JP3377221B2 - Heat treatment equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus such as a thermal oxidation furnace apparatus generally used in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art Conventionally, for example, in a thermal oxidation furnace device,
In order to form an oxide film on the surface of the silicon substrate, oxygen, which is a mixture of a gas body such as oxygen and an inert gas, is introduced into a furnace core tube made of a quartz tube heated by an electric resistance heating method,
The gas body is brought into contact with a heated silicon substrate.

In this case, in order to form a highly reliable oxide film, the core tube itself which performs the oxidation reaction process must not be contaminated with particles and must be cleaned as much as possible. To be done.

Further, in order to reduce defects at the interface between the oxide film and silicon and realize the manufacture of an electrically stable semiconductor device, it is necessary to reduce the number of particles attached to the silicon substrate as much as possible.

As described above, the ultra-cleaning in the atmosphere of the heat treatment process is indispensable for realizing the ultra-miniaturized LSI.

[0006]

However, in the conventional apparatus, since the introduced gas body flows while contacting the quartz tube which is an insulator and the quartz susceptor holding the silicon substrate, the quartz tube and the quartz susceptor are charged. As a result, a large number of particles adhere, and the particles become a pollution source of the silicon substrate. Moreover, since the silicon substrate also comes into contact with the gas body at the time of loading / unloading into / from the core tube, a reaction process, and the like, particles are easily attached to the silicon substrate.

In order to solve the above-mentioned problems of the prior art, the present invention provides a heat treatment apparatus capable of forming a highly reliable oxide film on the surface of a substrate in a furnace core tube made of an insulating material and performing an oxidation reaction treatment and the like. The purpose is to do.

[0008]

The heat treatment apparatus of the present invention comprises:
In a heat treatment apparatus having a furnace core tube made of an insulating material and configured to be able to carry in and out a heated object through an opening / closing opening, a fluid introduced into the jacket by covering the outer circumference of the furnace core tube with a jacket. It is characterized in that it is provided with an irradiation means for irradiating ultraviolet light toward the. The heat treatment method according to the present invention is made of an insulating material, and has a purple color of energy of 3.4 eV or more toward a gas body introduced into a furnace core tube which is capable of carrying in and out a heated object through an opening / closing opening. Irradiate external light to select the electrified charge of the heated object in the core tube
It is characterized in that it is heat-treated while being neutralized .

The insulator constituting the core tube in the present invention is desired to be a material transparent to ultraviolet light.

[0010]

[0011]

[Function] When a gas body irradiated with ultraviolet rays is introduced into a tubular core tube made of an insulating material, the gas body is ionized by the irradiation, and the ionized positive ions and electrons are heated in the core tube. Selectively neutralizes the electrified charge of an object. Therefore, the object to be heated is not charged and particles are not attached.
Further, since the core tube is an insulator, it is possible to neutralize the ionized ions and electrons and prevent the adhesion of particles. When the light source of the light irradiating unit that irradiates the gas body contains light with energy of 3.4 eV or more, it supports the charged insulator, which constitutes the core tube, and the solid substrate carried into the core tube. It is possible to efficiently neutralize the insulator susceptor, the solid substrate and the like.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a horizontal single tube oxidation reactor apparatus showing an embodiment of the present invention. In the following description of each embodiment, the same or equivalent constituent members will be denoted by the same reference numerals. As shown in FIG. 1, the core tube main body 1 has a gas introduction part 2 formed at one end side in the tube length direction and a gas lead-out part 14 formed at the other end side, and the gas introduction part 2 is made of synthetic quartz. And an ultraviolet lamp 6 as an irradiation means is installed outside the gas introduction part 2. The material of the gas introduction part 2 may be magnesium oxide, calcium fluoride, fused silica, or the like, in addition to synthetic quartz. That is, a material that transmits at least ultraviolet rays with high efficiency may be used, and preferably a material that does not contaminate the inside of the core tube body 1 (for example, particle-free or degassing-free). A gas supply system (not shown) is connected to the upstream side of the gas introduction unit 2 via a valve 7, and the gap between the gas introduction unit 2 and the ultraviolet lamp 6 is such that ultraviolet light is a gas in the air (for example, oxygen, nitrogen, etc.). Narrower is better to avoid being absorbed by). Therefore, in order to efficiently excite the introduction gas flowing in the gas introduction portion 2 in the direction of the arrow in FIG. 1 by the ultraviolet light from the ultraviolet lamp 6, the gas introduction portion 2 is a gas that does not absorb the ultraviolet light.
It is effective to seal between the UV lamp 6 and the UV lamp 6.
That is, it is effective to use a gas in the energy region higher than the ultraviolet light absorption band of the introduction gas flowing in the gas introduction portion 2 as the sealing gas. For example, when the introduced gas is oxygen gas, nitrogen gas is effective as the sealing gas, and when the introduced gas is nitrogen gas,
Hydrogen gas is effective as the sealing gas. However, since the sealing gas absorbs ultraviolet light in the high energy region, the ultraviolet light in the high energy region is attenuated. Therefore, for example, it is effective to cover the passage of the ultraviolet light between the gas introduction unit 2 and the ultraviolet lamp 6 with a closed container and evacuate the closed container with a vacuum pump.

On the other hand, the silicon substrate 4 is placed on the quartz susceptor 5 which is a holding member in the core tube main body 1, and the heating source 3
It is designed to be heated by. As the heating source 3, a heating source composed of an electric resistance heater, an infrared lamp heater, or the like is suitable. Examples of the material of the core tube main body 1 and the susceptor 5 include synthetic quartz, fused quartz, alumina, silicon carbide, aluminum nitride, boron nitride and the like, which do not contaminate the silicon substrate 4 (for example, sodium ion-free, heavy metal). Free, degassing-free, particle-free, etc.) materials are preferred.

The silicon substrate 4 is used after it has been contacted with a dilute hydrofluoric acid solution to remove the natural oxide film, and then washed and dried with ultrapure water. After that, after being installed on the quartz susceptor 5, the lid body 11 of the opening 12 of the core tube main body 1 is opened, and the lid body 11 is brought into the core tube main body 1 by soft landing transfer and then the lid body 11 is closed. Then, the silicon substrate 4 is heated to 900 ° C. by the heating source 3. The oxygen gas introduced into the gas introduction part 2 is 2000
Set to a flow rate of cc / min. The introduced gas is irradiated with ultraviolet light by the ultraviolet lamp 6. Silicon substrate 1
After heating at 900 ° C. for 0 minutes, the silicon substrate 4 and the quartz susceptor 5 are carried out of the core tube main body 1 by the reverse procedure of the soft landing transfer. After that, the potential of the silicon substrate 4 after the oxidation reaction treatment is measured by an electrostatic potential meter, and the particles on the silicon substrate 4 are measured by, for example, a wafer surface inspection device. As an example of the actual measurement, it was obtained that the potential of the silicon substrate 4 after the reaction treatment was 5 V and the number of particles having a diameter of at least 0.5 to 5 μm was not detected.

On the other hand, without irradiating the introduced gas with the ultraviolet light from the ultraviolet lamp, the other steps are performed under the same conditions as described above, that is, the natural oxide film removal of the silicon substrate 4 by the dilute hydrofluoric acid solution, the ultrapure water cleaning, When the drying process, the installation on the quartz susceptor 5, the soft landing transfer, the heating of the silicon substrate 4 in oxygen gas at 900 ° C. for 10 minutes, and the removal by the soft landing transfer were performed under the same conditions, the potential of the silicon substrate 4 was changed. Was 2000 V, and the number of particles having a diameter of 0.5 to 5 μm on the substrate 4 was 20.

The potential of the oxide film and the silicon substrate formed by the device of this embodiment was about 50 V or less at most, and the number of particles on the oxide film was 1 or less. That is, it can be seen that the device of the present invention holds the potential of the silicon substrate 4 at 50 V or less and suppresses the adhesion of particles onto the silicon substrate 4.

FIG. 2 shows a second embodiment. In this embodiment, a jacket 8 is provided so as to cover the outside of the core tube main body 1. The jacket 8
Is provided with a fluid introducing portion 9 on one end side, and the fluid introducing portion 9
Is connected to a fluid supply via a valve 10. A fluid drain 12 is provided on the other end of the jacket 8. The fluid introducing unit 9 is made of synthetic quartz, and the ultraviolet lamp 6 is installed outside the fluid introducing unit 9. The fluid introducing section 9 is configured similarly to the gas introducing section 2 in the first embodiment.

The heating source 3 heats the silicon substrate 4 to be heated through the jacket 8 and the core tube 1.

The oxygen gas as the introduction gas flowing into the gas introduction section 2 is set to a flow rate of, for example, 2000 cc / min, but is not irradiated with ultraviolet rays while being introduced into the core tube main body 1. The fluid flowing into the fluid introducing portion 9 may be a gas body or a liquid body. For example, when nitrogen gas is used as the gas body, 1
Set the flow rate to 000 cc / min. In the case of the present embodiment, the silicon substrate 4 taken out from the core tube after the completion of the reaction treatment.
Has a potential of 40 V, and particles having a diameter of at least 0.5 to 5 μm were not detected on the silicon substrate 4.

The potential of the silicon substrate 4 is 2000 V when the fluid introducing portion 9 is not irradiated with ultraviolet rays.
Then, 25 particles having a diameter of 0.5 to 5 μm adhered to the silicon substrate 4.

FIG. 3 shows a third embodiment and relates to a vertical single tube oxidation reactor apparatus.

In this embodiment, an ultraviolet lamp 6 is installed on the outer side of the gas introduction part 2 formed in the upper part of the vertical type core tube main body 1. The structure and operation are substantially the same as those of the first embodiment except that the structure is vertical.

That is, in the case of this embodiment, the silicon substrate 4 taken out from the core tube main body 1 is the same as in the first embodiment.
The potential was 5 V, and no particles were detected on the silicon substrate 4.

FIG. 4 shows a fourth embodiment, which is substantially the same as the second embodiment except that it has a vertical structure.

FIG. 5 is a graph showing the breakdown voltage of the oxide film formed by the device of the present invention, and FIG. 6 is a graph showing the breakdown voltage of the oxide film formed by the conventional device. The horizontal axes of FIGS. 5 and 6 represent the dielectric breakdown electric field of the oxide film, and the vertical axes represent the percentage of the number of the dielectric breakdown oxide films. The thickness of the oxide film is 5n
m. N ⁺ type polycrystalline silicon is used as the gate electrode, and the gate electrode is positively applied.

The oxide film formed by the device of the present invention is 8 MV.
Dielectric breakdown does not occur with an average electric field of the oxide film of not more than / cm. On the other hand, the oxide film formed by the conventional device has a dielectric breakdown due to the average electric field of the oxide film of 8 MV / cm or less. That is, it was found that the oxide film formed by the device of the present invention has high reliability.

[0028]

EFFECTS OF THE INVENTION According to the present invention, since the charge to the object to be heated or the core tube can be easily neutralized, when it is applied to, for example, a thermal oxidation furnace treatment apparatus, it is possible to oxidize solid surfaces with excellent reliability. A film can be formed. Therefore, typically, high quality processing of a semiconductor manufacturing process can be achieved and an ultra-miniaturized semiconductor device can be realized.

[0029]

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a heat treatment apparatus according to a first embodiment.

FIG. 2 is a schematic configuration diagram of a heat treatment apparatus according to a second embodiment.

FIG. 3 is a schematic configuration diagram of a heat treatment apparatus according to a third embodiment.

FIG. 4 is a schematic configuration diagram of a heat treatment apparatus according to a fourth embodiment.

FIG. 5 is a graph showing the breakdown voltage of an oxide film formed by the device of the present invention.

FIG. 6 is a graph showing the breakdown voltage of an oxide film formed by a conventional device.

[Explanation of symbols]

1 core tube body, 2 gas introduction section, 3 heating source, 4 Silicon substrate (object to be heated), 5 susceptor, 6 UV lamp (irradiation means), 7 valves, 8 jackets, 9 jacket gas introduction section, 10 valves, 11 shutters, 12 Jacket gas exhaust, 13 openings, 14 Gas outlet.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadahiro Omi 2-1 17 of Yonegabukuro, Aoba-ku, Sendai-shi, Miyagi 301 of 72 (72) Inventor Mizuho Morita Aramaki Aoba, Aoba-ku, Sendai-shi, Miyagi (G) Tohoku University Faculty of Engineering, Department of Electronic Engineering (56) Reference JP-A-1-196813 (JP, A) JP-A 2-310924 (JP, A) JP-A 63-126231 (JP, A) JP-A 61 −232626 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/31

Claims (3)

(57) [Claims] 1. A heat treatment apparatus having a furnace core tube made of an insulating material and capable of carrying in and out an object to be heated through an opening / closing opening, wherein an outer periphery of the furnace core tube is covered with a jacket, and the inside of the jacket is covered. A heat treatment apparatus comprising an irradiation means for irradiating the fluid introduced into the chamber with ultraviolet light. 2. A violet gas having an energy of 3.4 eV or more toward a gas body introduced into a furnace core tube made of an insulating material and capable of carrying in and out a heated object through an opening / closing opening. /> By irradiating external light, the electrified charge of the heated object in the core tube is
A heat treatment method characterized by performing heat treatment while selectively neutralizing . 3. The heat treatment method according to claim 2, wherein the heat treatment is a thermal oxide film formation treatment.