JPS6216548B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a heat dissipation structure for a semiconductor device.

When dealing with semiconductor devices such as Gunn diodes and impact diodes, which have a high power density, the heat generated in the operating parts must be promptly released to the outside of the device to protect the device from thermal destruction. Plated heat sink (hereinafter referred to as Plated Heat Sink) is one of the heat dissipation structures to efficiently transfer the heat generated in the operating part to the outside of the element.
PHS (written as PHS) is in practical use.

Taking the Gunn diode as an example of a practical PHS, its manufacturing method and structure are shown in Figures 1a-e.
Shown below. Low resistivity n-type gallium arsenide (hereinafter
First, a wafer is prepared on which n-type GaAs 2 with a high resistivity to serve as an active layer and n-type GaAs 3 with a low resistivity to form an ohmic electrode are epitaxially grown on a substrate 1 of GaAs (denoted as GaAs) (see Fig. 1). a). Metals such as gold and germanium are deposited on the surfaces of the GaAs substrate 1 and the GaAs layer 3, which have low resistivity, and are alloyed to form electrodes 4 and 5 with good ohmic properties (FIG. 1b). On top of the electrode 5,
Gold is grown thickly by electrolytic plating to form PHS6 (Figure 1c). Semiconductor crystal parts 1, 2, and 3 are removed by chemical etching or the like, leaving only predetermined areas (Fig. 1 d), and finally, the PHS part 6 is cut to complete individual devices (Fig. 1 e). .

The conventional PHS manufacturing method described above has two major drawbacks. One is that the stress generated by PHS formation becomes extremely large when PHS is formed continuously over the entire wafer as shown in Figure 1c, which may cause defects in the semiconductor crystal. It is expected that the number of minute defects is increasing. Furthermore, as shown in Figure 1(d), another drawback is that in the conventional PHS manufacturing method, elements are separated by etching, so a very large portion of the semiconductor crystal that could originally become an element must be removed. Unavoidably, the yield of the device inevitably deteriorates.

The present invention aims to eliminate the drawbacks of the conventional PHS manufacturing method described above.

That is, according to the present invention, a manufacturing method is obtained in which the PHS is attached by electrolytic plating after element separation.

Hereinafter, one embodiment of the present invention will be described with reference to FIG. 2, taking the case of a Gunn diode as an example, based on FIG. 1. In the manufacturing method according to an embodiment of the present invention, the steps shown in FIGS. 1a to 1b are the same as those in the conventional method.
The wafer fabricated up to FIG. 1b is cut into a predetermined size by scribing with a diamond scriber, etc., and the cut pieces 11 are arranged on the conductive film 12 at appropriate intervals (FIG. 2a). As a simpler method for arranging the cut pieces 11, it is also possible to cut the wafer by placing it in close contact with a conductive film with good stretchability, and then stretch the conductive film appropriately. In either case, the surface opposite to the surface on which the PHS is formed (the surface of the electrode 4) is brought into close contact with the conductive film 12. The conductive film 12 is formed by forming the PHS 13 on the cut piece 11 by electrolytic plating, using the conductive film 12 as one electrode for plating.
Predetermined Gunn diode elements are arranged on top (FIG. 2b), and when used, these elements can be peeled off from the conductive film 12.

As is clear from the above description, according to the present invention, the stress on the semiconductor crystal caused by PHS can be considered in terms of the size of each element and can be ignored in practical terms. Moreover, the device yield also increases dramatically.

Although the Gunn diode has been described above as an example of the present invention, it is obvious that the present invention can be easily applied to other semiconductor devices.

[Brief explanation of the drawing]

1A to 1E are cross-sectional views showing the manufacturing process and structure of a Gunn diode according to a conventional PHS manufacturing method, and FIGS. 2A to 2B are cross-sectional views showing a PHS according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing the manufacturing process and structure of a Gunn diode having a structure. 1, 2, 3... n-type GaAs crystal, 4, 5... electrode, 6, 13... PHS, 12... conductive film.

Claims (1)

[Claims] 1. A plurality of semiconductor elements cut and separated into individual pieces are supported by a conductive film in a state where the intervals between them are widened, and then the conductive film is used as a current conduction path to serve as a heat sink on each semiconductor element. A method for manufacturing a semiconductor device characterized by forming metal by plating.