JPH07122541A - Machining method for aluminium based wiring - Google Patents

Abstract

PURPOSE:To provide a method for machining an aluminium based wiring in which resist mask and side wail protective film can be removed efficiently in a short time while suppressing generation of dust. CONSTITUTION:After an aluminium based material layer 3 is subjected to dry etching using a resist mask 4, a side wall protective film 5 deposited on the pattern side wall is subjected to etching using SF6/Cl2 mixture gas. Subsequently, the resist mask 4 is removed by ashing. The residue is then removed thoroughly by RA stripper process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing aluminum (Al) -based wiring applied to the manufacture of semiconductor devices, for example, and more particularly to a method for reducing the time required for ashing and reducing dust.

[0002]

2. Description of the Related Art Generally, in the field of semiconductor device manufacturing, Al-based wiring is processed by using an aluminum-based material layer (Al-
A resist mask provided on Si, Al-Si-Cu) is patterned by photolithography, then dry etching is performed using this as a mask, and the resist mask is removed.

For example, as shown in FIG. 5, for a wafer 1 in which an aluminum-based material layer 3 is formed on an interlayer insulating film 2 and a patterned resist mask 4 is further formed thereon. Consider the case of wiring processing.

First, the aluminum-based material layer 3 masked by the resist mask 4 is dry-etched. For this etching, chlorine (C
L ₂ ) or Cl is used as a discharge gas to dissociate gas, and reactive ion etching (RI) is used.
E) is performed.

When this RIE is performed, as shown in FIG. 6, a region not masked by the resist mask 4 while the side wall protective film 5 obtained by forward sputtering of the resist mask 4 is formed. The aluminum-based material layer 3 is removed. The side wall protective film 5 is mainly composed of a carbon-based reaction product such as CCl _x polymer derived from the decomposition product of the resist mask 4, but is sputtered out from the aluminum-based material layer 3 or the interlayer insulating film 2. It also incorporates Al and Si.

As described above, the aluminum-based material layer 3
After etching, the resist mask 4 is removed.
The removal of the resist mask 4 is typically performed by plasma ashing using oxygen plasma discharge, which has a very high performance of removing the resist mask 4 made of an organic material.

Then, this oxygen plasma ashing is performed.
Then, as shown in FIG. 7, the resist mask 4
Are removed. However, the portion corresponding to the side wall protective film 5
Is not sufficiently removed and remains as a residue 6.
This is mainly due to Al taken in the side wall protection film 5.
And Si are converted to AlO by oxygen plasma during ashing.
_xAnd SiO_xIt changes into oxide and remains without being vaporized
This is because it will end up.

Then, for example, a concentrated nitric acid-based stripping agent (manufactured by Kanto Chemical Co .; trade name RA stripper) is used to remove the residue 6
Are being removed.

[0009]

By the way, the above-mentioned residue 6
If the wafer 1 is sent to the next step with insufficient removal of the above, the residue 6 scatters and causes dust, and problems such as deterioration of coverage due to the interlayer insulating film occur.

For this reason, the treatment with the above-mentioned release agent is required, but in reality, it is possible to completely remove the residue 6 by one treatment.
Is difficult to remove, and is usually removed by repeating the above-mentioned stripping agent treatment and ashing treatment many times. However, this requires a great deal of work time.

If the residue 6 is removed for a long time and the residue 6 is adhered to the aluminum-based material layer 3 for a long time, the after-corrosion resistance of the aluminum-based material layer 3 may be deteriorated. is there. Side wall protection film 5
Is composed of CCl _x polymer, which is a carbon-based reaction product, and incorporates Al and Si.
In addition to 1 and Si, low molecular chlorine compounds and chlorine gases are also stored. Even if the sidewall protection film 5 becomes a residue 6 by ashing, the CCl _x remaining after ashing is left.
Since the polymer is decomposed to generate a chlorine-based gas or the stored chlorine-based gas is gradually released, if the residue 6 is attached to the aluminum-based material layer 3 for a long time, Al It can also cause corrosion.

Further, from the viewpoint of avoiding plasma irradiation damage, it is not preferable to repeat the ashing many times. Therefore, it is desired to sufficiently remove the resist mask 4 and the sidewall protection film 5 in a short time in processing the aluminum wiring.

Therefore, the present invention has been proposed in view of the above-mentioned conventional circumstances, and processing of an aluminum-based wiring capable of efficiently removing a resist mask and a side wall protective film in a short time and suppressing generation of dust. The purpose is to provide a method.

[0014]

As a result of intensive studies by the inventors of the present invention, the residue left after the ashing of the resist mask is mainly Al taken in the side wall protective film. Since it was an oxide derived from Si or Si, it was found that removal of the side wall protective film prior to this ashing prevents the formation of the oxide as described above and can efficiently perform the ashing in the next step. The present invention has been completed.

That is, in the method for processing an aluminum-based wiring according to the present invention, a step of dry etching an aluminum-based material layer through a resist mask and a sidewall protection film deposited on the pattern sidewall surface in the etching are
A step of removing using an etching gas containing at least a fluorine compound and a chlorine compound;
And a step of removing the mask.

The etching of the side wall protective film is performed in order to prevent oxidation of Al and Si taken in by the etching.
It is preferable to perform the preceding step, that is, the step of etching the aluminum-based material layer and the continuous step. At this time, the etching of the side wall protective film may be performed in the same chamber as that used in the previous step, or may be performed using a multi-chamber type device.

The fluorine-based compound forming the etching gas is effective in removing Si contained in the sidewall protection film, and the chlorine-based compound is also effective in removing Al contained in the sidewall protection film. is there. Therefore, when the side wall protective film is removed using such an etching gas, not only the CCl _x polymer and the like which form the side wall protective film are decomposed and removed, but also the components such as Al and Si are removed.

The etching gas is not particularly limited as long as it contains at least a fluorine-based compound and a chlorine-based compound, and examples thereof include SF ₆ / Cl ₂ mixed gas. As the fluorine-based compound, the above SF
Other than ₆ , for example, C ₂ F ₆ , CF ₄ or the like can be used.

The resist mask may be removed by ashing after removing the side wall protective film described above. Further, after the ashing, if a stripping agent treatment is further performed, the residue derived from the resist mask and the sidewall protection film that is not removed after the ashing is thoroughly removed. The method of this ashing or stripping agent treatment is not particularly limited, and any conventionally known method can be applied, but the processing conditions etc. are appropriately optimized depending on the type of resist / mask, film thickness, etc. Just go.

[0020]

The reason why the sidewall protection film can be removed and the resist mask can be effectively removed by the method for processing an aluminum-based wiring according to the present invention is considered to be as follows.

When etching the aluminum-based material layer,
The side wall protective film deposited on the turn side wall surface is mainly formed by resist.
.CCl derived from decomposition products of mask_xPolymer, etc.
It consists of carbon-based reaction products,
Also removes Al and Si sputtered out from the interlayer insulating film
It is crowded. Therefore, in this state the resist mass
When ashing is performed to remove the ash,
These ingredients are AlO _xAnd SiO_xSuch as an oxide
Will remain.

Therefore, before the ashing, etching / etching containing at least a fluorine compound and a chlorine compound is performed.
When the side wall protective film is etched using gas, the fluorine radicals F ^* generated from the fluorine-based compound bond with Si in the side wall protective film and remove this Si. Similarly,
Cl ^* generated from the chlorine-based compound is A in the side wall protective film.
Combined with l, this Al is removed. Therefore, when the side wall protective film is removed using such an etching gas, the CCl _x polymer or the like forming the side wall protective film is decomposed, and the components such as Al and Si do not remain.

In this way, the sidewall protection film, which has been a problem when removing the resist mask conventionally, is removed, so that ashing can be performed efficiently in a short time.
Further, the removal of dust is suppressed by sufficiently removing the side wall protective film.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the aluminum-based wiring processing method according to the present invention is applied will be described below with reference to the drawings.

In the present embodiment, wiring processing was performed on a wafer 1 having a diameter of 6 inches as shown in FIG.
The wafer 1 has an aluminum-based material layer 3 on the interlayer insulating film 2.
Is formed, and a patterned resist mask 4 is further formed thereon. The aluminum-based material layer 3 is made of Al-1% Si,
Is made of SiO ₂ .

First, the aluminum-based material layer 3 whose predetermined area was masked by the resist mask 4 was etched by a magnetic field microwave plasma etching apparatus. The etching conditions are as shown below.

Etching conditions Etching gas: Cl ₂ gas 90 sccm BCl ₃ gas 60 sccm He gas 10 sccm (for cooling) Gas pressure: 1.07 Pa Microwave current: 400 mA RF bias: 50 W (2 MHz)

As described above, the aluminum-based material layer 3
2, the sidewall protection film 5 obtained by forward sputtering of the resist mask 4 was formed, while the region not masked by the resist mask 4 was removed, as shown in FIG.

Although the side wall protective film 5 is mainly composed of a carbon-based reaction product such as CCl _x polymer derived from the decomposition product of the resist mask 4, Al constituting the etched aluminum-based material layer 3 is formed. It also incorporates Si, Si, low molecular chlorine compounds and chlorine gas.

Next, etching for removing the side wall protective film 5 was performed. That is, etching was performed in the same chamber as the etching apparatus that performed the etching of the aluminum-based material layer 3 by changing the conditions as described below.

Etching conditions Etching gas: SF ₆ gas 30 sccm Cl ₂ gas 30 sccm He gas 10 sccm (for cooling) Gas pressure: 1.07 Pa Microwave current: 300 mA RF bias: 25 W (2 MHz)

When the side wall protective film was etched under the above conditions, the side wall protective film 5 was removed as shown in FIG.

After that, the resist mask 4 was removed by oxygen plasma ashing. Here, 5
Ashing was performed under the following ashing conditions using a 0-sheet batch type hex type in-line ashing device.

Ashing conditions Gas composition: O ₂ gas 900 sccm Gas pressure: 100 Pa RF bias: 900 W (13.56 MHz)

Further, after the above ashing, RA stripper treatment was performed in order to thoroughly remove the residue. This is a stripping treatment with 96% concentrated nitric acid. This condition is shown below.

RA Stripper Treatment Conditions Treatment Time: 10 minutes Treatment Temperature: Room Temperature Treatment Method: Dip Type After the treatment, pure water and isopropyl alcohol are washed.

When the ashing and RA stripper processing is performed as described above, as shown in FIG.
The mask 4 was sufficiently removed, and the residue derived from the resist mask 4 and the side wall protection film 5 did not remain, and only the aluminum-based material layer 3 having the desired patterning remained on the interlayer insulating film 2.

When the wiring is processed as described above, the resist mask 4 and the side wall protective film 5 can be formed by only performing the ashing and the stripping agent treatment which have been repeated many times in the past.
Was sufficiently removed. Also, the amount of dust is 1 /
It could be reduced to about 10 to 1/100.

[0039]

As is apparent from the above description, when the aluminum-based wiring processing method according to the present invention is applied, the resist mask and the sidewall protection film can be removed efficiently in a short time. Therefore, without damaging the wiring, the time and labor required for the wiring processing step can be saved, and the cost of the manufactured semiconductor device or the like can be reduced.

Further, since the side wall protection film can be sufficiently removed, the generation of dust can be suppressed and the reliability of the work of the next step can be improved. Therefore, the quality of the manufactured semiconductor device or the like can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a process of processing an aluminum-based wiring according to an embodiment, which is a schematic view of a wafer before RIE.

FIG. 2 is a cross-sectional view schematically showing the wafer after processing the aluminum-based material layer of FIG. 1 by RIE.

FIG. 3 is a cross-sectional view schematically showing the wafer after removing the side wall protective film of FIG.

FIG. 4 is a cross-sectional view schematically showing the wafer after removing the resist mask of FIG.

FIG. 5 is a cross-sectional view schematically showing a conventional aluminum-based wiring processing step and schematically showing a wafer before RIE.

6 is a cross-sectional view schematically showing the wafer after processing the aluminum-based material layer of FIG. 5 by RIE.

7 is a cross-sectional view schematically showing a wafer in which a residue is generated after removing the resist mask of FIG.

[Explanation of symbols]

 1 ... Wafer 2 ... Interlayer insulating film 3 ... Aluminum-based material layer 4 ... Resist mask 5 ... Side wall protection film 6 ... Residue

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display part 21/88 D

Claims (4)

[Claims] 1. A step of dry-etching an aluminum-based material layer through a resist mask, and a sidewall protection film deposited on the pattern sidewall surface in the etching, containing at least a fluorine-based compound and a chlorine-based compound. A method for processing an aluminum-based wiring, comprising a step of removing using a gas and a step of removing the resist mask. 2. The etching gas is SF ₆ / Cl
_{2. The} method for processing an aluminum-based wiring according to claim 1, wherein the mixed gas is a mixed gas. 3. The method for processing an aluminum-based wiring according to claim 1, wherein the resist mask is removed by ashing. 4. The method of processing an aluminum-based wiring according to claim 3, further comprising a release agent treatment after the ashing.