JP2709495B2 - Semiconductor element connection method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for connecting semiconductor devices.

[Prior Art] FIG. 5 shows a schematic structure of a conventional flip chip connection of a semiconductor element. In the figure, 1 is a semiconductor element, 2 is a wiring board, 3 is a solder bump, 4 is an electrode provided on each of the semiconductor element 1 and the wiring board 2, and AA 'indicates the center of the semiconductor element. .

In flip-chip connection, electrical connection between the semiconductor element 1 and the electrode 4 of the wiring board 2 can be performed by batch connection in which the solder bumps 3 are heated and melted, so that workability is superior to that of the wire bonding method. Also, wire bonding method and
Unlike the TAB (Tape Automated Bonding) method, the arrangement of the electrodes is not limited to the periphery of the semiconductor element, so that the number of connection terminals can be greatly increased.

However, in this connection structure, as shown in FIG. 6, when a temperature change occurs, a dimensional deviation B occurs due to a difference in the thermal expansion coefficient between the semiconductor element 1 and the wiring board 2, and shear distortion occurs in the solder bump 3. Connection reliability decreases.

Since the shear strain increases with an increase in the center distance between the solder bump 3 and the semiconductor element 1, the area where the solder bump 3 can be arranged is limited due to the allowable shear strain of the solder bump 3, so that the number of terminals and the area are increased. Is difficult to apply to semiconductor devices.

As a means for reducing the shear strain of the solder bumps, a method using a wiring board material having a thermal expansion coefficient close to that of the semiconductor element can be considered, but there is a disadvantage that the wiring board material is limited.

On the other hand, there has been proposed a method (Japanese Patent Laid-Open Publication No. 62-293730) in which a multi-stage bump is formed by laminating solder bumps while supporting them with a polyimide film to reduce shear distortion.

However, the above-described method has a drawback in that the number of necessary members increases and the number of connection steps increases, and thus the price rises because solder bumps are stacked.

FIG. 7 shows a semiconductor element connection structure in which a metal bump is brought into contact with a pressure to obtain an electrical connection. In FIG.
Metal bumps 13 are formed on the respective electrodes 4 of the semiconductor element 1 and the wiring board 2. Pressure is applied to the metal bumps 13 due to the contraction force of the resin 5 at the time of curing, and the metal bumps 13 are pressed.
13 contact each other mechanically, and an electrical connection is obtained.

However, in this connection structure, there are portions where the height of the metal bumps 13 varies and electrical connection cannot be obtained.
In addition, since the coefficient of thermal expansion of the resin 5 is larger than that of the metal bump 13, the pressure is weakened when a temperature change occurs,
However, there has been a problem that connection reliability is lacking because the contact becomes unstable.

[Problems to be solved by the invention]

According to the present invention, the reliability of electrical connection is high with respect to the above-described large shear strain generated between the semiconductor element and the wiring board, variation in bump height, and pressure fluctuation due to the difference in thermal expansion coefficient between the resin and the resin. Further, the present invention provides an inexpensive method for connecting a semiconductor element.

[Means for solving the problem]

According to the present invention, a ball is formed at the tip of a superelastic metal wire inserted through a capillary, and the ball is pressed and joined to an electrode of a portion to be joined, or the superelastic metal wire is connected to an electrode of the portion to be joined by a wedge-shaped tool. A semiconductor element connection method, wherein a wire is cut to form a superelastic metal bump, and an electric connection is made with the superelastic metal bump interposed.

In order to solve the above-mentioned problem, the present invention employs a method of connecting a semiconductor element in which a superelastic metal is interposed, and uses a superelastic metal ball or a superelastic metal with a capillary or wedge type tool using a superelastic metal wire. A super-elastic metal bump formed by pressing and bonding a wire to an electrode of a portion to be bonded is used.

The superelastic metal bump formed as described above may be subjected to heat treatment such as heating and quenching as needed in order to improve superelastic properties.

As the superelastic metal material used for the superelastic metal wire, for example, Ni-Ti, Cu-Al-Ni, Au-Cd, Ag-Cd, Cu-Zn-
Al, Cu-Zn-Sn, Cu-Sn, Fe-Pt, Fe-Pd, In-Tl, Ni-Al, etc. are used, and a super-elastic metal material showing elongation of 0.5% or more as elastic deformation is used. Is desirable.

(Operation)

If the semiconductor element is connected using the above-mentioned super-elastic metal bump, the super-elastic metal receives the heat distortion due to the heat generation of the semiconductor element and the change in the surrounding temperature, and the deformation is repeated within the elastic range even with the repeated distortion. Therefore, it is possible to respond more flexibly and improve the reliability of the electrical connection.

Hereinafter, the contents of the present invention will be specifically described with reference to examples.

〔Example〕

Embodiment 1 FIG. 1 is a cross-sectional view showing a superelastic metal bump forming step for showing an embodiment of the present invention. In FIG. 1, 21 is a semiconductor element, 22 is an electrode, 23 is a capillary, 24 is a superelastic metal wire, 25 is a superelastic metal ball, and 26 is a superelastic metal bump.

Cu-14wt% of wire diameter 25μm for superelastic metal wire 24
As shown in FIG. 1 (a), using Al-4wtNi, a superelastic metal ball was formed by electric discharge machining while blowing nitrogen gas onto the tip of the wire 24 as shown in FIG. 1 (a).

Thereafter, as shown in FIG. 1 (b), the capillary 23 was lowered onto the electrode 22 of the semiconductor element 21, and a superelastic metal ball 25 was bonded to the electrode 22 by applying an ultrasonic wave and a load. At this time, the semiconductor element 21 was heated to 180 ° C. and the atmosphere was inactivated with nitrogen gas.

Thereafter, as shown in FIG. 1C, the capillary 23 was raised and the wire 24 was cut to form a superelastic metal bump 26 on the electrode 22 on the semiconductor element 21.

By repeating the above steps, all the electrodes 22 of the semiconductor element 21
Then, a superelastic metal bump 26 was formed.

Next, as shown in FIG. 2, the super elastic metal bump 26 of the semiconductor element 21 is aligned with the electrode 28 on the substrate 27, and the resin 29 is supplied. The resin 29 was cured by pressing the semiconductor element 21 so as to perform the same. or,
As the connecting means, a pressing method such as a leaf spring may be used instead of holding the pressing force by the resin.

By the above-described semiconductor element connection method, all the superelastic metal bumps 26 and the electrodes 28 can be electrically connected, and the superelastic metal bumps exhibit an elastic strain of 7% and are subjected to a temperature cycle of 0 to 150 ° C. and 1000 times. In the test, good connection reliability was shown without disconnection.

Embodiment 2 FIG. 3 is a cross-sectional view showing a superelastic metal bump forming step for showing Embodiment 2 of the present invention. In FIG. 3, 33
Is a wedge-shaped tool, 34 is a superelastic metal wire, 35 is a superelastic metal bump, 37 is a substrate, and 38 is an electrode on the substrate 37.

For the superelastic metal wire 34, Cu-14wt% of wire diameter 25μm
Using Al-4wt% Ni, the wire 34 set on the tool 33 is lowered onto the electrode 38 of the substrate 37 as shown in FIG. Joined.

Thereafter, as shown in FIG. 3 (b), the tool 33 was raised and the wire 34 was cut to form a superelastic metal bump 35 on the electrode 38 on the substrate 37.

By repeating the above steps, the electrode 38 at a predetermined position on the substrate 37
Then, a superelastic metal bump 35 was formed.

Next, as shown in FIG.
The resin 39 was supplied by aligning 35 with the electrode 32 of the semiconductor element 31, and pressing the semiconductor element 31 so that all the superelastic metal bumps 35 and the electrodes 32 were in contact with each other, thereby curing the resin 39. Further, as the connecting means, a pressing method such as a leaf spring may be used instead of holding the pressing force by the resin.

By the above-described semiconductor element connection method, all the superelastic metal bumps 35 and the electrodes 32 can be electrically connected, and the superelastic metal bumps according to the present embodiment show an elastic strain of 7%, 0 to 150 ° C.,
Even in 1000 temperature cycle tests, good connection reliability was shown without disconnection.

〔The invention's effect〕

With the above-described capillary or wedge-shaped tool of the present invention, a super-elastic metal ball or a super-elastic metal wire is pressed and joined to an electrode of a connected portion to form a super-elastic metal bump, and a semiconductor element is formed via the super-elastic metal. If the connection is made between the substrate and the substrate, the superelastic metal will deform within the elastic range and absorb the stress even if distortion occurs due to heat generation of the semiconductor element or a change in ambient temperature, thereby improving the reliability of electrical connection of the semiconductor element. It is possible to form a superelastic metal bump at low cost.

[Brief description of the drawings]

1 to 4 are cross-sectional views illustrating a method of connecting a semiconductor device according to the present invention, and FIGS. 5 to 7 are cross-sectional views illustrating a conventional method of connecting a semiconductor device using bumps. The figure is shown. 1,21,31 ... semiconductor element, 2,27,37 ... substrate, 3 ... solder bump, 13 ... metal bump, 4,22,28,32,38 ... electrode, 5,29,39 ... … Resin, 23 …… Capillary, 24,34 ……
Superelastic metal wire, 25 ... Superelastic metal ball, 33 ... Wedge tool, 26,35 ... Superelastic metal bump.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshio Ozeki 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture New Nippon Steel Corporation 1st Technical Research Institute (72) Inventor Keisuke Watanabe 1-7-7 Toranomon, Minato-ku, Tokyo No. 12 Oki Electric Industry Co., Ltd. (72) Inventor Takashi Kanamori 1-7-1, Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Yasuo Iguchi 1-7-7 Toranomon, Minato-ku, Tokyo No. 12 Oki Electric Industry Co., Ltd. (56) References JP-A-2-137240 (JP, A) JP-A-57-163919 (JP, A) JP-A-1-192125 (JP, A) JP 2-180036 (JP, A) JP-A-2-185050 (JP, A) JP-A-2-206124 (JP, A)

Claims (2)

(57) [Claims] 1. A ball is formed at the tip of a superelastic metal wire inserted into a capillary, and the ball is pressed and joined to an electrode of a portion to be joined, and then the wire is cut to form a superelastic metal bump. A method of connecting a semiconductor element, wherein electrical connection is made via a superelastic metal bump. 2. A super-elastic metal wire is pressed and joined to an electrode of a portion to be joined by a wedge-shaped tool, and then the wire is cut to form a super-elastic metal bump. A method for connecting a semiconductor element, comprising: connecting.