Semiconductor device manufacturing: process – Chemical etching – Combined with the removal of material by nonchemical means
Reexamination Certificate
2000-09-13
2002-08-27
Webb, Gregory E. (Department: 1751)
Semiconductor device manufacturing: process
Chemical etching
Combined with the removal of material by nonchemical means
C510S175000, C510S176000, C510S177000, C438S638000, C438S624000, C438S690000, C438S692000
Reexamination Certificate
active
06440856
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a cleaning agent for semiconductor parts and a method for cleaning the semiconductor parts, and more particularly to a cleaning agent used for cleaning surfaces of semiconductor parts such as semiconductor substrates, and a method for cleaning the semiconductor parts.
BACKGROUND OF THE INVENTION
As new planarization technology in the manufacturing processes of semiconductor devices, chemical mechanical polishing (CMP) has attracted attention. The CMP has the advantage of being able to shorten the steps and of being difficult to be affected by the pattern dependency to achieve good planarization, compared with conventional reflowing processes and etch back processes such as RIE (reactive ion etching). This type of CMP has been applied to, for example, metal planarization in multiple layers and planarization of interlayer insulation films.
As methods for cleaning substrate after the chemical mechanical polishing as the planarization process of interlayer insulation films, various methods have been proposed. Highest in versatility is RCA cleaning commonly used in the semiconductor manufacturing processes. The RCA cleaning comprises a cleaning step using a mixed solution of ammonia, aqueous hydrogen peroxide and water, and a cleaning step using a mixed solution of hydrochloric acid, aqueous hydrogen peroxide and water.
In etching surfaces of interlayer insulation films with diluted hydrofluoric acid, or in using alkali abrasives, methods of conducting acid cleaning are also proposed. It is most frequently used at present as the after treatment in the chemical mechanical polishing (CMP) process that after brush scrub cleaning, SC1 cleaning is carried out with, for example, an alkaline cleaning agent having an ammonia/hydrogen peroxide/water weight ratio of 1:1:5 to remove particles which have adhered to surfaces of substrates in the polishing process.
Further, for cleaning metallic impurities adsorbed by the surfaces of the substrates after CMP, it is known that an aqueous solution of citric acid is used, and further that an aqueous solution of citric acid or ethylenediaminetetraacetic acid (EDTA) is used together with hydrogen fluoride. Cleaning agents containing organic acids such as citric acid and complexing agents are also known in the art.
However, according to the above-mentioned cleaning agents, it is difficult to remove metallic impurities and abrasive particles left on the substrates after the chemical mechanical polishing, to a level at which no problem is encountered. For achieving an adequate cleaning effect, it is necessary to increase the concentration of the cleaning agents, which causes the problem of an increased load on the environment such as the liquid waste disposal.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a cleaning agent decreased in a load on the environment, and having a high cleaning effect on CMP (chemical mechanical polishing) abrasive particles such as silica and alumina, metallic impurities contained in the CMP slurry, or impurities such as Fe, Mn, Al, Ce, Cu, W and Ti derived from metallic wiring, which are left on semiconductor parts such as semiconductor substrates after the CMP.
Another object of the invention is to provide a method for cleaning semiconductor parts with the above-mentioned cleaning agent.
According to one aspect of the invention, there is provided a cleaning agent for semiconductor parts comprising a (co)polymer having at least one kind of group selected from the group consisting of sulfonic acid (salt) groups and carboxylic acid (salt) groups.
The above-mentioned (co)polymer is preferably one obtained by (co)polymerizing at least one kind of monomer selected from the group consisting of sulfonic acid (salt) group-containing monomers (a) and carboxylic acid (salt) group-containing monomers (b).
Further, the above-mentioned sulfonic acid (salt) group-containing monomer (a) is preferably at least one kind of monomer selected from the group consisting of 2-methyl-1,3-butadiene-1-sulfonic acid and salts thereof, and (meth)acrylamido-2-methylpropanesulfonic acid and salts thereof.
Still further, the above-mentioned carboxylic acid (salt) group-containing monomer (b) is preferably itaconic acid or a salt thereof.
Yet still further, the ratio of the carboxylic acid group-containing monomer (b) contained in the above-mentioned (co)polymer is preferably less than 20 mole percent.
Furthermore, the above-mentioned (co)polymer is preferably a copolymer having a block structure.
Moreover, it is preferred that the above-mentioned (co)polymer comprises a (co)polymer in which at least one kind of monomer (c) selected from the group consisting of phosphonic acid (salt) group-containing monomers, hydroxyl group-containing monomers, monomers having skeletons derived from ethylene oxide and monomers having skeletons derived from propylene oxide is copolymerized.
The above-mentioned cleaning agent for semiconductor parts preferably contains a phosphonic acid compound.
In addition, it is preferred that the above-mentioned cleaning agent for semiconductor parts contains at least one kind of surfactant selected from the group consisting of anionic surfactants, cationic surfactants and nonionic surfactants.
The above-mentioned cleaning agent for semiconductor parts is preferably used for cleaning the semiconductor parts before and/or after chemical mechanical polishing.
According to the other aspect of the invention, there is provided a method for cleaning semiconductor parts comprising cleaning the semiconductor parts with the above-mentioned cleaning agent.
DETAILED DESCRIPTION OF THE INVENTION
The (co)polymer contained in the cleaning agent for semiconductor parts of the invention and having at least one kind of group selected from the group consisting of sulfonic acid (salt) groups and carboxylic acid (salt) groups can be obtained by, for example, (co)polymerizing at least one kind of monomer selected from the group consisting of sulfonic acid (salt) group-containing monomers (a) and carboxylic acid (salt) group-containing monomers (b). The term “sulfonic acid (salt) group” as used herein means a sulfonic acid group or a salt thereof in which a cationic species is coordinated to the sulfonic acid. Similarly, the term “carboxylic acid (salt) group” as used herein means a carboxylic acid group or a salt thereof in which a cationic species is coordinated to the carboxylic acid, and the term “phosphonic acid (salt) group” as used herein means a phosphonic acid group or a salt thereof in which a cationic species is coordinated to the phosphonic acid.
The (co)polymer of the invention may be any of a sulfonic acid (salt) group-containing (co)polymer, a carboxylic acid (salt) group-containing (co)polymer and a sulfonic acid (salt) group and carboxylic acid (salt) group-containing (co)polymer, and may be a combination of these (co)polymers.
Further, the (co)polymer of the invention includes a (co)polymer salt in which a sulfonic acid group or a carboxylic acid group forms a salt. Therefore the (co)polymer or a salt thereof is also referred to a “(co)polymer (salt)”.
There is no particular limitation on the sulfonic acid (salt) group-containing monomers (a), as long as they are monomers containing sulfonic acid (salt) groups and having polymerizable double bonds. Examples of the monomers (a) include 2-methyl-1,3-butadiene-1-sulfonic acid and salts thereof; (meth)acrylamido-2-methylpropanesulfonic acid and salts thereof; sulfonic acids of conjugated dienes represented by the following general formula (I) and salts thereof (for example, 2-methyl-1,3-butadiene-1-sulfonic acid and salts thereof):
wherein R
1
to R
6
are hydrogen atoms, alkyl groups each having 1 to 8 carbon atoms, aryl groups each having 6 to 20 carbon atoms or —SO
3
X, wherein X is a hydrogen atom, a metal atom, an ammonium group or an amino group, and at least one of R
1
to R
6
is —SO
3
X; unsaturated (meth)allyl ether sulfonic acids represented by the following general formula (II) and salts thereo
Bessho Keiichi
Higami Makoto
Ishikawa Katsuhiro
Ono Hisao
JSR Corporation
Webb Gregory E.
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