Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
1999-10-25
2001-10-30
Le, Hoa Van (Department: 1752)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C430S331000
Reexamination Certificate
active
06310020
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a stripping composition for a resist (hereinafter simply referred to as “stripping composition”), and more specifically to a liquid stripping composition for stripping a resist in the lithography in technical fields such as semiconductor devices and LCD.
2. Discussion of the Related Art
In the production of semiconductor devices, LCD, and the like, there has been employed a process of completely stripping the resist comprising forming a conductive film or insulating film onto a substrate by PVD (physical vapor deposition) or CVD (chemical vapor deposition); forming the desired patterns for resist on a thin film by lithography; and selectively etching the lower layer portion of the thin film as an etching resist to strip the formed patterns. In this process, the amine compounds are often used as a stripper.
However, as the integration rate of the semiconductor devices is increased, in order to further improve the working accuracy of the substrate after the formation of the resist film, there has been generally developed to raise the post-baking temperature of the resist film after development or to implement working techniques such as plasma etching, reactive ion etching (RIE treatment), and ion implantation. Therefore, it has been extremely difficult to strip with the conventional stripper the resist film which is modified or hardened owing to the high-energy treatments applied.
In addition, in the stripper comprising the amine stripper, when the content of the amine compound or water is high, the pH of the stripper becomes high, so that the corrosion against a metal wiring or metal thin film of aluminum or tungsten on a substrate is likely to take place, thereby having a defect that the metal surface is faded or dissolved.
As a stripper for solving these defects, there have been proposed, for instance, a stripping composition prepared by adding a carboxyl group-containing organic compound to a nitrogen-containing organic hydroxy compound, which is an amine compound (Japanese Patent Laid-Open No. Hei 7-219240); a stripping composition comprising an organic acid such as acetic acid, lactic acid, or hydroxyacetatic acid, benzyl alcohols, and 75 to 99% by weight of water as essential components (Japanese Patent Laid-Open No. Hei 4-361265). In any of the above stripping compositions, the stripping ability and the capability of preventing corrosion are insufficient.
An object of the present invention is to provide a stripper composition having excellent stripping ability even against a modified or hardened resist by applying high-energy treatment, and excellent capability of preventing corrosion against various parts such as metal wiring or metal thin films on semiconductor devices and LCD, and a method for stripping a resist therewith.
This and other objects of the present invention will be apparent from the following description.
SUMMARY OF THE INVENTION
The present invention pertains to:
[1] a stripping composition for a resist comprising a polycarboxylic acid and/or a salt thereof, and water, wherein a pH of the stripping composition is less than 8;
[2] a stripping composition for a resist comprising:
0.01 to 90% by weight of an organic acid and/or a salt thereof,
2 to 74% by weight of water, and
0.5 to 90% by weight of an organic solvent,
wherein a pH of the stripping composition is less than 8; and
[3] a method of stripping a resist from a substrate, comprising applying the stripping composition of item [1] or [2] to the substrate.
DETAILED DESCRIPTION OF THE INVENTION
The stripping composition for a resist of the present invention can exhibit excellent stripping ability by the use of a polycarboxylic acid or a salt thereof and water. In this case, an organic solvent may be further added thereto, whereby a more remarkable stripping effect can be achieved. The synergistic effect with the organic solvent mentioned above is not limited to a polycarboxylic acid or a salt thereof, and organic acids such as monocarboxylic acids are included, and a more excellent stripping ability is exhibited by the addition of a desired amount. In addition, in the composition of the present invention, a stripping composition for a resist having excellent capability of preventing corrosion by further adding a compound containing Si atom in a molecule.
Therefore, the preferred embodiments of the stripping composition for a resist of the present invention can be roughly classified into two embodiments:
[Embodiment a] a stripping composition comprising a polycarboxylic acid and/or a salt thereof and water, preferably further comprising an organic solvent and/or a compound containing Si atom in a molecule, wherein the pH of the stripping composition is less than 8; and
[Embodiment b] a stripping composition comprising 0.01 to 90% by weight of an organic acid and/or a salt thereof and 2 to 74% by weight of water, and 0.5 to 90% by weight of an organic solvent, preferably further comprising a compound containing Si atom in a molecule, wherein the pH of the stripping composition is less than 8.
It is preferable that the polycarboxylic acid used in Embodiment a is represented by the formula (I):
B—[(R
1
)
p
—(COOH)
q
]
r
(1)
wherein R
1
is linear, branched or cyclic, saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, which may have 1 to 5 oxygen atoms, nitrogen atoms or sulfur atoms, and hydrogen atom bound to a carbon atom of R
1
may be substituted by —OH group, —NH
2
group, —SH group or —NO
2
group; one or more —COOH groups may be bound to the same carbon atom in R
1
; p is 0 or 1; q is an integer of from 1 to 40; r is an integer of from 1 to 3; a sum of q and r is 3 or more; B is absent or is —O—group, —CO—group, —NH— group, —group — or
group.
In the formula (I), R
1
is more preferably a hydrocarbon group having 1 to 10 carbon atoms, and particularly preferably a linear, saturated hydrocarbon group having 1 to 4 carbon atoms. q is more preferably an integer of from 1 to 5, particularly preferably 1 or 2, from the viewpoint of the ability of stripping the resist.
Concrete examples of the polycarboxylic acid represented by the formula (I) include saturated polycarboxylic acids, such as oxalic acid, malonic acid, methylmalonic acid, ethylmalonic acid, dimethylmalonic acid, succinic acid, methylsuccinic acid, 2,2-dimethylsuccinic acid, glutaric acid, adipic acid, 3-methyladipic acid, sebacic acid, hexadecanedionic acid, 1,2,3-propanetricarboxylic acid, 1,2,3,4-butanetetracarboxylic acid, polyacrylic acids, and polymaleic acids; unsaturated polycarboxylic acids such as maleic acid, fumaric acid, citraconic acid, mesaconic acid, cis-aconitic acid, and trans-aconitic acid; hydroxypolycarboxylic acids such as tartaric acid, malic acid, and citric acid; aminopolycarboxylic acids such as aspartic acid and glutamic acid; polycarboxylic acids having an aromatic ring such as terephthalic acid, trimellitic acid, and naphthoic acid; polycarboxylic acids having an alicyclic ring such as 1,2-cyclohexanedicarboxylic acid; polycarboxylic acids having a heterocyclic ring such as 2,3-pyrazinedicarboxylic acid, and the like. Among them, from the viewpoint of the ability of stripping a resist, saturated polycarboxylic acids, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, polyacrylic acids, and polymaleic acids; hydroxypolycarboxylic acids such as tartaric acid, malic acid, and citric acid; and aminopolycarboxylic acids such as aspartic acid and glutamic acid are particularly preferable.
The dissociation index pK
1
at first step of the polycarboxylic acid is preferably 3.6 or less, more preferably from 1 to 3, from the viewpoint of the ability of stripping a resist.
Here, the dissociation index pK
1
at the first step of the polycarboxylic acid is calculated as follows. Specifically, the polycarboxylic acid (represented by H
n
A as the general formula), when dissolved in water, is stepwise di
Kashihara Eiji
Kitazawa Kozo
Nagoshi Eiji
Shirota Mami
Birch & Stewart Kolasch & Birch, LLP
Kao Corporation
Le Hoa Van
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