JPH0834267B2 - Substrate material for semiconductor devices with excellent heat dissipation - Google Patents

Description

The present invention relates to an aluminum nitride (hereinafter, referred to as AlN) having good thermal conductivity and therefore excellent heat dissipation.
The present invention relates to a substrate material for a semiconductor device in which the adhesion of a silicon oxide (hereinafter referred to as SiO ₂ ) layer as a surface coating layer for forming a circuit to the surface of a base sintered substrate is extremely high.

[Conventional technology]

Conventionally, as a substrate material for a semiconductor device having excellent heat dissipation, for example, as described in JP-A-62-28847, a sputtering method, a sol-gel method, a photochemical method, or a photochemical method is used on the surface of a substrate made of an AlN-based sintered body. SiO ₂ by vapor deposition
A substrate material formed by forming a surface coating layer made of is proposed, and a circuit is printed on the surface of this SiO ₂ layer by using, for example, a conductor paste or a resistance paste, baked, and designed by repeating this. It is also known that a circuit is formed and used as a substrate of a semiconductor device for practical use.

[Problems to be Solved by the Invention]

However, with the recent trend toward higher performance, lighter, thinner, smaller, and smaller electronic devices, the degree of integration of hybrid modules tends to increase, and as a result, an increase in the amount of heat generated per unit cannot be avoided. In the above-mentioned conventional substrate material, although excellent heat dissipation can be ensured by the AlN sintered substrate having excellent thermal conductivity, the adhesion between the AlN sintered substrate and the SiO ₂ layer as the surface coating layer for circuit formation is not sufficient. Therefore, due to the increased heat radiation, peeling is apt to occur between them, which causes a problem in reliability.

[Means for solving the problem]

Therefore, the present inventors have considered that SiO ₂
As a result of research to improve the adhesion of the layer to the AlN sintered substrate, the substrate was selected from one of yttrium oxide (hereinafter referred to as Y ₂ O ₃ ) and calcium oxide (hereinafter referred to as CaO) or 2 types: 0.
An AlN-based sintered body containing 1 to 10% by weight and the rest consisting of AlN and unavoidable impurities was formed on the substrate. Oxygen partial pressure: 10 ^-2 to 1 atm, steam partial pressure When an oxidation treatment is performed under the conditions of heating and holding at a temperature of 1100 to 1500 ° C in an atmosphere of 10 ^-3 atm or less, Y ₂ O ₃ which is a constituent component of the substrate is
Since CaO and CaO exert an extremely strong oxidation-promoting effect, a dense surface oxide layer mainly consisting of aluminum oxide having a predetermined thickness is formed on the substrate surface in a short time. When a SiO ₂ layer as a surface coating layer for circuit formation is formed on the surface of the substrate, the SiO ₂ layer is firmly adhered and joined to the surface oxide layer, so that the SiO ₂ layer peels off due to heat generation. And Y ₂ O ₃ and
Since CaO also has the function of improving the sinterability of the AlN-based sintered compact of the upper atmosphere, the AlN-based sintered compact has a high purity, and this AlN-based sintered compact is the main constituent component of AlN It was found that they have high thermal conductivity and excellent heat dissipation.

The present invention has been made based on the above findings, and one or two kinds of Y ₂ O ₃ and CaO: 0.1 to 10 wt% is contained, and the balance is composed of AlN and inevitable impurities.
In addition, an AlN-based sintered substrate having an average layer thickness of 0.2 to 20 μm, and a surface coating layer for circuit formation having an average layer thickness of 0.01 to 10 μm, which is substantially composed of SiO ₂ , are formed on the surface of the substrate. It is characterized by a substrate material for semiconductor device having excellent heat dissipation.

Next, the reason for limiting the numerical values as described above in the substrate material of the present invention will be described.

(A) Content of Y ₂ O ₃ and CaO These components have the action of promoting oxidation and promptly forming a dense oxide layer on the surface portion of the substrate when the substrate is subjected to the oxidation treatment under the above conditions. In addition, it has the effect of improving the sinterability and the strength of the substrate, but its content is 0.
If the content is less than 1% by weight, the desired effect cannot be obtained, while if the content exceeds 10% by weight, the thermal conductivity of the substrate itself is reduced.
It was determined to be 0% by weight.

(B) Average thickness of surface oxide layer If the thickness is less than 0.2 μm, the adhesion of the SiO ₂ layer to the surface of the substrate becomes insufficient, while if it exceeds 20 μm, the excellent thermal conductivity of the substrate is achieved. The thickness is set to 0.1 to 20 μm, because the quality of the material is impaired.

(C) Average Layer Thickness of SiO ₂ Layer If the thickness is less than 0.01 μm, for example, the adhesion of the firing layer of the paste used for circuit printing to the substrate material is insufficient, while if the thickness exceeds 10 μm The thickness of the substrate is set to 0.01 to 10 μm, because the excellent heat dissipation by the substrate will be impaired.

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 printed on the surface of the substrate, and the stacked body of the substrates is at least the softening point of the glass powder. May be used as a multi-layer substrate formed by heating to the temperature described above, firing, and joining together.

〔Example〕

Next, the substrate material of the present invention will be specifically described by way of 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 under a normal pressure nitrogen atmosphere at a temperature of 1800 ° C. for 2 hours, to have substantially the same composition as the composition and a flat surface. : 25.4 mm x 25.4 mm, thickness: 0.625 mm, AlN-based sintered substrates were manufactured, and then these substrates were subjected to an oxidation treatment under the conditions shown in Table 1 to obtain a surface oxide layer. (A) Target material: high-purity quartz glass with a purity of 99.9%, target dimensions: diameter 3 mm x height 10 mm, power: 100 W, substrate rotation speed: 10 rpm, sputtering time: predetermined time (B) Ethyl silicate: 347g and ethyl alcohol:
500 g and a 0.3% HCl aqueous solution: 190.2 g mixed solution
Sprinkle the surface of the substrate rotating at 10 rpm for 10 seconds, temperature: 8
A sol-gel method consisting of holding at 00 ° C for 10 minutes and firing for 1 cycle, and repeating this until a predetermined thickness, (c) Si ₂ H ₆ / O ₂ = 0.015 in reaction gas: volume ratio : 0.2 torr, substrate temperature: 150 ° C light: light generated by mercury lamp, reaction time: predetermined time, photochemical vapor deposition method (photo-CVD method), Each of the substrate materials 1 to 14 of the present invention was manufactured by forming an SiO ₂ layer having an average layer thickness shown in Table 1 by any one of the above methods (a) to (c).

For comparison purposes, Y ₂ O ₃ and CaO
The conventional substrate materials 1 to 3 were each manufactured under the same conditions except that the AlN sintered substrate was manufactured without blending and the oxidizing treatment for forming the surface oxide layer was not performed on the AlN sintered substrate.

Next, for the various substrate materials obtained as a result,
Measure thermal conductivity by laser flash method,
A peeling test was performed to evaluate the adhesion between the substrate and the SiO ₂ layer.

The peeling test was carried out as shown in the schematic perspective view of FIG. 1, in which a SiO ₂ layer as a surface coating layer for circuit formation was formed in close contact with the surface of the substrate material 1, that is, the surface of the substrate 1a.
A conductor paste of Ag-20% by weight Pd alloy powder is screen-printed on 1b in a plane area of 2 mm × 2 mm, and the temperature is 125 ° C.
After holding it for 10 minutes to dry it, it is baked at a temperature of 850 ° C. for 10 minutes to form a paste baking layer 2, and then,
An oxygen-free copper wire 4 having a diameter of 0.9 mm was brazed on this using Sn-Pb eutectic alloy solder 3 at a temperature of 215 ° C. to obtain the state shown in the figure. Direction, and the peeling strength (peeling strength) at this time was measured. The results of these measurements are shown in Table 1.

〔The invention's effect〕

From the results shown in Table 1, the substrate materials of the present invention 1 to 14
Shows remarkably high thermal conductivity similar to the conventional substrate materials 1 to 3, and exhibits much higher peeling strength in a state where excellent heat dissipation is maintained, and the adhesion of the SiO ₂ layer to the substrate is extremely high. Is clear.

As described above, the substrate material of the present invention ensures extremely high adhesion with the SiO ₂ layer due to the surface oxide layer formed on the base-facing surface portion, and has a further excellent heat dissipation property due to the AlN sintered substrate. Therefore, the semiconductor device has industrially useful characteristics such that it can be sufficiently satisfied with the improvement of the integration degree of the semiconductor device.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a peeling test method. 1 ... Substrate material, 1a ... Substrate, 1b ... SiO ₂ layer, 2 ... Paste firing layer, 3 ... Solder, 4 ... Oxygen-free copper wire.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location H05K 1/03 630 J 7511-4E H01L 23/36 D (72) Inventor Hiroto Uchida Omiya City, Saitama Prefecture 1-297 Kitabukuro-machi, Central Research Laboratory, Mitsubishi Metals Co., Ltd. (72) Inventor Kenji Morinaga 1-297, Kitabukuro-cho, Omiya City, Saitama Prefecture (56) Reference, Central Research Laboratory, Mitsubishi Metals Co., Ltd. , A) JP 63-318760 (JP, A) JP 63-134694 (JP, A) JP 1-196149 (JP, A)

Claims (1)

[Claims] 1. A composition containing one or two of yttrium oxide and calcium oxide: 0.1 to 10% by weight, and the balance consisting of aluminum nitride and unavoidable impurities, and an average layer thickness of 0.2 to 20 μm. A semiconductor with excellent heat dissipation by forming a surface coating layer for circuit formation with an average layer thickness of 0.01 to 10 μm consisting essentially of silicon oxide on the surface of an aluminum nitride-based sintered substrate having a surface oxide layer. Substrate material for equipment.