JPH04199514A - Manufacture of semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To highly accurately etch a fine pattern by dry-etching with a porous metal film as a mask and patterning a film to be etched. CONSTITUTION:A film 2 to be etched comprising an Si oxide film, an Si nitride film, a polycrystalline Si film or a plurality of these layers is on a semiconductor substrate 1, while a porous metal film 3 is high melting point metal such Ti, TiN, W, their silicide or nitride, or compound in the high melting point metal, which is formed entirely on the film 2 to be etched by means of sputtering, etc. The film 2 is dry-etched with the porous metal film 3 as an etching mask. Thus no ion reflection occurs on the etching mask, so that dry etching conforming to the mask pattern is performed and highly accurate fine processing is possible.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor integrated circuit device, and in particular, when dry etching such as RIE is performed, it is possible to perform high-precision fine etching that is faithful to a mask pattern. The present invention relates to a method for manufacturing a semiconductor integrated circuit device that can be processed.

[Conventional technology]

FIG. 2 is a sectional view showing a conventional method for manufacturing a semiconductor integrated circuit device. 1 is a semiconductor substrate, and 2 is a film to be etched, which may be, for example, a Si oxide film, a Sj nitride film, a polycrystalline Si film, or the semiconductor substrate 1 itself. 5 is a photoresist, and after forming the film to be etched 2, a desired photoresist pattern 5 is formed through a normal photolithography process.

After this, RI E (Reactive Jon Et
Using the photoresist pattern 5 as a mask, the film to be etched 2 is patterned by dry etching such as etching.

When patterning the photoresist 5, the side walls of the resist pattern were wavy because standing waves were generated due to interference between the light incident on the photoresist 5 and the light reflected from the interface between the photoresist 5 and the film to be etched 2. It becomes the shape. Since the dimensions of the etching pattern are determined by the dimensions of the bottom of the resist pattern, this waving of the sidewalls of the resist pattern leads to a deterioration in the dimensional controllability of the bottom of the resist pattern, which leads to instability of the dimensions of the bottom of the etching pattern. means. Normally, the resist is baked to suppress such undulating shapes. As a result, the side walls of the resist pattern 5 have a smooth shape, and dimensional controllability is also greatly improved.

However, in dry etching such as RIE,
Ions, which are the etching species, are reflected from the smooth side walls of the resist pattern, and the etched film 2 has a distorted shape as shown in FIG.

That is, the ions 4' that are perpendicularly incident on the semiconductor substrate are incident on the side walls of the resist pattern 5 without being reflected, and the etching progresses faithfully to the resist pattern.

However, the ions 4 incident on the semiconductor substrate at a certain angle θ are reflected by the side walls of the resist pattern 5, and then proceed to etch the film to be etched 2. by this,
The film to be etched 2 under the resist pattern 5 is also etched, and the shape after etching becomes a distorted shape as shown in FIG.

Furthermore, as shown in FIG. 3, in conventional etching using the photoresist 5 as a mask, charge concentration occurs due to ions incident on the photoresist film 5 as etching progresses, and the area where the photoresist 5 is located on the substrate is concentrated. A local electric field 6 is generated nearby. As a result, the direction of the ions 4 incident on the substrate is bent by the electric field 6 generated near the photoresist 5, so that the etched shape is distorted.

In this way, in the conventional example, deterioration of the etching shape due to the ions 4 incident on the semiconductor substrate 1 at a certain angle is unavoidable, and especially when etching a fine pattern, it deteriorates device precision, leading to a decrease in yield and This caused a major problem, leading to deterioration in reliability.

This invention was made to solve the above problems, and allows fine patterns to be etched with high precision.
An object of the present invention is to provide a method for manufacturing a semiconductor integrated circuit device that can improve yield and device reliability.

[Means to solve the problem]

In the method of manufacturing a semiconductor integrated circuit device according to the present invention, a film to be etched is etched by dry etching using a porous metal film as an etching mask.

[Effect]

In the present invention, since a porous metal film is used as an etching mask when dry etching a film to be etched, there is no reflection of ions from the etching mask, and dry etching can be performed faithfully to the mask pattern.
High-precision microfabrication becomes possible.

〔Example〕

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

FIG. 1 is a cross-sectional structural diagram showing a method of manufacturing a semiconductor integrated circuit device according to the present invention. In the figure, 1 is a semiconductor substrate,
Reference numeral 2 denotes a film to be etched, which is, for example, a Si oxide film, a Si nitride film, a polycrystalline Si film, or a multilayer film composed of a plurality of these layers. 3 is a porous metal film that serves as an etching mask when etching the film to be etched; for example, T
i, TiN, W, WS i, MoS i, Ta
, TaSi.

It is a high melting point metal such as TiW, its silicide or nitride, or a compound between high melting point metals, and is formed on the entire surface of the film to be etched 2 by, for example, a sputtering method or a CVD method.

Thereafter, a desired resist pattern is formed by a normal photolithography process, dry etching such as RIE is performed, and the resist is removed. At this time, the film thickness of the porous metal film 3 depends on the etching selectivity when etching the film to be etched 2, but is usually 20
A film thickness of about 0.00 to 3000 or less is sufficient. Also,
Since etching of the porous metal film 3 is performed using a photoresist as a mask, is there any deterioration of the etched shape due to reflection of ions on the side walls of the resist, as in the case of the conventional example, and the film thickness of the porous metal film 3? Since it is relatively thin (about 2,000 to 3,000 people), there is no major deterioration of the shape, and a desired pattern can be obtained just like the photoresist pattern.

RIE is performed using the pattern of the porous metal film 3 thus formed as a mask, and the film to be etched 2 is etched. At this time, a certain angle (θ) with respect to the substrate surface
The ions 4 that enter the porous metal film with a . Therefore, the adverse effect of the ions 4 incident from an oblique direction on the etching shape is reduced, and highly accurate etching is possible.

Furthermore, since the etching mask 3 is a metal film, unlike when using a conventional photoresist film, there is no concentration of charge (charge-up) on the etching mask, so no electric field is generated near the middle of the etching mask. ,
The effect on the directionality of ions, which are the etching species, is small, and etching progresses only with ions that are incident perpendicularly to the substrate, so high-precision processing is also possible from this point of view.

〔Effect of the invention〕

As described above, according to the present invention, since a porous metal film is used as an etching mask during dry etching such as RJE, the reflection of ions at the sidewalls of the mask is reduced, and the mask pattern is This has the effect of enabling faithful and highly accurate etching. In addition, since there is no concentration of charge in the etching mask and therefore no local electric field is generated, etching progresses only with ions that are incident perpendicularly to the substrate, making it possible to perform highly accurate etching. This has the effect of improving yield and making it possible to manufacture highly accurate and highly reliable semiconductor integrated circuit devices.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a method for manufacturing a semiconductor integrated circuit device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a method for manufacturing a semiconductor integrated circuit device in a conventional example, and FIG. 3 is a problem with the conventional example. It is a sectional view showing a point. In the figure, 1 is a semiconductor substrate, 2 is a film to be etched, and 3 is a semiconductor substrate.
is the porous metal film, 4 is the angle (θ) with respect to the semiconductor substrate
4° is the ion incident perpendicularly to the semiconductor substrate, 5 is the photoresist mask, and 6 is the electric field. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A method for manufacturing a semiconductor integrated circuit device in which elements are formed on a semiconductor substrate, characterized in that dry etching is performed using a porous metal film as a mask, and the film to be etched is patterned. Method of manufacturing the device. (2) Claim 1, wherein the porous metal film is a high melting point metal film, a silicide of a high melting point metal film, a nitride of a high melting point metal film, or a high melting point intermetallic compound.
A method of manufacturing the semiconductor integrated circuit device described above.