JPH04106957A - Manufacturing method of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce pinholes and microcracks, and improve a moisture and contamination resistance, and further, make a semiconductor device hard to be affected from the outside, by depositing a vapor growth oxide film on the wiring made of aluminum alloy directly, and by forming a nitride film thereon after performing an etchback. CONSTITUTION:On the principal surface of a single crystal silicon substrate 11, phosphorus glass film 12 is deposited, and thereon, a wiring layer 13 made of aluminum allay is formed. Thereafter, an interlayer insulation film 14 is formed by a CVD method. Then, by an anisotropic plasma etching method, the interlayer insulation film 14 is removed halfway, and thereon, by a plasma CVD method, a nitride film 15 is formed as a surface protection film. Further, when the film 14 having grooves, which are deep and have a tendency to overhang near their opening parts, is subjected to an etchback, its protruding parts are etched rapidly. As a result, the deep grooves and overhang parts are eliminated. Thereby, an irregular shape caused by a multilayer wiring structure is changed into a smooth surface shape, and there is no extremely thin part in the nitride film 15. Therefore, pinholes and microcracks are prevented from generating, and a moisture and contamination resistance can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device having multilayer wiring and fine wiring, and more particularly to a method for forming a surface protection film (passivation film) therefor.

[Prior Art] In recent years, in order to improve the degree of integration of semiconductor devices, it has become important to reduce element dimensions and increase the number of interconnect layers. Two to three layers of aluminum wiring have come to be used not only in gate arrays and standard cells, but also recently in memories.

However, with the increase in the number of layers of fine wiring, problems have arisen regarding the reliability of semiconductor devices.

In particular, pinholes and microcracks occur in the surface protective film, which is easily affected by the surface shape and structure of the two-hand conductor device, and when it is sealed in a plastic package, problems such as moisture resistance tend to occur.

A conventional semiconductor surface protection film will be described with reference to FIGS. 4 and 5, which are partial structural sectional views of a semiconductor device.

As shown in FIG. 4, a phosphorus glass film 42 is deposited on the main surface of a single crystal silicon substrate 41, and a wiring layer 43 made of an aluminum alloy is formed thereon.

In this figure, the elements formed in the single crystal silicon substrate 41 are omitted, and only the wiring portion made of aluminum alloy is shown.

Further, M44 nitride is formed on the surface as a surface protective film to prevent external influences such as moisture and dirt on the element.

Such conventional methods have the following problems. That is, when the width of the aluminum alloy wiring becomes narrow and the wiring interval becomes small, the nitride film as a surface protection film is not uniformly formed on the side surfaces of the wiring, and the spaces between the wirings become groove-like. and,
The film thickness of the sidewall of the aluminum alloy wiring becomes extremely thin, causing microcracks and pinholes to occur, which causes a decrease in the moisture resistance and dirt resistance of the device.

The step coverage of the nitride film, which is a surface protective film, becomes worse as the unevenness of the surface of the semiconductor device increases due to multilayer wiring, and its effectiveness as a surface protective film decreases.

As shown in FIG. 5, a phosphor glass film 52 is deposited on the main surface of a single crystal silicon substrate 51, and a first wiring layer 53 made of an aluminum alloy is formed thereon. Furthermore, a glabellar insulating film 54 is formed thereon, and a second wiring layer 55 made of an aluminum alloy is formed thereon. The top layer is M56 nitride as a surface protection film.
is formed.

With such a surface structure, as in the previous example, the step coverage for surface protection is poor and pinholes are likely to occur, which has a large effect on the moisture resistance and contamination resistance of the device.

As described above, in the conventional method, the effect of the surface protective film is insufficient, and high-density fine wiring and multilayer wiring have problems in terms of reliability of semiconductor devices.

[Problem to be Solved by the Invention 1] Surface protective films formed by conventional methods have poor step coverage for complex surface shapes, which tends to cause pinholes and microcracks, and has poor moisture resistance and stain resistance. This poses a major problem in terms of reliability. In particular, multilayer wiring,
This problem is becoming more pronounced as wiring becomes finer.

Therefore, reducing pinholes and microcracks,
There is a need for a surface protective film for semiconductor devices that has good moisture resistance and contamination resistance, and is less susceptible to external influences.

[Means for Solving the Problems] (1) The first method of the present invention is to deposit a vapor-phase grown oxide film directly on an aluminum alloy wiring, and to subject the deposited vapor-phase grown oxide film to an anisotropic plasma. A method in which a nitride film is formed after performing etchback using an etching method.

(2) The second method of the present invention is the same as the first method until forming the nitride film, but after performing etchback and forming the second vapor phase growth film, the nitride film is removed. How to form.

(3) Another method of the present invention is that after etchback, SO
There is a method of forming a nitride film after forming a G film.

[Example] Figures 1(a) to 1(C), Figures 2(a) to 2(C), and Figures 3(a) to 3(c) show examples of semiconductor devices. The present invention will be described in detail below by showing schematic cross-sectional views of each step.

As shown in FIG. 1(a), a phosphorus glass film 12 is deposited on the main surface of a single crystal silicon substrate 11, a wiring layer 13 made of an aluminum alloy is formed thereon, and then an interlayer insulating film 1
4 is formed by CVD method.

As shown in FIG. 1(b), the interlayer insulating film 14 is etched away halfway by an anisotropic plasma etching method.

As shown in Figure 1(C): Two plasma CVD
Nitriding as a surface protective film by the method! Make 15 squares.

According to the method of the present invention, when an interlayer insulating film that has deep grooves and is formed with a slight overhang is etched back using an anisotropic plasma etching method, the convex portions are quickly etched, the deep grooves are eliminated, and the overhang is removed. The department will also disappear.

A gentle sidewall is formed on the side of the wiring. If a nitride film is formed thereon as a surface protective film, the thickness will be sufficiently thick even at the stepped portions because the steps are gentle. Therefore, pinholes and microcracks are less likely to form in the nitride film at the corners of the groove.

In the second method, as shown in FIG. 2(a), a phosphorus glass film 22 is deposited on the main surface of a single crystal silicon substrate 21, a wiring layer 23 made of an aluminum alloy is formed thereon, and then a wiring layer 23 made of an aluminum alloy is formed. The first interlayer insulation 1124 is formed by the C-'D method. As shown in FIG. 2(b), the first interlayer insulating film 24 is partially etched away using an anisotropic plasma etching method.

As shown in FIG. 2C, after a second interlayer insulating film 25 is formed thereon, a nitride film 26 as a surface protection film is formed by plasma CVD.

The reason for forming the second interlayer insulating film 25 is to further smooth out the unevenness that has been smoothed by the first interlayer insulating film 24.

As shown in FIG. 3(a), the third method is to deposit a phosphorus glass film 32 on the main surface of a single crystal silicon substrate 31, form a wiring layer 33 made of an aluminum alloy thereon, and then apply an interlayer The insulating film 34 is formed by the CVD method. As shown in FIG. 3(b), the interlayer insulating film 34 is etched away halfway by anisotropic plasma etching.

As shown in FIG. 3C, after spin-coating and baking an SOG film 35 thereon, a nitride film 36 is formed as a surface protection film by plasma CVD.

The reason why 5OG135 is used is to further fill in the groove that has become smooth with the glabellar insulation 11i34 and further reduce unevenness.

[Effects of the Invention] As described above, according to the present invention, although not shown in the examples of fine wiring and the present invention, it is possible to smooth the uneven shape caused by the multilayer wiring structure and to By using it as a surface protective film for the structure, the nitride film does not become extremely thin in any place, preventing the occurrence of pinholes and microcracks, and improving moisture resistance and stain resistance.

[Brief explanation of drawings]

Figure 1(a) to Figure 1(C), Figure 2(a) to Figure 2(
c) and FIGS. 3(a) to 3(c) are schematic cross-sectional views showing the manufacturing process of the method of the present invention in the order of steps. 4 and 5 are schematic cross-sectional views of the structure of a conventional semiconductor device. i2) Sword (1) Hand 2i"1(c) th") [1(α) Ne 3 Figure (1)) Chest 3) Side CC)

Claims (4)

[Claims] (1) A method for manufacturing a semiconductor device in which a passivation film is formed on a metal wiring layer such as an aluminum alloy, including: a) forming the metal wiring as the uppermost layer on a semiconductor substrate; b) vapor phase. c) etching back the vapor-grown oxide film using an anisotropic plasma etching method; and d) forming a plasma nitride film. A method for manufacturing a semiconductor device. (2) The method for manufacturing a semiconductor device according to claim 1, wherein the vapor-grown oxide film is a SiO_2 film or a phosphorous glass film. (3) A method for manufacturing a semiconductor device in which a passivation film is formed on a metal wiring layer such as an aluminum alloy, which includes: a) forming the metal wiring as the uppermost layer on a semiconductor substrate; b) a first step; c) etching back the first vapor grown oxide film using an anisotropic plasma etching method; d) forming a second vapor grown oxide film. A method for manufacturing a semiconductor device, comprising the steps of: e) forming a plasma nitride film. (4) A method for manufacturing a semiconductor device in which a passivation film is formed on a metal wiring layer such as an aluminum alloy, including: a) forming the metal wiring as the uppermost layer on a semiconductor substrate; b) vapor phase. a step of forming a grown oxide film; c) a step of etching back the vapor-grown oxide film using an anisotropic plasma etching method; d) a step of coating and forming an SOG (abbreviation of SPINONG LASS) film; e) plasma nitriding. A method for manufacturing a semiconductor device, comprising the steps of forming a film.