JPH0617281Y2 - Boat support device in vertical heat treatment apparatus for semiconductor article - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boat supporting device in a vertical heat treatment apparatus for semiconductor articles such as a vertical diffusion furnace for diffusing semiconductor wafers.

2. Description of the Related Art Recently, a vertical diffusion furnace has been developed for use in a diffusion process which is one of the manufacturing processes of semiconductor devices such as transistors, ICs and LSIs. This vertical diffusion furnace is arranged so that the longitudinal axis of the heat treatment tube extends substantially vertically, unlike the horizontal diffusion furnace which has been widely used in the past. The semiconductor wafer to be diffused is stored in a predetermined wafer boat and suspended inside the processing tube.

By using such a vertical diffusion furnace, it is possible to prevent the processing tube, which is usually made of quartz, and the quartz boat from coming into contact with each other, so that the generation of quartz particles due to sliding of quartz can be eliminated. Further, automation of the diffusion process can be achieved easily and inexpensively. Furthermore, the use of a vertical diffusion furnace is significant because it saves space, saves energy, and increases the diameter of the wafer to be processed.

A configuration example of such a vertical diffusion furnace will be described with reference to FIGS. 3 and 4.

The illustrated example is a diffusion furnace for diffusing a silicon wafer, and the processing tube 1 made of quartz glass is arranged so that its longitudinal axis extends in a substantially vertical direction. Processing tube 1
The upper part is open as shown in the drawing, and the processing gas introducing port 2 is provided at the bottom part thereof. The processing tube 1 is surrounded by a housing 3 of an electric furnace. Electric furnace housing 3
Is provided with a heater 4 around the processing tube 1 and near the peripheral side surface of the processing tube 1.

The silicon wafer 5 to be processed is housed in the wafer boat 6 and suspended in the processing tube 1. At this time, each silicon wafer 5 is supported in a state of being inclined at a predetermined angle (for example, about 10 °) with respect to the horizontal plane.

The wafer boat 6 is entirely made of quartz glass, and a hook portion 10 is provided on the upper portion thereof. This hook 1
0 is configured to be detachably engaged with a connecting shaft 9 made of quartz glass connected to the lower end of the rotating shaft 11.
The rotating shaft 11 is rotatably supported by a horizontal beam 12, and is rotationally driven by a motor (not shown) via a belt transmission mechanism arranged in the horizontal beam 12. Then, by rotating the wafer boat 6 during the heat treatment of the silicon wafer 5, heating by the heater 4 and contact of the processing gas flow with the silicon wafer 5 are performed as evenly as possible.

The lateral beam 12 is configured to be vertically driven by a vertical driving mechanism (not shown). Then, by the vertical movement of the horizontal beam 12, the wafer boat 6 suspended from the rotating shaft 11 is taken in and out of the processing tube 1.

The rotating shaft 11 and the connecting shaft 9 are connected to each other by a shaft coupling 13. The shaft coupling 13 is composed of two semi-cylindrical members 1
3a and 13b, these members 13a,
13b are connected to each other by four bolts and nuts. As shown in FIG. 4, the connecting shaft 9
The upper part of the is formed into the small diameter portion 14. On the other hand, shaft coupling 1
3, a shaft hole 16 for receiving the small diameter portion 14 of the connecting shaft 9 is provided between the members 13a and 13b. The small diameter portion 14 inserted into the shaft hole 16 has a through hole 22 provided in the shaft coupling 13 and a through hole 23 provided in the small diameter portion 14.
Are connected to each other by bolts 24 that pass through. The shaft joint 13 and the rotary shaft 11 are coupled to each other by fitting a plurality of abutment screws 18 into a groove 19 provided on the outer peripheral surface of the rotary shaft 11.

An upper lid 20 is arranged in the upper opening of the processing tube 1. The upper lid 20 is entirely made of quartz glass, and has a shaft hole for inserting the connecting shaft 9 in the center thereof. The shaft hole has an inner diameter larger than that of the connecting shaft 9, and a gap is formed between the shaft hole and the connecting shaft 9. Then, the processing gas introduced from the inlet 2 provided at the bottom of the processing tube 1 rises inside the processing tube 1 and then leaves a gap formed between the shaft hole of the upper lid 20 and the connecting shaft 9. Exhausted through. The processing gas thus discharged from the processing tube 1 is sucked and collected by an exhaust duct (not shown) arranged so as to cover the entire apparatus.

A locking plate 21 is fixed to the lower side of the upper lid 20 of the connecting shaft 9. Then, when the rotating shaft 11 and the connecting shaft 9 are raised to remove the wafer boat 6 from the processing tube 1, the locking plate 21 fixed to the connecting shaft 9 comes into contact with the lower end surface of the upper lid 20. Then, as the rotating shaft 11 and the connecting shaft 9 rise, the upper lid 20 is lifted, the upper portion of the processing tube 1 is opened, and the wafer boat 6 is taken out.

Problems to be Solved by the Invention In the vertical diffusion furnace of the former conventional example, the silicon wafer 5,
The total weight of the wafer boat 6 and the connecting shaft 9 is supported by the through hole 23 and the bolt 24 provided in the small diameter portion 14 of the connecting shaft 9. However, the connecting shaft 9 of this type is wholly formed of quartz glass, and its mechanical strength is weak, so that it deteriorates over time due to repeated use and heating, and the through hole 23 is particularly weak. It may crack and break. Generally, the connecting shaft 9
Has a service life of at least 6 months, and in order to remove stains due to processing gas, etc.,
Every two to three weeks, the connecting shaft 9 is removed, washed, and maintenance is performed.

However, during this cleaning and maintenance inspection, a small crack cannot be found, the connecting shaft may be damaged during use, and the wafer boat may drop, thereby damaging the wafer boat 6 and the silicon wafer 5, or There is a problem that the processing tube 1 is also damaged during the processing, and the damage becomes extremely large.

Means for Solving the Problems As a concrete means for solving the problems of the above-mentioned conventional example, the present invention provides a semiconductor tube and a processing tube arranged such that a longitudinal axis thereof extends substantially vertically. Wafer boat to be loaded,
In the vertical heat treatment apparatus for semiconductor articles, each of which is provided with a support shaft for suspending the wafer boat at a predetermined position inside the processing tube, and a connecting means for connecting the wafer boat to the support shaft, The means has at least two upper and lower stages of first and second engaging portions for supporting the weight of the wafer boat, and the first engaging portion normally supports the wafer boat, A boat support device, characterized in that the wafer boat is temporarily supported by the second engaging portion when the first engaging portion is damaged. Even if the first engaging portion is damaged, the second engaging portion can prevent the wafer boat from falling, and the second engaging portion also has a predetermined service life like the first engaging portion. But use up to its useful life Rather, it is the sufficient to support the next cleaning and servicing. Therefore, it is possible to substantially prevent the wafer boat from dropping due to breakage of the support shaft during use.

Embodiment An embodiment in which the present invention is applied to a boat supporting device for a vertical diffusion furnace for silicon wafers will be described below with reference to FIGS. 1 and 2.

In the present embodiment, the same parts as those of the conventional one shown in FIGS. 3 and 4 are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 1 and FIG. 2, in the connecting shaft 9 of the present embodiment, the two small flanges 3 are provided in the small diameter portion 30 on the upper part thereof.
1, 32 are formed on the upper and lower sides, respectively. The lower surfaces of these flanges 31 and 32 form first and second supported surfaces, respectively. The connecting shafts 29 are all integrally formed of quartz glass.

On the other hand, a shaft coupling 33 formed of two semi-cylindrical metal members 33a and 33b is provided with a shaft hole 34 for receiving the small diameter member 30 of the connecting shaft 29. Inside the shaft hole 34, two annular recesses 35 and 36 for receiving the two flanges 31 and 32 of the connecting shaft 29 are provided at the top and bottom, respectively. The step portions 39 and 40 of these annular recesses 35 and 36 respectively form first and second supporting surfaces for supporting the first and second supported surfaces, which are the lower surfaces of the flanges 31 and 32, respectively. ing.

Both members 33a and 33b of the shaft coupling 33 are four bolts 3
7 and nut 38 are connected to each other. Further, the shaft coupling 33 and the metal rotary shaft 11 are connected by a plurality of contact screws as in the conventional case.

As shown in FIG. 1, the weight of the wafer boat 6 and the like is usually the first supported surface composed of the lower surface of the flange 31 at the upper end of the connecting shaft 29 and the stepped portion 3 of the recess 35 on the upper side of the shaft coupling 33.
The first support surface 9 is supported by contacting and engaging with each other. At this time, the lower flange 3
Second supported surface composed of the lower surface of step 2 and the step 40 of the recess 36
The second support surface composed of is not engaged with each other in a non-contact state, and is separated from the second support surface by a predetermined gap so as not to support the weight of the wafer boat 6 and the like. The size of the gap provided between the second supported surface, which is the lower surface of the lower flange 32, and the second supported surface, which is the step portion 40, is the weight supported by the connecting shaft 29, that is, the flange 32. The magnitude of the impact on the flange 32 due to the collision between the second supported surface composed of the lower surface of the and the second supported surface composed of the step portion 40,
It is determined in consideration of the thermal expansion of the material forming the connecting shaft 29. For example, when supporting a weight of 10 kg, it is about 0.5 to 1 m.
It is preferably about m.

In this state, stress concentrates on the intersection between the upper flange 31 and the small diameter portion 30, that is, the root portion of the flange 31, so that this root portion is most easily broken. Therefore,
If the base portion of the upper flange 31 is cracked by fatigue, or if the gap between the upper flange 31 and the small diameter portion 30 is cracked by fatigue, the flange 31 and the step portion 39 are broken.
The support of the connecting shaft 29 due to the engagement with
9 drops a little, but this time, the second supported surface composed of the lower surface of the lower flange 32 and the second supported surface composed of the step portion 40 of the recess 36 are brought into contact with each other to engage with each other. The connecting shaft 29 is supported.

As described above, in this example, the first engaging portion formed by the flange 31 and the step portion 39 and the second engaging portion formed by the flange 32 and the step portion 40 are provided to support the weight of the wafer boat 6 and the like. When the first engaging portion is broken, the second engaging portion immediately supports the weight of the wafer boat 6 and the like, so that the wafer boat 6 drops and the silicon wafer and the processing tube 1 are dropped. No accidents that would damage the Since the second engaging portion also has the same strength as the first engaging portion, the second engaging portion can withstand use for 6 months or more, but 2-3 weeks. During each cleaning and inspection, the damage of the first engaging portion can be confirmed. At that time, the connecting shaft 29 may be replaced with a new one.

In the above embodiment, two engaging portions are provided by the two flanges 31 and 32 and the step portions 39 and 40. However, for example, three or more flanges are formed to provide three or more engaging portions. May be. The connecting shaft may be fixed to the wafer boat or integrally formed with the wafer boat. Further, in the above embodiment, the wafer boat 6 is hung on the rotating shaft 11 and rotated.
If it is not necessary to rotate the wafer boat 6, it may be suspended on a support shaft that does not rotate.

In the above embodiment, the flanges 31 and 32 provided on the connecting shaft 29 and the step portions 39 and 40 provided on the shaft coupling 33 constitute the first and second engaging portions. Alternatively, at least two pins may be used, and these pins may be inserted into at least two through holes provided in the connecting shaft to form the first and second engaging portions.

Although the embodiments in which the present invention is applied to a boat supporting device in a silicon wafer diffusion furnace have been described above, the present invention is not limited to the diffusion furnace, and various vertical types for performing oxidation treatment, CVD treatment, etc. of semiconductor articles. It can be applied to a boat support device in a heat treatment device.

Effects of the Invention As described above, in the boat supporting apparatus according to the present invention, the processing tube is arranged such that the longitudinal axis extends substantially vertically, the wafer boat for loading the semiconductor articles, A vertical heat treatment apparatus for a semiconductor article, comprising: a supporting shaft for suspending a wafer boat at a predetermined position inside the processing tube; and a connecting means for connecting the wafer boat to the supporting shaft. To support the weight of the wafer boat, at least two upper and lower first stages
And a second engaging portion, and the wafer boat is normally supported by the first engaging portion, and when the first engaging portion is broken, the second engaging portion causes the wafer boat to be damaged. Since the wafer boat is configured to be temporarily supported, the support shaft that suspends the wafer boat cannot be used until the expected time period in which the service life is expected. Even if it is damaged, it is suspended and supported by the second engaging portion, so that the support shaft and the wafer boat do not drop, and therefore the expensive wafer boat and the semiconductor article are not damaged, and during the heat treatment. In this case, the fall is prevented, and there is no accident such as damage to an expensive processing tube, and it is possible to prevent a great damage due to an accident that has occurred in the past.

Further, since the support shaft is used until the first engaging portion is damaged, even if there is variation, the service life of the support shaft is almost completed, and it is economically excellent.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a main part of a boat supporting apparatus according to an embodiment of the present invention, and FIG. 2 is an exploded front view of the same. FIG. 3 is a schematic vertical sectional view of a conventional vertical diffusion furnace, and FIG. 4 is an enlarged vertical sectional view of a joint portion of the same. In the reference numerals used in the drawings, 1 ... Processing tube 6 ... Wafer boat 11 ... Rotating shaft 29 ... Connecting shaft 31, 32 ... Flange 33 ... Shaft coupling (suspension member) 39, 40. It is a stepped portion (first and second supporting surfaces).

Claims (1)

[Scope of utility model registration request] 1. A processing tube having a longitudinal axis extending substantially vertically, a wafer boat for loading semiconductor articles, and the wafer boat suspended at a predetermined position inside the processing tube. In a vertical heat treatment apparatus for a semiconductor article, each of which has a supporting shaft to hold and a connecting means for connecting the wafer boat to the supporting shaft, in order for the connecting means to support the weight of the wafer boat, at least It has upper and lower two stages of first and second engaging portions, and normally, the wafer boat is supported by the first engaging portion, and when the first engaging portion is damaged, 2. A boat support device, wherein the wafer boat is temporarily supported by two engaging portions.