JPS61296738A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve characteristics of a semiconductor element by setting a series resistance at several tens of ohms so that barrier is not generated at the contact region between a first aluminum electrode and a second aluminum electrode. CONSTITUTION:An impurity region 2 and an oxide film 3 is formed on a silicon substrate 1, a contact hole 4 which is connected to the impurity region 2 is opened to the oxide film 3, and an aluminum layer 5 which is connected to the impurity region 2 is also formed. Next, after forming a first aluminum electrode 6, a plasma nitride film 7 is formed covering the main surface in view of protecting the first aluminum electrode surface 6 from oxidation or corrosion in the successive processes. Moreover, a polyimide film 8 is formed covering the main surface of the plasma nitride film and then the polyimide film on the first aluminum electrode electrically connected to the impurity region 2 is removed by the photoetching method. Thus the surface of plasma nitride film 7 is exposed and is then subjected to the hardening process. The exposed plasma nitride film 7 is then etched and thereby the chemically stable first aluminum electrode connected to the second aluminum electrode is exposed. Thereafter, an aluminum layer 9 which will serve as the second aluminum electrode is immediately formed and the second aluminum electrode 10 is then formed by the photoetching method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a semiconductor device having a two-layer or multilayer electrode structure using an aluminum layer or an aluminum alloy layer containing several percent silicon in aluminum.

[Technical background of the invention and its problems]

Conventionally, a manufacturing method as shown in FIG. 2 is generally used as a method for wiring aluminum electrodes in multiple layers on a semiconductor substrate on which circuit elements are formed.

That is, 8 formed on a semiconductor substrate 10 made of silicon or the like.
A window for forming a first aluminum electrode is formed in the first insulating layer 20 such as i02, and an aluminum film is deposited to a thickness of 0.5 μm to 1 μm by means such as an electron beam or resistance heating, and a photosensitive resin film is formed. The first aluminum electrode 30 is formed using the following method.

Next, in order to form the second aluminum electrode, an insulating layer 40 of polyimide or the like is formed over the entire area including the first aluminum electrode wired on the semiconductor substrate, and the insulating layer on the first aluminum electrode is photosensitive. After removing the resin film and making an opening for connecting the second aluminum electrode, a second aluminum electrode 50 is formed.

This conventional method for manufacturing a multilayer aluminum electrode structure has the following problems.

In order to bring the second aluminum electrode into contact with the first aluminum electrode and perform multilayer wiring, the surface of the first aluminum must be kept in an aluminum state.

However, although it is necessary to use hydrazine or the like for etching the polyimide film, the surface is oxidized in this contact forming step, and a barrier layer 60 is formed.

Furthermore, although the polyimide is thermally cured after the through holes are formed, the surface of the polyimide is oxidized in this step, resulting in the formation of a burnt barrier layer 60. This is a series resistance, and its resistance value ranges from several 100 Ω to several 100 MΩ, which poses a problem in that it significantly deteriorates the characteristics of the semiconductor device.

[Purpose of the invention]

The present invention is the first aluminum! It is an object of the present invention to provide a method for forming a multilayer aluminum electrode wiring that can reduce the barrier goldfish comb series resistance of the contact portion between the pole and the second aluminum electrode to several hundred.

[Summary of the invention]

In the present invention, a plasma nitride film is formed in a region including a first aluminum electrode wired on a semiconductor substrate, and an insulating film (for example, a polyimide film) is further formed on the region to form an insulating film on the first aluminum electrode. An opening is formed at a desired position in the film, the plasma nitride film on the first aluminum electrode is removed, and a second electrode is formed on the exposed first aluminum electrode.
This is a method for forming an aluminum electrode wiring having a multilayer structure to form an aluminum electrode.

〔Effect of the invention〕

According to the method for forming an aluminum electrode with a multilayer structure according to the present invention, no barrier is generated at the contact portion between the first aluminum electrode and the second aluminum electrode, and the series resistance is several tens of thousands.
It is possible to improve the characteristics of a semiconductor device.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

First, as shown in FIG. 1, for example, a thin film region 2 is formed in a predetermined region of a silicon substrate 1 by selectively diffusing impurities. Next, an oxide film 3 covering the thin film region 2 and the surface of the silicon substrate 1 is formed by thermal oxidation or the like.

As shown in the next step (B), in order to form a wiring electrically connected to the impurity region 2, a contact hole 4 communicating with the impurity region 2 is opened in the oxide film 3 by a well-known photolithography method.

Next, an aluminum layer 5 connected to the impurity region 2 through the contact hole 4 is formed on the oxide film to a thickness of about 1 μm by sputter deposition or resistance heating. Here, the aluminum layer 5 contains about several percent of silicon.

Next, as shown in Figure ('C), a desired first aluminum electrode 6 is formed by photolithography, and then N2 and N2
A heat treatment is performed for about 15 minutes in a forming gas consisting of a mixed gas of. Next, a plasma nitride film 7t is formed to cover the main surface.

This plasma nitride film prevents the first aluminum electrode surface 6 from being oxidized and corroded in subsequent steps, thereby maintaining a stable aluminum surface.

Furthermore, a polyimide film 8 is formed to cover the main surface of the plasma nitride film. Next, the first aluminum electrode is heated to 180 to 250 C to degas it, and then the first aluminum electrode is electrically connected to the impurity region 2 by photolithography using a hydrazine solution as shown in Figure (D). The upper polyimide film is removed to expose the surface of the plasma nitride film 7. Thereafter, the polyimide film was heat-cured at 450° C. for 30 minutes.

Next, as shown in Figure (E), the exposed plasma nitride film 7 was removed by chemical dry etching (CDE) using CF4;02 gas (Figure 1G).
A chemically stable first aluminum electrode is exposed which connects to the second aluminum electrode. Immediately thereafter, a second aluminum electrode and a barrel aluminum layer 9 are formed.

Next, as shown in Figure (F), a second aluminum electrode 1 is formed by photolithography.

The multilayer aluminum electrode wiring obtained in this way is the first
No barrier is generated at the connecting portion between the aluminum electrode and the second aluminum' electrode, and the series resistance is several hundred, so that stable semiconductor device characteristics are maintained and the yield can be improved.

[Other embodiments of the invention]

1. described in Examples. Although the 24th pole is made of aluminum wool, it is not limited to aluminum wool, and may be made of a conductive metal such as copper or other metal. Alternatively, instead of the plasma nitride film, an oxide film made of snow ivy may be used.

The plan view and FIG. 2 are cross-sectional views showing the conventional method.

In the figure, 1.10... Silicon substrate, 2... Impurity diffusion region, 3.20... Oxide film layer, 4... Contact hole, 5... Aluminum layer, 6.30... First aluminum electrode, 7... Plasma nitride film, 8.40... Polyimide film, 9... Second aluminum electrode layer, 10.50... Second aluminum electrode, 60... Barrier layer.

Agent: Patent attorney Kensuke Norichika (and 1 other person) Figure 2

Claims (1)

[Claims] A step of forming a plasma nitride film on a region including a first aluminum electrode wired on a semiconductor substrate, a step of forming a polyimide film on the region, and a step of forming a desired shape of the polyimide film on the first aluminum electrode. The method comprises the steps of: opening a window for taking out the electrode at the position; removing the plasma nitride film on the first aluminum electrode; and forming a second aluminum electrode in the opening where the window was opened. A method for manufacturing a semiconductor device, characterized in that: