JPS59110122A - Semiconductor integrated circuit device having nitride film - Google Patents

Abstract

PURPOSE:To enhance water proof characteristic and reliability by providing a film which has good moisture proof characteristic on a thermal oxide film provided on the main surface of semiconductor substrate, covering this film with a nitride film and making the edge of nitride film in contact with the thermal oxide film. CONSTITUTION:A thermally oxidized SiO2 film 2 is formed on a semiconductor substrate 1. A first Al wiring 3 is connected to the element region formed on the Si substrate through an aperture of thermal oxide film 2. The CVD SiO2 film 4 as the interlayer insulating film is formed on the wiring 1 and a second Al wiring 5 is connected to the wiring 3 through an aperture of film 4. The CVD SiO2 film 6 is formed on the surface except for the pad 8 of the second Al wiring. The SiO2 film 4 is removed at the periphery and the film 6 covers the edge of film 4 and extends over the thermal oxide film 2. The plasma silicon nitride film 7 is formed at the surface except for the Al pad and it is in contact with the thermally oxidized SiO2 film.

Description

[Detailed description of the invention] The present invention relates to a semiconductor integrated circuit device with improved thermal characteristics.

[Prior art]

Semiconductor integrated circuit devices, which generally consist of semiconductor elements such as transistors, diodes, semiconductor resistors, and capacitors, interconnected wiring between these elements, and lead extraction terminals, are generally susceptible to moisture, conductive substances, and ions from the outside world. It is known that properties deteriorate when affected by chemical substances. For this reason, methods are being used to surround the surface, particularly the active region that affects its characteristics, and the vicinity thereof with a protective film such as silicone acid (arsenic film). However, it has become clear that one layer is not sufficient. This led to double or multiple protection.

For example, in a double protective film of silicon oxide film and silicon nitride film, the inner protective film silicon oxide film is covered with the outer protective film silicon nitride film, and the silicon oxide film maintains good characteristics with silicon. The structure uses a silicon nitride film to prevent impurities such as moisture from entering. Phosphorus glass (PSG) is also used, but since PSG generally has properties such as high hygroscopicity and easy chemical etching, P and SG are used on silicon oxide (SiC+z).
A triple structure of forming and further covering with 5iU2,
・Moreover, a method has been proposed in which the upper layer is completely sealed with 5iOz.

Silicon nitride film has extremely good shielding properties against moisture and alkali ions, so it is often used as a protective film for the uppermost layer of the diffusion layer. A structure in which the edge of the nitride film is in direct contact with silicon has often been used, but this structure has the problem of damaging the silicon substrate due to the opening in the silicon nitride film, especially when the diffusion is shallow or fine. This is an undesirable problem in high-density integrated circuit devices with patterns.In addition, the protection in this case is only concerned with protecting the diffusion layer, and the wiring section is not protected, so even if the diffusion layer is protected, , the wiring section will be damaged and the semiconductor device will no longer function properly.Also, even if a silicon nitride film is coated on top of the wiring layer for the purpose of protecting the wiring, the structure as shown in Figure 1 will result. Figure 1 is a cross-sectional view showing the wiring structure of a conventional semiconductor integrated circuit.
It is connected to the resistor region formed on the silicon substrate through the opening of the dioxide film 2. 4 is a CVD5i (, 12) as an interlayer insulating film formed on the first Al wiring 3; 5 is a CVD 5i (, 12) formed on the interlayer insulating film 4 connected to the first Al wiring 3 through the opening of the interlayer insulating film 4; This is the second Al wiring.

Further, 6 is C V D SiOz formed on the surface of the second Al wiring except for the pad portion 8, and pl 7 is a silicon nitride film which is the uppermost protective film.

As can be seen from FIG. 1, the outside of the pad portion 8 of the second Al wiring is covered with a thermal oxide film 2. CV of glabellar insulating film
L) Si024, CVD5i026 for Al wiring protection.
Although the plasma silicon nitride films 7 overlap, the ends of each layer are exposed on the side surfaces.

However, since both the CVDSiO2 films 4 and 6 are deposited after the Al wiring is formed, high-temperature oxidation cannot be used, and they are inevitably formed by CVD at a low temperature of 500° C. or less. Therefore, the formed SiOz is less dense than a high-temperature thermal oxide film and has particularly high water absorption and moisture permeability. Therefore, moisture easily reaches the pad portion of the Al wiring through the path 9 from the side of this layer, deteriorating the Al wiring, especially the pad portion, and significantly reducing the reliability of the semiconductor integrated circuit device. There is.

[Purpose of the invention]

The purpose of the present invention is to address the above-mentioned problems.
It is an object of the present invention to provide a highly reliable semiconductor integrated circuit device with excellent water resistance.

[Structure of the invention]

In the present invention, a thermal oxide film is provided on the main surface of a semiconductor substrate,
In a semiconductor integrated circuit device in which a film having lower moisture resistance than the thermal oxide film is provided on the thermally densified film, and a nitride film is provided on the film, the film is densified by the nitride film. ,
Detailed explanation of the present invention based on an embodiment of the nitride film end portion FIG. 2 is a sectional view of a main part of a semiconductor integrated circuit device according to an embodiment of the present invention. In the figure, 1 to 8 represent the same parts as in FIG. The main points in FIG. 2 that are different from FIG. The CVDSiQ2 film 6 formed on the wiring 5 covers the end of the interlayer insulating film 4 and reaches above the thermally oxidized arsenic film 2, similar to the interlayer insulating film 4 that was etched away earlier.
The outer periphery of the pad has been removed to expose the 8iUz2 envelope formed by thermal oxidation. After that hll
A plasma silicon nitride film 7 is formed on the entire surface except for the pad portion, and the silicon nitride film is in contact with the thermally oxidized [H8iQ2 film 2] exposed after the CVDSi02 film has been removed.

That is, according to this embodiment, the upper surface of the semiconductor integrated circuit device is covered except for the pad portion with a plasma silicon nitride film that has extremely low water absorption and water permeability and is impermeable to impurities, and the nitride film is coated by thermal oxidation. Formed dense and water absorbent,
It is in contact with a silicon oxide film that has low water permeability. Furthermore, since the plasma silicon nitride film has very good coverage of stepped portions, etc., there is almost no intrusion of moisture or the like through the silicon nitride film, the thermal oxidation silicon oxide film, and the contact portions thereof.

In addition, the silicon nitride film coating on the second hlJ wiring is not directly attached to Al (it is coated with a silicon oxide arsenic film by CVD, so it does not damage the Ag wiring and has good adhesion. Intrusion of moisture from these parts is unlikely to occur.Furthermore, since the silicon nitride film is not in direct contact with the silicon substrate, damage to the silicon surface that occurs when removing the nitride film can be prevented.

In the case of the example, the results were similar when starting with 500 to 100 OH, and a several-fold improvement in 4 lives was observed.

〔Effect of the invention〕

As described above, according to the present invention, the moisture resistance can be improved without deteriorating the characteristics of a semiconductor integrated circuit device, and the reliability can be significantly improved.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the main parts of a conventional semiconductor integrated circuit device;
The figure is a sectional view of a main part of a semiconductor integrated circuit device according to an embodiment of the present invention. 1...Silicon semiconductor substrate, 2...Thermal acid ratio silicon acid ratio film, 3...First layer hl wiring,
4,6... Silicon acid ratio film by CVD, 5.
...Second layer Ag wiring, 7...Plasma silicon nitride film, 8...Pad portion, 9...
...Water intrusion route.

Claims (1)

[Claims] In a semiconductor integrated circuit device, a thermal oxide film is provided on the main surface of a semiconductor substrate, a film having lower moisture resistance than the thermal oxide film is provided on the oxide film, and a nitride film is provided on the film, A semiconductor integrated circuit device having a nitride film, wherein a film is covered with the nitride film, and an end portion of the nitride film is in contact with the thermal oxide film.