JPS597224B2 - flip chip attachment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in flip-chip mounting bodies such as packages to which flip-chip semiconductor chips are mounted.

Hereinafter, we will take as an example a flip-chip mounting body to which a source-grounded gallium arsenide field effect transistor (hereinafter referred to as "GaAsFET") flip chip is mounted. ■ In Figure 1 shown
This will be explained using a vertical cross-sectional view taken along the line -■.

In the figure, 1 is a source-grounded GaAsFET flip chip, 2, 3, and 4 are source protrusion electrodes each provided parallel to the surface of the GaAsFET flip chip 1 at a predetermined interval and having a rectangular surface shape;
They are a drain protrusion electrode and a gate protrusion electrode.

Reference numeral 5 denotes a flip chip mounting body to which the GaAsFET flip chip 1 is mounted, 6 a grounding metal substrate of the flip chip mounting body 5, □ a ceramic substrate made of beryllia or the like attached to the surface of the grounding metal substrate 6, 8 , 9 and 10 are formed on the surface of the ceramic substrate 7 at positions corresponding to the source protrusion electrode 2, the drain protrusion electrode 3, and the gate protrusion electrode 4, respectively.
, and 4 are a source bonding pad, a drain bonding pad, and a gate bonding pad made of a rectangular metal film such as a thin film or a thick film, which are simultaneously bonded.

Note that both ends of the source bonding pad 8 are connected to both end faces of the grounding metal substrate 6 via both end faces of the ceramic substrate 7 by thin metal films. However, especially in the flip chip 1 for high power and high frequency applications, the source projecting electrode 2 needs to be elongated in the longitudinal direction, so that the source bonding pad 8 is also elongated in the form of a rectangle.

For this reason, So. - from the base protruding electrode 2 to the grounding metal substrate 6
The electrical length up to L becomes longer, and the source parasitic inductance L
As s increases, the maximum available power gain decreases. Furthermore, as shown in the perspective view of FIG. 3, even when a plurality of flip chips 1 are mounted in parallel on the flip chip mounting body 5 to obtain high output, the source protrusion electrode 2 of each flip chip 1 is connected to the grounding metal substrate 5. Since the electrical length between the flip chips 1 and 1 is not uniform and differs for each flip chip 1, the output impedance between the flip chips 1 varies, making it impossible to efficiently combine the respective outputs. It was hot too. The present invention has been made in view of the above-mentioned drawbacks, and includes a semiconductor chip having a flip-chip structure. It is an object of the present invention to provide a flip chip mounting body that can improve the characteristics of the semiconductor chip in the microwave frequency region by providing a grounding metal film that is grounded.

FIG. 4 is a sectional view showing an embodiment of the flip-chip mounting body of the present invention in which a source-grounded GaAsFET flip-chip is mounted. In the figure, 7a denotes a source bonding pad 8 made of a rectangular metal film to which the source protrusion electrode 2 having a rectangular surface shape is bonded and a gate bonding pad 10 made of a metal film to which the gate protrusion electrode 4 is bonded. a first ceramic substrate 7b having side surfaces parallel to the longitudinal ends of the source bonding pads 8;
11 is a second ceramic substrate having the same thickness as the first ceramic substrate 7a and has a drain bonding pad 10 made of a metal film on its surface to which the drain projection electrode 3 is bonded; and 11 is a first ceramic substrate. 7a
This is a source grounding metal film that is provided on the side surface in the longitudinal direction and connects the film end of the source bonding pad 8 along this side surface and the grounding metal substrate 6.

Note that the source grounding metal film 11 and the side surface of the second ceramic substrate 7b are in contact with each other, and the surfaces of each of the source bonding pad 8, drain bonding pad 9, and gate bonding pad 10 are approximately First and second ceramic substrates 7a and 7b are attached to the surface of the grounding metal substrate 6 so as to be on the same plane. In the flip chip mounting body 5 of this embodiment configured in this way, the source bonding pad 8
Since the film end in the longitudinal direction is connected to the grounding metal substrate 6 by the source grounding metal film 11, even a source projecting electrode with a long longitudinal length such as a flip chip for high power and high frequency can be used. Since the electrical length between this and the grounding metal substrate 8 can be significantly shortened, the source parasitic inductance Ls of the flip chip can be significantly reduced.

According to the results of experiments conducted by the inventors, it is possible to reduce the source parasitic inductance Ls of the flip chip in the microwave frequency region by about 1 nH or more compared to that of the conventional example shown in FIG. Therefore, the maximum available power gain could be improved by about 2 dB or more. In addition, as shown in FIG. 3, even in the case of a long rectangular source bonding pad in which the source protruding electrodes of a plurality of flip chips are bonded in parallel in the longitudinal direction, the film end in the longitudinal direction is connected to a short source. Since the flip chips are grounded by the grounding metal film, the source parasitic inductance Ls of each flip chip is uniform and extremely small, so there is no variation in input/output impedance between the flip chips, and each output can be efficiently output. Can be easily synthesized. Furthermore, since the thickness of the source grounding metal film is so thin that it can be virtually ignored, the dimensions of the flip chip can be made comparable to those of conventional flip chips. In the above embodiment, the source grounding metal film was provided only on the side surface of the first ceramic substrate, but it may be provided on both the side surface of the first ceramic substrate and the side surface of the second ceramic substrate in contact with it. You can also do this.

Further, in the above embodiments, the case where the source is grounded is described, but it is also possible to apply to other cases where the drain is grounded or the gate is grounded.

Although the flip-chip mounting body for mounting a GaAsFET flip chip has been described, the present invention is not limited to this, and the present invention is applicable to a flip-chip mounting body for mounting semiconductor chips having a flip-chip structure such as microwave power FETs, MOS transistors, and thin film transistors. It can also be applied to As explained in detail above,
According to the present invention, a grounding metal film is provided on one longitudinal edge of a bonding pad to which an elongated protruding electrode to be grounded of a semiconductor chip having a flip-chip structure is connected by bonding. Therefore, even when the bonding pad has a long longitudinal length, the electrical length for grounding it can be significantly shortened.

Therefore, the parasitic inductance Ls of the protruding electrode of the semiconductor chip bonded to the bonding pad can be significantly reduced. Then,
It is possible to provide a flip chip mounting body that can improve the characteristics of the semiconductor chip in the microwave frequency region.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a conventional flip-chip mounting body in which a source-grounded GaAsFET flip-chip is mounted, FIG. 2 is a longitudinal cross-sectional view taken along the - line in FIG. 1, and FIG. FIG. 4 is a perspective view showing a conventional flip-chip mounting body equipped with a GaAsFET flip-chip;
The figure is a sectional view showing an embodiment of the flip-chip mounting body of the present invention, in which a source-grounded GaAsFET flip-chip is mounted. In the figure, 1 is a GaAsFET flip chip (semiconductor chip with flip-chip configuration), 2 is a source protrusion electrode (first protrusion electrode), 3 is a drain protrusion electrode (third protrusion electrode), 4 is a gate, protrusion electrode ( 6 is a grounding metal substrate, 7a and 7b are first and second ceramic substrates, 8 is a source bonding pad (first bonding pad), and 9 is a drain bonding pad (first bonding pad). 3 bonding pad), 10 gate bonding pad (second bonding pad),
11 is a metal film for grounding.

Claims (1)

[Claims] 1. The above-mentioned first semiconductor chip having a flip-chip structure having a first elongated protruding electrode to be grounded and second and third protruding electrodes sandwiching the first protruding electrode and not being grounded.
and a first bonding pad made of a metal film to which a second projecting electrode is bonded and connected, respectively, are provided on the surface thereof, and the first bonding pad has a side surface parallel to an edge along the longitudinal direction of the first bonding pad. and a second ceramic substrate provided with a third bonding pad made of a metal film on the surface to which the third projecting electrode is bonded are attached to the grounding metal substrate, and the second ceramic substrate is attached to the grounding metal substrate. A flip-chip mounting body comprising a grounding metal film on the side surface of the ceramic substrate that connects the first bonding pad to the grounding metal substrate over the entire length of the first bonding pad in the longitudinal direction.