JP2633128B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device such as a gun diode used in a millimeter wave band, and more particularly to a package and a wiring structure.

[0002]

2. Description of the Related Art In a semiconductor device, a package is indispensable for protection and reliability improvement of a semiconductor chip, and a two-terminal type semiconductor device used in a microwave band or higher, particularly a gun having a large heat generation density. In the diode, a pill type package excellent in heat dissipation is used as a package.

FIG. 3 shows a conventional method of packaging a gun diode. Reference numeral 1 denotes a package body made of Cu, and a diamond heat sink 2 as a pedestal portion is attached to a central portion of the package body. Reference numeral 3 denotes an alumina ceramic ring, one end face of which is fixed to the package body 1 (FIG. 3A). Gun diode chip 4 is a plated heat sink
It is manufactured in a mesa shape with a hole, and is die-bonded to the pedestal portion 2 by thermocompression bonding or soldering at a portion of the plated heat sink (FIG. 2B). The gun diode element has upper and lower electrodes formed thereon, and the pedestal 2 also serves as a lower electrode. On the other hand, the upper electrode of the Gunn diode element is connected to the metal coating on the ceramic ring 3 via the gold ribbon 5 (FIG. 3C). Finally,
The upper part of the ceramic ring 3 is sealed with a lid 6 made of gold-plated Cu, and this serves as an upper electrode (FIG. 3D).

In such a Gunn diode, in order to improve the high-frequency characteristics, it is necessary to reduce the inductance L and the capacitance C of wiring inside and outside the package. In particular, even in the case of millimeter waves, the U-band (40 to 60 GHz) is required. In the high frequency band described above, even small values of L and C greatly affect the characteristics. For this reason, various measures have been taken such as making the lead wires in the package a wide ribbon or connecting a plurality of the ribbons in parallel (cross, hexa-ribbon connection, etc.).

[0005]

However, in recent years, higher frequency bands such as E-band (60 to 90 GHz),
As millimeter-wave devices operating in the W-band (75-110 GHz) or higher frequency bands are developed,
It has become clear that the conventional packaging method cannot sufficiently bring out the inherent performance of the element even if the shape of the lead wire is changed. For this reason, attempts have been made to improve the high-frequency performance of a package using a quartz ring having a low dielectric constant instead of an alumina ring generally used as a package insulator. However, quartz has low compressive strength and tensile strength compared to alumina, and is fragile, so there is a problem that cracks are easily formed when brazing to a Cu package body.

Accordingly, the present invention provides a semiconductor device capable of sufficiently reducing the inductance and capacitance of the wiring even in the millimeter-wave band of 60 GHz or more, having excellent high-frequency characteristics, and obtaining high reliability and sufficient heat dissipation. The purpose is to do.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a heat radiator, a semiconductor element chip having one main surface fixed to the heat radiator, and a hollow portion surrounding the semiconductor element chip. An insulator having one end face of the hollow portion in contact with the heat radiator and the other end face being separated from the heat radiator by a predetermined distance from another main face of the semiconductor device chip; and another end face of the insulator. A metal foil for connecting the other main surface of the semiconductor element chip, and a lid which is alloyed with the metal foil and is attached to another end surface of the insulator to seal the hollow portion, wherein the predetermined distance is The gist is that the thickness is not less than 3 times and not more than 10 times the thickness of the metal foil.

Preferably, the predetermined distance is 30 to 100 μm
It is said. The semiconductor element chip has electrodes on both main surfaces,
In particular, a Gunn diode is applied. The radiator is made of metal or the like, and is connected to one electrode of the semiconductor element chip. The insulator is formed in a cylindrical shape. The metal foil is made of Au and has a thickness of 5 to 20 μm. The lid is made of metal, A
It is alloyed with a eutectic alloy of Au such as u-Sn and attached to the other end face of the insulator.

[0009]

Since one main surface of the semiconductor element chip is fixed to the heat radiator, sufficient heat radiation can be obtained. Since the height difference between the other main surface of the semiconductor element chip and the other end surface of the insulator is a predetermined distance of 3 to 10 times the thickness of the metal foil, the length of the metal foil connecting the two is Is shortened, the inductance is reduced, and the high-frequency characteristics are improved. Also,
Since the lid is attached to the end face of the insulator by alloying, high reliability can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. This embodiment is applied to an InP gun diode. That is, in a millimeter-wave semiconductor device typified by a Gunn diode, a structure necessary for reducing an inductance component accompanying a package is examined and defined.

FIG. 1A is an enlarged sectional view of a portion A in FIG.

In FIG. 1, components that are the same as or equivalent to those in FIG. 3 are denoted by the same reference numerals as those described above, and redundant description is omitted.

In FIG. 1, one end face of an alumina ceramic ring 7 as an insulator is
It is fixed to. Gunn diode chip 4 as a semiconductor element chip has a diameter of 60 μm and has electrodes on both upper and lower surfaces,
It is manufactured in a mesa type with a plated heat sink. The lower surface of the gun diode chip 4 is die-bonded to the diamond heat sink 2 by thermocompression bonding or soldering at a plated heat sink. The upper surface of the gun diode chip 4 is defined to be lower by 50 μm to 100 μm than the upper surface of the ceramic ring 7. The connection between the upper electrode of the Gunn diode chip 4 and the metal coating on the ceramic ring 7 is W
-Thickness of 10 to 15 for band (75 to 110 GHz)
A gold ribbon 8 made of a metal foil having a thickness of about 100 μm and a width of about 100 μm is used. On the upper part of the ceramic ring 7, a gold-plated lid 6 made of Au—Sn is sandwiched by a gold ribbon 8.
Eutectic alloy.

Next, using a Gunn diode designed to oscillate at 94 GHz, a height difference Δ between the upper surface of the Gunn diode chip 4 and the upper surface of the ceramic ring 7 is set to 300.
Samples packaged as μm, 200 μm, 100 μm, and 50 μm were prepared, and an oscillation experiment was performed. As a result, it was recognized that the smaller the height difference Δ, the higher the high-frequency characteristics.

FIG. 2 shows the band characteristics of each sample in which the height difference Δ was 300 μm (characteristic line a), 200 μm (characteristic line b) and 100 μm (characteristic line c). The mount and the resonator have the same conditions. The height difference Δ of the comparative example is 300 μm
In the sample of No. 5, the oscillation frequency was 85-90 GHz, whereas in the sample of the present example in which the height difference was 100 μm, the oscillation frequency was 95-100 GHz, and the output was 1.3 times or more of the comparative example. However, when the height difference Δ is less than 50 μm, the thickness of the gold ribbon 8 is 10 to 15 μm and the deflection 1
Since the gap with the lid 6 is reduced by 0 to 20 μm,
The eutectic solder (Au-Sn) used to seal the lid 6 flows into the gold ribbon 8 side, and the quality of the gold ribbon 8 becomes hard and gives stress to the gun diode chip 4 such as pulling and displacement. May be damaged.

The above result is one example and lower V-ba
Similarly, in the case of nd and U-band, the improvement of the oscillation output on the high band side was recognized in the case of the present example as compared with the comparative example.

Accordingly, from the above results, the height difference Δ is 100
μm or less and 30 μm or more, that is, the height difference Δ
It has been found that the thickness is preferably in the range of 3 to 10 times the thickness of the gold ribbon 8.

[0018]

As described above, according to the present invention,
Since the height difference between the other main surface of the semiconductor element chip and the other end surface of the insulator is set to 3 times or more and 10 times or less of the thickness of the metal foil,
The length of the metal foil is shortened, the inductance is reduced, and excellent high-frequency characteristics can be obtained even in the millimeter wave band of 60 GHz or more. Since one main surface of the semiconductor element chip is fixed to the heat radiator, sufficient heat radiation can be obtained. Further, since the lid is attached to the end face of the insulator by alloying, high reliability can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view and the like showing an embodiment of a semiconductor device according to the present invention.

FIG. 2 is a diagram illustrating an oscillation frequency-output characteristic of the present embodiment together with a comparative example.

FIG. 3 is a diagram illustrating a conventional gun diode packaging method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Package main body 2 Diamond heat sink which comprises a radiator with a package main body 4 Gun diode chip (semiconductor element chip) 6 Lid 7 Ceramic ring (insulator) 8 Gold ribbon (metal foil)

Claims (1)

(57) [Claims] 1. A heat radiator, a semiconductor element chip having one main surface fixed to the heat radiator, and a hollow portion surrounding the semiconductor element chip, one end face of the hollow portion being in contact with the heat radiator. An insulator whose other end face is separated from the radiator by a predetermined distance from the other main surface of the semiconductor element chip, and a metal foil that connects the other end face of the insulator to another main surface of the semiconductor element chip. A lid that is alloyed with the metal foil and attached to the other end surface of the insulator to seal the hollow portion, wherein the predetermined distance is not less than 3 times and not more than 10 times the thickness of the metal foil. Characteristic semiconductor device.