JP2762007B2 - Metal thin film laminated ceramic substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal thin-film laminated ceramic substrate, and more particularly, to a thin film having fine film wiring formed on a ceramic substrate, having a strong film adhesion strength which is strong and excellent against thermal shock. And a metal thin-film laminated ceramic substrate used for an IC package and the like.

[0002]

2. Description of the Related Art Ceramics are members having excellent heat resistance, thermal shock resistance and high breaking strength, and are used in various fields. In the semiconductor industry, they are also used as IC packages and the like. However, ceramics are rarely used alone in the semiconductor industry or the like, and are used after being subjected to some kind of processing. For example, when used as an IC package, fine circuit wiring is formed of a metal thin film on a ceramic substrate, and a lead frame is joined.
Therefore, ceramics are often chemically processed and used. Further, the function of the ceramics can be sufficiently exhibited by firmly joining the ceramics and the metal.

[0003] In the case of joining ceramics and metal, it is difficult to join them directly. Conventionally, a method of once metallizing the surface of ceramics by a certain method and then joining a target metal thin film body is generally used. Has been adopted. In this method, a metallizing paste is screen-printed on the ceramic surface, and then heated in a reducing atmosphere, using a refractory metal method, or a metal with high chemical activity is physically vapor-deposited on the ceramic surface by sputtering. There is an active metal method of heating in an inert gas atmosphere, or a chemical vapor deposition method of heating a metal in a vacuum and attaching vapor generated at that time.

FIG. 5 is a schematic cross-sectional view of a metal thin film laminated ceramics substrate conventionally used for an IC package or the like.
Shown in In the figure, reference numeral 12 denotes a ceramic substrate,
A first metal thin film layer 23 made of Ti or the like formed on the surface of the ceramic substrate 12 by the above method, and a second metal thin film layer 2 made of Mo, Ni, etc. on the first metal thin film layer 23
4. A third metal thin film layer 25 made of Ag, Cu or the like is formed on the second metal thin film layer 24 by a chemical vapor deposition method or a physical vapor deposition method, and a plating film layer formed by electrolytic plating of Cu or the like as the outermost layer. 26, the first metal thin film layer 23, the second metal thin film layer 24, and the third metal thin film layer 2
5 and the plating film layer 26, a metal thin film laminate 27 is formed.
2 constitute a metal thin film laminated ceramics substrate 21.

[0005]

SUMMARY OF THE INVENTION LSI devices having a size of 35 μm
TAB on which a Cu wiring pattern with a thickness of
In the case of mounting on utomated bonding, it is necessary that TAB does not cause disconnection of Cu wiring in an LSI peeling test. To this end, it is said that in a peel test for measuring the adhesion strength of the film, it is necessary that the value of the adhesion strength of the film be 2 kg / mm ² or more. It is said that the same film adhesion strength is required for metal thin film laminated ceramics substrates, but in consideration of reproducibility and reliability due to changes in conditions during thin film formation, actually higher film adhesion strength is required. Is desired. Further, it is required that the adhesive strength of the thin film does not deteriorate due to thermal shock.

However, in the conventional metal thin film laminated ceramic substrate 21 having the above-described structure, the film adhesion strength is not sufficient, and the value of the film adhesion strength by the peel test is 3
There is a problem that there is hardly any exceeding kg / mm ^{2 and} that deterioration due to thermal shock is large.

That is, the conventional metal thin-film laminated ceramic substrate 21 can be used in a high-temperature heat test or a high-temperature holding test.
The first metal thin film layer 23 passes through the second metal thin film layer 24 which should serve as a barrier layer and the third metal thin film layer 25
, And the surface of the third metal thin film layer 25 turns black, and as a result, the film adhesion strength of the plating film layer 26 formed by electrolytic plating is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has the following advantages: a first metal layer is prevented from diffusing into an upper layer; a high peel strength of 3 kg / mm ² or more; It is an object of the present invention to provide a metal thin film laminated ceramic substrate having excellent impact properties.

[0009]

In order to achieve the above object, a metal thin film laminated ceramic substrate according to the present invention is a metal thin film laminated ceramic substrate comprising a ceramic substrate and a plurality of metal thin films laminated thereon. VIA excluding group IVA or Mo on the periodic table
Metal thin-film layer made of at least one element selected from the group consisting of at least one element selected from the group consisting of:
A second metal thin film layer made of at least one element selected from the group IA or Ni, and a periodic table IB on the second metal thin film layer
A third metal thin-film layer made of at least one element selected from the group consisting of: a fourth metal thin-film layer made of the same element as the second metal thin-film layer on the third metal thin-film layer; A fifth metal thin film layer made of the same element as that of the third metal thin film layer.

[0010]

According to the metal thin film laminated ceramic substrate according to the present invention, in a metal thin film laminated ceramic substrate in which a plurality of metal thin films are laminated on a ceramic substrate, a group IVA or Mo of the periodic table is formed on the ceramic substrate. Excluding the first one or more elements selected from the VIA group
A metal thin film layer, a second metal thin film layer made of at least one element selected from Group VIA or Ni except for Cr and W on the first metal thin film layer, and a second metal thin film layer on the second metal thin film layer A third metal thin film layer made of at least one element selected from Group IB of the periodic table; a fourth metal thin film layer made of the same element as the second metal thin film layer on the third metal thin film layer; Since the fifth metal thin film layer made of the same element as the third metal thin film layer is stacked on the fourth metal thin film layer, the diffusion of the first metal thin film layer is prevented, and the fifth metal thin film layer is stacked on the ceramic substrate. Metal thin film laminated body and each metal thin film layer in the metal thin film laminated body are firmly bonded, and 3 kg / m
It has a film adhesion strength of at least m ^{2 and} its bond does not deteriorate even when subjected to thermal shock.

In the above structure, the first metal thin film layer made of at least one element selected from Group IVA or VIA of the periodic table is formed on the surface of the ceramic substrate. The thin film layer has high activity with respect to the ceramic substrate, and is easily diffused into the ceramic substrate, so that the thin film layer is firmly bonded to the ceramic substrate, and a group VIA of the periodic table formed on the first metal thin film layer. Alternatively, it is easily diffused into the second metal thin film layer made of at least one element selected from Ni, and is also strongly bonded to the second metal thin film layer.

Examples of the ceramic substrate include an oxide-based ceramic substrate such as alumina, and a non-oxide-based ceramic substrate such as aluminum nitride and silicon carbide. This is effective when a problematic alumina substrate is used. The metal used for the first metal thin film layer may be Ti, Zr, Cr
And the like. Examples of the metal used for the second metal thin film layer include Mo, Ni, and the like. Particularly, when Ti is used for the first metal thin film layer, alumina and an intermetallic compound are easily formed, so that the metal is strong. In addition, Mo and the like are also strongly bonded because they easily form an alloy.

Next, a laminated film formed on the second metal thin film layer will be described. The second metal thin film layer and the fourth metal thin film layer are made of the same metal, and Periodic Table I between the thin film layer and the fourth metal thin film layer
It employs a so-called sandwich structure in which a third metal thin film layer made of at least one element selected from Group B is interposed. By adopting the sandwich structure, the first metal thin film layer of Ti or the like mainly forms a solid solution in the IB element while diffusing the third metal thin film layer, and passes through these layers to form the first metal thin film layer. It does not diffuse to the five metal thin film layers, and prevents the deterioration of the film adhesion strength of the outermost plating film layer due to the diffusion of the first metal thin film layer.

The metal used for the third metal thin film layer includes, for example, Cu, Au, Ag and the like. The fifth metal thin film layer is also made of the same metal as the third metal thin film layer.

By forming the metal thin film laminate in which the sandwich structures of different kinds of metals are stacked in this manner, the metal thin film layers are diffused with each other, and the thin film layers are firmly bonded to each other. In addition, the metal thin film laminated ceramic substrate having high film adhesion strength is firmly bonded to the ceramic substrate.

[0016]

Examples and Comparative Examples Examples of a metal thin film laminated ceramic substrate according to the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a schematic sectional view showing the structure of a metal thin film laminated ceramic substrate according to Embodiment 1. In the figure, reference numeral 12 denotes a ceramic substrate,
a first metal thin film layer 13 made of Ti on the surface of a ceramic substrate 12 made of l ₂ O _{3; a} second metal thin film layer 14 made of Mo on the first metal thin film layer 13; A third metal thin film layer 15 made of Cu, a fourth metal thin film layer 16 made of Mo on the third metal thin film layer 15, and a fifth metal thin film layer 1 made of Cu on the fourth metal thin film layer 16.
7. Cu on the fifth metal thin film layer 17 as an outermost layer
The first metal thin film layer 13, the second metal thin film layer 14, the third metal thin film layer 15,
The metal thin film laminate 19 is formed by the fourth metal thin film layer 16, the fifth metal thin film layer 17, and the plating film layer 18, and the metal thin film laminate 19 and the ceramic substrate 12 constitute the metal thin film laminated ceramic substrate 11. I have.

Next, the metal thin film laminated ceramic substrate 11
Will be described. First, the first metal thin-film layer 13 is formed on the surface of the ceramic substrate 12 made of Al ₂ O ₃ by chemical vapor deposition or physical vapor deposition using Ti having a high chemical activity and easily reacting with Al ₂ O ₃ . 05-0.20
It is formed to a thickness of μm. At this time, Ti is the lower Al ₂ O ₃
Reacts with the ceramic substrate 12 made of to form an intermetallic compound.

A second metal thin film layer 14 made of Mo is formed on the first metal thin film layer 13 by chemical vapor deposition or physical vapor deposition.
A third metal thin film layer 15 made of Cu and a fourth metal thin film layer 16 made of Mo are formed. The thickness of the second metal thin film layer 14 is 0.10 to 0.20 μm, the thickness of the third metal thin film layer 15 is 0.01 to 0.02 μm, and the thickness of the fourth metal thin film layer 16 is 0.10 to 0.10 μm. Each was set to 0.30 μm. This second
The metal thin film layer 14, the third metal thin film layer 15, and the fourth metal thin film layer 16 serve as barriers for preventing the first metal thin film layer 13 from seeping into the fifth metal thin film layer 17. The third metal thin film layer 15 is preferably a thin layer having a thickness of 0.01 to 0.02 μm. If the third metal thin film layer 15 is thicker, the film adhesion strength tends to decrease.

The fifth metal thin film layer 17 is formed on the fourth metal thin film layer 16 by chemical vapor deposition or physical vapor deposition using Cu having good conduction resistance to a thickness of 0.20 to 0.50 μm. . Thereafter, a plating film layer 18 having a thickness of 3 to 4 [mu] m is formed by a chemical plating method so as to enhance the conduction effect and make it versatile. This plating film layer 18
Is formed using an IB group element that is the same as the fifth metal thin film layer 17.

The film thickness from the first metal thin film layer 13 to the plating film layer 18 is a desirable value when it is intended to form a fine circuit wiring and to be used for an IC package. Can be changed.

As the physical vapor deposition method, a general known method can be used, for example, a vacuum vapor deposition method, an ion beam vapor deposition method, a sputtering method, or the like, which is characterized in that the material and the film thickness can be freely selected. have. In addition, a general known method can be used for the chemical plating method for forming the uppermost layer, and examples thereof include an electrolytic plating method and an electroless plating method.

The following Tables 1, 2 and 3 show the metal thin film laminated ceramics according to Example 1 and another example manufactured by changing the kind of metal constituting the metal thin film laminate 18 in Example 1 described above. 9 shows the results of measuring the film adhesion strength of a substrate and a metal thin-film laminated ceramic substrate according to a comparative example composed of a conventional metal thin film layer. The measurement result of the film adhesion strength is different from the normal case where the peel test is performed and +15
After performing a heat cycle of 0 ° C./−60° C. for 30 minutes each, 200 cycles at a temperature rise / fall rate of 10 ° C./min, the Ni lead wire 2
2 was subjected to a peel test (in the table, indicated as after thermal cycling).

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

In Examples and Comparative Examples shown in Tables 1, 2 and 3, a solder pull test as shown in FIG. 2 was carried out as a method for measuring the film adhesion strength by a peel test. First, N 1 having a diameter of about 1 mm is placed on a metal thin film laminated ceramics substrate 11.
The i-lead wire 22 was soldered, and then pulled vertically at a rate of 10 mm per minute for each pin to break it, and the strength at the time of breaking was defined as the film adhesion strength. At this time, the breakage of the solder and the breakage of the interface between the solder and the metal thin film were deleted from the data because they could not be evaluated as proper film strength.

As is clear from Tables 1, 2 and 3, the films of Comparative Examples 1 to 18 have a normal film adhesion strength of 3 kg / m.
m ² or more shows the value also was present, the intensity measured to film adhesion strength after thermal shock reliability tests are degraded,
No other samples showed a value of 3 kg / mm ² or more, and deterioration of the film adhesion strength due to thermal shock was observed.

On the other hand, those of Examples 1 to 18 exhibited stable strength even after the thermal shock reliability test, and a film adhesion strength of 3 kg / mm ² or more was obtained.

Next, using the metal thin-film laminated ceramic substrates obtained in Example 1 and Comparative Example 1, a heat treatment was performed at 850 ° C. for 10 minutes, and a surface analysis was performed using EPMA. The results are shown in FIGS. 3 and 4, the vertical axis indicates the diffraction intensity, and the horizontal axis indicates the diffraction angle. As is clear from the results, titanium was not detected on the surface of the metal thin-film laminated ceramic substrate used in Example 1, whereas titanium was detected on the surface of the metal thin-film laminated ceramic substrate obtained in Comparative Example 1. It can be seen that the titanium atoms have been thermally diffused to the surface.

When the metal thin-film laminated ceramic substrates of Example 1 and Comparative Example 14 were subjected to a heat treatment at 600 ° C. for 2 hours before being subjected to electrolytic plating, the substrate of Example 1 showed no discoloration. Comparative Example 1
4 turned brown. From these results, it can be seen that in the conventional example, Ti is easily diffused into the surface layer by heat treatment, whereas in the example, thermal diffusion of Ti is prevented.

This is presumed to be due to the following reasons. Since the Ti of the first layer is very reactive and active,
First, the Ti is diffused into Mo of the second layer by heat treatment. Ti is further diffused into Cu of the third layer and is dissolved in Cu. Since Ti and Cu are easily dissolved in each other, Cu
Is easily formed into a solid solution even if the film thickness is as thin as about 0.01 μm. Ti that could not be completely dissolved in Cu
Although it is diffused into the Mo of the layer, its amount is so small that it does not pass through its fourth layer. Therefore, the metal thin-film laminated ceramic substrate of Example 1 prevents heat diffusion to the surface of Ti even when heat treatment is performed. This inference has been confirmed by SIMS analysis in the depth direction.

As described above, in the metal thin-film laminated ceramic substrate according to the embodiment, even in the high temperature state, the first
Since the metal thin film layer 13 does not diffuse to the surface layer, it is considered that the film adhesion strength does not deteriorate even after the thermal shock test.

[0034]

As described in detail above, in the metal thin film laminated ceramic substrate according to the present invention, a metal thin film laminated ceramic substrate in which a plurality of metal thin films are laminated on a ceramic substrate is provided. A first metal thin film layer made of at least one element selected from Group IVA or Group VIA other than Mo, and a group VIA of the Periodic Table other than Cr and W on the first metal thin film layer; A second metal thin film layer made of at least one element selected from Ni, a third metal thin film layer made of at least one element selected from Group IB of the periodic table on the second metal thin film layer, The fourth metal thin film layer having the same element as the second metal thin film layer
Since the fifth metal thin film layer made of the same element as the third metal thin film layer is laminated on the metal thin film layer and the fourth metal thin film layer, the diffusion of the first metal thin film layer can be prevented. The ceramic substrate and the metal thin film laminate and each metal thin film layer in the metal thin film laminate can be firmly bonded, and as a result, have a film adhesion strength of 3 kg / mm ² or more in a peel test, It is possible to provide a metal thin film laminated ceramics substrate in which the film adhesion strength does not change even when subjected to this.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a metal thin-film laminated ceramic substrate according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a method of measuring film adhesion strength by a peel test.

FIG. 3 is a graph showing the result of elemental analysis of the surface of the metal thin-film laminated ceramic substrate obtained in Example 1 after the surface thereof was heat-treated using EPMA.

FIG. 4 is a graph showing the result of elemental analysis of the surface of the metal thin-film laminated ceramic substrate obtained in Comparative Example 1 using EPMA after heat treatment.

FIG. 5 is a schematic sectional view showing a conventional metal thin film laminated ceramics substrate.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 metal thin film laminated ceramic substrate 12 ceramic substrate 13 first metal thin film layer 14 second metal thin film layer 15 third metal thin film layer 16 fourth metal thin film layer 17 fifth metal thin film layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Miki 4-5-33 Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries Co., Ltd. 2701 No. 1 Sumitomo Metal Ceramics Co., Ltd.

Claims (1)

(57) [Claims] 1. A metal thin film laminated ceramic substrate having a plurality of metal thin films laminated on a ceramic substrate, wherein at least one member selected from Group IVA of the periodic table or Group VIA excluding Mo on the ceramic substrate. A first metal thin-film layer made of the following elements: on the first metal thin-film layer, VIA of the periodic table excluding Cr and W
A second metal thin-film layer made of one or more elements selected from Group III or Ni; a third metal thin-film layer made of one or more elements selected from Group IB of the periodic table on the second metal thin film layer; A fourth metal thin film layer made of the same element as the second metal thin film layer on the third metal thin film layer; a fifth metal thin film made of the same element as the third metal thin film layer on the fourth metal thin film layer A metal thin-film laminated ceramic substrate, wherein the layers are laminated.