JPS61284928A - Semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor device having high migration resistance and high reliability in which no defect phenomena of the aluminium alloy wiring occurs, by making the compressive stress of a silicon nitride film by the CVD method as the final protective film or the inter-layer insulating film not greater than a specific value. CONSTITUTION:In a semiconductor device employing a silicon nitride film which has been formed by means of the plasma CVD method as the final protective film 13, 17 or the inter-layer insulating film 15 in a multilayer wiring, the compressive stress of said silicon nitride film is made not greater than 5X10<9>dyne/ cm<2> on the basis of conversion to 1mum film thickness. The defect phenomena of aluminium alloy wirings 2, 4, 6 becomes easier to occur as the compressive stress of plasma CVD silicon nitride films 13, 15, 17 becomes greater and as the film thickness becomes greater. However, the defect phenomena does not occur if the compressive stress is not greater than 5X10<9>dyne/cm<2> for the film thickness of 1mum, not greater than 2.5X10<9>dyne/cm<2> for the film thickness of 2mum, and not greater than 10X10<9>dyne/cm<2> for the film thickness of 0.5mum. A method for making the compressive stress of the plasma CVD nitride film small is, for instance, to make the pressure at the formation of the film high.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device using a silicon nitride film formed by plasma CVD as a final protective film or an interlayer insulating film of multilayer wiring.

[Conventional technology]

A conventional device of this type is shown in FIG. In the figure, 1 is a PSG film, 2 is an aluminum alloy wiring, and 3 is a final protective film, which is a silicon nitride film formed by plasma CVD.

Another conventional example is shown in FIG. In the figure, 4 is 1
5 is an interlayer insulating film, 6 is a second layer aluminum alloy wiring, and 7 is a final protective film.

The interlayer insulating film 5 and the final protective film 7 are silicon nitride films formed by plasma CVD.

Next, the manufacturing flow will be explained for the aluminum two-layer wiring structure shown in FIG. After forming the first layer aluminum alloy wiring 4, a silicon nitride film is deposited as an interlayer insulating film 5 by plasma CVD. Next, a through hole is made in the interlayer insulating film 5 to connect the first and second layer aluminum alloy wires 4 and 6, and a second layer aluminum alloy wire 6 is formed. Finally, the final protective film 7
Then, a silicon nitride film is deposited by plasma CVD.

In such a semiconductor device, a silicon nitride film formed by plasma CVD has a thickness of 6 to 12×109 dyn.
e/ca! Therefore, when used as the final protective film 31.7 or the interlayer insulating film 5 of multilayer wiring, the underlying aluminum alloy wiring 2, 4.6 will be damaged during the silicon nitride film deposition and subsequent heat treatment process. On the other hand,
Mechanical damage is caused, for example, as shown in FIGS. 6 and 7, a defective portion 8 is created in the aluminum alloy wiring 2.

In addition, this large compressive stress is caused by aluminum alloy wiring 2.4
．． It is known that the migration resistance of 6 is significantly deteriorated.

[Problem that the invention seeks to solve]

The conventional semiconductor device is constructed as described above, and the silicon nitride film formed by plasma CVD method has a thickness of 6 to 12X.
l 09dyne/cll! Because it has a large compressive stress, if it is used as a final protective film or an interlayer insulating film for multilayer wiring, it may cause mechanical FJM damage to the underlying aluminum alloy wiring, causing damage to the aluminum alloy wiring, or causing damage to the wiring. The drawback was that it caused a significant deterioration in migration resistance.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional devices, and its purpose is to provide a highly reliable semiconductor device that does not cause defects in aluminum alloy wiring, has high migration resistance, and is highly reliable. It is said that

[Means for solving problems]

This invention provides a semiconductor device in which a silicon nitride film formed by plasma CVD is used as a final protective film or an interlayer insulating film.
/crA or less.

[Effect]

In this invention, since a silicon nitride film with low compressive stress is used, there is almost no mechanical damage to the underlying aluminum alloy wiring during deposition of the silicon nitride film or during the subsequent heat treatment process, and the aluminum The migration resistance of the alloy wiring also hardly deteriorates.

(Example) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a semiconductor device according to an embodiment of the present invention. In the figure, 1 is PSGHfA, 2 is aluminum alloy wiring, 1
3 is the final protective film, which is formed by the plasma CVD method and has a compressive stress of 5 x 109 d when converted to a film thickness of 1 μm.
This is a silicon nitride film with a thickness of yne/ad or less.

Next, the effects will be explained.

The above-mentioned defective phenomenon of aluminum alloy wiring occurs more easily as the compressive stress of the plasma CVD silicon nitride film increases and as the film thickness increases. If the compressive stress is below, the chipping phenomenon will not occur. That is, when the film thickness is 2 μm, it is 2.5 × 109 dyne/c1a or less, and when the film thickness is 0.5 μm, it is 10 × 109 dyne/c.
It is sufficient if it is less than or equal to ot.

In a normal diffusion furnace type plasma CVD apparatus, when the film formation temperature is 300 to 400°C, the temperature is 1.0 to 2°OTorr.
The plasma CVD nitride film formed under a pressure of 6~
It has a compressive stress of 12 x 109 dyne/cJ.

One way to reduce the compressive stress of such a plasma CVD nitride film is to increase the pressure during film formation. In the above example, the film forming pressure is set to 2. OTo
By increasing the compressive stress to 5 x 10
It can be reduced to 9 dyne/c4 or less.

In the apparatus of this embodiment as described above, the low stress plasma C
Since the VD nitride film is used, the defect phenomenon of the aluminum alloy wiring does not occur, and deterioration of the migration resistance of the wiring can be prevented.

In the above embodiment, a low-stress plasma CVD silicon nitride film was used as the final protective film for the single-layer aluminum wiring, but as shown in FIG. 2, the interlayer insulating film 15. The same effect can be obtained even when applied to the final protective film 17.

Furthermore, as shown in FIG. 3, even when a silicon oxide film is used as the interlayer insulating film 10 of the aluminum layer wiring and a silicon nitride film is used as the final protective film 17, mechanical damage to the second layer aluminum alloy wiring 6 can be prevented. For this reason, it is possible to use a low-stress silicon nitride film, or because the compressive stress of the plasma CVD silicon nitride film used as an interlayer insulating film is 5 x 109 dyne/cTA or less when converted to a film thickness of 1 μm, an aluminum alloy can be used. Does not cause wiring defects,
This has the effect of providing a semiconductor device with high wiring migration resistance.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a semiconductor device according to an embodiment of the present invention;
2 is a cross-sectional view of another embodiment of the present invention, FIG. 3 is a cross-sectional view of still another embodiment of the present invention, FIGS. 4 and 5 are cross-sectional views of a conventional semiconductor device, and FIG. The figure is a plan view for explaining the conventional problems, and FIG. 7 is a sectional view taken along the line A--A in FIG. 6. In the figure, 13 and 17 are final protective films, and 15 is an interlayer insulating film. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Patent Attorney Ken Hayase - Fig. 1 13:, 4 rustic layer Fig. 2 15: Maro 67.11 layer 1 17: pPay7H Fig. 3 Fig. 4 Fig. 5

Claims (1)

[Claims] (1) In a semiconductor device using a silicon nitride film formed by plasma CVD as a final protective film or an interlayer insulating film of multilayer wiring, the silicon nitride film has a compressive stress of 5×10 when converted to a film thickness of 1 μm. ＾9dyne/cm
A semiconductor device characterized in that it is ^2 or less.