WO2004088734A1

WO2004088734A1 - Method of heat treatment and heat treatment apparatus

Info

Publication number: WO2004088734A1
Application number: PCT/JP2004/003152
Authority: WO
Inventors: Yasushi Asaoka; Tadaaki Kaneko; Naokatsu Sano; Hiroshi Kawai; Tomohiro Iwazaki; Seiji Yamaguchi; Hiroyuki Matsumoto; Toshiyuki Kouno
Original assignee: Kwansei Gakuin Educational Foundation; The New Industry Research Organization; Iwasaki Electric Co., Ltd.
Priority date: 2003-03-10
Filing date: 2004-03-10
Publication date: 2004-10-14

Abstract

A method of heat treatment suitable for heat treatment in a process for liquid phase epitaxial growth of single-crystal silicon carbide, the process comprising superimposing a single-crystal silicon carbide substrate as seed crystal and a polycrystalline silicon carbide substrate upon each other, disposing the laminate in a closed vessel, performing high-temperature heat treatment and, during the heat treatment, interposing an extremely thin metallic silicon melt between the single-crystal silicon carbide substrate and the polycrystalline silicon carbide substrate so as to effect a liquid phase epitaxial growth of single-crystal silicon carbide on the single-crystal silicon carbide substrate. In the heat treatment method, the closed vessel is heated in advance to about 800°C or above in a preheating chamber of 10-5 Pa or below pressure, with the internal pressure of the closed vessel simultaneously reduced to 10-5 Pa or below, and moved into and disposed in a heating chamber of inert gas atmosphere preheated to given temperature within the range of about 1400 to 2300°C and having its pressure reduced to 10-2 Pa or below vacuum or given degree, so that the single-crystal silicon carbide substrate and the polycrystalline silicon carbide substrate are heated within a short time to given temperature within the range of about 1400 to 2300°C, thereby obtaining a single-crystal silicon carbide free of microcrystalline grain boundary whose surface micropipe defect density is 1/cm2 or less. Further, there is provided a heat treatment apparatus for use in the performing of the heat treatment method.

Description

Specification

Heat treatment method and heat treatment equipment

Technical field

TECHNICAL FIELD The present invention relates to a heat treatment method in a liquid phase epitaxial growth method of single crystal silicon carbide and a heat treatment apparatus suitable for carrying out the method. Background art

Conventionally, a heat treatment apparatus used in a semiconductor manufacturing process includes a heat treatment apparatus that heat-treats an object at a high speed in order to reduce the heat history of the object and prevent the occurrence of slip (Patent Document 1: Japanese Unexamined Patent Publication No. Hei 8-70008), a heat treatment apparatus capable of forming a high vacuum in a short time and performing epitaxy growth at a low pressure (see Patent Document 2: Japanese Patent Laid-Open Publication No. 111-260738), and the like are reported. ing.

These heat treatment devices used in the conventional semiconductor manufacturing process are mainly used for epitaxial growth of silicon carbide (hereinafter referred to as SiC). For this reason, the operating temperature of the heat treatment apparatus described in Patent Document 1 is, for example, 950 ° C. in the high-temperature section, and the heat treatment apparatus described in Patent Document 2 is 800 ° C. to 900 ° C. I have.

However, in recent years, it is not only excellent in heat resistance and mechanical strength but also resistant to radiation, and it is easy to control the valence electrons of electrons and holes by adding impurities. (By the way, about 3.3 OeV for 6H-type SiC single crystal and 3.3 eV for 4H-type SiC single crystal), silicon (hereafter referred to as Si) and garymhi Single-crystal silicon carbide, which can realize high temperature, high frequency, withstand voltage and environmental resistance that cannot be realized with existing semiconductor materials such as element (hereinafter referred to as GaAs) As a semiconductor material for power devices and high-frequency devices, And is expected.

Hexagonal SiC has a lattice constant close to that of gallium nitride (GaN), and is expected to serve as a GaN substrate.

As described in Patent Document 3: Japanese Patent Application Laid-Open No. 2001-158695, this type of single crystal S i C has a seed crystal fixedly arranged on a low temperature side in a rutupo and a raw material S i C on a high temperature side. By placing the powder containing Si and heating the crucible to a high temperature of 1450 ° C to 2400 ° C in an inert atmosphere, the powder containing Si is sublimated and re-formed on the surface of the seed crystal on the low-temperature side. Some are formed by a sublimation recrystallization method (improved Lely method) in which a single crystal is grown by crystallization.

In addition, as described in Patent Document 4: Japanese Patent Application Laid-Open No. 11-315000, a SiC single crystal substrate and a plate material composed of Si atoms and C atoms are parallel to each other with a small gap. Heat treatment in an inert gas atmosphere at atmospheric pressure or lower and in a SiC saturated vapor atmosphere with a temperature gradient so that the side of the SiC single crystal substrate is also at a low temperature. Sublimates and recrystallizes Si atoms and C atoms in the minute gap. Some deposit a single crystal on a single crystal substrate.

In addition, as described in Patent Document 5: Japanese Patent Application Laid-Open No. 10-509943, after forming a first epitaxy layer on a SiC single crystal by a liquid phase epitaxy method, a CVD method is used. In some cases, a second epitaxial layer is formed on the surface to remove micropipe defects.

However, as described in Patent Documents 3 to 5, it is necessary to perform heat treatment at a high temperature of 1450 ° C. to 2400 ° C. as described in Patent Documents 3 to 5. For this reason, it is difficult to form a single crystal SiC in a conventional heat treatment apparatus as described in Patent Document 1 or Patent Document 2. In addition, for example, in the case of the sublimation recrystallization method described in Patent Document 3, the growth rate is very fast, at several 100 μππ / ΐιr, but at the time of sublimation, the SiC powder gradually becomes Si, _{_{S i C 2, S i 2}} C is decomposed and vaporized, and further reacts with over part of the crucible. For this reason, the type of gas that reaches the surface of the seed crystal varies depending on temperature changes, and it is technically very difficult to control these partial pressures stoichiometrically accurately. In addition, impurities are easily mixed in, and crystal defects and cracks in a mic opening are easily generated due to strains caused by the mixed impurities and heat. However, there is a problem that a single crystal S i C stable in performance and quality cannot be obtained.

On the other hand, in the case of the liquid-phase epitaxy method (hereinafter referred to as LPE method) described in Patent Documents 4 and 5, the occurrence of micropipe defects and crystal defects such as those observed in the sublimation recrystallization method is small. As a result, a single crystal SiC superior in quality to that produced by the sublimation recrystallization method can be obtained. On the other hand, since the growth process is controlled by the solubility of C in the Si melt, the growth rate is very slow at 10 mZhr or less, and the productivity of single crystal SiC is low. The temperature of the liquid phase in the equipment must be precisely controlled. In addition, the process becomes complicated, and the manufacturing cost of single-crystal SiC becomes extremely expensive. Disclosure of the invention

The present invention has been made in view of the above problems, and provides a heat treatment method suitable for forming a new material, for example, a next-generation single crystal SiC, and a heat treatment apparatus suitable for performing the heat treatment method. The purpose is to:

The heat treatment method of the present invention mainly has the following several features to achieve the above object. In the present invention, the following main features alone, Alternatively, they are provided in appropriate combinations. And the heat treatment apparatus of the present invention is an apparatus suitable for performing the heat treatment method of the present invention.

In the heat treatment method according to the present invention, the object to be treated is heated to about 800 ° C. or more in a short time.

A heating chamber for heating to a predetermined temperature in a range of not more than 200 ° C., preferably in a range of not less than about 1200 ° C. and not more than 230 ° C .; A heat treatment apparatus comprising: a front chamber provided with a moving means for moving an object to be processed in the chamber; and a preheating chamber connected to the front chamber and heating the object to be processed to a predetermined temperature in advance. In a heat treatment method, the object is preliminarily heated to about 800 ° C. or more in a vacuum preheating chamber having a pressure of about 10 to ² Pa or less, preferably about 10 to ⁵ Pa or less. After that, it is heated to a predetermined temperature in the range of about 800 ° C or more and 260 ° C or less, preferably in the range of about 1200 ° C or more and 230 ° C or less. pressure of about 1 0- ² P a less preferably about 1 0- ⁵ P a hereinafter the vacuum, or pre-pressure of about 1 0- ² P a or less, preferably to about 1 0- ⁵ P a hereinafter the vacuum After reaching the inert gas By moving to the heating chamber under the rare gas atmosphere, the object to be treated is quickly heated to a temperature in the range of about 800 ° C. to 260 ° C., preferably about 1200 ° C. It is characterized in that it is heated to a predetermined temperature within the range of not less than ° C and not more than 230 ° C.

According to the heat treatment method of the present invention, the time is in the range of about 800 ° C. to 260 ° C., preferably in the range of about 120 ° C. to 230 ° C. Since it can be heated to a predetermined temperature within the furnace, there is a possibility that a new material that cannot be obtained with the conventional heat treatment apparatus can be created.

The heat treatment method described above is suitable as a heat treatment method in a liquid phase epitaxial growth method of single crystal SiC.

Specifically, the heat treatment method in the liquid-phase epitaxial growth method of single-crystal silicon carbide of the present invention includes a method in which a single-crystal silicon carbide substrate serving as a seed crystal and a polycrystalline silicon carbide substrate are stacked and placed in a closed container. Installation and high temperature heat treatment Thus, an ultra-thin metal silicon melt is interposed between the single-crystal silicon carbide substrate and the polycrystalline silicon carbide substrate during the heat treatment, and the single-crystal silicon carbide is placed on the single-crystal silicon carbide substrate. Is characterized by liquid phase epitaxial growth.

Then, you Keru heat treatment method in the liquid phase Epitakisharu growth method of a single crystal carbide Kei element of the present invention, the closed container, preliminarily pressure of about 10- ⁵ P a following approximately 800 ° in a high vacuum preheating chamber with heating above and C, the sealed vessel was evacuated to below a pressure of about 10- ⁵ P a, in advance about 1400 ° C or higher 2300 ° C temperature range below a pressure of about 10_ heated to a predetermined temperature within ² P a vacuum below, preferably about 10- ⁵ Pa or less of vacuum, or pre after reaching a pressure of about 10- ⁵ P a high vacuum below the heating chamber under slight lean gas atmosphere with an inert gas is introduced By moving and installing, the single crystal silicon carbide substrate and the polycrystalline silicon carbide substrate are heated to a predetermined temperature within a temperature range of about 1400 ° C or more and 2300 ° C or less in a short time, and the microcrystalline silicon carbide substrate is heated. absence of grain boundaries, microphone port pipe defect density on the surface is about 1 / cm ² or less single crystal carbide Kei And JP ί Christian to produce.

As described above, since it is possible to heat to a predetermined temperature within a temperature range of about 1400 ° C. or more and 2300 ° C. or less in a short time, single crystal Si C can be efficiently formed. Further, there is no fine grain boundaries ingrowth crystal, the density of the microphone port pipe surface defects can be about 1 / cm ² or less of the single crystal S i C, it is possible to apply a variety of semiconductor devices . Here, a micropipe defect is also called a pinhole, and is a tubular void having a diameter of several μηι or less that exists along the crystal growth direction. The single-crystal SiC substrate serving as a seed crystal to be used can be formed on all crystal planes of 4H-SiC and 6H-SiC, but preferably uses a (0001) Si plane. . The polycrystalline SiC substrate has an average particle size of about 5 _μm or more and 10 zm It is preferable that the particles have the following particle diameters and the particle diameters are substantially uniform. Therefore, polycrystalline

The crystal structure of S i C is not particularly limited, and any of 3 C—S i C, 4 H—S i C, and 6 H—S i C can be used, but preferably 3 C—S i C.

Further, according to the present invention, during heat treatment, Si penetrates into the corners of the interface between the single-crystal SiC substrate and the polycrystalline SiC substrate due to the capillary action, so that ultrathin metal Si melt is obtained. Form a layer. The C atoms flowing out of the polycrystalline SiC substrate are supplied to the monocrystalline SiC substrate through the Si melt layer, and are grown on the monocrystalline SiC substrate as liquid crystalline epitaxy as monocrystalline SiC. I do. Therefore, induction of defects can be suppressed from the beginning to the end of growth. Further, unlike the conventional case, it is not necessary to immerse in the molten Si for the treatment, so that after the heat treatment, the Si that is deposited on the single-crystal SiC substrate and the polycrystalline SiC substrate serving as seed crystals is removed. The amount is extremely small. In addition, since the ultra-thin metal Si melt is interposed between the single-crystal SiC substrate and the polycrystalline SiC substrate during the heat treatment, the metal Si necessary for the epitaxial growth of the single-crystal SiC is Only one can be used for liquid phase epitaxial growth of single crystal sic. For this reason, the contact area with the outside is minimized in the thin Si layer during the heat treatment, so that the probability of entry of impurities is reduced, and a high-purity single crystal SiC can be formed.

Heat treatment apparatus of the present invention, the object to be processed with less pressure of about 1 CT ² P a, preferably preferably to less than about 1 0 _ ⁵ P a vacuum below, or pre-pressure of about 1 0- ² P a of about 1 0 - within a short time of about 1 2 0 0 ° C over 2 3 0 0 ° C following temperature range in the ⁵ P a following under lean gas atmosphere with an inert gas is introduced after reaching the vacuum to a predetermined temperature A heating chamber to be heated, a front chamber connected to the heating chamber, and a moving unit for moving the processing object to the heating chamber, and a heating chamber connected to the front chamber; 1 0- ² P a less preferably about 1 0 ⁵ P a preliminary heating to advance about 8 0 0 ° C or higher in the following vacuum And a heating chamber.

Further, in the heat treatment apparatus of the present invention, the inside of the vacuum high-temperature furnace is composed of two or more separate tanks, and the inside of the plurality of tanks is composed of a main heating tank and a preheating tank. It is heated from room temperature to about 800 ° C to degas mainly the gas adsorbed on the sample and the gas contained in the sample.After the degassing is completed, the sample is evacuated by heating beforehand and kept at a clean high temperature. The main heating tank is quickly moved to the main heating tank, and the main heating tank always reaches a pressure of about 10 -3 Pa or less, or once reaches a pressure of about 10 -3 Pa or less. Introduce a small amount of inert gas and set it within the range of about 800 ° C or more and 260 ° C or less under a rare gas atmosphere of any pressure from atmospheric pressure to about 10-3 Pa. The preheating tank is always heated to a high temperature, and the preheating tank moves the sample from the main heating tank to the atmospheric pressure for loading and unloading the sample. Has the function of evacuating to the same pressure as that of the main heating tank, and preliminarily heating the sample from room temperature to a temperature of about 800 ° C, and then moving to the main heating tank quickly. Therefore, it has a high-temperature heating furnace that quickly achieves a high-temperature, high-purity atmosphere at a predetermined temperature within a temperature range of about 800 ° C or more and 260 ° C or less. I do.

Furthermore, in the heat treatment apparatus of the present invention, the vacuum high-temperature furnace is divided into a main heating tank and a preheating tank in order to rapidly heat the sample, and each chamber is maintained in a high-purity atmosphere. Each independent vacuum pumping system, or each independent gas introduction system, and can be maintained at atmospheric pressure, and the main heating tank and the preheating tank power can be opened and closed by shutting off each other to integrate and separate. In a heat treatment apparatus having a high-speed high-temperature heating furnace maintained at a pressure of about 10-3 Pa or less, or once at a pressure of about 10-3 Pa or less during normal use of the main heating tank After that, a small amount of inert gas is introduced, and about 80 to about 10-3 Pa in a rare gas atmosphere at an arbitrary pressure from about 10 to 3 Pa. The temperature is maintained at a predetermined high temperature within a temperature range of 0 ° C or more and 2600 ° C or less, and the preheating tank is maintained at a predetermined temperature within a temperature range of about room temperature or more and 1000 ° C or less. In the state, it has a built-in cold trap to adsorb the built-in gas generated from the sample etc., and has a built-in high temperature heating furnace with a built-in quenching gas circulation device to quickly cool from high temperature after heating to room temperature. It is characterized by the following. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic cross-sectional view of an embodiment of a heat treatment apparatus used for a liquid phase epitaxial growth method of single crystal SiC according to an embodiment of the present invention. FIG. 2 is a schematic view showing an example of the closed container used in one embodiment of the present invention.

FIG. 3 is a diagram showing the inside of the closed container in one embodiment of the present invention. FIG. 4 is a diagram showing a state where a substrate is placed in a lower container according to an embodiment of the present invention.

FIGS. 5A and 5B are schematic diagrams showing an example of a reflecting mirror used in an embodiment of the present invention.

FIGS. 6 (a) and 6 (b) are diagrams showing microscopic photographs of the surface of a single crystal SiC growth layer obtained by the heat treatment method and the heat treatment apparatus according to one embodiment of the present invention. FIG. 6 (a) is a diagram showing a surface morphology, and FIG. 6 (b) is a diagram showing a micrograph showing a cross section thereof.

FIGS. 7 (a) and 7 (b) are views showing AFM images of the surface of the single crystal SiC shown in FIGS. 6 (a) and 6 (b), and FIG. Surface morphology Fig. 7 (b) is an AFM image showing the cross section.

FIGS. 8 (a), 8 (b) and 8 (c) show the growth process of single crystal SiC obtained by the heat treatment method and the heat treatment apparatus according to one embodiment of the present invention. FIG. 4 is a view for explaining a step punching mechanism in the step.

9 (a) and 9 (b) are cross-sectional views of main parts of a heat treatment apparatus according to another embodiment of the present invention.

FIG. 10 is a diagram showing the relationship between the spectral emissivity and the reflectance at a high temperature of W. .

FIG. 11 is a diagram showing the wavelength energy of W in the range from 180 ° C. to 260 ° C. '

FIG. 12 is a diagram showing the spectral reflection characteristics of Au covering the surface of the metal reflector 5.

FIG. 13 is a cross-sectional view of a main part of a heat treatment apparatus according to still another embodiment of the present invention.

FIG. 14 is a diagram showing an example of a heating temperature characteristic according to the embodiment shown in FIG.

FIG. 15 is a cross-sectional view of a main part of a heat treatment apparatus according to still another embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an example of a heat treatment apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of a heat treatment apparatus according to the present invention. In FIG. 1, the heat treatment apparatus 1 includes a heating chamber 2, a pre-heating chamber 3, and a pre-chamber 4 continuing from the pre-heating chamber 3 to the heating chamber 2. The workpiece 5 is sequentially moved from the pre-heating chamber 3 to the pre-chamber 4 and the heating chamber 2 to grow single crystal SiC.

As shown in FIG. 1, in the heat treatment apparatus 1, a heating chamber 2, a preheating chamber 3, and a front chamber 4 communicate with each other. For this reason, it is necessary to control each chamber to a predetermined pressure in advance. Becomes possible. Further, by providing a gate valve 7 or the like for each chamber, it is also possible to adjust the pressure for each chamber. Thus, even when the object 5 is moved, the inside of the furnace under a predetermined pressure can be moved by a moving means (not shown) without touching the outside air, so that contamination of impurities can be suppressed. .

The preheating chamber 3 is provided with a heating means 6 such as a lamp such as a halogen lamp or a calorie heating means 6 such as a rod heater, and capable of rapidly heating to about 800 ° C or more and about 100 ° C or less. Has become. As the heating means, a lamp-type heating means such as a halogen lamp is preferred! Further, a gate valve 7 is provided at a connection portion between the preheating chamber 3 and the front chamber 4 to facilitate the pressure control of the preheating chamber 3 and the front chamber 4.

The object 5 is in a state of being placed on the table 8 of the preheating chamber 3, from about 1 0 ^"2 P a less is the pressure of Jo Tokoro, preferably under a vacuum of less than about 1 0- ⁵ Pa After being preheated to 800 ° C or more in the preheating chamber 3 and the front chamber 4, as soon as the pressure has been adjusted, the preheating chamber 3 is moved to be installed on the elevating susceptor 9 provided in the front chamber 4. Let me do.

The workpiece 5 moved to the front chamber 4 is moved from the front chamber 4 to the heating chamber 2 by the vertically moving means 10 shown in part. At this time, the heating chamber 2 is shown Shinare, about 1 0 one ¹ P a less in advance predetermined pressure in the vacuum ordinary man, less preferably about 1 0- ² P a, more preferably from about 1 0 one ⁵ Pa or less vacuum, or pre-pressure of about 1 0 ² P a or less, preferably, to introduce some inert gas after reaching the high vacuum of below about 1 0 ⁵ P a, about 1 0 or less, preferably about 1 0 _ ² P a following and under a lean atmosphere, about 8 0 0 ° C or higher by the heating heater motor 1 1 2 6 0 0 ° C or less, preferably in the range of from about 1 2 0 0 It is preferable that the temperature is set to not less than ° C and not more than 230 ° C.

The condition in the heating chamber 2 is set in this way, and the workpiece 5 is By moving the object 5 into the heating chamber 2, the object 5 is heated to a temperature of about 800 ° C. or more and 260 ° C. or less, preferably, about 1200 ° C. or more and 230 ° C. It can be rapidly heated to a predetermined temperature within the following range.

In the heating chamber 2, a reflecting mirror 12 is disposed around the heater 11, and reflects the heat of the heater 11 so as to reflect the heat of the heater 5, which is located inside the heater 11. I try to focus on it.

The reflecting mirror 12 may be a case-shaped reflecting mirror 12 as shown in FIG. 1, for example, a dome-shaped reflecting mirror 12 as shown in FIGS. 5 (a) and 5 (b). You can also. By making the reflecting mirror 12 dome-shaped, it is possible to use a flat heater for the heater 11, and even if the flat heater 11 is used, the heating can be performed. The heat from the heater 11 can be efficiently concentrated on the workpiece 5.

The fitting part 25 between the moving means 10 and the heating chamber 2 includes a convex stepped part 21 provided in the moving means 10 and a concave stepped part 2 formed in the heating chamber 2. It consists of two. The heating chamber 2 is sealed by a sealing member such as an O-ring (not shown) provided at each step of the stepped portion 21 of the moving means 10.

A contaminant removal mechanism 20 is provided inside the heater 11 in the heating chamber 2 for removing contaminants leaking from the workpiece 5 so as not to contact the heater 11. ing. This can suppress the heater 11 from reacting with contaminants and deteriorating. The contaminants include, for example, Si vapor in the case of heat treatment in the liquid phase epitaxial growth method of single crystal SiC.

As described above, since the contaminant removing mechanism for removing contaminants such as silicon vapor leaking from the closed container is provided in the heating chamber, the silicon vapor or the like of the heating means such as the heater provided in the heating chamber is provided. Deterioration due to contaminants Can be prevented. Here, as the contaminant removing mechanism, a vacuum pump and other general exhaust means can be used.

The contaminant removing mechanism 20 is not particularly limited as long as it removes contaminants leaking from the inside of the processing object 5.

The heating heater 11 is a resistance heating heater made of a metal such as graphite or tantalum, and has a cylindrical shape with a side heater and a base heater 11 a installed on the susceptor 9. It consists of an upper heater lib. As described above, since the heater 11 is disposed so as to cover the object 5, the object 5 can be heated evenly. '

The heating method of the heating chamber 2 is not limited to the resistance heater shown in the present embodiment, but may be, for example, a high-frequency induction heating method. For example, in the case of a heat treatment in the liquid-phase epitaxial growth method of single-crystal SiC, a closed container 5 composed of an upper container 5a and a lower container 5b as shown in FIG. Is preferred. As described later, a single-crystal SiC substrate 16 and a polycrystalline SiC substrate are stacked and stored in the closed container 5 and heat-treated (see FIG. 3).

As shown in FIG. 2, the closed container 5 is composed of an upper container 5a and a lower container 5b, and each is formed of either tantalum or tantalum carbide.

. Sealed container is formed of a tantalum or tantalum carbide because, while suppressing the S i C of the sealed container, the heating chamber to ensure that the pressure of about 1 0 - can be less than or equal to ² P a.

It is preferable that the play of the fitting portion when fitting the upper container 5a and the lower container 5b is about 2 mm or less. As a result, it is possible to suppress the entry of impurities into the closed container 5. Also, by setting the play to about 2 mm or less, the partial pressure of Si in the closed vessel 5 does not become 10 Pa or less. Can also be controlled. Therefore, the partial pressure of SiC and the partial pressure of Si in the sealed container 5 are increased, and the monocrystalline SiC substrate 16 and the polycrystalline SiC substrates 14, 15 and ultrathin metal Si The liquid 17 contributes to the prevention of sublimation. If the play of the fitting portion at the time of fitting the upper container 5a and the lower container 5b is larger than about 2 mm, the partial pressure of Si in the closed container 5 is controlled to a predetermined pressure. Not only is difficult, but also impurities may enter the sealed container 5 via the fitting portion, which is not preferable. As shown in FIG. 2, the shape of the closed container 5 is not limited to a square, but may be a circular one. As described above, the closed container is formed by the upper container and the lower container, and the pressure in the closed container is increased to such an extent that the silicon vapor leaks from the fitting portion between the upper container and the lower container. It is characterized by controlling the pressure to be higher than the pressure and suppressing the contamination of the closed container with impurities.

With such a structure of the closed container, entry of impurities into the closed container can be suppressed. As a result, the purity of the bag ground is about 5 × 10 ¹⁵ / cm ³ or less.

Further, the lower container 5b is provided with three support portions 13 as shown in FIGS. The supporting portion 13 supports a polycrystalline SiC substrate 14 serving as a seed crystal described later. Note that the support portion 13 need not be a pin-shaped member as shown in the present embodiment, but may be a ring-shaped member made of, for example, SiC.

Figure 3 shows a 6 H-type single crystal SiC substrate 16 serving as a seed crystal installed in a closed container 5 in which the upper container 5a and the lower container 5b are fitted together, and the single crystal S This figure shows the state of a polycrystalline SiC substrate 15 sandwiching the iC substrate 16 and an ultra-thin metal Si melt 17 formed between them. The ultra-thin metal Si melt 17 is formed during heat treatment, and the Si source of the ultra-thin metal Si melt 17 is a single crystal SiC substrate serving as a seed crystal. 1 6 surface The method is not particularly limited, such as forming a film of metal Si in advance so as to have a thickness of about 10 μπη to 50 μιη by CVD or placing Si powder in advance. As shown in FIG. 3, the single crystal SiC substrate 16, the polycrystalline SiC substrates 14, 15 and the ultra-thin metal Si melt 17 are provided in a lower container 5b constituting a closed container 5. And is housed in a closed container 5. Here, the single-crystal SiC substrate 16 was cut into a desired size (10 X 1 Omm or more and 20 X 2 Omm or less) from a single crystal 6H—SiC substrate manufactured by the sublimation method. It is. In addition, the polycrystalline SiC substrates 14 and 15 can be cut out to a desired size from SiC used as a dummy wafer in a Si semiconductor manufacturing process manufactured by a CVD method. . The surfaces of these substrates 16, 14, and 15 are mirror-polished, and oils, oxide films, metals, and the like adhering to the surfaces are removed by washing or the like. Here, the polycrystalline SiC substrate 14 located on the lower side is for preventing erosion of the monocrystalline SiC substrate 16 from the closed vessel 5 and is formed by liquid phase epitaxial growth on the monocrystalline SiC substrate 16. This contributes to the improvement of the quality of single crystal SiC.

Further, in this closed container 5, it is possible to install together with Si pieces for controlling sublimation of SiC and evaporation of Si during the heat treatment. By simultaneously installing the Si pieces, they are sublimated during the heat treatment to increase the SiC partial pressure and Si partial pressure in the closed vessel 5, and the single crystal SiC substrate 16 and the polycrystalline SiC substrate 14, 15. It contributes to the prevention of sublimation of ultra-thin metal Si melt 17. In addition, the pressure in the closed vessel 5 can be adjusted to be higher than the pressure in the heating chamber 2, whereby the Si vapor is always discharged from the fitting portion between the upper vessel 5a and the lower vessel 5b. Can be released and impurities can be prevented from entering the closed container 5. Closed container 5 thus configured as described above, after being installed in the preheating chamber 3, below about 10- ² P a, preferably, is set equal to or less than about 10- ⁵ P a, preliminary Caro It is heated to about 800 ° C. or more, preferably about 1000 ° C. or more, by a heating means 6 such as a lamp and / or a mouth heater provided in the heat chamber 3. In this case, as well inside the heating chamber 2, about 10- ² P a or less, preferably, after being set to less than about 10 one ⁵ P a, about 800 ° C or higher 2600 ° C or less in the range, good rare Preferably, it is preferably heated to a predetermined temperature in the range of about 1200 ° C to 2300 ° C.

The closed vessel 5 preheated in the preheating chamber 3 opens the gate valve 7 and moves to the susceptor 9 in the front chamber 4, and is moved by the elevating means 10 in a range of about 800 ° C to 2600 ° C, Preferably, it is moved into the heating chamber 2 which is heated to a predetermined temperature in the range of about 1200 ° C or more and 2300 ° C or less. As a result, the temperature of the sealed container 5 is rapidly increased within a short time within about 30 minutes within a range from about 800 to 2600 ° C, preferably from about 1200 to 2300 ° C. Heated. The heat treatment temperature in the heating chamber 2 may be a temperature at which the metal Si pieces simultaneously installed in the closed vessel 5 are melted, but in the present embodiment, it is in a range of about 1200 ° C or more and 2300 ° C or less. At a predetermined temperature. As the processing temperature is increased, the wettability between the molten Si and SiC increases, and the molten Si becomes a single-crystal SiC substrate 16 and a polycrystalline SiC substrate 14, 1έ due to a capillary phenomenon. It is easy to penetrate between. As a result, an ultrathin metal Si melt 17 having a thickness of about 50 μιη or less can be interposed between the single-crystal SiC substrate 16 and the polycrystalline SiC substrates 14 and 15.

According to the heat treatment apparatus according to the present embodiment, it is possible to set the predetermined temperature within a range of about 800 ° C. to 260 ° C. in a short time, preferably within a range of about 1200 ° C. to 2300 ° C. Therefore, crystal growth can be completed in a short time, and the efficiency of crystal growth can be improved.

Also, the heat treatment time is such that the generated single crystal S i C has a desired thickness. It can be appropriately selected as described above. Here, as the amount of the metal Si as the Si source increases, the amount melted during the heat treatment increases, and when the ultra-thin metal Si melt has a thickness of about 50 μm or more, the metal Si melt is melted. The liquid becomes unstable and the transport of C is hindered, and Si not suitable for growing single crystal SiC and not necessary for forming single crystal SiC melts and accumulates at the bottom of the closed vessel 5. However, it is necessary to remove the metal Si solidified again after the formation of the single crystal SiC. For this reason, the size and thickness of the metal Si are appropriately selected according to the size of the single crystal SiC to be formed.

By the way, the growth mechanism of single-crystal SiC will be briefly described. Melt Si penetrates between the single-crystal SiC substrate 16 and the upper polycrystalline SiC substrate 15 due to the heat treatment. Then, a metal Si melt layer 17 having a thickness of about 30 μηι or more and 50 μm or less is formed at the interface between the substrates 16 and 15. The metal Si melt layer 17 becomes thinner as the heat treatment temperature increases,

It is about 0 μηι. Then, the C atoms flowing out of the polycrystalline SiC substrate 2 are supplied to the monocrystalline SiC substrate 16 through the Si melt layer, and the monocrystalline SiC

Liquid phase epitaxial growth (hereinafter referred to as LPE) as a 6H—SiC single crystal on 1C substrate 1. As described above, since the distance between the single-crystal SiC substrate 16 serving as a seed crystal and the polycrystalline SiC substrate 14 is small, no thermal convection is generated during the heat treatment. Therefore, the interface between the formed single crystal SiC and the single crystal SiC substrate 16 serving as a seed crystal becomes extremely smooth, and no distortion or the like is formed at this interface. Therefore, a very smooth single crystal SiC is formed. In addition, since the nucleation of SiC is suppressed during the heat treatment, the generation of the fine crystal grain boundaries of the formed single crystal SiC can be suppressed. In the method for growing single-crystal SiC according to the present embodiment, the force of molten Si penetrating only between single-crystal SiC substrate 16 and polycrystalline SiC substrate 15 is considered. However, since other impurities do not penetrate into the growing single crystal SiC, Bagdara It is possible to produce a single crystal SiC having a high purity of about 5 × 10 ¹⁵ cm ³ or less.

Above such a heat treatment apparatus according to the present embodiment, the object to be treated to a pressure of about 1 0 one ² P a or less, preferably about 1 0- ⁵ P a vacuum below, or pre-pressure of about 1 0 ^"2 P a below preferably about 1 0- ⁵ P a following in lean gas atmosphere was introduced inert gas after reaching the vacuum briefly at about 8 0 0 ° C over 2 6 0 0 ° C or less range, Preferably, a heating chamber for heating to a temperature range of about 1200 ° C. or more and 230 ° C. or less, and a moving means connected to the heating chamber and for moving an object to be processed to the heating chamber are provided. a front chamber provided, 'coupled to said front chamber, the object to be treated for about 1 0- ² P a less preferably about 1 0- ⁵ P a previously about 8 0 0 ° C or more in the following vacuum There is a pre-heating chamber for heating the room 7.

Then, according to the heat treatment apparatus of the present embodiment, a pressure of about 1 0 ² P a following lower and preferably about 1 0 - ⁵ P a vacuum below, or previously pressure of about 1 0 ² P a less preferably about 1 ^0-5 introduce some inert gas after reaching the P a high vacuum below about 1 0 - ¹ P a or less, preferably about 1 0 - in ² P a under less lean gas atmosphere, a short time Heating to a predetermined temperature in the range of about 800 ° C or more and 260 ° C or less, preferably in the range of about 1200 ° C or more and 230 ° C or less. Therefore, when single crystal SiC is formed as an object to be processed, a surface of about 10 μm or more can be formed on the surface, which has been difficult by the conventional liquid crystal growth method of single crystal SiC (LPE method). It becomes possible to form a single crystal SiC having a terrace of this type.

The heat treatment method according to an embodiment of the present invention, the preferably pre-pressure of about 1 0- ² P a following processing object about 1 0- ⁵ P a following approximately 8 0 in the preliminary heating chamber of the vacuum 0 After heating to at least ° C, a predetermined temperature within the range of approximately 800 ° C or more and 260 ° C or less, preferably within the range of approximately 1200 ° C or more and 230 ° C or less. A vacuum heated to a temperature of about 10 to ² Pa or less, preferably about 10 to ⁵ Pa or less, or a pressure of about 0.1 to ² Pa or less, preferably about 10 to ⁵ Pa or less By moving to a heating chamber under a rare gas atmosphere into which an inert gas has been introduced after the vacuum has been reached, the object to be treated can be quickly cooled to a temperature within a range of about 800 ° C to 260 ° C. Preferably, it is a heat treatment method of heating to a predetermined temperature within a range of about 1200 ° C. or more and 230 ° C. or less.

Further, in the heat treatment method in the liquid phase epitaxial growth method of single crystal silicon carbide according to the embodiment of the present invention, the single crystal silicon carbide substrate serving as a seed crystal and the polycrystalline silicon carbide substrate are overlapped with each other in an airtight container. And performing a high-temperature heat treatment so that an ultra-thin metal silicon melt is interposed between the single-crystal silicon carbide substrate and the polycrystalline silicon carbide substrate during the heat treatment. This is a heat treatment method for liquid phase epitaxial growth of single-crystal silicon carbide on a silicon substrate.

Then, vacuum the sealed container, with heating to about 8 0 0 ° C or higher in advance a pressure of about 1 0- ² P a less preheating chamber, the closed container below the pressure of about 1 0- ⁵ P a A pressure of about 140 to ² Pa or less, preferably about 10 to ⁵ Pa or less, or a vacuum preheated to a predetermined temperature within a range of about 140 to 230 ° C. by installing moved to the heating chamber under the lean gas atmosphere with an inert gas is introduced after reaching below a pressure of about 1 0- ⁵ P a, the single crystal carbide Kei arsenide substrate and the polycrystalline carbide Kei arsenide substrate Is heated to a predetermined temperature within a temperature range of about 140 ° C. or more and 230 ° C. or less in a short time so that there is no fine crystal grain boundary. A single crystal silicon carbide having a size of not more than cm ² is produced.

In addition, when the closed container is moved to the heating chamber, a temperature gradient is not provided in an axial direction of the closed container, a temperature gradient is provided in an in-plane direction of the closed container, and the temperature gradient is arbitrary. Control of fine grain boundaries Control. The axial direction of the closed container means a direction in which the single-crystal silicon carbide substrate and the polycrystalline silicon carbide substrate are stacked in the closed container, and the in-plane direction of the closed container is The direction perpendicular to the lamination direction, that is, the plane direction of the crystal surface.

Since there is no temperature difference in the axial direction of the closed vessel, no temperature difference is formed between the single crystal SiC substrate and the polycrystalline SiC substrate, so that heat treatment can be performed in a thermal equilibrium state. Also, since the metal Si melt is thin, thermal convection is suppressed. Therefore, induction of defects can be suppressed from the beginning to the end of growth. Furthermore, since nucleation is suppressed during the heat treatment, the formation of fine crystal grain boundaries of the formed single crystal S i C can be suppressed. In addition, a simple heat treatment apparatus can be used, and strict temperature control during heating is not required, so that manufacturing costs can be significantly reduced. In addition, by providing a temperature gradient in the in-plane direction of the closed vessel, the temperature gradient can be arbitrarily controlled, so that during the growth of single crystal SiC, the fine crystal grain boundaries are shifted from the high temperature side to the low temperature side of the temperature gradient. Thus, single crystal SiC can be grown so as to move to a single crystal, and as a result, single crystal SiC having a microphone opening pipe defect density of about 1 / cm ² or less can be formed.

The ultra-thin metal Si melt has a thickness of about 50 μm or less.

Since the ultrathin metal Si melt interposed between the single crystal SiC substrate and the polycrystalline SiC substrate during the heat treatment is about 50 μm or less, preferably about 30 m or less, C dissolved from the polycrystalline SiC substrate is transported by diffusion to the surface of the monocrystalline SiC substrate, and the growth of the monocrystalline SiC is promoted. When the thickness of the ultra-thin metal silicon melt is about 50 μm or more, the metal silicon melt becomes unstable, and the transport of C is hindered, which is not suitable for growing single crystal SiC. According to the present invention, local liquid phase epitaxial growth can be performed at a high temperature in the same environment as a conventional high-temperature heat treatment environment such as a sublimation method. Therefore, micropipe defects can be closed without inheriting the micropipe defects contained in the seed crystal. In addition, since the growth surface is always in contact with the Si melt, an Si excess state is formed, and the generation of defects due to the shortage of Si is suppressed, and the growth of the Si melt in use is prevented. Since the contact area is small, impurities can be suppressed from entering the growth surface, and high-quality and high-performance single-crystal SiC with high purity and excellent crystallinity can be grown. However, compared to the conventional LPE method, this growth method can be performed at a very high temperature and can be performed in a short time, so that the growth rate can be remarkably increased as compared with the conventional LPE method. The growth efficiency of high-quality single crystal SiC can be extremely increased. Furthermore, there is no need to strictly control the temperature gradient during single crystal growth, and a simple apparatus can be used. Based on these facts, compared to existing semiconductor materials such as SiGaAs, single crystal S, which is expected to be a power device and semiconductor material for high-frequency devices, is superior in high temperature, high frequency, withstand voltage and environmental resistance. The practical application of i C can be promoted.

FIGS. 6A and 6B are micrographs showing the surface state of the single crystal SiC grown by the method described above. Fig. 6 (a) shows the surface morphology, and Fig. 6 (b) shows its cross section. As shown in Figs. 6 (a) and 6 (b), very flat terraces and step structures can be observed on the crystal growth surface by the LPE method.

FIGS. 7 (a) and 7 (b) show the results of observing the surface with an atomic force microscope (hereinafter, referred to as AFM). As can be seen from FIGS. 7 (a) and 7 (b), the step heights are about 4.0 nm and about 8.4 nm, respectively. This is an integer multiple height based on three molecular layers of SiC molecules (SiC monolayer is 0.25 ηπι). Thus, it can be seen that the surface is very flat. Thus, the surface of the single crystal S i C has a trilayer as a minimum unit. It has an atomic order step and a wide terrace, wherein the width of the terrace is about

10 m or more.

Since the terrace width is about 1 μμπι or more, the growth surface does not need to be subjected to surface treatment such as machining after the formation of single crystal SiC. For this reason, it is possible to produce a product without going through a processing step.

In addition, no micropipe defects are observed on the surface, as can be seen from the microscope images of the surface morphology in FIGS. 6 (a) and 6 (b). These things do et al, single crystal S i C obtained by the heat treatment apparatus according to the present invention, the density of micropipe defects formed on the surface of about 1 / c ² or less and very small no longer formed on the surface The terrace width is as wide as about 1 O ^ m or more, indicating that it is flat and has few defects.

In general, epitaxial growth of crystals is performed for each molecular layer. However, the single crystal SiC according to the present embodiment has a surface with a wide terrace of about 1 μm or more and a step having a height of a minimum of three molecular layers. This suggests that step bunching occurred during the crystal growth process. This step bunching mechanism can be explained by the effect of surface free energy during crystal growth. In the single crystal 6Η—SiC according to the present embodiment, there are two kinds of stacking cycle directions, ABC and ACB, in the unit stacking cycle. Therefore, by assigning numbers 1, 2, and 3 from the layers that are bent in the stacking direction, three types of surfaces can be defined as shown in FIGS. 8), 8 (b) and 8 (c). The energy of each surface is determined as follows (T. Kimoto, et al., J. Appl. Phys. 81 (1997) 3494-3500).

6 H 1 = 1.3 3 m e V

6H2 = 6.56 m e V

6H3 = 2.34me V Since the energy differs depending on the surface, the spread speed of the terrace differs. In other words, the higher the surface free energy of each surface, the higher the growth rate of the terrace ', and as shown in Figs. 8 (a), 8 (b) and 8 (c), the step hunting occurs every three periods. Happens. Further, in the present embodiment, the number of unbonded hands coming out of the step surface differs every other stage due to the difference in the lamination period (ABC or ACB). Due to the difference, it is thought that further step punching occurs in units of three molecules. The forward speed of one step is considered to be slow where one unjoined hand exiting the step is fast and two where it is fast. In this way, in 6H-S i C, step bunching proceeds in units of half integral multiples of the lattice constant, and after growth, the surface of the single crystal S i C has a minimum height of three molecular layers. Steps and a flat terrace.

As described above, the terrace of the single crystal SiC according to the present invention is formed by step bunching. Therefore, the steps are formed intensively near the end of the single crystal SiC. Figures 6 (a), 6 (b), 7 (a), and 7 (b) described above show the end portions of the single crystal SiC in order to observe the step portion. .

Further, the single crystal S i C obtained by the heat treatment apparatus in the present embodiment has a growth temperature in the range of about 1400 ° C. or more and 2300 ° C. or less, which is lower than the liquid phase growth temperature of the conventional single crystal S i C. It is very high and can be heated to a temperature of about 1400 ° C or more and 2300 ° C or less in a short time. As the growth temperature increases, the dissolved concentration of C in the Si melt formed between the single-crystal SiC as a seed crystal and the polycrystalline SiC increases. It is also considered that the diffusion of C in the Si melt increases with increasing temperature. As described above, since the C source and the seed crystal are very close to each other, a high growth rate of about 500 Mm / hr can be achieved depending on conditions. Thus, the single crystal S i C according to the present embodiment, since the density of micro-pipes defects of the surface is at 1 / cm ² or less, about 1 0 / m or more wide terraces are formed, After the single crystal SiC formation, surface treatment such as machining is not required. Further, since there are few crystal defects, it can be used as a light emitting diode or various semiconductor diodes. In addition, since the growth of the crystal depends on the temperature (not dependent on the surface energy of the seed crystal and the crystal of the source of C), the need for strict temperature control in the processing furnace is eliminated. In addition, since the space between the single crystal SiC as the seed crystal and the polycrystalline SiC as the supply source of C is extremely small, the manufacturing cost can be significantly reduced. In addition, since a temperature difference is hardly formed between the single crystal S i C serving as a seed crystal and the polycrystal S i C serving as a supply source of C, the heat convection of the seed crystal can be suppressed. As described above, the single crystal SiC grows in the plane direction of the crystal surface, and therefore, by providing a temperature gradient in the plane direction of the closed vessel, the crystal is grown. The direction of growth can be directed from high temperature to low! / The temperature gradient can be exemplified by a method of providing a temperature difference between the side heaters 11b located on the side wall side of the closed vessel 5 of the heater 11 provided in the heating chamber 2. By controlling the magnitude of the temperature gradient, the crystal growth rate can be controlled, and the generation of fine grain boundaries on the crystal surface can be suppressed.

In the present embodiment, 6 H—S i C is used as the seed crystal, but 4 H—S i C may be used.

In the present embodiment, (001) Si was used as the seed crystal, but another crystal orientation such as (11-20) may be used. .

When the plane orientation of the surface is (0 0 0 1) Si plane, compared with other crystal planes, Low surface energy and therefore high nucleation energy during growth, making nucleation difficult. For the above reasons, single crystal S i C with a wide terrace width can be obtained after liquid phase growth. The plane orientation of the surface is not limited to the (0001) Si plane, and it is possible to use all crystal planes of 4H-SiC and 6H-SiC.

Further, the single crystal SiC according to the present invention is formed by appropriately selecting the size of the single crystal SiC serving as a seed crystal and the size of the polycrystalline SiC substrate serving as a supply source of C. The size of the crystal S i C can be controlled. Also, since no strain is formed between the formed single crystal S i C and the seed crystal, the single crystal S i C having a very smooth surface can be obtained, so that it is applied as a surface reforming film. It is also possible.

Furthermore, a single crystal SiC as a seed crystal and polycrystalline SiC, which is a source of C, are alternately stacked or arranged side by side and heat-treated by the above-described method, thereby simultaneously producing a large amount of the single crystal SiC. Can also be produced. In the method for producing a single crystal SiC according to the present invention, the polycrystalline SiC substrate and the metal Si may be preliminarily added with an impurity of a group III metal such as A1 or B, or Arbitrary control of the p-type and n-type conductivity of the grown crystal by sending a gas containing an element that controls the conductivity type of SiC, such as nitrogen, A1, or B, into the atmosphere during growth Is possible.

Next, an embodiment of another heat treatment apparatus suitable for carrying out the heat treatment method of the present invention will be described with reference to FIGS. 9 (a), 9 (b) to FIG. FIGS. 9A and 9B are cross-sectional views of main parts of another embodiment of a heat treatment apparatus suitable for performing the heat treatment method of the present invention.

As shown in FIGS. 9 (a) and 9 (b), the heat treatment apparatus according to the present embodiment has a high-temperature heating furnace 50. The high-temperature heating furnace 50 includes a main heating tank 51, a preheating tank 52, and a communication between the main heating tank 51 and the preheating tank 52. A vacuum valve 59 that enables separation and a jig that can move the sample 56 to be processed between the main heating tank 51 and the preliminary heating tank 52; The main part is configured. In the main heating tank 51 and the preliminary heating tank 52, a high-melting point metal main heater 53 and a preliminary heating heater 54 are provided, respectively.

Further, in the main heating tank 51, a high-melting-point metal reflection plate 55 that enables efficient heating by the high-melting-point metal main heater 53 is provided. Further, an adsorption trap 58 is provided in the preheating tank 52, so that the pressure in the preheating tank 52 can be maintained at a predetermined pressure.

The heating part of the main heating tank, that is, the heating heater 53 is composed of a cylindrical main heater (not shown) made of a high melting point metal and a planar auxiliary heater, and a heating control of these two heaters. By changing the sample position, it is possible to improve the temperature uniformity in the disc-shaped heating zone and to provide a temperature gradient in the in-plane direction in the disc-shaped heating zone.

For the heating source, that is, the heater in the main heating tank 51 and the preliminary heating tank 52, and the heat insulating material surrounding the heating source, avoid the use of graphite, which causes gas generation. Tungsten (W), a refractory metal with low gas adsorption, is mainly used as the reflector.

First, when the sample 56 is set in the preheating tank 52, the preheating tank 52 is evacuated from the atmospheric pressure to a vacuum by a vacuum pump (not shown). The pre-heater 54 heats the gas adsorbed on the sample and the gas contained in the sample 56 from room temperature to about 800 ° C from the room temperature. Exhausted by

As a heating source of the preheating tank, for rapid heating in a short time, An infrared heating lamp with a reflecting mirror for collecting near-infrared light on the sample and having an infrared-generating functional film added to the outer surface of the tare of the halogen or Xe lamp or lamp is used.

After the degassing of the sample 56 is completed, the sample 56 is preheated, evacuated, and moved within 1 minute to the main heating tank 51 maintained at a high temperature (see FIG. 9 (b)). The movement is performed by opening the vacuum valve 59 and raising the elevating table 57. The main heating tank 5 1 always high vacuum of about 1 0- ³ P a pressure below or, once, after reaching a high vacuum, to introduce some inert gas, to about 1 (T ² P a The temperature is constantly maintained at a predetermined high temperature within a range of about 800 ° C. or more, preferably about 180 ° C. or more and 260 ° C. or less under a set lean gas atmosphere.

Incidentally, the temperature range of the main heating tank is, for example, in the case of a heat treatment in a liquid phase epitaxial growth method of single crystal silicon carbide, in a range of about 120 ° C. or more and 230 ° C. or less. Preferably, the temperature is in the range of about 140 ° C. or more and 230 ° C. or less.

Then, after the transfer of the sample 56 to the main heating tank 51 is completed, the sample 56 has a predetermined high temperature within a range of about 1200 ° C. or more and 260 ° C. or less, that is, the sample 56 Achieve optimal processing temperature quickly. Since the main heating tank 51 is pre-heated, a uniform high temperature state can be maintained for a required processing time. Further, since the high melting point reflecting metal plate 55 is provided, the sample 56 can be efficiently heated by heat radiation.

The heating section of the main heating tank 51, that is, the heater, comprises a cylindrical main heater made of a high melting point metal and a planar auxiliary heater.

The wavelength energy emitted from the W heater is expressed by the following equation.

W wavelength energy = W spectral emissivity X Ideal black body wavelength energy The ideal black body wavelength energy can be easily calculated from the radiation law of P 1 ank. It is possible to

FIG. 10 is a diagram of the spectral emissivity and the reflectance of W. The spectral emissivity in the figure was calculated by the following equation described in the document 'The Science Of Incandescence' Dr. Milan R. Vukcevich. '

ε [, T] = a ίλ) -b [λ, T] {(Τ1 600) / 1 100 000} where ε: emissivity, λ: wavelength [μπι], Τ: temperature [ Κ]

The reflectance in FIG. 10 was calculated from Kirchhoff's law of the following equation.

'R = 1— ε

Here, R: reflectance, _ε : emissivity.

Fig. 11 shows the wavelength energy characteristics of the high-temperature region of W from 180 ° C to 260 ° C according to the 放射 1 ank radiation law.

From the results in Fig. 11, the wavelength energy in the high-temperature region of 180 ° C. or more and 260 ° C. or less has a peak between 1.0 ^ 111 and 1.5 μπι. It can be seen that most of the wavelength energy is in the wavelength range from .4 111 to 3.5 μΐη. In other words, at wavelengths of about 0.4 μm or more and 3.5 μππ or less, the reflective material having a reflective property enables highly efficient heating of the sample in the furnace.

Table 1 shows some examples of metals and compounds that can be used in this temperature range.

[table 1]

With reference to these, the processing temperature of the main heating tank is set to a predetermined temperature in the range of about 1200 ° C. or more and 260 ° C. or less. In a heating furnace, the heating part of the high-temperature furnace is made of a high melting point metal of W or Ta, and the material for the heat reflection and heat insulation area surrounding the high-temperature area is selected from W, Ta, and Mo It has a composite structure made of a high melting point metal material, and the wavelength that reflects the emission wavelength region of the heat generating part on the surface of the high melting point metal of the material in the heat insulation area is about 0.4 μm or more and about 3.5 μm. An infrared reflective film in an arbitrary wavelength range within the range of m or less is formed.

Specifically, W was used as a heater, and W and Ta were used as reflectors having wavelengths of about 0.5 to 3.5 μιτα mainly in the infrared region.

From Fig. 11, the peak wavelength energy of W radiation at 2200 ° C is about 1.1 μm, and the reflectance of W at this time is about 0.65. In the region where the wavelength energy is relatively high, about 1.1 μm or more and 3.0 μm or less, the reflectance increases as the wavelength becomes longer, and reaches 0.8 at 3.Ομηι. In other words, it can be said that the reflection characteristics of W are sufficient as a reflector of a W heater in a clean high-purity atmosphere.

Table 2 shows an example of the design of the metal reflector 55 surrounding the W heater and the sample, based on the relationship between the emissivity and the reflectivity at high temperatures of W in FIG. Each reflector 55 surrounds the heater 53 and the sample 56 in a sealed state, and the interval between the reflectors 55 is about 3 mm. Table 3 shows a configuration example of the high heat-resistant metal oxide formed on the high-melting point metal reflection plate 55 and the infrared reflection film.

2]

9-layer Ta / Ta / Ta / Ta / Mo / Mo / Mo / Mo / Mo

11-layer W / W / W / W / W / Mo / Mo / Mo / Mo / Mo / Mo

[Table 3] I ¾ temperature region w Metal reflector + WC Medium temperature region Mo metal reflector + Au Here, W, which is a high melting point metal, has a melting point of about 3400 ° C and Mo of about 2620 ° C. The WG given as an example in the present embodiment is about 2720 ° C, and Au is about 1060 ° C. Therefore, WC, which has a high melting point and is familiar with the substrate, was used on W, and Au, which had a relatively low melting point, was used on Mo. The reflectance of WC in the near-infrared region is relatively high in a smooth flat surface state depending on the film forming conditions. Au in the same region is a highly reflective material with a reflectivity of about 95% or more, but because of its low melting point, a film was formed on Mo in the latter half (outside) of the medium temperature region. FIG. 12 shows the spectral reflection characteristics of the eight-11 reflective layer in the wavelength range of 0.4 111 to 3.5 μΐΊ.

As described above, in the present embodiment, the heat retaining region composed of the high melting point metal plate surrounding the heater portion of the main heating tank has a composite structure including the heat retaining layer and the heat ray reflective layer, and each layer has a high temperature. It has the function of holding and reflecting heat rays, and the surface of the high melting point metal plate that constitutes the heat insulation area is made of a highly heat-resistant metal carbide such as WC, TaC, MoC, ZrC, HfC, BN, or By coating metal nitride alone or in combination, it has the function of preventing the deterioration and deformation of the high melting point metal, and the surface of the high melting point metal serving as the heat ray reflective layer reflects infrared rays such as Au. By being coated with a film, it has the function of reflecting efficiently an arbitrary emission wavelength range in the range of about 0.4 to 3.5 μm.

In the heat treatment apparatus according to the present embodiment, the inside of the vacuum high-temperature furnace is composed of two or more separate tanks as described above, and the insides of the plurality of tanks are configured with the main heating tank and the preliminary heating tank. The preheating tank is heated from room temperature to about 800 ° C to degas mainly the gas adsorbed on the sample and the gas contained in the sample. Said being held Is moved quickly to the main heating chamber and the main heating chamber is always about 1 0- ³ P a hereinafter pressure or, after reaching the time about 1 0- ³ P a pressure below, some of the inert introducing a gas from atmospheric pressure to about 1 0 - is always heated to a high temperature in any range of about 8 0 0 ° C over 2 6 0 0 ° C under a lean gas atmosphere at a pressure of up to ³ P a The preheating tank has a function capable of evacuating from the atmospheric pressure for loading and unloading the sample to a pressure equivalent to that of the main heating tank, which is necessary for moving the sample between the main heating tank and the main heating tank. After preheating the sample from room temperature to a temperature of about 800 ° C, the sample is moved to the main heating tank quickly, so that the optimum processing temperature of the sample is about 800 ° C or more, preferably 120 ° C or more. A high-temperature heating furnace that quickly achieves a high-temperature and high-purity atmosphere within a temperature range of 0 ° C or higher, more preferably 180 ° C or higher and 260 ° C or lower. It is characterized by having.

Incidentally, the temperature range of the main heating tank is, for example, in the case of a heat treatment in a liquid phase epitaxial growth method of single crystal silicon carbide, a range of about 1200 ° C. or more and 230 ° C. or less. Preferably, it is more preferably in the range of about 140 ° C. or more and 230 ° C. or less.

Further, in the heat treatment apparatus according to the present embodiment, in order to rapidly heat the sample, the vacuum high-temperature furnace is divided into two parts, a main heating tank and a preheating tank, and a high-purity atmosphere is maintained. The room can be maintained in an independent vacuum evacuation system or an independent gas introduction system and an atmospheric pressure atmosphere, and the main heating tank and preheating tank are integrated by opening and closing the shutoff valve. and the heat treatment apparatus having a high-speed high-temperature furnace which is maintained mutually separated, the main heating chamber is always about 1 0- ³ P a pressure below at regular or, less time about 1 0- ³ P a after reaching the pressure, some introducing an inert gas, about 8 0 0 ° C or more under a lean gas atmosphere any pressure from atmospheric pressure to about 1 0- ³ P a, preferably from about 1 2 0 0 ° C or more, more preferably about 180 ° C or more and 260 ° C or less It is held in a high temperature state in the inner, the preliminary When the heating tank is maintained at a temperature in the range of about room temperature to 100 ° C or less, a cold trap is built in to absorb the built-in gas generated from the sample, etc. It is characterized by having a high-temperature heating furnace with a built-in gas circulating device for rapid cooling to quickly cool to room temperature.

The temperature range of the main heating tank is, for example, in the case of a heat treatment in a liquid phase epitaxial growth method of single crystal silicon carbide, preferably in a range of about 120 ° C. or more and 230 ° C. or less. It is more preferably in the range of about 140 ° C. or more and 230 ° C. or less.

As described above, the heat treatment apparatus according to the present embodiment is divided into the main heating tank and the preliminary heating tank, and by clearly dividing the respective work assignments, it is possible to maintain the high-purity atmosphere in the main heating tank at the optimum processing temperature and to maintain the optimal processing temperature. To maintain the proper processing conditions. Here, the preliminary heating bath, by heating the sample in advance about 8 0 0 ° C or higher under 1 0 _ ³ P a pressure below, which performs temperature increase in the outgassing of removal and intermediate stage or is there. The main heating chamber is for heating sample 1 0- ³ P a following optimal treatment temperature in a short time under pressure, for example 1 8 0 0 ° or more C.

To move the sample between the main heating tank and the preheating tank, linear movement by air activation or high-speed movement within 1 minute by circular movement driven by a motor is possible. If a new gas is released in the main heating tank, a vacuum pump with sufficient exhaust capacity dedicated to the tank can be installed to quickly remove contaminated gas to the outside of the tank. It is. Furthermore, by providing an auxiliary physical adsorption removal mechanism such as a cold trap in the preheating tank, it is possible to more completely prevent the deterioration of the heaters and reflectors provided in the main heating tank.

In the case of the conventional heat treatment equipment, the sample soaking area is narrow and the soaking area Disadvantage that the temperature control in the region is difficult, heating atmosphere is a high vacuum (1 0 ³ under P a pressure below) or a slight case of rare gas atmosphere, disadvantage that it is difficult retaining contaminating not high temperature region of the impure gas was there. According to this embodiment, a large amount of the adsorption gas such as hydrogen and the built-in gas released from the sample in the initial stage of heating were sequentially heated (room temperature to 800 ° G) and exhausted in the preheating tank. After that, the sample is rapidly moved into the main heating tank in a high-purity processing atmosphere.In addition, when the optimal heating area of the sample is about 1200 ° C or more and 260 ° C or less, By preheating the main heating tank to about 800 ° C or more and 260 ° C or less, high-speed and uniform heating, which was not possible in the past, became possible. In addition, in the case of conventional heat treatment equipment, it took a long time to cool the sample to a working temperature close to room temperature after heat treatment, but this equipment has a built-in gas cooling device in the preheating tank. This enabled rapid cooling of the sample.

FIG. 13 shows still another embodiment of the heat treatment apparatus according to the present invention. In the present embodiment, the heat treatment apparatus has a high-temperature heating furnace 70. The preheating tank 52 in the present embodiment shown in FIG. 13 is provided with a halogen lamp or a mouth heater 54, and is quickly set within a range of about 800 ° C. or more and 180 ° C. or less. It is equipped with a lamp or open heater type heating furnace that can heat up to the temperature of '

In addition, cassettes 60 capable of loading a plurality of samples are arranged on both sides of the preheating chamber 52, and one of them is a pre-processed sample and the other is a processed sample in the other. The preheating chamber 52 a is partitioned by a vacuum valve 59. The main heating tank 51 includes a heater 53 made of a high melting point metal, for example, a W-shaped mesh heater and a metal reflecting plate 55 made of a high melting point metal.

In a high-temperature heating furnace 70, a sample 56 is placed on a jig and a lifting table 57 from a cassette 60 in which a plurality of unprocessed samples are loaded, and preheated. In tank 52, it is preheated to about 800 ° C. or higher. On the other hand, the main heating tank is previously heated to a predetermined temperature within a range of about 800 ° C or more and 260.0 ° C or less. The preheated sample 56 opens the vacuum valve 59 between the preheating tank 52 and the main heating tank 51 as soon as the pressure between the preheating chamber 52 and the main heating tank 51 is adjusted. Then, the sample 56, the jig and the elevating table 57 move, and are processed in the main heating tank 51 at a predetermined temperature within a range of about 800 ° C. or more and 260 ° C. or less. In this embodiment, the processing is performed at about 2000 ° C.

When the processing is completed in the main heating tank 51, the jig and the elevating table 57 descend, and the vacuum valve 59 between the preheating tank 52 and the main heating tank 1 is closed. Then, the sample is transported to a cassette 60 for receiving the heat-treated sample. By repeating this process, it can be seen that the batch-type processing furnace is remarkably improved in a short time and in mass productivity.

FIG. 14 shows an example of the heating temperature characteristic at this time.

FIG. 15 shows still another embodiment of the heat treatment apparatus according to the present invention. The heat treatment apparatus according to the present embodiment has a high-temperature heating furnace 80. The high-temperature heating furnace 80 is a continuous heating furnace, in which a plurality of main heating tanks 51 are provided in a preheating tank 52, and a plurality of preheating tanks 52 are provided. Partitioned to correspond to 1. According to such a configuration, it is possible to set the temperature of the main heating tank 51 to be different from each other, to perform the processing in each main heating tank 51 according to each process, and to continuously give a different heat history to the sample 56. And In addition, the improvement in mass productivity is remarkable compared to batch processing.

The heat treatment apparatuses described in all of the above embodiments are not limited to the use of the heat treatment in the liquid crystal growth method of single crystal SiC described above.

Utilize the feature of heating to a predetermined temperature within a range of about 800 ° C or more and 260 ° C or less, preferably 120 ° C or more and 230 ° C or less in a short time. Thus, for example, after ions are implanted into the surface of the semiconductor substrate, the device is heated to a high temperature in a short time, so that the ion-implanted portion can be crystallized reliably and efficiently. The heat treatment apparatus according to the present embodiment is small and has a relatively simple structure, so that it can be easily connected to another apparatus such as an ion implantation apparatus.

Conventionally, when high-speed heating is performed, a special method such as laser or plasma has been used. However, the heat treatment apparatus according to the present embodiment has a simple structure and can be connected to another apparatus such as an electron microscope or an ion implantation apparatus. Therefore, there is a possibility that new materials that could not be obtained by the conventional method can be created.

Although the present invention has been described in the above preferred embodiments, the present invention is not limited thereto. It will be understood that various example embodiments may be made without departing from the spirit and scope of the invention.

Claims

The scope of the claims

1. A heating chamber that heats the object to be processed in a short time to a predetermined temperature within a range of about 1200 to 230 ° C,

A front chamber connected to the heating chamber and provided with a moving unit for moving an object to be processed into the heating chamber;

A preheating chamber connected to the front chamber and preheating the workpiece to a predetermined temperature;

After heating the about 8 0 0 ° C or higher in the object to be processed in advance a pressure of about 1 0- ² P a less preferably about 1 0- ⁵ P a preheating chamber of a vacuum follows, advance about 1 2 0 0 ° C or more 2 3 0 0 ° C or less pressure of about 1 that is heated to a predetermined temperature in the range of 0 _ ² P a less preferably about 1 0- ⁵ P a vacuum below, or pre-pressure of about 1 0 one ² P a or less, preferably by moving about 1 0- ⁵ P a following heating chamber under lean gas atmosphere with an inert gas is introduced after reaching the vacuum, the object to be processed was briefly A heat treatment method of heating to a predetermined temperature within a range of about 1200 ° C to 230 ° C.

2. A single-crystal silicon carbide substrate serving as a seed crystal and a polycrystalline silicon carbide substrate are stacked, placed in a closed container, and subjected to a high-temperature heat treatment to obtain the single-crystal silicon carbide substrate and the polycrystalline carbon carbide. A liquid crystal of single-crystal silicon carbide in which an ultra-thin metal silicon melt is interposed between the silicon substrate and the silicon substrate during the heat treatment and the single-crystal silicon carbide is liquid-phase epitaxially grown on the single-crystal silicon carbide substrate A heat treatment method in an epitaxial growth method,

Said sealed container, with heating to about 8 0 0 ° C or higher in advance a pressure of about 1 0- ² P a less preheating chamber, under reduced pressure the closed container below the pressure of about 1 0- ⁵ P a, advance about 1 4 0 0 ° C over 2 3 0 0 ° C following the pressure which has been heated to a predetermined temperature in the range from about 1 0- ² P a or less, preferably about 10_ ⁵ Pa or less vacuum, or pre-pressure about 1 0 ⁵ to introduce an inert gas after reaching below P a dilute The single crystal silicon carbide substrate and the polycrystalline silicon carbide substrate can be moved to a temperature of about 140 ° C. or more in a short time by moving to a heating chamber under a thin gas atmosphere. is heated to a predetermined temperature within a temperature range below not exist fine grain boundaries, microphone port pipe defect density of the surface to produce a single crystal carbonization Kei arsenide is about 1 Z cm ² or less single crystal Heat treatment method in liquid phase epitaxial growth of silicon carbide.

3. When the closed container is moved to the heating chamber, no temperature difference is provided in the axial direction of the closed container, a temperature gradient is provided in the in-plane direction of the closed container, and the temperature gradient is arbitrarily controlled. 3. The heat treatment method in a liquid phase epitaxial growth method for single crystal silicon carbide according to claim 2, wherein the generation of fine crystal grain boundaries is suppressed by performing the method.

4. The heat treatment method according to claim 2, wherein the closed container is formed of either tantalum or tantalum carbide in a liquid-phase epitaxial growth method of single-crystal silicon carbide.

5. The closed container is formed of an upper container and a lower container, and the pressure in the closed container is higher than the pressure in the heating chamber to such an extent that silicon vapor leaks from the fitting portion of the upper container and the lower container. 3. The heat treatment method in a liquid-phase epitaxy method for growing single-crystal silicon carbide according to claim 2, wherein the control is performed so that impurities are mixed into the closed container.

6. The liquid-phase epitaxial growth method for single-crystal silicon carbide according to claim 2, wherein a contaminant removal mechanism for physically adsorbing silicon vapor leaking from the closed vessel is provided in the heating chamber. Heat treatment method.

7. The surface of the single-crystal silicon carbide has an atomic order step having a minimum of three molecular layers, and a wide terrace, and the width of the terrace is about 10 μητ_ or more. 3. The heat treatment method according to claim 2, wherein the single crystal silicon carbide is a liquid phase epitaxial growth method.

8. The heat treatment method according to claim 7, wherein the surface is a (001) Si plane.

9. The heat treatment method according to claim 2, wherein said ultra-thin metal silicon melt has a thickness of about 50 / im or less.

1 0. Treatment object below a pressure of about 1 CT ² P a, preferably preferably to less than about 1 ^'0-5 P a hereinafter the vacuum, or pre-pressure of about 1 0 ² P a about 1 0 ⁵ After reaching a vacuum of Pa or less, the mixture is heated to a temperature range of about 1200 to 230 ° C in a short time in a rare gas atmosphere in which an inert gas is introduced. ,

A reserve heat port, which is connected to the front chamber and heats the object to be heated to about 800 ° C. or more in advance in a vacuum of about 10 to ² Pa or less, preferably about 1 CT ⁵ Pa or less. Equipped heat treatment equipment.

11. The heat treatment apparatus according to claim 10, wherein the heating unit of the preheating chamber is a ramp-type heating unit.

1 2. The interior of the vacuum high-temperature furnace is composed of two or more separate tanks, and the insides of the multiple tanks are composed of a main heating tank and a preheating tank, and the preheating tank is mainly adsorbed to the sample. It is heated from room temperature to about 800 ° C for degassing of gas and gas contained in the sample, and after degassing, it is heated and evacuated beforehand, and the main heating tank which is kept at a clean high temperature is The main heating tank is moved quickly, and the main heating tank always reaches a pressure of about 10 -3 Pa or less, or once reaches a pressure of about 10-3 Pa or less, and then introduces some inert gas. , Is constantly heated to a predetermined high temperature within a range of about 800 ° C. or more and 260 ° C. or less under a rare gas atmosphere at an arbitrary pressure from atmospheric pressure to about 10 −3 Pa, The preliminary The heat tank has a function that can be evacuated from the atmospheric pressure for loading and unloading the sample to the same pressure as the main heating tank required to move the sample to and from the main heating tank. After preheating the sample to a temperature of about 800 ° C, it is moved to the main heating tank quickly, so that the optimal processing temperature of the sample is within the temperature range of about 800 ° C or more and 260 ° C or less. A heat treatment apparatus characterized by having a high-temperature heating furnace that quickly achieves a high-temperature and high-purity atmosphere.

1 3. A high-purity high-temperature furnace with a processing temperature of the above-mentioned main heating tank of about 1200 ° C or more and 260 ° C or less, and the heating part of the high-temperature furnace is a high melting point metal of W or Ta. The heat-reflecting and heat-retaining region surrounding the high-temperature region has a composite structure composed of a refractory metal selected from W, Ta, and Mo. An infrared reflective film having an arbitrary wavelength range within a range of about 0.4 or more and about 3.5 / zm or less is formed on the surface of the refractory metal of the material, the wavelength reflecting the emission wavelength range of the heat generating portion being about 0.4 to about 3.5 / zm. The heat treatment apparatus according to claim 12, further comprising a high-temperature heating furnace.

14. The heat insulation area composed of a high melting point metal plate surrounding the heater part of the main heating tank has a composite structure consisting of a heat insulation layer and a heat ray reflection layer, and each layer has a function of holding high temperature and reflecting heat rays. The surface of the high melting point metal plate that constitutes the heat retaining area is made of a highly heat-resistant metal carbide such as WC, TaC, MoC, ZrC, HfC, BN, or metal nitride alone , Or a composite that has the function of preventing deterioration and deformation of the refractory metal, and that the surface of the refractory metal serving as the heat ray reflective layer is covered with an infrared reflective film such as Au. The method according to claim 12, further comprising a high-temperature heating furnace having a function of efficiently reflecting an arbitrary emission wavelength range in a range of about 0.4 to 3.5 m. Heat treatment equipment.

15 5. The vacuum high-temperature furnace is divided into a main heating tank and a preheating tank in order to rapidly heat the sample, and each room is maintained in order to maintain a high-purity atmosphere. Can be maintained in an independent vacuum evacuation system, or in an independent gas introduction system, and at atmospheric pressure, and the main heating tank and preheating tank can be integrated and separated by opening and closing the shutoff valve. In a heat treatment apparatus with a high-speed high-temperature heating furnace maintained mutually,

When the main heating tank reaches a pressure of about 10 -3 Pa or less during normal use, or once reaches a pressure of about 10 -3 Pa or less, a small amount of inert gas is introduced, and the pressure is reduced from atmospheric pressure to about 10 -3 Pa. It is maintained at a high temperature within a temperature range of about 800 ° C or more and 260 ° C or less in a rare gas atmosphere at an arbitrary pressure up to 10-3 Pa. Built-in cold trap for adsorbing built-in gas generated from samples, etc., when the temperature is maintained in the temperature range of about room temperature or more and 100 ° C. or less, quickly cooling from high temperature after heating to room temperature A heat treatment apparatus comprising a high-temperature heating furnace having a built-in quenching gas circulation device for performing the cooling.

16. The heating source of the preheating tank has a reflecting mirror to focus near infrared rays on the sample in order to rapidly heat it in a short time. The heat treatment apparatus according to claim 15, further comprising a high-temperature heating furnace that is an infrared heating lamp to which a generation function film is added. '

17. The method according to claim 15, wherein the heating portion of the main heating tank has a high-temperature heating furnace including a cylindrical main heater made of a high-melting-point metal and a planar auxiliary heater. Heat treatment equipment.