JPS5928360A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain extremely excellent layer conduction by using gas plasma method containing F, when a layer conduction hole is provided through an electric insulation film which covers a W film. CONSTITUTION:A poly Si 24 and the W film 25, by covering the apertures of SiO2 films 22 and 23, are formed on an Si substrate 21 whereon a P or N type conductive layer has been finished in forming. An Si3N4 film 26 is superposed on the surface by plasma vapor growing method, and an aperture 27 is opened by plasma etching method using CF4. Next, an Al layer 28 is provided. This constitution enables to obtain excellent connection between the W layer and the Al layer and then generate no disconnections even in heat treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for forming wiring.

In recent years, due to the demand for higher density and higher performance of semiconductor devices, high melting point metals are often used in wiring layers. In particular, tungsten films have excellent durability such as low resistivity and thermal stability. However, in conventional multilayer wiring semiconductor devices in which wiring layers are made of tungsten or a material containing tungsten as a main component (hereinafter collectively referred to as tungsten), good conduction cannot be obtained between the tungsten layer and other wiring layers. do not have.

For example, in the conventional example shown in FIG.
A silicon oxide film 6 in which desired conductive holes 17 have been formed using a hydrofluoric acid solution is deposited thereon. An aluminum metal layer 18 is formed through the entire opening 17 and connected to the tungsten wiring layer 15. The conduction through the opening 17 was examined and found to be several hundred ohms per hole, and when heat treated, it became disconnected. Although this mechanism is not clear, it is thought that there is a problem with the hole 170 hole opening method. In the figure, 11 is a silicon substrate, and 12 is a silicon oxide film.

The present invention has been made in view of the above-mentioned drawbacks of the conventional method, and aims to obtain good conduction between each layer in a multilayer wiring structure including tungsten as a wiring layer, and to obtain a highly reliable semiconductor device. .

According to the present invention, extremely good conductivity between wiring layers can be obtained by using dry etching such as fluorine-containing gas plasma when forming conductive holes between wiring layers in the electrical insulating film covering the tungsten film.

The present invention particularly includes forming desired P-type and N-type conductive regions on the entire surface of a semiconductor substrate, and at least a tungsten-based layer electrically connected to said substrate. a step of forming a wiring N'(i-), a step of depositing a second electrical insulating film on the first electrical insulating film including the wiring layer, and a step of forming an opening in the second electrical insulating film leading to the wiring layer; forming a hole at least immediately before the surface of the wiring layer is exposed using a gas plasma etching method containing fluorine;
The method of manufacturing a semiconductor device includes a step of forming a metal layer connected to the wiring layer through the opening, and a remaining step.

Next, silicon, which is a semiconductor material, will be used as an example in order to better understand the present invention.

Figure 2 A: Silicon substrate 21 is formed by normal diffusion, etching, etc.
P-type and N-type conductive regions (not shown) are formed on the entire surface of the substrate. Here, the literature (IEEE JOURN
AL OF 5OLIL)-8TATE CL-RCU
ITS, VOL, 8C-13, NO, 5, 0CTOBE
R1978, PP693-697) VC was formed by the PsA method described.

Next, the literature (Solid 5tate Technology
ogy/December 1980 pp>9-82
) is vapor-phase grown to form a tungsten layer 25 on the polycrystalline silicon 24.

FIG. 21B: A silicon nitride film 26 is deposited on the surface of the silicon substrate 21 including the tungsten layer 25 by plasma vapor deposition, and a conductive hole 27 is provided. Opening hole 2
The method for providing 7 uses plasma etching using a gas containing fluorine, such as tetrafluorocarbon (CF4).

FIG. 2C: Next, a metal layer, for example aluminum, is deposited and a metal layer 28 is formed by selective etching.

The yield of the tungsten layer 25 and the aluminum metal (-28) which are electrically conductive through all the openings 27 of the semiconductor device thus obtained is 100%, and the resistance value per opening is approximately 0.5 ohm or less. , which was a practically acceptable value.In the above example, tungsten was grown in a vapor phase, but
It is also possible to use a snow ring.Also, although a plasma vapor grown silicon substrate film was used as an interlayer insulating film to insulate and separate the tungsten layer and the aluminum layer, the present invention is not limited to this.
The silicon oxide film may be deposited by plasma vapor deposition or by a battering method. Further, the plasma etching method used as a method for forming conductive holes includes, in addition to what is generally called plasma etching, reactive ion etching and other redrano etching methods in which etching is performed using gas plasma. The effects of the present invention can be achieved by applying these etching methods at least immediately before the tungsten layer is exposed. The etching method may be applied.

Further, as the second metal layer connected to tungsten j-, similar effects can be expected with aluminum-silicon, aluminum-steel, other aluminum alloys, titanium-platinum-gold, etc. in addition to aluminum. Further, as applicable semiconductor devices, it is applicable to most devices such as bipolar, MOS, and FET.

Although the present invention has been described above with reference to embodiments, the essential part of the present invention is to Alternatively, the openings reaching the layer containing tungsten as a main component are provided by a gas plasma method containing at least fluorine, and the great effect of the present invention is to provide a semiconductor device with high yield and excellent reliability. That's true.

[Brief explanation of the drawing]

Fig. fJ1 is a sectional view of a conventional device, and Fig. 2 is a sectional view of each process showing an embodiment of the present invention. In the figure, 1, 21...silicon, 12, 13, 22゜23...i...silicon oxide film, 14.24...
・Polycrystalline silicon, 15.25...Tungsten, 16...Silicon oxide film, 18.28...
. . . aluminum, 26 . . . silicon nitride film.

Claims (1)

[Claims] A step of completely forming a wiring containing at least Nk mainly composed of tungsten and gold on one main surface of the substrate, and a step of completely forming the wiring containing at least Nk mainly composed of tungsten and gold, and the above-mentioned wiring!
a step of depositing an electrical insulating film on the sea; a step of providing an opening in the i11 insulating film leading to the wiring at least immediately before the surface of the wiring layer is exposed by a plasma etching method containing fluorine; A method for manufacturing a semiconductor device, comprising the step of forming a metal layer connected to the wiring layer through the opening.