JPH05191018A - Manufacture of ceramic wiring board - Google Patents

Abstract

PURPOSE:To form a metal wiring layer, having a fine and complicated pattern, on a ceramic board in an excellent reproducible manner at low cost. CONSTITUTION:A resist pattern 2 is formed on the part excluding the part where desired wiring pattern is formed on a ceramic board 1. A soldering material layer 3, containing an activated metal component, is formed on the part where wiring pattern is to be formed on the ceramic board by performing a thin film forming method using the resist pattern 2 as a shielding material. A resist film is removed. A metal wiring board in wiring pattern form is arranged by lamination on the soldering material layer 3, the ceramic board 1 and the metal wiring board 4 are connected by conducting a heat treatment, and a metal wiring layer, having a fine and complicated pattern, is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramics wiring board in which a ceramics board and a metal wiring board are joined via a brazing material layer.

[0002]

2. Description of the Related Art Ceramics substrates have been put to practical use as substrates for mounting electronic components, particularly high-power and high-power semiconductor elements, because they have characteristics such as high electrical insulation, high thermal conductivity, and low thermal expansion. .. By the way, when a ceramic substrate is used as a substrate for mounting electronic components, it is essential to bond it to a metal for the purpose of forming an electric circuit.

As a method of joining the ceramic substrate and the metal wiring board when manufacturing the wiring board as described above, a so-called DBC method (direct bonding (Kappa method) and joining methods using active metals such as IVa group elements and Va group elements are known. The active metal method is T
It is a joining method that utilizes the fact that metal elements such as i, Zr, and Nb easily wet and react with the ceramic material.
Specifically, as a brazing method using a brazing filler metal added with an active metal, a method of heating and joining by interposing an active metal foil or powder between a ceramic material and a metal material (solid phase diffusion bonding), etc. It's being used. In general, eutectic brazing material of Cu and Ag (Ag: 72w
A method is often used in which an active metal such as Ti is added to (t%), the active metal is interposed between the ceramic substrate and the metal plate, and heat treatment is performed at an appropriate temperature to perform bonding.

By the way, the above-mentioned DBC method has an advantage that the manufacturing process can be shortened because the copper wiring board having a desired shape can be directly bonded onto the ceramic substrate, but the bonding quality of the entire bonding surface is kept stable. Difficult to do,
There is a problem that it is difficult to form a fine wiring pattern because unbonded portions are likely to remain. Therefore, a plate-shaped copper plate or the like is uniformly bonded on a ceramic substrate by an active metal method, and then the metal plate is subjected to etching treatment to form a fine wiring pattern.

[0005]

According to the method for manufacturing a ceramic wiring board that combines the active metal method and the etching treatment described above, a finer wiring pattern can be formed as compared with the DBC method, but a plate-like method is used. Since the metal plates are completely bonded and then patterned by etching, it is only possible to etch from one side and it is very difficult to linearly etch the side of the wiring part. Had a problem. That is,
Since sagging easily occurs on the side surface base of the wiring part, even if the wiring width is narrowed, the sag of the side surface base cannot reduce the distance between the lines, which causes a problem that the wiring density cannot be sufficiently increased. ing. As described above, in the method in which the active metal method and the etching treatment are combined, there is a limit to the line width and the line that can be substantially formed, and therefore, it is not sufficiently dealt with the diversified fine wiring pattern. That is the current situation.

Further, in the method in which the active metal method and the etching treatment are combined, the conductive substance is apt to remain in the portion of the surface of the ceramic substrate where the metal plate is removed by the etching treatment. Therefore, there is a problem that the manufacturing cost becomes high and a defect is likely to occur due to the conductive substance slightly remaining after the etching process. That is, in the case of the active metal method, a reaction product of the active metal component and the ceramic substrate, for example, an interface product such as TiN is generated at the bonding interface on the ceramic substrate side. On the other hand, in the copper plate etching removal step, an etching solution such as ferric chloride solution is usually used, but such an etching solution cannot dissolve and remove the interface product. Since the interface product containing the active metal generally has conductivity, it cannot be used as a wiring substrate if it remains on the ceramic substrate. Therefore, at present, using a special etching solution,
Interface products are removed by dissolution.

From the above, it is possible to accurately form a wiring pattern having a narrower line width and a space between lines, and to remove interface products remaining on the surface of the ceramic substrate due to the active metal method. It is required to reduce the man-hours required for.

The present invention has been made to address such a problem, and made it possible to form a metal wiring layer having a finer and more complicated pattern on a ceramic substrate with good reproducibility and at low cost. It is an object of the present invention to provide a method for manufacturing a ceramic wiring board.

[0009]

According to the method of manufacturing a ceramics wiring board of the present invention, a metal wiring layer having a desired wiring pattern is formed on the ceramics board to manufacture the ceramics wiring board. A step of forming a resist pattern on a portion excluding a portion where the wiring pattern is formed, and an active metal component is formed on the portion where the wiring pattern is formed on the ceramic substrate by the thin film forming method using the resist pattern as a shielding material. A step of forming a brazing material layer containing the same, a step of removing the resist film, a metal wiring board having the wiring pattern shape is laminated and arranged on the brazing material layer, and a heat treatment is applied to the ceramic substrate and the metal wiring. And a step of forming a metal wiring layer by joining with a plate.

[0010]

In the method for manufacturing a ceramic wiring board of the present invention, a brazing material layer corresponding to the wiring pattern is formed by using a resist pattern, and a metal wiring board patterned in advance by etching or the like is used. Therefore, a metal wiring layer having a complicated and fine wiring pattern can be formed with good reproducibility without causing sagging or the like on the side surface of the wiring portion. In addition, since the brazing material layer is made to correspond to the wiring pattern from the beginning, a conductive substance, that is, an interface product such as an active metal nitride is not generated on the surface of the ceramic substrate other than the wiring pattern formation site. Therefore, the process of removing it can be omitted,
It is possible to significantly reduce the manufacturing cost.

[0011]

EXAMPLES Next, examples of the present invention will be described.

FIG. 1 is a diagram sequentially showing a manufacturing process of a ceramic wiring board according to an embodiment of the present invention. First, a photoresist is applied to the surface of the ceramic substrate 1.
Then, the photoresist is exposed using a mask (not shown) corresponding to a desired wiring pattern. After that, the photoresist is developed to form a resist pattern 2 on a portion of the surface of the ceramic substrate 1 excluding a portion where a desired wiring pattern is formed, as shown in FIG.

As the ceramic substrate 1 to be used, various ceramic substrates can be applied, from oxide ceramic substrates such as aluminum oxide to non-oxide ceramic substrates such as aluminum nitride, silicon nitride and silicon carbide. Is. However, the present invention is particularly effective in the case of using a nitride-based ceramics substrate or the like in which a conductive interface product is easily formed at the bonding interface on the ceramics substrate side due to the active metal component in the brazing material described later. ..

Next, the resist pattern 2 is used to form a brazing material layer 3 containing an active metal component on the surface of the ceramic substrate 1 by a thin film forming method such as a sputtering method or an evaporation method, and then the resist pattern 2 is formed. By removing the, the active metal-containing brazing material layer 3 having a desired wiring pattern shape is formed as shown in FIG.

Here, as the brazing material layer 3, for example,
An active metal-containing brazing filler metal is mainly used which has an eutectic composition of Ag-Cu or a composition in the vicinity thereof, and an active metal component such as Ti, Zr, Hf, and Nb is added thereto in an appropriate amount. The addition amount of the active metal in the brazing material is, for example, about 1% by weight to 10% by weight.
The Ag-Cu alloy, which is the main brazing filler metal, basically satisfies the eutectic composition, but if the Cu content in all brazing filler metal components is approximately 15% to 35% by weight, the same applies. It is possible to obtain various effects. The main component of the brazing material is not limited to the above Ag-Cu eutectic brazing material, but various brazing materials such as Cu, Ag-Cu-Sn, Ag-Cu-In can be used. Is.

As the method of forming the active metal-containing brazing material layer 3, various thin film forming methods such as the sputtering method and the vapor deposition method can be used as described above. Further, as a thin film forming material such as a target in the sputtering method, each material may be used alone, or may be alloyed in advance with an active metal component included. The active metal-containing brazing material layer 3 preferably has a thickness of about 0.3 μm to 10 μm.

Thereafter, a metal wiring board 4 which is patterned in advance to have a desired wiring shape is aligned and laminated on the active metal-containing brazing material layer 3. The material of the metal wiring board 4 may be appropriately selected from various metal materials depending on the application, and for example, Cu, Cu alloy, Ni, Ni alloy, W, Mo or the like is used. Then, heat treatment is performed under the conditions (atmosphere, temperature, time, etc.) according to the active metal-containing brazing material 3 used, and the ceramic substrate 1 and the metal wiring board 4 are bonded together, as shown in FIG. Then, a ceramic wiring substrate 5 is obtained in which the metal wiring layer 4 having a desired wiring pattern is formed on the ceramic substrate 1. The joint is
For example, the heat treatment is performed at a temperature of about 800 ° C to 900 ° C for about 2 minutes to 10 minutes.

In the above-described embodiment, the brazing material layer 3 is formed by the thin film forming method while the brazing material layer 3 is patterned by the resist. Therefore, the brazing material layer 3 corresponding to a finer wiring pattern is formed only in a necessary portion. can do. Also,
Since the metal wiring board 4 used is previously patterned by etching or the like, a finer and more complicated shape can be accurately reproduced. That is, sagging or the like does not occur on the side surface of the wiring portion. Then, the metal wiring board 4 accurately reproducing such a fine wiring pattern is arranged on the brazing material layer 3 provided on the ceramic substrate 1 corresponding to the pattern shape, and the ceramic substrate 1 and the metal wiring board are arranged. Since they are heat-bonded to each other, it is possible to accurately form a metal wiring layer having a narrower line width and space. According to the method for manufacturing a ceramic wiring board of this embodiment, it is possible to stably reproduce a fine wiring pattern having a line width of 0.1 mm and a line spacing of about 0.15 mm.

Further, since the shapes of the brazing material layer 3 and the metal wiring board 4 are made to correspond to the desired wiring pattern from the beginning, a conductive substance, that is, an active material, on the surface of the ceramic substrate 1 other than the portion where the wiring pattern is formed is formed. No interface products such as metal nitrides are formed. Therefore, the step of removing the conductive material can be omitted, the manufacturing cost can be significantly reduced, and the insulation failure due to the residual conductive material is not caused.

Next, a specific example based on the above embodiment will be described.

Example First, a photoresist is uniformly applied to the surface of an 63 mm × 29 mm × 0.8 mmt aluminum nitride substrate, and then a wiring pattern to be formed (minimum line width = 0.1 mm, minimum line spacing = 0.15 mm). )
The photoresist was exposed using a mask according to.
Then, development was performed to form a resist pattern that covers only a portion other than the wiring pattern forming portion (FIG. 1A).

Next, the aluminum nitride substrate having the above resist pattern was set in a sputtering apparatus, and Ag, Cu and Ti were respectively placed as sputtering targets. Ar was introduced as a sputtering gas into the apparatus, and the inside of the apparatus was adjusted to 3 × 10 ⁻⁵ Torr. After that, DC power was supplied to each target, and ternary simultaneous sputtering was performed to form an Ag-Cu-Ti thin film (brazing material layer) on the aluminum nitride substrate. The composition of the Ag-Cu-Ti thin film was adjusted by adjusting the amount of power supplied to each target.
= 70.6: 27.4: 2.0 was adjusted. Then, after the formation of the brazing material layer was completed, the resist was dissolved and removed to form an active metal-containing brazing material layer having a desired wiring pattern shape (FIG. 1 (b)).

On the other hand, the above wiring pattern shape (minimum line width =
A copper wiring board (oxygen-free copper) having a pattern of 0.1 mm and a minimum distance between lines of 0.15 mm was prepared by etching. Then, this copper wiring board on the active metal-containing brazing material layer,
After arranging and stacking while aligning, heat treatment is performed in a vacuum of 1 × 10 ⁻⁴ Torr under conditions of 850 ° C. × 10 minutes to bond the aluminum nitride substrate and the copper wiring board, and to obtain the target. A ceramic wiring board was obtained (FIG. 1 (c)).

When the shape of the copper wiring layer of the ceramic wiring board thus obtained was visually observed, it was found that the minimum wiring width was 0.1 mm and the minimum wiring distance was 0.15 mm, as originally assumed, and was accurately formed.

[0025]

As described above, according to the method for manufacturing a ceramic wiring board of the present invention, a wiring pattern having a narrower line width and a narrower space can be accurately formed, and the active metal method is used. Due to this, the number of steps required to remove the interface product remaining on the surface of the ceramic substrate can be omitted. Therefore, the metal wiring layer having a fine and complicated pattern can be formed on the ceramic substrate with good reproducibility and at low cost.

[Brief description of drawings]

FIG. 1 is a perspective view sequentially showing a main part of a manufacturing process of a ceramics wiring board according to an embodiment of the present invention.

[Explanation of symbols]

 1 ... Ceramic substrate 2 ... Resist pattern 3 ... Active metal-containing brazing material layer 4 ... Metal wiring board 5 ... Ceramic wiring board

Claims (1)

[Claims] 1. When a metal wiring layer having a desired wiring pattern is formed on a ceramic substrate to manufacture a ceramic wiring substrate, a resist pattern is formed on a portion of the ceramic substrate excluding a portion where the wiring pattern is formed. And a step of forming a brazing material layer containing an active metal component by a thin film forming method using a resist pattern as a shielding material at a site where the wiring pattern is formed on the ceramic substrate, and the resist film is removed. And a step of stacking the wiring pattern-shaped metal wiring board on the brazing material layer and performing a heat treatment to bond the ceramic substrate and the metal wiring board to each other to form the metal wiring layer. A method for manufacturing a ceramics wiring board, comprising: