JPH01249681A - Aluminum nitride sintered compact having metallized surface and its production - Google Patents

Abstract

PURPOSE:To improve the adhesive strength and airtightness of a metallized layer without deteriorating the subject sintered compact by incorporating metallic Cu, Ni, Mo, and W, their compds., the compds. of Ca, Sr and Ba, a solid soln., and an Al compd. into the metallized surface of an AlN sintered compact. CONSTITUTION:One or more kinds among Cu, Ni, Mo, W, and their alloy and compd., >=1 kind among the compds. of Ca, Sr and Ba, and the mixture and solid soln., and an org. binder are mixed and kneaded to obtain metallic paste, and the paste is applied on the surface of an AlN sintered compact. The material is calcined in an inert or reducing atmosphere to form a metallized layer on the sintered compact surface. When the Telefunken method is applied in the metallization of an AlN sintered compact in this way, an additive assistant such as CaO-Al2O3 and CaO-AlON is added into the metallic paste, and the paste is calcined in an inert atmosphere. Consequently, a metallized layer having excellent adhesive strength and airtightness can be obtained without deteriorating the high heat conductivity of AlN.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an aluminum nitride sintered body having a surface metallized with molybdenum and/or tungsten, and a method for manufacturing the same.

[Conventional technology]

Aluminum nitride (ΔρN) sintered body has high thermal conductivity,
Due to its excellent mechanical strength, it is attracting attention in many fields including insulating substrates for ICs. However, aluminum nitride sintered bodies have poor wettability with metals, and even if a metal layer is laminated on the required surface for use as substrates for various ICs including power transistors and transistors, the adhesion strength is insufficient. The drawback was that it could not be used. Therefore, Af
Although attempts have been made to metallize the surface of fN sintered bodies, no satisfactory method has yet been proposed.

On the other hand, as metallization technologies for aluminum oxide (Ag2O3) sintered bodies, tanksten, tanksten-manganese,
The Telefunken method is known, in which molybdenum or molybdenum-manganese paste 1- is applied to the surface of a sintered body and fired at a temperature of 1300° C. to 1700° C. in humidified hydrogen or humidified forming gas.

The feature of this method is that it is fired in a humidified atmosphere at a temperature that softens the glass phase in the Δρ203 sintered body.
By this firing, the surfaces of W, Mo and Mn are oxidized and W
, W'-MnMo or Mo-Mn paste, these oxides dissolve into the glass phase of the sintered body and improve the fluidity of the glass, and the glass phase becomes porous. W, W-Mn) 40 or un -Mn metallization layer. Furthermore, oxides produced by calcination, especially M
nO reacts with ΔLO3 and 5102 in the sintered body to form Mn.
Form O.Ag2O3 and Mn0-3i02. Similarly, part of W or Mo is oxidized, and tungsten oxide or molybdenum oxide and alumina react strongly.

In this way, W, ilo or W-Mn, Mo-
The Mn metallized layer is firmly adhered to the Haku203 sintered body through mechanical and chemical bonding, and the adhesive strength is approximately 4 to 7K.
It will be about g/mm2.

Even if an attempt is made to metalize an AffN sintered body using the Telefunken method, the surface of the AβN sintered body will be corroded or altered by water vapor and become brittle Al2 because it is fired in a humid atmosphere.
203 layers are formed, ■Af in the Al2N sintered body.
f20. There is no glass phase that softens at a low temperature of about 1000 to 1500°C like a sintered body, ■AQN and W
Due to poor reactivity with Mo, Mn and their oxides, the obtained WMo or W-MnLto-
The Mn metallized layer had low adhesive strength and extremely poor airtightness.

When using a ΔffN sintered body as an IC substrate, etc., if the adhesive strength of the metallized layer is low, it will easily peel off during the thermal cycle of the manufacturing process, and the metallized layer will have poor airtightness and poor old strength (J However, there are problems such as not being able to obtain satisfactory sealing performance.

In order to apply the Telefunken method to the metallization of AρN sintered bodies, the present inventors proposed that CaO-AR20, CaO-AffO
When we tried a method of adding additives such as N or Ca0-Alx and firing in an inert atmosphere, we were able to solve the problems of adhesive strength and airtightness.

With the composition of the additive auxiliary agent described above, it was observed that a melt was generated at temperatures below 1400° C., sufficiently wet the surface of the 12N sintered body, and firmly adhered to the surface. However, in order to sufficiently sinter W or Mo in order to obtain airtightness of the metallized layer, it is necessary to sinter at a temperature of 1700°C or higher. Aff
Interdiffusion and reaction occurred between the 203 series, Y2O3-AR20, and the above-mentioned additive auxiliaries, and a degraded layer was observed inside the AffN surface approximately 100 μm away from where the metallized layer was formed. . This altered layer significantly impaired the high thermal conductivity, which is a characteristic of the AρN sintered body, and the original effect was not observed.

For example, when the above metallized layer was formed on the surface of an AρN sintered body having a thermal conductivity of 220 W/mK by firing, the thermal conductivity of the Al2N sintered body decreased to 140 W/mK. And when the altered surface is removed, the original 220W/mK
The value of was obtained.

In this way, although the problems of adhesive strength and airtightness were solved, a new problem occurred in that a degraded layer was formed on the surface of the Aj2N sintered body and the thermal conductivity was greatly reduced.

[Problem that the invention seeks to solve]

The object of the present invention is to provide an aluminum nitride sintered body having not only high strength and high airtightness but also a Mo or W metallized surface that does not impair the high thermal conductivity of Alx, and a method for manufacturing the same.

[Failure to solve the problem]

The auxiliary agent contained in the Mo or/and W metallization layer and Aρ
Reaction with substances that constitute the grain boundary layer in the N sintered body.

We will clarify the method and structure for suppressing diffusion, sufficiently sintering MO or W metal, and firmly adhering it to an AffN substrate.

01. Promote the sintering of W or MO at 400°C to 1600°C - The melt generated in the metallized layer sufficiently wets the AρN surface and the above metal surface, and firmly adheres it. It will be revealed that the liquid does not diffuse much into the AρN sintered body and does not react so much that a reaction layer that causes a decrease in thermal conductivity is not formed on the AβN surface layer.

[Effect]

Calcium, strontium and barium fluoride or oxide powders, when mixed with aluminum oxide, aluminum oxynitride or aluminum nitride powders, easily react with nitrogen.

In particular, it was observed that a melt was formed by heating nitrogen-hydrogen to about 1,400°C to 1,500°C. Moreover, it was found that the surface of the AρN sintered body was sufficiently wetted and firmly adhered to the surface. Therefore, a Mo or W paste was prepared by kneading these mixtures with Mo or W powder and an organic binder. AR by screen printing these pastes
Print a predetermined pattern on the surface of the N substrate], 500.1
It was fired at 700° C. in 30 ml of nitrogen. In the former sample, the sinterability of MO and W metals was insufficient and airtightness could not be obtained, but no altered layer was observed in the AρN substrate.

Furthermore, it was observed that the melt produced by the mixture of auxiliary agents mixed into the paste described in item 1 had sufficient numbers of Mo or W grains on the surface of the ρN surface and were firmly adhered to the paste. However, in the latter sample, the Mo and W metal layers were firmly adhered to AρN, and although airtightness was obtained, AρN
It was observed that an altered layer was formed on the surface of the sintered body. The sinterability of the metal layer was determined by the firing conditions of the former sample.
After making earnest efforts regarding 2, I found that Mo or W in 1.
When a small amount of Ni and/or Cu powder was added to the paste, it was observed that the sinterability of these metal layers was significantly promoted.

It is thought that this Ni or Cu powder reacts with the surface of the Mo or W grains to improve sinterability.

This sintering promotion effect is due to the fact that in addition to Ni and Cu metals, Cu-N
i alloy, Cu-Mo, Cu-W, Ni-Mo,
Ni-Cu, Cu-Ni-Mo, Cu-Ni
-W alloy was also observed. Note that the oxides of Cu and Ni also decompose during firing to become Ni and Cu metals, so they exhibit exactly the same effects.

It should be noted that when the firing was carried out in a N21 (mixed gas) flow, the sinterability of the metal layer was further improved.

Therefore, the present invention combines powders of one or more powders selected from calcium, strontium, and barium compounds and powders of aluminum compounds, as well as one or more powders selected from copper, nickel alloys, and oxides of tungsten or nickel. / and relates to a structure or production in which a metal paste prepared by adding and kneading molybdenum metal together with an organic binder is applied to the surface of an aluminum nitride sintered body and fired in nitrogen or a nitrogen-hydrogen atmosphere.

The melt of the mixing aid contained in the paste and N1 or Cu
Due to the gold metal base alloy effect, a metalized surface of W or/and Mo with high strength and high airtightness can be provided at a relatively low temperature with extremely little decrease in thermal conductivity of AffN. The structure of the constructed sample consists of a metal surface of Mo and/or W sintered in the metallized layer, a mechanical part thereof, and an auxiliary agent or its reactant added to the paste between the ARN and those metal surfaces. Intervening. The N1 or Cu metal or alloy is present in the metal layer, particularly at the grain boundaries of the W or/and Mo metal surface, together with the above-mentioned auxiliary agent or its reactant. Note that the airtightness can be further improved by plating with Ni or the like on the metallized layer.

Metal salts other than calcium oxide, strondium, and barium, such as nitrates, carbonates, and sulfates, decompose into oxides during firing, so they exhibit exactly the same effects.

The powders of calcium, strontium, and barium compounds and the powders of aluminium compounds described in item 1 exhibit the above-mentioned effects even if the content in the W, Mo paste is small.

The amount of addition of powder of strontium and barium compounds is 1 to 35 parts by weight per 100 parts of molybdenum or/and tungsten, and the amount of powder of the latter aluminum compound added is 1 to 100 parts by weight of molybdenum and/or tungsten.
It is particularly preferable that the amount is 1 to 35 parts by weight based on 00 parts by weight. If any component is less than 1 part by weight, the bonding strength will decrease, and if it exceeds 35 parts by weight, the thermal conductivity of the metallized surface will decrease.

Copper, nickel, their alloys, and their compounds are effective in promoting sintering of metallized surfaces. The amount added is preferably 0,001 to 10 parts per 100 parts by weight of tungsten or molybdenum. If it exceeds 10 parts by weight, it is not preferable because it will form an alloy with tungsten, molybdenum, etc.

Adding more of these auxiliaries can cause other problems. In other words, the amount of melt generated during firing increases, and a portion of it is precipitated on the W or/and Mo surface. Even if plating is applied to the surface, the adhesion of the plating becomes a problem.

In particular, N2−1− at 1400–1500 °C by W paste consisting of W, CaO, Ag2O3+ N+ powder.
Particularly good are those fired in a 12 atmosphere. Also, A
The ρN sintered body may have any grain boundary composition of 2Ml weave, but if we mention the metallization method, which is characterized by high thermal conductivity, the thickness of the grain boundary layer is small and the ARN sintered body is Particularly preferred are compositions that occupy a small amount and have a high melting point in the composition constituting the grain boundary layer. In short, it is necessary to consider the reactivity and diffusion amount of the auxiliary agent contained in the paste during firing, and a preferable ARN sintered body has a thermal conductivity of 180 W/mK or more and a rare earth element content of 0.01 to
1.0 weight percent.

Containing 0.001 to 0.5 percent by weight of oxygen, Af
The average crystal grain size of fN is 5 μm or more.

The thickness of the metallized layer is 5 to 30 μm, which is very thin and has good thermal conductivity, so the decrease in thermal conductivity of ARN with a metallized surface can hardly be tolerated by this layer.

Example 1 A tanksten molybdenum base was prepared by kneading powders of the components shown in the table below, tungsten or molybdenum powder, and a binder. The surface of the 12N sintered body is printed with a predetermined pattern,
It was fired in an atmosphere of N2 or N2-1 (. The tensile strength was measured after 2-3 μm Ni plating was applied to the metallized surface formed in the shape of a 2 mm square pad.
Copal wire of mmφ was silver soldered at 830 t in the direction perpendicular to the metallized surface. Then, the vertical tensile strength was measured. In addition, the thermal conductivity measurement method of ARN with metallized surface is as follows.
Nl on the metallized surface.

After applying Au plating, the field effect transistor is
It is mounted on the U plating surface with Au solder. And A.V.
The thermal conductivity of the AffN sintered body was calculated from the transient thermal resistance value generated by the 1-run sister using the AV method.

The thermal conductivity of ARN before firing is 220W/mK.

In addition, with the components of the above comparative example, N2°N at 1600°C or less
2-I tried firing in N2 and their humidified atmospheres, but
The tensile strength is as low as 2 Kg/mm2 or less, which does not reach a practical level. And those fired in a humidified atmosphere are Af
Alteration was observed on the fN surface.

When the sample of the example was tested for airtightness (sample treated with Ni plating) using the He IJ method, the results were as follows.
It was found that the leak rate was on the order of IQ-'' atmC [: / sec, which was extremely good.Also, in the comparative example, the one fired at 1700°C cleared, but
All items fired below 1600℃ -1,0-'atm
It was found that the practical level was not reached below CC/sec.

Note that the numbers in parentheses in the table indicate the parts by weight of the added powder relative to 1.00 parts by weight of the Mo and W powders.

〔Effect of the invention〕

According to the invention, calcium, strontium-6 or/and barium compounds, aluminum compounds and N1 in a tungsten or molybdenum base
or/and Cu metal or alloy.

By adding and mixing an oxide, the paste applied to the aluminum nitride sintered body can be fired in an inert atmosphere or a reducing atmosphere, and the Alx It is possible to obtain a tungsten or molybdenum metallized surface with a small decrease in thermal conductivity.

Claims (3)

[Claims] (1) In an aluminum nitride sintered body having a metallized surface, the metallized surface contains one or more members selected from the group consisting of copper, nickel, molybdenum, tungsten, alloys thereof, and compounds thereof, a calcium compound, An aluminum nitride sintered body having a metallized surface, characterized in that it contains one or more of the group consisting of strontium compounds, barium compounds, mixtures thereof, and solid solutions, and an aluminum compound. (2) A semiconductor device equipped with an aluminum nitride sintered body having a metallized surface according to claim 1. (3) One or two from the group consisting of copper, nickel, molybdenum, tungsten, and alloys and compounds thereof.
A metal paste prepared by kneading one or more of the group consisting of calcium compounds, strontium compounds, barium compounds, mixtures thereof, and solid solutions, an aluminum compound, and an organic binder is applied to the surface of the aluminum nitride sintered body. A method for producing an aluminum nitride sintered body having a metallized surface, the method comprising firing the aluminum nitride sintered body in an inert atmosphere or a reducing atmosphere to form a metalized layer on the surface of the sintered body.