JPH05136151A - Method of forming electrode of semiconductor device and packaged body - Google Patents

Abstract

PURPOSE:To obtain a method of forming electrodes of a semiconductor device and a packaged body wherein a semiconductor device can be simply and highly reliablly connected with a circuit board. CONSTITUTION:Protruding type bump electrodes 3 are arranged on aluminum electrode pads 2 of an IC substrate 1 in a semiconductor device, and solder 7 is effectively transferred onto the bump electrodes 3 from a base member 5 free from solder wettability, thereby forming electrodes composed of the bump electrodes 3 and the transferred solder 7. A packaged body is so constituted that a semiconductor device is electrically connected with terminal electrodes on a circuit board, in a face down manner via the solder 7. Hence the contamination of a semiconductor device can be evaded by forming the solder 7 on the bump electrode 3 by transferring. Control of the speed of a bonding layer is enabled by the protruding type bump electrodes 3, and fine pitch bonding 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 forming method for mounting a semiconductor device on a circuit board and its mounting body, and more particularly to an electrode forming method and mounting body for a semiconductor device mounted face down. Regarding

[0002]

2. Description of the Related Art Conventionally, soldering has been often used for mounting a semiconductor device on a circuit board. In recent years, however, due to the miniaturization of the package of the semiconductor device and the increase in the number of connection terminals, the connection terminal spacing has become narrow. It has become increasingly difficult to deal with the conventional soldering technology.

Therefore, recently, there has been devised a method of directly mounting a bare semiconductor device on a circuit board to reduce the mounting area and efficiently use it.

In particular, when connecting a semiconductor device to a circuit board, an electrode structure is formed in advance on an aluminum electrode pad of the semiconductor device by a vapor deposition film of a contact metal or a diffusion preventing metal and a solder layer formed by plating on the vapor deposition film. The mounting structure in which the semiconductor device is turned down (face down) and heated to a high temperature to fuse the solder to the terminal electrodes of the circuit board is effective because the mechanical strength after connection is strong and the connection can be made all at once. It is said to be a method. (For example, "Industrial Research Council, published January 15, 1980, edited by Japan Microelectronics Association," IC mounting technology "). An example of the conventional electrode forming method and mounting method of the semiconductor device described above with reference to the drawings. Will be described.

FIG. 4 is a schematic explanatory view of an electrode forming method of a conventional semiconductor device having a solder bump electrode, FIG. 5 is a schematic explanatory view of an electrode structure of the solder bump electrode, and FIG. 6 is a schematic diagram of the semiconductor device. It is a schematic explanatory drawing of a mounted body.

In FIG. 4, 10 is an IC substrate of a semiconductor device, and 11 is an aluminum electrode pad. Reference numeral 12 is an adhesion metal film, and 13 is a diffusion prevention metal film. Reference numeral 14 is a passivation film, and 15 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.

The electrode forming method and the mounting body of the semiconductor device having the conventional solder bump electrodes configured as described above will be outlined below.

First, as shown in FIG. 4A, an adhesion metal film 12 such as Cu and a diffusion prevention metal film 13 such as Cr are formed on an aluminum electrode pad 11 of an IC substrate 10 of a semiconductor device by vapor deposition. To do. Thereafter, 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 13 by the plating method to form the mushroom-shaped solder bumps shown in FIG. 4C. Get 16. Finally, by performing solder reflow, solder bumps 17 are formed as shown in FIG. 4D, and solder bump electrodes having the electrode structure shown in FIG. 5 are obtained.

Further, the semiconductor device having the solder bump electrodes obtained as described above is aligned at a predetermined position on the circuit board 18 and is loaded face down, and then 2
The solder bumps 17 are melted by heating to a high temperature of 00 to 300 ° C., and the solder bumps 17 are fused to the terminal electrodes 19 to obtain a mounted body of the semiconductor device with the mounting structure of FIG.

[0010]

However, in the electrode forming method of the semiconductor device and the mounting body as described above,
1. In order to form the solder bumps by the plating method, it is necessary to clean the contamination of the semiconductor device from the plating solution, and the electrode forming method becomes complicated and lacks versatility. 2. When heating to high temperature to melt the solder and connect it to the terminal electrode,
Since the gap between the IC substrate and the circuit substrate cannot be maintained, there is a risk that the solder spreads and short-circuits with the adjacent one. Had problems such as.

The present invention has been made in view of the above problems, and an object of the present invention is to easily and reliably connect a semiconductor device and a circuit board at a fine pitch. An object is to provide a method for forming electrodes of a semiconductor device and a mounting body.

[0012]

In order to solve the above problems, the present invention provides a semiconductor device mounted face down on a circuit board, wherein bump electrodes are provided on the aluminum electrode pad of the semiconductor device, and the bump electrodes are provided separately. After the bump electrode is contacted with the solder paste formed according to the electrode pattern on the prepared base material with no solder wettability, the solder paste is heated above the melting temperature of the solder paste to transfer the solder onto the bump electrode to form a semiconductor. After forming the electrodes of the device, the bump electrodes are bonded to the terminal electrodes by aligning them with the terminal electrodes of the circuit board and heating them to obtain a semiconductor device package, which is highly reliable. It is intended to realize mounting of a semiconductor device on a circuit board.

[0013]

According to the present invention, electrodes can be formed without contaminating the semiconductor device by transferring the solder from the base material having no solder wettability onto the bump-shaped bump electrodes formed on the aluminum electrode pad portion of the semiconductor device. When the semiconductor device is joined to the terminal electrode of the circuit board, the solder can be joined at a fine pitch without short-circuiting with the adjacent one, and a highly reliable semiconductor device mounting body can be realized.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrode forming method for a semiconductor device and a mounting body according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic explanatory view of an electrode forming method of a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a schematic explanatory view of an electrode structure of a semiconductor device by the electrode forming method of the above embodiment. 3A and 3B are schematic explanatory views of a semiconductor device package according to an embodiment of the present invention.

In FIG. 1, 1 is an IC substrate of a semiconductor device, and 2 is an aluminum electrode pad. Reference numeral 3 is a bump-shaped bump electrode, and 4 is a passivation film. Reference numeral 5 is a base material having no solder wettability, and 6 is a solder paste. 7 is a solder transferred onto the bump electrode. In FIG. 3, 8 is a circuit board and 9 is a terminal electrode.

The electrode forming method and the mounting body of the semiconductor device configured as described above will be described below with reference to the drawings.

First, as shown in FIG. 1A, the aluminum electrode pad 2 of the IC substrate 1 of the semiconductor device is manufactured by a known method.
A bump-shaped bump electrode 3 is formed on the top.

Further, as shown in FIG. 1B, a solder paste 6 is formed on a base material 5 having no solder wettability, such as alumina or glass, by a screen printing method in accordance with an electrode pattern of a semiconductor device. ..

Next, as shown in FIG. 1C, after the bump electrode 3 and the solder paste 6 are aligned with each other, the bump electrode 3 is heated to a temperature higher than the melting temperature of the solder paste in a contact state. The solder 7 is transferred onto the top. At this time, the molten solder does not get wet on the side of the base material 5 having no solder wettability.
As shown in (d), the solder 7 can be efficiently transferred to the bump 3 side.

By the method described above, the bump electrode 3 having a projection shape is formed on the aluminum electrode pad 2 of the semiconductor device as shown in FIG.
Electrodes suitable for mounting a semiconductor device can be easily formed with the face-down of the solder 7 transferred with the above.

The semiconductor device package of this embodiment is
After forming the bump electrodes 3 on the protrusions and the electrodes made of the transferred solder 7 on the aluminum electrode pads 2 of the semiconductor device by the electrode forming method of the semiconductor device of the present invention, as shown in FIG. After aligning the positions and stacking face down, the solder 7 on the bump electrodes 3 is remelted by being heated above the melting temperature of the solder and bonded to the terminal electrodes 9 to obtain a semiconductor device package. ..

According to the above method, when the solder 7 on the bump electrode 3 is melted and joined to the terminal electrode 9, the gap between the IC substrate 1 and the circuit substrate 8 of the semiconductor device is maintained by the bump electrode 3 having a projecting shape. As a result, the spread of the remelted solder can be regulated, there is no risk of short-circuiting with the adjacent solder, and a semiconductor device package that can be connected at a fine pitch can be obtained.

The semiconductor device mounting body of the present invention is extremely stable by the above-described method, because the bump electrodes can control the spread of the solder, which was impossible with the conventional mounting body using the solder bump electrodes. Semiconductor devices can be mounted with high reliability and high density.

In this embodiment, if the bump electrode is formed in the shape of a two-step protrusion, the effect of restricting the spread of the solder can be more remarkably exhibited.

In the present embodiment, the bump electrodes having a protruding shape are formed by using a plating method, but if the shape is a protruding shape, they may be formed by another method such as wire bonding.

Further, although the solder paste is formed on the base material having no solder wettability, it may be formed on the surface of any base material coated with a material having no solder wettability. If used, the complete transfer of the solder onto the bump electrode can be more effectively performed.

Further, although the low melting point alloy foil is made of solder, the material is not limited to solder, and may be made of other metal as long as it is made of a low melting point alloy.

[0029]

As described above, according to the electrode forming method and the mounting body of the semiconductor device of the present invention, the solder wettability is provided on the bump-shaped bump electrode formed on the aluminum electrode pad portion of the semiconductor device. By efficiently transferring solder from a non-base material to form electrodes, bump electrodes and solder electrodes can be formed on the semiconductor device without contamination of the semiconductor device by plating liquid or the like, which makes it extremely versatile. high.

Further, by having the electrode structure in which the solder is transferred onto the bump-shaped bump electrodes of the semiconductor device, the spread of the solder can be regulated when the semiconductor device is bonded to the terminal electrode of the circuit board, and the semiconductor device can be controlled. When mounting on a circuit board, solder can be joined at a fine pitch without short-circuiting with adjacent parts, which is extremely stable and reliable, and
Semiconductor devices can be mounted at high density.

[Brief description of drawings]

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

FIG. 2 is a schematic explanatory view of an electrode structure of a semiconductor device according to the electrode forming method of the semiconductor device of the present invention.

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

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

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

FIG. 6 is a schematic explanatory view of a mounting structure of a semiconductor device mounted by a conventional solder bump electrode.

[Explanation of symbols]

 1 IC substrate of semiconductor device 2 Aluminum electrode pad 3 Protruding bump electrode 4 Passivation film 5 Base material without solder wettability 6 Solder paste 7 Transferred solder 8 Circuit board 9 Terminal electrode 10 IC board 11 Aluminum electrode pad 12 Adhesion Metal film 13 Diffusion prevention metal film 14 Passivation film 15 Photoresist film 16 Solder bump after plating 17 Solder bump after reflow 18 Circuit board 19 Terminal electrode

Claims (11)

[Claims] 1. A method for forming electrodes of a semiconductor device mounted face down on a circuit board, wherein bump electrodes having protrusions are provided on an aluminum electrode pad portion of the semiconductor device, and the bumps are provided on a separately prepared base material having no solder wettability. An electrode forming method for a semiconductor device, comprising: contacting the bump electrode with a solder paste formed in accordance with an electrode pattern, and then heating the solder paste to a temperature higher than a melting temperature of the solder paste to transfer the solder onto the bump electrode. 2. The method for forming an electrode of a semiconductor device according to claim 1, wherein the bump electrode having a projection shape has a two-step projection shape. 3. The method for forming an electrode of a semiconductor device according to claim 1, wherein the material of the bump-shaped bump electrode is Au. 4. The method for forming an electrode of a semiconductor device according to claim 1, wherein the solder paste is formed on the base material having no solder wettability by screen printing. 5. The method for forming an electrode of a semiconductor device according to claim 1, wherein the material of the base material having no solder wettability is alumina. 6. The method for forming an electrode of a semiconductor device according to claim 1, wherein the material of the base material having no solder wettability is glass. 7. In a semiconductor device mounting body to be mounted face down on a circuit board, after solder is transferred from a base material having no solder wettability to bump electrodes on aluminum electrode pads of the semiconductor device, the terminal electrodes of the circuit board are mounted. A semiconductor device mounting body, characterized in that the semiconductor device is mounted by bonding the bump electrodes to the terminal electrodes by aligning and stacking with each other and heating. 8. The semiconductor device package according to claim 7, wherein the bump electrode has a two-step projection shape. 9. The package of a semiconductor device according to claim 7, wherein the material of the bump electrode is Au. 10. The semiconductor device package according to claim 7, wherein the material of the base material having no solder wettability is alumina. 11. The package of a semiconductor device according to claim 7, wherein the material of the base material having no solder wettability is glass.