JPH0798705B2 - TiN coating method for AIN surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method for modifying the surface of AlN, and more specifically, to a TiN coating on the surface of AlN that is uniform and has excellent bonding properties. Regarding the method.

(Prior Art) Recently, ceramic materials have begun to be used in a wide range of fields such as structural materials and functional materials due to their excellent characteristics. In many cases, parts are made of ceramics alone, but in order to utilize ceramics in more fields, it is necessary to be able to bond with metals. For this reason, the method of metallizing ceramics is extremely effective, and it is desired to establish the optimum method.

Among the ceramics, AlN has attracted attention as a substrate for semiconductor devices because of its high thermal conductivity, and in this case, joining with a conductive material is an essential condition.

By the way, conventionally, the following method has been known as a method for metallizing ceramics.

A method in which a powder containing Mo or w as a main component is applied to the surface of a ceramic base material and heated to 1400 ° C to 1700 ° C in a reducing atmosphere to react with the ceramic base material for metallization.

A method of arranging a foil of Au or Pt on the surface of the ceramic base material and heating the foil while applying pressure to metallize it.

However, the above-mentioned method mainly targets Al ₂ O ₃ as ceramics, and AlN, which has been attracting attention recently,
For, it is not possible to metallize with high adhesion. Further, in the above method, since an expensive precious metal is used, the economy is poor, and a high pressure is required for the purpose of enhancing the adhesiveness, which is not preferable for a part which does not like to be deformed.

On the other hand, not only metal is a material exhibiting conductivity, but TiN is a conductive ceramic that has recently attracted attention among ceramics. If TiN can be coated on the surface of AlN,
It is possible to obtain more effects than metalized. This is because TiN is the same ceramic as AlN, so it is not necessary to consider the occurrence of thermal stress, which is a problem during metallization.

Generally, a chemical vapor deposition method or a physical vapor deposition method is used as a method for coating TiN. However,
These methods cannot be expected to have sufficient bonding simply because they are mechanically attached to the surface of the base material. It is structurally and mechanically unsatisfactory.

(Problems to be Solved by the Invention) As described above, if the surface of AlN can be coated with TiN, the range of application of AlN can be expected to increase significantly, but a coating that combines AlN and TiN sufficiently In order to obtain this, there is a problem that a chemical reaction must occur at the interface between the two.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the conventional problems and provide a TiN coating method for an AlN surface uniformly and by a simple process without causing thermal stress.

[Structure of Invention]

(Means and Actions for Solving Problems) The inventors of the present invention performed characterization of an interface related to a base of a brazing filler metal containing an active metal, which is effective in joining AlN and a metal, It was found that TiN was formed at the interface when Ti was used as the metal.
Therefore, as a result of various attempts to form TiN on AlN using Ti, the present invention has been accomplished.

That is, the present invention, the TiN coating on the AlN surface, which is characterized by exposing the AlN surface to an active state by exposing the AlN to a high-temperature vacuum, and making the AlN periphery a vapor atmosphere of Ti or a metal containing Ti. Is the way. Specifically, AlN
And Ti or a base metal containing Ti are brought into non-contact state or in a state where no force is applied even if they come into contact with each other, and they are placed in a container such as an alumina crucible and heated in a vacuum furnace. Obtained by As a result, Ti vapor flying to the AlN surface reacts with AlN, and Ti on the AlN surface
Form N. And by the reaction with this Ti vapor, AlN
A uniform TiN coating is formed on the surface.

Ti used in the present invention may be plate-like or powder-like, and is a base metal containing Ti used in the same manner
Ti-6An-4V etc. can be mentioned. These Ti or alloys containing Ti are placed in a closed container together with AlN, but they may be placed apart from each other within a range where Ti vapor reaches the AlN surface, or in a state where no further pressure is applied, It may be installed in contact. At this time, for example, by contacting plate-like Ti and plate-like AlN and pressurizing both with a pressure of 0.1 kg / cm ³ or more, both interfaces become a sealed state, and Ti necessary for the reaction
No steam is generated and good results cannot be obtained. The vacuum in the present invention is preferably a vacuum degree of 5 × 10 ⁻⁵ Torr or higher, and a low vacuum degree of less than that inhibits evaporation of Ti. Further, the heating conditions in the present invention are, for example, in the range of 1100 ° C to 1400 ° C for 0.1 hour to 15 hours, whereby a preferable coating layer can be obtained. As a result, a coating of TiN having a thickness of about 0.5 μm to 10 μm is formed on AlN.

(Example) Example 1 An AlN plate having a diameter of 100 mm and a thickness of 2 mm was prepared and placed in an alumina crucible having a JIS Class 3 Ti plate placed on the bottom. Furthermore, the crucible is also covered with an alumina lid,
These were placed in a vacuum furnace. Then, after evacuating to a vacuum of 1 × 10 ^-6 Torr or more, the temperature was raised to 1250 ° C. and kept for 3 hours. After cooling, it was taken out of the furnace and a uniform and thin coating layer was formed. When the coated AlN was cut and its cross section was observed, the thickness of the metallized layer was about 3 μm. Also, the surface X
Line diffraction revealed that the metallized layer was TiN.
This means that the coating layer is not simply vapor deposited, but chemically reacts with AlN to bond with it.

Example 2 A plate of AlN having a diameter of 100 mm and a thickness of 2 mm was prepared, and this was used as 98% T
The powder was placed in a crucible made of alumina so as not to be in contact with the powder. Further, the crucible was also covered with an alumina lid, and these were placed in a vacuum furnace. Then, after evacuating to a vacuum of 1 × 10 ^-6 Torr or more, the temperature was raised to 1200 ° C. and kept for 3 hours. After cooling, it was taken out of the furnace and a uniform and thin coating layer was formed. When the coated AlN was cut and its cross section was observed, the thickness of the metallized layer was about 0.5 μm. Further, it was found from the X-ray diffraction of the surface that the metallized layer was TiN. This means that the coating layer is not simply vapor deposited, but chemically reacts with AlN to bond with it.

〔The invention's effect〕

Since TiN has conductivity as described above, it can be used as it is as an electronic element, but it can also be used by electroplating a metal through TiN. Also, TiN
Since it has a good brazing property, it can be joined to other metals. Furthermore, TiN can be used as a decorative product because its color is gold.

Claims (1)

[Claims] 1. A TiN coating for an AlN surface, which comprises exposing the AlN surface to an active state by exposing the AlN surface to a vapor atmosphere of Ti or a metal vapor containing Ti, and exposing the AlN surface to an active state. Method.