JP2015030648A - Hexagonal boron nitride, heater, and production method hexagonal boron nitride - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide hexagonal boron nitride excellent in mechanical strength and having conductivity.SOLUTION: The hexagonal boron nitride comprises nitrogen, boron, and a heterogeneous element introduced as a dopant into a crystalline structure composed of nitrogen and boron. The heterogeneous element comprises one or more elements selected from a group consisting of group-1 elements and group-2 elements, or one or more elements selected from a group consisting of group-14 elements and group-16 elements excluding oxygen. A content ratio of the heterogeneous element is 1 ppm by mass or more and 6×10ppm by mass or less.

Description

  The present invention relates to hexagonal boron nitride, a heater using the hexagonal boron nitride, and a method for producing the hexagonal boron nitride.

  Hexagonal boron nitride is a layered crystal similar to graphite, in which hexagonal mesh planes in which boron atoms (B) and nitrogen atoms (N) are alternately covalently bonded are loosely bonded to each other by van der Waals forces and stacked. It is a solid substance having a structure. Hexagonal boron nitride is superior in properties such as thermal conductivity, heat resistance, corrosion resistance, chemical stability, mechanical strength, lubricity, and is electrically insulating unlike graphite. In powder form, it is used as a solid lubricant, heat-resistant release material, resin or rubber filler. Further, hexagonal boron nitride is used as a compound semiconductor growing crucible, an electrical insulating material, various electronic materials and the like.

  For example, in Japanese Patent Laid-Open No. 2001-23759 (Patent Document 1), in a heater for a vapor phase growth apparatus using graphite as a heating element, graphite is coated with pyrolytic boron nitride, and the surface of the graphite is electrically Insulating and protecting from mechanical damage. In Patent Document 1, pyrolytic boron nitride, which is hexagonal boron nitride, is used as a coating material, and the electrical insulation properties and excellent mechanical strength characteristics of hexagonal boron nitride are utilized.

JP 2001-23759 A

  However, the heater described in Patent Document 1 has a problem in that peeling tends to occur on the contact surface because the thermal expansion coefficient differs between graphite and boron nitride. In addition, there is a problem that the graphite and boron nitride react at a high temperature and the heater melts. In hexagonal boron nitride, if conductivity can be imparted without degrading mechanical strength and other properties, hexagonal boron nitride can be used as a heating element instead of graphite, preventing peeling and melting. Heaters can be provided.

  The present invention has been made in view of the above problems, and has excellent mechanical strength and conductivity. Hexagonal boron nitride, a heater using the hexagonal boron nitride, and a method for producing the hexagonal boron nitride The purpose is to provide.

The present invention includes nitrogen, boron, and a heterogeneous element doped in a crystal structure composed of nitrogen and boron, and the heterogeneous element is one selected from the group consisting of a group 1 element and a group 2 element It is one or more elements selected from the group consisting of the above elements, or Group 14 elements other than Group 14 elements and oxygen, and the content of different elements is 1 mass ppm or more and 6 × 10 ⁴ mass ppm or less Provide hexagonal boron nitride.

  Further, the present invention comprises a heating element comprising the above hexagonal boron nitride, a power supply source for supplying electricity to the heating element, and a covering material comprising the insulating hexagonal boron nitride and covering the heating element, Provided is a heater in which electricity is supplied from a power supply source to a heating element to generate heat.

  The present invention is also a method for producing the above hexagonal boron nitride, wherein the hexagonal boron nitride is formed by a chemical vapor deposition method using a nitride gas, a boron compound gas, and a gas containing a different element. A method for producing hexagonal boron nitride is provided.

  According to the present invention, hexagonal boron nitride having excellent mechanical strength and conductivity can be provided.

It is sectional drawing which shows an example of the heater which used the hexagonal boron nitride for the heat generating body. It is a perspective view which shows an example of the state which formed the hexagonal boron nitride on the base material.

[Description of Embodiment of the Present Invention]
One embodiment of a hexagonal boron nitride according to the present invention (hereinafter, hexagonal boron nitride is also referred to as “hBN”) is a heterogeneous element doped in nitrogen, boron, and a crystal structure composed of nitrogen and boron. And the heterogeneous element is one or more elements selected from the group consisting of Group 1 elements and Group 2 elements, or one or more elements selected from the group consisting of Group 14 elements and Group 16 elements other than oxygen It is an element, and the content rate of a different element is 1 mass ppm or more and 6 × 10 ⁴ mass ppm or less. Such hBN can impart conductivity by the addition of the different elements as described above, and since the different elements are added to be doped in the crystal structure, the mechanical strength is reduced. Can be suppressed.

  The volume resistivity of the hBN is preferably 100 mΩcm or less. By having such a volume resistivity, for example, it can be used as a heating element that generates heat by resistance heating by supplying electricity thereto.

  The hBN is preferably a polycrystal, and the grain size of the single crystal constituting the polycrystal is preferably 10 nm or more and 500 nm or less. By having such a particle size, the isotropic property can be improved and the mechanical strength can be improved.

  An embodiment of the heater according to the present invention includes a heating element made of hBN, a power supply source for supplying electricity to the heating element, and a covering material made of insulating hexagonal boron nitride and covering the heating element. And a configuration in which electricity is supplied from the power supply source to the heating element to generate heat. In the heater having such a configuration, the heating element is covered with a coating material having an insulating property and high mechanical strength, and the coating material and the heating element are made of the same material. Since it can suppress peeling and reaction, it has a long life.

  One embodiment of the method for producing hBN according to the present invention includes a step of forming hBN by chemical vapor deposition using a nitride gas, a boron compound gas, and a gas containing a different element. The different elements can be added by dissolving the different elements in hBN. However, in such a method, the different elements are clustered and the mechanical strength is lowered or the conductivity can be imparted. Addition may be difficult. In this embodiment, the polycrystalline hBN in which the different elements are doped in the crystal structure is manufactured by the chemical vapor deposition method using the nitride gas, the boron compound gas, and the gas containing the different elements. Therefore, it is possible to add a uniform different element without reducing the mechanical strength, and the conductivity can be imparted without lowering the mechanical strength.

[Details of the embodiment of the present invention]
Hereinafter, the hBN, the heater, and the method for manufacturing hBN of the embodiment of the present invention will be described in more detail.

<Hexagonal boron nitride (hBN)>
The hBN of this embodiment includes nitrogen (N), boron (B), and a heterogeneous element doped in a crystal structure composed of nitrogen and boron.

  In this specification, “a heterogeneous element doped in a crystal structure” means that a heterogeneous element is substituted with a part of nitrogen or boron in the crystal structure of hBN formed by covalently bonding nitrogen and boron. In other words, in other words, a state in which it is present in a state of being covalently bonded to nitrogen and boron constituting the crystal structure and dispersed in the crystal structure at the atomic level. The hBN of this embodiment preferably does not contain clustered heterogeneous elements. A cluster is a state in which a plurality of atoms are aggregated and exist in a crystal structure, and is different from a state in which they are dispersed and present at an atomic level in the crystal structure. When a clustered heterogeneous element is included, the heterogeneous element exists non-uniformly in the crystal structure, reducing the homogeneity of hBN and causing a large distortion in the crystal structure, resulting in the mechanical strength of hBN. Is not preferable.

  The structure of hBN may include a single crystal in a part and the other part may be amorphous or indefinite, or may be a polycrystal composed of a single crystal, but has a high mechanical strength. From the point of view, it is preferably a polycrystal.

  Whether or not a different element is contained in hBN and the content thereof can be measured by inductively coupled plasma (ICP) analysis, secondary ion mass spectrometry (SIMS). When the heterogeneous element is contained in hBN, whether the heterogeneous element is dispersed in the crystal structure at the atomic level can be determined by, for example, (1) observing whether a crystal phase of the heterogeneous element exists in hBN. , (2) by measuring the atomic concentration distribution of different elements in hBN, (3) by measuring the presence or absence of conductivity of hBN, and appropriately combining the above (1) to (3) and other methods Can be confirmed.

  Regarding the above (1), since the different element dispersed in the crystal structure at the atomic level does not form a crystal phase different from hBN, the crystal phase of the different element is not observed. On the other hand, since the different elements present in a cluster form a crystal phase different from that of hBN, a crystal phase of the different elements is observed. The presence or absence of such a crystal phase can be observed by, for example, an X-ray diffraction spectrum, and can also be visually observed depending on the size of the crystal phase.

  Regarding (2) above, when the different elements are dispersed in the crystal structure at the atomic level, the atomic concentration distribution of the different elements is uniform as compared to the case where the different elements exist in a clustered state. Such an atomic concentration distribution can be measured by, for example, secondary ion mass spectrometry (SIMS). When the difference in atomic concentration of different elements measured at two arbitrary points in the crystal structure is less than or equal to a predetermined value, the atomic concentration distribution of the different elements can be considered to be uniform. It can be considered that it is in a state dispersed in the crystal structure and not in a clustered state.

  Regarding (3) above, for example, for hBN, it is confirmed by the X-ray diffraction spectrum that there is no crystal phase of a different element, and the volume resistivity (Ωcm) of hBN is measured to confirm conductivity. When the crystal phase of the different element is not confirmed and the volume resistivity is not more than a predetermined value, it can be considered that the different element is dispersed in the crystal structure at the atomic level.

  The heterogeneous element doped in hBN of this embodiment is selected from one or more elements selected from the group consisting of Group 1 elements and Group 2 elements, or from the group consisting of Group 14 elements and Group 16 elements other than oxygen. One or more elements. The group 1 element and the group 2 element have no electrons in the outermost p-orbital, and therefore can function as an acceptor and impart conductivity to hBN. Examples of the group 1 element include lithium (Li), and examples of the group 2 element include beryllium (Be) and magnesium (Mg). The group 14 element and the group 16 element can impart conductivity to the hBN by donating electrons in the outermost p-orbital as a donor. Examples of the group 14 element include carbon (C) and silicon (Si), and examples of the group 16 element include sulfur (S).

  HBN of this embodiment is selected from the group consisting of one or more acceptor elements selected from the group consisting of Group 1 elements and Group 2 elements, or the group consisting of Group 14 elements and Group 16 elements other than oxygen as the different elements. One or more kinds of donor elements are included, and a plurality of acceptor elements may be included, and a plurality of donor elements may be included.

In the hBN of the present embodiment, the content of different elements is 1 mass ppm or more and 6 × 10 ⁴ mass ppm or less. When the content of the different element is less than 1 ppm by mass, it is difficult to impart conductivity, and when it exceeds 6 × 10 ⁴ ppm by mass, it is difficult to obtain sufficient mechanical strength. In addition, in the above numerical range, sufficient heat can be generated by resistance heating with electricity flowing, so that the material is useful as a heating element. The content of the different elements is preferably 1000 ppm by mass or more and 100000 ppm by mass or less.

  In the present specification, the content of different elements is a value measured by ICP analysis. In the hBN of the present embodiment, since different elements are uniformly dispersed regardless of the content rate, it is possible to suppress local variations in characteristics in the hBN.

  The hBN of the present embodiment has a volume resistivity of preferably 100 mΩcm or less, more preferably 10 mΩcm or less. When the volume resistivity is 100 mΩcm or less, electric discharge machining is easy, and efficient machining and precise machining can be performed by electric discharge machining. In this specification, the volume resistivity is a value measured according to JIS C2141.

  The hBN of the present embodiment is preferably a polycrystal, and the grain size (maximum length of crystal grains) of the single crystal constituting the polycrystal is preferably 1 μm or less, more preferably 10 to 500 nm. is there. When the grain size of the single crystal is 500 nm or less, the isotropic property is improved, the polycrystalline hBN which is not easily chipped and has excellent mechanical strength is obtained. It is preferable that the single crystal constituting the polycrystalline hBN has a small variation in particle size, and the number of particles having a particle size exceeding twice the average particle size of the particles constituting the entire crystal is preferably less than 20%. . When the variation in the particle diameter is within the above range, the isotropy is further improved, and polycrystalline hBN excellent in mechanical strength is obtained.

  The hBN of the present embodiment can be manufactured by a method for manufacturing hBN, which will be described later. According to this manufacturing method, particles can be firmly bonded to each other without interposing a binder between single crystal particles. it can. In addition, when particles are bonded with a binder, the mechanical strength of hBN is reduced, but the hBN of the present embodiment can be configured without intervening binder, and thus has high mechanical strength. .

Moreover, according to the manufacturing method mentioned later, hBN with a sufficiently low amount of inevitable impurities can be manufactured. Specifically, in the hBN of the present embodiment, the content of each element that is an inevitable impurity can be set to 1 × 10 ³ mass ppm or less, further 1 × 10 ² mass ppm or less. When the content of each element that is an inevitable impurity is 1 × 10 ³ mass ppm or less, slip at the single crystal grain boundary can be suppressed, and the bond between the single crystal grains can be made stronger. Therefore, the mechanical strength of hBN can be further increased. Therefore, in the hBN of this embodiment, the content of each element that is an inevitable impurity is preferably 1 × 10 ³ mass ppm or less, and more preferably 1 × 10 ² mass ppm or less. The inevitable impurities mean nitrogen, boron, and elements other than the intended different elements, and examples thereof include hydrogen (H), oxygen (O), silicon (Si), and transition metals.

The content of each element of inevitable impurities can be measured by ICP analysis or SIMS analysis. Since the detection limit by these analytical methods is about 1 × 10 ² mass ppm, it is preferable that inevitable impurities are not detected by these analytical methods.

  Further, the hBN of the present embodiment is useful as a heater heating element, a structure, a support, and a heat insulating material because it has high mechanical strength and conductivity.

<Heater>
FIG. 1 is a cross-sectional view showing an embodiment of a heater including a heating element made of hBN. In the heater of this embodiment, the heating element 11 is made of conductive hBN according to the present invention, and a part of the surface of the heating element 11 is covered with a covering material 12 made of insulating hBN. The heating element 11 is connected to a power supply source (not shown) and is configured such that the heating element generates heat by resistance heating when electricity is supplied from the power supply source to the heating element. In the heater, the object to be heated is placed in the space 13 and heated.

  Since the hBN according to the present invention used for the heating element 11 has high mechanical strength and conductivity, it generates heat by resistance heating. In addition, since the heating element 11 and the covering material 12 covering the heating element 11 are formed of the same hBN, although the characteristics are different, the thermal expansion coefficient between these materials is the same and is difficult to peel off. Long life without chemical reaction between materials. Such a heater can maintain the temperature of the heating element at a high temperature of 1800 to 2000 ° C., for example. Such a heater can be used as a heater for chemical vapor deposition, for example.

<Method for producing hexagonal boron nitride (hBN)>
The method for manufacturing hBN of this embodiment includes a step of forming hBN by chemical vapor deposition using a nitride gas, a boron compound gas, and a gas containing a different element. The produced hBN includes nitrogen, boron, and a heterogeneous element doped in a crystal structure composed of nitrogen and boron, and the heterogeneous element is selected from the group consisting of a group 1 element and a group 2 element One or more elements, or one or more elements selected from the group consisting of Group 14 elements and Group 16 elements other than oxygen, and the content of different elements in hBN is 1 mass ppm or more and 6 × 10 ⁴ mass ppm or less.

As shown in FIG. 2, the step of forming hBN includes nitrogen, boron, and a heterogeneous element doped in a crystal structure composed of nitrogen and boron. One or more elements selected from the group consisting of elements, or one or more elements selected from the group consisting of group 14 elements other than group 14 elements and oxygen, and the content of different elements in hBN is 1 HBN1 having a mass ppm of 6 × 10 ⁴ mass ppm or less is formed on the substrate 2. Such hBN can be formed on a substrate by using, for example, the following chemical vapor deposition (CVD) method.

(CVD method)
First, the base material 2 for vapor-phase growing hBN is arranged on the main surface in the vacuum chamber. As a material of the base material 2, any metal, inorganic ceramic material, carbon material, and boron nitride material may be used as long as they can withstand a temperature of about 1400 ° C. to 2300 ° C. From the viewpoint of reducing impurities mixed in hBN, it is preferable that at least the main surface of the base material is a boron nitride material.

  Next, the base material 2 disposed in the vacuum chamber is heated at a temperature of about 1400 ° C. to 2300 ° C. As a heating method, a known method can be adopted. For example, a method of installing a heater capable of directly or indirectly heating the substrate 2 in a vacuum chamber can be mentioned.

  Next, a nitride gas, a boron compound gas, and a gas containing a different element are introduced into the vacuum chamber. At this time, the degree of vacuum (pressure) in the vacuum chamber is set to atmospheric pressure or lower. As a result, the nitride gas, the boron compound gas, and the gas containing the different element can be uniformly mixed in the vacuum chamber.

As the nitride gas, ammonia, 4,4′-diaminodiphenyl sulfone, or the like can be used, and ammonia is preferably used from the viewpoint of preventing contamination by oxygen. As the boron compound gas, for example, a boron halide such as boron trichloride (BCl ₃ ), an organic boron compound, or a combination thereof can be used. As the gas containing a different element, it is preferable to use a gas composed of a hydride of a different element or a hydrocarbon gas containing a different element. When a gas composed of a hydride of a different element is used, the gas can be easily decomposed at a high temperature, so that the different element can be efficiently supplied onto the substrate.

For example, when S is doped as a different element, it is preferable to use hydrogen sulfide (H ₂ S), dimethyl sulfide (C ₂ H ₆ S), etc., and when C is doped, dimethylamine, triethylamine, It is preferable to use a hydrocarbon or the like. When Si is doped, silane or the like is preferably used. When Li is doped, alkyllithium or the like is preferably used. When Be is doped, A method of directly vaporizing at a high temperature is preferably used. When Mg is doped, an organic magnesium compound or the like is preferably used.

  Then, by pyrolyzing the mixed gas at a temperature of 1400 ° C. or higher, nitrogen, boron, and a heterogeneous element doped in a crystal structure composed of nitrogen and boron are formed on the main surface of the substrate. In other words, hBN1 is formed in which different elements are dispersed in the crystal structure at the atomic level.

  In the above CVD method, the degree of vacuum is set to 200 Torr or less in order to make the grain size of the single crystal contained in hBN1 10 nm or more and 500 nm or less. The structure of hBN1 may be a structure in which a single crystal is included in part and the other part is amorphous or indefinite, or may be a polycrystal composed of a single crystal. In order to obtain polycrystalline hBN having a more uniform particle size, it is preferable to form hBN1 having a (111) half-value line width of 0.21 ° or more in X-ray diffraction.

Further, in the above CVD method, the mixing ratio of the nitride gas, the boron compound gas, and the gas containing the different element in order to make the content of the different element in hBN1 1 ppm or more and 6 × 10 ⁴ ppm by mass or less. Adjust. Regarding the mixing ratio of the nitride gas and the boron compound gas, it is preferable that the difference in atomic concentration between nitrogen and boron is 10% or less. For a gas containing a different element, the content of the different element in hBN1 can be increased by increasing the mixing ratio. Moreover, the content rate of a different element can also be adjusted by changing the kind of gas containing a different element.

In this step, by using the above-mentioned CVD method, hBN containing nitrogen, boron, and a heterogeneous element doped in a crystal structure composed of nitrogen and boron on a substrate, HBN having a content of 1 ppm by mass to 6 × 10 ⁴ ppm by mass is formed.

  In addition, regarding hBN prepared in this step, the heterogeneous element is uniformly doped in both the thickness direction and the in-plane direction, that is, the atomic concentration distribution of the heterogeneous element in hBN is uniform. preferable. Since the heterogeneous element is uniformly doped in hBN, hBN having no variation in characteristics can be configured.

  In order to make the atomic concentration distribution of the different elements uniform, it is preferable to introduce the nitride gas, the boron compound gas, and the gas containing the different elements into the vacuum chamber at the same time. Thereby, each gas can be easily and uniformly mixed, and hBN in which different elements are uniformly doped can be efficiently generated on the substrate. Each gas may be supplied from the direction directly above the main surface of the base material toward the main surface of the base material, and supplied from the oblique direction or the horizontal direction to the base material toward the base material. May be. From the viewpoint of more efficiently and more uniformly doping a different element, it is preferable to supply from the direction directly above the main surface of the base material toward the main surface of the base material. Further, in order to more efficiently and more uniformly dope different elements, a guide for guiding the nitride gas, the boron compound gas, and the gas containing the different elements onto the main surface of the substrate in the vacuum chamber. A member may be provided.

The density of hBN prepared in this step is preferably 1.4 g / cm ³ or more and 2.1 g / cm ³ or less. When the hBN density is 1.4 g / cm ³ or more, sintering can be successfully achieved with a yield of 50% or more.

  The density of hBN can be adjusted by, for example, the temperature (° C.) at which hBN is grown on the main surface of the substrate and the introduction rate (ml / min) of each gas. Specifically, the density of hBN can be increased by increasing the temperature and increasing the introduction rate of each gas.

Moreover, regarding the hBN prepared in this step, the content of inevitable impurities is preferably low. Specifically, the content of each element that is an inevitable impurity is 1 × 10 ³ mass ppm or less. preferable. By keeping the content of inevitable impurities low, grain growth due to the presence of inevitable impurities can be suppressed, so that a single crystal having a more uniform size can be contained in hBN. In addition, since the detection limit is generally 1 × 10 ² mass ppm or less, an analysis apparatus used for analysis capable of measuring the content of inevitable impurities in hBN such as ICP analysis and SIMS analysis has a content rate of 1 × 10 ² mass ppm or less. An element of 1 × 10 ² mass ppm or less is not detected by the analyzer.

Mixing of inevitable impurities into hBN can be suppressed by setting the degree of vacuum in the vacuum chamber when the gas is pyrolyzed relatively high. Normally, when hBN is formed by CVD, the degree of vacuum in the vacuum chamber is maintained at about 100 Torr to 150 Torr, but the present inventors maintain unavoidable impurities by maintaining this degree of vacuum at about 10 Torr to 90 Torr. It has been found that the content of each element can be controlled to 1 × 10 ³ mass ppm or less.

  In the above CVD method, the method of introducing the mixed gas into the vacuum chamber after heating the base material has been described. However, the method of heating the base material after introducing the mixed gas may be used, and simultaneously performed. May be.

According to the hBN manufacturing method of the present embodiment described in detail above, hBN having the above-described characteristics, that is, including nitrogen, boron, and a heterogeneous element doped in a crystal structure composed of nitrogen and boron. The heterogeneous element is one or more elements selected from the group consisting of Group 1 elements and Group 2 elements, or one or more elements selected from the group consisting of Group 14 elements and Group 16 elements other than oxygen. Thus, it is possible to produce polycrystalline hBN having a content of different elements of 1 mass ppm or more and 6 × 10 ⁴ mass ppm or less. Such polycrystalline hBN cannot be produced by conventional techniques.

  Moreover, according to the manufacturing method of this embodiment, since hBN is formed so that dissimilar elements are uniformly dispersed, it is possible to effectively suppress local abnormal growth of crystal grains constituting hBN. it can. Thereby, the grain size of the single crystal constituting hBN can be made more uniform, and as a result, homogeneous hBN having the above characteristics can be produced.

  In Examples 1 to 3, as described in detail below, hBN was prepared by a CVD method, and for the obtained hBN, measurement of the grain size of a single crystal and measurement of the content of different elements by the following method, The volume resistivity was measured.

<Measurement of grain size of single crystal>
The particle size of each single crystal in an SEM (Scanning Electron Microscopy) image obtained using an electron microscope was measured.

<Measurement of content of different elements>
The content of each element was measured using an ICP-MS analyzer.

<X-ray diffraction measurement>
An X-ray diffraction spectrum was obtained using an X-ray diffractometer.

<Measurement of volume resistivity>
The volume resistivity at a temperature of 20 ° C. was measured with a resistivity meter.

<Example 1>
First, a base material made of pyrolytic boron nitride was placed in a vacuum chamber. Next, the substrate in the chamber is heated with a 1500 ° C. graphite heater, and the degree of vacuum (pressure) in the vacuum chamber is 10 Torr. Boron trichloride is 100 sccm, ammonia is 100 sccm, and hydrogen sulfide is contained in the vacuum chamber. Feeding was continued for 1 hour at 2 sccm. Thereby, hBN doped with sulfur having a thickness of about 100 μm was formed on the main surface of the substrate.

  Thereafter, the supply of boron trichloride, ammonia, and hydrogen sulfide was continued at the same supply amount, and finally hBN doped with plate-like sulfur of 50 × 50 × 20 mm was formed.

The formed hBN had a single crystal particle size of 0.1 to 1 μm, a sulfur content of 1 × 10 ⁴ ppm by mass, and a volume resistivity of 1 mΩcm.

  The heater shown in FIG. 1 was configured using hBN thus produced as a heating element and further using insulating hBN as a covering material. Even when the heater was heated up to a temperature of 2000 ° C., peeling and melting between the heating element and the covering material were not observed.

<Example 2>
HBN was formed by the same method as in Example 1 except that the pressure in the vacuum chamber was 100 Torr. When the supply of boron trichloride, ammonia and hydrogen sulfide was continued for 1 hour, sulfur-doped hBN having a thickness of about 100 μm was formed. Thereafter, the supply was continued, and finally hBN doped with plate-like sulfur of 50 × 50 × 20 mm was formed.

The formed hBN had a single crystal particle size of 0.1 to 1 μm, a sulfur content of 1 × 10 ⁴ ppm by mass, and a volume resistivity of 1 mΩcm.

  The heater shown in FIG. 1 was configured using hBN thus produced as a heating element and further using insulating hBN as a covering material. Even when the heater was heated up to a temperature of 2000 ° C., peeling and melting between the heating element and the covering material were not observed.

<Example 3>
First, a base material made of pyrolytic boron nitride was placed in a vacuum chamber. Next, the vacuum chamber is filled with nitrogen as an atmospheric gas, the substrate is heated with a graphite heater at 2000 ° C., the pressure in the vacuum chamber is 100 Torr, boron trichloride is 100 sccm, and ammonia is placed in the vacuum chamber. Supply was continued at 100 seem and hydrogen sulfide at 2 seem for 1 hour. Thereby, hBN doped with sulfur having a thickness of about 100 μm was formed on the main surface of the substrate.

  Thereafter, the supply of boron trichloride, ammonia, and hydrogen sulfide was continued at the same supply amount, and finally hBN doped with plate-like sulfur of 50 × 50 × 20 mm was formed.

The formed hBN had a single crystal particle size of 0.1 to 1 μm, a sulfur content of 1 × 10 ⁴ ppm by mass, and a volume resistivity of 1 mΩcm.

  The heater shown in FIG. 1 was configured using hBN thus produced as a heating element and further using insulating hBN as a covering material. Even when the heater was heated up to a temperature of 2000 ° C., peeling and melting between the heating element and the covering material were not observed.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 hexagonal boron nitride (hBN), 2 base material, 11 heating element, 12 coating material.

Claims (5)

Nitrogen, boron, and a heterogeneous element doped in a crystal structure composed of the nitrogen and the boron,
The heterogeneous element is one or more elements selected from the group consisting of Group 1 elements and Group 2 elements, or one or more elements selected from the group consisting of Group 14 elements and Group 16 elements other than oxygen. ,
The content of the different element is hexagonal boron nitride, which is 1 mass ppm or more and 6 × 10 ⁴ mass ppm or less.   The hexagonal boron nitride according to claim 1, having a volume resistivity of 100 mΩcm or less.   The hexagonal boron nitride according to claim 1 or 2, wherein the hexagonal boron nitride is a polycrystal, and a single crystal constituting the polycrystal has a particle size of 10 nm to 500 nm. A heating element comprising the hexagonal boron nitride according to any one of claims 1 to 3, a power supply source for supplying electricity to the heating element, an insulating hexagonal boron nitride, and the heating element. And a covering material for covering
A heater that causes electricity to flow from the power supply source to the heating element to generate heat. A method for producing hexagonal boron nitride according to any one of claims 1 to 3,
A method for producing hexagonal boron nitride, comprising a step of forming the hexagonal boron nitride by a chemical vapor deposition method using a nitride gas, a boron compound gas, and a gas containing the different element.

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