JPS62108542A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To equalize the film thickness of an upper layer wiring by forming an inter-layer insulating film onto a base body so as to coat a lower-layer metallic wiring and an insulating film for smoothing a stepped section remaining on the side wall section of the lower-layer metallic wiring and shaping the upper-layer metallic wiring onto the inter-layer insulating film. CONSTITUTION:An insulating film 2 consisting of phosphorus glass is formed onto a semiconductor substrate 1 and an upper surface is flattened, a first-layer metallic wiring 3 is shaped onto the upper surface, and an silicon nitride film 6 as an insulating film for smoothing a stepped section is formed onto the insulating film 2, including the upper section of the first-layer metallic wiring 3. RIE is executed from the whole upper surface of the silicon nitride film 6 to leave the silicon nitride film 6 so as to shape a frame in a tapered manner only on both side surface sections of the first-layer metallic wiring 3. An silicon nitride film 4 is formed onto the whole upper surface and the surface is smoothed, and a second-layer metallic wiring 5 is shaped onto the film 4. Accordingly, disconnections at stepped sections in the wirings and short circuits are reduced, thus improving yield while forming the upper-layer metallic wiring in uniform film thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a highly integrated semiconductor device having multiple levels of wiring.

[Conventional technology]

FIG. 2 is a cross-sectional view showing the structure of two-layer wiring of a conventional semiconductor device. In the figure, (1) is a semiconductor substrate, (2) is an insulating film, (3) is a first-layer metal wiring, and (4) ) is an interlayer insulating film, and (5) is a second layer metal wiring.

That is, in a conventional semiconductor device, a semiconductor substrate (1)
After flattening the upper surface with an insulating film (2) made of phosphosilicate glass film (PSG), a first layer metal wiring (3) made of Aj' is formed, and a plasma silicon nitride film is formed as an interlayer insulating film (4). A two-layer wiring was constructed by stacking elementary films and forming a second layer metal wiring (5) made of Al on top of the layers.

[Problem that the invention seeks to solve]

The conventional semiconductor device is configured as described above, and the first
The second layer metal wiring layer is subsequently formed on top of this while leaving the extreme unevenness caused by the layer metal wiring.
Fine patterning becomes difficult, leading to problems such as breakage or short circuits in the wiring, or a reduction in film thickness at stepped portions, resulting in poor reliability.

This invention was made in order to solve the above-mentioned problems, and it is possible to eliminate the occurrence of disconnections and short circuits in the wiring in a multi-layer wiring structure, and also to make the film thickness of the upper layer wiring uniform. The purpose of the present invention is to obtain a method for manufacturing a semiconductor device that can perform the following steps.

[Failure to solve the problem]

In the method of manufacturing a semiconductor device according to the present invention, after forming the lower layer wiring, the wiring is framed with an insulating film and tapered, and then the upper layer wiring is formed after forming an interlayer insulating film.

[Effect]

In the method for forming multi-layer wiring in this invention, after forming the lower layer wiring, an insulating film is framed and tapered.
As a result, extremely sharp unevenness is eliminated and smoothed, and the upper layer wiring can be formed in a good shape.

〔Example〕

FIGS. 1A to 1E are cross-sectional views showing the main process steps of a method according to an embodiment of the present invention, and the same reference numerals as in the conventional example in FIG. 2 indicate equivalent parts.

First, an insulating film (2) made of phosphorous glass is formed on the semiconductor substrate 5 by the atmospheric pressure OVD method to flatten the upper surface, and then a first layer metal wiring (3) is formed on it (see FIG. 1A). ).

Next, an insulating film (2) is formed, including on the first layer metal wiring (3).
A silicon nitride film (6) is formed as an insulating film for smoothing the stepped portion by plasma CVD method (Fig. 1B).Next,
Active ion etching (R process E) is applied to the entire upper surface of the silicon nitride film (6), leaving the silicon nitride film (6) tapered and framed only on both side surfaces of the first layer metal wiring (3). (Figure 1C). Next, a silicon nitride film (4) as an interlayer insulating film is formed on the entire upper surface using an envelope plasma CVD method to achieve surface smoothness (Fig. 1D). Wiring (5
) (FIG. 1E) In the above embodiment, a silicon nitride film was used as the insulating film for smoothing the stepped portion and the interlayer insulating film, but any film may be used as long as it fulfills the interlayer insulating function. Further, in the above embodiment, the first # wiring and the second layer wiring thereon have been described, but the present invention can be applied to any two consecutive layers of multilayer wiring.

〔Effect of the invention〕

After the lines are formed, an insulating film is framed, and this insulating film is tapered to smooth the upper surface of the interlayer insulating film formed on top of it, and then the upper layer metal wiring is formed. This has the effect of reducing wiring breaks and short circuits, improving fractionation, and forming upper layer metal wiring with a uniform film thickness, thereby improving foam reliability.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the main process steps of a method according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the structure of a two-layer wiring of a conventional semiconductor device. In the figure, (1) is the semiconductor substrate, (3) is the lower layer (first
(4) is an interlayer insulating film, (5) is an upper layer (#2) metal wiring, and (6) is an insulating film for smoothing the stepped portion. In addition, the same symbols in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) When manufacturing a semiconductor device having multiple layers of wiring, a lower metal wiring is formed on a base, an insulating film for smoothing the stepped portion is formed on the base so as to cover the lower metal wiring, and this After reactive ion etching or the like is applied to the step smoothing insulating film from above and leaving it only on the side wall of the lower metal wiring, the step smoothing insulating film remains on the lower metal wiring and its side wall. 1. A method of manufacturing a semiconductor device, comprising forming an interlayer insulating film on the base so as to cover the substrate, and forming an upper layer metal wiring on the interlayer insulating film.