JP2746494B2 - Resist removal method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for removing a resist, and more particularly to a method for removing a resist layer used as a mask in dry etching.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view for explaining a resist removing step in a conventional method for manufacturing a semiconductor device, for example. In the figure, reference numeral 3 denotes a film to be etched formed on a base substrate 4 and patterned by dry etching, 1 denotes a resist layer used as a mask when etching the film 3 to be etched, and its surface portion 1a is used for dry etching. The altered part 1a is formed by the chemical reaction of Further, the resist layer 1 and the film to be etched 3
The deposited film 2 is formed on the side surface of the substrate.
Are components formed by decomposition of a resist, components generated from a film to be etched, an etching gas or the like, or products formed by the reaction products thereof. Reference numeral 1b denotes an unaltered portion of the resist inside the altered portion 1a of the resist layer 1.

Next, a manufacturing method will be described. After the film 3 to be etched is formed on the base substrate 4, a resist film is formed on the etching film 3, and the resist film is patterned by a lithography process to form a resist layer 2 having a desired pattern. Thereafter, using the resist layer 2 as a mask, the film-to-be-etched 3 is selectively etched using a chlorine-based or fluorine-based gas or a mixed gas thereof.
As the etching apparatus used at this time, there are an RIE apparatus, a magnetron apparatus and the like.

[0004] An Al (Si) Cu film (thickness: 0.3 to
The etching conditions for etching an Al alloy (2.0 μm) or the like by magnetron RIE are shown. Gas: BCl ₃ , Cl ₂ , SiCl ₄ , BBr ₃ , CF
₄ such as a gas flow rate: 20～200Sccm Pressure: 10~400mT RF Power: 100 to 400 W field: 0～140Gauss Etching time: 30～300Sec gas _{composition: SiCl 4 / Cl 2 / CF} 4 = 20~80 / 20~
80 / 5-20sccm

[0005] When such etching is performed, FIG.
As shown in the figure, the upper surface of the resist layer 1 is deteriorated by irradiation or dissociation from plasma containing an etching gas, for example, a reaction product generated by an etching reaction of ions, radicals, etc. Alternatively, the reaction product or the like may adhere to the side surfaces of the resist layer 1 and the film 3 to be etched to form a deposited film 2.

Thereafter, the resist layer 1 is removed by ashing under the ashing conditions described below. Gas: O ₂ microwave power: 500 to 1500 W Gas flow rate: 1000 to 5000 sccm Pressure: 0.1 to 10 Torr Ashing time: 30 to 120 sec / wafer

At the time of this ashing, the resist layer 1 is concentrated while a part of the resist deteriorated portion 1a generated in the above-mentioned etching process, the deposited film 2 of the reaction product, and the like remain partially. As a result, the non-volatile resist residues 5a and 5b are left. A thread-like non-volatile resist surface residue 5a remains on the upper surface of the patterned film 3 to be etched, and a non-volatile resist side wall residue 5b remains on the side wall of the film 3 to be etched (FIG. 2B).

After that, the resist residue that cannot be removed by ashing with O ₂ plasma or the like is treated by wet etching or the like, but the surface or side surface of the film to be etched 3 is exposed as shown in FIG. Some of the residue 5a and the resist side surface residue 5b remain without being removed.

[0009]

As described above, in the conventional method of removing a resist in a method of manufacturing a semiconductor device, when an ashing process is performed using O ₂ plasma after dry etching, the resist layer 1 is not etched. Only the unaltered portion 1b is ashed without removing the generated resist altered portion 1a and the deposited film 2 of the reaction product, and is finally concentrated to become resist residues 5a and 5b. Therefore, there is a problem that the resist residues 5a and 5b cannot be completely removed even if a wet etching process is subsequently performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to remove a resist layer used as a mask at the time of dry etching without generating a resist residue. An object of the present invention is to provide a method for manufacturing a semiconductor device which can secure a margin against corrosion due to residues.

[0011]

According to a method of removing a resist according to the present invention, after dry etching, as a step of removing a resist layer used as a mask in the etching, the resist is changed by a chemical reaction in the dry etching. A deteriorated portion on the surface of the resist layer, and a deteriorated portion and a deposition for removing a deposited film formed by depositing a reaction product at the time of the dry etching on the surface of the resist layer or the film to be etched under predetermined processing conditions. A film removing step, and then an unaltered portion removing step of removing the unaltered portion of the resist layer under a processing condition different from the processing condition,
Before the removal process in the altered part and deposited film removal process or
Put After removal process, or the undegraded portion removing step
After the removal process , a heating process is performed in a vacuum to evaporate residual components including an etching gas at the time of dry etching.

In the resist removing method according to the present invention, in the step of removing the altered portion and the deposited film, the altered portion and the deposited film on the surface of the resist layer are subjected to ashing treatment with O ₂ plasma to which a trace amount of fluorine-based gas is added. Not yet
In the altered portion removing step, a wet process or an ashing process using O ₂ plasma is performed on the unaltered portion of the resist layer.

[0013]

[0014]

According to the present invention, when the resist layer serving as an etching mask is removed after the dry etching, the altered portion of the surface of the resist layer which is altered by the chemical reaction during the dry etching, and the reaction generated during the dry etching. Since the deposits formed on the surface of the resist layer and the film to be etched are removed beforehand, the residues that cause the residues of the resist generated during the etching are removed before the resist removal treatment. As a result, it is possible to reduce the generation of resist residues in the resist removal process. Ma
Of the step of removing the deteriorated part of the resist layer and the deposited film
Before or after the process, or the resist layer is unchanged
After the step of removing the porous portion, the residual component including the etching gas at the time of dry etching is evaporated by heat treatment in a vacuum, so that when the film to be etched is an aluminum alloy, chlorine, which is a cause of corrosion, is removed . Residual components are reduced, and the occurrence of corrosion in the film to be etched can be suppressed.

[0015]

[0016]

Embodiments of the present invention will be described below. What
For convenience of explanation, first of all, for reference of the embodiment of the present invention,
A reference example will be described. FIG. 1 shows an embodiment of the present invention.
Is a diagram showing a process flow of the resist removal method according to Reference Example as the reference, in FIG, 3 is AlSiCu or AlSi on underlying substrate 4, AlCu such form an aluminum alloy layer, and patterned by dry etching The formed film to be etched, 1 is a resist layer used as a mask at the time of the dry etching, 1a is a deteriorated portion formed by a surface portion of the resist layer 1 being deteriorated by a chemical reaction at the time of etching, and 2 is the resist layer. 1 and a deposition layer formed by depositing a reaction product during the etching on the side surface of the film 3 to be etched.

Next, the manufacturing method will be described. After forming the aluminum alloy layer on the base substrate 4 as in the conventional method,
A resist layer 1 having a predetermined pattern is formed on the aluminum alloy layer by a lithography process, and the aluminum alloy layer is selectively etched using the resist layer 1 as a mask to form a film 3 to be etched (FIG. 1A). ). The etching conditions at this time are shown below.

Etching gas: BCl ₃ , Cl ₂ , Si
Cl ₂ , BBr ₃ , CF _4, etc. Gas flow rate: 20 to 200 sccm Pressure: 10 to 400 mT RF power: 100 to 400 W Magnetic field: 0 to 140 Gauss

Here, as an etching apparatus, for example, R
An IE device, a magnetron RIE device, or the like is used. After the etching, as shown in FIG. 1A, a deteriorated portion 10 is formed on the surface of the resist layer due to a chemical reaction during the etching,
Irradiated or dissociated material from plasma containing etching gas,
That is, a deposited film 2 is formed on the side surfaces of the resist layer 1 and the film 3 to be etched by a reaction product or the like generated from ions, radicals, or the like.

Next, the deteriorated portion 1a of the resist and the deposited film 2 are ashed by, for example, a downflow type asher with O ₂ plasma to which a small amount of an F-based gas is added (FIG. 1 (b)). The ashing conditions at this time are shown below. Gas: O ₂ / CF ₄ Gas composition: O ₂ / CF ₄ = 1000-4000 / 10
1000 sccm microwave power: 500 to 1500 W gas pressure: several to 10 Torr Ashing time: 20 to 40 sec

As described above, the altered portion 1a and the deposit 2 on the surface of the resist layer are removed by adding a small amount of the F-based gas.

Next, the unaltered portion 1b of the resist layer 1 is ashed (FIG. 1 (c)). Ashing at this time is performed under the following conditions using, for example, a downflow type asher.

Gas: O ₂ gas flow rate: O ₂ = 1000-5000 sccm Microwave power: 500-1500 W Ashing time: 20-30 sec

As described above, in the reference example, when removing the resist layer 1 used as a mask during the dry etching of the film 3 to be etched, first, the altered portion 1a on the surface of the resist layer 1 and the film 3 to be etched and the resist layer 1 are removed. The deposited film 2 on the side surface of the resist layer 1 is ashed by O ₂ plasma to which a small amount of an F-based gas is added, and then the unaltered portion 1b of the resist layer 1 is ashed by O ₂ plasma. The residue that causes the residue can be removed, whereby the resist layer 1 can be completely removed.

FIG. 3 is a diagram showing a process flow of a method for removing a resist according to an embodiment of the present invention. In this embodiment, a residue which cannot be completely removed by ashing using O ₂ plasma to which a small amount of an F-based gas is added. It differs from the above reference example in having a step of evaporating the substance.

That is, after the aluminum alloy layer on the base substrate 4 is patterned using the resist layer as a mask in the same manner as in the above-described reference example, the film 3 to be etched is formed (FIG. 1A).
), The deteriorated portion 1a on the surface of the resist layer 1 and the deposited film 2 on the side surface of the resist layer 1 and the film 3 to be etched 3 are treated with a downflow type asher to add a small amount of F-based gas to O _2.
Ashing is removed by plasma (FIG. 3B). The ashing conditions here are the same as in the above-described reference example, as shown below.

Gas: O ₂ / CF ₄ Gas composition: O / CF ₄ = 1000 to 4000/10 to 1000 sccm Microwave power: 500 to 1500 W Gas pressure: several to 10 Torr Ashing time: 20 to 40 sec

Next, the resist layer 1 and the film-to-be-etched 3 are heated in vacuum to evaporate the residue 6 during the etching process, which cannot be completely removed in the ashing step (FIG. 3C). ). The heating conditions at this time are shown below.

Gas: None Gas Pressure: １1 Torr Microwave power: 0 W Substrate temperature: ４００400 ° C. Thereby, the chlorine component remaining on the wafer after etching is reduced, and the occurrence of corrosion is suppressed.

Thereafter, the unaltered portion 1b of the resist layer 1 is ashed using a downflow type asher as in the case of the above reference example, so that the resist layer 1 is completely removed. The ashing conditions at this time are shown below.

Gas: O ₂ gas composition: O ₂ = 1000-5000 sccm μ wave: 500-1500 W Ashing time: 20-sec

[0032] Thus, in the present embodiment, the resist layer 1 of altered portion 1a and the resist layer 1 and O ₂ of the insulating film 2 side of the film to be etched 3 F-based gas dopants used as a mask during dry etching after ashing with a plasma, the resist layer 1 and the etched film 3 is heated in vacuum. Thus evaporate the residue 6 which could not be removed by the ashing process, the effect of the reference example In addition, the chlorine component remaining on the wafer after the dry etching of the film to be etched 3 is reduced, so that the occurrence of corrosion in the film to be etched 3 can be suppressed.

In the above embodiment, the heating of the resist layer 1 and the film 3 to be etched is performed by the altered portion 1a of the resist.
Although the heating is performed immediately after the removal of the deposited film 2, the heating may be performed before the removal of the altered resist portion 1 a and the deposited film 3 or after the removal of the unaltered portion 1 b of the resist layer 1. .

In the above embodiment, ashing with O ₂ plasma was used in the step of removing the unaltered portion 1b of the resist layer 1. However, the ashing may be performed by wet etching. The same effect can be obtained.

Further, in the above embodiment, the case where the film to be etched is an aluminum alloy has been described, but the film to be etched is W, WSi, Doped @ Poly-Si, Ti
N, TiSi ₂ or the like may be used.

[0036]

As described above, according to the resist removing method of the present invention, when removing the resist layer as an etching mask after dry etching, the surface of the resist layer which has been altered by the chemical reaction at the time of dry etching is removed. The deteriorated portion, and a deposition film formed by the reaction product during the dry etching being deposited on the resist layer or the surface of the film to be etched are removed in advance, and in addition, an etching gas at the time of the dry etching by a heat treatment in a vacuum. Since the residual component containing is evaporated, a residue which is a cause of resist residue generated during etching is removed from the resist layer.
Was removed prior to the removal process, it is possible to reduce the occurrence of resist residue, the film to be etched may be aluminum alloy, the residual content of chlorine is reduced is the cause of corrosion, 該被
This has the effect of suppressing the occurrence of corrosion in the etching film .

[0037]

[Brief description of the drawings]

FIG. 1 is a view showing a process flow for explaining a resist removing method according to a reference example serving as a reference of an embodiment of the present invention.

FIG. 2 is a view showing a process flow of a conventional resist removing method.

FIG. 3 is a diagram showing a process flow for explaining a resist removing method according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Resist layer 1a Resist deteriorated part 1b Resist unchanged part 2 Deposited film 3 Film to be etched 4 Base substrate 6 Substance which evaporates by heating

Claims (4)

(57) [Claims] 1. A method for removing a resist layer used as a mask during dry etching, wherein the altered portion of the surface of the resist layer altered by a chemical reaction during the etching, and the reaction product at the time of etching comprise the resist layer and A deteriorated portion and a deposited film removing step of removing a deposited film formed by depositing on the underlayer under predetermined processing conditions; and thereafter, removing an unaltered portion of the resist layer under processing conditions different from the above processing conditions. and a non-degraded portion removing step of removing under, or before the removal process in the altered portion and the deposited film removing step
Put After removal process, or the undegraded portion removing step
A heat treatment in a vacuum after the removal process to evaporate residual components including an etching gas at the time of dry etching. 2. The method according to claim 1, wherein the step of removing the deteriorated portion and the deposited film is a step of ashing the deteriorated portion and the deposited film on the surface of the resist layer with O ₂ plasma to which a slight amount of fluorine-based gas is added. The resist removal method described in the above. 3. The fluorine-based gas is CF ₄ , SF ₆ ,
_{3. The} method for removing a resist according to claim 2, wherein one of NF ₃ and CHF ₃ or a mixed gas thereof is used. 4. The method according to claim 1, wherein the unaltered portion removing step is a step of performing a wet process or an ashing process using O ₂ plasma on the unaltered portion of the resist layer. .