JP2002110575A - Heat treating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shut off outside air turning around from the opening of a furnace tube in a horizontal type heat treating furnace at the time of taking a semiconductor wafer in or from the furnace or heat treating. SOLUTION: The apparatus comprises a horizontal type furnace tube 6 having an opening 11 at one end for inserting/discharging a mother boat having a mounted semiconductor wafer by a drawing rod 3 and a reactive gas inlet hole at the other end. A shutoff plate 4 for preventing outside air turning around from the opening 11 is mounted on a mid portion of the rod 3 in an integrated structure perpendicular to the rod 3. The rod 3 and the plate 4 contain nitrogen gas introducing passages 14 and the plate 4 has nitrogen gas blow holes I5 on the outer side wall for blowing nitrogen gas 8 from the introducing passages 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus for diffusing impurities and forming a thermal oxide film on a wafer in a semiconductor manufacturing process, and more particularly to a horizontal heat treatment apparatus for performing heat treatment by installing a furnace core tube in a lateral direction. .

[0002]

2. Description of the Related Art The structure of a conventional horizontal heat treatment apparatus used in a semiconductor manufacturing process will be described with reference to the drawings.
FIG. 3 is a cross-sectional view showing the structure of a conventional heat treatment apparatus, and shows a horizontal boat loader diffusion furnace having a cooling zone.

[0003] As shown in FIG. 3, a furnace core tube 6 is formed in a cylindrical shape with quartz or the like, and one end is narrowed down to become an introduction hole 10 for a reaction gas 9, and the other end is an opening 11 while the semiconductor wafer 1 is kept open. Is a loading / unloading port of the mother boat 2 on which is loaded.
A heating zone 12 is formed by installing a heater 5 around the reaction gas introduction hole 10 of the furnace core tube 6, and a cooling zone by blowing dry air 13 around the furnace core tube near the opening 11. 7 are provided.

A quartz mother boat 2 on which semiconductor wafers 1 are mounted at equal intervals is moved in and out of a furnace core tube 6 by a drawer rod 3 also made of quartz. A plurality of disk-shaped flanges (shielding plates 4) for preventing outside air from entering through the openings 11 are integrated in the middle of the drawer rod 3, for example, as disclosed in Japanese Utility Model Application Laid-Open No. 61-162444. The outer diameter of the shielding plate 4 is set to be equal to the inner diameter of the furnace core tube 6 with a predetermined gap therebetween.
It is formed in a size that can move.

The operation of diffusing heat into a semiconductor wafer using a heat treatment apparatus having such a structure will be described. First, a carrier gas such as nitrogen gas is introduced from the introduction hole 10, and the inside of the furnace core tube 6 is heated by the heater 5.
After the inside of the furnace core tube 6 is heated to a predetermined temperature, the mother boat 2 on which the semiconductor wafer 1 is
And inserted into the heating zone 12. At this time, the furnace core tube 6
The opening 11 side is substantially closed by the shielding plate 4 except for a gap between the inner wall of the furnace core tube 6.

Next, a reactive gas 9 containing an impurity gas together with a carrier gas is supplied into the furnace core tube 6 through an inlet 10 to diffuse the semiconductor wafer 1. The introduced carrier gas and the reacted gas are discharged out of the furnace core tube 6 through a gap between the outer periphery of the shielding plate 4 and the inner wall of the furnace core tube 6.
After the completion of the diffusion process, the mother boat 2 on which the semiconductor wafer 1 is placed is drawn out of the heating zone 12 into the cooling zone 7 by the draw-out rod 3 and is stopped for a predetermined time.

[0007]

In the conventional heat treatment apparatus described above, when the mother boat is inserted into the furnace core tube, the outside air flows around, and a natural oxide film is formed on the semiconductor wafer, and the film is formed in the subsequent film formation. There is a problem that causes trouble. The shielding plate was provided to reduce the sneakage of outside air, but since there is always a gap between the shielding plate and the inner wall of the furnace core tube, it can be said that it is not only during the insertion of the mother boat but also during the heat treatment It is impossible to completely shut off the outside air.

In addition, when the semiconductor wafer is drawn from the heating zone to the cooling zone after the heat treatment, outside air similarly enters from the gap on the outer periphery of the shielding plate, and an unnecessary oxide film is formed. . Therefore, when cooling the semiconductor wafer, the mother boat is stopped at a position farther from the furnace core tube opening (closer to the heater) to reduce the influence of the circulating air, and the temperature of the heater is lowered. Because of the means of cooling over time, the time required for the heat treatment was prolonged, which hindered productivity.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is intended to reduce the occurrence of product abnormalities by blocking the outside air from flowing into a furnace core tube and to provide a semiconductor device at a position distant from a heater. An object of the present invention is to enable cooling of a wafer and improve productivity by shortening a cooling time.

[0010]

A heat treatment apparatus according to the present invention comprises:
A horizontal furnace core tube having an opening at one end through which a mother boat loaded with semiconductor wafers is loaded and unloaded by a drawer rod and a reaction gas introduction hole at the other end is provided, and outside air flows from the opening into an intermediate portion of the drawer rod. In a heat treatment apparatus in which a shielding plate for preventing the above problem is integrally mounted at right angles to the drawer rod, the drawer rod and the shield plate have a built-in nitrogen gas introduction path.

The nitrogen gas introduction path is radially branched from the mounting position of the shielding plate through the axis of the drawer bar toward the outer periphery of the shielding plate, and is radially branched. The leading end of the nitrogen gas introduction path is connected to a plurality of nitrogen gas blowing holes provided along the outer peripheral portion of the shielding plate, and the nitrogen gas blowing holes are directed toward the opening direction of the furnace core tube. It is characterized by being open.

The nitrogen gas blown out from the nitrogen gas blowout hole is blown in a direction parallel to the inner wall of the furnace core tube, or is blown at a predetermined angle to the inner wall of the furnace core tube. .

[0013]

Next, an embodiment of the heat treatment apparatus of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing the structure of the heat treatment apparatus of the present invention, and shows a horizontal boat loader diffusion furnace having a cooling zone. FIG. 2 is an enlarged view of a portion A in FIG. The same parts as those used in the description of the related art are denoted by the same reference numerals and described.

As shown in FIG. 1, the furnace core tube 6 is formed in a cylindrical shape from quartz or the like, and one end is narrowed down to become an introduction hole 10 for a reaction gas 9, and the other end is an opening 11 while the semiconductor wafer 1 is kept open. Is a loading / unloading port of the mother boat 2 on which is loaded.
Further, a heater 5 is provided around the reaction gas introduction hole 10 of the furnace core tube 6 to form a heating zone 12, and an opening 1 is formed.
A cooling zone 7 by blowing dry air 13 is provided in the vicinity of the furnace core tube closer to one side.

A motherboard 2 made of quartz, on which a plurality of semiconductor wafers 1 are mounted at equal intervals, has a drawer rod 3 also made of quartz.
Is carried out into and out of the furnace core tube 6. A plurality of disk-shaped flanges (shielding plates 4) for preventing outside air from entering during the heat treatment of the semiconductor wafer 1 or when taking in and out of the semiconductor wafer 1 are integrally formed at right angles with the drawer rod 3 in the middle of the drawer rod 3. The outer diameter of the shield plate 4 is formed to a size that allows the drawer bar 3 to move with a predetermined gap between the shield plate 4 and the inner periphery of the furnace core tube 6.

As shown in FIG. 2, the drawer rod 3 and the shield plate 4 have a nitrogen gas introduction path 14 built in. The nitrogen gas supply path 14 passes through the axis of the drawer rod 3 and It is radially branched at the mounting position and is built in from the center of the shielding plate 4 toward the outer periphery.

A plurality of nitrogen gas blowing holes 15 are provided along the outer peripheral portion of the shielding plate 4, and the distal ends of the nitrogen gas introduction paths 14 branched radially are connected to each other. The nitrogen gas outlet 15 is opened toward the opening 11 of the furnace core tube 6.
The nitrogen gas 8 blown out from the
Can be blown out by changing the blowing direction depending on the angle θ between the direction in which the gas flows and the inner wall of the furnace core tube 6.

If necessary, a plurality of the shielding plates 4 may be attached to the drawer rod 3, and by changing the interval between the shielding plates 4 and changing the direction of blowing the nitrogen gas, the wall of the nitrogen gas increases. In addition, the outside air can be further reduced. In the present embodiment, the case of two sheets is shown.

The operation of diffusing heat into a semiconductor wafer using the heat treatment apparatus having such a structure will be described. First, a carrier gas such as nitrogen gas is introduced from the introduction hole 10, and the inside of the furnace core tube 6 is heated by the heater 5.
After the inside of the furnace core tube 6 is heated to a predetermined temperature, the mother boat 2 on which the semiconductor wafer 1 is
And inserted into the heating zone 12. At this time, the furnace core tube 6
Is substantially closed by the shielding plate 4 except for the gap.

A flexible hose (not shown) for introducing a nitrogen gas 8 into the shielding plate 4 is connected to one end of the drawer rod 3, and the introduced nitrogen gas 8 flows through the drawer rod 3. Nitrogen gas introduction path 1 of shielding plate 4 through
4 and is blown out from a nitrogen gas blowout hole 15. This blowing is always performed when the drawer bar 3 is operated.

Next, a reaction gas 9 containing an impurity gas together with a carrier gas is supplied into the furnace core tube 6 through the introduction hole 10, and the semiconductor wafer 1 is subjected to a diffusion process. The introduced carrier gas and the reacted gas are discharged out of the furnace core tube 6 through a gap between the outer periphery of the shielding plate 4 and the inner wall of the furnace core tube 6.
After the completion of the diffusion process, the mother boat 2 on which the semiconductor wafer 1 is placed is drawn out of the heating zone 12 into the cooling zone 7 by the drawer rod 3, and is stopped for a predetermined time.

As described above, the mother boat 2 drawn into the cooling zone 7 is provided with a heater 5 for improving the cooling effect.
Even if it is stopped at a position near the opening 11 of the furnace core tube 6, which is a position far from the
Since the outside air is prevented from flowing into the furnace core tube 6, the oxidation of the semiconductor wafer 1 is prevented and the cooling time is shortened.

[0023]

According to the heat treatment apparatus of the present invention, since nitrogen gas is blown out from the outer peripheral portion of the shield plate provided on the drawer rod, the nitrogen gas flows into the gap formed between the inner wall of the furnace core tube and the outer periphery of the shield plate. The formation of the wall prevents the outside air from flowing around, and can eliminate the formation of an unnecessary oxide film on the semiconductor wafer. In addition, since the mother boat can be stopped at a position close to the furnace core tube opening away from the heater, the influence of the heater is reduced and cooling can be performed in a short time. As described above, according to the present invention, it is possible to completely block the outside air from flowing into the furnace core tube, so that it is possible to prevent the occurrence of product abnormalities, shorten the cooling time, and improve the productivity.

[Brief description of the drawings]

FIG. 1 is a sectional view of a heat treatment apparatus of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is a cross-sectional view of a conventional heat treatment apparatus.

[Explanation of symbols]

 Reference Signs List 1 semiconductor wafer 2 mother boat 3 drawer rod 4 shield plate 5 heater 6 furnace core tube 7 cooling zone 8 nitrogen gas 9 reaction gas 10 introduction hole 11 opening 12 heating zone 13 dry air 14 nitrogen gas introduction path 15 nitrogen gas blowing hole

Claims (6)

[Claims] 1. A horizontal furnace core tube having an opening at one end through which a mother boat loaded with semiconductor wafers is loaded and unloaded by a drawer rod and a reaction gas introduction hole at the other end, and an opening at an intermediate portion of the drawer rod. In a heat treatment apparatus in which a shielding plate for preventing outside air from flowing in from the outside is integrally mounted at a right angle to the drawer bar, the drawer bar and the shield plate have a built-in nitrogen gas introduction path. Heat treatment equipment. 2. The nitrogen gas introduction path is radially branched from a mounting position of the shielding plate toward an outer periphery of the shielding plate through an axis of the drawer rod, and is incorporated therein. The heat treatment apparatus according to the above. 3. A distal end of a nitrogen gas introduction path radially branched from the shield plate and incorporated therein is connected to a plurality of nitrogen gas blowout holes provided along an outer peripheral portion of the shield plate. The heat treatment apparatus according to claim 1, wherein: 4. The heat treatment apparatus according to claim 3, wherein the nitrogen gas blowing hole is opened toward an opening direction of the furnace core tube. 5. The heat treatment apparatus according to claim 3, wherein the nitrogen gas blown out from the nitrogen gas blowout hole is blown out in a direction parallel to an inner wall of the furnace core tube. 6. The heat treatment apparatus according to claim 3, wherein the nitrogen gas blown out from the nitrogen gas blowout hole is blown at a predetermined angle to an inner wall of the furnace core tube.