JP2633745C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode structure for mounting a semiconductor device on a circuit board, and more particularly to an electrode for a semiconductor device which is mounted face down. And the implementation. 2. Description of the Related Art Conventionally, soldering has often been used for mounting a semiconductor device on a circuit board. However, recently, due to the miniaturization of the package of the semiconductor device and the increase in the number of connection terminals, the number of connection terminals has been increased. The spacing has become narrower and increasingly difficult to address with conventional soldering techniques. Therefore, recently, a method has been devised in which a bare semiconductor device is directly mounted on a circuit board to reduce the mounting area and efficiently use the semiconductor device. Above all, when connecting a semiconductor device to a circuit board, an electrode structure composed of a vapor deposited film of an adhesion metal or a diffusion preventing metal on an aluminum electrode pad of the semiconductor device in advance and a solder layer formed thereon by plating is used. The mounting structure in which the semiconductor device is turned downward (face down) and heated to a high temperature to fuse the solder to the terminal electrodes of the circuit board,
It is considered to be an effective method because the mechanical strength after connection is strong and the connection can be made collectively. (For example, Industrial Research Council, published on January 15, 1980, edited by Japan Microelectronics Association, "IC mounting technology") An example of the above-described electrode structure and mounting structure of the conventional semiconductor device will be described with reference to the drawings. explain. FIG. 3 is a schematic explanatory view of an electrode structure of a semiconductor device having a conventional solder bump electrode, and FIG. 4 is a schematic explanatory view of a mounting structure of the semiconductor device. In FIG. 3, reference numeral 8 denotes an IC substrate of a semiconductor device, and reference numeral 9 denotes an aluminum electrode pad. Reference numeral 10 denotes an adhesion metal film, and reference numeral 11 denotes a diffusion prevention metal film. Reference numeral 12 denotes a solder protrusion, and reference numeral 13 denotes a passivation film. In FIG. 4, 14 is a circuit board, and 15 is a terminal electrode. An outline of an electrode structure and a mounting structure of a conventional semiconductor device having a solder bump electrode configured as described above will be described below. First, an adhesion metal film 10 such as Cu and a diffusion prevention metal film 11 such as Cr are formed on an aluminum electrode pad 9 of an IC substrate 8 of a semiconductor device by vapor deposition. Thereafter, the portions other than the electrode portions are covered with a photoresist, and solder is deposited on the diffusion preventing metal film 11 by a plating method and solder reflow is performed to form solder protrusions 12 (FIG. 3).
Is obtained. Further, after the semiconductor device having the solder bump electrodes obtained as described above is positioned at a predetermined position on the circuit board 14 and mounted face-down,
The semiconductor device is mounted by heating to a high temperature of about 300 ° C. to melt the solder protrusions 12 and fuse them to the terminal electrodes 15. However, in the electrode structure and the mounting structure of the semiconductor device having the solder bump electrodes as described above, the following are required. The adhesion metal film and the diffusion prevention metal film are required on the aluminum electrode pad of the semiconductor device, which complicates the electrode structure and lacks versatility. [0011] 2. When heating to a high temperature to melt the solder and connect it to the terminal electrodes, it is not possible to maintain the gap between the IC substrate and the circuit board. And so on. [0012] The present invention has been made in view of the above problems, and has as its object
An object of the present invention is to provide an electrode structure and a mounting structure of a semiconductor device which can easily and reliably connect the semiconductor device and a circuit board. In order to solve the above-mentioned problems, the present invention provides a semiconductor device mounted on a circuit board face down, wherein a pedestal portion and a top portion are provided on an aluminum electrode pad portion of the semiconductor device. A bump electrode having a two-step projection, an electrode structure having an inorganic bonding layer formed only on the top of the two-step bump electrode, and a two-step bump electrode on the aluminum electrode pad of the semiconductor device.
It has a mounting structure that electrically connects the step-shaped bump electrodes to the terminal electrodes on the circuit board via the inorganic bonding layer, and aims to realize a highly reliable semiconductor device mounted on the circuit board. Is what you do. The present invention has an electrode structure in which an inorganic bonding layer is formed only on the top of a two-step projection-shaped bump electrode formed directly on an aluminum electrode pad of a semiconductor device.
When a semiconductor device is bonded to a terminal electrode of a circuit board, bonding can be performed at a fine pitch without a short circuit between adjacent bonding layers, and a highly reliable semiconductor device mounting structure can be realized. An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic explanatory view of an electrode structure of a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a schematic explanatory view of a mounting structure of the semiconductor device having the electrode structure of the above embodiment. FIG. In FIG. 1, reference numeral 1 denotes an IC substrate of a semiconductor device, and reference numeral 2 denotes an aluminum electrode pad. Numeral 3 denotes a bump electrode having a two-stage protrusion composed of a pedestal portion and a top portion, and numeral 4 denotes a solder bonding layer formed only on the top portion of the bump electrode having a two-stage protrusion shape. 5 is a passivation film. In FIG. 2, 6 is a circuit board, and 7 is a terminal electrode. An electrode structure and a mounting structure of the semiconductor device configured as described above will be described below with reference to the drawings. First, an Au ball at the tip of an Au wire is fixed onto an aluminum electrode pad 2 of an IC substrate 1 of a semiconductor device in the same manner as in a normal wire bonding technique, and then the Au wire is cut to form a pedestal and a top. To form a bump electrode 3 having a two-step protrusion shape. After that, the solder bonding layer 4 is formed only on the top of the bump electrode 3 having a two-step projection by a transfer method or a printing method. At this time, solder reflow is performed as needed. As described above, it is possible to easily obtain an electrode structure including the bump electrode 3 having a two-step projection and the solder bonding layer 4 on the aluminum electrode pad 2 of a general-purpose semiconductor device. According to the electrode structure of the semiconductor device of the present invention, a bump electrode having a two-step projection can be obtained by a normal wire bonding apparatus by the above-described method. It can be used and is extremely versatile. Further, after the semiconductor device having the electrode structure obtained as described above is positioned face to face at a predetermined position on the circuit board 6, and then mounted 200 to 300
The semiconductor device is mounted by heating to a high temperature of ℃ to melt the solder bonding layer 4 and fuse it to the terminal electrode 7. When the solder bonding layer 4 is melted by heating to the high temperature and connected to the terminal electrode 7, the IC
Since the gap between the substrate 1 and the circuit board 6 can be maintained by the two-stage projecting bump electrodes 3 and the solder bonding layer 4 can be formed only on the top, the spread of the solder is restricted. This makes it possible to obtain a semiconductor device mounting structure which can be connected at a fine pitch without danger of short-circuiting with an adjacent one. According to the mounting structure of the semiconductor device of the present invention, the spread of the solder, which was impossible with the conventional mounting structure using the solder bump electrodes, can be achieved by using the bump electrodes having the two-step projections. Thus, the semiconductor device can be mounted very stably, with high reliability and with high density. In the present embodiment, the bump electrode having a two-step projection is formed by using a wire bonding apparatus. However, the bump electrode may be formed by another method such as plating if the shape is a two-step projection. Although the bump electrode is made of Au, the material is not limited to Au. For example, the bump electrode may be made of another metal such as Cu. Further, the solder bonding layer formed on the top of the bump electrode having a two-step projection may be formed by transferring or printing a solder paste. As described above, according to the semiconductor device electrode and the mounting body of the present invention, it can be formed directly on the aluminum electrode pad portion of the semiconductor device by a normal wire bonding apparatus. Therefore, a general-purpose semiconductor device can be used, and the versatility is extremely high. Further, by having an electrode structure in which an inorganic bonding layer is formed only on the top of the bump electrode having a two-step projection, the spread of the inorganic bonding layer when the semiconductor device is bonded to the terminal electrode of the circuit board is restricted. Is possible, and the inorganic bonding layer has a mounting structure capable of bonding at a fine pitch without short-circuiting with the adjacent, extremely stable and reliable, and
A semiconductor device can be mounted with high density.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic explanatory view of an electrode of a semiconductor device according to an embodiment of the present invention. FIG. 2 is a schematic explanatory view of a package of a semiconductor device having an electrode structure according to one embodiment of the present invention. FIG. 3 is a schematic explanatory view of an electrode of a semiconductor device having a conventional solder bump electrode. FIG. 4 is a schematic explanatory view of a conventional package of a semiconductor device having solder bump electrodes. [Description of Signs] 1 IC substrate of semiconductor device 2 Aluminum electrode pad 3 Two-step protruding bump electrode 4 Solder bonding layer 5 Passivation film 6 Circuit board 7 Terminal electrode 8 IC substrate of semiconductor device 9 Aluminum electrode pad 10 Adhesive metal film DESCRIPTION OF SYMBOLS 11 Diffusion prevention metal film 12 Solder protrusion 13 Passivation film 14 Circuit board 15 Terminal electrode

Claims (1)

Claims: 1. A semiconductor device comprising a semiconductor device mounted face-down on a terminal electrode portion on a substrate, the first device being directly formed on an electrode pad portion of the semiconductor device by a wire bonding method. of the projection portion, the formed on the first projecting portion, and the second with the first parallel cross-sections and the electrode pad portion and small the electrode pad portion than parallel cross-sectional area of the protrusions A bump electrode made of a two-step projection made of Au and a terminal electrode part of the substrate are mounted only on a two-step projection-shaped bump electrode centering on the first projection of the bump electrode.
The semiconductor device is electrically connected via a solder bonding layer formed before, and the solder bonding layer is held around the second protrusion after mounting . Implementation body. 2. An electrode structure comprising a first protrusion, a second protrusion, and a solder bonding layer, wherein the first and second protrusions are formed by a wire bonding method. A cross-sectional area of a horizontal surface of the protrusion is smaller than a cross-sectional area of a horizontal surface of the first protrusion, and the second protrusion is formed on the first protrusion to form a two-step protrusion Au.
An electrode structure, comprising: a bump electrode comprising: a solder bonding layer formed only on a bump electrode having a two-stage protrusion centering on the first protrusion.