JPS63192240A - Semiconductor device - Google Patents

Abstract

PURPOSE:To inhibit the generation of cracks at the end section of the interface of an SiN film and an SiO2 film, and to prevent the intrusion of water by applying an elastically deformed film just under the end section of an overcoat film consisting of SiN. CONSTITUTION:An elastically deformed film 10 is applied between an silicon nitride (SiN) film 7 and an SiO2 film 4. When a PCT test is conducted at that time, large stress is applied to the surface of a chip by the swelling of a molding resin surrounding the periphery of the semiconductor chip. Consequently, large stress is applied onto the interface of the SiN film 7 and the SiO2 film 4 having the large difference of thermal expansion coefficients, but stress is relaxed because the Al film 10 formed on the interface is deformed elastically, thus generating no crack. Accordingly, the intrusion of water from the interface section is also prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a semiconductor device using an overcoat film, and particularly to a semiconductor device with good moisture resistance.

[Conventional technology]

BACKGROUND ART Glass coat films (Si02 films) and silicon nitride films (SiN films) have conventionally been used as semiconductor chip surface protective films (so-called overcoat films). In particular, glass coat 1m (si) has been used for a long time to improve the moisture resistance of devices.

Since the SiN film has a denser composition, has a stronger blocking effect against impurities, and is not hygroscopic than the SiN film (2), and is effective, it is beginning to be used in many semiconductor devices.

FIG. 2 is a sectional view showing an example of a conventional semiconductor device in which an SiN overcoat film is applied to an NPN transistor.

In this figure, 1 is the collector of the NPN) transistor,
2 is a base, 3 is an emitter, 4 is an oxide film, 5 is a base electrode, 6 is an emitter electrode, 7 is a silicon nitride film,
8 is a base bonding pad, and 9 is an emitter bonding pad. The semiconductor device configured in this way protects the chip surface by covering the parts other than the emitter, pace pounding pad 9.8 and scribe street with 5iNIQ7, which is dense and has no moisture absorption, and is particularly resistant to moisture. This is what we are trying to achieve.

However, as a method for evaluating the moisture resistance of such conventional elements, the general pre-shank car test (PC
When the molding resin surrounding the semiconductor chip (T test) is performed, the molding resin surrounding the semiconductor chip swells (swells) due to moisture intrusion into the resin and exposure to high temperatures, which places a large stress on the chip surface.

Then, the SiN film 7 is denser and harder than the oxide film (Sin2 film) 4, and has a smaller thermal expansion coefficient.
Since the difference in thermal expansion coefficient with the i02 film 4 is large, a large stress is applied to the interface between the SiN film 7 and the 5in2 film 4, as shown in FIG.
A crank 11 is generated slightly from the edge of the interface. Moisture enters into the crank 11, and this intrusion of water causes the crank 11 to further expand, and then the SiN film 7 itself becomes racked, causing problems such as an increase in leakage current of the element.

[Problem that the invention seeks to solve]

Conventional semiconductor devices are configured as described above, so
Although 5iNIQ originally has a strong passivation effect in PCT tests and other reliability tests, cranks occur at the edge of the interface between the SiN film and the 5i02 film, causing the SiN film to The problem was that it was not possible to fully utilize the abilities of the people.

This invention was made to solve this problem, and consists of a SiN film and 5iO2I15! An object of the present invention is to obtain a semiconductor device which can suppress the occurrence of cracks at the edge of the interface and can prevent water from entering.

[Means for solving problems]

The semiconductor device according to the present invention has a plastically deformable film deposited directly under the edge of an overcoat film made of SiN.

[Effect]

In this invention, since a plastically deformable film is attached between the 5iNIQ and 5i02 films, stress caused by misalignment due to the difference in thermal expansion coefficient between the SiN film and the 5io2 film is alleviated, and the crankshaft at the edge of the interface is The generation of water is prevented, and the intrusion of water is also prevented.

〔Example〕

FIG. 1 shows a cross-sectional view of a semiconductor device according to an embodiment of the present invention, and this embodiment will be explained below using this figure.

In Fig. 1, the element is the same NPN transistor as the conventional example, and ▪ is the collector, 2 is the base, 3 is the emitter, 4 is the SiO2 film, 5 is the base electrode, 6 is the emitter bridge, 7 is the SiN film, and 8 , 9 is a bonding pad, and 10 is an AI coating that is plastically deformed.

When a PCT test is performed on a device having such a structure, a large stress is applied to the chip surface due to swelling of the molding resin surrounding the semiconductor chip. Therefore, a large stress is applied to the interface between the SiN film 7 and the 5i02 film 4, which have a large difference in coefficient of thermal expansion, but the AI formed at this interface
Since the coating 10 is plastically deformed, this stress is alleviated and no cranking occurs. Therefore, the intrusion of water from this part is also prevented, making full use of the excellent characteristics of the SiN film as a pansivation film, which is dense and hard and has a great blocking effect against the intrusion of impurities. Can be done.

In addition, in the above example, a case was explained in which an AI gold film was applied as a plastically deformable film, but an organic film such as a polyimide film may also be applied, and the same effect as in the above example can be obtained. Of course.

〔Effect of the invention〕

As described above, according to the semiconductor device according to the present invention, S
Since a plastically deformable film is deposited directly under the edge of the overcoat film made of iN, it is possible to prevent the occurrence of cracks and water intrusion at the interface between the SiN film and the 5i02 film, and it can be used as a pansivation film originally intended for the StN film. This makes it possible to take full advantage of the excellent properties of this material and greatly improve the moisture resistance of the device.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a semiconductor device according to an embodiment of the present invention, FIG. 2 is a sectional view showing a conventional semiconductor device, and FIG. 3 is for explaining a crank that occurs at the interface between the SiN film and the 5i02 film. FIG. 1 is a collector, 2 is a base, 3 is an emitter, 4 is an oxide film, 5 is a base electrode, 6 is an emitter electrode, 7 is a silicon nitride film, and 10 is a plastically deformable film. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (3)

[Claims] (1) In a semiconductor device in which an overcoat film made of silicon nitride is deposited on the surface of a semiconductor chip, the overcoat film shall have a plastically deformable film deposited directly under all edges thereof. A semiconductor device characterized by: (2) The semiconductor device according to claim 1, wherein the plastically deformed film is a metal film. (3) The semiconductor device according to claim 1, wherein the plastically deformed film is an organic film.