JPS60124951A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the disconnection of Al wirings due to corrosion or oxidation by a method wherein an insulation fil or a conductive film coating conductor wirings is left only on both sides of the conductor wirings by anisotropic etching. CONSTITUTION:The Al wirings 2 are formed on a semiconductor substrate 1, and next a PSG (phospho-silicate glass) film 4 is adhered over the whole surface. Then, the film 4 is etched by anisotropic etching and thus left only side surfaces of the wirings 2. A PSG film 5 is adhered again over the whole surface. In such a manner, discontinuous lines do not appear on the film 5, and the wirings 2 are protected by complete coating and then prevented from oxidation.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of forming wiring.

(bl) Prior Art and Problems As is well known, in semiconductor devices such as semiconductor integrated circuits (ICs), semiconductor elements and other elements are formed on the surface of a semiconductor substrate, and aluminum (AI) derived from these elements is formed on the surface of a semiconductor substrate.
Alternatively, a wiring layer made of aluminum silicon (AISi: Si content of 10% or less) is provided on the upper surface. Aluminum is used as wiring because it has high electrical conductivity, strong adhesion to insulating films, is inexpensive, and is easy to pattern.

Figure 1 shows the cross-sectional structure of aluminum wiring.
is a semiconductor substrate, and 2 is an aluminum wiring.

3 is an insulating protective film made of a phosphosilicate glass (PSG) film. In this formation method, first, an aluminum film is deposited to a thickness of about 1 μm by sputtering or vapor deposition, and then a pattern of a resist film made of novolac resin is formed on it. Using this as a mask, chlorine (C12) is applied. Dry etching with system gas or chlorine compound gas to a width of 2 to 3μ
m aluminum interconnections 2 are formed. On the top surface, PS
The G film 3 is deposited by chemical vapor deposition (CVD) or plasma vapor deposition (plasma CVD).

By the way, the dry etching that has been used recently is anisotropic etching, which has the advantage of highly accurate patterning, and the aluminum wiring in the above example can also be formed with high accuracy. However, on the other hand, the side portions of the wiring layer become steep, and sometimes are formed in a reverse tapered shape. On the other hand, the PSG film 3 is coated from all directions, with coverage (
However, as shown in the figure, the boundary between the PSG film grown from the semiconductor substrate 1'' and the PSG film grown from the side of the wiring is discontinuous on the side of the wiring layer.

Therefore, there is a problem in that water and gas easily enter through the boundary line, oxidize the aluminum wiring 2, and eventually become an insulator and cause disconnection.

There are other known causes of disconnection in aluminum wiring, such as disconnection due to mutual leakage current between aluminum wiring.
As a result, disconnection is a phenomenon that occurs when moisture or gas permeates through an insulating protective film to corrode and oxidize aluminum, and such disconnection of aluminum wiring is an important issue from the viewpoint of RC reliability.

(C1 Purpose of Invention 4 Invention No. 1. Al(d) caused by corrosion and oxidation as mentioned above.
l Structure of the Invention The object of the invention is to pattern a conductive wiring on a semiconductor substrate, then grow an insulating film or a conductive film to cover the conductive wiring, and then anisotropically etching the insulating film or conductive film. This can be achieved by a method for manufacturing a semiconductor device, which includes a step of etching a conductive film and leaving the insulating film or conductive film on both sides of the conductor wiring.

tel　Embodiments of the invention Examples will be described in detail below with reference to nine drawings.

2 to 5 show step-by-step cross-sectional views of the forming method according to the present invention. In FIG. In this figure, an aluminum wiring 2 having a width of 2 to 3 μm is formed, and the formation method is the same as the J method described above. Next, as shown in Figure 3, a film thickness of several thousand layers (
A psc film 4 of 0.2 to 1 μm) is deposited. If it is deposited from all directions using the CVD method, the coverage will be good (and the corner bones on the sides of the aluminum wiring 2 will be sufficiently filled in. In that case, a boundary line will appear on the side of the aluminum wiring 2 as described above). Needless to say.

Next, as shown in FIG. 4, the entire PSG film is anisotropically
- Etching is performed by notching (tri-etching) to leave PSGllW4 only on the side surfaces of the aluminum wiring 2. The etching agent is trifluoromethane (CIIF
3) and tetrafluoromethane (C1i4) is used. When etching the aluminum wiring uniformly from the surface, apply P only to the sides of the aluminum wiring that is sufficiently thickly coated.
It is possible to leave the SG film 4.

Thus, by controlling the thickness of the PSG film 4, it is possible to adjust its remaining amount.

Further, in the case of an insulating film such as a PSG film, the amount of etching is also controlled, and it is not necessarily necessary to completely remove the PSG film 4 on the plane.

Next, as shown in FIG. 5, a PSG film 5 with a thickness of several thousand layers is deposited again by the CVD method. In this case, discontinuous lines do not appear in the PSG film 5, and the aluminum wiring 2
This completely covers and protects the aluminum wiring, preventing oxidation of the aluminum wiring.

Next, FIGS. 6 to 8 are process-order sectional views of another embodiment according to the present invention. In this example, as shown in FIG.
The O7 aluminum film 12, which has a thickness of about 1000 layers, is broken again using the sputtering method or the Art Ministry method. Then, as shown in FIG. 7, aluminum It! The entire surface of the aluminum wiring 12 is etched by anisotropic etching, leaving the -r aluminum film 12 only on the side surfaces of the aluminum wiring 2. The etching agent is a chlorine (CI2) gas or a chlorine compound gas.

Next, as shown in FIG. 8, PSG was formed by CVD method.
When the film 13 is deposited, the PSG film 13 has no discontinuities and the aluminum wiring 2 is completely covered and protected. In this example, the same conductive film as the wiring layer is formed on the wiring (y-q plane), but the conductive film is not limited to aluminum, and instead of the aluminum film 12, a phosphorus-doped polycrystalline silicon film is sputtered. carbon tetrachloride (
CC14) -1i gas may be used for dry etching, or a metal such as tungsten may be used.

Furthermore, the insulating protective film is not only a PSG film, but also a plasma CV film.
The same result can be obtained even if a silicon nitride (SiN) film or a silicon oxynitride (SfON) film deposited by the D method is used.

(f) Effects of the Invention As is clear from the above description, the present invention prevents disconnection of aluminum wiring and significantly contributes to higher reliability of ICs.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional structural view of a conventional aluminum wiring, and FIGS. 2 to 5 and 6 to 8 are step-by-step cross-sectional views of a forming method according to the present invention. In the figure, 1 is a semiconductor substrate and 2 is an aluminum wiring. 3.4 and 5.13 are PSG films, and 12 is an aluminum film. Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 Leap Figure 7 Figure 8

Claims (1)

[Claims] A conductor wiring is patterned on a semiconductor substrate, and then an insulating film or a conductive film is grown to cover the conductor wiring, and then the insulating film or conductive film is etched by anisotropic etching to remove the conductor wiring. A method for manufacturing a semiconductor device, comprising the step of leaving the insulating film or the conductive film on both sides.