2 is made of quartz and is a cylindrical tube having a furnace opening 4 at one end and closed at the other end by a back wall 5.
Gas containing impurities is supplied into the tube 2 from a gas supply port 6 formed in the outer peripheral wall 7 (( A diffusion boat 9 is placed at a predetermined position #A of the furnace port 4.The opening edge of the furnace mouth 4 is formed to have a sufficient flat surface of 1 degree.The diffusion boat 9 holds a large number of wafers 10 at a predetermined interval. It is installed and placed in a predetermined position A inside the furnace core tube 2 and outside the furnace core tube 2 by the operation jig 11.

As shown in FIG. 3, the operating jig 11 has a semi-cylindrical shape in which the upper half of the tip of a long cylindrical quartz tube is cut out, and the diffusion boat 9 is housed and placed in the lower half. A cap 13 is inseparably fixed to the longitudinally intermediate portion of the reactor port 4 to form a boat accommodating portion 12. It enters and leaves the pipe 2. The cap 13 is formed into a square plate shape, and the furnace (closed surface 13
A is formed with high precision in accordance with the planar accuracy of the opening edge of the furnace 1 and 4, and is set to a dimension that allows the opening of the furnace 4 to be completely continuous.

The operation jig 11, with the diffusion boat 9 carrying the wafer 10 placed thereon in its boat housing section 12, is moved into the reactor core tube 2 by the forward movement of the boat loader 14 without coming into contact with the inner surface of the tube 2. However, when the diffusion boat 9 is located at the predetermined position A, the boat 9 must be seated at the lower part of the inner surface of the reactor core tube 2.

This seating means 15 is a traveling guide 16 of the boat loader 14.
It is installed on the lower surface of the cylinder 17 and moves the traveling guide 16, the boat loader 14, and the operating jig 11 up and down.
is connected to the lower surface of the traveling guide 16.

In this case, as shown in FIG. 2, the operating jig 11 advances straight into the reactor core tube 2 due to the forward movement of the boat loader 14, and the cap 13 comes into close contact with the reactor port 4 to close the reactor port 4. Then, the diffusion boat 9 will be positioned above the hollow at the predetermined position it A mentioned above. At this time, a signal is transmitted from the detection means (not shown) to the seating means 15, and all the grungers 18 of the means 16 begin to slowly descend at a constant speed, keeping the operating jig 11 in a horizontal position as shown in FIG. It is seated on the inner surface of the furnace core tube 2, and its lowering operation is stopped.

When the operating jig 11 is seated, the jig 11, the boat loader 14, and the traveling guide 16 are all supported by the seating means 15 at the seating height position, and the diffusion process of the wafer 10 is completed. Again, the champion 11.14.16 is seated in the core tube 2 by the seating means 15.
Move upwards into the hollow space. In this way, the jig 11
The diffusion boat 9 placed on the boat accommodating portion 12 is moved vertically and parallelly by the seating means 15 at a predetermined position A so as to soft land on the inner surface of the reactor core tube 2.

In addition to the boat accommodating portion 12 in the above embodiment, the fixing means for attaching the operation jig 11 to the diffusion boat is, for example, an engagement means provided at the tip of the operation jig 11 and a core engagement means at the base end of the diffusion boat 90. Various types of fixing structures are conceivable, such as providing a means that is engaged and fixed to the means.

Further, the seating means 15 is only one example shown in the above embodiment, and there are various designs such as a parallel link mechanism, a parallel rank mechanism, and a mechanism that moves vertically in parallel by the rotation of a screw. Changes are possible.

As explained above, according to the present invention, when the diffusion boat enters and leaves the reactor core tube at a predetermined position, it is possible to completely eliminate the contact between the boat and the inner surface of the reactor core tube. The generation of fine foreign matter is eliminated, and not only can the influence of foreign matter on the wafer diffusion process be eliminated, but also the problem of scratches occurring on the inner surface of the furnace tube can be solved. Furthermore, since the operating jig itself is equipped with a single cap, the operation of loading and unloading the wafer can be fully automated.

Furthermore, we have installed a seating means (=J) that allows the diffusion boat to sit at a predetermined position within the core tube so that it can move up and down in parallel, so unlike the conventional soft landing method, it can be seated and seated without damaging the inner surface of the core tube at all. In addition to being able to take off the floor, the weight of the diffusion boat can be supported by the seating means in the seated position, so the weight of the boat is not borne by the core tube, and therefore fatigue deformation of the core tube is possible. In combination with the above-mentioned effect of not damaging the inside of the reactor core tube, it is possible to significantly increase the service life of the reactor core tube.

[Brief explanation of drawings]

FIGS. 1A to 1C are cross-sectional views sequentially showing the operating process of the main parts of a conventional diffusion furnace. 2 to 4 show an embodiment of the present invention, FIG. 2 is a sectional view of the main part, FIG. 3 is a perspective view of the operating jig, and FIG. 4 is a sectional view of the main part showing the operating state. It is. 2. Furnace tube, 4. Furnace mouth, 9. Diffusion boat, 10.
・Wafer, 11.. Operation jig, 12. Fixing means (boat accommodating part) for some diffusion boats, 13.. Cap, 15
Seating means, A...predetermined position. Applicant: ROHM Co., Ltd. Agent: Kazuhide Okada, patent attorney

Claims (2)

[Claims] (1) A diffusion boat on which wafers are placed, an operating jig for loading and unloading the same, a cap that opens and closes the furnace opening of the reactor core tube, and a seating means for seating and leaving the diffusion boat at a predetermined position within the reactor core tube. In the diffusion furnace, the operating jig has a cap integrally attached to a longitudinally intermediate portion, and a means for attaching and fixing a diffusion boat to a distal end thereof, and the seating means automatically attaches a diffusion boat. 1Ii- to myself
r in the core tube IIl' by moving vertically and parallelly at the fixed position.
1. A diffusion furnace characterized in that the furnace sits on and leaves the bed. (2) Diffusion boat attachment fixing means of the operation jig; The diffusion furnace according to claim 1, wherein the diffusion boat is accommodated and placed at the tip of the jig.