JP3070705B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly, to a surface-mounted semiconductor device.

2. Description of the Related Art A conventional surface-mount type semiconductor device, for example, a Schottky barrier diode has a structure as shown in FIG. Referring to FIG. 4, in order to take out the cathode electrode 5a on the semiconductor substrate layer 1, it is necessary to previously diffuse the impurities into the high-resistance active layers 2a and 2b to form the low-resistance layer 9. Was. The low-resistance layer 9 is not essentially essential, but is a medium for extracting the cathode electrode. When the semiconductor device is mounted on a circuit board, it is necessary to mold the entire surface of the semiconductor device with the protective resin 8. In such a conventional surface mount type semiconductor device, a semiconductor manufacturing process and a protective resin sealing process are complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor device having a sectional structure in which a connection electrode is formed directly on a substrate layer below an active layer in a surface mount type semiconductor device. It is an object to simplify the sealing step.

In order to solve the above-mentioned problems, the present invention solves such a problem by removing the active layer by etching to remove the active layer directly from the substrate layer, and by using a metal electrode around the periphery. Connect to the surrounding cathode electrode. Further, the upper and side surfaces of the peripheral electrode are covered with a resin.

FIG. 1 is a view showing a manufacturing process of a Schottky barrier diode according to an embodiment of the present invention. Fig. 1 (a)
As shown in FIG. 1, an active layer 2 is first formed on a substrate layer 1, and an oxide film 3 is formed on the uppermost layer. Then, guard rings 21a and 21b are formed on the upper surface of the active layer 2.
Next, as shown in FIG. 1 (b), a region for forming a semiconductor device is left on the epitaxial wafer of the active layer 2,
The active layer 2 in the other area is removed by etching until the active layer 2 reaches the upper surface of the substrate layer 1, leaving two element areas of the active layers 2a and 2b. Next, as shown in FIG. 1 (c), metal electrodes 5a, 5b, 5c are formed on the partially exposed surface of the substrate layer 1. These metal electrodes 5a, 5b, 5c are connected to the active layer 2 as shown in FIG.
It is formed so as to surround an element region formed on each of a and 2b, and serves as a cathode electrode and a cathode peripheral electrode. The central portions of the oxide films 3a and 3b are removed, and metal electrodes 4a and 4b are formed on the active layers 2a and 2b, respectively, to form anode electrodes. Next, as shown in Fig. 1 (d),
Using a photosensitive thermoplastic resin such as polyimide, the metal electrodes 4a, 4b and the metal electrode 5a are covered by a photolithography process. The coating protective resin 8a is composed of the substrate layer 1 and the metal electrode 5b.
, The active layer 2a, the oxide film 3a, the metal electrode 4a, and their mutual interface. The same applies to the protective resins 8b, 8c, 8d. Next, as shown in FIG. 1 (e), bump electrodes 6a, 6b, 7 are formed on the metal electrodes 4a, 4b and 5a by a soldering printing process or a silver plating process, respectively. The Schottky barrier diode is completed as described above, and these processes are simultaneously formed on a single wafer by connecting a large number of each in the vertical and horizontal directions. After the above steps are completed, the edge of each semiconductor device is cut by dicing. The completed drawing is shown in FIG. FIG. 2 (f) is an electric circuit diagram, FIG. 2 (g) is a completed cross-sectional view, and FIG. 2 (h) is a half-cut sketch, in which protective resins 8a, 8b, 8c , 8d and the bump electrodes 6a, 6b, 7 are omitted. In the Schottky barrier diode thus formed, the cathode electrode formed of the metal electrode 5a can be easily formed on the surface of the substrate layer 1 by etching the active layer 2. After the etching around the element region, which is performed simultaneously with the etching, the metal electrodes 5b and 5c are formed on the surface of the substrate layer 1. These metal electrodes 5b and 5c function as cathode peripheral electrodes, and current concentration in the lateral direction (the left-right direction in FIG. 1) is reduced. Further, there is no active layer at the periphery of the element, and the active layers 2a and 2b are located inside the substrate layer 1, and the portion is covered with the protective resin 8a, 8b, 8c, 8c, etc. In addition, it is not necessary to perform a resin sealing step over the entire surface as in the conventional case, and the chip can be directly mounted after dicing (dicing step). Although the embodiment of the present invention has been described with reference to a Schottky barrier diode, the present invention
The present invention can be applied to a pn junction diode, a transistor, and the like. FIG. 3 is a partial view of an embodiment in which the element region is a pn junction. A p-type semiconductor is formed in the active layer 2a by diffusion, and a metal electrode 4a is formed thereon. Other structures are the same as those shown in FIGS.

According to the present invention, as described above, a metal electrode is taken out to the surface of a semiconductor substrate layer by etching into an active layer to form a cathode and a cathode peripheral electrode. In addition, since the structure having the protective resin covering the active layer is adopted, it is easy to take out the electrode to the substrate surface, and it is possible to reduce the current concentration in the lateral direction. Further, since a resin sealing step after chip formation is not required, both steps and materials are economical. As a result, the thickness can be reduced, and the mounting density can be improved.

[Brief description of the drawings]

FIG. 1 is a view showing a process of a Schottky barrier diode according to the present invention.

FIG. 2 is a structural diagram of a Schottky barrier diode according to the present invention.

FIG. 3 is a partial view of the structure of a diode according to the present invention.

FIG. 4 is a diagram showing an example of the structure of a conventional Schottky barrier diode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate layer 2, 2a, 2b ... Active layer 21a, 21b ... Guard ring 22 ... P layer 3, 3a, 3b ... Oxide film 4a, 4b ... Electrode metal (anode) 5a, 5b, 5c ... Electrode metal (cathode) 6a, 6b… Bump electrode (anode) 7… Bump electrode (cathode) 8a, 8b, 8c, 8d… Protective resin

Claims (2)

(57) [Claims] In a surface mount type semiconductor device, an active layer is partially removed except for an element region by etching, an electrode metal is directly formed on a substrate layer below the removed active layer, and an electrode metal is formed on the electrode metal. A semiconductor device comprising a bump electrode. 2. The semiconductor device according to claim 1, wherein an upper surface excluding said bump electrodes is covered with a thermoplastic resin.