JPH08111401A - Method for patterning laminated wiring - Google Patents

Abstract

(57) [Summary] [Objective] Anisotropic etching is performed on a laminated wiring in which an Al-based metal layer is formed on a W layer and which has excellent migration resistance, without causing side etching or particle contamination. [Structure] After etching the Al-based metal layer 5 with a Br-based gas, the refractory metal layer 4 is patterned by switching to a mixed gas of Cl-based and O-based. A passivation treatment may be performed on the side surface of the Al-based metal layer 5 pattern. [Effect] Since the side surface of the Al-based metal layer 5 pattern is covered with the strong side wall protective film 8a containing Br, the refractory metal layer 4 is formed.
Side etching does not occur during etching. Further, since the F-based gas is not used, the side wall protective film 8a is made of AlF _x.
It does not remain as a fence-like residue of the system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of patterning a laminated wiring used for an internal wiring of a semiconductor device or the like, and more specifically, a patterning of a laminated wiring including a structure in which an Al-based metal layer is formed on a refractory metal layer. Regarding the method.

[0002]

2. Description of the Related Art The degree of integration of semiconductor devices such as LSIs has increased,
As the design rule is scaled down from the sub-half micron level to the quarter micron level, the pattern width of the internal wiring is being reduced. Conventionally, low-resistance Al and Al-based alloys have been often used as internal wiring materials. However, such reduction in wiring width causes disconnection due to electromigration or stress migration, which causes a serious problem in device reliability. It has become to.

As one of the countermeasures against such various migrations, like Al-Cu and Al-Si-Cu,
Methods such as alloying with a low resistance metal such as Cu or stacking with a barrier metal such as TiN are adopted. Further, in recent years, as a more effective wiring structure, a high-rigidity wiring layer, such as a refractory metal such as W, Mo, or Ta, or an alloy or compound thereof, which can secure a certain degree of conductivity, and has a high rigidity is formed below the Al-based metal layer. The formed laminated wiring is being studied. A refractory metal such as W has significantly higher electromigration resistance than an Al-based metal. It has been reported to and is widely known. However, since the electric resistance of W is higher than that of Al, an increase in wiring resistance and a decrease in signal propagation speed can be seen in a single layer. Therefore, even if both are combined, even if the low resistance Al-based metal layer is broken, the lower layer The presence of the refractory metal layer of
It is based on the idea that disconnection can be avoided in the wiring layer as a whole by utilizing the redundancy effect. In particular, when W is used, it is a material having a relatively low resistance among refractory metals, and since a film formation method by blanket CVD has been established, it is expected as a highly reliable laminated wiring structure in the future. .

[0004]

However, in patterning a laminated wiring including a structure in which an Al-based metal layer is formed on a refractory metal layer such as W, anisotropic processing is performed on a plurality of different material layers. The need brought new challenges to the dry etching process. That is, from the viewpoint of the vapor pressure of the halide, which is an etching reaction product, the Al-based metal layer is switched to the Cl-based gas and the W layer is switched to the F-based gas for patterning. The problem in the process to be performed will be described with reference to FIGS.

First, as shown in FIG. 3A, an adhesion layer 2 made of Ti or the like is formed on an insulating layer 1 on a semiconductor substrate (not shown).
A barrier metal layer 3 such as TiN, a refractory metal layer 4 such as W,
An Al-based metal layer 5 and an antireflection layer 6 are applied in this order to form a resist mask 7 for patterning. The antireflection layer 6 is for preventing irregular reflection of exposure light and performing exposure with good controllability when patterning a resist mask on the Al-based metal layer 5 having high reflectance. Al
It is necessary when there is a step on the surface of the base metal layer 5. Next, when the antireflection layer 6 and the Al-based metal layer 5 are etched with a Cl-based etching gas, as shown in FIG.
The 1Cl _x type reaction product adheres to the side surface of the resist mask 7, the patterned antireflection layer 6 and the Al type metal layer 5 as a side wall adhesion film 8 together with CCl _x which is a decomposition product of the resist. Next, the etching gas is switched to the F-based gas, and the refractory metal layer 4, the barrier metal layer 3 and the adhesion layer 2 are etched. At this time, the sidewall deposition film 8 AlCl _x system substitution of halogen atoms occurs by exposure to fluorine plasma, AlF as shown in FIG. 3 (c) _x
It is converted to the side wall altered film 10 of the system. The side wall altered film 9 is made of Al
Although it is a substance containing F ₃ as a main component, this AlF ₃ has a sublimation temperature of 1294 ° C. under atmospheric pressure, has a very low vapor pressure, and has low solubility in acids, alkalis, water, and organic solvents. It cannot be removed with a resist stripper. Also O ₂
When the resist ashing is performed with Al or O ₃ , the side wall altered film 9 is further converted into an Al ₂ O ₃ based substance, and the resist mask 7 is formed.
Since it covers the resist ashing,
Alternatively, after the resist ashing, it remains as a fence-like residue as shown in FIG. Especially in the latter case, the shape may be called a rabbit ear.

As described above, once the AlF _x -based sidewall altered film 10 is formed, it is difficult to remove it, and the step coverage of the interlayer insulating film or the like formed on the laminated wiring is deteriorated, causing a device failure. Becomes Further, the fence-like residue that has partly peeled off results in particle contamination in the substrate to be etched and the chamber of the etching apparatus. In addition, for strong removal, a wet process using strong mechanical and physical external forces such as spin cleaning and scrub cleaning is required, which may lead to device damage, process complexity, and throughput reduction. There is.

In order to avoid the formation of the AlF _x -based side wall altered film 10, the F-based gas is not used when the refractory metal layer 4 is etched, and a mixed gas of Cl-based gas and O-based gas is used to obtain a high melting point. Etching may be performed while forming a metal oxychloride. However, when this method is adopted for patterning of the laminated wiring, the side surface of the Al-based metal layer pattern is exposed to Cl-based plasma for a long time even after the patterning of the Al-based metal layer, so that excessive overetching is substantially continued. It becomes a state. Therefore, a new problem arises that side etching occurs in the anisotropically processed Al-based metal layer pattern.

Such side etching causes problems such as an increase in wiring resistance value, a decrease in operation speed, and a decrease in stress migration resistance in a semiconductor device having fine wiring of a sub-half micron class, which offsets the features of laminated wiring. It can happen.

Therefore, an object of the present invention is to achieve anisotropy without undercutting or side etching in patterning a laminated wiring of a fine width including a structure in which an Al-based metal layer is formed on a refractory metal layer. It is to newly provide an excellent patterning method.

Another object of the present invention is to provide A on the refractory metal layer.
In patterning a laminated wiring having a fine width including a structure in which an l-based metal layer is formed, fence-like residue is prevented from being generated, and anisotropic processing can be performed without fear of particle contamination of a substrate to be processed or a dry etching apparatus. It is to provide a clean patterning method.

A further object of the present invention is to form a reliable multilayer wiring structure which does not reduce the step coverage of the interlayer insulating film formed on the laminated wiring due to the altered film remaining on the side wall. It is to provide a method of patterning a laminated wiring which can be performed. Problems other than the above of the present invention,
This will be made clear by the description of the present specification and the accompanying drawings.

[0012]

A method of patterning a laminated wiring according to the present invention is proposed to solve the above-mentioned problems and includes a structure in which an Al-based metal layer is formed on a refractory metal layer. In the method of patterning the laminated wiring, A
The l-based metal layer is etched with a gas containing at least Br-based gas, and then the refractory metal layer is etched with a mixed gas containing at least Cl-based gas and O-based gas.

The method for patterning a laminated wiring according to the present invention is a method for patterning a laminated wiring that includes a structure in which an Al-based metal layer is formed on a refractory metal layer, wherein the Al-based metal layer contains at least a gas containing Br-based gas. Etching with
Subsequently, passivation treatment is applied to the side surface of the Al-based metal layer pattern,
After that, the refractory metal layer is etched by a mixed gas containing at least Cl-based gas and O-based gas.

The passivation treatment is an oxidation treatment, a nitriding treatment, a carbonization treatment or the like, and is a treatment for forming a thin layer such as AlO _x , AlN _x and AlC _{x having} a low chemical activity on the side surface of the Al-based metal layer pattern. Is. The formation means may be plasma treatment in a reactive atmosphere, heat treatment, chemical conversion treatment in a reaction solution, or the like.

The Br-based gas used in the present invention is HBr or B.
r ₂ , BBr ₃ , CBr ₄ , SiBr ₄ , S ₂ Br ₂ ,
Examples thereof include S ₃ Br ₂ and SBr ₂ . The O-based gas used in the present invention includes O ₂ , NO ₂ , and the like. Furthermore, the Cl-based gas used in the present invention includes HCl, Cl ₂ , B
Cl ₃ , CCl ₄ , SiCl ₄ , S ₂ Cl ₂ , S ₃ Cl
₂ and SCl ₂ can be exemplified.

In the present invention, it is desirable to control the substrate to be etched at room temperature or below, for example, 0 ° C. during etching. If the temperature of the substrate to be etched is excessively cooled, the etching rate will be lowered and the control of the etching apparatus will be complicated.

The present invention is particularly effective when patterning a sub-half micron class laminated wiring having a pattern width of 0.5 μm or less.

[0018]

The point of the present invention is that W, which is the lower layer of the laminated wiring, is used.
To provide a means for preventing side etching of the upper Al-based metal layer pattern, which has been patterned in advance, when etching a refractory metal layer such as the above with a mixed gas containing Cl-based gas and O-based gas. is there.

Specifically, the Al-based metal layer is etched by using an etching gas containing a Br-based gas, and AlBr _x or CBr _x , which is a reaction product of the layer to be etched or the resist and the etching gas, as a main component. Etching while forming a strong side wall protective film. This side wall protective film containing Br remains during the subsequent etching of the Al-based metal layer and protects the side wall of the Al-based metal layer pattern from the attack of Cl ^* (chlorine radical).

At this time, if the substrate to be etched is controlled at room temperature or lower during etching, the deposition of the side wall protective film containing AlBr _x or CBr _x as a main component is promoted, and
Since the reaction itself of Cl ^{* on} the side wall of the Al-based metal layer pattern is suppressed, the side etching prevention effect is thoroughly applied to the Al-based metal layer pattern.

On the other hand, the lower refractory metal layer such as W is Cl
Etching is performed with a mixed gas of a system gas and an O system gas.
As described above, WCl ₆ , which is a chloride of W, has a low vapor pressure, and its boiling point at 1 atm is as high as 346.7 ° C. Therefore, it is difficult to etch W only with Cl-based gas. However, the oxychloride WO _x Cl _y of W has a much higher vapor pressure, and the boiling point of WOCl ₄ which is a typical oxychloride is 227.5 ° C. The boiling point of WF ₆ is 17.5
Although it does not reach the temperature of 0 ° C., the refractory metal layer such as W can be sufficiently etched by a mixed gas of Cl-based gas and O-based gas. However, in comparison with the vapor pressure of WF ₆ , which is a reaction product when W is etched with an F-based gas, WOCl
It is also true that the vapor pressure of ₄ is quite small. Therefore, when the refractory metal layer such as W is etched with a mixed gas of Cl-based gas and O-based gas, the etching proceeds only in the ion irradiation surface in the form of an ion assist reaction.
That is, isotropic etching by Cl ^* does not occur, and the problem of side etching is solved. Also at this time,
It is effective to improve the anisotropy by controlling the substrate to be etched at room temperature or below. This is a significant difference from the case where the etching of W by the F-based gas facilitates the side etching due to the progress of the isotropic reaction due to F ^{* having} a poor directionality. The boiling point data is CRC Handbo
ok of Chemistry and Phisi
cs 71st. Edition (1990, CRC
Published by Press).

Further, since the F-based gas is not used after the etching of the upper Al-based metal layer, the AlCl _x- based sidewall adhesion film is not converted into the AlF _x- based sidewall altered film. For this reason, fence-like residues that are difficult to remove do not remain, and the problem of particle contamination in the substrate to be etched and the etching apparatus can be solved. At the same time, there is no reduction in the step coverage of the interlayer insulating film and the upper wiring formed later.

The present invention is based on the basic concept as described above, but in order to achieve further effects, a passivation treatment is applied to the side surface of the Al-based metal layer pattern on which patterning has been completed, and the Al-based metal is formed. It also provides a way to protect the layer pattern from Cl ^* attack. That is, AlO _x , AlN
The formation of the passive film such as _x and AlC _x eliminates the risk of side etching of the Al-based metal layer pattern.
The film thickness of these passivation films is several nm or less, and an increase in wiring resistance is not a problematic level. The presence of the nitride film or the carbide film also has a secondary effect of preventing the after-corrosion of the Al-based metal layer pattern.

Among the Br type gases and Cl type gases used in the present invention, sulfur bromide type gases such as S ₂ Br ₂ , S ₃ Br ₂ and SBr ₂ or S ₂ Cl ₂ , S ₃ Cl ₂ and SCl ₂ When an isochlorosulfur-based gas is used, free sulfur that is dissociated and generated in plasma is deposited on the substrate to be etched whose temperature is controlled below room temperature, and a side wall protective film of sulfur is formed on the pattern side wall parallel to the incident ions. Further, when N-based gas such as N ₂ is further added to these sulfur chloride-based gases, thiazyl (SN) is formed in the plasma, and this is polymerized immediately, so that the side wall protective film of polythiazyl (SN) _n can be used. Become. These sulfur side wall protective films are Cl
^* Protects the pattern side wall from the attack of ^* and contributes to further anisotropic processing. Further, since the sulfur-based side wall protective film can be easily sublimated and removed by heating the substrate to be etched under reduced pressure after the etching is completed, there is no fear of substrate contamination or reduction in particle level. The sublimation temperature is about 90 ° C. or higher for sulfur and about 150 ° C. or higher for polythiazyl.

In the present invention, Al is formed by the above mechanism.
Since it is possible to prevent side etching of the metal wiring, it is possible to solve various problems such as an increase in wiring resistance and after-corrosion when used for patterning a fine laminated wiring having a pattern width of 0.5 μm or less. It is possible and its effect is great.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the accompanying drawings.

Example 1 In this example, in patterning a laminated structure in which an Al-1% Si alloy layer was formed on a W layer, the Al-1% Si alloy layer was etched with an etching gas containing a Br-based gas. , W layer is an example of etching with a mixed gas containing Cl-based gas and O-based gas, which will be described with reference to FIGS. It should be noted that the same reference numerals are given to the same components as those in FIG. 3 used in the description of the conventional example.

First, as shown in FIG. 1A, an insulating film 1 such as SiO ₂ is formed on a semiconductor substrate (not shown) such as Si. Next, an adhesion layer 2 made of Ti, a barrier metal layer 3 made of TiN, a refractory metal layer 4 made of W by blanket CVD, an Al-based metal layer 5 made of Al-1% Si by sputtering, and an antireflection layer made of TiON. 6
Are formed in this order. After forming the barrier metal layer, RTA is performed at 650 ° C. for about 60 seconds in an inert atmosphere,
The barrier property may be improved. Although not shown, the insulating film 2 may have a multilayer wiring structure in which a connection hole is opened and which contacts an impurity diffusion region formed in the semiconductor substrate. Further, the semiconductor substrate such as Si is made of Al alloy or polycrystalline Si.
It may be a lower wiring layer composed of the like. The thickness of each layer is
As an example, the adhesion layer 2 is 30 nm and the barrier metal layer 3 is 7 nm.
0 nm, refractory metal layer 4 is 200 nm, Al-based metal layer 5
Is 300 nm and the antireflection layer 6 is 70 nm.

Next, as an example, a negative-type three-component chemically amplified photoresist SAL-601 manufactured by Shipley Co., Ltd.
And KrF excimer laser lithography gives 0.35
A resist mask mask 7 having a width of μm is formed. The sample shown in FIG. 1A formed so far is used as a substrate to be etched.

This substrate to be etched is first subjected to etching of the antireflection layer 6 made of TiON and the Al-based metal layer 5 under the following etching conditions by a substrate bias application type ECR plasma etching apparatus. Cl ₂ 60 sccm BCl ₃ 60 sccm HBr 30 sccm Gas pressure 2.0 Pa Microwave power 900 W (2.45 GHz) RF bias power 35 W (13.56 MH)
z) Substrate temperature 0 ° C. In this etching process, Cl ₂ and BC are generated by ECR discharge.
The radical reaction due to Cl ^* generated by dissociation from l ₃ is Cl
_The etching progresses anisotropically in the form of being assisted by ions such as _x ⁺ , BCl _x ⁺ and Br _x ⁺ , and the antireflection film 7 and the Al-based metal layer 5 generate TiCl _x , AlCl _x, etc. to be etched. Progressed. At the same time, on the side surfaces of the resist mask, the patterned antireflection layer 6 and the Al-based metal layer 5, as shown in FIG. 1B, CBr _x derived from the decomposition product of the resist mask and AlBr which is a reaction product. _X
Adhere to form a side wall protective film 8a and contribute to anisotropic processing. Since the substrate to be etched is controlled at 0 ° C and the radical reaction is suppressed, it has a good anisotropic shape.
An l-based metal layer 5 pattern was formed. When the surface of the refractory metal layer 4 is exposed, the etching stops at this surface.
This is because the vapor pressure of WCl ₆ and WBr ₆ is low and the etching rate is extremely small, as described above.

Next, switching to a Cl-based and O-based mixed gas,
As an example, the lower refractory metal layer 4, the barrier metal layer 3, and the adhesion layer 2 are patterned under the following etching conditions. Cl ₂ 90 sccm O ₂ 30 sccm HBr 10 sccm Gas pressure 2.0 Pa Microwave power 900 W (2.45 GHz) RF bias power 35 W (13.56 MH)
z) Substrate temperature 25 ° C. In this etching process, the refractory metal layer 4 such as W has Cl ^*.
The etching proceeds anisotropically in such a manner that the radical reaction due to is assisted by the incidence of ions such as Cl ⁺ and O ⁺ . This is because the reaction product to be desorbed is an oxychloride of W such as WOCl ₄ and has a relatively low vapor pressure, so that only the vertically incident surface of the ions incident on the substrate is etched. The barrier metal layer 3 and the adhesion layer 2 are removed by forming TiCl _x . At the same time, the side wall protective film 8b mainly composed of the decomposition products CCl _x and CBr _x of the resist mask 7 is deposited and contributes to the anisotropic processing of the refractory metal layer 4. Al
Since the side wall protective film 8a described above still remains on the side surface of the pattern of the base metal layer 5, the radical reaction due to Cl ^* is prevented. The state after etching is shown in FIG.

After that, the resist mask 7 and the side wall protective films 8a and 8b are removed by normal O ₂ plasma ashing, and the patterning of the Al / W based laminated wiring is completed as shown in FIG. 1D.

According to this embodiment, CBr _x and AlBr _x
By forming the side wall protective film 8a having high radical resistance due to the above, side etching of the Al-based metal layer 5 pattern is effectively prevented. Further, since the F-based gas is excluded from the etching gas for the refractory metal layer 4, the side wall protection film 8a is not converted into the AlF _x- based deteriorated film. Therefore, the sidewall protective film 8a can be easily removed by ashing after the etching is completed, and the fence-like residue is not left. When the resist mask 7 is removed by the resist stripping solution, the sidewall deposition films 8a and 8b can be removed by wet at the same time by the stripping solution treatment and the subsequent cleaning with pure water, and there is no fear of leaving any residue.

Example 2 In this example, in the etching of the laminated structure in which the Al-1% Si alloy layer was formed on the W layer, after etching the Al-1% Si alloy layer with an etching gas containing a Br-based gas. ,
This is an example in which the side surface of the Al-1% Si alloy layer pattern is plasma-nitrided for passivation, and then the W layer is etched with a mixed gas containing a Cl-based gas and an O-based gas, which is shown in FIG. This will be described with reference to (e). In FIG. 2, the same components as those in FIG. 3 used to describe the conventional example are designated by the same reference numerals.

Shown in FIG. 2A adopted in this embodiment.
The substrate to be etched is the substrate shown in FIG.
The same as the substrate to be etched shown in
Omitted. A substrate bias is applied to this substrate to be etched.
Type ECR plasma etching equipment
Anti-reflection consisting of TiON depending on the etching conditions
The layer 6 and the Al-based metal layer 5 are etched. Cl₂ 90 sccm BBr₃ 40 sccm Gas pressure 2.0 Pa Microwave power 900 W (2.45 GHz) RF bias power 35 W (13.56 MH)
z) Substrate temperature 0 ° C. In this etching process, Cl is generated by ECR discharge.₂From
Cl generated separately^*Radical reaction by Cl_x ⁺, BB
r_x ⁺And Br_x ⁺In the form of being assisted by ions such as
Etching progresses anisotropically, and the antireflection film 7 and Al-based metal
Layer 5 is TiCl _x, AlCl_xEtching to generate etc.
Has progressed. At the same time, the resist mask and pattern
The side surfaces of the antireflection layer 6 and the Al-based metal layer 5 which have been polished are shown in FIG.
Derived from decomposition products of resist mask as shown in (b)
CCl_x, CBr_xAnd reaction product AlBr_X
Adhere to form a side wall protective film 8a and contribute to anisotropic processing.
You. The substrate to be etched is controlled at 0 ° C and the radical reaction
A that has a good anisotropic shape because it is suppressed
An l-based metal layer pattern was formed. Etching has a high melting point
When the surface of the metal layer 4 is exposed, it stops at this surface.

Subsequently, A patterned under the following conditions
Plasma nitriding of the side surface of the 1-based metal layer 5 was performed. NH ₃ 90 sccm Ar 60 sccm Gas pressure 2.0 Pa Microwave power 900 W (2.45 GHz) RF bias power 0 W (13.56 MH)
z) Substrate temperature 0 ° C. In the plasma processing step, the sidewall protection film 8a is made of CN.
_{While x and the} like are removed, the passivation film 9 made of AlN is thinly formed on the side surface of the Al-based metal layer 5 pattern.

Next, switching to Cl-based and O-based mixed gas,
As an example, the lower refractory metal layer 4, the barrier metal layer 3, and the adhesion layer 2 are patterned under the following etching conditions. HCl 90 sccm O ₂ 20 sccm Gas pressure 2.0 Pa Microwave power 900 W (2.45 GHz) RF bias power 35 W (13.56 MH)
z) Substrate temperature 0 ° C. In this etching process, the refractory metal layer 4 such as W has Cl ^*.
The etching proceeds anisotropically in such a manner that the radical reaction due to is assisted by the incidence of ions such as Cl ⁺ and O ⁺ . This is because the reaction product to be desorbed is a WO _x Cl _y- based oxychloride such as WOCl ₄ and has a relatively low vapor pressure, so that only the vertical incident surface of the ions incident on the substrate is etched.
The barrier metal layer 3 and the adhesion layer 2 are removed by forming TiCl _x . At the same time, the side wall protective film 8b mainly composed of the decomposition product CCl _x of the resist mask 7 is deposited and contributes to the anisotropic processing of the refractory metal layer 4. The strong passivation film 9 described above is present on the side surface of the pattern of the Al-based metal layer 5 to prevent radical reaction due to Cl ^* . The state after etching is shown in FIG.

After that, the resist mask 7 and the side wall protective film 8b are removed by normal O ₂ plasma ashing, and
As shown in (e), the patterning of the Al / W-based laminated wiring is completed.

According to this embodiment, CBr _x and AlBr _x
By forming the side wall protective film 8a having high radical resistance by the above, side etching at the time of patterning the Al-based metal layer 5 is effectively prevented. Further, since the passivation film 9 made of AlN is formed after the patterning of the Al-based metal layer 5, the pattern of the Al-based metal layer 5 is not side-etched during the subsequent etching of the refractory metal layer 4. The side wall protective film 8b has a property that it can be easily removed by ashing after the end of etching, and does not leave a fence-like residue. When the resist mask 7 is removed by the resist stripping solution, the sidewall adhering film 8b can be removed by wet at the same time by the stripping solution treatment and the subsequent cleaning with pure water, and there is no risk of leaving any residue.

Although the present invention has been described with reference to the two examples, the present invention is not limited to these examples.

Blanket CVD as refractory metal layer 4
However, other refractory metals such as Ta and Mo, their alloys, and silicides may be used. Although Al-1% Si is illustrated as the Al-based metal layer 6, Al-Si-
Other Al alloys such as Cu alloys and Al-Cu alloys or pure Al may be used.

Although TiON is exemplified as the antireflection layer,
A-Si, Si by selecting conditions such as exposure wavelength
O ₂ , Si ₃ N ₄ , SiON, SiC, or an organic material may be appropriately selected and used. TiN was also used as the barrier metal layer, but TiON, TiW, TiSi _x
Etc. may be used. The barrier metal layer and the adhesion layer may not be used if there is no need.

Although plasma nitriding is used as an example of the passivation treatment, it may be plasma oxidation or plasma carbonization treatment in O ₂ gas or CH ₄ gas, for example. In addition to the plasma treatment, the passivation film may be formed by heat treatment in a reactive gas or chemical conversion treatment in a solution such as anodic oxidation.

The etching gas system is not limited to the examples given in the examples. For example, Br-based gas may be Br ₂ or CBr ₄ , Cl-based gas may be CCl ₄ , S or the like.
Other gases such as iCl ₄ may be used. When a sulfur bromide-based gas or a sulfur chloride-based gas is used, the deposition of a sulfur-based material can be used together as a sidewall protective film, which is more effective in preventing side etching due to the side wall protective effect. Also H
The addition of an I-based gas such as I is also effective in improving the selectivity with respect to the resist mask and the underlying material layer. Of course, an inert diluent gas such as Ar or He may be added. As the etching apparatus, a substrate bias application type ECR plasma etching apparatus was used.
The parallel plate type RIE apparatus, the magnetron RIE apparatus, the helicon wave plasma etching apparatus, etc. may be of any type.
Throughput can be improved by using a multi-chamber continuous processing system including a load lock chamber, an ashing chamber, and the like.

[0045]

As is apparent from the above description, according to the present invention, in a method of patterning a laminated wiring including a structure in which an Al-based metal layer is formed on a refractory metal layer such as W, the etching gas-based F method is used. After removing the system gas and etching the Al-based metal layer with the Br-based gas, the refractory metal layer is replaced with Cl-based and O-based.
The following effects are exhibited by etching with a mixed gas of the system.

When etching the Al-based metal layer, a Br-based gas is used.
By adopting CBr_xAnd AlBr _xStrong side wall protection
A protective film can be formed, and it can be used when patterning the Al-based metal layer.
Prevents de-etching and continues high melting point gold
Even when patterning the metal layer, the side surface of the Al-based metal layer pattern
Protect and prevent side etching.

Since the refractory metal layer is etched with a gas containing a mixed gas of Cl-based gas and O-based gas, the side wall protective film on the side surface of the Al-based metal layer pattern is made of Al.
There is no inconvenience of being converted into an F-based substance, and therefore there is no fear of deterioration of step coverage of the upper interlayer insulating film and particle contamination due to fence-like residues.

AlN is formed on the side wall of the Al-based metal layer pattern.
_If a thin and strong side wall protective film such as _x , AlO _x or AlC _x is formed, the side etching prevention effect is thoroughly achieved, and it is also an additional effect that it is effective in preventing after-corrosion.

Due to the above effects, low resistance, electromigration, stress migration, etc.
A method of patterning a laminated wiring having excellent resistance to various migrations and having low resistance and high reliability has been established, and its practical application becomes possible. The method of patterning a laminated wiring according to the present invention is particularly effective when used for an internal wiring of a semiconductor device having a fine wiring width of 0.5 μm or less, and the effect of the present invention is extremely large.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing Example 1 of a method for patterning a laminated wiring of the present invention in the order of steps, in which (a) is an adhesion layer, a barrier metal layer, a refractory metal layer on a base insulating film,
A state in which an Al-based metal layer, an antireflection layer and a resist mask are sequentially formed, (b) is a state in which the antireflection layer and the Al-based metal layer are patterned, and (c) is a refractory metal layer, an adhesion layer and a barrier metal. Patterned layer, (d)
Is a state in which the resist mask is removed by ashing to complete the laminated wiring.

FIG. 2 is a schematic cross-sectional view showing Example 2 of the method for patterning a laminated wiring according to the present invention in the order of steps, in which (a) is an adhesion layer, a barrier metal layer, a refractory metal layer, and
A state in which an Al-based metal layer, an antireflection layer and a resist mask are sequentially formed, (b) is a state in which the antireflection layer and the Al-based metal layer are patterned, and (c) is a passivation treatment on the side surface of the Al-based metal layer pattern. 6D, the high melting point metal layer, the adhesion layer and the barrier metal layer are subsequently patterned, and FIG. 6E is the state where the laminated wiring is completed by removing the resist mask by ashing.

FIG. 3 is a schematic cross-sectional view showing a problem in a conventional method for patterning a laminated wiring, wherein (a) is an adhesion layer, a barrier metal layer, a refractory metal layer, an Al-based metal layer, an antireflection film on a base insulating film. Layer and a resist mask are sequentially formed, (b) is a state in which a side wall protective film is formed by patterning an antireflection layer and an Al-based metal layer, and (c) is a state in which a refractory metal layer, an adhesion layer, and a barrier are continuously formed. The metal layer is patterned to form a side wall altered film, and (d) is a state in which the resist mask is removed by ashing to form a fence-like residue.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating film 2 Adhesion layer 3 Barrier metal layer 4 Refractory metal layer 5 Al-based metal layer 6 Antireflection layer 7 Resist mask 8, 8a, 8b Side wall protective film 9 Passive film 10 Side wall altered film

Claims (5)

[Claims] 1. A method for patterning a laminated wiring including a structure in which an Al-based metal layer is formed on a refractory metal layer, wherein the Al-based metal layer is etched with a gas containing at least Br-based gas, and then the high-melting metal layer is etched. The melting point metal layer is at least C
A method of patterning a laminated wiring, which comprises etching with a mixed gas containing an l-based gas and an O-based gas. 2. A method for patterning a laminated wiring including a structure in which an Al-based metal layer is formed on a refractory metal layer, wherein the Al-based metal layer is etched with a gas containing at least Br-based gas, and then the Al-based metal layer is continuously etched. A method for patterning a laminated wiring, which comprises subjecting a side surface of a system metal layer pattern to a passivation treatment, and thereafter etching the refractory metal layer with a mixed gas containing at least a Cl system gas and an O system gas. 3. The passivation treatment is any one of oxidation treatment, nitriding treatment and carbonization treatment,
The method for patterning a laminated wiring according to claim 2. 4. The method for patterning a laminated wiring according to claim 1, wherein the substrate to be etched is controlled to a room temperature or lower during etching. 5. The method for patterning a laminated wiring according to claim 1, wherein the pattern width of the laminated wiring is 0.5 μm or less.