JPH0745664A - Mounting method for semiconductor device - Google Patents

Abstract

PURPOSE:To eliminate the need of forming projecting electrodes in a semiconductor device and, at the same time, to reduce the number of manufacturing processes of the device by removing oxide films from the surfaces of electrodes by performing reverse sputtering and depositing metallic films on the surfaces of the electrodes. CONSTITUTION:Individually and separately fed multiple semiconductor devices 1 are simultaneously put in the chamber of a sputtering device and oxide films formed on Al electrodes are selectively removed by reverse sputtering. After removing the oxide films, metallic films 3 and second metallic films 4 are separately sputtered. Then solder paste 6 is supplied to the surfaces of circuit boards coated with a solder resist 8 and balls 10 coated with an easily solderable metal 9 are arranged on the printed solder paste 6. Thereafter, the solder is melted by counterposing the device 1 to the board 5 and heating the balls 10 while the electrodes 2 of the device 1 are pressed against the balls 10 arranged on the connection pads of the board 5. Then the circuit board 5 is dipped in an etchant so as to selectively remove the second metallic films 4 composed of CuNi.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device connection technique, and more particularly to a technique for face-down connection of a semiconductor device to a circuit board.

[0002]

2. Description of the Related Art A conventional face-down connection method will be described.

Conventionally, when face-down connecting a semiconductor device to a circuit board, it was necessary to previously form protruding electrodes on the electrodes of the semiconductor device. A method of forming a protruding electrode by plating in a wafer state is known as long as it is a semiconductor device manufactured by the manufacturer or a semiconductor device that can be obtained in a wafer state. As shown in FIG. 4A, first, the electrode 1 of the semiconductor device 11 is formed by reverse sputtering.
The insulating protective film 21 made of an oxide film on 4 is removed, and then the metal thin film 12 is laminated on the semiconductor device 11 by sputtering. Next, a resist 13 is applied on the metal thin film 12, and only the portion of the electrode 14 above which the protruding electrode is to be formed is opened by photolithography. Then, the metal thin film 12
Is used as a cathode, and the plated metal 15 is formed by electrolytic plating. Then, the resist 13 is removed to remove the unnecessary metal thin film 1.
By removing 2 by etching using the plated metal 15 as a mask, a protruding electrode composed of the metal thin film 12 and the plated metal 15 can be formed (FIG. 4B).

At this time, when the metal 15 is solder, by melting the solder, it is possible to obtain a hemispherical protruding electrode by the surface tension of the solder as shown in FIG. 4 (c).

Further, as shown in FIG. 5, the oxide film 21 on the electrode 14 of the semiconductor device 11 is removed by reverse sputtering, and then the metal thin film 12 is vapor-deposited on the electrode 14 by using the metal mask 16. Subsequently, the metals 17a and 17b forming the solder
Are sequentially deposited. Finally, the metals 17a and 17b are melted,
A hemispherical protruding electrode as shown in (c) is obtained.

After the protruding electrodes are formed by the method as described above, the semiconductor devices are individually divided by dicing.

On the other hand, as shown in FIG. 6, on the electrode 14 of the semiconductor device 11 which is delivered from another company and which has been previously divided into individual parts, a protruding electrode is formed by a ball bonding method applying a wire bonding technique using a fine metal wire. There is known a method of forming the. The thin metal wire 18 supplied and supported by the capillary 19 is melted to form a metal ball 20, which is pressed against the electrode 14 of the semiconductor device 11 and is heated or applied with ultrasonic waves, or both are used together. 11 destroys the oxide film on the electrode 14 of the metal ball 20.
After that, the thin metal wire is cut to form a protruding electrode.

After forming the bump electrodes in this way, the semiconductor device is individually divided, the bump electrodes are formed on the previously divided semiconductor devices, and subsequently, they are connected to the circuit board by using the face-down connection method.

When the protruding electrode is Au, the protruding electrode is
A method is known in which a conductive paste containing g-Pd is transferred, aligned and pressed onto a connection pad of a circuit board, and then the conductive paste is heat-cured to make a connection.

When the protruding electrodes are solder, flux is applied on the circuit board in advance, the connection pads of the circuit board and the protruding electrodes are aligned and pressed. Next, a method is known in which the solder is melted and connected in this state by passing it through a reflow furnace.

[0011]

However, the conventional technique has the following problems. Obtaining semiconductor devices in the wafer state is possible when semiconductor device manufacturers use their own semiconductor devices, but when purchasing semiconductor devices of other companies, they are usually delivered separately. However, it is impossible to obtain it in a wafer state. It is not practical to form the protruding electrodes on the individually divided semiconductor devices by electrolytic plating or vapor deposition because the cost is significantly increased and the efficiency is poor. Further, even if it is available in a wafer state, the process of forming the protruding electrode by the electrolytic plating method has many steps and is complicated, and the cost of the semiconductor device is significantly increased.

On the other hand, when the protruding electrodes are formed on the individually divided semiconductor devices by the ball bonding method, as the number of electrodes increases, the forming time of the protruding electrodes significantly increases and the yield also decreases. Further, since there is a large variation in the height of the protruding electrodes, there are many problems such as poor connection during face-down connection and poor reliability. Furthermore, Sn / Pb solder, which is widely and commonly used, cannot be formed on Al, which is often used as an electrode of a semiconductor device, by a ball bonding method. For the reasons described above, it is difficult to easily and inexpensively form the protruding electrodes on the semiconductor devices obtained by dividing the semiconductor devices individually.

As described above, forming the protruding electrodes on the semiconductor device causes a problem in that the cost of the circuit module formed by connecting the semiconductor devices face down is increased.

[0014]

The present invention has been made to solve the above-mentioned problems, and in a method of mounting a semiconductor device on a circuit board, a step of exposing electrodes of the semiconductor device, and the semiconductor device. A step of forming a metal film on the electrode exposed surface side, a step of supplying a solder paste onto the connection pads of the circuit board, and a sphere covered with a solder-philic metal on the solder paste of the circuit board. After aligning the step, the semiconductor device on which the metal film is formed, and the circuit board on which the sphere is arranged, the solder paste on the circuit board is melted and heated to form the connection pads of the circuit board and the electrodes of the semiconductor device. And a step of electrically removing the solder paste non-adhesive region of the metal film of the semiconductor device, and a method of mounting the semiconductor device.

[0015]

As described above, in the case of individually divided semiconductor devices, a large number of semiconductor devices are processed at one time, and in the case of a semiconductor device in a wafer state, reverse sputtering is performed while the wafer state is maintained. By removing the upper oxide film and subsequently depositing the metal film, it becomes unnecessary to form the protruding electrode on the semiconductor device. In addition, the number of steps can be reduced.

[0016]

EXAMPLE A first example of the present invention will be described with reference to FIGS.
A second embodiment will be described.

(First Embodiment) A large number of semiconductor devices 1 delivered separately are placed in a chamber of a sputtering apparatus at the same time, and reverse sputtering is performed first to form an insulating oxide film formed on the semiconductor device 1. Of 21, the oxide film formed on the surface of the Al electrode 2 is selectively removed. Subsequently, the metal film 3 made of Ti and the second metal film 4 made of CuNi are sputtered by about 0.1 to 0.3 μm. At this time, the oxide film may be removed and the metal film may be formed on the semiconductor device in a wafer state by the same method, instead of the semiconductor device which is individually divided, and then the semiconductor device may be individually divided by dicing.
Normally, a strong oxide film 21 is formed on the surface of the Al electrode 2 of the semiconductor device 1, and good conductivity cannot be obtained if a metal film is deposited without selectively removing the oxide film by reverse sputtering. . Further, Ti is used as the first metal film 3, but this is used for the electrode 2 and the second metal film (CuNi) 4
In order to obtain an adhesion force with, and if it achieves this purpose, it is not limited to Ti and TiW may be used.

On the other hand, the circuit board 5 for connecting the semiconductor device 1
A wiring material 7 made of Cu is formed on the surface of, and is almost covered with a solder resist 8 except for the connection pad portion which is a semiconductor device connection region. As a method of forming the solder resist 8, there is a method of screen printing in a required shape, or a method of using a photosensitive solder resist to open only the connection pad portion by a photolithography method to further improve accuracy. Further, by applying Au plating or Ni plating + Au plating to the outermost surface of the connection pad, the wettability of the solder can be improved when the solder is melted in the subsequent process.

Next, Sn / Pb = 60/4 is screen-printed on the circuit board 5 covered with the solder resist 8.
The eutectic solder solder paste 6 of 0 is supplied. Next, the sphere 10 covered with the solder-philic metal 9 is placed on the printed solder paste 6. The material of the sphere is Au, Cu,
A metal having a solder-philic property such as Ni, Sn / Pb high-melting-point solder may be used alone, or a metal, ceramic, or resin whose surface is coated with a solder-friendly metal may be used. Here, a sphere obtained by plating a ceramic sphere with Ni and Au was used.

As shown in FIG. 1, the semiconductor device 1 and the circuit board 5 are opposed to each other, the electrode 2 of the semiconductor device 1 and the sphere 10 arranged on the connection pad of the circuit board 5 are aligned, and both are pushed. Hit In this state, the semiconductor device 1 and / or the circuit board 5 is heated to a temperature equal to or higher than the melting point of the solder paste 6 to melt the solder, and the surface of the sphere 10, the connection pad of the circuit board 5, and the metal film 4 of the semiconductor device 1 are melted. As shown in FIG. 2, the semiconductor device 1 and the circuit board 5 are electrically and mechanically connected to each other. At this time, the sphere 10 holds the semiconductor device 1 and the circuit board 5 at a constant distance, and the surface tension of the solder limits the amount of spread of the solder.

Subsequently, the circuit module in which the semiconductor device 1 is connected to the circuit board 5 is dipped in an etching solution of CuNi to selectively remove the second metal film 4 made of CuNi. As the etching solution, there are a solution of Alka etch solution (trade name) sold by Yamatoya Shokai, diluted with water about 5 times, and a solution of nitric acid diluted with water. The metal film 4 made of CuNi formed on the surface of the semiconductor device 1 is very thin and the etching time is short, and the Cu-Sn alloy layer formed at the connection portion is difficult to dissolve in this etching solution. It is possible to selectively remove only unnecessary CuNi. Next, the first metal film 3 made of Ti
Are selectively removed by etching with a mixed solution of EDTA, hydrogen peroxide solution, and ammonia water. Thus, FIG.
As described above, a circuit module in which the semiconductor device 1 is mounted can be obtained.

(Second Embodiment) A large number of semiconductor devices 1 separately delivered are placed in a chamber of a sputtering apparatus at the same time, and first, reverse sputtering is performed to perform insulation oxidation on the semiconductor device 1. Of the film 21, the oxide film formed on the surface of the Al electrode 2 is selectively removed. Continue to TiW
A first metal film 3 made of Cu and a second metal film 4 made of Cu
Is sputtered by about 0.1 to 1 μm. At this time, a semiconductor device in a wafer state may be used as in the first embodiment.

On the other hand, the circuit board 5 for connecting the semiconductor device 1
A wiring material 7 made of Cu is formed on the surface of the substrate, and is covered with a solder resist 8 as in the first embodiment except the connection pad portion which is the semiconductor device connection region. Further, by applying Au plating to the outermost surface of the connection pad, the wettability of the solder can be improved when the solder is melted in a later step.

Next, Sn / Pb = 60 / by screen printing on the circuit board 5 covered with the solder resist 8.
A solder paste 6 of 40 eutectic solder is supplied. Next, the solder-friendly metal 9 is applied onto the printed solder paste 6.
The sphere 10 coated on the base is placed. Here, a Ni ball having a surface plated with Au was used.

As shown in FIG. 1, the semiconductor device 1 and the circuit board 5 are opposed to each other, and the semiconductor device 1 and the circuit board 5 are electrically and mechanically connected as shown in FIG. 2 by the same process as in the first embodiment. To do.

Subsequently, the circuit module in which the semiconductor device 1 is connected to the circuit board 5 is immersed in a Cu etching solution,
The second metal film 4 made of Cu is selectively removed. As the etching solution, there are an alkaline etch solution (trade name) sold by Yamatoya Shokai, diluted with water about 10 times, and nitric acid diluted with water. Next, the first metal film 3 made of TiW is selectively removed by etching with a mixed solution of EDTA, hydrogen peroxide solution, and ammonia water. Thus, as shown in FIG. 3, a circuit module in which the semiconductor device 1 is mounted is obtained.

[0027]

As described above, according to the present invention, it becomes unnecessary to form the protruding electrode on the semiconductor device regardless of whether the semiconductor device is individually divided or in a wafer state, and the number of steps can be drastically reduced. Since reduced face-down connection is possible, a highly reliable circuit module can be obtained inexpensively and easily.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part for explaining an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an essential part for explaining an embodiment of the present invention.

FIG. 3 is a cross-sectional view of an essential part for explaining an embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a conventional example.

FIG. 5 is a cross-sectional view showing a conventional example.

FIG. 6 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 1 Semiconductor Device 2 Al Electrode 3 First Metal Film 4 Second Metal Film 5 Circuit Board 6 Solder Paste 7 Wiring 8 Solder Resist 9 Solder Resistant Metal 10 Ball

Claims (1)

[Claims] 1. A method of mounting a semiconductor device on a circuit board, the step of exposing electrodes of the semiconductor device, the step of forming a metal film on the electrode exposed surface side of the semiconductor device, and the step of connecting pads on the circuit board. A step of supplying a solder paste to the circuit board, a step of disposing a sphere covered with a solder-philic metal on the solder paste of the circuit board, a semiconductor device having the metal film formed thereon, and a circuit board having the sphere arranged thereon. After aligning and, the step of melting and heating the solder paste on the circuit board to electrically connect the connection pads of the circuit board and the electrodes of the semiconductor device, and the solder paste non-bonding of the metal film of the semiconductor device. A method for mounting a semiconductor device, comprising: a step of etching away an adhesion region.