JPH0723273B2 - Method for metallizing aluminum nitride substrate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a metallization method for an aluminum nitride substrate, which is suitable for manufacturing a semiconductor element substrate or the like in which a metal layer is formed on an aluminum nitride sintered body. Is.

(Problems to be Solved by Conventional Techniques and Inventions) Alumina porcelain has generally been used for conventional insulating substrate components such as semiconductor substrates, IC substrates, and various insulating components.

However, in recent years, a multilayer ceramic substrate has been required as a mounting substrate for a high-speed LSI having a high integration density.
As a result, higher heat is applied to the mounting board with higher integration density of the circuit, and a ceramic board with higher thermal conductivity, that is, a board with good heat dissipation is required.
Aluminum nitride sintered substrates have appeared.

Aluminum nitride has a thermal conductivity of about 3 to about that of alumina.
It is four times or more, has a coefficient of thermal expansion about half that of alumina, and has excellent characteristics such as strength not much different from alumina and beryllia.

By the way, it is necessary to metallize a part of the surface of semiconductor substrates, IC substrates, etc., and many metallizing methods have been proposed.

Conventionally, many excellent methods such as a molybdenum-manganese method have been developed as a method for metallizing an alumina ceramic substrate, but a metallization method for a non-oxide ceramic has not been so much developed.

In particular, the aluminum nitride sintered body has poor wettability, and it is difficult to form a strong metallized layer for it, and various researches and technological developments are currently underway.

As a recently known one, for example, an aluminum nitride substrate on which a circuit is formed by a thick film paste containing at least one of Pb and Si is disclosed in JP-A-61-84089, but the adhesion strength is 2 kg / mm. ^It is as low as ² or less, and there is a problem that it is difficult to form a fine pattern because the circuit is formed by screen printing.

Also, for example, W, W-Mo, A formed with a W-Pt-based metallization layer
An lN multilayer substrate is disclosed in Japanese Patent Laid-Open No. 60-253294, and an AlN substrate surface containing at least one of Y, rare earths and alkaline earth metals is used as a conductive paste of at least one of Au, Ag-Pd and Cu. A circuit board having a formed conductor path is disclosed in JP-A-60-
It is described in Japanese Patent No. 178688.

However, in the invention described in JP-A No. 60-253294, W, Mo, Pt alone or an alloy is metalized with respect to AlN using CaC ₂ as a sintering aid, but the adhesion is described. In the invention of JP-A-60-253294, the inventor of the present application considers that the metallized adhesion is at a considerably low level.

Further, in the invention described in the latter JP-A-60-178688, the adhesion strength of the metallized layer was 1.95 kg / mm ² (Max 2.3 kg / mm ² ), Ag-Pd when Au paste was used. In case of 1.65kg / mm ² (Max2.1kg / mm ² ), Cu is 1.4
It is 2kg / mm ₂ (Max 1.9kg / mm ² ) and the adhesion strength is not satisfactory. Au, Ag-Pd, Cu-based thick film paste is bonded by glass or by forming a compound, but such bonding method does not have such strong adhesion, and only on the baked substrate. It is possible to form a circuit, and it is not possible to produce a multilayer circuit board.

Furthermore, a method of using W + AlN as a metallizing paste has been proposed, but the adhesion strength is relatively high at ² kg / mm ² , but the sheet resistance is 20 mΩ / □ (min) to 30 mΩ (m
ax), which is about twice that of conventional alumina and is not satisfactory.

(Means for Solving the Problems) As a result of further research in view of the above circumstances, the present inventor further improved the adhesion strength of the thick film metallized layer in the co-firing method,
In addition, a method of forming a W metallized layer with reduced sheet resistance on an aluminum nitride substrate was developed.

The present invention makes it possible to obtain a good W by providing a specific aluminum nitride composition as the aluminum nitride forming body.
It is characterized in that it can form a metallization, that is, it is mainly composed of AlN, and calcium compounds and yttrium compounds are converted into CaO and Y ₂ O ₃ conversions and shown in the attached FIG. 1, point A (CaO: 0.01 % By weight, Y ₂ O ₃ : 12% by weight), B (CaO: 1.8% by weight, Y ₂ O ₃ : 12% by weight), C (CaO: 1.8% by weight, Y ₂ O ₃ : 10% by weight), D (CaO: 2.7% by weight, Y ₂ O ₃ : 10% by weight), E (CaO: 2.7% by weight, Y ₂ O ₃ : 3% by weight), F (CaO: 3.5% by weight, Y ₂ O ₃ : 3% by weight) %), G (CaO: 3.5% by weight, Y ₂ O ₃ : 0.01% by weight), H (CaO: 0.01% by weight, Y ₂ O ₃ : 0.01% by weight), within the range enclosed by the line connecting A The method for metallizing an aluminum nitride substrate is characterized in that a W metallizing paste is applied to the surface of the aluminum nitride green body which is contained in an amount of 0.1 to 2100 ° C. and baked at 1400 to 2100 ° C. According to this method, a W metallization having an adhesion strength of 2 kg / mm ² or more is formed. Further, in order to obtain a W metallized layer having an improved adhesion strength, the composition range of the green compact is shown in FIG. 1 attached, point A (CaO: 0.01% by weight, Y ₂ O ₃ : 12% by weight), I (CaO: 0.33% by weight, Y ₂ O ₃ : 12.0% by weight), P (C
aO: 0.33% by weight, Y ₂ O ₃ : 10.8% by weight), J (CaO: 1.8% by weight, Y ₂ O ₃ : 10.8% by weight), C (CaO: 1.8% by weight, Y ₂ O ₃ : 10)
Wt%), K (CaO: 2.7 wt%, Y ₂ O ₃ : 5.2 wt%), E
(CaO: 2.7% by weight, Y ₂ O ₃ : 3% by weight), F (CaO: 3.5% by weight, Y ₂ O ₃ : 3:% by weight), G (CaO: 3.5% by weight, Y ₂ O ₃ : 0.01% by weight) %), H (CaO: 0.01% by weight, Y ₂ O ₃ : 0.01% by weight), A
You can select one within the range surrounded by the line segment connecting
In this case, adhesion strength of 3 to 3.5 kg / mm ² or more can be secured.

Further, as shown in the attached FIG. 1, points N (CaO: 0.01% by weight, Y ₂ O ₃ : 9.0% by weight), O (CaO: 1.65% by weight, Y ₂ O ₃ : 9.0%).
Wt%), E (CaO: 2.7 wt%, Y ₂ O ₃ : 3 wt%), L (C
aO: 2.7% by weight, Y ₂ O ₃ : 0.8% by weight), M (CaO: 0.01% by weight, Y ₂ O ₃ : 0.8% by weight), within the range surrounded by the line segment The adhesive strength is 3.5 kg / mm ² or more.

The W metallizing paste is prepared by simply adding and mixing an organic binder, a solvent, and the like, which are usually used for tungsten powder, to have a required viscosity.

The application of the metallized paste on the AlN generation body is
Usually, it is carried out so as to form a predetermined pattern by the screen printing method.

The metallization firing temperature is preferably in the range of 1400 ° C to 2100 ° C, and if it is lower than the lower limit or exceeds the upper limit, the adhesion strength of the metallized layer becomes very weak and it is not practical.

The co-firing atmosphere with the W metallization is preferably a non-oxidizing atmosphere, and in the oxidizing atmosphere, aluminum nitride is oxidized or W is oxidized to become a high resistance element, and therefore sheet resistance becomes very high, which is not preferable.

Usually, on the W metallized layer on the aluminum nitride substrate on which the W metallized layer is formed by the method of the present invention,
A conductor layer is further provided to form a semiconductor circuit board.

As the conductor layer, for forming a fine pattern of the metallized circuit, similar to the conventional method, for example, Ni, Co, Cu, Au, Ag, Pd,
Pt or the like is formed by plating, brazing or the like.

As described above, according to the method of the present invention, since the adhesion strength of the W metallized layer on the surface of the aluminum nitride substrate is 2 kg / mm ² or more and is strong, it becomes possible to form a metallized circuit fine pattern. Multilayering is possible.

Moreover, the sheet resistance of the metallized layer formed is low (20
Since it is less than mΩ / □, but the thickness of the W layer is 20 μm), it is possible to form an excellent fine pattern of a metallized circuit with a small amount of heat generation.

The sheet resistance is as shown in FIG. 2, and according to the method of the present invention, a sheet resistance of 20 mΩ / □ or less can be obtained. Especially Y ₂ O ₃ , C
In the case of using an aluminum nitride forming body whose content range is surrounded by A-B-C-R-Q-H-A in terms of aO, 10
It is possible to provide a W metallization layer having a low sheet resistance of ~ 15 mΩ / □ or less.

Further line S-C-T-H- S [ segment S (Y ₂ O _3: 10.0 wt%, CaO: 0.01 _{wt%) - C (Y 2 O} 3: 10.0 wt%, CaO: 1.8% by weight) -T (Y ₂ O _3: 0.01 wt%, CaO: 1.8 wt%) - H (Y
₂ O ₃ : 0.01 wt%, CaO: 0.01 wt%)-S] When using the Y ₂ O ₃ , CaO-containing AlN substrate in the range, 10 mΩ /
□ The following W metallization layer having a lower sheet resistance can be provided.

(Example) Next, the present invention will be described with reference to an example.

Example 1: AlN powder having an average particle size of 1.4 μm and Y ₂ O ₃ having an average particle size of 0.8 μm
12% by weight of powder and 0.03% by weight of 1.3 μm CaCO ₃ powder were added, pulverized and mixed using a ball mill to prepare a raw material for the substrate.

Next, after adding 10% by weight of polymethacrylate to this raw material and kneading, 45 mm x 45 mm by the doctor blade method
A × 3 mm raw sheet laminated body was prepared.

W powder (average particle size 1.
3 μm) Wet-mill 100 g in acetone, then add and mix 2 parts by weight of ethyl cellulose and 15 parts by weight of butyl carbidol and volatilize acetone to obtain a W metallized paste composition. Printed with and dried, 88% N ₂ + 12% H ₂
By heating at 1680 ° C for 1 hour in the atmosphere, the aluminum nitride substrate, which became a sintered body by simultaneous firing,
A 20 μm thick W metallization layer was formed.

As a result of the test, the adhesion strength of this metallized layer is 3.1 kg / mm ²
It was found that the adhesive strength was high. The sheet resistance was low at 10.8 mΩ / □.

Examples 2 to 22 In the same manner as in Example 1, the W metallizing paste was applied on the aluminum nitride production form containing the amounts of CaO and Y ₂ O ₃ sintering aids described in Sample Nos. 3 to 28 of Table 1. After printing by printing with a thickness of 24 μm, after drying, it was heated at 1680 ° C. in an atmosphere of 88% N ₂ + 12% H ₂ for 1 hour to be metallized.

The results of the test are shown in Table 1, and the adhesion strength of the W metallized layer is 2.3 kg / mm ² or more, and the particularly good one has a very high adhesion strength of up to 5.0 kg / mm ^2. Is.

The sheet resistance was 5.8 to 16.9 mΩ / □, which was low.

Comparative Example: (Sample Nos. 23 to 28) On an aluminum nitride substrate containing CaO and Y ₂ O ₃ sintering aids described in Sample Nos. 23 to 28 of Table 1, Example 1 (on an aluminum nitride green sheet). W metallizing treatment), print the W metallizing paste with a thickness of 24 μm, dry it, and dry it in an atmosphere of 88% N ₂ + 12% H ₂ for 16
Metallization was performed by heating at 80 ° C for 1 hour.

The test results of the above Examples and Comparative Examples are as shown in Table 1, and in the case of the metallizing method of Sample Nos. 1 to 28 in the scope of the present invention, the adhesion strength of the obtained metallized layer was 2.3 to The value was 5. kg / mm ² , which was very good.

The sheet resistance was also very low at 16.9 to 5.8 mΩ / □, which was preferable.

On the other hand, in the case of the comparative examples of the sample numbers 23 to 28 outside the scope of the present invention, the adhesion strength of the obtained metallized layer was 3.2 to 1.6.
kg / mm ^2, the sheet resistance is 27~9.5mΩ / □ a, or adhesion strength sheet resistance is low and one good low the other is intended to not be satisfied In the relationship, such as poor. The method of measuring the adhesion strength between the substrate and the W metallized layer was as follows. A W metallized pad of 2 mm □ was formed on an aluminum nitride substrate under the conditions of Examples, Ni was plated on this, and sintered at 800 ° C. 0.8mmφ Ni wire is brazed with silver at ℃,
It was based on the strength test by the vertical tension method.

(Effects of the Invention) As described in the above examples and the like, according to the method of the present invention, the adhesion strength between the aluminum nitride substrate and the W metallization layer can be made very high, so that fine pitch can be achieved on the substrate. Can form a strong metallized circuit pattern, and the sheet resistance is also quite low,
The heat generation amount of the entire semiconductor package and the like can be reduced at the same time.

[Brief description of drawings]

FIG. 1 is a relationship diagram showing the adhesion strength of the metallized aluminum nitride substrate according to the present invention, and FIG. 2 is a relationship diagram showing the sheet resistance of the metallized aluminum nitride substrate according to the present invention.

Claims (5)

[Claims] 1. The main component is AlN, and calcium compounds and yttrium compounds are converted into CaO and Y ₂ O ₃ and shown in FIG. 1 attached. Point A (CaO: 0.01 wt%, Y ₂ O ₃ : 12 wt %) B (CaO: 1.8% by weight, Y ₂ O ₃ : 12% by weight) C (CaO: 1.8% by weight, Y ₂ O ₃ : 10% by weight) D (CaO: 2.7% by weight, Y ₂ O ₃ : 10) Wt%) E (CaO: 2.7 wt%, Y ₂ O ₃ : 3 wt%) F (CaO: 3.5 wt%, Y ₂ O ₃ : 3 wt%) G (CaO: 3.5 wt%, Y ₂ O ₃ : 0.01% by weight) H (CaO: 0.01% by weight, Y ₂ O ₃ : 0.01% by weight) W metallizing paste is applied to the surface of the aluminum nitride forming body, which is contained within the range surrounded by the line connecting A. And a method for metallizing an aluminum nitride substrate, which comprises firing at 1400 to 2100 ° C. 2. A calcium compound and a yttrium compound are converted to CaO and Y ₂ O ₃ and shown in FIG. 1 attached, point A (CaO: 0.01% by weight, Y ₂ O ₃ : 12% by weight) I ( CaO: 0.33% by weight, Y ₂ O ₃ : 12% by weight) P (CaO: 0.33% by weight, Y ₂ O ₃ : 10.8% by weight) J (CaO: 1.8% by weight, Y ₂ O ₃ : 10.8% by weight) C (CaO: 1.8 wt%, Y ₂ O ₃ : 10 wt%) K (CaO: 2.7 wt%, Y ₂ O ₃ : 5.2 wt%) E (CaO: 2.7 wt%, Y ₂ O ₃ : 3 wt%) F (CaO: 3.5% by weight, Y ₂ O ₃ : 3% by weight) G (CaO: 3.5% by weight, Y ₂ O ₃ : 0.01% by weight) H (CaO: 0.01% by weight, Y ₂ O ₃ : 0.01% by weight) ) A method of metallizing an aluminum nitride substrate according to claim 1, characterized in that the amount is contained within a range surrounded by a line segment connecting A. 3. A calcium compound and a yttrium compound are converted to CaO and Y ₂ O ₃ and shown in FIG. 1 attached, point N (CaO: 0.01 wt%, Y ₂ O ₃ : 9 wt%) O ( CaO: 1.65% by weight, Y ₂ O ₃ : 9% by weight) E (CaO: 2.7% by weight, Y ₂ O ₃ : 3:% by weight) L (CaO: 2.7% by weight, Y ₂ O ₃ : 0.8% by weight) M (CaO: 0.01% by weight, Y ₂ O ₃ : 0.8% by weight) The metallization of the aluminum nitride substrate according to claim 1, characterized in that the content is within a range surrounded by a line segment connecting N. Method. 4. The method for metallizing an aluminum nitride substrate according to claim 1, further comprising a conductor layer provided on the W metallized layer on the aluminum nitride substrate. . 5. The method for metallizing an aluminum nitride substrate according to claim 4, wherein the conductor layer is one or more of Ni, Co, Cu, Au, Ag, Pd and Pt. .