Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – With metal-corrosion inhibiting component
Reexamination Certificate
2000-01-18
2001-03-13
Gupta, Yogendra (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
With metal-corrosion inhibiting component
C510S175000, C510S176000, C134S002000, C134S003000
Reexamination Certificate
active
06200947
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a metal-corrosion inhibitor and a cleaning liquid. More specifically, the present invention relates to a metal-corrosion inhibitor and a cleaning liquid, which are useful for cleaning materials such as semiconductor devices.
BACKGROUND OF THE INVENTION
In a conventional wiring formation for semiconductor devices, it is general that a metal to be formed into a wiring is applied on a silicon wafer to form a film thereof, and the film is shaped into a desired wiring through lithography and dry etching, and thereafter spaces between the wiring are buried with an insulation film to perform the wiring formation. Recently, there has been developed a chemical mechanical polishing with use of both a special polishing agent and a polishing pad, which is hereinafter abbreviated as CMP, as the case may be, and a wiring formation by damascene process utilizing CMP has been paid attention. According to this method, an insulation film is formed first of all, and thereafter, a groove for the wiring is formed through lithography and dry etching, a metal is applied thereto to form a film thereof and bury the groove therewith, and then CMP is carried out to remove the metal film jutted out from the groove.
However, in the metal wiring formation utilizing CMP, both the surface and the back of a wafer are markedly contaminated with the polishing agent remaining after the metal polishing, a polishing scrap produced by the polishing and metal impurities contained in the polishing agent and the polishing pad, and therefore it is inevitable to clean the surface thereof after the polishing.
In general, in order to remove particles present on a wafer surface, it is desired to carrying out a cleaning with an alkaline solution, because it is important to inhibit re-adhesion of particles once removed out of the surface thereof. While, in order to remove metal impurities effectively, it is desired to carry out the cleaning with an acid solution having a strong metal dissolution power.
However, as is known, a metal is subject to corrosion with these alkaline and acid solutions. Therefore, in the case where the wafer surface on which the metal wiring lays bare is cleaned with these solutions, there is usually caused a problem such that the metal surface after the cleaning is subjected to corrosion, thereby causing increase of a wiring resistance and moreover a breaking down of the wiring.
As a corrosion inhibitor to avoid the metal-corrosion, there are known aromatic hydrocarbon compounds such as, for example, benzotriazole and 5-methylbenzimidazole, and an attempt to use these corrosion inhibitors has been made. Meanwhile, an influence upon human health and the ecological system suffered by various chemical substances discharged to surroundings is now examined. Thus, a metal-corrosion inhibitor less than that so far in use in the possibility of affecting human health and the ecologrical system through a water medium is desired to be developed.
SUMMARY OF THE INVENTION
The present inventors have undertaken extensive studies to find a metal-corrosion inhibitor freed from the aforementioned problem. As a result, it has been found that a compound having a carbon atom bonded with a mercapto group and another carbon atom bonded with a hydroxyl group, which are contiguously bonded with each other, is possessed of no metal-corrosion activity, and suitable for cleaning materials such as semiconductor devices, and moreover less than that so far in use in the possibility of affecting human health and the ecological system through a water medium, and thereby the present invention has been completed.
The present invention provides a metal-corrosion inhibitor comprising an aliphatic alcohol compound having at least one mercapto group in the molecule, wherein a number of carbon atoms constituting said alcohol compound is not less than 2, and a carbon atom bonded with a mercato group and another carbon atom bonded with a hydroxyl group are contiguously bonded with each other.
The present invention further provides a cleaning liquid comprising the aforementioned metal-corrosion inhibitor.
The present invention furthermore provides a process for cleaning semiconductor devices, which comprises contacting said devices with the aforementioned cleaning liquid.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The corrosion inhibitor in accordance with the present invention comprises an aliphatic alcohol compound having at least one mercapto group in the molecule. It is essential for the aliphatic alcohol that a number of carbon atoms is not less than 2, and a carbon atom bonded with a mercapto group and another carbon atom bonded with a hydroxyl group are contiguously bonded with each other, in other words, both the carbon atoms are directly bonded with each other, thereby obtaining a desired corrosion inhibiting effect. Preferred examples of the aliphatic alcohol compound are 2-mercaptoethanol and thioglycerol.
The corrosion inhibitor in accordance with the present invention can inhibit metal-corrosion. Said metal includes, for example, copper and copper alloys.
The corrosion inhibitor in accordance with the present invention can be incorporated into a cleaning liquid to provide a cleaning liquid having no corrosion. activity. As the cleaning liquid, those used for cleaning semiconductor devices are enumerated. Particularly when the cleaning liquid having no corrosion activity is used for cleaning semiconductor devices having a copper wiring, the characteristic features of the present invention can be exhibited. The cleaning liquid can be used in any form of an alkaline solution or an acid solution.
A concentration of the corrosion inhibitor in the cleaning liquid is preferably from about 0.0001 to about 10% by weight, more preferably from about 0.001 to about 1% by weight. When the concentration is too low, the corrosion inhibiting effect may be limited to an unsatisfactory degree. Whereas, too high concentration may not always give a further increased corrosion inhibiting effect and moreover may make difficult to handle it due to the odor peculiar to mercapto group-carrying compounds.
The cleaning liquid can be prepared easily by incorporating the corrosion inhibitor in accordance with the present invention into a conventional cleaning liquid and stirring the mixture to dissolve the corrosion inhibitor therein.
A cleaning with use of the cleaning liquid in accordance with the present invention is not particularly limited, and can be carried out in a conventional manner.
As the cleaning liquid to be incorporated with the aforementioned corrosion inhibitor, it is recommended to use an alkaline solution which is effective for removing fine particles present on a wafer with detrimental effect of causing copper wiring-corrosion easily, and an acid solution which is effective for removing metal impurities on a wafer with detrimental effect of causing copper wiring-corrosion easily.
The alkaline solution is not particularly limited, and includes, for example, aqueous solutions of inorganic compounds such as sodium hydroxide, potassium hydroxide and ammonium hydroxide, and aqueous solution of organic compounds such as tetramethylammonium hydroxide and choline. Particularly, it is recommended to use aqueous solutions of compounds such as ammonium hydroxide, tetramethylammonium hydroxide and choline, which have been purified to remove the metal impurities and fine particles.
The acid solution is not particularly limited, and includes, for example, aqueous solution of inorganic acids such as hydrochloric acid, hydrofluoric acid, sulfuric acid and nitric acid, and aqueous solution of organic acids such as oxalic acid, citric acid, malonic acid, malic acid, fumaric acid and maleic acid. Particularly, it is recommended to use aqueous solutions of acids such as hydrochloric acid, hydrofluoric acid, sulfuric acid, nitric acid, oxalic acid and citric acid, which have been purified to remove the metal impurities and fine particles.
A concentration of the alkaline solution or acid solution
Sawara Kenichi
Takashima Masayuki
Birch & Stewart Kolasch & Birch, LLP
Gupta Yogendra
Petruncio John M.
Sumitomo Chemical Company Limited
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