Brushing – scrubbing – and general cleaning – Machines – Brushing
Utility Patent
1998-05-14
2001-01-02
Warden, Sr., Robert J. (Department: 1744)
Brushing, scrubbing, and general cleaning
Machines
Brushing
C015S088300, C015S102000, C015S302000, C134S090000, C134S095200, C134S172000, C134S199000
Utility Patent
active
06167583
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor wafer cleaning apparatus and, more particularly, to an apparatus for cleaning the upper and lower surfaces of a semiconductor wafer.
In the wafer processing steps of forming semiconductor elements, e.g., integrated circuits, on a semiconductor wafer, much effort is paid to remove dust attaching to the surface of the wafer.
For this purpose, the semiconductor wafer is cleaned by using, e.g., pure water, ultrapure water, or electrolytic ionized water obtained by electrolyzing pure water or ultrapure water. Although a fluorine-based solvent, e.g., flon, was previously used to clean the semiconductor wafer, it has been avoided recently as it adversely influences the environment, and water such as pure water or ultrapure water has begun to be utilized as the solvent.
Pure water refers to high-purity water having a resistivity of about 5 M&OHgr;cm to 18 M&OHgr;cm, from which impurities such as ions, fine particles, germs, organic substances, and the like are almost removed. Ultrapure water refers to very high-purity water manufactured by highly efficiently removing suspended materials and dissolved materials from pure water. When such water (pure water and ultrapure water will be generally called pure water hereinafter) is electrolyzed, electrolytic ionized water, e.g., anode ionized water (acid water) having high oxidizing properties and cathode ionized water (alkali water) having high reducing properties can be generated.
To clean the semiconductor wafer, the wafer is held on a vacuum chuck type spin chuck and is rotated. In this state, a cleaning liquid is dropped onto a rotating roll-like brush. The roll-like brush comes into contact with the semiconductor wafer to remove dust attaching to it. Thereafter, dropping of the cleaning liquid is stopped, and the semiconductor wafer is rotated at a high speed, thereby drying the surface of the semiconductor wafer.
According to the cleaning method described above, dust on the surface of the semiconductor wafer where the active region is formed can be removed. However, as the integration degree of the semiconductor integrated circuit devices, e.g., ICs and LSIs, increases, the integrated circuits are micropatterned at a higher density. In the step such as photolithography or etching, the influence of even dust on the lower or side surface of the semiconductor wafer on the process cannot be neglected.
As a countermeasure for this, the upper and lower surfaces of the semiconductor wafer may be cleaned simultaneously. Since a semiconductor wafer during cleaning must be held by some means, it is difficult to sufficiently clean its upper and lower surfaces. In a conventional roll type single wafer cleaning apparatus, cleaning is performed by supplying processing liquids, e.g., chemicals and pure water, from the outer circumferences of the rolls. Therefore roll clogging and counter contamination caused by the rolls pose a problem. In addition, to dry the wafer, the wafer must be moved to a dry stage, leading to a complicated, large apparatus.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide a double side cleaning apparatus for a semiconductor substrate capable of effectively removing, while processing the semiconductor substrate, dust attaching to the upper and lower surfaces of the semiconductor substrate, within a short period of time.
It is another object of the present invention to provide a double side cleaning apparatus capable of not only cleaning the semiconductor substrate but also drying the cleaned semiconductor substrate quickly without contaminating it.
It is still another object of the present invention to provide a double side cleaning apparatus capable of cleaning not only the upper and lower surfaces but also the side surface of the semiconductor substrate effectively.
In order to achieve the above objects, according to the first aspect of the present invention, there is provided an apparatus for cleaning upper and lower surfaces of a semiconductor substrate, comprising:
a semiconductor holding mechanism for holding the semiconductor substrate;
a pair of roll-like brushes rotatably arranged to sandwich the semiconductor substrate not to be in contact therewith and made of a porous material having hollow portions; and
a processing liquid supply device for supplying a high-pressure processing liquid into the hollow portions of the roll-like brushes and blowing the processing liquid toward the upper and lower surfaces of the semiconductor substrate at substantially equal pressures from outer surfaces of the roll-like brushes, thereby cleaning the upper and lower surfaces of the semiconductor substrate simultaneously.
With this arrangement, the upper and lower surfaces of the semiconductor wafer can be cleaned simultaneously and effectively.
The second aspect of the present invention has, in addition to the arrangement of the first aspect, a side surface cleaning brush. This side surface cleaning brush abuts against an edge portion of the semiconductor substrate, while the upper and lower surfaces of the semiconductor substrate are being cleaned with the roll-like cleaning brushes, to clean a side surface of the semiconductor substrate.
With this arrangement, not only the upper and lower surfaces but also the side surface of the semiconductor substrate, which is not cleaned conventionally, can be cleaned. This improves the reliability of the semiconductor processing steps.
The third aspect of the present invention has, in addition to the arrangement of the first aspect, a pressure reducing unit for reducing a pressure in the hollow portions of the roll-like brushes. The hollow portions are pressure-reduced with the pressure reducing unit to attract the upper and lower surfaces of the semiconductor substrate, thereby drying the semiconductor substrate.
With this arrangement, one apparatus can perform a series of processing operations starting from cleaning and ended with drying, so that the cleaning efficiency is improved. Since the number of steps is decreased, the risk of contaminating the semiconductor substrate can be reduced.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinbefore.
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European Search Report, August 7, 2000 (pp. 1-3).
Abe Masahiro
Miyashita Naoto
Finnegan, Henderson, Farabow, Garrett & Dunner, L.LP.
Kabushiki Kaisha Toshiba
Olsen Kaj K.
Warden, Sr. Robert J.
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