JP2690631B2 - Manufacturing method of ceramic wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a ceramic wiring board used for a hybrid integrated circuit device, a package for housing a semiconductor element, and the like.

[0002]

2. Description of the Related Art Conventionally, a ceramic wiring board used for a hybrid integrated circuit device, a package for housing a semiconductor element, or the like is usually Mo-Mn on the surface or inside of a plate-shaped sintered ceramic body having external lead pins attached to the lower surface. A circuit wiring is formed by a thick film forming technique such as a method, and a part of the circuit wiring is led out to an external lead pin attached to the lower surface of the plate-shaped sintered ceramic body so as to have electrical conduction. doing.

In the Mo-Mn method, a metal powder made of a refractory metal such as tungsten (W), molybdenum (Mo), manganese (Mn), etc., is added with an organic solvent and a binder to form a paste-like metal. The paste is printed and applied on the outer surface of the green or sintered ceramic body by screen printing in a predetermined pattern as circuit wiring, and then this is fired in a reducing atmosphere to sinter and integrate the refractory metal and the ceramic body. Is the way.

However, when circuit wiring is formed by using the Mo-Mn method, since the circuit wiring is formed by screen printing of a metal paste, the line width of the wiring becomes 100 μm or more, and the wiring becomes finer. However, it is difficult to increase the density of circuit wiring.

In order to solve the above-mentioned drawbacks, ceramic wiring boards formed by using a thin film forming technique capable of miniaturization instead of forming circuit wiring by a conventional thick film forming technique have been used. Was.

The ceramic wiring board formed by forming the circuit wiring by a thin film forming technique is usually provided on the outer surface of a plate-shaped sintered ceramic body whose surface is flattened by mechanical polishing, for example, by an ion plating method or a sputtering method. An adhesive layer made of titanium (Ti) or chromium (Cr) and a barrier layer made of silver (Ag), nickel (Ni), palladium (Pb), etc. are sequentially deposited, and then these layers are etched. And a copper (Cu) layer as a main conductor layer is formed on the barrier layer by plating.

[0007]

However, a ceramic wiring board on which circuit wiring is formed by using the thin film forming technique usually has a plate-shaped sintered body in order to form the circuit wiring on the surface of the plate-shaped sintered ceramic body with high dimensional accuracy. If the surface of the ceramic body is mechanically polished with a lapping machine or a plane grinding plate to make the surface flat, and if the surface of the plate-like sintered ceramic body is mechanically polished with a lapping machine, etc. Since the sintered ceramic body has a large number of pores in its crystal structure, the corners of the entrance are angular, and a large number of recesses are formed on the surface with a narrow entrance and widening inside. When a circuit wiring composed of a fine pattern with a line width of about 50 μm is formed on the sintered ceramic surface by a thin film forming technique, a part of the circuit wiring is cut by the concave portion and may be disconnected. Electric resistance of the part cavity formed circuit wiring in the circuit wiring has a disadvantage in that deviate significantly from a predetermined value.

Further, the ceramic wiring substrate is made by mechanically polishing the surface of the plate-shaped sintered ceramic body to make it flat,
When dust and debris adhering to the surface are washed with water, water penetrates into the concave portion having a narrow entrance of the surface of the plate-shaped sintered ceramic body and spreads inside, and remains, and this is layered on the surface of the plate-shaped sintered ceramic body. There is also a drawback that the circuit wiring is oxidized and corroded by contact with the circuit wiring to be formed, causing a variation in the electric resistance value of the circuit wiring and breaking the circuit wiring.

In order to solve the above-mentioned disadvantage, the plate-shaped sintered ceramic body whose surface is mechanically polished is fired again, and the glass component contained in the sintered ceramic body is put on the surface of the plate-shaped sintered ceramic body. It is conceivable to make the surface smooth by depositing and filling the concave portions on the surface with a glass component.

[0010] However, the plate-shaped sintered ceramic body whose surface is mechanically polished has an internal stress due to the mechanical polishing on its surface, and when the plate-shaped sintered ceramic body is fired again, the internal stress is applied. Warpage of about 15 to 50 μm occurs in the plate-shaped sintered ceramic body, and as a result,
This causes a disadvantage that it is impossible to form circuit wiring with high dimensional accuracy on the surface of the plate-shaped sintered ceramic body by the thin film forming technique.

[0011]

According to the method of manufacturing a ceramic wiring board of the present invention, a circuit wiring formed by a thin film forming technique is applied to the upper surface of a plate-shaped sintered ceramic body, and a plurality of external lead pins are provided on the lower surface. A ceramic wiring board that is attached, wherein the plate-shaped sintered ceramic body is formed by recessing the attachment position of the external lead pin inward from the lower surface of the plate-shaped sintered ceramic body and mechanically forming both upper and lower surfaces. It is characterized in that it is formed by polishing and then re-baking.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (a) to 1 (d) are cross-sectional views showing steps of a method for manufacturing a ceramic wiring board according to an embodiment of the present invention.
Is a plate-shaped sintered ceramic body, and 2 is a circuit wiring.

First, as shown in FIG. 1A, a plate-shaped sintered ceramic body 1 is prepared. The plate-shaped sintered ceramic body 1 is made of alumina ceramic or the like, for example, alumina (Al ₂ O
₃ ), silica (SiO ₂ ), magnesia (MgO), calcia
A suitable organic solvent or raw material powder such as (CaO) is added and mixed to form a slurry and a doctor blade method is used to form a ceramic green sheet (ceramic green sheet). The ceramic green sheet is formed by punching it into an appropriate shape, stacking multiple sheets, and firing at a high temperature (about 1600 ° C).

Incidentally, the plate-shaped sintered ceramic body 1 has an upper and lower height of 10 due to variations in the packing density of the raw material powder such as alumina.
It is warped by about 25 μm.

Further, the plate-shaped sintered ceramic body 1 is provided with a recess A on the lower surface thereof where the external lead pin is attached, and the entire surface of the bottom surface of the recess A is covered with the recess A. A metallized wiring layer 3 is formed over the upper surface.

The depression A provided on the lower surface of the plate-shaped sintered ceramic body 1 is provided, for example, when a plurality of ceramic green sheets are laminated to obtain a plate-shaped sintered ceramic body, a hole is formed in the lowermost ceramic green sheet. The metallized wiring layer 3 is formed by pre-baking a metal paste obtained by adding and mixing a suitable organic solvent or solvent to a refractory metal powder such as tungsten (W) or molybdenum (Mo). By filling a through-hole formed in advance in the ceramic green sheet that will be the bonded ceramic body 1, it is deposited and formed from the upper surface of the plate-shaped sintered ceramic body 1 to the entire bottom surface of the recess A 1.

Next, the upper and lower surfaces of the plate-shaped sintered ceramic body 1 are mechanically polished, and the upper and lower surfaces of the plate-shaped sintered ceramic body 1 are flattened as shown in FIG. 1 (b).

The mechanical polishing is performed by, for example, a lapping machine or a surface grinding plate, and the surface of the plate-shaped sintered ceramic body 1 is warped by about 10 to 25 μm, but the warp is flat by 5 μm or less. Make something.

When the upper and lower surfaces of the plate-shaped sintered ceramic body 1 are mechanically polished, the plate-shaped sintered ceramic body 1
Since the metallized wiring layer 3 extending to the lower surface side of the metallized wiring layer 3 is slightly inward from the lower surface of the plate-shaped sintered ceramic body 1 due to the depression A, the metallized wiring layer 3 is not polished and removed at all, and the external lead pins are firmly fixed. It has a predetermined area required for attachment.

Further, since the plate-shaped sintered ceramic body 1 has a large amount of pores in its crystal structure, the corners of the inlet are angular, and the recess B having a narrow inlet and a widening inside is formed on the surface in a large amount. It has been formed. Next, the plate-shaped sintered ceramic body 1 whose upper and lower surfaces are mechanically polished is re-fired, and the plate-shaped sintered ceramic body 1 is placed in the recess B formed on the surface of the plate-shaped sintered ceramic body 1. As shown in Fig. 1 (c), the plate-shaped sintered ceramic body 1 was prepared by precipitating the glass component contained therein and filling the recess B on the surface with the glass component.
Both upper and lower surfaces of the are flat and smooth.

Rebaking of the plate-shaped sintered ceramic body 1 is performed by putting the plate-shaped sintered ceramic body 1 in a furnace at a temperature of about 1050 to 1560 ° C. for about 20 hours.

When the plate-shaped sintered ceramic body 1 whose both upper and lower surfaces are mechanically polished is re-fired, the plate-shaped sintered ceramic body 1 has internal stress in the mechanically polished portion thereof and has a plate shape. The warped ceramic body 1 is warped, but the surfaces subjected to mechanical polishing are the upper and lower surfaces facing each other of the plate-shaped sintered ceramic body 1. It is possible to maintain the flatness of the sintered ceramic body 1 at about 5 μm.

The upper and lower surfaces of the plate-shaped sintered ceramic body 1 are flattened by mechanical polishing, and the upper and lower surfaces are smoothed by re-firing. Therefore, the upper surface of the plate-shaped sintered ceramic body 1 will be described later. When the circuit wiring 2 is layered by the thin film forming technique, a part of the circuit wiring 2 is cut by the recess B formed on the surface of the plate-shaped sintered ceramic body 1 to break the wire, or a part of the circuit wiring 2 is cut. There is no possibility that a cavity will be formed in the circuit wiring and the electric resistance of the circuit wiring 2 will deviate significantly from the specified value.
2 can be layered with a uniform thickness and a predetermined electric resistance value and a predetermined pattern with high dimensional accuracy.

Next, the plate-shaped sintered ceramic body 1 is shown in FIG.
External lead pins 4 are attached to the lower surface of the metallized wiring layer 3 by brazing it through a brazing material such as silver brazing, and the circuit wiring 2 is formed on the upper surface by a thin film forming technique such as vapor deposition or sputtering. Is applied to form a layered structure, which results in a ceramic wiring board as a product.

The external lead pins 4 are attached to the metallized wiring layer 3 even if the metallized wiring layer 3 mechanically polishes the upper and lower surfaces of the plate-shaped sintered ceramic body 1. Since the metallized wiring layer 3 and the external lead pins 4 have a large area on the bottom surface of the metallized wiring layer, the brazed area of the metalized wiring layer 3 and the external lead pins 4 can be made large. It becomes possible to wear.

The circuit wiring 2 formed on the upper surface of the plate-shaped sintered ceramic body 1 has a three-layer structure of an adhesive layer 5, a barrier layer 6 and a main conductor layer 7. Titanium as the adhesive layer 5, titanium-tungsten alloy as the barrier layer 6 and copper as the main conductor layer 7 were deposited to a predetermined thickness on the upper surface of the body 1 by a thin film forming technique such as vapor deposition or sputtering, and the adhesive layer was formed. 5, barrier layer
Each layer of 6 and the main conductor layer 7 is applied to the upper surface of the plate-shaped sintered ceramic body 1 in a predetermined pattern by etching the layers in a predetermined pattern using a photolithography technique.

Since the circuit wiring 2 is formed by a thin film forming technique, a line width 50 is formed on the upper surface of the plate-shaped sintered ceramic body 1.
μm, and as a result, many circuit wirings 2
Can be formed at high density.

The adhesive layer 5 constituting the circuit wiring 2 has the function of increasing the bonding strength between the sintered plate ceramic body 1 and the circuit wiring 2, and if the thickness is less than 0.01 μm, the circuit wiring 2 It becomes difficult to firmly bond the plate-shaped sintered ceramic body 1 to the plate-shaped sintered ceramic body 1, and if the thickness exceeds 1.0 μm, the plate-shaped sintered ceramic body 1 and the adhesive layer 5 are adhered to each other due to internal stress when the adhesive layer 5 is laminated by the thin film forming technique. The joint strength with 5 tends to decrease. Therefore, the adhesive layer 5 has a thickness of 0.01 to 1.0.
It is good to set it in the range of μm, preferably in the range of 0.03 to 0.5 μm.

A barrier layer 6 is layered on the upper surface of the adhesive layer 5, and the barrier layer 6 includes the adhesive layer 5 and the main conductor layer 7.
To prevent mutual diffusion with the adhesive layer 5 and the main conductor layer 7
And has the effect of firmly joining

If the thickness of the barrier layer 6 is less than 0.1 μm, it tends to be impossible to effectively prevent the mutual diffusion of the adhesive layer 5 and the main conductor layer 7, and if the thickness exceeds 5.0 μm, the barrier layer 6 The bonding strength between the adhesive layer 5 and the barrier layer 6 tends to decrease due to internal stress when the layers are laminated by the thin film forming technique. Therefore, the barrier layer 6 has a thickness of 0.
It is good to set it in the range of 1 to 5.0 μm, preferably 0.5 to 3.0 μm.

When the titanium-tungsten alloy constituting the barrier layer 6 has a titanium content of 0.2% by weight, the bonding strength between the adhesive layer 5 and the barrier layer 7 decreases, and
If it exceeds 30.0% by weight, the layer hardness of the barrier layer 6 increases, and it becomes difficult to relax the internal stress of the main conductor layer 7 formed thereon, and the bonding strength between the barrier layer 6 and the main conductor layer 7 decreases. There is a tendency. Therefore, the titanium content in the barrier layer 6 is preferably 0.2 to 30.0% by weight, particularly 3.0 to 20.0% by weight.

Further, the main conductor layer 7 is formed on the upper surface of the barrier layer 6.
Are laminated, and the main conductor layer 7 mainly functions as a passage for conducting electricity.

For the main conductor layer 7, for example, copper (Cu) having an extremely low conduction resistance is used, and if the thickness is less than 0.1 μm, the conduction resistance of the circuit wiring 2 becomes high and it is unsuitable as a ceramic wiring board. 0.1 μm
It is preferable that the above is taken into consideration.
To 15.0 μm, preferably 0.5 to 10.0 μm.

The present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the gist of the present invention. For example, nickel (Ni) or nickel (Ni) on the surface of the circuit wiring 2 can be used. By depositing a metal with good corrosion resistance such as gold (Au) and good conductivity to a thickness of about 2 μm, it is possible to effectively prevent the circuit wiring 2 from being corroded by moisture contained in the atmosphere. The electric resistance value of the circuit wiring 2 can always be made constant.

[0035]

According to the method for manufacturing a ceramic wiring board of the present invention, the plate-shaped sintered ceramic body is re-fired after mechanically polishing the opposite surfaces of the plate-shaped sintered ceramic body. The main surface of the sintered ceramic body facing each other is flat and smooth, and as a result, when the circuit wiring is layered on one main surface of the plate-shaped sintered ceramic body by a thin film forming technique, the circuit wiring is It is possible to form an extremely fine pattern having a uniform layer thickness and a predetermined electric resistance value and good dimensional accuracy.

Further, since the circuit wiring is formed by the thin film forming technique, the circuit wiring can be formed at a high density, and a large number of circuit wiring can be formed on a small plate-shaped sintered ceramic body.

Further, even if the opposite surfaces of the plate-shaped sintered ceramic body are mechanically polished, the metallized wiring layer formed in the plate-shaped sintered ceramic body on the lower surface of the plate-shaped sintered ceramic body is derived in a large area. As a result, it becomes possible to attach the external lead pins to the metallized wiring layer very firmly with a large brazing area.

[0038]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of each process for describing a method for manufacturing a ceramic wiring board of the present invention.

[Explanation of symbols]

 1 ... Plate-shaped sintered ceramic body 2 ... Circuit wiring 3 ... Metallized wiring layer 4 ... External lead pin 5 ... Adhesive layer 6 ... Barrier layer 7 ... Main conductor layer

Claims (1)

(57) [Claims] 1. A ceramic wiring board comprising a plate-shaped sintered ceramic body having an upper surface to which circuit wiring formed by a thin film forming technique is attached, and a lower surface to which a plurality of external lead pins are attached. The ceramic sintered body is formed by denting the attachment position of the external lead pin inward from the lower surface of the plate sintered ceramic body, mechanically polishing both upper and lower surfaces, and then re-baking. A method of manufacturing a ceramic wiring board, comprising: