JP3353490B2 - Patterning method for laminated wiring - Google Patents

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 particularly, to a method of patterning a laminated wiring including a structure in which an Al-based metal layer is formed on a refractory metal layer. About the method.

[0002]

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

[0003] As one of measures against such various migrations, as in Al-Cu and Al-Si-Cu,
Methods such as alloying with a low-resistance metal such as Cu and lamination with a barrier metal such as TiN have been adopted. In recent years, as a more effective wiring structure, a high-melting-point metal such as W, Mo or Ta, an alloy thereof, a compound, etc., which can secure a certain degree of conductivity and a high-rigidity wiring layer is formed below the Al-based metal layer. The formed laminated wiring is being studied. High melting point metals such as W have remarkably higher electromigration resistance than Al-based metals. For example, the 35th Federation of Applied Physics-related lectures (Spring 1988) p642, lecture number 29p-V-9 And is widely known. However, since W has a higher electric resistance than Al, a single layer shows an increase in wiring resistance and a decrease in signal propagation speed. Therefore, a combination of both is used even if a low-resistance Al-based metal layer is disconnected. Due to the presence of the high melting point metal layer,
It is based on the idea that disconnection can be avoided in the entire wiring layer by utilizing the redundancy effect. Among them, when W is used, it is a material having a relatively low resistance among the high melting point metals, and a film formation method by blanket CVD has been established, so that it is expected as a highly reliable laminated wiring structure in the future. .

[0004]

However, in the patterning of a laminated wiring including a structure in which an Al-based metal layer is formed on a high melting point metal layer such as W, anisotropic processing is performed on a plurality of different material layers. The need has brought new difficulties to the dry etching process. That is, from the viewpoint of the vapor pressure of the halide as 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 high melting point metal layer 4 such as W,
An Al-based metal layer 5 and an antireflection layer 6 are applied in this order, and a resist mask 7 for patterning is formed. The anti-reflection layer 6 is used for patterning a resist mask on the Al-based metal layer 5 having high reflectivity to prevent irregular reflection of exposure light and perform exposure with good controllability. Al
This is necessary when the surface of the system metal layer 5 has a step. Next, when the anti-reflection layer 6 and the Al-based metal layer 5 are etched with a Cl-based etching gas, as shown in FIG.
The lCl _x -based reaction product, together with CCl _x , which is a decomposition product of the resist, adheres to the resist mask 7, the patterned antireflection layer 6, and the side surface of the Al-based metal layer 5 as a sidewall adhesion film 8. Next, the etching gas is switched to an 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 into a side wall altered film 10 of the system. The side wall altered film 9 is made of Al
This substance is a substance containing F ₃ as a main component, and since this AlF ₃ has a sublimation temperature under atmospheric pressure of 1294 ° C. and a very low vapor pressure, and has a low solubility in acids, alkalis, water and organic solvents, It cannot be removed with a resist stripper. Also O ₂
When resist ashing is performed with O ₃ or O ₃ , the side wall altered film 9 is further converted to an Al ₂ O ₃ -based material,
So that it may interfere with resist ashing,
Alternatively, even after the resist ashing, it remains as a fence-shaped residue as shown in FIG. Particularly in the latter case, it may be called a rabbit ear because of its shape.

[0006] As described above, once the AlF _x -based deteriorated film 10 is formed, it is difficult to remove it, and the step coverage of an interlayer insulating film or the like formed on the laminated wiring is degraded, causing a device failure. Becomes In addition, the fence-shaped residue that has been partially peeled off results in particle contamination in the substrate to be etched and the chamber of the etching apparatus. In order to remove by force, a wet process using a strong mechanical / physical external force such as spin cleaning or scrub cleaning is required, which may cause damage to the device, complicate the process, and decrease the throughput. 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 at the time of etching the refractory metal layer 4, and a mixed gas of a Cl-based gas and an O-based gas is used. The etching may be performed while forming a metal oxychloride. However, if this method is adopted for patterning the laminated wiring, the side surface of the Al-based metal layer pattern is exposed to the Cl-based plasma for a long time even after the patterning of the Al-based metal layer is completed, so that substantially excessive over-etching is continued. State. For this reason, there is a new problem that side etching occurs in the Al-based metal layer pattern that has been anisotropically processed.

Such side etching causes problems such as an increase in wiring resistance, a decrease in operation speed, and a decrease in stress migration resistance in a semiconductor device using sub-half micron-class fine wiring, and offsets the features of the stacked wiring. Maybe.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an anisotropic pattern having no undercut or side etching in patterning of a fine-width laminated wiring including a structure in which an Al-based metal layer is formed on a high-melting metal layer. It is to provide a new excellent patterning method.

Another object of the present invention is to provide a method for forming an A
In patterning a fine-width stacked wiring including a structure in which an l-based metal layer is formed, it is possible to prevent the generation of fence-like residues and perform anisotropic processing without fear of particle contamination of a substrate to be processed or a dry etching apparatus. It is to provide a clean patterning method.

Another object of the present invention is to form a reliable multilayer wiring structure which does not lower the step coverage of an interlayer insulating film formed on a laminated wiring due to a deteriorated film remaining on a side wall. It is an object of the present invention to provide a method for patterning a laminated wiring that can be performed. Problems other than the above of the present invention are:
It is made clear by the description in the present specification and the accompanying drawings.

[0012]

SUMMARY OF THE INVENTION A method for 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 high melting point metal layer. In the method for patterning a laminated wiring, A
The l-type metal layer is etched with a gas containing at least a Br-based gas, and thereafter, the refractory metal layer is etched with a mixed gas containing at least a Cl-based gas and an O-based gas.

The method of patterning a laminated wiring according to the present invention is a method of patterning a laminated wiring including a structure in which an Al-based metal layer is formed on a high-melting metal layer, wherein the Al-based metal layer is formed of a gas containing at least a Br-based gas. Etching with
Subsequently, passivation treatment is performed on the side surface of the Al-based metal layer pattern,
Thereafter, the high melting point metal layer is etched by a mixed gas containing at least a Cl-based gas and an O-based gas.

The passivation treatment is an oxidation treatment, a nitridation treatment, a carbonization treatment, or the like, and a treatment for forming a thin layer of AlO _x , AlN _x, AlC _x or the like having a low chemical activity on the side surface of the Al-based metal layer pattern. It is. The forming means is not limited, such as a plasma treatment in a reactive atmosphere, a heat treatment, and a chemical conversion treatment in a reaction solution.

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

In the present invention, it is desirable that the substrate to be etched be controlled to a room temperature or less, for example, 0 ° C. during etching. If the temperature of the substrate to be etched is excessively cooled, the etching rate is lowered, and the management of the etching apparatus is 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.
In etching a high melting point metal layer such as a mixture gas containing a Cl-based gas and an O-based gas, a means for preventing side etching of an upper Al-based metal layer pattern that has been previously patterned is provided. is there.

More specifically, the etching of the Al-based metal layer employs an etching gas containing a Br-based gas, and mainly includes AlBr _x or CBr _x which is a reaction product between the layer to be etched or the resist and the etching gas. Etching while forming a strong side wall protective film. This sidewall protective film containing Br remains during the etching of the Al-based metal layer while continuously applying a substrate bias, and protects the sidewall of the Al-based metal layer pattern from Cl ^* (chlorine radical) attack.

At this time, if the substrate to be etched is controlled at room temperature or lower during the etching, the deposition of the sidewall protective film mainly composed of AlBr _x or CBr _x is promoted, and
Since the reaction of Cl ^{* on} the side wall portion of the Al-based metal layer pattern itself is suppressed, the effect of preventing side etching in the Al-based metal layer pattern is thorough.

On the other hand, the lower refractory metal layer such as W
Etching is performed using 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 a high boiling point at 1 atm of 346.7 ° C., so that it is difficult to etch W with only a Cl-based gas. However, the vapor pressure of W oxychloride WO _x C _y is much higher, and the boiling point of WOCl ₄ , which is a typical oxy chloride, is 227.5 ° C. 17.5 which is the boiling point of WF ₆
Although not as high as ° C., the refractory metal layer such as W can be sufficiently etched by a mixed gas of a Cl-based gas and an O-based gas. However, when compared 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. For this reason, when a high melting point metal layer such as W is etched by a mixed gas of a Cl-based gas and an O-based gas, the etching proceeds only on the ion irradiation surface in the form of an ion-assisted reaction.
That is, isotropic etching by Cl ^* does not occur, and the problem of side etching is solved. At this time,
Controlling the substrate to be etched to a temperature equal to or lower than room temperature is effective for improving anisotropy. This is significantly different from the fact that in the case of etching W with an F-based gas, an isotropic reaction due to poor directivity of F ^* proceeds and side etching easily occurs. The data of the boiling point is CRC Handbo
ok of Chemistry and Physi
cs 71st. Edition (1990, CRC
Press).

Further, since the F-based gas is not used after the etching of the upper Al-based metal layer, the AlCl _x -based side wall adhered film is not converted into an AlF _x -based side wall altered film. For this reason, a fence-shaped residue that is difficult to remove does 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, the step coverage of the interlayer insulating film and the upper wiring to be formed later is not reduced.

Although the present invention is based on the basic concept as described above, in order to further enhance the effect, a passivation treatment is performed on the side surface of the patterned Al-based metal layer pattern, and the Al-based metal It also provides a way to protect the layer pattern from Cl ^* attacks. That is, AlO _x , AlN
By forming a passivation film such as _x and AlC _{x, there} is no fear of side etching of the Al-based metal layer pattern.
The film thickness of these passivation films is several nm or less, and the increase in wiring resistance is not at a level that causes a substantial problem. The presence of the nitride film or the carbide film also has a secondary effect of preventing after-corrosion of the Al-based metal layer pattern.

Among the Br-based gases and Cl-based gases used in the present invention, sulfur bromide-based 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 isochloride-based gas is used, free sulfur dissociated and generated in the plasma is deposited on the substrate to be etched at a temperature lower than room temperature, and forms a sulfur sidewall protective film on the pattern sidewall parallel to the incident ions. If an 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. Therefore, it is possible to use a sidewall protective film of polythiazyl (SN) _n. Become. These sulfur-based side wall protective films are made of Cl.
^* Protects the pattern side wall from attack and contributes to further anisotropic processing. In addition, since these sulfur-based side wall protective films can be easily removed by sublimation by heating the substrate to be etched under reduced pressure after etching, there is no fear of substrate contamination or reduction in particle level. The sublimation temperature is about 90 ° C. or more for sulfur and about 150 ° C. or more for polythiazyl.

In the present invention, Al
Since it becomes possible to prevent side etching of the system metal wiring, it is possible to solve various problems such as an increase in wiring resistance and after-corrosion particularly when used for patterning a fine laminated wiring having a pattern width of 0.5 μm or less. The effect can be great.

[0026]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

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

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 properties may be improved. Although not shown, the insulating film 2 may have a multi-layer wiring structure in which a connection hole is opened to make contact with an impurity diffusion region formed in the semiconductor substrate. Semiconductor substrates such as Si are made of Al alloy or polycrystalline Si.
A lower wiring layer made of the same may be used. 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 thickness of 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.
0.35 by KrF excimer laser lithography
A resist mask having a width of μm is formed. The sample formed so far and shown in FIG. 1A is used as a substrate to be etched.

The anti-reflection layer 6 made of TiON and the Al-based metal layer 5 are first etched from the substrate to be etched by a substrate bias applying type ECR plasma etching apparatus under the following etching conditions, for example. 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 step, Cl ₂ and BC are
Cl ^* by radical reaction Cl to dissociated from l _3
The etching proceeds anisotropically in a form 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. Advanced. At the same time, on the side surfaces of the resist mask and 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 are formed. _X
Adheres to form the 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, A having a good anisotropic shape
5 patterns of the l-based metal layer were 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 or WBr ₆ is low and the etching rate is extremely low as described above.

Next, the mixture is switched to a Cl-based and O-based mixed gas.
As an example, the lower refractory metal layer 4, barrier metal layer 3, and 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)
The z) substrate temperature 25 ° C. This etching step, the refractory metal layer 4 such as W is Cl ^*
Etching proceeds anisotropically in such a manner that a radical reaction caused by Cl ⁺ and O ⁺ is assisted by the incidence of ions such as Cl ⁺ and O ⁺ . This is because the desorbed reaction product is W oxychloride such as WOCl ₄ and the vapor pressure is relatively low, so that only the vertical incidence surface of 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, a side wall protective film 8b mainly composed of decomposition products CCl _x and CBr _x of the resist mask 7 is attached and contributes to the anisotropic processing of the high melting point metal layer 4. Al
Since the above-mentioned side wall protective film 8a remains on the side surface of the pattern of the base metal layer 5, the radical reaction due to Cl ^* is prevented. FIG. 1C shows the state after the end of the etching.

Thereafter, the resist mask 7 and the side wall protective films 8a and 8b are removed by ordinary O2 plasma ashing, and a substrate bias is applied as shown in FIG.
Then, the patterning of the Al / W-based stacked wiring by the etching performed is completed.

According to the present embodiment, CBr _x or AlBr _x
By forming the sidewall protective film 8a having high radical resistance due to the above, side etching of the pattern of the Al-based metal layer 5 is effectively prevented. Further, by the etching gas of the refractory metal layer 4 to eliminate the F-based gas, never the sidewall protection film 8a is converted into altered membrane AlF _x system. For this reason, the sidewall protective film 8a can be easily removed by ashing after the end of the etching, and a fence-shaped residue does not remain. When the resist mask 7 is removed with a resist stripping solution, the side wall deposition films 8a and 8b can be simultaneously wet-removed by the stripping solution treatment and the subsequent pure water cleaning, and there is no possibility of leaving any residue.

Embodiment 2 In this embodiment, in the etching of a laminated structure in which an Al-1% Si alloy layer is formed on a W layer, the Al-1% Si alloy layer is etched 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 and subjected to a passivation treatment, and then the W layer is etched with a mixed gas containing a Cl-based gas and an O-based gas, as shown in FIG. This will be described with reference to FIGS. In FIG. 2, the same components as those in FIG. 3 used for the description of the conventional example are given the same reference numerals.

FIG. 2A employed in this embodiment is shown in FIG.
The substrate to be etched is the same as that shown in FIG.
It is the same as the substrate to be etched shown in
Omitted. The substrate to be etched is applied with a substrate bias.
Type ECR plasma etching equipment
First anti-reflection made of TiON depending on the etching conditions
The layer 6 and the Al-based metal layer 5 are etched. Cl_Two 90 sccm BBr_Three 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 step, Cl is discharged by ECR discharge._TwoSolution from
Cl generated by separation^*Radical reaction caused by Cl_x ⁺, BB
r_x ⁺And Br_x ⁺In the form assisted by ions such as
The etching proceeds anisotropically, and the antireflection film 7 and the Al-based metal
Layer 5 is TiCl _x, AlCl_xEtching to generate etc.
Has progressed. At the same time, resist mask and patterning
FIG. 1 shows a side view of the anti-reflection layer 6 and the Al-based metal layer
Derived from decomposition products of resist mask as shown in (b)
CCl_x, CBr_xAnd the reaction product AlBr_X
Adheres to form the sidewall protective film 8a and contribute to anisotropic processing.
You. The substrate to be etched is controlled at 0 ° C.
A with good anisotropic shape
An l-based metal layer pattern was formed. Etching is 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 l-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 this plasma processing step, the side wall protective film 8a is formed of CN
While removed becomes _x, etc., passive film 9 made of thin AlN in the Al-based metal layer 5 pattern side is formed.

Next, switching to a Cl-based and O-based mixed gas,
As an example, the lower refractory metal layer 4, barrier metal layer 3, and 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)
The z) substrate temperature 0 ℃ the etching step, the refractory metal layer 4 such as W is Cl ^*
Etching proceeds anisotropically in such a manner that a radical reaction caused by Cl ⁺ and O ⁺ is assisted by the incidence of ions such as Cl ⁺ and O ⁺ . The reaction product which leaves are WO _x Cl _y based oxychlorides of such WOCl _4, because due to the relatively low vapor pressure only the vertical plane of incidence of 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 attached 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, and prevents a radical reaction due to Cl ^* . FIG. 2D shows the state after the completion of the etching.

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

According to the present embodiment, CBr _x or AlBr _x
By forming the sidewall protection film 8a having high radical resistance due to the above, the side etching at the time of patterning the Al-based metal layer 5 is effectively prevented. In addition, since the passivation film 9 made of AlN is formed after the patterning of the Al-based metal layer 5 is completed, the pattern of the Al-based metal layer 5 is not subjected to side etching even when the refractory metal layer 4 is subsequently etched. The sidewall protective film 8b has such a property that it can be easily removed by ashing after the etching, and does not leave a fence-like residue. When the resist mask 7 is removed with a resist stripper, the side wall adhesion film 8b can be simultaneously wet-removed by the stripper solution treatment and the subsequent pure water cleaning, and there is no risk of leaving any residue.

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

Blanket CVD as high melting point metal layer 4
However, other refractory metals such as Ta and Mo, alloys thereof, and silicide may be used. Although Al-1% Si is exemplified as the Al-based metal layer 6, Al-Si-
Other Al alloys such as Cu alloy and Al-Cu alloy or pure Al may be used.

Although TiON is exemplified as the antireflection layer,
By selecting conditions such as exposure wavelength, a-Si, Si
O ₂ , Si ₃ N ₄ , SiON, SiC or an organic material may be appropriately selected and used. Barrier was also used TiN as a metal layer, TiON, TiW, TiSi _x
Etc. may be used. The barrier metal layer and the adhesion layer may not be used if unnecessary.

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

The etching gas system is not limited to the examples described in the embodiments. For example, Br ₂ or CBr ₄ as a Br-based gas, CCl ₄ or S as a Cl-based gas
Other gases such as iCl ₄ may be used. If a sulfur bromide-based gas or a sulfur chloride-based gas is used, the deposition of a sulfur-based material can be used in combination as a sidewall protective film, which is effective in preventing side etching by a further sidewall protective effect. Also H
Addition of an I-based gas such as I is also effective for improving the selectivity with respect to a resist mask and a base material layer. Of course, an inert diluent gas such as Ar or He may be added. The etching device used was a substrate bias application type ECR plasma etching device.
A parallel plate type RIE apparatus, a magnetron RIE apparatus, a helicon wave plasma etching apparatus and the like are not particularly limited.
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 the method of patterning a laminated wiring including a structure in which an Al-based metal layer is formed on a high-melting-point metal layer such as W, an etching gas system is used to convert F to F. After removing the Al-based gas and etching the Al-based metal layer with the Br-based gas, the refractory metal layer is changed to Cl-based and O-based.
The following effects are exhibited by etching with a system mixed gas.

Br-based gas when etching the Al-based metal layer
The adoption of CBr_xAnd AlBr _xStrong sidewall protection
A protective film can be formed, and the
High-melting point gold
When patterning the metal layer, keep the Al-based metal layer pattern side
Protect to prevent side etching.

Since the refractory metal layer is etched with a gas containing a mixed gas of a Cl-based gas and an 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 F-based material, and therefore, there is no fear of deterioration of step coverage of the upper interlayer insulating film due to the fence-like residue or particle contamination.

On the side walls of the Al-based metal layer pattern, AlN
_If a thin and strong sidewall protective film such as _x , AlO _x, or AlC _x is formed, the side etching preventing effect is thorough, and it is an incidental effect that it is effective in preventing after-corrosion.

By the above effects, low resistance and electromigration, stress migration, etc.
A method for patterning a multilayer wiring with excellent resistance to various migrations and a low resistance and high reliability has been established, and its practical use is possible. The method of patterning a laminated wiring according to the present invention is particularly effective when used for 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 the drawings]

FIG. 1 is a schematic cross-sectional view showing a first embodiment of a method for patterning a laminated wiring according to the present invention in the order of steps, and FIG. 1 (a) shows an adhesion layer, a barrier metal layer, a high melting point metal layer on a base insulating film;
An Al-based metal layer, an anti-reflection layer and a resist mask are sequentially formed, (b) is a state in which the anti-reflection layer and the Al-based metal layer are patterned, and (c) is a refractory metal layer, an adhesion layer and a barrier metal. State where the layer is patterned, (d)
Shows a state where the laminated wiring is completed by removing the resist mask by ashing.

FIG. 2 is a schematic sectional view showing Example 2 of the method of patterning a laminated wiring according to the present invention in the order of steps, and FIG. 2 (a) shows an adhesion layer, a barrier metal layer, a high melting point metal layer on a base insulating film;
A state in which an Al-based metal layer, an anti-reflection layer and a resist mask are sequentially formed, (b) shows a state in which the anti-reflection layer and the Al-based metal layer are patterned, and (c) shows a passivation treatment on the side surface of the Al-based metal layer pattern. (D) is a state in which the refractory metal layer, the adhesion layer and the barrier metal layer are continuously patterned, and (e) is a state in which the resist mask is removed by ashing to complete the laminated wiring.

FIG. 3 is a schematic cross-sectional view showing a problem in a conventional method of patterning a laminated wiring, in which (a) shows an adhesion layer, a barrier metal layer, a refractory metal layer, an Al-based metal layer, an anti-reflection layer on a base insulating film. (B) is a state in which an antireflection layer and an Al-based metal layer are patterned to form a side wall protective film, (c) is a state in which a refractory metal layer and an adhesion layer, and a barrier are continuously formed. The state in which the side wall altered film is formed by patterning the metal layer, and the state (d) is a state in which the resist mask is removed by ashing to form a fence-shaped 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 Anti-reflection layer 7 Resist mask 8, 8a, 8b Side wall protective film 9 Passive film 10 Side wall altered film

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/3065 H01L 21/3213 C23F 1/00-4/04

Claims (6)

(57) [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 a Br-based gas, and The melting point metal layer should be at least C
A patterning method for a laminated wiring, characterized by etching with a mixed gas containing an l-based gas and an O-based gas. 2. A method of 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 a Br-based gas. A patterning method for a laminated wiring, wherein a passivation treatment is performed on a side surface of a system metal layer pattern, and thereafter, the refractory metal layer is etched with a mixed gas containing at least a Cl system gas and an O system gas. 3. The passivation treatment is any one of an oxidation treatment, a nitridation treatment and a carbonization treatment,
The method for patterning a laminated wiring according to claim 2. 4. The method according to claim 1, wherein the substrate to be etched is controlled at room temperature or lower during etching. 5. The method according to claim 1, wherein a pattern width of the stacked wiring is 0.5 μm or less. 6. The refractory metal layer is formed of the Al-based metal layer.
Electromigration and stress migration
Claims, characterized in that it is a redundant layer for countermeasures.
3. The method for patterning a laminated wiring according to claim 1.