JP2574145B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] There is a hybrid type semiconductor device in which a metal bump is provided on a surface of a semiconductor chip and a plurality of semiconductor chips are connected to face each other via the metal bump in order to improve the degree of integration. . When this structure is used in a semiconductor device such as gallium arsenide or indium antimony that needs to be used after being cooled to an extremely low temperature, the metal bump is easily broken due to metal fatigue based on thermal expansion and contraction. In particular, when one chip is made of a different kind of semiconductor such as silicon and the other is gallium arsenide, the tendency is large. To avoid this drawback, the height of the metal bump may be increased, but this height is limited by the thickness of the photoresist due to the method of manufacturing the metal bump. In order to avoid this limitation, a multi-layer structure may be used, but it is not easy to form a multi-layer structure due to a positioning error. In view of the above, the above-described drawbacks have been solved by realizing a high-height metal bump as a multilayer in which the area becomes larger in the upper layer and the thickness of the upper layer is sufficiently thick.

[Industrial applications]

The present invention relates to an improvement in a hybrid semiconductor device in which a plurality of semiconductor chips are connected via metal bumps. In particular, the present invention relates to an improvement for increasing the height of the metal bump.

[Conventional technology]

In order to improve the degree of integration, a thick columnar metal film called a metal bump is formed on the surface of the semiconductor chip, and two semiconductor device chips having the metal bump on the surface are opposed to and contact with each other. There is a hybrid type semiconductor device that is connected through a.

[Problems to be solved by the invention]

However, since the carrier mobility of gallium arsenide or the like becomes large at extremely low temperatures, it is desirable to use the gallium arsenide semiconductor device at extremely low temperatures. In addition, it is necessary to use an optical semiconductor device for infrared light such as indium antimony at an extremely low temperature. Therefore, these semiconductor devices have many opportunities to reciprocate between room temperature and extremely low temperature.

When a hybrid semiconductor device connected via a metal bump is exposed to the above-described thermal cycling, the metal bump often breaks due to expansion and contraction. This tendency is significant when the chip is composed of a combination of different types of semiconductors, such as when one chip is silicon and the other chip is gallium arsenide, and the disadvantage is significant.

In order to prevent this, the height of the metal bumps may be increased. However, since the metal bumps are generally formed by using a lift-off method, the height is limited by the thickness of the photoresist film. The limit is about 6 μm, and it is not easy to increase the height of the metal bumps to avoid the above-mentioned disadvantages.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a semiconductor device in which the height of a metal bump is high and which is not damaged even when subjected to thermal cycling.

[Means for solving the problem]

FIG. 1 is a cross-sectional view of the metal bump 10 according to the gist of the semiconductor device according to the present invention. In a semiconductor device according to the present invention, in a semiconductor device in which a plurality of semiconductor device chips are connected via metal bumps 10, the metal bumps 10 are formed by using a first resist pattern having a first opening. A lower layer 6 formed on the base exposed in the second opening and a second resist pattern having a second opening larger than the first opening, using the lower layer 6 and the lower layer 6 exposed in the second opening. The semiconductor device has a multilayer structure including an upper layer 9 formed thereon, and the area of the upper layer 9 is larger than the area of the lower layer 6.

[Action]

To form a metal bump having a high height, the metal bump may be formed in a multilayer structure. However, the metal bump cannot be laminated accurately due to an alignment error. Since it is difficult to form a film, it is difficult to form a multilayer metal bump.

Therefore, in order to avoid these restrictions, the area is increased as the upper layer is formed, so that a margin for alignment error is secured, and a photoresist film for forming the upper layer can be applied. And a metal bump having a high height is realized.

〔Example〕

Hereinafter, with reference to the drawings, a method for manufacturing a tall metal bump according to the gist of a semiconductor device according to an embodiment of the present invention will be further described.

Referring to FIG. 2, in a state where a field insulating film 2 is formed on a semiconductor substrate 1 and a lead electrode 3 is formed on a partial region thereof, a photoresist film 4 is formed to a thickness of about 6 to 7 μm. The photoresist film 4 is removed from the bump formation region into a square shape having a width of about 20 μm by using a lithography method, and an indium film 5 is formed to a thickness of about 5 to 6 μm.

Referring to FIG. 3, the photoresist film 4 is dissolved and removed, and the first layer metal bumps 6 are lifted off.

Subsequently, a photoresist film 7 is formed to a thickness of about 6 to 7 μm, and this photoresist film 7 is formed into a thickness of about 40 μm surrounding the first layer metal bump 6 by using a photolithography method. The indium film 8 is removed from the square region to form an indium film 8 having a thickness of about 5 to 6 μm.

Referring to FIG. 1, the photoresist film 7 is dissolved and removed, and the second-layer metal bumps 9 are lifted off to form a metal bump 10 having a double layer with the first-layer metal bumps 6 and having a high height.

Although some positioning errors are inevitable, the higher the upper layer, the larger the metal bumps are formed.

〔The invention's effect〕

As described above, in the present invention, a columnar metal layer in which the area of the upper layer is larger than the area of the lower layer and the thickness of the upper layer is at least about the same as the thickness of the lower layer is laminated to form a multilayer, Since the metal bumps are constituted by the layers, a semiconductor device having a metal bump having a high height is provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a metal bump according to the gist of the semiconductor device according to the present invention. 2 and 3 are cross-sectional views of the semiconductor device according to one embodiment of the present invention after the main manufacturing steps are completed. DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Field insulating film, 3 ... Lead electrode, 4 ... Photoresist film, 5 ... Indium film, 6 ... First layer metal bump, 7 ... Photoresist film, 8 ... ... Indium film, 9 ... Second layer metal bump, 10
...... Metal bumps.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-150279 (JP, A) JP-A-57-207362 (JP, A) JP-B-51-4633 (JP, B1)

Claims (1)

(57) [Claims] A plurality of semiconductor device chips are connected to a metal binder (1).
0), wherein the metal bump (10) is formed on a base exposed in the first opening by using a first resist pattern having a first opening. Formed on the underlayer and the lower layer (6) exposed in the second opening by using a lower layer (6) formed and a second resist pattern having a second opening larger than the first opening. And an upper layer (9), wherein the area of the upper layer (9) is larger than the area of the lower layer (6).