JP2659980B2 - Method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a technique for forming a taper angle required for fine contacts on an insulating film.

(Prior art) At present, contact holes are formed in a multilayer wiring process by:
As shown in FIG. 6, the interlayer insulating film formed on the first layer wiring is formed by anisotropically etching by RIE (reactive ion etching). By forming a second layer wiring through this contact hole,
The continuity between the second-layer wiring and the first-layer wiring is established.

However, according to this technique, when the contact hole becomes smaller, a second layer wiring (for example,
(Al wiring) cannot be completely inserted, and the Al wiring may be disconnected.

Therefore, as shown in FIG. 6, the insulating film on the upper side of the contact hole is isotropically etched to form a taper angle so that the Al wiring does not break or the Al wiring cannot enter the bottom of the contact hole. We are taking measures. As a method of forming a taper angle on the insulating film above the contact hole, wet etching or CDE (chemical dry etching) is used using a patterned resist as a mask.

However, in the case of a fine contact hole, there arises a problem that the wet etching solution cannot sufficiently enter the opening of the resist and a required taper angle cannot be obtained. This is due in part to the fact that the resist is hydrophobic to the wet etchant. In particular, since the contact hole forming pattern has a high resist coverage, this problem is enhanced. In addition, when the contact hole becomes a fine contact hole (that is, a fine resist opening), the resist scum tends to remain at the bottom of the resist opening, and this problem becomes more conspicuous.

(Problems to be Solved by the Invention) An object of the present invention is to provide a method of manufacturing a semiconductor device capable of forming a required taper angle in a fine contact hole.

[Constitution of the Invention] (Means for Solving the Problems) The present invention provides an insulating film having a resist in which a contact hole is to be formed, formed on a surface thereof by sputtering etching using a freon-based or argon-based gas. And etching isotropically by wet etching to form a taper angle, and then anisotropically etching the insulating film using a resist as a mask.

(Operation) According to the present invention, the resist scum remaining at the bottom of the fine resist opening can be etched by freon-based or argon radical sputter etching, and furthermore, irregularities can be formed on the insulating film. For this reason, the wettability of the insulating film is improved, and the wet etchant sufficiently enters the interface between the resist opening and the insulating film.

Embodiment An embodiment of the present invention will be described with reference to FIGS.

First, a Si substrate (1), for example, a P-type substrate having a plane orientation of 100 is prepared, and a thermal oxide film (2) is formed and a first Al
(3) Deposit (for example, 80 nm). Next, the first Al
(3) A resist is formed on the surface and patterned by a photo-engraving process. RIE using this resist pattern as a mask
After the first Al (3) is etched to remove the resist pattern, the insulating film (4) is deposited and a flattening step of the insulating film (4) is performed. Then, a resist is formed on the surface of the insulating film (4), and the resist in the portion where the contact hole is to be formed is removed to form an opening.

Next, the resist scum (7) remaining at the bottom of the opening of the resist can be removed by, for example, sputter etching using a freon-based gas. Further, the exposed insulating film can be made to have a surface shape (6) with irregularities (see FIG. 2).

Subsequently, the insulating film (4) is etched with a wet etching solution using the resist (5) as a mask.
Can be etched isotropically, so that a taper angle can be formed (see FIG. 3).

Since the portion to be wet-etched has an uneven shape, the wet-etching solution has good wettability, and the wet etching solution can sufficiently enter even if the resist opening is fine.

Thereafter, if the insulating film (4) is etched anisotropically using the resist as a mask, for example, using reactive ion etching (RIE), a contact hole having a taper angle is formed (see FIG. 3).

Next, after the second Al wiring is sputtered on the contact hole, the second Al wiring is patterned by using a resist formed in a predetermined shape in a photo engraving process as a mask, and the resist is removed (see FIG. 4). .

[Effects of the Invention] According to the present invention, the wettability between the insulating film and the wet etchant is improved because the surface of the insulating film at the opening of the resist is uneven before the wet etching for forming a taper angle on the insulating film. It's getting better. For this reason, the wet etching solution easily enters the interface between the resist and the insulating film from the resist opening, and the insulating film can be easily etched. Therefore, even in a fine contact hole, a taper angle required for preventing disconnection of a wiring can be formed in an insulating film, which is suitable for high integration.

[Brief description of the drawings]

1, 2, and 3 are cross-sectional views illustrating a method of manufacturing a semiconductor device according to the present invention. FIG. 4 is a cross-sectional view of a semiconductor device obtained according to the present invention. Is a sectional view showing a conventional example. In the figure, 1 ... Si substrate, 2 ... Thermal oxide film 3 ... First Al wiring, 4 ... Insulating film 5 ... Resist 6 ... Insulating film surface with unevenness 7 ... Second Al wiring

Claims (2)

(57) [Claims] A step of forming a first-layer wiring on a semiconductor substrate; a step of depositing an insulating film on the first-layer wiring; A step of forming an opening by removing a resist in which a contact hole is to be formed by an embossing step; After the treatment, a step of isotropically etching a part of the insulating film near an opening of the resist with a wet etchant; a step of forming a contact hole by reactive ion etching in the resist mask; Forming a second-layer wiring connected to the first-layer wiring via a semiconductor device. 2. The method according to claim 1, wherein the portion where the contact hole is to be formed is 2.0.
2. The method for manufacturing a semiconductor device according to claim 1, wherein the thickness is not more than μm.