JPS6295838A - Connection structure for ceramic substrate - Google Patents

Abstract

PURPOSE:To remove the gas in a low-melting point metal effectively and selectively by forming the configuration of a part of a low-melting point connection part of the side of a ceramic substrate so as not to be able to develop affinity with the low-melting point metal. CONSTITUTION:A part capable of developing affinity with a low-melting point metal 4 in the center and its vicinity of a conductor 8 to be connected to the metal 4 and a part uncapable of affiliating with the metal 4 lacking part of the part are formed in the conductor 8. When gas is generated in the metal 4 at high temperature, the gas shifts in the 4 due to a difference in specific gravity. When the gas shifts to the side of a ceramic substrate 6, the gas heads toward a part in a large height direction. As that part is ready-formed in a structure wherein the part does not develop affinity with the metal 4, the gas comes into contact with a part in a metal 4-free state. The gas is extruded by the surface tension of the metal 4. Hereby, the gas in the metal 4 is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a face-down integrated circuit device, and relates to a method of constructing a low melting point metal connection portion of a ceramic substrate to a load.

[Background of the invention]

FIG. 7 is a sectional view of a conventionally known face-down connection type integrated heating device, and FIG. 8 is a plan view of the ceramic substrate side with the low melting point metal removed. A through hole is provided in the upper insulating film 3 of the intra-chip wiring conductor 2 of the semiconductor chip 1, a conductor 5 which is compatible with the low-temperature metal 4 is formed, and a ceramic substrate 6 is formed.
An insulating layer 7 is formed on the wiring conductor 9 in the substrate, and the low melting point metal and the conductor 8 to be connected are connected to each other through the low melting point metal. Generally, when gas is generated in the low melting point metal or is already taken in, the gas moves through the groove bottom due to the difference in specific gravity between the low melting point metal and the low melting point metal at high temperatures. When the side on which the gas moves is the ceramic substrate side, the gas existing near the center when viewed from the plane of FIG. 8 moves due to the difference in specific gravity until it reaches near the center of FIG. 2 and is fixed. If the volume of gas in the low melting point metal is large, the ideal connection area shown in Figure 8 will become an insulator and the gas will significantly reduce the area, resulting in a cataclysmic situation 1 or compromise. The result is a decrease in confidence.

This type of @fermentation is related to, for example, JP-A-53-37583.

[Purpose of the invention]

It is an object of the present invention to provide for the removal of gases having a large volume fIt from among the gases generated or already incorporated into the low melting point metal by means of a planar structure of a conductor that is compatible with the low melting point metal.

[Summary of the invention]

The feature of the present invention is to take into account that when a semiconductor chip is mounted on a ceramic substrate, gas in the low-melting point metal may cause an unconnected or almost unconnected state. The reason is that the shape of the connecting portion provided for compatibility is partially removed to form a portion that is not compatible with the low melting point metal.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 to 4.

FIG. 1 shows a cross-sectional view of a semiconductor chip, a ceramic substrate, and a low melting point metal in a face-down connected portion. Second
The figure is a plan view of the connection portion on the ceramic substrate side excluding the low melting point metal.

1 is a semiconductor chip, 2 is an in-chip wiring conductor, 3 is an insulating film, 4 is a low melting point metal, and 5 is a conductor that makes the in-chip wiring conductor compatible with the low melting point metal. 6 is a ceramic substrate, 7 is an insulating layer of the ceramic substrate, and 8 is a conductor to be connected to a low melting point metal, at least near the center of the part that can be compatible with the low melting point metal, and a further part is missing and the low melting point is removed. It forms a part that is incompatible with metal. 9 is a wiring conductor within the board. 10 is a gas present in the low melting point metal.

The connection part of the ceramic board is -N above the wiring conductor in the board.
An insulating film is formed on the insulating film, and a conductor that is compatible with the low melting point metal is formed on the wiring conductor in the substrate without the insulating film. It is assumed that the low melting point metal is formed on the semiconductor chip side. The semiconductor chip is positioned on and in contact with the ceramic substrate, and passed through a high temperature furnace to melt and connect the low melting point metal between the semiconductor chip connection portion and the ceramic substrate connection. At this high temperature, when gas is generated in the low melting point metal, or if some gas is already trapped in the low melting point metal, the gas expands and becomes large in volume as the temperature rises, as shown in Figure 6. Displaces inside melting point metals depending on the difference in specific gravity.

When the gas moves toward the ceramic substrate side, it moves towards the larger part in the height direction in FIG. Since that part has a structure that is not compatible with low melting point metals, the gas comes into contact with the part in a state where there is no low melting point metal.

This part does not have an affinity with the low melting point metal, so it cannot be in a stable position, and the gas is forced out due to the surface tension of the low melting point metal. This allows the gas in the low melting point metal to be removed.

At high temperatures, the low melting point metal is in a liquid or near-liquid state, and small-scale gases that cannot be moved by the expanded gas in the low melting point metal do not increase the connection resistance and do not need to be removed.

] A gas that can thermally expand and move through a low melting point metal due to the difference in specific gravity will greatly reduce the width of the ideal connection surface and will likely increase the connection resistance between the semiconductor chip and the ceramic substrate. Gases can be efficiently and selectively removed.

FIG. 3 is a cross-sectional view of a semiconductor chip, a ceramic substrate, and a low melting point metal, similar to FIG. 1. FIG. 4 is a plan view of the ceramic substrate side with the low melting point metal removed in the same way as FIG. 2.

In FIGS. 3 and 4, the shape of the portion of the ceramic substrate that is not compatible with the low melting point metal is formed to be similar to that of the wiring conductor within the substrate. This makes it possible to remove the gas in the low melting point metal, and at the same time, it can be directly applied to the S-conductor which forms a conductor that is compatible with the low melting point metal through plating.

FIG. 5 is a cross-sectional view of a semiconductor chip, a ceramic substrate, and a low melting point metal, similar to FIG. 1. FIG. 6 is a plan view of the ceramic substrate side with the low melting point metal removed, similar to FIG. 2.

In FIGS. 5 and 6, the shape of the portion of the ceramic substrate l111 that is not compatible with the low melting point metal is formed using an insulating layer.

This makes it possible to remove gas from low-melting point metals, and at the same time, it can also be applied to the formation of conductors that are compatible with low-melting point metals through plating.

〔Effect of the invention〕

- As explained above, according to the present invention, the shape of a part of the low-melting point connection part on the ceramic substrate side is formed so that it is not compatible with the low-melting point metal, so that the gas in the low-melting point metal is not compatible with the low-melting point metal. It becomes possible to effectively and selectively remove it, and it becomes possible to reduce connection resistance and prevent a decrease in connection reliability.

[Brief explanation of drawings]

1, 3, and 5 are cross-sectional views of a face-down connection type integrated circuit according to an embodiment of the present invention, and FIGS. 21, 4, and 6 are sectional views of a low melting point metal on the substrate side according to the present invention. The plan view of the connection diagram, FIGS. 7 and 8, are a sectional view of a conventional face-down connection type integrated circuit and a plan view of a low melting point metal connection portion on the substrate side. 3... Insulating film, 4... Low melting point metal, 6... Ceramic substrate, 7... Insulating layer, 9... In-board wiring conductor.

Claims (1)

[Claims] 1. In a ceramic substrate with a low melting point metal connection part provided on a semiconductor chip and a chip connection part for face-down connection, the shape of a part of the low melting point metal connection part on the ceramic substrate side is made so that it is not compatible with the low melting point metal. A ceramic substrate connection structure characterized in that a low melting point metal connection part is formed by forming a ceramic substrate connection structure.