JPH05304156A - Semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To provide a semiconductor integrated circuit for flip-chip having electrode parts durable against a plurality of times of mounting and does not collapse even if the electrode part is pressed by some extent from the rear at the time of bonding and in which nondestructive measurement of electrical characteristics can be made after formation of electrode. CONSTITUTION:Electrode part of the semiconductor integrated circuit has a structure wherein aluminum pads 2, a barrier metal 1a, and the like are formed on a semiconductor substrate 1 and the barrier metal layer 4 is applied with a metal core 6 having outer periphery thinly coated with a solder layer 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor integrated circuit for flip chips, for example, for the purpose of integrated mounting of electric circuits at high density.

[0002]

2. Description of the Related Art In a conventional flip-chip semiconductor integrated circuit, most of its electrodes are composed of solder. For example, as shown in FIG. 5, a barrier metal layer 44 is formed on an aluminum pad 42 formed on a semiconductor substrate 41 through a contact hole of a protective film 43, and a solder bump 45 for bonding is formed on the barrier metal layer 44. And constitutes a solder electrode.

[0003]

With the above structure, when mounting the semiconductor integrated circuit on the substrate, heating it to melt the solder, and electrically connecting it to the electrodes on the substrate side, the weight alone is sufficient. Since there is a case where they are not joined, joining is performed by applying a certain force from the back surface of the substrate of the integrated circuit in addition to the dead weight. When the electrode itself is composed of solder, there is a problem that the solder itself is crushed by the force from the back surface and there is a risk of short-circuiting with an adjacent solder electrode. As shown in FIG. 6 (A),
When attempting joining by heating under pressure for more reliable joining, there is a disadvantage that the solder bump 45 itself is crushed as shown in FIG. 6B, and adjacent solder electrodes are short-circuited. Pressure operation is difficult.

Further, even if the semiconductor integrated circuit once mounted on the substrate is peeled off by heating again, the amount of solder left on the substrate side and the semiconductor integrated circuit side is uneven, and it is difficult to mount it again on the substrate. There is a problem that is. That is, as shown in FIG. 7, in the conventional solder electrode, when a defect occurs in the IC chip or the wiring board, the wiring board 47 is heated and the semiconductor substrate 41 is removed by the removal tool 50.
It is difficult to control the amount of solder left on the side of the semiconductor substrate 41 and the amount of solder left on the wiring substrate 47 side. Is difficult.

Further, the solder is soft even at room temperature, and when the plated solder is once heat-treated at a temperature higher than the melting point, the solder is deformed into a spherical shape. Therefore, when evaluating the electrical characteristics of the semiconductor integrated circuit, There is a problem that the needle may damage the solder, or the needle of the probe may not surely contact all the electrodes of the semiconductor integrated circuit.
That is, as shown in FIG. 8, in the conventional solder electrode, since the entire electrode is formed of solder, for example, when probing with a thin metal needle 52 at the time of operation inspection, the metal needle 52 easily digs into the solder bump 45 and the solder bump 4
There are inconveniences that the shape of No. 5 is remarkably changed and the electrode itself is peeled off.

The present invention has an electrode structure capable of withstanding multiple times of mounting, non-destructive measurement of electrical characteristics after electrode formation, and not crushed to a certain degree or more even when pressure is applied from the back surface at the time of bonding. A semiconductor integrated circuit is provided.

[0007]

In order to achieve the above object, the present invention forms a core of a high melting point metal inside an electrode directly attached to a semiconductor integrated circuit, and covers the outer periphery of the core with a low melting point metal. It is characterized by having a structure.

[0008]

[Function] A high melting point metal core is formed inside an electrode directly attached to a semiconductor integrated circuit, and its outer periphery is covered with a thin low melting point metal.
The adjacent solder electrodes are not short-circuited with each other, the joint portion can be reused, and the electrodes themselves are not peeled off during the operation inspection.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a structural sectional view of an electrode portion of a semiconductor integrated circuit according to an embodiment of the present invention. The semiconductor integrated circuit according to the present invention has a large number of electrode portions as shown in FIG. 1, and the electrode portions are formed on the aluminum pad 2 formed on the semiconductor substrate 1 through the contact holes of the protective film 3. The barrier metal layer 4 is formed, and the inside of the barrier metal layer 4 is occupied by a metal core 6 which is a high melting point metal such as copper, and the solder layer 7 which is a low melting point metal is the metal core 6 thereof. It has a structure having a thinly coated outer periphery.

The metal core 6 may be a refractory metal having conductivity and nickel or the like may be used. In addition, indium, indium-gallium, tin, and the like can be considered as the low-melting-point metal that thinly coats the outer periphery of the metal core 6.

FIG. 2 is a cross-sectional view of a state in which an electrode portion of a semiconductor integrated circuit and another wiring substrate according to an embodiment of the present invention are joined together by heating under pressure. According to the present invention, since the metal core 6 made of copper or the like is formed inside the electrode, when pressure heating connection is attempted, only the solder layer 7 on the surface is crushed and melted and connected to the wiring board. The metal core 6 is not crushed and is kept in contact with the electrode 10 of the wiring board. Therefore, the electrodes can be bonded to each other with a high probability without short-circuiting the solder of the adjacent electrodes.

FIG. 3 is a schematic diagram of the repairability of the junction portion of the semiconductor integrated circuit in one embodiment of the present invention. According to the present invention, the solder 8 that melts during heating exists only on the outer circumference of the metal core 6, and the absolute amount is significantly smaller than that of the conventional one. The amount of solder left on each of the electrodes 10 on the substrate is almost the same for all electrodes, and the electrodes can be mounted again and reused.

FIG. 4 is a schematic view showing the state of the operation inspection of the semiconductor integrated circuit in the embodiment of the present invention. Since the electrode portion of the semiconductor integrated circuit according to the present invention has the metal core 6 therein, the probe cannot be penetrated into the metal core 6 by probing with the metal needle 12 at the time of operation inspection, and the physical surface of the electrode is not physically penetrated. Can significantly reduce damage.

[0015]

According to the present invention, in order to connect the electrode and the metal pad on the substrate side with high probability, even if a certain force is applied from the back surface of the semiconductor integrated circuit at the time of heating, the high melting point forming the core It is possible to avoid problems such as short-circuiting between electrodes by forming a pillar without crushing the metal.

Further, the flip-chip semiconductor integrated circuit mounted once can be mounted on another substrate and used again for convenience of assembly.

Further, since the metal core having a higher melting point than that of solder is provided inside, probing can be performed with little damage even after the solder electrode is formed, and the electrical characteristics of the semiconductor integrated circuit can be evaluated.

[Brief description of drawings]

FIG. 1 is a structural cross-sectional view of an electrode portion of a semiconductor integrated circuit according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a state in which the electrode portion of the semiconductor integrated circuit and the wiring board according to one embodiment of the present invention are joined by heating under pressure

FIG. 3 is a schematic diagram of repairability of a junction portion of a semiconductor integrated circuit according to an embodiment of the present invention.

FIG. 4 is a schematic diagram of a state of operation inspection of a semiconductor integrated circuit in an embodiment of the present invention.

FIG. 5 is a structural sectional view of an electrode portion of a conventional semiconductor integrated circuit.

FIG. 6 is a sectional view showing a state in which a conventional semiconductor integrated circuit electrode portion and a wiring board are joined together by heating under pressure.

FIG. 7 is a schematic diagram of repairability of a junction portion of a conventional semiconductor integrated circuit.

FIG. 8 is a schematic diagram of a conventional semiconductor integrated circuit operation inspection state.

Claims (1)

[Claims] 1. In one having a large number of solder bump electrodes on its circuit and joined to another substrate via this bump, the inside of this bump is formed of a high melting point metal,
A semiconductor integrated circuit having an electrode structure having an outer periphery covered with a film of a low melting point metal.