JPS60167432A - Semiconductor device - Google Patents

Abstract

PURPOSE:To obtain the titled device excellent in moisture resistance by a method wherein an Al layer is formed on the final protection film of a semiconductor element. CONSTITUTION:An Si nitride film 1 is used as the final protection film after passage through a normal wafer process. The formation of an Al film 2 on the final protection film can be carried out either by sputter used in formation of the inner wiring or by vapor deposition. However, since the neighborhood of a bonding pad 4 has the possibility of short with said Al film 2 at the time of wire bonding, this film 2 should be formed at a suitable distance from an edge 5 of a bonding pad window. Now even if water infiltrates into the resin section, the water reacts with the Al on the surface protection film earlier than with the inner Al wiring in the element, and is consumed by forming a water oxide film of Al2O3.3H2O or Al(OH)3; therefore, it is difficult to reach the inner Al wiring. Further, the water that has dissolved the Al of a sacrifice electrode during the course of infiltration contains aluminum ions and its pH varies close to neutral, resulting in the difficulty of corroding the inner Al wiring.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is applied to wiring and electrode materials A in integrated circuits such as IC and LSI.
The present invention relates to a semiconductor device using β.

Conventional configuration and its problems Conventionally, wiring materials for semiconductor devices are electrical and physical.

Ad is the most commonly used in terms of price. This semiconductor element is most often sealed in a resin-sealed package due to the demand for low cost. However, when a semiconductor element is encapsulated in this resin-sealed package, the moisture resistance is extremely low compared to packages with other encapsulation structures such as glass encapsulation or metal encapsulation, and the life of the element is shortened. becomes significantly shorter. This is because the resin part of the encapsulant is porous, so moisture can easily reach the semiconductor element through this bulk, and the difference in thermal expansion coefficient between the resin and the lead (for example, epoxy resin So, 21X1
0'~23X10'/℃, 4.4X for 42 alloy
10-67'C), stress acts on the interface between the resin and the lead due to the difference in shrinkage between the two during sealing, creating gaps and micro-cranks that allow moisture to easily enter. The water that reaches the semiconductor element reacts with Ad in the bonding pad area, causing wire breakage, or passes through the surface protective film, causing the A4 in the internal wiring area to break.
Corrosion problems such as reacting with wires and causing wire breaks are becoming more serious.

OBJECTS OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a semiconductor device with excellent moisture resistance.

Structure of the Invention To summarize, the present invention can be summarized as follows.
The film or Ad plate is broken, and the deposited Al is used as a sacrificial electrode to corrode and dissolve the water that has entered the package, consuming it and corroding the actual bonding pads and internal mull wiring. The present invention provides a semiconductor device that is protected from damage.

DESCRIPTION OF EMBODIMENTS One implementation of the present invention will be described with reference to the drawings. Figure 1 shows Al
FIG. 2 is a cross-sectional view of an NMO8 semiconductor device in which a film is formed by vapor deposition. After going through the usual sea urchin process, a silicon nitride film 1 is used as the final protective film. This is because the silicon nitride film has better moisture resistance than the silica glass film. The Ad film 2 on the final protective film may be formed by sputtering used when forming internal wiring or by vapor deposition. However, since there is a risk of a short circuit with the Ad film 2 near the bonding pad 4 during wire bonding, it should be kept an appropriate distance away from the edge 6 of the bonding pad window.
A7? Film 2 was formed.

By the way, when adhering an Ad plate to the semiconductor element instead of the Al film 2, as shown in FIG. There is a method of adhering the Ad board using. In either method, even if water intrudes into the resin part, the water will react with the material on the surface protective film before the internal A4 wiring in the element, resulting in
A hydroxide film such as No. 3 is formed and consumed, making it difficult to reach the internal Al wiring. Furthermore, during the infiltration, Ad of the sacrificial electrode
The water containing aluminum ions contains aluminum ions, and
The pH changes to near neutrality, making it difficult to corrode the internal Aβ wiring. In addition, in FIGS. 1 and 2, 8 is a Si substrate, 9
1 is a polysilicon electrode, 10 is a silicon oxide film, and 11 is a phosphosilicate glass film, which are ordinary ones.

Effects of the Invention As described above, according to the present invention, the internal A4 wiring is protected by depositing an Al film or an Al plate on the final protective film of the semiconductor element as a sacrificial electrode against A/corrosion. It has significantly improved corrosion resistance and can achieve extremely high reliability even when using a resin-sealed package. Moreover, when an Ad plate is used as the sacrificial electrode, it can serve as a heat sink to quickly dissipate heat generated from the element, and a semiconductor device with low thermal resistance can be realized.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional structural diagram of an NMO8 semiconductor device according to an embodiment of the present invention, and FIG. 2 is a sectional view of a device having the same structure as that in FIG. FIG. 2 is a cross-sectional view of an Ag plate bonded using polyimide resin. 1...SiN, 2--Ad film, total...internal A4 wiring, 4...ponding pad, 6...
・・Bond fetched window etch, 6・・Polyimide resin, 7・・Ag plate, 8・・・・Si
Substrate, 9... polysilicon, 1o... oxide film, 11... phosphosilicate glass film.

Claims (1)

[Claims] (1) A semiconductor device characterized in that an A1 layer is formed on a final protective film of a semiconductor element. (21) The semiconductor device according to claim 1, wherein the A1 layer is an adherend of an Al plate.