JPH05347306A - Aluminium group wiring and formation thereof - Google Patents

Abstract

PURPOSE:To allow tapered processing of an Al group wiring without affecting a size conversion difference in order to improve coverage of an interlayer film in a multilayer process. CONSTITUTION:A lower layer Al group film 3 and an upper layer Al group film 4 are piled up. Since the upper layer Al group film 3 contains no Si and the lower layer Al group film contains no Si, an undercut is generated on the upper layer Al group film 4 at the time of dry etching while forming a tapered Al group wiring. Thereby, coverage of an interlayer film is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and aluminum-based wiring used in its manufacturing process,
Particularly, it relates to a wiring forming method for achieving taper processing of aluminum-based wiring.

[0002]

2. Description of the Related Art As seen in VLSI, ULSI, etc. in recent years, with the progress of high integration and high performance of semiconductor devices, the wiring portion occupies on the device chip. Although the percentage tends to increase, multilayer wiring is now an indispensable technology in order to prevent a large increase in chip area due to this. As a technique for improving the coverage of the interlayer insulating film in this multilayer wiring process and favorably forming the multilayer wiring,
There is a taper etching technique for l wiring. Among this taper etching technology, methane trichloride (C
A method of obtaining a taper shape by adding a deposition gas such as HCl ₃ (Arimon et al. 1986 Dry Process Sym
Posium Proceedings (2) -4, the method described on page 48) is well known. However, in this method, deterioration of the particle level due to addition of a deposition gas in the etching process and the final Since the taper shape is thicker than the mask width, it cannot be applied to a fine pattern having a narrow line / space interval.

The present invention was devised in view of such conventional problems, and enables taper processing of an Al-based film without affecting a dimensional conversion difference and the like, and a multilayer wiring process. To obtain an aluminum-based wiring and a method of forming the same for improving the coverage of the interlayer film in the above.

[0004]

Therefore, the invention according to claim 1 is to solve the problem that the silicon content decreases from the lower part to the upper part of the wiring layer, and the invention according to claim 2 particularly , A lower layer made of an aluminum-based metal containing silicon (Si) and an upper layer made of an aluminum-based metal not containing silicon.

According to the third aspect of the present invention, a lower layer made of an aluminum-based metal containing silicon and an upper layer made of an aluminum-based metal not containing silicon are sequentially formed on the barrier metal layer and then processed by dry etching. It is characterized by

According to a fourth aspect of the present invention, the step of forming a lower layer made of an aluminum-based metal containing silicon, the step of forming an upper layer made of an aluminum-based metal not containing silicon on the lower layer, and the upper layer A step of forming an antireflection film on the antireflection film, a step of forming a resist pattern on the antireflection film, and a step of etching the antireflection film so that an undercut occurs in the antireflection film under the resist pattern, The method is characterized by including a step of dry etching the upper layer and the lower layer.

[0007]

According to the present invention, when the Al-based film is formed in advance,
By forming the l-based film into a two-layer structure with or without Si contained, an undercut is provided only in the upper Al part with good controllability, and a tapered shape is achieved. Here, the Al-based film having a two-layer structure is based on the knowledge about the etching conversion difference depending on the film quality of Al, which was reported at the Japan Society of Applied Physics (Kabuchi et al., 1992 Autumn Bibliographic Proceedings, 9P). -ZF-15,
P515). According to the above-mentioned announcement, a large undercut is generated in the Al film without Si addition in the Al alloy. Although the detailed mechanism is unknown, the conductivity of the oxide film on the side wall formed during etching is higher in Al without Si addition, which facilitates the exchange of electrons necessary for etching and promotes the reaction on the side wall. It is thought that this is because it becomes easier. According to the present invention, an Al alloy film without Si addition, which facilitates the reaction on the side wall, is used as an upper layer.
If a two-layer structure with the added Al alloy film as the lower layer is adopted,
Since it is possible to insert an undercut with good controllability only in the upper Al-based film, the lower Al is anisotropically processed.
A good Al film that has just been chamfered can be realized without specially devising process conditions.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the aluminum-based wiring and the method for forming the same according to the present invention will be described below with reference to the embodiments shown in the drawings.

1A to 1C show a first embodiment of the present invention.
FIG.

First, in this embodiment, as shown in FIG. 1A, a titanium (Ti) film 2A and a titanium oxynitride (TiO) are formed on an interlayer insulating film 1 formed on a semiconductor substrate.
N) The barrier metal layer 2 having a laminated structure of the film 2B is formed.
Incidentally, the titanium film 2A and the titanium oxynitride film 2B
The film forming conditions are as follows, for example. The titanium film 2A and the titanium oxynitride film 2B were formed by using a multi-chamber type DC magnetron sputtering apparatus.

(Titanium film 2A film forming (sputtering) conditions) Target: Ti O Gas and its flow rate Argon (Ar) 40 _SCCM O Pressure 0.67 Pa DC power 4 KW Substrate temperature 150 ° C O Film Thickness: 30 nm (deposition of titanium oxynitride film 2B (sputtering)
Conditions) ○ Target ... Ti ○ Gas and its flow rate Ar-60% N ₂ ... 40 _SCCM ○ Pressure ... 0.67 Pa ○ DC power ... 8 KW ○ Substrate temperature ... 150 ° C ○ Film thickness ... 70 nm In this way, barrier metal layer 2 After forming, the lower layer Al-based film 3 and the upper layer Al-based film 4 are formed thereon by using the multi-chamber type DC magnetron sputtering apparatus. The lower Al-based film 3 is formed of Al-0.5% Cu-
It is a film having a composition of 1% Si and containing silicon (Si). The upper Al-based film 4 has a composition of Al-0.5% Cu and is a film containing no silicon (Si).

(Film (sputtering) conditions for the lower layer Al-based film 3) Target: Al-0.5% Cu-1% Si ○ Gas and its flow rate Argon (Ar) 40 _SCCM ○ Pressure 0.66 Pa ○ DC Electric power: 10 kW ○ Substrate temperature: 150 ° C. ○ Film thickness: 200 nm (Conditions for forming (sputtering) the upper Al-based film 4) ○ Target: Al-0.5% Cu ○ Gas and its flow rate Al: 40 _SCCM ○ Pressure: 0.67 Pa ○ DC power ... 10 kW ○ Substrate temperature ... 150 ° C. ○ Film thickness ... 200 nm Next, using an amorphous silicon (a-Si) film 5 as an antireflection film using the same multi-chamber type DC magnetron sputtering device, The layers are stacked under the film forming conditions shown below.

(Conditions for forming (sputtering) the amorphous silicon film 5) Target: a-Si ○ Gas and its flow rate Ar: 40 _SCCM ○ Pressure: 0.67 Pa ○ DC power: 4 kW ○ Substrate temperature: room temperature ○ Film thickness 30 nm Next, a resist (for example, TSMR-V3 type resist) is applied on the amorphous silicon film 5 and patterned to form a resist pattern having the same width as the wiring width to be formed, as shown in FIG. 6 is formed.

Thereafter, using the resist pattern 6 as a mask, the amorphous silicon 5 film was etched by the first stage etching, and then the upper layer Al-based film 4 and the lower layer Al-based film 5 were etched by the second stage etching. A magnetic field microwave plasma etcher is used for these etchings, and the respective etching conditions are as follows. The amorphous silicon film 5 is
In the first stage etching, as shown in FIG. 1B, etching is performed with an undercut.

(Etching in the first step) Gas and its flow rate Sulfur hexafluoride (SF ₆ ) ... 50 _SCCM ○ Pressure ... 10 mTorr (1.3 Pa) ○ Wave power ... 850 W ○ RF bias ... 50 W (Second step) etching) ○ gas and its flow rate of boron trichloride (BCl ₃₎ ... 60 _SCCM chlorine (Cl ₂₎ ... 90 _SCCM ○ pressure ... 16mTorr (1.5Pa) ○ μ-wave power ... 850W ○ RF bias ... 50W (2MH _Z) By such second-stage etching, an Al-based wiring having a tapered upper portion as shown in FIG. 1C can be formed. This is because the upper Al-based film 4 does not have Si, so the conductivity of the oxide film on the side wall formed during etching is increased, and the exchange of electrons necessary for etching is facilitated, so that the etching reaction on the side wall is prevented. It is thought that this is because it is easy to proceed.

Further, since the amorphous silicon film 5 is undercut and narrowed in width in the first-stage etching, a gap is formed between the resist pattern 6 and the upper Al-based film 4, and radicals are generated from this space. Since it penetrates, there is an advantage that the tapered shape can be processed more easily.
Since the lower Al-based film 3 contains Si,
Anisotropically processed, good wiring with no size conversion difference is obtained.

(Embodiment 2) In this embodiment, a TiON film is used as an antireflection film.

As shown in FIG. 2, after forming the upper layer Al-based film 4 by the same method as in the first embodiment, the TiON film 7 is formed.
Is formed by the DC magnetron sputtering method under the following film forming conditions.

(Conditions for forming (sputtering) the TiON film 7) Target: Ti ○ Gas and its flow rate Ar-60% N ₂ … 40 _SCCM ○ Pressure… 0.67 Pa ○ DC power… 8 kW ○ Substrate temperature… 150 ° C. O Film thickness ... 70 nm After that, a resist pattern 6 is formed, and the above-mentioned Example 1 is performed.
Etching was performed under the following conditions using the same apparatus as described above.

(Etching conditions) ○ Gas and its flow rate Boron trichloride (BCl ₃ ) ... 60 _SCCM Chlorine (Cl ₂ ) ... 90 _SCCM ○ Pressure… 16 mTorr (1.5 Pa) ○ μ-wave power… 850 W ○ RF bias… 50 W (2MH _Z ) In this embodiment, as in the case of the above-described Embodiment 1, the upper Al-based film 4 not containing silicon is undercut as shown in FIG. 3, but is etched from the TiON film 7 in one step. Therefore, the shape becomes like a canopy between the TiON film 7 and the upper Al-based film 4.

Next, the resist pattern 6 is stripped using an inline asher (FIG. 4), and the substrate is returned to the chamber of the magnetic field microwave etcher again to remove the eaves-shaped TiON film 7. Process under the conditions.

○ Gas and its flow rate Sulfur hexafluoride (SF ₆ ) ... 50 _SCCM Oxygen (O ₂ ) ... 10 _SCCM Argon (Ar) ... 40 _SCCM ○ Pressure ... 10 mTorr (1.3 Pa) ○ μ wave power ... 850 W ○ This RF bias ... 50W (2MH _Z), as shown in FIG. 5, a reflection preventing film T
Since the iON film 7 is removed, it is possible to form a good Al-based wiring that is tapered.

Although the respective embodiments have been described above, the present invention is not limited to these, and various design changes associated with the gist of the configuration can be made.

For example, both of the above-mentioned embodiments have a two-layer structure in which the Al-based wiring has the lower Al-based film 3 and the upper Al-based film 4.
It may have a multilayer structure of three or more layers. In this case, the Si content may be reduced toward the upper layer.

Further, of course, the structure may be such that the Si content is continuously reduced.

Although Al-0.5% Cu is used as the Al-based metal in both of the above-described embodiments, an alloy of Al and another element may be used as a matter of course.

[0027]

As is apparent from the above description, according to the aluminum-based wiring and the method for forming the same of the present invention,
Since it is possible to form wiring with a good taper shape,
This has the effect of improving the coverage of the interlayer insulating film formed on the wiring.

Further, since the lower layer of the Al-based wiring is Al containing Si, an undercut does not occur due to etching, and there is an effect that good characteristics can be secured without being affected by a dimensional conversion difference or the like.

[Brief description of drawings]

1A to 1C are cross-sectional views of a main part showing a process of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part showing a process of a second embodiment of the present invention.

FIG. 3 is a sectional view of a key portion showing a step of a second embodiment of the present invention.

FIG. 4 is a sectional view of a key portion showing a step of a second embodiment of the present invention.

FIG. 5 is a sectional view of a key portion showing a step of a second embodiment of the present invention.

[Explanation of symbols]

 2 ... Barrier metal layer 3 ... Lower layer Al-based film 4 ... Upper layer Al-based film 5 ... Amorphous silicon film (antireflection film) 6 ... Resist pattern 7 ... TiON film (antireflection film)

Claims (4)

[Claims] 1. An aluminum-based wiring characterized in that the silicon content decreases from the lower part to the upper part of the wiring layer. 2. An aluminum-based wiring having a two-layer structure of a lower layer made of an aluminum-based metal containing silicon (Si) and an upper layer made of an aluminum-based metal not containing silicon. 3. A barrier metal layer, on which a lower layer made of an aluminum-based metal containing silicon and an upper layer made of an aluminum-based metal not containing silicon are sequentially formed,
A method for forming an aluminum-based wiring, characterized by being processed by dry etching. 4. A step of forming a lower layer made of an aluminum-based metal containing silicon, a step of forming an upper layer made of an aluminum-based metal not containing silicon on the lower layer, and forming an antireflection film on the upper layer. A step of forming a resist pattern on the antireflection film, and etching the antireflection film so that an undercut occurs in the antireflection film under the resist pattern, and dry etching the upper and lower layers. A method of forming an aluminum-based wiring, comprising: