JPH01152630A - Pressure heat treating equipment - Google Patents

Abstract

PURPOSE:To further uniformize a produced film over a surface of the same way surrounding the whole surface of the produced film with high temperature process gas by disposing a back-flow member between a discharge part and a boar for preventing the process gas flowing in the vicinity of the discharge port from flowing back to the interior of a process tube. CONSTITUTION:A back-flow member 30 includes a back-flow plate 31 removably mounted on the tip end of a semi-spherical part 23 of a cap 21 and constructed substantially with a lower half of a disk. The back-flow plate 31 is adapted to partition a discharge port 15 and a boat 3 over a height from the vicinity of the bottom surface of a process tube 12 substantially to the center of a height of the process tube 12 along the cross section of the same. Even if process gas flowing in the vicinity of the discharge port 15 flows back, it can securely be prevented from reaching a wafer 2 mounted on the boat 3.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a pressurized heat treatment for forming a formed film such as an oxide film on an object to be processed by increasing the partial pressure of the atmosphere in a furnace. Regarding equipment.

(Prior art) In this type of pressurized heat treatment equipment, for example, a port on which a plurality of semiconductor wafers are mounted is placed in a furnace, and the open end of this furnace is sealed with a cap to separate oxygen and water vapor in the atmosphere. Examples include a high-pressure oxidation device that increases pressure to form an oxide film on the wafer.

A conventional example of this high-pressure oxidation apparatus will be explained with reference to FIG. 4. As shown in the figure, a quartz port 3 supporting a large number of semiconductor wafers 2 in an array is carried into a process tube 1. Later, the open end of the process tube 1 is sealed with a cap 4.

Then, the temperature inside the furnace is set to a predetermined temperature by the heater 5 disposed around the process tube 1, and a process gas is flowed in the direction of arrow A in the figure to form an oxide film on the semiconductor wafer 2. It has become.

Further, the process gas is discharged from a gas outlet 6 that is piped to the lower end of the process tube 1 on the side where the cap 4 is attached.

(Problems to be Solved by the Invention) In the conventional high-pressure oxidation apparatus described above, the semiconductor wafer 2
There was a problem in that the in-plane uniformity of the oxide film formed thereon was poor.

This poor in-plane uniformity is particularly noticeable on the side where the cap 4 is attached. More specifically, there is a phenomenon in which the oxide film is thicker at the upper end of the wafer and thinner at the lower end. there were.

For this reason, conventionally, 2, which is placed near this cap 4,
Measures were taken such as making three wafers dummy, but
Problems such as a decrease in the number of wafers 2 supported by the port 3 remained, and this method could not be said to be preferable from the viewpoint of improving yield.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a pressurized heat treatment apparatus capable of solving the above-mentioned conventional problems and improving the in-plane uniformity of a produced film formed on an object to be treated near the cap. There is a particular thing.

[Structure of the Invention] (Means for Solving the Problems) In the present invention, a plurality of objects to be processed are mounted on a port, this port is carried into a process tube of a heat treatment furnace, and this carrying-in 1] is carried out. In pressurized heat treatment equipment, which heats the object to be processed by introducing process gas from the back of the process tube while it is sealed with a cap and exhausting it from the discharge port provided on the loading port side, the process gas near the discharge port is used as a process gas. A backflow prevention member that prevents backflow to the back of the tube is arranged between the discharge port and the port.

(Function) The process gas introduced from the back of the process tube becomes relatively low in temperature near the discharge port provided at the port inlet end side of the process tube.

In particular, in this type of heat treatment apparatus, the heater arranged around the process tube cannot be extended to the vicinity of the discharge port due to its structure, so the discharge port is located at a part away from the position of the heater. In some cases, the above phenomenon is particularly noticeable.

Here, such relatively low-temperature process gas flows back to the location of the object to be processed, especially to the lower region of the object to be processed, which deteriorates the in-plane uniformity of the film formed on the object to be processed. The inventors have confirmed that this is the case.

Therefore, by arranging a backflow prevention member that prevents such backflow, it is possible to easily prevent the object to be processed from being immersed in the low-temperature process gas atmosphere without changing other conventional configurations. The in-plane uniformity of the film produced on the body can be significantly improved.

(Example) Hereinafter, an example in which the present invention is applied to a high-pressure oxidation apparatus for forming an oxide film on a semiconductor wafer will be specifically described with reference to the drawings.

The heat treatment furnace 10 is formed in a cylindrical shape using SO8, for example, and
It has an opening 11 at one end for carrying in a port 3 in which a plurality of semiconductor wafers 2 are arranged and supported at predetermined intervals.

A process tube 12 for forming an oxide film on the semiconductor wafer 2 is disposed within the heat treatment furnace 10 . The process tube 12 is formed of quartz into a cylindrical shape and has an inlet 12a for the port 3, and a heater 13 made of, for example, Kanthal wire is arranged around the cylindrical inlet 12a of the port 3. 900
It is possible to raise the temperature to °C.

Further, at the back of the process tube 12, a process gas is supplied to the inside of the process tube 12 at a predetermined pressure, e.g.
A gas inlet 14 is provided to introduce the gas at a pressure of about kg/atB G, and an outlet 15 for the process gas is provided at the bottom of the process tube 12 on the side of the inlet 12a. However, a soft landing mechanism is provided for carrying and placing the quartz port 3 into the process tube 12 using a fork, and then removing the fork from the process tube 12, and for loading and unloading the quartz port 3. It is executable.

Further, a cap member 20 for sealing the opening 11 of the heat treatment furnace 10 and the entrance 12a of the process tube 12 is provided.

This cap member 20 has a structure in which a cap 21 for sealing the entrance 12a and a lid part 25 for sealing the opening 11 are connected.

The cap 21 has a cylindrical portion 22 introduced into the process tube 12 with a tip end formed as a semicircular spherical portion 23, and this shape allows for a good flow of the process gas within the process tube 21. I take it as a thing.

Further, a sealing lid 24 is fixed to one end of the cylindrical portion 22, and the carrying-in port 12a of the process tube 12 is sealed by this sealing lid 24.

Next, the backflow prevention member 30, which is a characteristic configuration of this embodiment, will be explained.

This backflow prevention member 30 is detachably attached to the tip of the semicircular spherical portion 23 of the cap 21. That is, a U-shaped handle part 23a is fixed to the tip of the semicircular spherical part 23, and the backflow prevention member 30 can be locked to this handle part 23a. Note that the handle portion 23a is necessary only when the cap member 20 is attached to the device, and is not needed once it is attached. Therefore, as in this embodiment, the backflow prevention member 30 is attached to the handle portion 23a.
Even if it is installed, other operations will not be affected.

As shown in detail in FIGS. 2A and 2B, this backflow prevention member 30 has a backflow prevention plate 31 formed by approximately the lower half of a disk, and this backflow prevention plate 31 prevents the process tube Process tube 12 from near the bottom of 12
The discharge port 15 and the location of the port 3 can be partitioned by a height up to approximately the center of the cross-sectional height of the port 3.

Further, the backflow prevention plate 31 is fixed to a plate 33 by, for example, three support guide shafts 32. In this installation, the plate 33 has a locking portion 34 bent at right angles that is locked to the handle portion 23a, and the lower side of the locking portion 34 abuts against the semicircular spherical portion 23 to perform a rotation stopping function. For example, it is configured to include two stopper shafts 35.

A gap is provided between the lower end of the backflow prevention plate 31 and the bottom surface of the process tube 12 so as not to interfere with the process tube 12 when the cap member 20 is inserted or removed. .

Next, the effect will be explained.

First, to briefly explain the treatment process in this high-pressure oxidation apparatus, with the cap member 20 removed, the quartz port 3 is mounted with a fork (not shown) and carried into the process tube 12. Thereafter, the carried quartz port 3 is placed in the Proyas tube 12, and only the fork is removed from the process tube 12.

Next, the cap member 20 is moved to seal the lid 24.
The loading port 12a of the process tube 12 is sealed by this, and the opening 11 of the heat treatment furnace 10 is sealed by the lid 25, respectively.

By performing the sealing operation in this manner, it is possible to prevent contaminated surrounding gas from being introduced into the process tube 12, and also to prevent the leakage of water vapor that occurs during process execution within the process tube 12. The discharge port 15
The process tube 12, which is made of quartz, is prevented from being damaged by ensuring that the liquid is discharged only from the outside and by maintaining the pressure inside and outside the process tube 12.

After setting as described above, the oxidation sequence is started. An example of this oxidation sequence is as follows.

■ Set the pressure inside the process tube 12 to, for example, 0.4 atm/
The pressure is increased in minutes, and the temperature is increased by energizing the heater 13.

■Try to stabilize pressure.

(2) Preparing oxygen from the introduction port 14.

■Introducing hydrogen and combustion oxidation.

■Bost purge of oxygen.

■Pressure reduction (0.4 atm/min).

The oxidation sequence is completed as described above, and after this, the cap member 20 is removed and the fork is attached to the process tube 1.
One cycle of the high-pressure oxidation treatment process is completed by carrying it into the tube 2, mounting the quartz port 3, and carrying it out from the process tube 12.

Such a high-pressure oxidation device can generate an oxide film faster at a lower temperature than a normal-pressure oxidation device, and
The properties of the oxide film make it possible to produce a more dense film.

Here, the action during execution of the oxidation process will be explained.

The process gas is introduced through the introduction port 14, flows along the longitudinal direction of the process tube 12, and flows through the port 3.
This serves to form an oxide film on the upper semiconductor wafer 2. In order to discharge process gas and water vapor from the process tube 12, an exhaust port 15 is provided on the cap 21 side. The process gas near the discharge port 15 has a significantly lower temperature than the process gas in other areas. In particular, as shown in FIG. 1, since the heater 13 is not formed to extend to the vicinity of the discharge port 15 on the side passage, the heating by the heater 13 is not sufficient. This causes the temperature of the process gas to drop.

Then, this low-temperature process gas is applied to the semiconductor wafer 2.
If the flow backs up to the area where the gas is located, the formation of an oxide film in that area will be inhibited.

In the past, various improvements have been made to ensure the flow of process gas within the tube 12, but no measures have been taken to prevent backflow of the process gas near the discharge port 15.
The low-temperature process gas may flow back particularly into the lower region of the semiconductor wafer 2 on the side closer to the cap 21, resulting in a thin oxide film being formed in this region. Therefore, when considering the thickness of the oxide film over the entire surface of the semiconductor wafer 2, the in-plane uniformity between the lower region and the upper region was deteriorated.

Therefore, in this embodiment, in order to prevent this kind of low-temperature process gas from flowing back, a backflow prevention member 30 is disposed on the tip side of the semicircular spherical portion 23 of the cap 21. This is to prevent backflow of process gas.

That is, the backflow prevention plate 31 is connected to the process tube 12.
is formed from near the bottom of the process tube 12 to almost the center of the cross-sectional height of the process tube 12, so that even if the process gas near the discharge port 15 flows backward, it will not reach the wafer 2 mounted in the port 3. This can be reliably prevented.

The low-temperature process gas whose backflow is inhibited by the backflow prevention plate 31 does not enter further into the process tube 12, and even if the low-temperature process gas does not rise along the backflow prevention plate 31, However, since there is a flow of high temperature process gas above this, the gas is returned to the discharge port 15 along this flow.

Note that the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the gist of the present invention.

For example, in the above embodiment, the backflow prevention member 30 is removably disposed on the cap member 20 that seals the entrance D12a of the prosthesis tube 12, but the present invention is not limited thereto. Any device that can be placed between the mounting position of port 3 and the port 3 and the port 3 may be used as long as it can be placed in a manner that does not interfere with port 3. Therefore, it may be attached to the rear end of the port 3 in the carrying direction. Furthermore, it goes without saying that the shape of the backflow prevention member can be modified in various ways.

[Effect of the Invention J As explained above, according to the present invention, it is possible to prevent the low temperature process gas near the discharge port of the process tube from flowing back to the object to be processed mounted in the port. Since the entire surface of the object to be processed is surrounded by the high-temperature process gas, the in-plane uniformity of the produced film can be significantly improved.

[Brief explanation of the drawing]

Figure 1 shows an embodiment in which the present invention is applied to a high-pressure oxidation apparatus for semiconductor wafers, and is a cross-sectional view showing the internal structure of a process tube. Figures 2A and 2B are side views of a backflow prevention member. figure. 3 is a sectional view of the high-pressure oxidizer shown in FIG. 1 with the cap removed, and FIG. 4 is a sectional view of the process tube of the conventional high-pressure oxidizer. DESCRIPTION OF SYMBOLS 10... Heat treatment furnace, 12... Process tube, 12a... Carrying inlet, 13... Heater, 14... Introducing part, 15... Discharge port, 20... With cap part, 30 ... Backflow prevention member. Agent Patent Attorney Inoue - (1 other person) Figure 1 Figure 3 Figure 4 (A) ,! 2 2 CB)

Claims (3)

[Claims] (1) Load multiple objects to be processed on the port, carry this port into the process tube of the heat treatment furnace, and with this inlet port sealed with a cap, process gas is introduced from the back of the process tube. In pressurized heat treatment equipment that heat-treats objects by exhausting air from a discharge port provided on the loading port side, a backflow prevention member that prevents the process gas near the discharge port from flowing back to the back of the process tube is installed between the discharge port and the pressurized heat treatment device. A pressurized heat treatment device characterized in that it is arranged between a port and a port. (2) The pressurized heat treatment apparatus according to claim 1, wherein the backflow prevention member is attached to the front end side of the cap. (3) The backflow prevention member is formed to extend from at least the vicinity of the bottom surface of the horizontal process tube to the vicinity of the center of the cross-sectional height of the process tube.
The pressurized heat treatment apparatus according to item 1 or 2.