JPH06151437A - Electrode structure of semiconductor device, its formation, and packaging body - Google Patents

Abstract

PURPOSE:To provide the electrode structure of a semiconductor device which can easily and highly reliably connect the semiconductor device to a circuit board, its manufacturing method, and a mounting body. CONSTITUTION:Bump electrodes 6 with rugged surfaces at their front end sections are provided on the electrode pads 2 of the IC board of a semiconductor device. Joining surfaces 7 are formed on the rugged surfaces of the electrodes 6 and the electrodes 6 for semiconductors are respectively joined to terminal electrodes 9 on a circuit board 8 through the layers 7. Therefore, the joining strengths of the electrodes 6 can be increased by the rugged surfaces at the front end sections of the electrodes and highly reliable junctions can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode structure of a semiconductor device when mounting the semiconductor device on a circuit board, a method of forming the same, and a mounting body, and more particularly to an electrode structure of a semiconductor device mounted face down. And a method of forming the same and a mounting body.

[0002]

2. Description of the Related Art Conventionally, soldering was often used to mount a semiconductor device on a circuit board.
As the package of the semiconductor device has become smaller and the number of connection terminals has increased, the connection terminal interval has become narrower, and it has become increasingly difficult to cope with this with conventional soldering techniques.

Therefore, recently, a method has been devised in which a semiconductor device is directly mounted on a circuit board to reduce the mounting area and to efficiently use the circuit board. In particular, when connecting a semiconductor device to a circuit board, a semiconductor having an electrode structure in which a vapor deposition film of an adhesion metal or a diffusion prevention metal is formed in advance on an aluminum electrode pad, and a solder layer is formed on the vapor deposition film by plating. A mounting structure in which a device is manufactured and the semiconductor device is stacked face down on a circuit board and heated to a high temperature so that the solder and the terminal electrodes of the circuit board are fused together has high mechanical strength after connection and It is said that this is an effective method because it can be connected afterwards (for example, Industrial Research Society, published on January 15, 1980, edited by Japan Microelectronics Association, "IC implementation technology").

An example of a conventional electrode structure of a semiconductor device, a method for forming the same, and a mounting body will be described below with reference to the drawings. FIG. 4 is a schematic explanatory diagram showing a conventional method for forming an electrode for a semiconductor device having a solder bump electrode, FIG. 5 is a schematic explanatory diagram showing an electrode structure, and FIG. 6 is a schematic explanatory diagram showing a mounted body.

4 and 5, 10 is an IC substrate of a semiconductor device, 11 is an electrode pad, 12 is a passivation film, 13 is an adhesion metal film, 14 is a diffusion prevention metal film, 1
5 is a photoresist film. Reference numeral 16 is a solder bump after plating, and 17 is a solder bump after reflow. In FIG. 6, 18 is a circuit board and 19 is a terminal electrode.

An electrode structure of a semiconductor device having a conventional solder bump electrode composed of such components, a method of forming the same, and a mounting body will be outlined below.
First, as shown in FIG. 4A, the IC substrate 1 of the semiconductor device
An adhesion metal film 13 such as Cu and a diffusion preventing metal film 14 such as Cr are formed on the electrode pad 11 of 0 by vapor deposition. After that, as shown in FIG. 4B, the portions other than the electrode portions are covered with the photoresist 15, and the solder is deposited on the diffusion preventing metal film 14 by the plating method to form the mushroom-shaped solder bumps 16 shown in FIG. 4C. obtain. Finally, by performing solder reflow, solder bumps 17 are formed as shown in FIG. 4D to obtain solder bump electrodes having the electrode structure of FIG.

Further, the semiconductor device having the solder bump electrodes thus obtained is aligned at a predetermined position on the circuit board 18 and face-down loaded, and then 20
By heating to a high temperature of 0 to 300 ° C. to melt the solder bumps 17 and fuse the solder bumps 17 to the terminal electrodes 19, a semiconductor device package as shown in FIG. 6 can be obtained.

[0008]

However, the electrode structure of the semiconductor device having the solder bump electrodes as described above, the method for forming the same, and the mounting body are as follows. When the solder is melted by heating it to a high temperature and connecting it to the terminal electrode, the gap between the IC substrate and the circuit substrate cannot be maintained, so that there is a risk that the solder spreads and short-circuits with an adjacent portion. Since the IC substrate and the circuit substrate, which have different thermal expansions, are connected to each other by solder, there is a problem that they are brittle against thermal stress.

The present invention has been made in view of the above problems, and provides an electrode structure of a semiconductor device, a method of forming the same, and a mounting body that can easily and reliably connect the semiconductor device and a circuit board. That is the purpose.

[0010]

In order to solve the above-mentioned problems, an electrode structure of a semiconductor device mounted on a circuit board face down according to the present invention has a protruding electrode formed on an electrode pad portion of the semiconductor device. The structure has an uneven surface at the tip.

Further, the method of forming a semiconductor device electrode mounted on a circuit board face down according to the present invention comprises a step of forming a convex protruding electrode on an electrode pad portion of the semiconductor device, and a step of forming the protruding electrode on the surface. And a step of forming an uneven surface on the tip end portion of the bump electrode by ultrasonically vibrating the flat base.

Further, according to the mounting body of a semiconductor device mounted on a circuit board face down according to the present invention, a protruding electrode having an uneven surface at a tip portion formed on an electrode pad portion of the semiconductor device is connected to a circuit via a bonding layer. It is configured by being electrically connected to the terminal electrodes on the substrate.

The bump electrodes can be formed by a method such as wire bonding or plating using metal such as Au. The bonding layer may be made of a conductive adhesive or solder.

[0014]

As described above, by providing the protruding electrode having the uneven surface at the tip on the electrode pad portion of the semiconductor device, when the semiconductor device is bonded to the terminal electrode of the circuit board,
The bonding area between the tip surface of the protruding electrode and the terminal electrode of the circuit board can be increased, and good electrical and mechanical bonding can be achieved, and a highly reliable semiconductor device package can be obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory view showing a method of forming an electrode for a semiconductor device according to an embodiment of the present invention, FIG. 2 is a schematic explanatory view showing an electrode structure of a semiconductor device by the electrode forming method of the above embodiment, and FIG. It is a schematic explanatory drawing which shows the mounted body of the semiconductor device which has an example electrode.

1 and 2, 1 is an IC substrate of a semiconductor device, 2 is an electrode pad, and 3 is a protruding electrode. Four
Is a flat base with a built-in ultrasonic transmitter, 5 is an uneven surface formed on the surface of the flat base 4, and 6 is a protruding electrode having an uneven surface at the tip. In FIG. 3, 7 is a bonding layer made of a conductive adhesive, 8 is a circuit board, and 9 is a terminal electrode.

The outline of the electrode structure of the semiconductor device including such components, the forming method thereof, and the mounting body will be described below. First, the bump electrode 3 is formed on the electrode pad 2 of the IC substrate 1 of the semiconductor device shown in FIG. 1A by a known Au plating method. Next, FIG. 1 (b)
As shown in, the IC substrate 1 having the protruding electrodes 3 formed thereon is placed face down on a flat base 4 having an uneven surface 5 formed on its surface. Further, as shown in FIG. 1C, the flat base 4
By operating the ultrasonic oscillator built into the substrate, the flat base 4 is vibrated to form an uneven surface at the tip of the protruding electrode 3. As described above, the protruding electrode 6 having the uneven surface formed at the tip portion shown in FIG. 2 can be easily obtained.

Further, after the bonding layer 7 made of a conductive adhesive is formed on the uneven surface of the tip portion of the bump electrode 6 of the semiconductor device thus obtained by the transfer method or the printing method, the semiconductor device is mounted on the circuit board. After aligning at a predetermined position of 8 and stacking face down, the bonding layer 7 is cured to bond the protruding electrode 6 to the terminal electrode 9. From the above, FIG.
A semiconductor device package mounted on a circuit board is obtained face down as shown in FIG.

When connecting the semiconductor device electrode to the terminal electrode 9 of the circuit board 8, the gap between the IC board 1 and the circuit board 8 can be maintained by the protruding electrode 6. For this reason, it is possible to regulate the spread of the bonding layer 7, and it is possible to obtain a semiconductor device package that can be connected at a fine pitch without the risk of short-circuiting with an adjacent portion.

Further, by using the protruding electrode having the uneven surface at the tip, the bonding layer enters into the uneven portion of the protruding electrode to increase the adhesive force with the terminal electrode of the circuit board, which is extremely stable and reliable. The semiconductor device can be mounted with high density and high density.

In this embodiment, the bump electrode is formed by using the plating method using Au, but if the shape is a projection, it may be formed by a wire bonding method using Au wire. Further, in this embodiment, the bonding layer made of a conductive adhesive is formed on the protruding electrodes by the transfer method or the printing method, but the bonding layer may be formed in advance on the terminal electrodes of the circuit board. Further, the composite layer is not limited to the conductive adhesive, but may be another bonding material such as solder.

[0022]

As described above, according to the present invention, since the uneven surface can be easily formed at the tip of the protruding electrode of the semiconductor device, the versatility is extremely high. Furthermore, by providing an uneven surface at the tip of the protruding electrode of the semiconductor device, when the semiconductor device is bonded to the terminal electrode of the circuit board, the bonding area between the uneven surface of the protruding electrode and the terminal electrode surface of the circuit board is increased. Therefore, an extremely stable and highly reliable semiconductor device package can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a method for forming an electrode for a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a schematic explanatory diagram showing an electrode structure of a semiconductor device according to an embodiment of the present invention.

FIG. 3 is a schematic explanatory view showing a semiconductor device mounting body according to an embodiment of the present invention.

FIG. 4 is a schematic explanatory view showing a method for forming an electrode for a semiconductor device having a conventional solder bump electrode.

FIG. 5 is a schematic explanatory view showing an electrode structure of a conventional solder bump electrode.

FIG. 6 is a schematic explanatory view showing a mounting body of a semiconductor device having a conventional solder bump electrode.

[Explanation of symbols]

 1 IC substrate of semiconductor device 2 Electrode pad 3 Projection electrode 4 Planar base with built-in ultrasonic oscillator 5 Concavo-convex surface 6 Projection electrode with concavo-convex surface formed at the tip 7 Bonding layer 8 Circuit board 9 Terminal electrode

Claims (8)

[Claims] 1. An electrode structure of a semiconductor device mounted face down on a circuit board, wherein a protruding electrode formed on an electrode pad portion of the semiconductor device has an uneven surface at its tip. Device electrode structure. 2. The electrode structure of a semiconductor device according to claim 1, wherein the protruding electrode is made of Au. 3. A method of forming electrodes for a semiconductor device to be mounted face down on a circuit board, comprising the steps of forming a convex protruding electrode on an electrode pad portion of the semiconductor device, and forming the protruding electrode on the surface. By pressing the flat base having irregularities and ultrasonically vibrating the flat base,
And a step of forming an uneven surface on the tip of the bump electrode. 4. The method for forming an electrode for a semiconductor device according to claim 3, wherein the protruding electrode is formed by a plating method using Au. 5. The protruding electrode is formed of Au wire by a wire bonding apparatus.
A method for forming an electrode for a semiconductor device as described above. 6. A semiconductor device mounting body mounted face down on a circuit board, wherein a protruding electrode having an uneven surface at a tip end portion formed on an electrode pad portion of the semiconductor device is a circuit via a bonding layer. A semiconductor device mounting body, which is electrically connected to a terminal electrode on a substrate. 7. The semiconductor device package according to claim 6, wherein the bonding layer is made of a conductive adhesive. 8. The semiconductor device package according to claim 6, wherein the bonding layer is made of solder.