JPH09235200A - Metal film-formed inorganic crystal substance and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a metal film-formed inorganic crystal substance having a metal later stably formed in an inorganic crystal substance such as diamond, aluminum nitride or gallium arsenate in a high adhesion strength, and provide a method (metallizing method) for efficiently forming the metal layer at a low temperature. SOLUTION: This metal film-formed inorganic crystal substance in which the just overhead of the surface of a metal film-forming site of the group III-V element inorganic crystal substance or the group IV element inorganic crystal substance is covered with nitrogen atoms in the thickness of 0.5-1.0 atomic layer (monolayer) and in which a metal film layer is formed on the nitrogen atom layer. This method for producing the metal film-formed inorganic crystal substances comprises irradiating a part or the whole parts of the surface of the inorganic crystal substance with 10-260nm light in the atmosphere of the mixture of molecules containing one or both kinds of nitrogen atoms and hydrogen atoms or in an aqueous solution and subsequently subjecting the inorganic crystal substance to an electroless plating treatment to form a metal film layer on the irradiated surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal film-forming inorganic crystal material, particularly a metal film-forming inorganic material having a metal layer formed on an inorganic crystal material such as diamond, aluminum aluminum, gallium arsenide or the like with stable and high adhesive strength. The present invention relates to a crystalline substance and a method for efficiently forming the metal layer at a low temperature (metalizing method).

[0002]

2. Description of the Prior Art Metallization of inorganic ceramics such as diamond, aluminum nitride, cubic boron nitride, silicon nitride and silicon carbide having a covalent bond, or formation of electrodes on semiconductor crystals such as silicon and gallium arsenide. Forming a high-strength metal film on a group III-V group inorganic crystal or a group IV element inorganic crystal has been a more important and difficult task than in the past. As a method of forming a metal film, a vapor deposition method, an ion plating method, a sputtering method, or the like PV
D method (physical vapor deposition method) followed by high temperature heat treatment, CVD method (chemical vapor deposition method), and method of baking metal in a humidified hydrogen stream, and further above There is a method of electroless plating. In compound semiconductors such as gallium arsenide of group III-V crystals, P
The VD method is used, and it is disclosed that a tungsten layer is formed by a CVD method in Group IV diamond. However, the PVD method, the CVD method, and the like require an expensive vacuum container that requires a complicated structure. Further, in the metallizing method for ceramics, which is often used for aluminum nitride, etc.,
Although the coated metal paste is baked at a high temperature of over 000 ° C., this high temperature treatment causes problems such as adverse effects on the material and post attachment of the metal film. Among these, the electroless plating method has been conventionally known as a method capable of forming a relatively thick film at low cost, at high speed, and at low temperature. However, the wettability of these inorganic crystal substances to water is extremely poor, and almost no electroless plating can be performed by themselves. Although it is possible to perform electroless plating to some extent by pretreatment with a surfactant, there are problems that the adhesive strength with the base is low and that a film is formed even in unnecessary places.

As a means for electrolessly plating a group III-V crystal, especially an aluminum nitride crystal, a method of etching the surface with an aqueous sodium hydroxide solution and then plating is also considered. However, diamond is chemically very stable and such chemical treatment cannot be applied. For diamond, a method of irradiating an excimer laser on the diamond surface in an electroless plating solution to form palladium nuclei on the surface and performing electroless plating has also been considered ["Ceramics Association Magazine" 95 [ 3] 1987,
p. 351]. Alternatively, a method of etching a diamond surface with a laser to roughen the surface to facilitate plating is also known. Furthermore, after forming a film of an organic silane compound having an amino group on silicon or diamond by coating or the like, the organic molecule part is removed by mask irradiation with an excimer laser or the like, and the unirradiated part of the organic molecule film is removed. Pattern formation of electroless plating layer is also being considered [WJ Dressick et al., "Jpn. J. A.
ppl. Phys., "Vol.32 (1993), pp. 5829-5839].
Irradiation of excimer laser light with a dilute aqueous ammonia solution on a fluororesin can impart high hydrophilicity to the surface, which causes desorption of fluorine and introduction of oxygen and nitrogen by photochemical reaction on the surface. It is reported to be because of this. [Collection of Polymers, Vol. 52, No.1, pp66-68
(Jan., 1955)]. Similarly, chemical surface modification of fluororesin film such as tetrafluororesin was carried out in hydrazine gas photodecomposed by ArF excimer laser irradiation to reduce the contact angle with water from 130 ° to 30 °. . It has been reported that an amino group is introduced on the surface, which imparts hydrophilicity and enables electroless plating of nickel ["Appl. Phys. Lett." 63 (25), 1993]. On the other hand, a method has also been devised in which a metal film that reacts with these base materials is deposited on the first layer and a desired metal film is further formed thereon. For example, in diamond, it has been disclosed that a titanium metal film is formed as the first layer and a carbonized layer is formed at the interface with the diamond to firmly bond them (Japanese Patent Laid-Open No. 60-155600). Gazette). Further, for diamond, a method of forming a thin metal layer and then irradiating with a laser and baking at a low temperature is disclosed (Japanese Patent Publication No. 61-10434), but basically, it reacts with diamond such as titanium and hafnium. Limited to metal.

In the above known method, diamond,
Aluminum nitride, cubic boron nitride, silicon nitride,
Metallization of inorganic ceramics of covalently bonded crystals such as silicon carbide, formation of electrodes on semiconductor crystals such as silicon and gallium arsenide, group III-V group inorganic crystals, or group IV element inorganic crystals The problem in forming a metal film is adhesiveness, but sufficient adhesive strength has not yet been obtained. As a method of increasing the adhesion strength, a method of creating an anchor effect by making unevenness on the surface by etching using laser or chemical corrosion not only lowers the processing accuracy of the surface, but also creates and modifies a gap at the interface. The physical properties are deteriorated due to the formation of the layer. Also,
It has been proposed to increase the adhesion strength by forming a reaction layer at the interface with the metal, but this also forms an altered layer at the interface, which adversely affects the characteristics. Further, since the altered layer and the metal layer have an interface, the mechanical strength is not always guaranteed.
In addition, this method can be applied only to a metal that is reasonably reactive with the underlying material and requires high temperature treatment, and cannot be applied to all metals and materials. When using the metal coating produced by these methods as a heat sink, the thermal conductivity deteriorates, and
When it is used as an electrode, it cannot be denied that it adversely affects the electrical characteristics and the ohmic characteristics of the junction.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in order to solve various problems in the above-mentioned known method, and in terms of surface accuracy of the surface, a metal film is formed on the surface as mirror-polished. An object of the present invention is to provide a metal film forming method at low temperature and a metal film formed product that can be formed, has adhesiveness on an atomic order, has high mechanical strength, excellent ohmic characteristics, and heat conduction characteristics.

[0006]

[Means for Solving the Problems] The above object is to irradiate the surface of an inorganic crystalline material with light having a wavelength of 10 to 260 nm in a gas atmosphere or an aqueous solution containing nitrogen and hydrogen, and then by electroless plating. It has been found to be achieved by forming a metal coating layer on the surface.

The matters specified by the present invention will be listed below. (1) 0.5 atomic layer (= monolayer) or more and 1 atomic layer immediately above the surface of the portion of the periodic table group III-V inorganic crystalline material or group IV element inorganic crystalline material forming the metal film A metal film-forming inorganic crystal substance characterized in that it is at least covered with the following nitrogen atoms, and a metal film layer is formed on the nitrogen atom layer. (2) The inorganic crystalline substance is at least selected from the group consisting of diamond, silicon, germanium, cubic boron nitride, aluminum nitride, silicon nitride, silicon carbide, gallium arsenide, indium phosphide, gallium nitride, and solid solutions and compounds thereof. The metal film-forming inorganic crystal substance according to (1) above, which is one kind. (3) The metal according to (1) above, wherein the metal film layer is made of at least one selected from the group consisting of gold, aluminum, tin or alloys thereof, and nickel, iron, cobalt or alloys thereof. Film-forming inorganic crystalline substance.

(4) In the method for forming a metal film on a group III-V inorganic crystal substance or a group IV element inorganic crystal substance of the periodic table, a molecule containing both a nitrogen atom and a hydrogen atom, or one of them. After irradiating the entire surface or a part of the surface with light in the range of 10 nm or more and 260 nm or less in a mixed atmosphere of molecules containing each of the above or an aqueous solution, a metal film layer is formed on the surface by electroless plating. A method for producing a metal film-forming inorganic crystalline material, comprising: (5) The metal film-forming inorganic crystalline substance according to (4) above, which is brought into contact with a fluorine gas to fluorinate all or part of the surface of the inorganic crystalline substance before irradiation with light. Production method. (6) The method for producing a metal film-forming inorganic crystal substance according to the above (4) or (5), wherein the molecule containing the nitrogen element is ammonia. (7) The irradiation light is any one of excimer laser light, excimer lamp light, low-pressure mercury lamp light, synchrotron radiation light, and synchrotron radiation undulator light. The manufacturing method of the metal film formation inorganic crystalline substance in any one of 1). (8) The method for producing a metal film-forming inorganic crystal substance according to any one of the above (4) to (7), which is an excimer laser having an oscillation wavelength of 193 nm.

(9) The inorganic crystalline substance is selected from the group consisting of diamond, silicon, germanium, cubic boron nitride, aluminum nitride, silicon nitride, silicon carbide, gallium arsenide, indium phosphide, gallium nitride, and solid solutions and compounds thereof. The above (4), which is at least one kind selected
A method for producing a metal film-forming inorganic crystal substance according to any one of to (8). (10) The above-mentioned (4) to (9), wherein the metal film layer comprises at least one selected from the group consisting of gold, aluminum, tin or alloys thereof, and nickel, iron, cobalt or alloys thereof. 5. The method for producing a metal film-forming inorganic crystal substance according to any one of 1. (11) The metal film formation according to any one of the above (4) to (10), wherein a catalytic metal ion selected from tin and palladium is adsorbed on the surface irradiated with light before the metal film is formed. Method for producing inorganic crystalline substance.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Diamond, aluminum nitride, cubic boron nitride, silicon nitride, silicon carbide, silicon, germanium, gallium arsenide and the like have extremely high water repellency, and it is usually impossible to perform wet plating. However, the inventors of the present invention have studied the chemical reaction on the surface of covalently bonded crystals such as diamond and aluminum nitride, and as a result, have shown that an amino group can be introduced to these surfaces by a photochemical reaction. Newly discovered, and by introducing an amino group on the surface of the above-mentioned specific inorganic crystal substance to form a metal film, the hydrophilicity is significantly improved, and it was clarified that electroless plating can be performed. The present invention has been completed. Examples of the light source that causes the photochemical reaction include an excimer laser, an excimer lamp light, a low-pressure mercury lamp, a synchrotron radiation device, a synchrotron radiation undulator device, and other soft X-ray light sources, but are not particularly limited thereto. .

As the effect of light irradiation in the present invention, first, the excitation of the surface of the base material is considered. Two types of excitation can be considered, depending on the wavelength band of the irradiation light, excitation of electrons involved in chemical bonding (valence band electrons) and excitation of core electrons of atoms constituting the surface. As an example, the band gap of diamond is about 5.5 eV, and by irradiating light having an energy of about 6 eV, for example, ArF excimer laser, the electrons involved in the chemical bond are excited,
If a molecule having an amino group such as an amine compound or an amide compound is present in the nearest vicinity, an amination reaction of the diamond surface occurs due to the electron transfer reaction. The electrons in the valence band can be excited by irradiating with energy above the band gap of the crystal of the covalent bond compound of the III-V group and the IV group, but it efficiently induces the chemical reaction on the surface. In particular, it is preferable that the light has a wavelength of 260 nm or less. Furthermore, the irradiation of light of a short wavelength makes it possible to excite the core electrons of the atom. The inner shell electrons are not directly involved in the chemical bond, but have the energy peculiar to each atom, and only specific atoms can be excited. That is, it is possible to generate inner-hole holes of atoms, generate positive ions by relaxation process, and selectively excite reaction by cleavage of specific chemical bond. As a molecule that supplies an amino group, it is used in the form of gas or aqueous solution, and ammonia is most suitable. This seems to be related to the simplest molecule that can generate NH ₂ radicals,
It is not particularly limited to this, but the absorption of light causes N
Any compound can be used as long as it generates H ₂ radicals. For example, hydrazine (H ₂ NN
H ₂ ), nitramide (H ₂ NNO ₂ ), sodium amide (H ₂ N · Na) and the like.

In the present invention, the surface of an inorganic crystalline material such as diamond, aluminum nitride, cubic boron nitride, silicon carbide, etc. is aminated, in which case at least 50% or more of the sites capable of binding are aminated. When,
Hydrophilicity required for plating is imparted. For example, in the case of (100) plane of vapor phase synthetic diamond, it is 1 at 2.5 Å angle.
There are sites that can be bonded, and hydrogen atoms are bonded. That is, although hydrogen atoms are present at a density of 1.6 × 10 ¹⁵ pieces / cm ² , at least 50% or more of these hydrogen atoms are replaced by amino groups, and the hydrophilicity is remarkably improved. It was found that the catalysts for electroless plating such as Pd and Pd are effectively and firmly bonded. This is because the amino group itself forms a kind of complex with the metal ion in the solution and chemisorbs the metal ion in the plating solution, but when 50% or more of the sites are replaced with the amino group, chemisorption is performed. It is considered that a plurality of amino groups act as ligands for one Sn ion to form a strong bond.

Next, it is preferable to adsorb catalytic metal ions such as tin and / or palladium ions on the surface.
As a method of adsorption, for example, after immersing in a hydrochloric acid solution of tin chloride (concentration 0.1 to 0.2 mol / liter, 0.2N hydrochloric acid aqueous solution) for 10 minutes at room temperature, it is once washed with water,
Furthermore, an aqueous hydrochloric acid solution of palladium chloride (0.001 to 0.
005 mol / l, 0.2N hydrochloric acid aqueous solution) 10
This is done by soaking for a minute. Although the electroless plating layer is formed by using this catalytic metal as a nucleus, extremely strong adhesion can be realized with the underlying diamond through a chemical bond. The metal film is directly bonded to diamond, aluminum nitride, by an ionic bond and a covalent chemical bond.
It is formed extremely strongly on the cubic boron nitride, silicon nitride, and silicon carbide without any gaps. Electroless plating can be carried out according to a conventional method, for example, in the case of gold plating, in the case of gold plating, after catalytic activation treatment, it is carried out by immersing in an aqueous solution containing cyanoaurate, Similarly, the nickel plating can be performed by activating the catalyst and then immersing it in an aqueous solution containing nickel chloride or nickel sulfate.

In the present invention, if the surface of the inorganic crystalline material is fluorinated before being irradiated with light, the ammonification in the next step proceeds smoothly and a highly water repellent portion and a highly hydrophilic portion are simultaneously formed. There is also an advantage that you can. It is known that the surface of diamond reacts with fluorine or chlorine at low temperature and is covered ("9th Diamond Symposium Abstracts", November 1995, pp.64-6).
5). In particular, fluorination occurs at 0 ° C. or lower, and the fluorinated surface is extremely stable, requiring a temperature of 650 ° C. or higher to substitute with other atoms such as hydrogen. On the other hand, when it reacts with fluorine, it becomes extremely water repellent. In addition, it was newly found that covalent ceramics such as aluminum nitride other than diamond are also fluorinated and have strong water repellency. This fluorinated surface is likewise very stable. Furthermore, on this fluorinated surface, it was found that an amino group can be introduced only into the light-irradiated portion by a photochemical reaction, and by introducing an amino group into the surface of an inorganic substance to form a metal film, It was clarified that the hydrophilicity was significantly improved and electroless plating was possible. As described above, since only the light-irradiated portion is aminated on the fluorinated surface, a highly water-repellent portion and a highly hydrophilic portion can be simultaneously formed, and the line width is 1 μm or less Wiring can also be formed.

[0015]

The present invention will be described in more detail with reference to the following examples. (Example 1) Microwave plasma vapor deposition (CVD)
Thus, vapor-phase synthetic diamond was homoepitaxially grown to a thickness of 3 μm on a mirror-polished diamond single crystal substrate. It was confirmed by observation with a scanning electron microscope and a Nomarski optical microscope that the surface was a mirror surface like the substrate surface. When the wettability of this surface with water was measured, the contact angle of water droplets was 90 °. The diamond sample was placed in a vacuum container having a synthetic quartz window. The distance between the diamond sample surface and the window was 5 mm. After evacuation once, ammonia gas was introduced up to 0.1 mmHg. In this state, the excimer laser (Ar
F) Light was irradiated under the conditions of an energy density of 150 mJ / cm ² , a repetition rate of 5 Hz, and an irradiation pulse number of 1000 pulses. After irradiation, the wettability of this diamond sample with water was measured, and the contact angle of water droplets was 15 °.
Further, the surface of the sample was analyzed by reflection type FT-IR and ESCA, and the presence of amino groups was confirmed, and it was found that almost 100% of the diamond surface was aminated (amination ratio). This diamond sample was electroless plated under the following conditions. That is, after immersing in a hydrochloric acid solution of tin chloride (concentration: 0.15 mol / liter, 0.2N hydrochloric acid aqueous solution) for 10 minutes at room temperature, it is washed once with water, and then palladium chloride hydrochloric acid aqueous solution (0.004 mol / liter) is added. , 0.2 N aqueous hydrochloric acid solution) for 10 minutes. Then, it was immersed in a sulfuric acid aqueous solution (100 ml / l) at 45 ° C. for 2 minutes to remove unnecessary tin ions. In this way, the diamond sample having adsorbed tin and palladium ions was immersed in a gold plating solution having the following composition to form a gold film with a thickness of 5 μm.
It was formed up to m. The composition of the gold plating solution was as follows, and the water temperature during plating was 75 ° C. KAu (CN) 2 0.02 mol / liter KCN 0.2 mol / liter KOH 0.2 mol / liter When the peeling test of this gold film was conducted, it was 100 kg / c.
It was found that they adhered with a strength of m ² or more.

(Example 2) When the wettability of the surface of the aluminum nitride sintered body whose surface was polished to water was measured, the contact angle of water droplets was 95 °. The aluminum nitride sintered body was placed in a container having a synthetic quartz window. The distance between the aluminum nitride sintered body and the window is 1.5 mm
I made it. The container was filled with an aqueous ammonia solution having a concentration of 3% by weight and circulated. In addition, a shortage of ammonia was supplied as needed. In this state, the excimer laser (ArF) is applied to the surface of the aluminum nitride sintered body in the container.
Light, energy density 130 mJ / cm ² , repeated 1
Irradiation was carried out under the conditions of 0 Hz and 1500 irradiation pulses. After irradiation, the wettability of this aluminum nitride sintered body with water was measured, and the contact angle of water droplets was 20 °. The presence of nitrogen atoms and amino groups on the sample surface was confirmed by reflection type FT-IR and ESCA (XPS), and about 95% of the surface of the aluminum nitride sintered body was aminated (amination). Rate) was analyzed. This aluminum nitride sintered body was electroless plated in the same manner as in Example 1. First, tin and palladium ions were adsorbed and then dipped in a gold plating solution to form a gold film with a thickness of 5 μm. When the peeling test of this gold film was conducted,
It was found that the particles adhered at a strength of 100 kg / cm ² or more. Table 1 summarizes the results of experiments conducted on various materials.

[0017]

[Table 1]

(Note) Single diamond; single crystal diamond, fired diamond; diamond sintered body CV diamond; vapor phase synthetic diamond, AlN; aluminum nitride sintered body, SiC; silicon carbide sintered body, Si ₃ N ₄ ; nitriding Silicon sinter, BN; cubic boron nitride sinter, F -... the surface is fluorinated. NH ₃ ap .; 3% aqueous ammonia solution, NH ₃ gas; ammonia gas, Hg; low pressure mercury lamp (250 nm or less), ArF; ArF excimer laser (oscillation wavelength 193 nm), KrF; KrF excimer laser (oscillation wavelength 248 nm), Un ... nm; undulator radiation and oscillation wavelength (nm), SR ... nm;
Synchrotron radiation and oscillation wavelength (nm), T ； mmH
g, phs / mm ² ; photon number, mJ / sc; irradiation energy density (mJ / sc), W; irradiation energy density per unit time (W / cm ² ), P; total irradiation, pulse number, min; irradiation Time, material name and comparative example

(Example 3) IIb type vapor phase synthetic diamond doped with boron was grown to a thickness of 30 μm on a silicon substrate by a microwave plasma vapor deposition method (CVD). After the growth, mechanical polishing was performed for mirror finishing. When the wettability of this surface with water was measured, the contact angle of water droplets was 90 °. The diamond sample was placed in a vacuum container having a synthetic quartz window. The distance between the diamond sample surface and the window was 0.5 mm. After vacuum evacuation, 100mmHg of ammonia gas
Introduced. In this state, the surface of the diamond sample in the container was irradiated with excimer laser (ArF) light under the conditions of an energy density of 150 mJ / cm ² , a repetition rate of 5 Hz, and an irradiation pulse number of 1000 pulses. At this time, the laser beam was transmitted through the mask, and the pattern of the mask was projected on the sample surface. After irradiation, this diamond sample was electroless plated. First, tin and palladium ions are adsorbed and then immersed in a Ni plating solution to form a Ni film with a thickness of 5 μm.
It was formed up to m. The composition of the nickel plating solution is as follows, and the water temperature during plating was 35 ° C. Nickel chloride 0.15 mol / liter Sodium phosphinate 0.12 mol / liter Ammonium chloride 0.65 mol / liter Sodium citrate 0.05 mol / liter The pattern of the formed Ni film is as the reduced projection of the mask pattern, The line width was 0.5 μm. The electrical characteristics of this electrode showed good ohmic characteristics.

Example 4 Hydrazine (H ₂ NNH ₂ )
Was dissolved in pure water to a concentration of 0.1 mol / liter and filled in a container having a synthetic quartz window. A plate-shaped cubic boron nitride sintered body was placed in the liquid at a position 5 mm from the window. The wettability of the surface of this boron nitride sintered body to water before treatment was 85 °. Irradiation with excimer lamp light having a wavelength of about 175 nm was performed for 1 hour. The irradiation light amount is about 5 × 10
^{It was 8} photons / mm ² . After irradiation, it was analyzed that the wettability of the surface of this boron nitride sintered body was improved up to 15 ° and that 80% of the surface was aminated by high resolution XPS. Subsequently, electroless plating of nickel was performed in the same manner as in Example 3. The thickness of the plated layer was 4 μm, and the peel strength was measured to be 100 kg / cm ² .

[0021]

Industrial Applicability According to the present invention, the surface of a portion of an inorganic crystalline substance forming a metal film is directly covered with 0.5 atomic layer (= mono layer) or more and 1 atomic layer or less of nitrogen atoms. A metal film layer (metallized layer) is formed on top of it, so that, especially on inorganic crystalline substances such as diamond, aluminum nitride, gallium arsenide, etc., metals that do not react at all with very weak adhesion strength, or It is possible to form a metal that cannot be treated at a high temperature because it reacts extremely strongly at a low temperature with stable and high adhesion. Wet electroless plating can be performed directly on water-repellent inorganic crystals such as diamond and aluminum nitride at low cost, so that wiring with submicron line width can be produced, or inside of fine and deep perforations with a diameter of several hundred μm or less can be formed. , Enables precise metallization with controlled film thickness, which enables high performance heat sinks used for surface emitting lasers, high power semiconductor lasers, etc.
Furthermore, multi-chip module (M
It is possible to manufacture a heat sink such as CM) that can be cooled with high efficiency while maintaining electrical continuity. As an advantage that does not require treatment at high temperature, after forming the element to some extent,
There is a point that when a metal film is formed on one part afterward, it does not have an adverse effect on other parts, and fine pattern metallization can be formed by PVD using a mask. It is also useful for a process using a laser or for forming a metal film on a finely processed portion such as fine perforations.

Claims (11)

[Claims] 1. The surface of a portion of a periodic table III-V group inorganic crystal substance or a group IV element inorganic crystal substance forming a metal film is 0.5 atomic layer (= mono layer) or more, 1 or more.
A metal film-forming inorganic crystalline material, which is at least covered with nitrogen atoms of an atomic layer or less, and a metal film layer is formed on the nitrogen atom layer. 2. The inorganic crystalline material is selected from the group consisting of diamond, silicon, germanium, cubic boron nitride, aluminum nitride, silicon nitride, silicon carbide, gallium arsenide, indium phosphide, gallium nitride, or solid solutions and compounds thereof. The metal film-forming inorganic crystalline material according to claim 1, which is at least one selected from the group consisting of: 3. The metal film layer comprises at least one selected from the group consisting of gold, silver, tin, copper or alloys thereof, and nickel, iron, cobalt or alloys thereof. The metal film-forming inorganic crystalline substance described in 1. 4. A method for forming a metal film on a group III-V inorganic crystal substance or a group IV element inorganic crystal substance of the periodic table, wherein the molecule contains both nitrogen atom and hydrogen atom,
Or in a mixed atmosphere of molecules each containing one of them or in an aqueous solution, the whole or a part of the surface is irradiated with light in the range of 10 nm or more and 260 nm or less, and then a metal coating layer is formed on the surface by electroless plating. A method for producing a metal film-forming inorganic crystalline material, which comprises forming a film. 5. The metal film-forming inorganic crystal substance according to claim 4, wherein before the light irradiation, the whole surface or a part of the surface of the inorganic crystal substance is fluorinated by contacting with a fluorine gas. Manufacturing method. 6. The method for producing a metal film-forming inorganic crystalline material according to claim 4, wherein the molecule containing a nitrogen element is ammonia. 7. The irradiation light is any one of excimer laser light, excimer lamp light, low pressure mercury lamp light, synchrotron radiation light, and synchrotron radiation undulator light. 5. The method for producing a metal film-forming inorganic crystal substance according to any one of 1. 8. The method for producing a metal film-forming inorganic crystal substance according to claim 4, wherein the excimer laser has an oscillation wavelength of 193 nm. 9. The inorganic crystalline material is selected from the group consisting of diamond, silicon, germanium, cubic boron nitride, aluminum nitride, silicon nitride, silicon carbide, gallium arsenide, indium phosphide, gallium nitride, or solid solutions and compounds thereof. It is at least 1 type which is
5. The method for producing a metal film-forming inorganic crystal substance according to any one of 1. 10. The metal coating layer comprises at least one selected from the group consisting of gold, silver, tin, copper or alloys thereof, and nickel, iron, cobalt or alloys thereof. 10. The method for producing a metal film-forming inorganic crystal substance according to any one of items 10 to 10. 11. The metal film-forming inorganic material according to claim 4, wherein catalytic metal ions selected from tin and palladium are adsorbed on the surface irradiated with light before the metal film is formed. A method for producing a crystalline substance.