JPH0778779A - Radiation heat preventing plate and use thereof - Google Patents

Abstract

PURPOSE:To provide a radiation heat preventing plate which is so formed in structure as to meet requirements with a less number of sheets and the use thereof, wherein the radiation heat preventing plate is used in a, vacuum processing device possessed of an inner space composed of temperature regions continuously arranged in one direction and provided between the adjacent temperature regions so as to keep a low-tempreature region at a constant temperature throughout it preventing radiant heat from being transmitted from a high- temperature region to a low-temperature region arranged adjacent to each other. CONSTITUTION:A radiant heat preventing plate has such a structure that one side or both sides of a metal plate 103 or a metal foil or metal film (hereinafter referred to as metal) is coated with inorganic thermal insulating material. Single crystal Al2O3 101 which can be mirror-finished and bonded to metal by pressure or quartz which can be used as melt coating. The radiant heat preventing plate is used in such a manner that the plates are provided between adjacent temperature regions and increased in number by one for every temperature difference of 25 deg.C between the adjacent regions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low pressure CVD apparatus for introducing a thin film material gas into a container whose internal space is kept at a high temperature in a reduced pressure state to form a thin film on a substrate surface in the container, or an oxidizing gas. In a decompression treatment device such as an oxidation diffusion device that introduces a reduced pressure state to permeate into the substrate mother body and oxidize the entire substrate, particularly in a container in which the internal space is formed of a plurality of temperature regions that are continuously adjacent in one direction. When the substrate is processed by a decompression processing device that arranges the substrate to be processed in a temperature region other than the highest temperature region and introduces the processing gas into the internal space under reduced pressure to process the substrate. The substrate to be processed is arranged on the side of a higher temperature temperature region adjacent to the temperature region to which it belongs, and radiant heat from the high temperature temperature region to the substrate is prevented so as to keep the substrate at the temperature of the temperature region to which it belongs. Radiant heat prevention plate About.

[0002]

2. Description of the Related Art Conventionally, as a low pressure CVD apparatus or an oxidation diffusion apparatus for processing a substrate to be processed under reduced pressure, generally, FIG.
The thing of the composition of is known. This apparatus is composed of a heater 1 which is formed in a cylindrical shape by using a heating element such as a nichrome wire, and a cylindrical external reaction which is surrounded by the heater 1 and which is made of quartz and whose upper end surface is covered with a dome-shaped lid plate. It is configured as a one-stage furnace type apparatus having a tube 2, an internal reaction tube 3 made of quartz, which is arranged coaxially with the external reaction tube 2, and a processing gas introduction tube 4, as main components.

By using this apparatus, for example, S
iO₂When forming a film, set the substrate to be processed at an appropriate interval.
The boats 5 which are kept and stacked in a stacked state
The heat inside the device is inserted into the bottom of the boat 5 as well as inside.
Stack of SiC plates to prevent the metal from escaping downward
The inner reaction tube 3 and the lower end surface of the inner reaction tube 3 is a base flange.
After being closed at 6, heating current is supplied to the heater 1,
When the internal temperature rises to the specified temperature, process gas is introduced
As a processing gas from the pipe 4, for example, N₂For gas bubbling
TEOS (Tetra Ethyl Ortho Sili) in a more vapor state
cate, SiO₂Internal reaction of liquid organic material including membrane components)
Introduced inside the tube 3 and on the substrate SiO ₂Formed a film
After that, the cylindrical space between the inner reaction tube 3 and the outer reaction tube 2 is opened.
It passes through and is discharged to the outside.

In the one-stage furnace type apparatus configured as described above, it is necessary to change the temperature in the furnace for the annealing treatment after film formation. After the taps of the heater 1 are switched, the temperature in the furnace is changed to the annealing treatment. It took a long time to reach a temperature suitable for, and there was a problem in productivity as an apparatus. For this reason, development of a two-stage furnace type apparatus as shown in FIG. 2 is under way. In addition, in FIG. 3, as a conventional general decompression processing apparatus,
The vertical type reaction tube is shown, but the horizontal type reaction tube is often used.

FIG. 2 shows an example of a two-stage furnace type apparatus configuration. A reaction tube 8 for inserting a boat 7 in which substrates to be processed are stacked in a stacked state is made long in the axial direction, and a heater is also provided. It has a two-stage structure for annealing, film formation or oxidation diffusion (hereinafter referred to as processing) in the axial direction. In the device shown,
The first heater 10 that is an annealing heater is arranged on the inner side of the reaction tube 8, and the second heater 11 that is a processing heater is arranged on the boat insertion port side of the reaction tube 8, and the inner space of the reaction tube 8 is
It consists of a high temperature region on the inner side of the reaction tube and a low temperature region on the boat insertion port side of the reaction tube. The reaction tube 8 is surrounded by a first dust-proof chamber 12 made of quartz in a high temperature region on the back side, and a second dust-proof chamber 13 made of quartz in a low temperature region on the boat insertion port side. The dust is prevented from adhering to the surface and the incidence rate of radiant heat on each temperature region is prevented from decreasing. Further, a heat reflection plate 14 is provided between the first dustproof chamber 12 and the second dustproof chamber 13 in a ring shape so as to surround the reaction tube 8 to thermally isolate both temperature regions and to process the substrate. Sometimes all substrates can be processed in a low temperature soaking zone. A heat shield mechanism 9 made of a SiC plate is inserted into the reaction tube boat insertion opening side of the boat 7 inserted into the quartz tube 8. After the insertion, the internal space of the reaction tube 8 has a base flange 15 To be closed. After closing, the processing gas is introduced from a processing gas introduction port (not shown) provided on the boat insertion port side of the reaction tube 8 and discharged to the outside through the exhaust pipe 8a on the inner side of the reaction tube 8. In the figure, reference numeral 16 is a control thermocouple and 17 is a temperature measuring thermocouple.

[0006]

Thus, if the depressurization processing apparatus is of a two-stage furnace system, the boat is immediately raised to the high temperature region on the inner side of the reaction tube and the annealing process is started after the substrate processing. While it is possible to improve the productivity of the device remarkably, the radiant heat from the high temperature region causes the heat reflection plate (14) to be provided between the two temperature regions, so that it is located on the high temperature region side. As a result, the substrate temperature rises, and the film formation rate becomes non-uniform in the stacking direction of the substrates. Therefore, even if an SiC plate is arranged on the high temperature region side of the deposition target substrates stacked in a stacked state to suppress the temperature rise due to radiant heat, for example, a heater that can be used at 800 to 950 ° C. is used for the first heater 10. Then, a heater that can be used at 500 to 700 ° C. is used as the second heater 11, and the temperature in the high temperature range is set to 900.
When the film is formed using five SiC plates with a thickness of about 3 mm at a temperature of 700 ° C in the low temperature region of 700 ° C, the unevenness of the film formation rate is still insufficiently improved to ± 10%, and 25
There was a problem that only a few of them could be applied to the device.

An object of the present invention is to arrange a substrate to be processed in a temperature region other than the temperature region where the temperature is the highest in a container having a plurality of temperature regions whose inner spaces are adjacent to each other continuously in one direction and for processing. When a substrate is processed by a decompression processing apparatus that introduces a gas into the internal space in a decompressed state to process the substrate, the substrate is arranged on the side of a higher temperature temperature region adjacent to the temperature region to which the substrate belongs. (EN) A structure of a radiant heat preventive plate capable of preventing radiant heat from the high temperature temperature region and holding the substrate at the temperature of the temperature region to which the substrate belongs, and a method of using the same.

[0008]

In order to solve the above-mentioned problems, in the present invention, the radiant heat preventive plate is a metal plate or a metal foil or a metal film, and one or both surfaces thereof are made of an inorganic heat insulating material. It is formed in a structure covered with a coating. Here, it is very suitable to use single crystal Al ₂ O _{3 as} the inorganic heat insulating material.

Alternatively, the inorganic heat insulating material may be quartz. Then, as a method of using the radiant heat preventive plate having the above structure so as to maintain the temperature of the temperature region to which the substrate to be processed belongs, the temperature of the temperature region to which the substrate to be processed belongs and the side on which the radiant heat preventive plate is arranged are It is assumed that the radiant heat preventive plate is increased by one for each difference of about 25 ° C. from the temperature in the high temperature temperature region.

[0010]

The present invention focuses on the fact that a metal plate or a metal foil or a metal film having a mirror surface as a light reflecting surface has the highest radiation heat preventing function as a radiation heat preventing plate. However, the processing gas is introduced into the furnace where the radiant heat prevention plate is arranged, and if the surface of the metal plate or the metal foil or the metal film is simply made to be a mirror surface, the metal and the processing gas react with each other so that a mirror surface state is obtained. Can not hold for a long time. Therefore,
The best radiant heat prevention function is maintained for a long period of time by covering the mirror surface in a coating state so that the processing gas does not come into contact with the mirror surface with an inorganic heat insulating material that does not change the material thermally and does not react with the processing gas. It is possible to obtain a radiant heat prevention plate that can be used. In this case, the inorganic heat insulating material may be transparent or non-transparent.

A method of using an organic adhesive when the mirror surface is covered with an inorganic heat insulating material is also conceivable. In this case, there is no gap between the mirror surface of the metal surface and the inorganic heat insulating material, and the mirror surface is covered with the inorganic heat insulating material in a coating state. The use of organic adhesives is not preferable from the standpoints of long-term retention of mirror surface condition and maintenance of device performance, because there is a possibility that the material during use may change and the adhesive components may diffuse into the high temperature atmosphere, which may adversely affect the substrate during processing. .

Therefore, as an inorganic heat insulating material for covering the metal plate or the metal foil or the metal film in a coated state,
In the present invention, attention is paid to single crystal Al ₂ O ₃ (commonly called sapphire). This has the property that single crystal Al ₂ O ₃ can have a mirror-finished surface, which allows pressure-bonding in vacuum with a metal plate or metal foil or metal film having a mirror-finished surface. Because it will be possible. Since pressure bonding in vacuum is due to intermolecular attractive force between both mirror surfaces, it is extremely difficult to contact the processing gas with the bonding surface.

In terms of handling, the radiant heat prevention plate is preferably one having rigidity and toughness when it is frequently attached to and detached from the upper part of the boat (on the high temperature region side of the boat). The metal covered with Al ₂ O ₃ is most preferably a metal plate. Further, even if quartz is used as the inorganic heat insulating material, it is possible to obtain a high-performance radiant heat preventive plate similar to that of single crystal Al ₂ O ₃ . At this time, the quartz is melted and the mirror surface of the metal plate or metal foil or metal film surface is coated in vacuum. In this case, since the working process involves thermal work, the working process is slightly complicated, but single crystal Al ₂ O ₃
Compared with, there is an advantage that the material can be easily obtained.

The radiant heat preventive plate having the above structure has a very high radiant heat preventive function. When the temperature of the high temperature region by the first heater 10 in FIG. 2 is 950 ° C. and the temperature of the low temperature region by the second heater 11 is 700 ° C. When the radiation heat prevention plate is not used, the temperature on the high temperature side of the film formation substrate is about 75.
The radiant heat from the high temperature region adversely affected the uniformity of the film thickness in the substrate stacking direction, but the temperature was about 725 ° C when one radiant heat preventive plate having the above structure was inserted, and about 700 when the two were inserted. The temperature was about the same as the temperature in the low temperature region. From this, the radiant heat preventive plate having the above structure has a temperature difference of about 25 degrees between the temperature in the high temperature region and the temperature in the low temperature region.
By increasing the number of substrates to be used one by one for each ° C, it is possible to perform processing while maintaining all the substrates to be processed belonging to the low temperature region at the temperature of the low temperature region.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a radiant heat preventive plate structure according to the present invention.
An example is shown. This radiant heat prevention plate is a
It is intended for processing substrates and is a disk-shaped single crystal Al.₂O₃
2 sheets (diameter 167 mm, thickness 0.5 mm) 101,
Ring-shaped single crystal Al₂O ₃(Outer diameter 167 mm, inner diameter 1
50 mm, thickness 0.5 mm) 102 and one disc-shaped
Tungsten (diameter 150 mm, thickness 0.5 mm) 10
Using 3 and one, press-bonded in vacuum as shown
Of. This radiant heat prevention plate has a two-stage structure as shown in FIG.
Used for furnace type equipment₂Deposit a film
Experiments were carried out on the radiant heat prevention effect of the radiant heat preventive plate at the time of heating.
The temperature of the high temperature region inside the reaction tube 8 is 900 ° C.
The temperature of the low temperature region to be placed is 700 ° C.
iO₂The processing gas for forming the film is N 2₂Gas bab
Using TEOS vaporized by a ring, this is 100
Introduced into the reaction tube 8 at a flow rate of [SCCM],
Exhaust so that the pressure in the reaction tube 8 becomes 0.3 [Torr].
And the radiant heat prevention plate is mounted on the boat 7 to be treated.
Two sheets were used at a position 100 on the high temperature region side of the substrate group. This
As a result, the film formation speed can be made uniform in the boat, and the substrate
The uniformity was within ± 5%.

[0016]

In the present invention, since the radiant heat preventive plate is formed in the above structure and used in the above method, the effects described below can be obtained. According to the first aspect of the present invention, the metal surface finished as a mirror surface does not react with the processing gas, the initial mirror surface state can be maintained for a long time, and the maximum radiant heat prevention function of the mirror surface can be made permanent. . Further, since the coating is carried out with the inorganic heat insulating material, there is no risk of the atmospheric gas being contaminated during the processing, and a good processing result can always be obtained.

According to the radiant heat preventive plate of the second aspect, it is possible to perform pressure contact bonding between the inorganic heat insulating material and the metal.
As the metal plate covered with the inorganic heat insulating material, it is possible to easily obtain the radiant heat preventive plate having the effect of the radiant heat preventive plate structure according to claim 1 and having rigidity and toughness and easy to handle. In the radiant heat preventive plate of the third aspect, it is possible to obtain the radiant heat preventive plate having the same effect as in the first and second aspects by using easily available quartz.

According to the method of claim 4, since the radiant heat prevention effect of the radiant heat preventive plate according to the structure of the present invention is as large as about 25 ° C. per sheet, the radiant heat preventive plate is arranged without any other method. Only by the method, the desired radiant heat prevention effect can be obtained with a small number of sheets used.

[Brief description of drawings]

1A and 1B show an embodiment of a radiant heat prevention plate structure according to the present invention, in which FIG. 1A is a cross-sectional view and FIG. 1B is a plan view.

FIG. 2 is a vertical cross-sectional view showing an example of the configuration of a decompression processing apparatus to which a radiant heat prevention plate according to the present invention is installed.

FIG. 3 is a vertical cross-sectional view showing an example of the configuration of a conventional general decompression processing apparatus for explaining the history of development of the decompression processing apparatus shown in FIG.

[Explanation of symbols]

1 Heater 2 External reaction tube 3 Internal reaction tube 4 Processing gas introduction tube 5 Boat 7 Boat 8 Reaction tube 10 First heater 11 Second heater 14 Heat reflection plate 100 Radiant heat prevention plate installation position 101 Single crystal Al ₂ O ₃ plate 102 Single Crystal Al ₂ O ₃ ring 103 Metal plate

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01L 21/205 21/31

Claims (4)

[Claims] 1. A substrate to be processed is arranged in a temperature region other than a temperature region where the temperature is the highest in a container having a plurality of temperature regions whose inner spaces are adjacent to each other in one direction, and a processing gas is contained inside the container. When a substrate is processed by a decompression processing device that introduces the substrate into a space in a reduced pressure state and processes the substrate, the substrate to be processed is placed on the side of a higher temperature temperature region adjacent to the temperature region to which the substrate belongs In a radiant heat prevention plate that prevents radiant heat from the temperature range and keeps the substrate at the temperature of the temperature range to which it belongs, one or both surfaces of the metal plate or metal foil or metal film is an inorganic heat insulating material. A radiant heat prevention plate characterized by being covered with a coating state. 2. The radiant heat preventive plate according to claim 1, wherein the inorganic heat insulating material covering one or both surfaces of the metal plate, the metal foil or the metal film in a coated state is a single crystal Al ₂ O. A radiant heat prevention plate characterized by having ₃ . 3. The radiant heat preventive plate according to claim 1, wherein the inorganic heat insulating material for covering one surface or both surfaces of the metal plate, the metal foil or the metal film in a coated state is quartz. Characteristic radiant heat prevention plate. 4. A method of using the radiant heat preventive plate according to claim 1 so as to maintain the temperature of a temperature region to which the substrate to be processed belongs, wherein the temperature of the temperature region to which the substrate to be processed belongs A method for using the radiant heat preventive plate, characterized in that the radiant heat preventive plate is increased by one every about 25 ° C. from the temperature in the high temperature temperature region on the side where the radiant heat preventive plate is arranged.