JPH01286494A - Ceramic substrate - Google Patents

Abstract

PURPOSE:To ensure desirable airtightness of a substrate without breaking ceramics by specifying a diameter of through holes and filling the through holes with Cu powder and/or Au powder. CONSTITUTION:A circuit conductor 14 is formed (into thin film patterns) by vapor deposition or by sputtering and etching while through holes are filled with Cu and/or Au. The through holes have a diameter of 0.25mm or less. The through holes with a diameter of 0.25mm or less does not break a ceramic substrate and provide desirable airtightness. Further, such through holes have sufficiently small resistance.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention forms a conductive wiring metal film on the surface of a substrate by vapor deposition or sputtering, and is applied to a ceramic multilayer film used in high-speed processing elements of the type equipped with silicon bare chips. This relates to improvement of the N substrate.

(Prior Art) (Problem to be Solved by the Invention) In recent years, the demand for miniaturization of semiconductor devices has become more severe, and various improvements have been made to ceramic multilayer substrates. The through hole diameter in the board is required to be as small as possible, for example φ0.08+
Although it is desired to realize a metallizing composition as small as u~φ0.25 m, a metallizing composition suitable for this has not yet been determined.

For example, when alumina is used as a ceramic substrate,
Mo metallization is used, but when the through hole diameter becomes small to about φO,OTom~φ0.0111,
The resistance value becomes too high, which poses a practical problem.

In addition, in low-temperature fired ceramic substrates, Cu or CuO
It is said that metallizing compositions based on C.
In the case of U-based products, Cu is oxidized during the degreasing process in the atmosphere, resulting in volumetric expansion, and in the case of CuO-based products, CuO becomes oxidized by reduction or heating in a neutral atmosphere.
When the metallization becomes a conductor, volumetric contraction occurs, and such expansion and contraction of the volume of the metallization may cause cracks in the ceramic substrate and wiring, and furthermore, the metallization composition in the through hole and the ceramic substrate may be damaged. The mismatch in the firing shrinkage rates of the two may result in four defects due to the creation of a gap between the inner wall of the through hole and the Cu, or the occurrence of a crank in the conductor part.

As shown in Japanese Patent Application No. 62-129441, this point has been improved by reducing the volume expansion and contraction changes due to oxidation and reduction of Cu or CuO using Pd/Cub/Cu and Pt/Cub/Co metallized compositions. Although some results were obtained, it was found that since Pd or pt was mixed in the metallizing composition, the electric resistance value was high and the through hole diameter was small, making it impossible to use it.

(Means for Solving the Problems) As a result of intensive studies to solve this problem, the present invention has been developed to provide a through-hole with a specific through-hole diameter of 0.25 mm even when using Cu alone or Au4i, which had been thought to be undesirable in the past.
Expansion below mm, preferably below 0.20 mm;
It has been found that the influence of shrinkage is small and that it is favorable for electrical conduction.

(Function) The details of the present invention will be explained one by one for each step with reference to the drawings. (See Figure 1 below) As shown in Japanese Patent Application Laid-Open No. 59-92943, Z
nO4χ, MgO13χ, A120323χ, 5i
Oz 5B! , 8203 and PzOs at 1% each.
Weigh SiO
After melting at 50℃, it is poured into water, rapidly cooled and vitrified, and then processed in an alumina ball mill to reduce the average particle size to 2μ to 3μ.
Grind to make frits. This frit is mixed with an organic binder and a solvent to form a slurry, and a green sheet with a thickness of 0.6 mm (which will become the substrate 11 after firing) is produced by a doctor blade method.

Next, a through hole 12 is formed by punching a hole at a predetermined position. Then, metallization 13 is embedded in this through hole 12. Preparation ingredients for metallization shall consist of 100 parts by weight of Cu powder, 8 parts by weight of resin, and an appropriate amount of solvent.

Next, after cutting the outer shape of the green sheet into a predetermined shape, the resin contained in the green sheet and the Cu paste is scattered.

The resulting product is calcined in the atmosphere at 600° C. to 750° C. to burn off and remove residual carbon.

Next, CuO in the through hole 12 is reduced to Cu at 350° C. to 750° C. in an atmosphere of N113 decomposed gas.

Next, firing is performed in an N113 decomposition gas atmosphere or a neutral atmosphere to sinter the ceramic and Cu.

The surface of the thus-obtained material is polished, and the Cu ejected on the substrate surface due to volumetric expansion due to Cu oxidation during the calcination process is polished away and scraped off, at the same time creating a smooth surface for subsequent vapor deposition and sputtering steps.

Next, a circuit conductor 14 was formed by vapor deposition or sputtering and etching (thin film pattern), and then the through hole was filled with Cu, Au (invention), and Pd/Cu0 (comparative example) in a test sample. Table 1 shows the relationship between the presence or absence of fracture in the ceramic, and Table 1 shows the results of measuring the inner diameter of this through hole and the resistance value of each metallization described above using a ceramic substrate with a thickness of 1.1 ms. Table 2 shows the results.

According to this, when the inner diameter of the through hole was φ0.25 mm or less, preferably φ0.20 mm or less, the ceramic did not break, the airtightness was good, and the resistance of the through hole was small and satisfactory.

Table 1 Cu grain size and ceramic fracture around through hole (a)
X: Fracture Airtightness is also passed except for the × mark 1 xto-
'Std/cc or less Table 2 Through-hole resistance (mΩ) (When using Cu powder with a particle size of 15μ or more, it is difficult to form a dense sintered body and the resistance of the through-hole becomes hard.

Commercially available paste may be used.

As a representative example, DuPont's 57180 was tested and similar results were obtained.

Although the above example shows a case in which circuit conductors are provided on both the upper and lower surfaces of a ceramic substrate, as shown in FIG. 2, a thick film metallized layer 13 of Cu or Au is formed as a circuit conductor inside the substrate. , or the case where the substrate itself is formed into multiple layers as shown in FIG. (In FIGS. 2, 3, and 3, the same parts as in FIG. 1 are given the same reference numerals, so explanations are omitted.) (Effects of the Invention) According to the present invention, the diameter of the through-hole of the ceramic 54 is φ0. Even if it is less than 25 m1, the conductor resistance is small and the airtightness of the substrate can be ensured without causing ceramic breakage even though Cu or Au alone is used for metallization.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views of each embodiment of the present invention. 11... Board, 12... Through hole, 13...
Thick film metallization, 14...Circuit conductor

Claims (1)

[Claims] In a ceramic substrate in which conductor wiring of a ceramic substrate having two or more conductor wirings is electrically connected by metal filled in the through-hole hole, the through-hole hole has a hole diameter of 0.
．． A ceramic substrate having a thickness of 25 mm or less and filled with one or more of Cu powder and Au powder.