JPH0156147B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Prior Art] The present invention relates to a method for cleaning a furnace core tube. For example, a quartz tube used in the manufacture of semiconductor devices is disclosed in Japanese Patent Application Laid-Open No. 143760/1983.

In the production of semiconductor devices, integrated circuits, etc., thin semiconductor plates (wafers) are passed through a heated quartz tube to form a film on the wafer surface or diffuse impurities. . During this work, various products are generated in the reactor core tube (also simply referred to as the tube) due to the reaction of the reaction gases, and these products also adhere to undesirable tube walls other than the wafer. . Therefore, this adhesion layer forms a lump, falls from the tube wall, and adheres to the wafer surface.
This may cause abnormal growth of the film on the wafer surface. In addition, impurities contained in the deposited layer re-evaporate into the tube and diffuse again into the wafer surface layer (so-called autodoping), resulting in non-uniform diffusion concentration.

Therefore, the furnace core tube is removed from the diffusion furnace (heat treatment equipment) every fixed number of times, and cleaning work is performed to remove the coating that adheres to the inner wall of the tube.This cleaning work is performed as shown in Figures 1 and 2. It is proposed to use a cleaning device with a similar structure. That is,
This cleaning device is provided with a first cleaning tank 1 to a third cleaning tank 3 in parallel, and the first cleaning tank 1 is filled with an etching solution such as silicone or In the case of compounds, an etching solution mainly containing hydrochloric acid is placed in the second cleaning tank 2, and pure water is sequentially supplied to the second cleaning tank 2. Further, a plurality of rollers 5 whose rotation is controlled are disposed below the third cleaning tank 3, and the reactor core tube 4 cleaned in the second cleaning tank 2 is placed on these rollers 5 and rotated. There is. In addition, the third cleaning tank 3
An injection pipe 6 for spraying pure water onto the reactor core tube 4 on the rollers 5 is disposed at the upper part of the inner wall of the reactor.

In the case of such a cleaning device, the vicinity of both ends of the core tube 4 are supported by arms 7 bent in an arc shape at the bottom, and the etching solution is immersed in the etching liquid 8 in the first cleaning tank 1 to adhere to the inner wall of the core tube 4. After that, the arm 7 is raised, moved horizontally, and lowered, and the core tube 4 is placed in the cleaning liquid 9 made of pure water in the second cleaning tank 2 to wash away the etching liquid and the like. Furthermore, the arm 7 is moved to place the furnace tube 4 on the roller 5 in the third cleaning tank 3. As shown in FIG. 2, a thin tube section (branch tube) 1 at one end of the furnace tube
A pure water supply pipe 12 is connected through a rotary joint 11 which is rotatable to the main body, and pure water is flowed from the pure water supply pipe 12 into the reactor core tube 4 to clean the inside of the pipe. Further, pure water is sprayed onto the core tube 4 from the upper injection pipe 6 to wash the outer wall of the core tube 4. At this time, since the rollers 5 both rotate in the same direction, the furnace core tube 4 continues to rotate in a constant rotation direction, and the cleaning liquid flows over the entire inner and outer walls of the furnace core tube 4 to perform cleaning.

[Problem that the invention seeks to solve]

However, such a cleaning device and its cleaning method have the following drawbacks.

(1) When cleaning in the third cleaning tank, it is necessary to connect a rotating joint to the reactor core tube each time cleaning is performed, resulting in poor work efficiency.

(2) Since the pure water supply pipe is connected to the reactor core tube through a rotating joint, there is no way that the pure water supply pipe would be twisted by the rotation of the reactor core tube, but in reality, the pure water supply pipe is connected to the rotating joint. Since there is no fixed structure in the vicinity, the pure water supply pipe is twisted, the supply of pure water fluctuates, and the inside of the pipe cannot be sufficiently cleaned.

(3) Since the pure water supply pipe runs along the bottom of the third cleaning tank, there is a risk that the rubbery pure water supply pipe will be corroded by the acid, creating new impurities and contaminating the reactor core tube. .

(4) The branch pipes of the reactor core tube have a structure in which one end of the reactor core tube narrows rapidly, and the cleaning liquid flows from the branch pipe into the large diameter part of the reactor core tube. As a result, a vortex of flow is generated in the constriction region, and the metabolism of the cleaning liquid is extremely slow in this region, making it impossible to sufficiently clean the inner wall of the constriction curved surface of the reactor core tube.

(5) Since there are no large-diameter rotating joints on the market for core tubes without branch pipes, such cleaning equipment cannot clean them. In other words, it has low versatility.

(6) When the reactor core tube is inserted into and removed from the liquid in the first and second cleaning tanks, the structure is such that the reactor core tube is inserted and removed horizontally, so when the reactor core tube is submerged in the liquid, the branch pipe side is blocked. The leakage of the air inside the pipe is also insufficient. Due to the small air bubbles remaining in the tube, some areas are not etched or cleaned, making it impossible to effectively etch and clean. In addition, since the air inside the tube is difficult to leak, the tube may float and the set position may shift, resulting in insufficient support by the arm or the inability to place the tube on the rollers as specified. I feel relaxed.

[Purpose of the invention]

Therefore, an object of the present invention is to eliminate the above-mentioned drawback (6), and to provide a method for cleaning a reactor core tube that allows sufficient cleaning and high work efficiency.

[Means for solving problems]

Means for solving the above problem (6) is that in a method for cleaning a core tube in which the core tube is cleaned by immersing the core tube in a liquid tank containing a liquid, a portion near one end of the core tube is provided. and the vicinity of the other one end are supported by first and second supports, respectively, and the core tube is moved to the vicinity of the liquid level of the liquid tank by the first and second supports, and the By lowering the first support, one end of the reactor core tube is partially immersed in the liquid of the liquid tank, and while maintaining this state, lowering the second support, the reactor core tube is lowered. The other end was fully immersed into the liquid in the liquid bath, and while maintaining that state, the first support was lowered, thereby being partially immersed in the liquid in the liquid bath. The method for cleaning a furnace core tube is characterized in that one end of the furnace core tube is completely immersed in the liquid in the liquid tank.

Reference Example 1 FIGS. 3 and 4 show a core tube cleaning device that is a reference example of the present invention. In this reference example, in the core tube cleaning apparatus shown in FIGS. 1 and 2, the structure of the third cleaning tank 3 is partially improved, and the transfer mechanism including the arm 7 that supports the core tube 4 is improved. It is something. That is, four rollers 5 are mounted on the bottom plate 13 of the third cleaning tank 3, and each pair of two rollers 5 supports the vicinity of both ends of the furnace tube 4, respectively. Also,
One connecting shaft 14 passes through the center of the two rollers 5 located on one side in a fixed state. This connecting shaft 14 is connected via a coupling ring 18 to a rotating shaft 17 of a motor 16 disposed under a cover 15 on one end side of the third cleaning tank 3, and is rotated by the drive of the motor 16. ing. Therefore, the furnace tube 4 is placed on the roller 5 and the motor 16 is
When driven, the furnace core tube 4 is rotated by the rollers 5.

Furthermore, a pure water injection mechanism 19 is provided on the cover 15 side of the third cleaning tank 3 to spray a cleaning liquid made of pure water. This pure water injection mechanism 19 consists of a jet nozzle 20 that spouts out pure water, and a supply pipe 21 that guides the pure water to the jet nozzle 20.
The jet nozzle 20 also has a swinging portion 22 that swings the jet nozzle up and down.

Furthermore, an injection pipe 6 having a plurality of injection holes (not shown) for spraying pure water onto the reactor core tube 4 placed on the roller 5 is arranged at the upper part of the inner wall on both sides of the third cleaning tank 3. .

On the other hand, the transfer mechanism for transferring the furnace core tube 4 has a structure shown in FIG. That is, the first cleaning tank 1
- Two rails 23 are arranged above the third cleaning tank 3 so as to cross them together, and these rails 23
3, a movable box 24 is mounted on wheels 25. The rotation of this wheel 25 is controlled by a motor system (not shown). Further, from the bottom surface of the movable box 24, the lower end thereof is bent in an arc shape, and two arms 7 on which the reactor core tube 4 is placed extend from the bent portion. The upper ends of these arms 7 are each connected to a lifting plate 26 inside the movable box 24.
is fixed and supported. These elevating plates 26 are connected to two guides 2 extending vertically within the movable box 24.
7 is slidably fitted. In addition, the elevating plate 26
A threaded rod 28 parallel to the guide 27 is screwed into the screw rod 28, and the upper end of this threaded rod 28 is connected to a coupling ring 29.
It is connected to a rotating shaft 33 of a lifting motor 32 fixed to the upper surface of a ceiling plate 30 of the movable box 24 via a support plate 31. Therefore, the arm
In a support mechanism consisting of an elevating plate, a threaded rod, a motor, etc., when the elevating motor 32 is rotated in the normal direction, the elevating plate 26 is lowered, so that the arm 7 is also lowered, and when the elevating motor 32 is reversed, the elevating plate 26 is lowered. 26 rises. Furthermore, the two arms 7 can be individually controlled to rise and fall.

〔Example〕

Next, a method for cleaning a core tube according to the present invention using such a core tube cleaning device will be explained in FIG. 6a.
This will be explained with reference to . First, after hooking the reactor core tube 4 to the arm 7 of the transfer mechanism, the transfer mechanism is stopped directly above the first cleaning tank 1, and the two sets of support mechanisms are raised and lowered as shown in Fig. 6a and b. Both motors 32 are rotated in the forward direction to lower the furnace core tube 4 while keeping it in a horizontal state. Then, when the lower surface of the furnace tube 4 comes into contact with the etching liquid 8, the lowering of the arm 7 of one support mechanism is stopped, and only the lowering of the arm 7 of the other support mechanism is continued. The stop-side arm 7 supports the branch pipe 10 side of the reactor core tube 4. Therefore, Figure c
As shown, the core tube 4 enters the etching liquid 8 from its large diameter portion. Since this large-diameter side is a straight circular tube, the etching liquid smoothly enters the tube without floating the tube.

Next, as shown in the figure d, the other arm 7
is stopped, one arm 7 is lowered, and the reactor core tube 4 is placed into the etching solution from its branch tube side. At this time, since the etching liquid also flows into the branch pipe from the large diameter side, the furnace core tube 4 does not float up and become sluggish. Further, when the branch pipe 10 reaches an inclined position below the large diameter portion of the core tube 4, the descent of one arm 7 is stopped, and the other arm 7, which has been in a stopped state, is gradually lowered. The reactor core tube 4 is lowered and stopped horizontally in the etching liquid 8, and the deposited layer inside the reactor core tube is etched. In this way, since the furnace core tube 4 is alternately tilted and immersed in the etching solution, no air bubbles remain in the furnace core tube.

Reference Example 2 Next, a furnace tube lifting operation that is a reference example of the present invention will be described. Here, when the undesired adhesion layer on the tube wall was dissolved by etching, the seventh
The furnace core tube 4 is lifted out of the etching solution according to the procedure shown in Figures a to d. That is, when the core tube is in a horizontal state in the etching liquid 8 as shown in FIG. Incline the furnace core tube 4 as shown in FIG. Next, both arms 7 are raised in this state. Then, the bottom surfaces of the inner walls of the core tubes through which the etching liquid flows are all sloped in the same direction, that is, the bottom surfaces are slanted upward to the left as shown in Figure c, and the etching liquid flows down from the tubes without being blocked. After the core tube 4 is lifted onto the etching solution in an inclined state, one arm 7 on the side of the branch tube 10 stops rising, and the other arm 7 rises, causing the core tube 4 to rise as shown in d in the same figure.
is in a horizontal state.

Next, the transfer mechanism moves and stops above the second cleaning tank 2, and the core tube 4 is immersed in the cleaning liquid (pure water) for a certain period of time in the same manner as described above to clean the inner and outer walls of the core tube. .

Next, the transfer mechanism transfers the reactor core tube 4 into the third cleaning tank 3, as shown in FIGS. 3 and 4.
The furnace core tube 4 is placed on the rollers 5 with its large diameter portion facing the jet nozzle 20 side. At this time, the bent portion of the arm 7 is slightly removed downward from the lower surface of the furnace core tube 4. Then, since the motor 16 is driven and the roller 5 rotates, the furnace core tube 4 rotates, and at the same time, pure water is blown out from the injection tube 6 to clean the outer peripheral wall of the furnace core tube 4. At the same time, pure water is also jetted from the jet nozzle 20, and this water stream hits the inner wall of the rotating reactor core tube 4. Further, since the swinging portion 22 of the jet nozzle 20 swings, the water flow moves along the generatrix of the core tube, so that the entire inner wall of the core tube 4 is cleaned due to the rotation of the core tube. In addition, the water flow hits the inner wall of the constrictor and the inner wall of the branch pipe with great force, allowing for effective cleaning.
Note that the dirty cleaning liquid is drained from the drain port 34. After cleaning for a certain period of time in this way, the injection of pure water from the jet nozzle 20 and the injection pipe 6 is stopped, and the rotation of the motor 16 is also stopped. and,
The arm 7 rises and the cleaned furnace core tube 4 is carried to a predetermined position, completing a series of cleaning operations.

〔effect〕

According to this embodiment, the furnace core tube can be immersed in the etching solution and the cleaning solution without leaving any air remaining in the tube.

In addition, since the structure allows the core tube to be tilted appropriately when immersing it in the liquid, air bubbles may remain inside the tube during immersion, or the core tube may float on the liquid surface and cause the arm to immerse. It will not move against you. Therefore, the uniformity of etching and cleaning can be maintained.

As described above, according to the cleaning method of the present invention, sufficient cleaning can be performed and work efficiency can be increased.

[Brief explanation of drawings]

1 and 2 are partial explanatory diagrams of the core tube cleaning device, and FIG. 1 is an operational diagram showing the cleaning operation;
FIG. 2 is a partial sectional view showing the state of cleaning inside and outside the reactor core tube in the third cleaning tank. 3 to 5 and 7 are diagrams showing reference examples of the present invention, and FIG. 6 is a diagram showing an embodiment of the present invention. 1...First cleaning tank, 2...Second cleaning tank, 3...
Third cleaning tank, 4... Core tube, 5... Roller, 6...
...Injection pipe, 7...Arm, 8...Etching liquid,
9...Cleaning liquid, 10...Detail pipe (branch pipe), 11...
...Rotating joint, 12...Pure water supply pipe, 13...
...Bottom plate, 14...Connection shaft, 15...Cover, 16
... Motor, 17 ... Rotating shaft, 18 ... Coupling, 19 ... Pure water injection mechanism, 20 ... Jet nozzle, 21 ... Supply pipe, 22 ... Oscillating part, 23
...Rail, 24...Movable box, 25...Wheel, 2
6... Elevating plate, 27... Guide, 28... Threaded rod, 29... Coupling, 30... Ceiling plate, 3
1... Support plate, 32... Lifting motor, 33...
Rotating shaft, 34...Drain port.

Claims (1)

[Scope of Claims] 1. A method for cleaning a furnace core tube in which the furnace core tube is cleaned by immersing the furnace core tube in a liquid tank containing a liquid, wherein the furnace core tube is cleaned near one end and the other end. are supported by first and second supports, respectively, and the reactor core tube is moved to near the liquid level of the liquid tank by the first and second supports, and the first support is lowered. One end of the reactor core tube is partially immersed in the liquid of the liquid bath, and the other end of the reactor core tube is lowered by lowering the second support while maintaining that state. lowering the first support while fully immersed in the liquid of the liquid bath, thereby causing one end of the reactor core tube to be partially immersed in the liquid of the liquid bath; A method for cleaning a reactor core tube, comprising completely immersing it in the liquid in the liquid tank. 2. The method of cleaning a reactor core tube according to claim 1, wherein the liquid is an etching liquid.