JPH05206082A - Production of semiconductor device - Google Patents

Abstract

PURPOSE:To suppress after corrosion and side etching by adding NH3 gas to chloride gas or bromide gas for dry etching for the fine process of wiring material film. CONSTITUTION:A base oxide film 2 is formed on an Si substrate and a wiring film 3 is formed on the base oxide film 2. A mask oxide film 4 is formed on the wiring film 3 so as to be coated with photoresist 5 and patterning is performed. Namely, the mask oxide film 4 on the wiring film 3 is patterned by dry etching and the mask material is formed for the wiring process. After processing the mask oxide film 4, the resist 5 left on the film 4 is removed by 02 gas plasma. Then, dry etching is performed by using the mask oxide film 4 as a mask and adding NH3 gas to bromide gas by 3-40%. Thus, after corrosion and side etching are suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device used in a semiconductor manufacturing process such as an electronic device.

[0002]

2. Description of the Related Art In recent LSI technology, while dry etching has progressed due to miniaturization, an increase in current density has become unavoidable with fine wiring, and an electromigration problem has become apparent. Although Si and Cu were added to Al and a barrier metal was used to improve the reliability of the wiring, many problems associated with these treatments occurred before and after etching.

That is, it is the occurrence of after-corrosion due to the residual resist or Cu. In order to suppress this corrosion, immediately after etching, while heating in a chamber different from the etching chamber, oxygen gas
A method of stripping the resist while adding F ₄ gas or CH ₃ OH gas has been considered.

Further, as miniaturization progresses, the precision required for suppressing side etching is increasing, and for a wiring having a width of 0.25 μm, suppressing side etching of 0.03 μm or less is required.

On the other hand, the use of the stacked capacitor causes a step difference of about 1 μm, and it becomes necessary to form fine wiring in the severe step difference part. In the dry etching in this step portion, a considerable amount of over-etching is performed so as not to leave a residue of the wiring material. However, since a normal photoresist mask has no dry etching resistance, it is 1.5 μm.
The above resist must be used as a mask.

As described above, increasing the thickness of the resist makes it difficult to focus the upper and lower portions of the step at the same time during lithography, and also makes it difficult to expose a fine pattern. Therefore, in order to pattern a fine pattern at the step portion, it is increasingly necessary to thin the photoresist mask and to form a hard mask such as an oxide film having high dry etching resistance under the photoresist mask.

[0007]

In order to suppress the occurrence of after-corrosion due to resist residues or Cu residues after etching, immediately after etching, CF ₄ is added to oxygen gas while heating in a chamber different from the etching chamber, A method of stripping the resist while adding CH ₃ OH gas has been considered, but it is not a sufficient measure,
Corrosion may occur after a few days.

Further, in the conventional photoresist mask,
The side wall of the wiring material could be protected by the carbon polymer of the resist during etching and the side etching could be suppressed.However, when a hard mask such as an oxide film is used, a side wall protecting film is not formed. It causes problems such as easy occurrence.

An object of the present invention is to provide an etching method that solves the above-mentioned conventional problems, suppresses after-corrosion, and suppresses side etching.

[0010]

In order to achieve the above object, a method of manufacturing a semiconductor device according to the present invention is a method of manufacturing a semiconductor device in which a wiring material film is finely processed by dry etching. This is performed by adding NH ₃ gas to chlorine-based gas or bromine-based gas.

[0011]

[Function] In a method of dry etching by adding NH ₃ gas to chlorine-based gas or bromine-based gas, the N component of NH ₃ is shielded from moisture in the atmosphere by nitriding the surface of the wiring film after the treatment. Therefore, it is effective in suppressing after-corrosion and leads to improvement in yield. This effect is effective whether the mask material for wiring processing is a photoresist mask or an oxide film mask.

Further, since the H component of NH ₃ suppresses the generation amount of chlorine or bromine radicals, isotropic etching due to radicals is suppressed and side etching is suppressed.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. A base oxide film 2 is formed on a Si substrate 1 shown in FIG. 1A, and a wiring film 3 (aluminum or aluminum alloy, Cu) is formed on the oxide film 2 by a sputtering method or a CV method.
D (Chemical Vapor Deposition)
on) to form a thickness of 0.5 μm. Further, a mask oxide film 4 is formed on the wiring film 3 by the CVD method,
A normal photoresist 5 is applied on the mask oxide film 4, and is patterned like the resist 5 in a normal photoresist process.

As shown in FIG. 1B, the mask oxide film 4 on the wiring film 3 is patterned by dry etching with CF ₄ and CHF ₃ gas to be used as a mask material for processing the wiring film. After processing the mask oxide film 4, the resist 5 remaining on the film 4 is removed by O ₂ gas plasma.

As shown in FIG. 1C, the mask oxide film 4 is formed.
With a mask, chlorine gas (Cl ₂ , BCl _3, etc.) or
3% NH ₃ gas in bromine gas (HBr, BBr ₃ etc.)
About 40% is added, and dry etching is performed. In the dry etching process of the mask oxide film 4 and the wiring film 3, ECR (Electron CyclotronR) is used.
esonance) or RIE (Reactive)
Ion Etching) device is used.

The patterning of the mask oxide film 4 may be performed by an exposure process using EB (Electron Beam). The mask oxide film 4 is formed by applying a coating type oxide film SOG (Spin On Glass).
s) or a CVD nitride film may be used.

[0017]

As described above, according to the present invention, in the fine processing of a wiring film having a severe step difference, NH ₃ gas is added to chlorine-based gas or bromine-based gas for dry etching. The surface of the film is nitrided and can block moisture from the atmosphere, which is effective in suppressing after-corrosion and improves the yield. Further, suppressing the generation amount of chlorine or bromine radicals has the effect of suppressing isotropic etching and side etching, so that the yield and reliability of the semiconductor device can be improved.

[Brief description of drawings]

1A to 1C are cross-sectional views of a semiconductor chip showing an embodiment of the present invention in process order.

[Explanation of symbols]

 1 Silicon substrate 2 Underlayer oxide film 3 Wiring film 4 Mask oxide film 5 Photoresist film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H01L 21/3205

Claims (1)

[Claims] 1. A method of manufacturing a semiconductor device in which a wiring material film is finely processed by dry etching, wherein the dry etching is performed by adding NH ₃ gas to chlorine-based gas or bromine-based gas. A method of manufacturing a semiconductor device, which is characterized.