JPH09311208A - Aln reflection mirror - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an AlN reflection mirror having high heat resistance and thermal conductivity, excellent adhesion property between the base and a metal layer and good workability of the reflection face and improved productivity. SOLUTION: This AlN reflection mirror consists of an aluminum nitride sintered body base 11, an Al2 N3 layer 12 formed by heating and oxidizing the base body 11, and an SiO2 layer 13 formed on the Al2 O3 layer 12, and a noble metal thick film 14 formed on the SiO2 layer 13. The aluminum nitride sintered body contains preferably 0.1 to 10wt.% of one or two kinds of metal oxides selected from Y2 O3 and CaO. The Al2 O3 layer 12 is preferably formed to 0.2 to 20μm thickness and the SiO2 layer 13 is preferably formed to 0.01 to 10μm thickness. The surface roughness as the center line average roughness of the noble metal thick film 14 is preferably controlled to <0.2μm, and the noble metal thick film 14 preferably contains one or more kinds of metals selected from Au, Ag, Pd and Pt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for reflecting infrared rays emitted from an infrared heater such as a halogen heater, and has high thermal conductivity and heat resistance which can be used for a condenser for semiconductor manufacturing, a laser mirror and the like. The present invention relates to the AlN reflector.

[0002]

2. Description of the Related Art Conventionally, as this type of reflecting mirror, a base 9 having a concave surface 9a whose upper surface is curved is formed by extrusion of Al as shown in FIGS. 4 and 5, and the concave surface 9a of the base 9 is formed. A reflecting mirror 1 having Al as a base on which a plated layer 4 is formed is known. In this reflecting mirror 1, after buffing the concave surface 9a of the base 9, a Ni plating layer 4a is formed on the concave surface 9a, and an Au plating layer 4b is formed on the surface of the Ni plating layer 4a. A halogen heater 6 is installed in the vicinity of the focal point of the reflecting surface 1a which is the surface of the plating layer 4. Further, although not shown, there is known a reflecting mirror based on a Cu alloy formed in the same manner as the above-mentioned conventional reflecting mirror, except that a Cu alloy is used instead of Al for the substrate of the conventional reflecting mirror. .

However, in the conventional Al-based reflector, the temperature of the substrate rises during use of the reflector, and
There was a problem that the grains grew and the surface of the reflecting mirror was roughened and the reflectance was lowered. Further, in the above-mentioned conventional reflecting mirror using a Cu alloy as a base, when the reflecting mirror is used in the atmosphere, the temperature of the base increases and Zn, which is an alloy component of the base, is used.
And the like are diffused into the plating layer, and the surface roughness and discoloration of the reflecting mirror are caused along with this, resulting in a problem that the reflectance is reduced. Further, in the above-mentioned conventional reflecting mirror using a Cu alloy as a base, there is a problem that the Cu alloy as a base is corroded when the reflecting mirror is used in water, and durability is reduced. In order to eliminate these points, Al having a curved surface by press molding or the like
Attempts have been made for a reflecting mirror in which a ceramic substrate made of ₂ O ₃ or AlN is prepared and a metal film is formed on the curved surface by the thick film method.

[0004]

However, the reflector of the substrate made of Al ₂ O ₃ has a problem that the thermal conductivity is low. Further, although the reflecting mirror of the substrate made of AlN has higher heat resistance and thermal conductivity than Al ₂ O ₃ , the glass component in the thick film and AlN react with each other during firing of the thick film to generate NO _x gas. There are problems that bubbles are generated at the interface between the thick film and the substrate, the thick film swells, the curved surface becomes rough, and the adhesion of the thick film decreases. An object of the present invention is to provide an AlN reflecting mirror that has high heat resistance and thermal conductivity and is excellent in the adhesion between the substrate and the metal layer. Another object of the present invention is to provide an AlN reflecting mirror having a good workability of the reflecting surface and improving the productivity.

[0005]

The invention according to claim 1 is
As shown in FIG. 1, a base body 11 made of an aluminum nitride sintered body, an Al ₂ O ₃ layer 12 formed on the surface of the base body 11 by thermally oxidizing the base body 11, and provided on the Al ₂ O ₃ layer 12. This is an AlN reflecting mirror including the formed SiO ₂ layer 13 and the noble metal thick film 14 provided on the SiO ₂ layer 13. In the reflecting mirror 10, since the Al ₂ O ₃ layer 12 and the SiO ₂ layer 13 are formed on the AlN substrate 11, it is possible to prevent the reaction between glass and AlN in a wide composition range. That is, Al
AlN substrate 11 on which ₂ O ₃ layer 12 and SiO ₂ layer 13 are formed
When the thick film paste is printed and fired on the top, the reaction between the glass component contained in the thick film and the AlN substrate 11 can be prevented, and the noble metal thick film 14 can be firmly adhered to the substrate 11. it can.

The invention according to claim 2 is the invention according to claim 1, wherein the aluminum nitride sintered body is Y ₂ O ₃ and Ca.
The AlN reflecting mirror contains 0.1 to 10% by weight of one or two kinds of metal oxides selected from the group consisting of O. Y ₂
By containing O ₃ and CaO, the sinterability of aluminum nitride is improved. In this case, the content rate is 0.1% by weight
If it is less than 10% by weight, sufficient sinterability cannot be obtained, and if it exceeds 10% by weight, the thermal conductivity of the substrate itself is lowered. The invention according to claim 3 is the invention according to claim 1 or 2,
The Al ₂ O ₃ layer 12 has a thickness of 0.2 to 20 μm, and SiO ₂
The layer 13 is an AlN reflecting mirror having a thickness of 0.01 to 10 μm. Al ₂ O ₃ layer 12 is less than 0.2 μm or SiO ₂ layer 1
If 3 is less than 0.01 μm, the adhesion of the firing layer of the noble metal paste described below is insufficient, and the Al ₂ O ₃ layer 12 has a thickness of 2
If it exceeds 0 μm or if the SiO ₂ layer 13 exceeds 10 μm, the thermal conductivity of the substrate itself decreases.

The invention according to claim 4 is the invention according to claims 1 to 3
It is an invention according to any one, and is an AlN reflecting mirror in which the surface roughness of the noble metal thick film 14 is 0.2 μm or less in terms of center line average roughness. If the surface roughness of the noble metal thick film 14 exceeds 0.2 μm in the center line average roughness, diffuse reflection of infrared rays is likely to occur and sufficient reflectance characteristics cannot be obtained. The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the noble metal thick film 14 comprises one or more metals selected from the group consisting of Au, Ag, Pd and Pt. Including AlN
It is a reflector. If the noble metal thick film 14 is Au, Ag, Pd and Pt, it becomes possible to sinter in the air and at a relatively low temperature.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. As shown in FIGS. 1 to 3, the aluminum nitride sintered body as the base body 11 of the present invention is not limited to a sintered body made of only aluminum nitride, but contains aluminum nitride as a main component and various additives such as CaO. ，
A sintered body containing Y ₂ O ₃ or the like may be used. When this additive is used, it is preferable to use Y ₂ O ₃ or CaO as the ceramic sintering aid powder and to contain the metal oxide in an amount of 0.1 to 10% by weight. The base 11 may be a plate-shaped substrate as shown in FIG. 1 or a bulk-shaped substrate as shown in FIG. A halogen heater 18 is installed near the focal points of the quadratic curves of the reflecting mirrors 10 and 20. Further, the reflecting surface may be a concave surface as shown in FIGS. 1 and 3, or may be a flat surface (not shown). In the bulk state shown in FIG. 3, after the powder is filled in a mold of a predetermined shape, pressure is applied for molding, that is, a so-called press molding method, or the powder is suspended in a dispersion medium (medium liquid). It is preferably formed by a so-called slip casting method in which it is deflocculated into a suitable state to obtain a sludge having a fluidity, which is poured into a mold having a desired shape to be molded.

The Al ₂ O ₃ layer 12 provided on the substrate is an atmosphere in which the aluminum nitride sintered body has an oxygen partial pressure of 1 × 10 ⁻² atm or more and a water vapor partial pressure of 1 × 10 ⁻³ atm or less. In, it is made by heat treatment at 1100 to 1500 ° C. for about 3 to 0.5 hours. The higher the temperature, the shorter the processing time may be. By this heat treatment, the surface of the aluminum nitride sintered body is oxidized and the Al ₂ O ₃ layer 12 is formed. In this case, the thickness of the Al ₂ O ₃ layer 12 is 0.2 to 2
It is preferably 0 μm.

Next, the SiO ₂ layer 1 provided on this reflecting mirror
3 is formed by the sol-gel method. That is, the SiO ₂ layer 13 is formed on the Al ₂ O ₃ layer 12 formed by the thermal oxidation as described above.
It is prepared by applying an i-alkoxide solution, subjecting it to hydrolysis and a polymerization reaction, and performing heat treatment at 600 to 1000 ° C. for about 0.5 to 3 hours. In this case, the SiO ₂ layer 13 preferably has a thickness of 0.01 to 10 μm. As shown in the enlarged view of FIG. 1, in this reflecting mirror 10, Si provided on a substrate 11 made of a sintered body with an Al ₂ O ₃ layer 12 interposed therebetween.
A noble metal thick film 14 is further formed on the O ₂ layer 13.
The surface roughness of the noble metal thick film 14 is formed to have a center line average roughness of 0.2 μm or less by mechanical polishing. The noble metal thick film 14 contains one or more metals selected from the group consisting of Au, Ag, Pd and Pt.

The noble metal thick film 14 is formed by a thick film method. That is, the noble metal film 14 has a grain size of 200 mesh or more.
A paste in which an organic binder such as ethyl cellulose and an organic solvent such as terpineol are added to one or more kinds of metal powders and glass powders selected from the group consisting of u, Ag, Pd and Pt by a screen printing method, etc. ₂
It is coated on the layer and kept at 70 to 200 ° C. for 5 to 30 minutes in the atmosphere to be dried. As the glass powder, one that softens or melts at a temperature equal to or lower than the melting temperature of the metal powder and adheres to the metal powder or the substrate body is used. For example, SiO ₂ −
It is preferable to use oxide glass such as B ₂ O ₃ —Bi ₂ O ₃ system or SiO ₂ —B ₂ O ₃ —PbO system. The amount ratio of metal powder and glass powder in the paste was 60% by weight: 4
It is preferably in the range of 0% by weight to 95% by weight: 5% by weight. The range is limited to the noble metal thick film 14 obtained after firing when the metal powder is less than 60% by weight.
This is because the infrared reflectance becomes low, and if the metal powder exceeds 95% by weight, the strength of the thick film decreases.

After the above paste is dried, 5 in a predetermined atmosphere
By holding at 00 to 1000 ° C for 5 to 30 minutes,
The above paste is fired to form a film with a thickness of 5 on the SiO ₂ layer 13.
A noble metal thick film 14 of about 50 μm is formed. The noble metal thick film 14 on the SiO ₂ layer 13 is polished by a general metal polishing method. Abrasive particles having a particle size of 40 to 1500 mesh are fixed to a polishing cloth with a predetermined adhesive, and the polishing cloth is pressed against the surface of the noble metal thick film on the substrate body with a predetermined pressure while pouring a water-soluble grinding liquid. , 500-2000m /
The noble metal thick film surface is polished by moving at a speed of a minute. As abrasive grains, Al ₂ O ₃ , SiC, garnet,
Fine particles such as diamond are used, an adhesive such as glue or resin is used as the adhesive, and a sheet formed of kraft paper or a nonwoven fabric of nylon fiber is used as the polishing cloth. The surface roughness of the noble metal thick film is preferably 0.2 μm or less in terms of center line average roughness by this polishing.

[0013]

Next, embodiments of the present invention will be described. <Examples 1 to 9> The reflecting mirror 10 shown in FIG. 1 was manufactured by the following method. First, nine aluminum nitride sintered substrates each having a concave surface were prepared, and the heat treatment time was changed at 1300 ° C. in the atmosphere, and the surface of each sintered substrate was changed to 0.2 μm.
_Three Al ₂ O ₃ layers 12 each having a thickness of 4.1 μm and a thickness of 19.4 μm were formed. Next, the aluminum nitride sintered substrate 11 on which the Al ₂ O ₃ layer 12 is formed is dip-coated with a liquid obtained by mixing 348 g of ethyl silicate, 92 g of isopropyl alcohol, 500 g of ethanol, and 60 g of a 0.3% HCl aqueous solution, and then air. The SiO ₂ layer 13 was formed by firing at 900 ° C. for 1 hour in the atmosphere. Table 1 shows the thickness relationship between the Al ₂ O ₃ layer 12 and the SiO ₂ layer 13.

An Au thick film 14, which is a noble metal thick film, was formed on the SiO ₂ layer 13. The formation of the Au thick film 14 will be described below. First, 80 g of Au powder having a particle size of 325 mesh or more and ₂ g of SiO ₂ —B ₂ O ₃ —PbO glass powder were used.
A paste was prepared by mixing and kneading 0 g, ethyl cellulose 1.5 g, and terpineol 20 g in a weight ratio.
The paste is applied onto the SiO ₂ layer by a screen printing method, kept at 150 ° C. for 10 minutes in the air atmosphere to dry, and then kept at 850 ° C. for 10 minutes in the air atmosphere to burn the paste, An Au thick film 14 having a film thickness of 20 μm was formed on the Al ₂ O ₃ substrate 11. A after firing
To the u thick film 14, a polishing cloth made of a nonwoven fabric sheet of nylon fiber in which Al ₂ O ₃ fine particles having a grain size of 600 mesh are adhered with an adhesive is brought into close contact, and this polishing cloth is used as the Al ₂ O ₃ substrate 1
1 was moved at a speed of 600 m / min to polish the surface of the Au thick film 14. The polishing amount was 4 μm in terms of the amount of reduction in the thickness of the Au thick film 14. The respective reflecting mirrors 10 manufactured in this manner are referred to as Examples 1 to 9.

Comparative Example 1 An aluminum thin film having the same concave surface as in Example 1 was not heat-treated, but an Au thin film was formed directly on the surface of the substrate by the same method as in Example 1, and Example 1 was used. Polishing was performed in the same manner as in. The reflecting mirror manufactured in this manner was used as Comparative Example 1. <Comparative Examples 2 to 4> The aluminum nitride sintered substrate having the same concave surface as in Example 1 was heat-treated in the same manner as in Example 1 to give A.
After forming the l ₂ O ₃ layer without providing the SiO ₂ layer, the Al ₂
An Au thin film was formed on the surface of the O ₃ layer by the same method as in Example 1, and polishing finishing was performed in the same manner as in Example 1. The reflecting mirrors manufactured in this manner are Comparative Examples 2 to 4. <Comparative Examples 5 to 7> The aluminum nitride sintered substrate having the same concave surface as in Example 1 was subjected to the same S as in Example 1 without heat treatment.
An iO ₂ layer was formed. An Au thin film was formed on the surface of the SiO ₂ layer by the same method as in Example 1, and polishing finishing was performed in the same manner as in Example 1. The reflecting mirrors manufactured in this manner are Comparative Examples 5 to 7.

<Comparative Test and Evaluation> With respect to the reflecting mirrors of Examples 1 to 9 and Comparative Examples 1 to 7, the infrared reflectance and the adhesion of the Au thick film to the substrate were comparatively tested. Table 1 shows the results. The reflectance is obtained by measuring the total reflectance of infrared rays when the Au thick film on the substrate is irradiated with infrared rays having a wavelength of 2.5 μm.
The adhesion of the thin film is 50
The Au thin film was subjected to a peeling test at 0 ° C. for 100 hours before and after the aging treatment, and the peeled portion or the broken portion was judged.

[0017]

[Table 1]

As is clear from Table 1, in Comparative Example 1, the infrared reflectance was as low as about 80%, and the adhesion of the Au thick film was also low. Moreover, Comparative Examples 2 to 4 and Comparative Example 5
7 to 7, the reflectance was improved as compared with Comparative Example 1, but Au
The adhesion of the thick film was still low. On the other hand, in Examples 1 to 9, a high reflectance of 90% or more was maintained, and the adhesion of the Au thick film also showed a high value as compared with Comparative Examples 1 to 7. In Comparative Example 1 in which the Au thin film was directly formed on the aluminum nitride sintered substrate,
While it was possible to visually confirm a large number of bubbles on the surface of the u thin film, in the example, there was no change in the Au thin film,
It was found to show a high reflectance.

[0019]

As described above, according to the present invention, the reflection on the SiO ₂ layer provided through the Al ₂ O ₃ layer formed by thermal oxidation on the substrate made of the aluminum nitride sintered body is reflected. Since the noble metal thick film serving as the surface is provided, the noble metal thick film having high adhesion to the sintered body can be formed. As a result, it is possible to obtain an AlN reflecting mirror having high heat resistance and thermal conductivity and having excellent adhesion between the base and the metal layer. In addition, SiO
_{Since the} noble metal thick film serving as the reflecting surface is provided on the _two layers, even if the surface roughness of the substrate is large, the noble metal thick film itself flattens it and the surface of the noble metal thick film becomes a mirror surface without distortion. Even when the reflectance is further improved, the polishing does not require polishing of the aluminum nitride sintered body which is the base, and the surface of the noble metal thick film can be polished to improve the reflectance.

[Brief description of drawings]

FIG. 1 is a sectional view of a reflecting mirror of the present invention.

FIG. 2 is a perspective view thereof.

FIG. 3 is a sectional view of another reflecting mirror of the present invention.

FIG. 4 is a cross-sectional view taken along the line BB of FIG. 5 showing a reflecting mirror of a conventional example.

FIG. 5 is a perspective view of a main part including a reflecting mirror of the conventional example.

[Explanation of symbols]

10, 20 Reflector 11 Base 12 Al ₂ O ₃ layer 13 SiO ₂ layer 14 Noble metal thick film

Claims (5)

[Claims] 1. A base (1) made of an aluminum nitride sintered body.
1), an Al ₂ O ₃ layer (12) formed on the surface of the substrate (11) by thermally oxidizing the substrate (11), and a SiO ₂ layer provided on the Al ₂ O ₃ layer (12). An AlN reflecting mirror comprising a layer (13) and a noble metal thick film (14) provided on the SiO ₂ layer (13). 2. The aluminum nitride sintered body is Y ₂ O ₃ and C.
The AlN reflecting mirror according to claim 1, which contains 0.1 to 10% by weight of one or two kinds of metal oxides selected from the group consisting of aO. 3. The AlN reflecting mirror according to claim 1, wherein the Al ₂ O ₃ layer (12) has a thickness of 0.2 to 20 μm and the SiO ₂ layer (13) has a thickness of 0.01 to 10 μm. 4. The AlN reflecting mirror according to claim 1, wherein the noble metal thick film (14) has a surface roughness of 0.2 μm or less in terms of center line average roughness. 5. The noble metal film (14) comprises Au, Ag, Pd and P.
The AlN reflecting mirror according to any one of claims 1 to 4, which contains one or more metals selected from the group consisting of t.