JPH07297181A - Method and apparatus for thermal oxidation treatment - Google Patents

Abstract

PURPOSE:To eliminate the problem of dew condensation and to perform a thermal oxidation treatment using a treatment gas which contains misture even when a thermal oxidation treatment apparatus which is provided with an inner tube and with an outer tube is used. CONSTITUTION:A thermal oxidation treatment apparatus is provided with an inner tube 4 constituting a treatment chamber which oxidizes and treats a semiconductor substrate 2 to be treated, with a heating mechanism 1 which heats the treatment chamber and, in addition, with an outer tube 6 as an outer frame. In the thermal oxidation treatment apparatus, the temperature of the outer tube is controlled by a temperature control medium 8 such as a liquid at a boiling point of 100 deg.C or higher or a gas which is stable at 100 to 300 deg.C so as to prevent overheating and to prevent the dew condensation of the inner tube.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal oxidation treatment method and a thermal oxidation treatment apparatus. INDUSTRIAL APPLICABILITY The present invention can be used, for example, for forming a thermal oxide film as a gate oxide film of a silicon semiconductor device, and can be generally used for various thermal oxidation treatments of semiconductor substrates.

[0002]

2. Description of the Related Art An outer tube having an inner tube forming a processing chamber for oxidizing a semiconductor substrate to be processed, a heating mechanism for heating the processing chamber by light such as a halogen lamp, and an outer frame forming a furnace wall. The thermal oxidation processing device having a tube is used as a rapid thermal oxidation device (hereinafter also referred to as “RTO device”) for performing a thermal oxidation process on a semiconductor substrate wafer at high speed. Such an RTO device has the following advantages.

Since the substrate wafer is inserted at a low temperature and then the temperature is raised, oxygen entrapment is small and an ultrathin oxide film of about 2 nm can be formed with good controllability. Lamp heating is performed only when necessary, and since a high temperature heater is not provided, a clean oxide film can be formed without diffusion of metal contaminants from the heater material.

However, the conventional technique has the following problems. That is, when a thick oxide film or a highly reliable gate oxide film is formed by using the above apparatus in combination with hydrochloric acid annealing, oxidation in a wet atmosphere (for example, in a water vapor atmosphere or in an atmosphere containing oxygen or air containing water) is performed. Oxidation) is essential. However, in the conventional apparatus, dew condensation occurs inside the furnace wall when heating is not performed by a heating mechanism such as lamp heating. Therefore, there is a problem that the furnace body is damaged during heating.

The above-mentioned problems of the prior art will be described in more detail with reference to FIG.

FIG. 2 is a schematic view of a furnace portion of a conventional rapid thermal oxidation device (RTO device). In FIG. 2, reference numeral 1 is a heating mechanism, which is a halogen lamp here. With this heating mechanism 1, the semiconductor substrate 2 to be processed 2
Is heat treated. The substrate 2 to be processed is supported by a holder 3 and arranged in a processing chamber defined by an inner tube 4 (here, made of quartz). Code 5
Is a reflector that reflects the infrared rays of the lamp that is the heating mechanism 1. These are outer tubes 6 (here SUS
Are placed in a furnace defined by

The semiconductor substrate 2 (wafer) to be processed is held by the gate bubble 10 in the holder 3 in the inner tube 4.
It is inserted above and nitrogen gas is introduced from the gas inlet 14 to replace the air in the inner tube 4. After sufficient replacement, nitrogen gas is switched to oxygen gas,
The lamp that is the heating mechanism 1 is energized to emit infrared rays,
The temperature is increased by being absorbed by the semiconductor substrate 2 (wafer) to be processed, and the wafer surface is oxidized. A cooling pipe 7 is provided in the outer tube 6, and cooling water prevents overheating. In the figure, reference numeral 8'indicates introduction of cooling water and 9'indicates discharge of cooling water.

In this case, the thermal oxidation process using the conventional RTO apparatus is a dry oxidation using dry oxygen, so the oxidation rate is slow, and the gate oxidation is performed even when hydrochloric acid annealing is performed when it is used for forming a gate insulating film. It is difficult to obtain the effect of improving the film reliability. That is, while performing the hydrochloric acid annealing in the wet oxidation of the ordinary oxidation furnace has the effect of improving the reliability, there is a problem that this effect is difficult to obtain.

When performing wet oxidation in the RTO device, it is necessary to flow oxygen containing water vapor through the gas inlet 14. However, as described above, the quartz inner tube 4 is in a cold state when the lamp heating is not performed, and since the infrared ray is hardly absorbed by the quartz, the quartz inner tube 4 remains after the lamp heating 4. It keeps cold.

If a processing gas containing water vapor is flowed in this state, the water vapor will condense in the inner tube 4 made of quartz, and the temperature rise due to the heating of the lamp which is the heating mechanism 1.
This causes a stress to the inner tube 4 made of quartz when the temperature is lowered, and there is a great possibility that the quartz tube is eventually damaged.

Therefore, in the prior art, the RT is practically used.
Wet oxidation treatment using an O apparatus was impossible, and the advantage of wet oxidation could not be utilized.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art. An object of the present invention is to provide an inner tube which constitutes a processing chamber for oxidizing a semiconductor substrate to be processed, and the processing chamber. Even when using a thermal oxidation treatment device having a heating mechanism for heating the outer frame that further constitutes an outer frame, there is no problem of dew condensation, and a thermal oxidation treatment using a treatment gas containing water is also possible. A thermal oxidation treatment method and a thermal oxidation treatment device are provided.

[0013]

The invention according to claim 1 of the present application comprises an inner tube constituting a processing chamber for oxidizing a semiconductor substrate to be processed, a heating mechanism for heating the processing chamber, and an outer frame. Is a thermal oxidation treatment method using a thermal oxidation treatment apparatus having an outer tube, wherein the temperature of the outer tube is controlled by a temperature control medium to prevent heating and dew condensation on the inner tube. A method of thermally oxidizing a semiconductor substrate, which achieves the above object.

In the invention of claim 2 of the present application, the temperature control medium is a liquid having a boiling point of more than 100 ° C., or 100 to 30.
The method for thermal oxidation treatment of a semiconductor substrate according to claim 1, wherein the method is a gas that is stable at 0 ° C., thereby achieving the above object.

According to a third aspect of the present invention, there is provided an outer tube which comprises an inner tube forming a processing chamber for oxidizing a semiconductor substrate to be processed, a heating mechanism for heating the processing chamber, and further an outer frame. A thermal oxidation treatment apparatus having, wherein a pipe for flowing a temperature control medium is arranged in the outer tube, and the temperature of the temperature control medium is controlled by a temperature control unit to control the temperature of the outer tube, thereby preventing overheating. And a thermal oxidation treatment device for a semiconductor substrate, characterized in that the inner tube is configured to prevent dew condensation.

According to the invention of claim 4 of the present application, the temperature control medium is a liquid having a boiling point of more than 100 ° C., or 100 to 30.
A thermal oxidation treatment apparatus for a semiconductor substrate according to claim 3, wherein the apparatus is a gas stable at 0 ° C., thereby achieving the above object.

[0017]

The present invention provides a thermal oxidation treatment apparatus having an inner tube which constitutes a treatment chamber for thermally oxidizing a semiconductor substrate to be treated, a heating mechanism for heating the treatment chamber, and an outer tube which constitutes an outer frame. For example, the boiling point is 1
Technology for preventing overheating and preventing condensation on the inner tube by controlling the temperature of the outer tube with a temperature control medium that uses a liquid that exceeds 00 ° C or a refrigerant that is a stable gas at 100 to 300 ° C. Therefore, the prevention of overheating and the prevention of dew condensation can be achieved at the same time, and the prevention of dew condensation can be achieved by adopting the structure of the conventional overheating prevention as it is, which is simple and advantageous. Therefore, according to the present invention, regarding the heat treatment of the semiconductor substrate to be processed, RT
With the O device and the like, thermal oxidation treatment in a wet atmosphere, which has been impossible in the past, is made possible by an easy configuration.

In the present invention, it is not necessary to use a structure in which a multiple pipe made of, for example, quartz is used, and in particular, a heat generator is provided and heated by a heating source to prevent dew condensation. A special structure is not necessary, and it is an advantage that a heat treatment technique that prevents dew condensation can be provided by an excellent and simple structure.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. However, it should be understood that the present invention is not limited to the illustrated embodiments.

Example 1 In this example, the present invention is applied when a semiconductor substrate, especially a Si substrate, is subjected to thermal oxidation treatment in a rapid thermal oxidation device (RTO device) having a heating mechanism by light such as a halogen lamp. A high boiling point liquid having a boiling point of 100 ° C. or higher is used as a refrigerant of a cooling mechanism for preventing overheating of the furnace body, and the temperature of this refrigerant is controlled to keep the inner wall of the furnace body at 100 ° C. or higher. It is a thing.

The thermal oxidation treatment apparatus of this embodiment is shown in FIG. As shown in FIG. 1, the thermal oxidation treatment apparatus of the present embodiment,
An inner tube 4 which constitutes a processing chamber for oxidizing a semiconductor substrate 2 to be processed, and a heating mechanism 1 for heating the processing chamber.
(In this case, a lamp) and further has an outer tube that constitutes an outer frame. In this case, the temperature of the outer tube 6 is controlled by a temperature control medium to prevent overheating and dew condensation of the inner tube. And Further, in this thermal oxidation treatment apparatus, a pipe 7 for flowing a temperature control medium is arranged in the outer tube 6 (in FIG. 1, reference numeral 12 indicates introduction of the temperature control medium, and reference numeral 13 indicates discharge of the temperature control medium). The temperature control unit 11 controls the temperature of the temperature control medium to control the temperature of the outer tube 6, thereby preventing overheating and preventing dew condensation on the inner tube 4.

In this embodiment, as the temperature control medium, a liquid which is a refrigerant for preventing overheating and has a boiling point of more than 100 ° C. is used. In FIG. 1, reference numeral 8 indicates the introduction of the temperature control medium into the temperature control unit 11, and reference numeral 9 indicates the discharge of the temperature control medium from the temperature control unit 11.

In this embodiment, since the dew condensation is prevented as described above, it is possible to perform wet oxidation by using O ₂ containing H ₂ O which is a wet oxidizing gas at the time of thermal oxidation. .

More specifically, in this embodiment, the SU
In order to prevent the furnace body from overheating due to the heat generated by the halogen lamp that is the heating mechanism 1 inside the S outer tube 6,
A pipe 7 through which a liquid having a boiling point of at least 100 ° C. is passed as a refrigerant is arranged. This refrigerant is the temperature control medium. Here, specifically, the temperature control medium (refrigerant) is made of silicon oil having a boiling point of more than 100 ° C.

In the present embodiment, the temperature control unit 11 controls the temperature of the temperature control medium (refrigerant) so that the inner wall temperature of the quartz inner tube 4 is controlled to 100 ° C. or higher.

As a result, even if the wet oxidation atmosphere or the thermal oxidation is performed, dew does not condense on the furnace wall, and damage to the furnace body at the time of temperature rise, which is a concern in the dewed state, can be prevented. Therefore, in this embodiment, wet oxidation in an RTO device, which was impossible in the past, was possible.

In the present embodiment, the temperature sensor 15 is provided on the outer wall of the quartz inner tube 6, and the temperature is fed back to the temperature control unit 11 based on the temperature sensor 15, so that temperature control and dew condensation prevention can be performed more accurately.

Further, between the outer wall of the quartz inner tube 4 and the SUS outer tube 6 (excluding between the outer wall of the quartz inner tube 4 and the lamp 1), heat conduction of lead or the like is good, and good thermal contact can be achieved. The presence of a substance can also improve the dew condensation prevention performance.

Further, as the heating mechanism 1, instead of the lamp heating, an oxidizing device using laser irradiation such as an excimer laser can be used so as to perform wet oxidation.

In this example, the thermal oxidation treatment was specifically carried out as follows. That is, first, the substrate to be processed 2 (wafer)
In the same manner as the conventional technique, the gate bubble 10 inserts the nitrogen gas into the holder 3 in the inner tube 4, introduces nitrogen gas from the gas introduction port 14, and replaces the air in the inner tube 4. After being sufficiently replaced, the nitrogen gas is switched to a mixed gas of oxygen gas and water vapor in the present embodiment, the lamp which is the heating mechanism 1 is energized and infrared rays are radiated (reference numeral 5 is a reflection plate), Processed semiconductor substrate 2
The (wafer) is heated and the surface of the wafer is oxidized. At this time, the temperature control medium passing through the pipe 7 of the outer tube 6 prevents overheating and also prevents dew condensation even when the treatment is performed in a wet atmosphere.

According to this embodiment, the following advantages are brought about. Despite the use of the RTO device, a high oxidation rate 10 to 20 times higher than that of the conventional dry oxidation can be obtained.
A thick oxide film such as a COS oxide film can be formed with good productivity.

If wet oxidation is combined with hydrochloric acid annealing, a highly reliable gate oxide film can be formed. (This is the effect proved by the combination of diffusion furnace oxidation and hydrochloric acid annealing.)

The advantages of RTO oxidation, that is, the controllability of ultra-thin oxidation and the formation with a clean oxide film can be fully exhibited.

By combining the above characteristics, a gate oxide film of a 0.1 μm class MOS transistor, for example, can be formed with high reliability and controllability.

Example 2 In this example, a stable gas at about 100 to 300 ° C. was used in place of the liquid as the refrigerant which is the temperature control medium. Also in this example, the same effect as that of Example 1 was obtained.

In this embodiment, the thermal oxidation treatment apparatus of Embodiment 1 (FIG. 1) can be used as the apparatus, but in the case of this embodiment, the outer wall of the quartz inner tube 4 and the SUS outer tube 6 are formed. The entire space between them may be used as a cooling pipe through which the gas passes.

[0037]

According to the present invention, a heat treatment is provided which includes an inner tube forming a processing chamber for oxidizing a semiconductor substrate to be processed, a heating mechanism for heating the processing chamber, and an outer tube forming an outer frame. Even in the case of using the oxidation treatment device, there was no problem of dew condensation, and a thermal oxidation treatment method capable of performing a thermal oxidation treatment using a treatment gas containing water could be provided. Further, a thermal oxidation treatment device capable of such treatment can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a thermal oxidation treatment apparatus according to a first embodiment.

FIG. 2 is a configuration diagram showing a conventional thermal oxidation treatment device. 1 heating mechanism (lamp such as halogen lamp) 2 processed semiconductor substrate (Si substrate) 3 (substrate) holder 4 (quartz) inner tube 5 reflector 6 (SUS) outer tube 7 (cooling) pipe 8 to temperature control unit Temperature control medium (refrigerant) introduction 9 Temperature control medium (refrigerant) discharge from the temperature control unit 10 Gate valve 11 Temperature control unit 12 Temperature control medium (refrigerant) introduction into the pipe 13 Temperature control medium (refrigerant) discharge from the pipe

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01L 21/31 21/324 D

Claims (4)

[Claims] 1. A thermal oxidation treatment apparatus having an inner tube constituting a treatment chamber for thermally oxidizing a semiconductor substrate to be treated, a heating mechanism for heating the treatment chamber, and further having an outer tube constituting an outer frame is used. A thermal oxidation treatment method for a semiconductor substrate, characterized in that the temperature of the outer tube is controlled by a temperature control medium to prevent overheating and dew condensation on the inner tube. 2. The method for thermal oxidation treatment of a semiconductor substrate according to claim 1, wherein the temperature control medium is a liquid having a boiling point of higher than 100 ° C. or a gas stable at 100 to 300 ° C. 3. A thermal oxidation treatment apparatus comprising an inner tube constituting a treatment chamber for oxidizing a semiconductor substrate to be treated, a heating mechanism for heating the treatment chamber, and an outer tube constituting an outer frame. A pipe for flowing a temperature control medium is arranged in the outer tube, and the temperature of the temperature control medium is controlled by a temperature control unit to control the temperature of the outer tube, thereby preventing overheating and preventing dew condensation on the inner tube. A thermal oxidation treatment device for a semiconductor substrate having a configuration. 4. The thermal oxidation treatment apparatus for a semiconductor substrate according to claim 3, wherein the temperature control medium is a liquid having a boiling point of higher than 100 ° C. or a gas stable at 100 to 300 ° C.