JPS63107141A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form an aluminum wiring characterized by less wire breakdown, by depositing a polycrystalline silicon film on an insulating film before an electrode window is formed, opening and forming the window in both films simultaneously, depositing an aluminum film on the upper surface including the electrode window, forming an electrode and the aluminum wiring, thereby forming a gentle taper surface around the electrode window. CONSTITUTION:A PSG film 2 and a polycrystalline silicon film 10 are laminated and deposited on a semiconductor substrate 4. Then a resist film mask 5 for opening an electrode window is formed on the upper surface. The polycrystalline silicon film 10 and about one half of the PSG film 2 are isotropically etched by plasma etching. Then the remaining one half of the thickness of the PSG film 2 undergoes anisotropic etching, and the electrode window 13' is formed. Thereafter, the resist film mask 5 is removed, and an aluminum film 11 is deposited by sputtering. At this time, since the electrode window has a gently tapered side surface, the aluminum film is thickly deposited on the side of the electrode window. Thereafter, the aluminum film 11, under which the polycrystalline silicon film 10 is provided, is patterned, and a wiring is formed.

Description

[Detailed Description of the Invention] [Summary] Before opening an electrode window, a polycrystalline silicon film is deposited on an insulating film, both films are opened simultaneously to form an electrode window, and the upper surface including the electrode window is An aluminum film is deposited on the insulating film, and the aluminum film and the polycrystalline silicon film are patterned together to form an aluminum wiring with the polycrystalline silicon film as the lower layer on the insulating film.

This will reduce disconnections in the wiring layer and bridge portions of the aluminum wiring.

[Industrial Field of Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming aluminum wiring.

In semiconductor devices such as ICs and LSIs, a large number of elements are provided on a semiconductor substrate, and electrode wiring is formed to connect these elements. Aluminum (AI) is most often used as a wiring material for such ICs because aluminum has good electrical conductivity and is a material that can be obtained at low cost.

On the other hand, the biggest cause of reduced IC reliability is problems such as disconnections and short circuits in wiring layers, and countermeasures have been taken for a long time, but as ICs become more highly integrated and miniaturized, countermeasures are becoming more and more difficult. This is becoming increasingly difficult, and therefore, countermeasures suitable for the fine electrodes and wiring are desired.

[Prior art and problems to be solved by the invention] Figure 2 shows a plan view of aluminum wiring in an IC. 1 is an aluminum wiring, 2 is an insulating film, and as shown in the figure, normal wiring The width is narrow, for example, 2μm, but it is 1.2μm.
The connection portion with the mφ electrode 3 (indicated by a dotted line) is made to have a wiring width of 4 μm, which is about twice as wide, in order to prevent disconnection.

FIGS. 3(a) to 3(C) show cross-sectional views of the conventional aluminum wiring forming process in the portion shown in FIG. 2. First, as shown in FIG.
A resist film mask 5 for opening an electrode window is formed on the insulating film consisting of m) by a photo process.

Next, as shown in FIG. 3 (bl), dry etching is performed using a fluorine-based reactive gas to uniformly etch to about half the thickness of PSGS2O2.
An undercut having a width comparable to the etching depth is formed under the resist film mask 5.

Next, as shown in the same figure (C1), the remaining half of the PSGS2O2 thickness is anisotropically etched to open an electrode window (contact hole) of 3° with a diameter of 1.2 μmφ.

Next, the resist film mask 5 is removed, as shown in FIG. 3(d).
As shown in FIG. 2, an aluminum film 1 having a thickness of about 1 μm is deposited. Thereafter, although not shown, another resist film mask is formed, and the aluminum film is patterned to form aluminum wiring.

However, when aluminum is deposited by sputtering or vapor deposition, the coverage of the recesses is poor due to the directionality of the deposition, and as shown in the cross-sectional view of FIG. 3(d), the electrode window The problem is that the aluminum film is only thinly deposited inside the electrode window due to the steep taper (slope) of the side surface, and therefore, the wire is easily broken at this electrode portion.

Further, since the aluminum wiring is provided on an insulating film such as a PSG film, there is a drawback that phosphorus in the PSG film absorbs moisture, and the aluminum is easily oxidized by the moisture, resulting in wire breakage.

The present invention proposes a manufacturing method that reduces both of these two problems and reduces wire breaks.

[Means for solving the problem] The purpose is to stack an insulating film and a polycrystalline silicon film, open a window in the insulating film and the polycrystalline silicon film at the same time to form an electrode window, and A semiconductor device comprising the steps of: depositing an aluminum film on the polycrystalline silicon film containing the polycrystalline silicon film, and simultaneously patterning the aluminum film and the polycrystalline silicon film to form an aluminum wiring connected to the electrode window. This is achieved by the manufacturing method.

[In other words, in the present invention, before opening an electrode window, a polycrystalline silicon film is deposited on an insulating film, and both films are opened simultaneously to form an electrode window, and the upper surface including the electrode window is An aluminum film is deposited on the substrate, the electrodes are filled with the aluminum film, and a wiring made of an aluminum film/polycrystalline silicon film is formed on the insulating film.

By doing so, the periphery of the electrode window will be formed into a gentle taper, and the electrode window will have a thick coating of aluminum, reducing disconnections (and the wiring layer on the insulating film will have a polycrystalline silicon film interposed underneath). This reduces disconnections due to moisture intrusion.

[Example] Hereinafter, embodiments will be described in detail with reference to the drawings.

FIGS. 1(a) to 1(d) are sequential sectional views of the forming steps according to the present invention.

As shown in FIG. 1(a), a polycrystalline silicon film 10 having a thickness of 1 to 1.5 μm and a polycrystalline silicon film 10 of 500 to 2,000 layers is deposited on a semiconductor substrate 4 by chemical vapor deposition. This polycrystalline silicon film contains phosphorus and is made into a conductive film with sheet resistance reduced to about 60Ω.

Next, as shown in FIG. 1(b), a resist film mask 5 for opening an electrode window is formed on the upper surface, and C
Using F4+02 gas as a reaction gas, the polycrystalline silicon film 10 and PSGS2O2 are etched by microwave-excited plasma etching, and the polycrystalline silicon film 10 and PSGS2O2 are uniformly etched to a film thickness of about PSGS2O2. Then, the etching speed of the polycrystalline silicon film 10 is about twice as fast as the PSGS2O2 etching speed, so that the polycrystalline silicon film 10 is first etched laterally and deeply below the resist film mask 5, creating an undercut. Next, since the lower PSGS2O2 is etched, an electrode window 13' having a gentle taper as shown in the figure is formed.

Next, as shown in FIG. 1(C), the remaining half of the PSGS2O2 thickness was anisotropically etched using CF4, CHF3, or a mixture thereof as a reaction gas to form a 1.2 μm diameter
An electrode window 13'' is formed in this anisotropic etching process using an etching method called active ion etching (RIE), which is etched vertically along the resist film mask.

Next, the resist film mask 5 is removed, and as shown in FIG. Therefore, there is a thickness (
An aluminum film is deposited.

Thereafter, although not shown, the aluminum film 11 with the polycrystalline silicon film 10 interposed therebetween is patterned to form wiring.

Then, the electrode window 13° is buried only with the aluminum film, and on the PSG film, an aluminum film-based wiring consisting of an aluminum film/polycrystalline silicon film (top/bottom) is formed. In such a wiring layer, the electrode window is coated with aluminum thickly, so there are few disconnections, and the wiring on the PSG film has a polycrystalline silicon film interposed in the lower layer, so there is no possibility of moisture intrusion into the aluminum film. This reduces wire breakage due to aluminum oxidation. Therefore, the formation method according to the present invention is useful for increasing the reliability of semiconductor devices such as ICs.

[Effects of the Invention] As is clear from the above description, the present invention has a significant effect on improving the reliability of semiconductor devices such as ICs.

[Brief explanation of the drawing]

Figures 1 (al to d) are cross-sectional views in the order of the formation process according to the present invention, Figure 2 is a cross-sectional view of an aluminum wiring, and Figure 3 (al to (dl) are cross-sectional views in the order of the conventional formation process. 1.11 is an aluminum wiring or an aluminum film, 2 is an insulating film or a PSG film, 3 is an electrode, 3', 13' are electrode windows, 4 is a semiconductor substrate, 5 is a resist film mask, 10 is a polycrystalline silicon film Figure 1: Luminiqueum Nishi e Itomitsu d1 Toj Figure 2: Subordinate boat's dimensions and 11-sided autoanalysis Figure 1 Aluminum order image e, tc) → N$ 11' Hara 111Mko Figure 3

Claims (1)

[Claims] An insulating film and a polycrystalline silicon film are laminated, an electrode window is formed by simultaneously opening the insulating film and the polycrystalline silicon film, and an aluminum film is deposited on the polycrystalline silicon film including the electrode window. A method of manufacturing a semiconductor device, comprising the steps of simultaneously patterning the aluminum film and the polycrystalline silicon film to form an aluminum wiring connected to the electrode window.