JPH03126876A - Production device for silicon carbide film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used for forming a silicon carbide coating on the inner surface of a cylindrical substrate such as a reaction tube for a diffusion furnace for heat-treating semiconductors. The present invention relates to a silicon carbide film manufacturing apparatus.

[Prior Art and Problems to be Solved by the Invention] As a reaction tube for a semiconductor diffusion furnace, it is preferable to use a cylindrical silicon carbide substrate with a high-purity silicon carbide coating formed on the inner surface.
When manufacturing such a reaction tube, a method of forming a high-purity silicon carbide coating on the inner surface of the substrate is to supply a raw material gas containing a silicon source and a carbon source into the substrate, and heat it under normal pressure or reduced pressure. Chemical vapor deposition (chemical vapor deposition) in which a silicon carbide film is deposited on the inner surface of the substrate using
CVD') method is commonly used.

However, the silicon carbide film obtained by such a method is inferior in density, uniformity, and homogeneity, and may cause problems such as breakage and peeling. That is, when forming a silicon carbide film on the inner surface of a long cylindrical substrate such as a reaction tube for a diffusion furnace by chemical vapor deposition, a raw material gas is supplied from an opening at one end of the cylindrical substrate under heating. In this case, the film tends to be thick near the raw material gas supply part, that is, on one end side, and changes in reaction conditions also affect M&D density, resulting in poor density and uniformity.

It is difficult to obtain a coating with high homogeneity. For this reason,
A reaction tube for a semiconductor diffusion furnace in which a film is formed by such a method is susceptible to breakage and peeling of the film during heat treatment of the semiconductor, and the passage and diffusion of impurities may contaminate the semiconductor inside.

In order to solve such problems, a cylindrical electrode is placed inside a cylindrical outer shell, a silicon carbide tube to be treated is placed inside the cylindrical electrode, and the raw material gas is introduced into the silicon carbide tube from one end side. The inside of the cylindrical electrode is induction-heated in a band-like manner by a ring-shaped induction heater movably disposed around the outer periphery of the outer shell, and the induction heater is moved along the outer shell to perform heating. A film forming apparatus has been proposed in which the zone, that is, the reaction region is moved to prevent differences in film thickness and density between the end on the raw material gas supply side and the other end (Japanese Patent Publication No. 60-6304). Publication No.).

However, in this apparatus, since the induction heater moves along the object to be treated, variations in film thickness that occur in the circumferential direction due to the positional relationship between the gas flow and the object to be treated extend to the axial direction. It has a drawback that the film thickness tends to be non-uniform over the entire film.

The present invention was made in view of the above circumstances, and even if it is a long cylindrical object, the entire inner surface of the object is highly uniform and homogeneous in both the axial direction and the circumferential direction. An object of the present invention is to provide a silicon carbide film manufacturing apparatus that can reliably form a pure silicon carbide film and is suitably used for manufacturing a silicon carbide reaction tube for a semiconductor diffusion furnace.

[Means to solve the problem]

In order to achieve the above object, the present invention provides an apparatus for forming a high-purity silicon carbide coating on the inner surface of a cylindrical workpiece by chemical vapor deposition, the invention comprising a cylindrical reaction tube in which the workpiece is housed. It is arranged and fixed from the base end to the distal end of the reaction tube, and is configured so that the heat generation can be controlled on and off along the axial direction, and partially heats the object to be treated in a band-like manner. a heating mechanism that heats the object to be processed in a time-difference manner by moving the heating region; and a gas supply mechanism that supplies a raw material gas containing a carbon source and a silicon source into the object to be processed housed in the reaction tube. The present invention provides a silicon carbide film manufacturing apparatus comprising: a rotation mechanism for rotating the object to be processed;

[For production]

When forming a silicon carbide film on the inner surface of a cylindrical workpiece using the silicon carbide film manufacturing apparatus of the present invention, after the workpiece is accommodated in a reaction tube, a part of the workpiece is heated by a heating mechanism. At the same time as heating in a band shape, the gas supply mechanism is operated to supply a raw material gas consisting of a carbon source and a silicon source into the workpiece, and the one-rotation mechanism is operated to rotate the workpiece around its center axis. While rotating slowly, the belt-shaped heating zone is moved to chemically vapor deposit silicon carbide on the entire inner surface of the cylindrical object to form a silicon carbide film.

At this time, it is preferable to reduce the pressure inside the reaction tube.

According to the silicon carbide film manufacturing apparatus of the present invention, the cylindrical workpiece is rotated by the rotation mechanism, so that the generated silicon carbide film is even and homogeneous in the circumferential direction of the workpiece. becomes. Furthermore, since the heating zone (reaction area) moves,
When the raw material gas is supplied from one end of the cylindrical object, the reaction region moves continuously. In other words, even on the other end side (raw material gas discharge end side), only this part is heated in a band shape, and by moving this heating zone (reaction area), the same conditions are maintained from one end side to the other end side. Therefore, a uniform silicon carbide coating can be obtained on the inner surface of the cylindrical object in the axial direction. In this case, in the silicon carbide film manufacturing apparatus of the present invention, the heating mechanism is arranged and fixed from the base end to the distal end of the reaction tube, so that heat generation can be controlled on and off along the axial direction of the reaction tube. Since the heating mechanism itself does not move, and the heating zone moves by controlling the heat generation on and off, it is easy to measure the heating temperature of each part, and the heating temperature of the heating zone can be controlled reliably. Therefore, it is possible to more reliably form a uniform and homogeneous silicon carbide film in the axial direction.

Therefore, by using a silicon carbide tube as the object to be treated, a semiconductor diffusion furnace can be used that does not cause inconveniences such as damage or peeling of the coating, or contaminate the internal semiconductor due to the passage or diffusion of impurities during heat treatment. A silicon carbide reaction tube can be obtained.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

〔Example〕

The drawing shows a silicon carbide film manufacturing apparatus according to an embodiment of the present invention, which is suitably used to form a high-purity silicon carbide film on the inner surface of a cylindrical silicon carbide substrate of a reaction tube for a semiconductor diffusion furnace. It is something that will be done. This silicon carbide membrane production bag H1 has a fitting hole 4 bored in the earthen wall of a base 3 in which a hollow part 2 is formed.
A large-diameter cylindrical pedestal 5 on which a lower small-diameter cylindrical portion is fitted and fixed.
The reaction tube 6 is provided with a cylindrical reaction tube 6 which is erected with its lower end fitted into a ring-shaped recess formed on the upper end surface of the pedestal 5. This reaction tube 6 is made of quartz or the like, and a cylindrical graphite electrode 7 is arranged and fixed in the reaction tube 6 along its axial direction, and between this electrode 7 and the reaction tube 6 A heat insulating layer 8 is formed by interposing a heat insulating material such as carbon fiber.

Further, a water-cooled induction coil 9 for inductively heating the electrode 7 is disposed outside the reaction tube 6, and the water-cooled induction coil 9 is heated by an energization switching device 10.

Electricity can be turned on and off along the axial direction. Therefore, the coil 9 is constructed so that it can be partially energized and the energized area can be moved by operating the switching device 10, and thereby the electrode 7 is controlled to turn on and off heat generation along the axial direction. Electrode 7
It is configured so that it can be partially heated in a band-like manner, and this band-like heating section can be moved.

The upper end opening of the first reaction tube 6 is hermetically closed by a lid 12 having an exhaust pipe 11 in the center via a ring (not shown). Although this exhaust pipe 9 is not shown, it is connected to a vacuum pump, and the pressure inside the reaction tube 6 can be reduced by operating the vacuum pump. In addition, the reaction tube 6 is connected to the arm 1 by two supports 13 and 13 erected on the base 3 at a predetermined distance from each other.
4. ．． It is firmly fixed via 14.

The base 3 has the hollow portion 2 formed therein as described above, and the center portion of the pedestal 5 is provided with a through hole 15 that communicates with the hollow portion 2. 15
A cylindrical rotating shaft 17 rotatably supported by bearings 16, 16 embedded in the pedestal 5 is rotatably disposed, and the tip of the rotating shaft 17 protrudes from the pedestal 5 and is connected to the reaction tube. It is inserted in the lower part of 6. On the other hand, the proximal end protrudes into the hollow portion 2, and a pulley 18 is attached to this protruding proximal end. In addition, the base 3 is equipped with a deceleration motor 9.
- is fixed, its rotating shaft 20 protrudes into the hollow part 2, a pulley 21 is attached to the tip thereof, and a driving belt 22 is wound between the rotating shaft 17 and the pulley 18. The pulley 21 is rotated by the operation of the deceleration motor 19, and the rotary shaft F is rotated together with this rotation via the belt 22 and the pulley 18. Note that a cylindrical workpiece 23 is fixed to the tip of this rotating shaft 17, and
7, a pedestal 24 disposed below the rotating shaft 17 and a through hole bored in the bottom wall of the pedestal supply raw material gas containing a carbon source and a silicon source into the object to be processed 23. Raw material gas supply path 2
5 is formed.

Next, when forming a high-purity silicon carbide film on the inner surface of the cylindrical silicon carbide substrate (workpiece) 23 of a reaction tube for a semiconductor diffusion furnace using the silicon carbide film manufacturing apparatus 1, the lid body 12 is The substrate 23 is accommodated in the reaction tube 6 in the removed state, and
It is fixed to the distal end surface of the rotating shaft 17, and then the lid body 12 is attached to the reaction tube 6, and after closing the upper end opening, the exhaust pipe 1 is closed.
1, the air inside the reaction tube 6 is exhausted by a vacuum pump to reduce the pressure inside the reaction tube 6. While maintaining this reduced pressure state, the upper end of the electrode 7 is heated by operating the switch 110 to partially energize the upper end of the water-cooled induction coil 9, thereby forming the upper end of the object 23 into a band shape. While heating, a raw material gas containing a carbon source and a silicon source is supplied into the workpiece 23 through the raw material gas supply path 25 . In addition, by operating the deceleration motor 19 and slowly rotating the rotary shaft 17, the object to be processed 23 is slowly rotated within the reaction tube 6 together with this rotation. As a result, the object to be processed 2
A silicon carbide film is deposited on the upper end of the electrode 7. In this state, the heating area of the electrode 7 is moved by operating the energization switching device IO to move the energization area of the water-cooled induction coil 9 downward at a predetermined speed. As the object 23 moves, the heating zone (reaction area) for the object 23 is moved from the upper end to the lower end.

A silicon carbide film is sequentially vapor-deposited over the entire inner surface of the object 23 from its upper end to its lower end.

In this case, the yK source gas contains a carbon source and a silicon source, and specifically, methyltrichlorosilane or the like is preferably used, and in this case, hydrogen gas is usually used in combination as a carrier gas. .

Moreover, the carbon source and the silicon source can also be supplied from separate gases. In this case, by forming the raw material gas supply path 25 into a double structure, an arbitrary carrier gas flow rate can be easily selected for the raw material gas.

In addition, two types of raw material gas can be supplied separately, and the supply 125
This has advantages such as being able to prevent reactions within the reaction tube and supplying gas at a set flow rate into one reaction tube. The heating temperature inside the reaction tube is
The temperature can be set at 1100 to 1500°C, and the pressure inside the reaction tube is preferably reduced to about 1 to 100 Torr. Furthermore, the rotational speed of the rotating shaft 17 must be determined taking into account the shape of the object to be treated, but is preferably about 1 rpm, and the moving speed of the heating region is determined by the coil pitch. But usually 2hr/200u
It is said to be about yn.

According to the silicon carbide film manufacturing apparatus 1, the heating zone (reaction region) of the object to be processed 23 is moved from above to below, and the silicon carbide film is sequentially formed on the inner surface of the object to be processed 23 from the upper end to the lower end. Since phase deposition is performed, fresh raw material gas can be reliably and stably supplied to the reaction region, whether on the raw material gas supply end side or the raw material gas discharge end side of the object to be processed. That is, when forming a film on the raw material gas discharge end side, only this part is heated in a band shape, and no reaction area is formed in other parts, so this heating zone (reaction area)
The carbon source and silicon source in the raw material gas are not consumed at the raw material gas supply end of the object to be processed until it reaches the raw material gas, and the raw material gas is supplied in a fresh state. Therefore, good film formation is achieved even on the source gas discharge end side.

Moreover, by moving this heating zone (reaction area) and sequentially performing vapor phase deposition from one end of the object to the other,
Since a silicon carbide film is formed on the entire inner surface of the object to be processed, vapor phase deposition can be performed under the same conditions from one end to the other. A silicon carbide film that is uniform and homogeneous in the axial direction can be obtained on the inner surface.

Further, in this case, since the vapor phase deposition is performed while rotating the object to be treated, it is possible to form a uniform and homogeneous coating even in the circumferential direction of the inner surface of the object to be treated. Furthermore, the silicon carbide film manufacturing apparatus 1 has a water-cooled induction coil 9 disposed outside the reaction tube 6 as a heating mechanism.
The electrode 7 disposed in the reaction tube 6 is selectively heated in a zone by partially energizing at 0, and the mechanism moves through this heating zone by operating the switching device 10. This makes it easy to measure temperature from the side.
For example, by attaching a branch pipe to the cylindrical reaction tube 6,
Light thermometers and thermocouples can be brought close to the object to be processed over a short distance.

By such a method, it is possible to easily and accurately measure the temperature of any part of the object to be processed from one end to the other end. Therefore, by performing such temperature measurement, temperature control can be performed more reliably, and a coating with higher uniformity and homogeneity can be obtained.

Therefore, according to the silicon carbide film manufacturing apparatus 1 of this example, a uniform silicon carbide film is formed on the entire inner surface of the long cylindrical workpiece 23 in both the axial direction and the circumferential direction. Therefore, by using a silicon carbide tube as the object to be processed 23, problems such as damage or peeling of the film will not occur, and the internal semiconductor will not be contaminated by the passage or diffusion of impurities during heat treatment. A silicon carbide reaction tube for a semiconductor diffusion furnace can be obtained.

Note that the silicon carbide film manufacturing apparatus of the present invention is not limited to the above-mentioned embodiments, and for example, the heating mechanism may be replaced with induction heating by other methods such as resistance heating, infrared radiation heating, laser beam heating, etc. There is no problem in using a mechanism or arranging the reaction tube horizontally, and the mechanism for rotating the object to be treated, the shape of each member, their arrangement, etc. may be changed in various ways within the scope of the gist of the present invention. do not have.

〔Effect of the invention〕

As explained above, according to the silicon carbide film manufacturing apparatus of the present invention, even if a long cylindrical workpiece is processed, the entire inner surface of the workpiece is uniform and homogeneous in both the axial direction and the circumferential direction. A dense silicon carbide film can be formed by using a silicon carbide tube as the object to be treated, and there is no risk of inconveniences such as damage or peeling of the film, or contamination of the internal semiconductor due to the passage or diffusion of impurities during heat treatment. This makes it possible to obtain a silicon carbide reaction tube for a semiconductor diffusion furnace that does not cause any damage.

Hereinafter, the present invention will be specifically explained with reference to experimental examples.

[Experiment example]

Using the silicon carbide film manufacturing apparatus 1 shown in the above embodiment, the graphite electrode 7 has an inner diameter of 150 nwnφ.

Silicon carbide tube 2 with an outer diameter of 160nwnφ and a length of 2000mm
3 was loaded, and its base end was fixed to the tip of the rotating shaft 17.

Next, the upper end opening of the reaction tube 6 was airtightly closed with the lid 12, and then the air inside the reaction tube 6 was evacuated from the upper part of the exhaust tube 1 using a vacuum pump to reduce the pressure inside the tube. Next, the water-cooled induction coil 9
Electricity was applied to the upper end to heat the upper end of the electrode 6 by induction, and the inside of the reaction tube 6 was adjusted to 50 Torr while hydrogen gas was flowing into the silicon carbide tube 23 at a rate of 6000 d/win through the gas supply g25. Thereafter, the upper end of the silicon carbide tube 23 is heated to 1300° C., and hydrogen gas and methyltrichlorosilane are respectively supplied through the gas supply path 25 at 60° C.
000 d/win and 5 Q mQ/ll1i
While flowing into the silicon carbide tube 23 at a flow rate of n, the deceleration motor 19 is operated so that the silicon carbide tube 2 is
3 at a constant speed, and the energization switching machine 1
0 to move the heating section continuously from the upper end to the lower end at a constant speed to obtain a silicon carbide reaction tube whose inner surface was covered with a dense silicon carbide film. When the silicon carbide film formed on the inner surface of this reaction tube was examined, it was confirmed that the film was uniform and homogeneous both in the axial direction and in the circumferential direction.

[Brief explanation of the drawing]

The drawing is a sectional view showing an embodiment of the present invention. 1...Silicon carbide film manufacturing equipment 7...Graphite electrode 10... Energization switching machine 1.9...Deceleration motor 25... Raw material gas supply path 6...Reaction tube 9...Water-cooled induction coil F...Rotation axis 23... Object to be treated

Claims (1)

[Claims] 1. This is an apparatus for forming a high-purity silicon carbide coating on the inner surface of a cylindrical workpiece by chemical vapor deposition, which includes a cylindrical reaction tube in which the workpiece is accommodated, and a cylindrical reaction tube that includes a base end to a distal end of the reaction tube. It is arranged and fixed over the entire area, and is configured to be able to control on/off of heat generation along the axial direction, so that the object to be processed is partially heated in a band shape, and by moving this heating area, the object to be processed can be heated in a time-differential manner. A heating mechanism for heating the object to be processed, a gas supply mechanism for supplying a raw material gas containing a carbon source and a silicon source into the object to be processed housed in the reaction tube, and a rotation mechanism for rotating the object to be processed. A silicon carbide film manufacturing apparatus comprising: