JPH04102329A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enhance a moistureproof property and reliability by a method wherein, after an insulating film has been deposited on a semiconductor substrate by a vapor growth method, the insulating film is etched back and sidewalls composed of the insulating film are formed on side faces of metal wiring CONSTITUTION:A vapor-growth silicon oxide film 7 is deposited on the surface of a semiconductor substrate which is provided with the following: a semiconductor element composed of a field oxide film 2, a diffusion layer 3, a polycrystalline silicon interconnection 4 and the like; an interlayer insulating film 5; and aluminum wiring 6. Then, the film 7 is etched back by an anisotropic dry etching operation. Thereby, sidewalls 7a composed of the film 7 are formed on side faces of the wiring 6. In succession, a vapor-growth phosphosilicate glass PSG film 8 is deposited. In succession, a silicon nitride film 9 is deposited. Thereby, since the production of an overhang or the like is suppressed, the shape of a surface protective film becomes good, the moistureproof property is improved the and life is extended.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of manufacturing a surface protection film formed on metal wiring.

[Conventional technology]

A conventional semiconductor device had a cross-sectional structure as shown in FIG. 3, for example. A semiconductor device having such a structure has been manufactured by the method described below.

Field oxide film 2 formed on the surface of silicon substrate 1.
Diffusion layer 3. It has a semiconductor element composed of polycrystalline silicon wiring 4 and the like, and has an interlayer insulating film 5 made of, for example, a BPSG film.
．． and a semiconductor substrate having an aluminum wiring 6 with a film thickness of about 1.0 to 1.5 μm, and a film thickness of 0.4 to 0.8 μm.
A vapor phase grown PSG film 18 with a thickness of about m is deposited, and a silicon nitride film with a thickness of about 0.2 to 0.8 μm is further deposited.
A surface protective film was formed by the vapor-phase grown PSG film 18 and the silicon nitride film.

Note that the silicon nitride film in this case is not necessarily composed of a single film; for example, the silicon nitride film 19 a
+ 19 b, 19 c, 19 d + 1
9 e19f, 19g, 19h, and 19i.

Another example of a semiconductor device had a cross-sectional structure as shown in FIG. A semiconductor device having such a structure has been manufactured by the method described below.

Field oxide film 2 formed on the surface of silicon substrate 1.
Diffusion layer 3. It has a semiconductor element composed of polycrystalline silicon wiring 4 and the like, and has an interlayer insulating film 5 made of, for example, a BPSG film.
．． And on a semiconductor substrate having an aluminum wiring 6 with a film thickness of about 1.0 to 1.5 μm, a film with a film thickness of 0.1 to 0.5 μm is
A silicon nitride film 29 with a thickness of approximately 2 m is deposited, and the film thickness further increases to 2
．． A silicon polyimide film 20 having a thickness of about 0 to 10.0 μm was applied and formed, and a surface protection film was formed by a silicon nitride film 29 and a silicon polyimide film 20.

[Problem to be solved by the invention]

In the semiconductor device shown in FIG. 3, since the film thickness of the aluminum wiring θ is as thick as about 1.0 to 1.5 μm, a vapor-phase grown PSG film 18, which is the first surface protection film, is formed on the aluminum wiring θ by 0.4 μm. ~
If the thickness is about 0.8 μm, the step coverage of the vapor-phase grown PSG film 18 at the end of the aluminum wiring 6 becomes very poor, and the film is deposited in an overhang state at this portion.

When a silicon nitride film, which is a second surface protection film, is deposited in such a state, the silicon nitride film is not necessarily a single film as shown in the figure, but the silicon nitride film 19a,
19 b, 19 c, 19 d, 19
e, 19 f + 19 g + 19 h +
and 19i, it is deposited in a plurality of divided shapes. As a result, slits occur in the silicon nitride film.

As a result, the effect of the second surface protective film, which is intended to prevent water intrusion, is lost, resulting in a major drawback in terms of reliability, such as deterioration of moisture resistance.

In addition, such a structure has a highly uneven surface, so when this semiconductor device is encapsulated with resin, the surface of the semiconductor device and the encapsulating resin will strongly engage, resulting in thermal stress. The aluminum wiring moves at the same time as the sealing resin moves, resulting in displacement of the aluminum, causing problems such as short-circuits or disconnections between the aluminum wirings.

In the semiconductor device shown in FIG.
Although the flatness of the surface of the semiconductor device is obtained by using a thickness of about 0.0 μm, there is a drawback that a UV PROM cannot be formed with this structure because the organic film does not transmit ultraviolet rays (λ cape 26 nm).

[Means to solve the problem]

The method for manufacturing a semiconductor device of the present invention includes the steps of: depositing an insulating film by vapor phase growth on a semiconductor substrate on which a predetermined semiconductor element one-layer insulating film and metal wiring are formed; and etching back the insulating film. forming a side wall made of the insulating film on a side surface of the metal wiring; and depositing a first surface protection film and a second surface protection film on the semiconductor substrate. I'm here.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) to 1(C) are cross-sectional views in order of steps for explaining a first embodiment of the present invention.

First, as shown in FIG. 1(a), a field oxide film 2. Diffusion layer 3. It has a semiconductor element composed of polycrystalline silicon wiring 4 and the like, and has an interlayer insulating film 5 made of, for example, a BPSG film. and film thickness is 1.0
Aluminum wiring 6 which is a metal wiring of ~1.5 μm
A vapor phase grown silicon oxide film 7 is deposited to a thickness of approximately 0.8 to 1.6 μm on a semiconductor substrate having a semiconductor substrate.

Next, as shown in FIG. 1(b), by etching back the vapor-phase grown silicon oxide film 7 by anisotropic dry etching, side walls made of the vapor-phase grown silicon oxide film 7 are formed on the sides of the aluminum wiring 6. Form 7a.

Subsequently, as shown in FIG. 1C, a vapor phase grown PSG film 8, which is a first surface protection film, is deposited to a thickness of about 0.5 to 1.0 μm. Subsequently, a silicon nitride film 9, which is a second surface protection film, is deposited to a thickness of about 0.2-0.8 μm.

FIG. 2 is a sectional view for explaining a second embodiment of the present invention.

This embodiment relates to a method of manufacturing a semiconductor device consisting of two layers of aluminum wiring.

The steps up to the formation of the side walls 7a of the aluminum wiring 6 (first layer aluminum wiring) are the same as in the first embodiment of the present invention. Thereafter, a silicon nitride film 10 as a second interlayer insulating film is grown by plasma vapor deposition with a thickness of 0.5 to 1.
．． A thickness of about 0 μm is deposited.

Next, a through hole is opened in the silicon nitride film 10, and a second
A layer of aluminum wiring 6a is formed. Next, a vapor-phase grown silicon oxide film is deposited to a thickness of about 0.8 to 1.5 μm, and this is etched back by anisotropic dry etching to form a side wall 7b made of a vapor-grown silicon oxide film on the side surface of the aluminum wiring 6a. Form.

Subsequently, a vapor phase grown PSG film 8a, which is a first surface protection film, is deposited.
is deposited to a thickness of about 0.5 to 1.0 μm. Subsequently, a silicon nitride film 9a, which is a second surface protection film, is formed at a thickness of 0.2 to 0.
．． A thickness of about 8 μm is deposited.

In this embodiment, a side wall 7a is formed on the side surface of the first layer aluminum wiring 6. Therefore, the coverage of the second interlayer insulating film with respect to the (first layer) aluminum wiring 6 is good even without performing a treatment such as reflow.

Reflecting this shape, in this embodiment, the leakage phenomenon between the first layer aluminum wiring 6 and the second layer aluminum wiring 6a disappears.

Note that although the silicon nitride film 10 is used as the second interlayer insulating film in this embodiment, other insulating films may be used.

〔Effect of the invention〕

As explained above, the method for manufacturing a semiconductor device of the present invention includes:
By forming side walls made of an insulating film on the side surfaces of metal wiring, the shape of the first surface protective film formed thereon is suppressed from overhanging, and the shape is improved.For example, water intrusion is suppressed. The second surface protective film, which is formed for the purpose of preventing this, is uniformly formed and can achieve its original purpose. For example, the moisture resistance life of a semiconductor device to which the present invention is applied is four to five times higher than that of a semiconductor device manufactured by a conventional manufacturing method.

Also, 1st. And since the surface flatness of the second surface protection film is excellent, when a semiconductor device according to the present invention is resin-sealed, disconnection of metal wiring due to thermal stress of the sealing resin and breakage of metal wiring between metal wirings occur. Regarding Soyote, the heat stress resistance is also improved two to three times compared to conventional products.

Furthermore, the UVPROM to which the present invention is applied has good UV erasing characteristics, and it is possible to realize a highly reliable semiconductor device incorporating an EPROM.

FIG.

1... Silicon substrate, 2... Field oxide film, 3
...Diffusion layer, 4...Polycrystalline silicon wiring, 5...
Interlayer insulating film, 6+6a...aluminum wiring,
7... Vapor phase grown silicon oxide film, 7a, 7b... Side wall, 8°8a, 18... Vapor phase grown PSG film, 9.9
a + 1019a, 19b, 19c, 19d, 19
e.

19f, 19g, 19h, 19i, 29... silicon nitride film, 20... silicon polyimide film.

Claims (1)

[Scope of Claims] A step of depositing an insulating film by a vapor phase growth method on a semiconductor substrate on which a predetermined semiconductor element, an interlayer insulating film, and a metal wiring are formed; and etching back the insulating film, The method includes the steps of: forming a sidewall made of the insulating film on a side surface of the metal wiring; and depositing a first surface protection film and a second surface protection film on the semiconductor substrate. A method for manufacturing a semiconductor device.