JPH0590186A - Vertical heat-treating device - Google Patents

Abstract

(57) [Summary] [Object] To provide a vertical heat treatment apparatus capable of preventing the formation of a volume on the inner wall surface of a reaction tube. A gas introducing pipe 34 for introducing a processing gas into the reaction tubes 14 and 16 is provided on the object to be processed (semiconductor wafer) 20.
And the inner wall surface 57 of the inner reaction tube 16 are extended to form a rectifying member 52 on the inner wall surface side of the reaction tube at the tip of the gas introduction tube 34, and the processing gas released is rectified to form the inner wall surface of the reaction tube. Avoid direct contact between 57 and gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical heat treatment apparatus.

[0002]

2. Description of the Related Art Generally, a heat treatment apparatus is known as an apparatus for subjecting an object to be processed such as a semiconductor wafer to a predetermined heat treatment in a uniform temperature state to form a thin film on the surface or to perform heat diffusion. There is. A general heat treatment apparatus of this type accommodates a large number of semiconductor wafers stacked on a wafer boat in a reaction tube made of a heat-resistant material such as quartz, and supplies a predetermined processing gas into the reaction tube while a predetermined processing gas is supplied. The heat treatment is performed at a pressure and a predetermined temperature.

[SUMMARY OF THE INVENTION Incidentally, in the case of forming a thin film such as silicon dioxide (S _i O ₂₎ on the surface of the semiconductor wafer, silane as the process gas, TMP (trimethyl phosphite), TMB (trimethyl borate ), T
EOS (tetraethyl orthosilicate) or the like is supplied into the reaction tube through the gas introduction tube. Then, the supplied processing gas comes into contact with a large number of semiconductor wafers stacked at a predetermined pitch on the wafer boat to form silicon dioxide or the like on the wafer surface.

Due to the demand for miniaturization of the heat treatment apparatus itself, as shown in FIG. 9, the distance between the semiconductor wafers 4 stacked on the wafer boat 2 and the inner wall surface 6 of the reaction tube is very small. The distance between the gas introduction pipe and the inner wall surface 6 installed therebetween is also very narrow, and there is a gap of only a few mm, for example. Therefore, the processing gas G introduced from the upper end portion of the gas introduction pipe 8 is immediately opened and spreads to the periphery to come into contact with the inner wall surface 6, thereby forming an unnecessary volume 10 of silicon dioxide in this portion. Was. Then, during repeated heat treatment operations, the above-mentioned volume separated and became particles, which were scattered and adhered to the surface of the semiconductor wafer, causing a reduction in yield. Further, as the volume 10 grows, as shown in the figure, the processing gas G introduced therein comes into contact with the gas and causes the gas to flow unevenly. It had an improvement point that the uniformity deteriorated.

Further, normally, in order to remove the thin film adhering to the inner wall surface 6 of the reaction tube or the wafer boat 2, a cleaning gas or the like is periodically passed to perform a cleaning operation, and further, a cleaning operation is performed every appropriate number of times. In addition, the system itself is brought down and the reaction tube and the wafer boat are removed for cleaning, but when the volume 10 as described above is generated, there is a disadvantage that the frequency of the cleaning operation or the cleaning operation increases. In particular, once the system is brought down for the cleaning operation, it takes one day or more to restart the system, resulting in an increase in the total downtime of the system and a reduction in throughput. The present invention was created to solve the above problems. An object of the present invention is to provide a vertical heat treatment apparatus capable of preventing deposition on an inner wall surface of a reaction tube by depositing an unnecessary volume on the side of a gas introduction tube which is easily removable.

[0005]

In order to solve the above problems, the present invention provides a vertical heat treatment apparatus including a reaction tube for heat-treating an object to be processed and a gas introduction tube for introducing a processing gas into the reaction tube. In the above, the gas introduction pipe is extended from a lower portion of the reaction pipe toward a gap between the object to be treated and the inner wall surface of the reaction pipe, and is provided on a reaction pipe inner wall surface side of a tip portion of the gas introduction pipe. It is configured such that a rectifying member that rectifies the process gas introduced into the reactor and prevents the gas from accumulating on the inner wall surface of the reaction tube is provided.

[0006]

Since the present invention is constituted as described above, the processing gas introduced into the reaction tube through the gas introducing pipe is guided along the rectifying member provided at the tip of the gas introducing pipe. Since the current is rectified and flows upward, the occurrence of uneven flow is suppressed. In addition, since unnecessary deposits are formed on the rectifying member, it is possible to suppress the possibility of forming unnecessary deposits on the inner wall surface of the reaction tube. Unnecessary deposits formed on the rectifying member are easily removed by removing and cleaning the gas introduction pipe that can be attached and detached without shutting down the system.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the vertical heat treatment apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. As shown in FIGS. 1 and 2, the vertical heat treatment apparatus 12 has an outer reaction tube 14 formed of a heat-resistant material, for example, quartz, into a cylindrical shape and having an upper end closed and a lower end open. Inside the outer reaction tube 14, for example, a cylindrical inner reaction tube 16 having upper and lower ends opened by quartz is concentrically provided to form a double tube structure. A wafer boat 18 made of, for example, quartz is provided in the inner reaction tube 16.
An object to be processed, for example, a semiconductor wafer 20, which is stacked and mounted in a vertical direction at a predetermined pitch, is housed in a removable manner. A resistance heater 22 is coaxially provided on the outer periphery of the outer reaction tube 14 so as to cover the outer reaction tube 14, and the outer periphery of the heater 22 is made of, for example, stainless steel through a heat insulating material 24. A cylindrical outer shell 26 is provided and forms a heating furnace as a whole. Then, by controlling the heating heater 22, the reaction tube is, for example, 300-1200.
It can be set appropriately within the range of ° C.

At the lower end of the outer reaction tube 14, a cylindrical manifold 28 made of, for example, stainless steel is connected as a sealing body, and an annular flange is provided at the upper end of the manifold 28. The portion 30 is formed, and the flange portion 30 is provided with, for example, an O-ring 32 as a sealing member made of an annular elastic member to hermetically seal the inside. The manifold 28 supports the lower end of the inner reaction tube 16, connects one end of the manifold 28 with a gas introduction pipe 34 for supplying a processing gas, and connects the other end to a vacuum pump (not shown). Is connected to an exhaust pipe 36, and the inside of the reaction pipe can be evacuated.

The wafer boat 18 is mounted on a heat retaining cylinder 38 made of, for example, quartz, and the heat retaining cylinder 38 hermetically seals the lower end opening of the manifold 28 via an O-ring. It is rotatably supported by a cap portion 40 which is a lid body made of, for example, stainless steel. The cap portion 40 is held by an elevating mechanism 42 such as a wafer elevator so that the wafer boat 18 can be loaded and unloaded in the inner reaction tube 16. on the other hand,
The gas introduction pipe 34 is bent, for example, in an L shape with quartz or the like, and is connected to an external gas pipe 46 made of, for example, stainless steel via a joint 44 at a penetrating portion of the manifold 28. As shown in FIG. 4, the joint 44 has a hollow cylindrical casing 48 in which a screw portion is formed,
The gas inlet pipe 34 and the gas pipe 46 can be hermetically joined by screwing the base end portion 34a of the gas inlet pipe 34 into the screw portion formed on the manifold 28 side in a state of being inserted thereinto. It is configured. In addition, 50 in FIG.
Is an O-ring that maintains the airtightness.

The gas introducing pipe 34 extends upward from the lower portion of the inner reaction pipe 14 and is located in the gap between the inner reaction pipe 14 and the semiconductor wafer 4. As shown in FIGS. 2 and 3, at the tip of the gas introducing pipe 34, the gas introducing pipe 34 is inclined with respect to its longitudinal direction and cut into an elliptical cross section, which is a feature of the present invention. A rectifying member 52 is provided.
Therefore, the rectifying member 52 is provided so as to extend the inner wall surface side of the reaction tube at the tip end portion of the gas introducing pipe 34, and is formed as a rectifying member having an arcuate cross section which is gradually reduced as it goes upward. The processing gas G discharged from the discharge port 55 can be rectified upward without being biased. The shape of the opening of the gas introduction pipe 34 may be any shape as described later,
The length L1 between the lower end 54 of the opening and the upper end 56 of the rectifying member 52 is not limited. For example, the longer it is, the more rectifying action is exhibited and the formation of deposits on the inner wall surface of the reaction tube is prevented. can do.

Next, the operation of the present embodiment constructed as above will be described. First, the wafer boat 18 in which a large number of semiconductor wafers 20 are accommodated at a predetermined pitch is lifted by the lifting mechanism 4
2 into the reaction tubes 14, 16 and the cap portion 4
0 closes the opening of the manifold 28 to seal the inside of the reaction tube. Then, a predetermined amount of processing gas, for example, TEOS, is supplied from the gas introduction pipe 34, the exhaust pipe 36 is evacuated by a vacuum pump (not shown), and the reaction pipe has a predetermined pressure
For example, it is set to 1 Torr. Further, while maintaining the inside of the reaction tube at a predetermined temperature, for example, 400 ° C. by the heater 22, the TEOS is supplied at, for example, about 100 cc / min, and nitrogen such as other carrier gas is supplied at about 20 liters / min for a predetermined time. Do.

During the film forming process, the semiconductor wafer 20 is rotated by rotating the wafer boat 18. During the film forming process, when the processing gas G introduced from the gas introduction pipe 34 is released from the tip emission port 55 of the gas introduction pipe 34 into the reaction pipe, the rectification extending in the emission direction, that is, upward. While being rectified by the member 52 and rising as a laminar flow, a part thereof also flows into the semiconductor wafer 20 side, and a film is formed on this surface.
The rectifying action at this time is shown in FIG. 5, and the process gas G released from the outlet 55 does not spread to the inner wall surface side of the reaction tube due to the action of the rectifying member 52, and is prevented from coming into direct contact with the inner wall surface. To be done. Therefore, formation of a volume on the inner wall surface 57 of the reaction tube can be suppressed. On the other hand, in the conventional structure shown in FIG. 6, as soon as the processing gas G is discharged from the discharge port 9, the processing gas G comes into contact with the inner wall surface of the reaction tube to form the volume 10 as shown in FIG. 9 as described above. However, such a phenomenon is prevented in the present embodiment.

In this case, the effective length L of the straightening member 52 is L.
1 depends on the supply amount of the processing gas, the processing pressure, etc., but the same length as the length of the volume 10 formed in the conventional structure,
For example, it may be set to about 300 mm. By the way, when the film forming process is performed to some extent, the rectifying member 52
The volume 60 tends to be formed in the vicinity of the upper end portion 56 of the above, but at an early time when the film forming process is not adversely affected, only the gas introduction pipe 34 is removed and this cleaning process is performed to remove the volume 60. To do. In this case, the wafer boat 18 is unloaded and positioned below the inner reaction tube 16, and in this state, the casing 48 of the joint 44 is rotated to loosen it so that the gas introduction tube Remove 34. Thus, the inner and outer reaction tubes 16,
The volume can be removed by removing the gas inlet pipe 34 and cleaning it without removing 14 or bringing down the system itself.

Thus, in order to remove the volume,
Since only the gas introduction pipe 34 that can be easily attached and detached and does not need to bring down the system can be removed and dealt with, the downtime of the system can be significantly reduced. As described above, since the volume 60 is dealt with promptly as described above, a biased flow that adversely affects the film formation with respect to the released processing gas does not occur. It is also possible to improve the in-plane and inter-plane uniformity of the thin film formed on the surface. In the above embodiment, the rectifying member 52 has a shape such that the gas introducing pipe 34 is cut obliquely, but the present invention is not limited to this, and the rectifying member 52 may be configured as shown in FIGS. 7 and 8, for example. Good. That is, FIG. 7 (a) is a perspective view of another embodiment, and FIG. 7 (b) is a side view thereof. The gas introduction pipe 34 is cut in a semicircular shape to the central portion, and is directed upward. And cut along the longitudinal direction of the pipe to form a straightening member 70 having a semicircular cross section. The length L2 of the rectifying member 70 at this time is also arbitrary, and is set to, for example, about 300 mm.

FIG. 8 (a) is a perspective view of still another embodiment, and FIG. 8 (b) is a side view thereof. The straightening member 72 of this embodiment is formed by obliquely cutting the upper end portion of the straightening member 70 having a semicircular cross section shown in FIG. 7 as in the embodiment shown in FIG. Also in this case, the length L3 of the main body of the rectifying member 72 and the length L of the tip end portion
4 is arbitrary, for example, L3 + L4 = 300 m
Set to about m. Also, in the above embodiment, TE
Has been described the case of forming a silicon dioxide (S _i O ₂₎ using the OS, not limited thereto, can be applied in the case of other process gases, such as silane, TMP, the TMB use,
Needless to say, it can be applied to the case of forming another film, for example, Al ₂ O ₃ , S _i , S _i3 N ₄ or the like.

[0016]

As described above, according to the present invention, the following excellent operational effects can be exhibited. Since the processing gas can be rectified and introduced into the reaction tube,
It is possible to suppress the formation of a volume on the inner wall surface of the reaction tube. Therefore, it is possible to suppress the generation of particles due to the peeling of the volume, and it is possible to improve the yield of semiconductor products. Further, even if a volume is generated, it can be removed by cleaning the gas introduction pipe, so that the total downtime of the system for cleaning can be greatly reduced. Further, since the volume does not grow excessively, it is possible to prevent the generation of a nonuniform flow of the processing gas and improve the in-plane and inter-plane uniformity of the processed film.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a vertical heat treatment apparatus according to the present invention.

FIG. 2 is an enlarged view of a main part showing a main part of a gas introduction pipe used in the present invention.

FIG. 3 is a perspective view showing an upper structure of a gas introduction pipe.

FIG. 4 is a cross-sectional view showing a mounting structure of a gas introduction pipe.

FIG. 5 is an explanatory view for explaining the action of the rectifying member provided in the gas introduction pipe used in the present invention.

FIG. 6 is an explanatory diagram illustrating the operation of a conventional gas introduction pipe.

FIG. 7 is a diagram showing another embodiment of the flow regulating member used in the present invention.

FIG. 8 is a view showing still another embodiment of the flow regulating member used in the present invention.

[Explanation of symbols]

 12 Vertical Heat Treatment Device 14 Outer Reaction Tube 16 Inner Reaction Tube 18 Wafer Boat 20 Semiconductor Wafer (Processing Object) 28 Manifold 34 Gas Introducing Tube 46 Gas Pipes 52, 70, 72 Rectifying Member 57 Inner Wall Surface 60 Volume

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] September 17, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Figure 9

[Correction method] Added

[Correction content]

FIG. 9 is an explanatory diagram for explaining a state in which a volume adheres in a conventional heat treatment apparatus.

Claims (1)

[Claims] 1. A vertical heat treatment apparatus comprising a reaction tube for heat-treating an object to be processed and a gas introduction tube for introducing a processing gas into the reaction tube, wherein the gas introduction tube is provided from a lower portion of the reaction tube to the object to be treated. Extending toward the gap between the body and the inner wall surface of the reaction tube, rectifies the process gas introduced into the inner wall surface side of the reaction tube at the tip of the gas introduction tube, and deposits on the inner wall surface of the reaction tube. A vertical heat treatment apparatus characterized in that a rectifying member for blocking is provided.