JP2623868B2 - Substrate material for semiconductor devices with excellent heat dissipation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to aluminum nitride (hereinafter, referred to as AlN).
The present invention relates to a substrate material for a semiconductor device which has a thinner surface coating layer for forming a thick film circuit with respect to the surface of a base sintered substrate, and thus has more excellent heat dissipation.

[Conventional technology]

Conventionally, as a substrate material for a semiconductor device having excellent heat dissipation properties, for example, as described in JP-A-62-28847, a sputtering method, a sol-gel method, and a photochemical A surface coating layer made of silicon oxide (hereinafter, referred to as SiO ₂ ) is formed by a vapor deposition method or the like.
A substrate material formed with an average layer thickness of about 10 μm has been proposed, and a circuit is printed on the SiO ₂ surface coating layer surface of the substrate material using, for example, a conductive paste or a resistance paste,
By firing and repeating this process, a thick film circuit is formed and used as a substrate of a semiconductor device, which is in practical use.

[Problems to be Solved by the Invention] On the other hand, there is still a strong demand for higher performance and lighter and smaller electronic devices, and as a result, the degree of integration of hybrid modules increases, and as a result, heat generation also increases. even the substrate is required heat dissipation, thus also in the above-described conventional semiconductor device substrate material, especially compared thermal conductivity in ^{0.617cal · cm / sec · cm 2} · ℃ of AlN 0.004Cal
^{· Cm / sec · cm 2 ·} ℃ and as thin as possible a layer thickness relatively very low SiO ₂ surface-coating layer, tends to ensure a good heat dissipation, 0.05 the thickness of the SiO ₂ layer When the thickness is extremely thin as 1 μm, a circuit corresponding to the degree of integration is printed and formed on the surface of the SiO ₂ layer using, for example, a conductive paste or a resistive paste. now baking and forming the number of circuits is increased accordingly, AlN result circuit forming component through a thin SiO ₂ layer
Diffuses to the surface of the base sintered substrate and reacts with AlN of the AlN base sintered substrate to generate bubbles (N ₂ and NO ₂ ), which remain between the substrate surface and the thick film circuit. from not only reduce the adhesion of the thick film circuit to the substrate, thermal conductivity is lowered, since it becomes a problem such as causing heat dissipation reduction occurs, thinning of the SiO ₂ layer At present, it is difficult especially for a substrate of a highly integrated circuit.

[Means for solving the problem]

In view of the above, the present inventors focused on the above-described conventional semiconductor device substrate material and conducted research to reduce the thickness of the surface coating layer for forming a thick film circuit constituting the substrate material. As a result, the average layer thickness of the surface coating layer for forming a thick film circuit is 0.05 to 1 μm.
It is composed of an oxide solid solution containing boron oxide (hereinafter referred to as B ₂ O ₃ ): 5 to 50% by weight, with the balance being SiO ₂ and unavoidable impurities. On the other hand, a surface oxide layer is formed on the surface of the AlN-based sintered substrate with an average layer thickness of 0.2 to 15 μm. In this state, the above-mentioned surface coating layer for forming a thick film circuit,
Aluminum oxide (hereinafter, referred to as Al ₂ O ₃ ): 0.5 to 40% by weight between the surface oxide layer formed on the surface of the N-based sintered substrate, and zirconium oxide (hereinafter, ZrO ₂₎ ) And a thin layer composed of an oxide solid solution having a composition consisting of unavoidable impurities, with an average layer thickness of 0.05 to 1 μm, the base layer composed of this ZrO ₂ —Al ₂ O ₃ oxide solid solution The layer has a function of solid-solution capturing the thick film circuit forming component that has diffused and penetrated through the above-mentioned surface coating thin layer, and prevents the component from diffusing and moving to the surface oxide layer.
Since it does not react with the AlN of the AlN-based sintered substrate, and therefore, no bubbles are generated, a decrease in adhesion and thermal conductivity due to the remaining bubbles can be prevented, and the above-described diffusion-preventing base thin film can be prevented. The layer has excellent adhesion to the surface coating thin layer and the surface oxide layer of the substrate, and the B ₂ O ₃ component constituting the surface coating layer has excellent adhesion to repeated firing. Together with the effect of retaining, the research results showed that it would be possible to ensure excellent heat dissipation.

The present invention has been made on the basis of the above research results, and has an average layer thickness: 0.2 to 15 μm, Al ₂ O ₃ : 0.5 to 40% by weight on the surface of an AlN-based sintered substrate having a surface oxide layer. , And the remainder is composed of an oxide solid solution having a composition consisting of ZrO ₂ and inevitable impurities: 0.05 to 1 μm
An average layer thickness composed of an oxide solid solution containing B ₂ O ₃ : 5 to 50% by weight, with the balance being SiO ₂ and unavoidable impurities. 0.01-1 μm
This is characterized in that the substrate material for semiconductor devices having excellent heat dissipation properties is formed by forming the above-mentioned surface coating thin layer for forming a thick film circuit.

The AlN in the substrate material for a semiconductor device of the present invention
The group sintered substrate, Y ₂ O ₃ and one or two of CaO: containing 0.1% to 10%, is desirable to have a composition the remainder composed of AlN and unavoidable impurities, which, Y ₂ the O ₃ and CaO component, when the surface oxide layer formation, exhibit a very potent prooxidant effect, in a relatively short period of time, a predetermined thickness of the
In addition to the effect of forming a surface oxide layer mainly composed of Al ₂ O ₃ , it also has the effect of improving the sinterability during sintering of the sintered substrate and forming a high-strength sintered substrate. Therefore, if the content is less than 0.1%, the desired effect cannot be obtained in the above-described operation, while if it exceeds 10%, the thermal conductivity of the sintered substrate itself is reduced. Is preferably set to 0.1 to 10%.

The surface oxide layer on the surface of the AlN-based sintered substrate has an oxygen partial pressure of 10 ⁻² to 1 atm, a steam partial pressure of 10 ⁻³ atm or less, at a temperature of 1100 to 1500 ° C. Is formed by performing an oxidation treatment under the condition of heating and holding.

Furthermore, in the substrate material of the present invention, the average layer pressure of the surface oxide layer is determined to be 0.2 to 15 μm because the thickness is 0.2 μm.
If it is less than m, it is not only impossible to secure strong adhesion to the diffusion-preventing base thin layer, but also it is gradually contained in the diffusion-preventing base thin layer by repeated firing for forming a thick film circuit. The reaction between the circuit-forming component and the AlN of the AlN-based sintered substrate cannot be completely prevented, whereas when the thickness exceeds 15 μm, the thermal conductivity decreases. The average thickness of the diffusion-preventing base thin layer is determined to be 0.05 to 1 μm.
If the thickness is less than 0.05 μm, it is not possible to completely prevent the diffusion of the circuit-forming components diffused through the thin surface coating layer to the surface oxide layer. This is because the prevention effect saturates and rather causes a decrease in thermal conductivity. In this case,
By making ZrO _{2 a} solid solution containing Al ₂ O ₃ to form a ZrO ₂ -Al ₂ O ₃ oxide solid solution, the adhesion to the surface oxide layer and the surface coating thin layer is further improved, If the amount is less than 0.5%, the desired effect of improving the adhesion cannot be obtained, while if the content exceeds 40%, the diffusion preventing effect decreases, so the content must be 0.5 to 40%. . Further, the B ₂ O ₃ component constituting the surface coating layer has an action of maintaining a long-lasting high adhesiveness between the substrate and the surface coating layer against repeated firing during formation of a thick film circuit as described above. However, if the content is less than 5% by weight, the desired effect cannot be obtained in the above-mentioned action, while if the content exceeds 50% by weight, the content of SiO ₂ becomes relatively small, Since the adhesion to the thick film fired layer formed on the surface coating layer surface is reduced, the content is set to 5 to 50% by weight, and the average layer thickness is set to 0.01 to 1 μm. The reason is that if the thickness is less than 0.01 μm, the adhesion to the thick film fired layer formed on the surface is insufficient, while if the thickness exceeds 1 μm,
In particular, in the case of a high degree of integration, it is because sufficient heat dissipation cannot be exhibited.

Further, even when the substrate material of the present invention is used for manufacturing a single-layer substrate, further after forming a printed circuit thereon,
For example, a glass powder such as borosilicate glass is mixed with an organic binder to form a paste, and two or more sheets are stacked in a state where the paste is attached to the surface of the substrate by printing, and the stacked body of the substrates is at or above the softening point of the glass powder. It may be used as a multi-layer substrate formed by heating to a temperature, firing and bonding to each other.

〔Example〕

Next, the substrate material of the present invention will be specifically described with reference to examples.

First, AlN powder, Y ₂ O ₃ powder, and CaO powder each having an average particle size of 1 to ₃ μm are prepared as raw material powders, and these raw material powders are respectively blended into the composition shown in Table 1, After wet-mixing for 72 hours in a ball mill and drying, further add an organic binder to this and mix,
Formed into a green sheet by the doctor blade method, and then sintered at a temperature of 1800 ° C. for 2 hours in a nitrogen atmosphere at normal pressure, having substantially the same composition as the blended composition, and : 25.4 mm x 25.4 mm, thickness: 0.625 mm, manufactured an AlN-based sintered substrate, and then oxidized these substrates under the conditions shown in Table 1 to form a surface oxide layer. After formation, (a) Target material: ZrO ₂ sintered material with 99% purity,: ZrO
₂ oxides -1 wt% Al ₂ O ₃ solid solution sintered material, ZrO _2: 20 wt% oxide solid solution sintered material Al ₂ O _3, and ZrO ₂ -38 wt% A
l ₂ O ₃ oxide solid solution sintered material, target dimensions: diameter 3 mm × height 10 mm, power: 70 W, substrate rotation speed: 10 rpm, sputtering time: predetermined time, high frequency sputtering method under the following conditions: b) ZrO ₂ source solution obtained by mixing zirconium tetrabutoxide: 600 g with isopropyl alcohol: 1500 g;
Using an Al ₂ O ₃ source solution obtained by mixing isopropyl alcohol: 1500 g with alnium diisopropylate monobutyrate: 150 g, immersing the substrate in a mixed solution obtained by mixing these two solutions at an appropriate ratio, and pulling up the substrate. After repeating drying until a predetermined thickness is reached, the temperature is kept at 1000 ° C. for one hour in the air, and the sol-gel method under the conditions of firing is used. Forming a diffusion-preventing thin base layer having the composition and average layer thickness shown, and (i) target material: high-purity SiO ₂ sintered material having a purity of 99.9%, and oxidation of SiO ₂ -10 wt% B ₂ O ₃ Material-solid solution sintered material, and
SiO ₂ -30 wt% B ₂ O ₃ oxide solid solution sintered material, target dimensions: diameter 3 mm × height 10 mm, power: 100 W, substrate rotation speed: 10 rpm, sputtering time: predetermined time, (Ii) ethyl alcohol: 500 g and ethyl silicate: 25
0 g of SiO ₂ source solution and ethyl alcohol: 500
g to triethoxyborane: 100g a formed by mixing B ₂ O ₃ source solution, using the city, both of these solutions to a mixed solution obtained by mixing in an appropriate ratio, respectively, pulling by immersing the substrate, drying the predetermined thickness After repeating until the temperature becomes 1000 ℃
Sol-gel method under the condition of baking while holding for 1 hour, and forming the surface coating thin layer having the composition and average layer thickness shown in Table 1 by the method (i) or (ii) above. Materials 1 to 13 and comparative substrate materials 1 to 13 were manufactured, respectively.

Note that all of the comparative substrate materials 1 to 10 have at least one of the constituent requirements of the substrate material (marked with * in Table 1) out of the scope of the present invention. Reference numerals 13 to 13 correspond to conventional substrate materials.

Then, for the various substrate materials obtained as a result,
Ag-20% Pd alloy powder conductor on the surface Screen printing using a paste, temperature: after holding at 125 ° C for 10 minutes and drying, temperature: holding at 850 ° C for 10 minutes to form a paste fired layer, and conditions simulated for thick film circuit formation, That is, one cycle of holding at 850 ° C. for 10 minutes, the heating was repeated 9 times on the substrate material for forming the paste fired layer, the thermal conductivity was measured by a laser flash method, and a peeling test was performed. The peeling strength was measured, and the adhesion was evaluated.

In the peeling test, a diameter of 0.9 was formed on the fired layer of the substrate.
The oxygen-free copper wire bent in L-shape of mm is soldered at 215 ° C using Sn-Pb eutectic alloy solder, and this soldering wire is pulled in the direction perpendicular to the surface of the substrate, and the peeling at this time The measurement was performed by measuring the strength (peeling strength). Table 2 shows the measurement results.

〔The invention's effect〕

From the results shown in Tables 1 and 2, the substrate materials of the present invention 1 to 13
Has little change in thermal conductivity and peeling strength even after repeated baking heating, while showing a high value, as seen in Comparative substrate materials 1-13, any of the constituent requirements If the requirements deviate from the scope of the present invention, the desired high thermal conductivity and adhesion cannot be obtained, and further, the thermal conductivity is reduced by repeated firing heating, or the peeling strength is reduced, so that the desired superiority is obtained. It is clear that no high heat dissipation is exhibited and high reliability cannot be ensured.

As described above, the substrate material of the present invention has a thickness of the surface coating layer which is reduced by the diffusion-preventing base thin layer interposed between the surface coating layer for forming a thick film circuit and the surface oxide layer on the surface of the substrate. Even if it is extremely thin, the circuit forming components do not react with the AlN of the base to form bubbles due to repeated firing heating during the formation of a thick film circuit, so even when applied to a highly integrated semiconductor device substrate, Excellent heat conductivity and adhesion are secured, and it has industrially useful properties such as excellent heat dissipation.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tadaharu Tanaka 1-297 Kitabukurocho, Omiya City, Saitama Prefecture Mitsubishi Metals Central Research Laboratory (72) Inventor Yoshio Kanda 1-297 Kitabukurocho, Omiya City, Saitama Mitsubishi Metals Corporation Central Research Laboratory

Claims (1)

(57) [Claims] 1. The surface of an aluminum nitride-based sintered substrate having a surface oxide layer having an average layer thickness of 0.2 to 15 μm, containing 0.5 to 40% by weight of aluminum oxide, with the balance consisting of zirconium oxide and inevitable impurities. Average layer thickness composed of oxide solid solution with composition:
An average layer composed of an oxide solid solution containing boron oxide: 5 to 50% by weight through a 0.05 to 1 μm diffusion-preventing base thin layer, with the balance being silicon oxide and unavoidable impurities. Thickness: 0.01 ~
A substrate material for a semiconductor device having excellent heat dissipation formed by forming a surface coating thin layer for forming a thick film circuit of 1 μm.