JPS594853B2 - semiconductor equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a structure that can prevent corrosion of electrodes in a semiconductor device.

In high-frequency transistors, in order to reduce the capacitance between the electrode and the semiconductor and improve its characteristics, it is necessary to minimize the contact area with the semiconductor and the area other than the contact area with the wire. The aluminum layer, which is the electrode between the contacts, is thinner.

Additionally, the electrodes of semiconductor devices are naturally sealed to prevent moisture from entering, but during long-term use, moisture can enter and corrode the 10-electrode portion made of aluminum. In many cases, as mentioned above, if the aluminum electrode is formed to be thin in areas other than the contact area, that area will easily break due to corrosion. FIG. 1 is a plan view showing an example of an electrode part of a high-frequency transistor. Reference numerals 1 and 2 are hand-shaped aluminum electrodes, and these electrodes have a bonding pad part 3 and a bonding pad part 3, respectively.
4 is provided, and bonding wires 5 and 6 are connected to this bonding pad portion.

As mentioned above, the cross-sectional area of the parts other than the contact part between the electrode and the semiconductor and the contact part with the bonding wire, that is, the parts A and B in FIG. 1, is extremely small because the width is as narrow as possible. Therefore, if moisture enters this part, it will corrode and break in a short period of time25. As the electrode protective film, C
A 5102 film is formed on the electrode by the VD method, but as is well known, this film has the characteristics of being hard and brittle, so it is prone to cracking and peeling due to thermal strain, so it is not necessary to use it as a protective film. It has enough functions, but it doesn't.

Therefore, the inventor of the present invention attempted to provide a polyimide resin film, which has good electrical insulation properties, is hard to crack, and is thermally stable, in place of the CVD film, but the following problems occurred.

That is, even if polyimide resin was used, the resin film had to be opened at the bonding pad area, and eventually moisture entered from this area, causing corrosion of the electrode section.
The present invention has been achieved in order to eliminate the drawbacks of the prior art, and aims to reduce the stray capacitance between the substrate and the conductor layer, sufficiently protect the conductor layer made of aluminum, and prevent corrosion. The purpose of this invention is to prevent the conductor layer from being disconnected and electrical connection with the semiconductor element region formed within the semiconductor substrate being cut off.

The configuration of the present invention for achieving such an object includes a semiconductor substrate having a semiconductor region formed therein, a portion connected to the semiconductor region, and another portion extending to an insulating film on the semiconductor substrate and substantially flat. a first conductor layer forming a contact portion; a protective film made of polyimide resin covering the first conductor layer; A second conductor layer made of aluminum for wire connection and extending over the protective film so as to cover the opening, and bonded to the second conductor layer on the substantially flat contact portion. A semiconductor device characterized by comprising a wire.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a cross-sectional view illustrating the main parts of a semiconductor device manufactured according to the present invention, in which 11 is a semiconductor substrate, 11a is a collector part, 11b is a base part, and 11c is an emitter part. A protective film (SiO2 film) 21 is formed on the upper surface of this semiconductor substrate 11 except for the electrode lead-out portion. 12,1
Reference numeral 3 designates a first stage electrode, at one end of which a contact portion with the semiconductor substrate is formed, and at the other end contact portions 14 and 15 with the second stage electrode are formed.

Reference numeral 16 denotes a protective film made of polyimide resin, which is provided over the entire surface except for the openings through which the contact parts 14 and 15 are seen.

Reference numerals 17 and 18 are second-stage electrodes, which have a slightly concave shape in the center, and the contact portion 14 below the center portion.
, 15.

19 and 20 are bonding wires, which are connected to the second stage electrode 1.
7 and 18.

As is clear from FIG. 2, the contact portions 14 and 15 are located on a hard SiO2 film and have a flat surface. Therefore, the bonding butt portions 17a and 18a are securely contacted with the contact portions 14 and 15, and since the wire is bonded to the bonding butt portion on the flat surface of the contact portion, there is no contact with the wire. The electrical connection with the first stage electrode is reliable.

The structure is formed by an etching method using photoresist, a CVD method,
Although it is manufactured using techniques such as metal vapor deposition, the present invention does not impose any limitations on these manufacturing techniques, but just to be sure, the manufacturing process is exemplified as follows.

(a) The first stage electrodes 12 and 13 are configured as shown in FIG.

At this time, since the bonding butt portion of the wire is extended upward, the area of the contact portions 14, 15 is made much smaller than that of the conventional device. (Semiconductor substrate 11
The process of processing the protective film 21 and the process of providing the protective film 21 are the same as those of the conventional method.

) (b) A protective film 1S made of polyimide resin is formed entirely on the surfaces of the first stage electrodes 12, 13 and the protective film 21. At this time, the thickness of the protective film 16 is adjusted as necessary to reduce the stray capacitance of the electrode. (c) A through hole is formed by opening a portion of the protective film 16 so that the contact portions 14 and 15 can be seen.

(This may be carried out simultaneously with the above-mentioned opening process.)
form.

At this time, it is preferable that the bonding centers of the bonding wires 19 and 20 be located at the opening. FIG. 3 shows the contact portion 1 of the first stage electrodes 12 and 13.
4, 15, and second stage electrodes 17, 1 provided thereon.
8 and bonding wires 19 and 20, which are integrally connected.

As can be seen from FIG. 3, the portion A extending from the contact portions 14, 15 is thin foil-shaped, but the second stage electrodes 17, 18 connected to the contact portions 14, 15 are quite large. can be made into something. In the semiconductor device configured as described above, when the second electrodes 17 and 18 are corroded, the corrosion starts from the C and D parts, and then progresses to the E part, but the corrosion does not occur in the normal state to this E part. In this case, it is clear that the corrosion will not progress and will stop midway, so that it will never progress to part A in the end.

As described above, the present invention provides the protective film 16 made of resin such as polyimide on the upper surfaces of the first stage electrodes 12, 13, etc.
A protective film 16 above the contact portions 14 and 15 of this electrode
is opened, and second stage electrodes 17 and 18 are provided in this opening,
The structure is characterized in that the bonding wires 19 and 20 are connected to the electrodes, and the following effects are achieved.

(B) As shown in the figure, the second stage electrodes 17 and 18 act as plugs for the opening of the protective film 16, providing good moisture-proofing properties and preventing disconnection even if the first aluminum electrode underneath is small. can. (b) The second stage electrodes 17 and 18 can be made considerably large without deteriorating the function of the semiconductor device, making bonding work easier, and the openings can be formed by the second stage electrodes and bonding wires 19 and 20. Since it is covered, there is no passage of moisture to the first stage electrode.

Further, since the first stage electrode and the second stage electrode are thick and connected in a columnar manner, there is little chance of disconnection. Furthermore, if the second
Even if the exposed part of the stage electrode is corroded, the part of the second stage electrode covered by the wires 19 and 20 is not corroded and the wires and the first stage electrode are not corroded.
Electrical connection with the stage electrodes is completely maintained. (c) Part where a wire breakage occurred in a conventional semiconductor device (part A in Figure 1)
, B) are completely coated with a protective film made of resin, so even if this portion is small, disconnection will not occur.

(d) Even if the second stage electrode is made larger, if the protective film made of resin is made thicker, an increase in stray capacitance can be avoided, and the aluminum electrode that is the first stage electrode can be made smaller. The capacitance between this electrode and the semiconductor substrate can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of an electrode of a high-frequency transistor, FIG. 2 is a sectional view of a main part of a semiconductor device showing an embodiment of the present invention, and FIG. 3 is an explanatory diagram showing the relationship between the electrode and bonding wire. It is. 1, 2... Aluminum electrode, 3, 4...
... bonding butt part, 5, 6 ... bonding wire, 11 ... semiconductor substrate, 11a
...Collector part, 11b...Base part, 11c...Emitter part, 12, 13...
...First stage electrode, 14, 15...Contact part, 16...Protective film, 17,18...Second stage electrode, 19,20... ...Bonding wire, 21...Protective film.

Claims (1)

[Claims] 1. A semiconductor substrate on which a semiconductor region is formed, and a first conductor layer having a portion connected to the semiconductor region and the other portion extending to an insulating film on the semiconductor substrate to form a substantially flat contact portion. , a protective film made of polyimide resin that covers the first conductor layer, and a protective film that is connected to the contact portion through an opening provided in the protective film, and that is placed on the protective film so as to cover the opening. A semiconductor device comprising: a second conductor layer made of aluminum for connecting an extending wire; and a wire bonded to the second conductor layer on the substantially flat contact portion.