Cleaning and liquid contact with solids – Processes – For metallic – siliceous – or calcareous basework – including...
Patent
1997-06-09
1999-10-12
Warden, Jill
Cleaning and liquid contact with solids
Processes
For metallic, siliceous, or calcareous basework, including...
134 15, 134 30, 134 32, 134 33, 134 34, 134 35, 134 37, 134 991, 1341032, 1341033, 134144, 134151, 134153, 134902, B08B 300
Patent
active
059649526
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for super-cleaning surfaces, and to a device in accordance with the preamble of for executing this method.
BACKGROUND OF THE INVENTION
Conventional cleaning methods are based in immersion of the surface of the article or substrate to be cleaned into a wet bath, filled with detergent for cleaning, and, for instance reinforced by ultrasound, or by immersion of the substrate in vapor atmospheres, or by mechanical treatment of the surface, for instance by brushing, spraying of water or detergent at high pressure from spray nozzles, or by vibrational excitation vibration (megasonic cleaning).
Particularly in chip manufacture, planarization is a process step that is gaining ever greater significance as the miniaturization of structures progresses. The structured surfaces of a substrate (for instance of a silicon wafer) are ground or lapped flat by a chemical-mechanical polishing step (or CMP processing step), using fine grinding agents (slurry). These grinding agents have an extremely small particle size, with the attendant disadvantage that after the grinding process, individual grinding particles still adhere to the machined surface and are partly embedded in the surface. After the grinding process, the surface must be freed completely of grinding agents and other contaminants so that the substrate can be further machined.
As already noted above, by means of brushes, water and by spraying water at high pressures of up to 50 bar, an attempt is made to remove the grinding agent residues. The brushes have the substantial disadvantage that they must be constantly wetted with water and that they gradually fill up with the removed grinding agents. The brushes must therefore be replaced regularly, which in turn has the disadvantage that by intervention with the cleaning station on replacement of the brushes, the cleaning station becomes contaminated. Mechanically treating the surface to be cleaned with the brushes also involves the danger that the surface will become damaged and in particular scratched. As a rule, the cleaning process with the brushes is followed by a further cleaning process in which water is sprayed at high pressure. If good results are to be obtained, the surface to be cleaned must be exposed to the spray for a certain period of time and stopped repeatedly, which makes for a long cleaning time.
The disadvantages of the conventional method will be listed again below. Along with major brush wear and hence high costs for the brushes, frequent brush changing involves a necessary intervention into the machine and hence a machine shutdown. Because the brushes become filled with particles, damage to the surface by scratching must be feared, and the fact that the brushes (the brush material is PFA sponge) are kept permanently wet means major consumption of deionized water. Moreover, designing the cleaning chamber with brush cleaning for cleaning both sides of the substrate is complicated and expensive. The contact pressure of the sponge brushes cannot be adjusted replicably. In high-pressure cleaning, there is the risk of electrostatic charging of the substrate, since nonconductive deionized water is used. With megasonic cleaning, the surface cannot be cleaned completely, especially after grinding processes.
From European Patent Disclosure EP0381435A2, a method and a device for washing printed circuit boards is known. Steam is sprayed at the boards at a temperature and a pressure at which the steam undergoes no change of phase.
Japanese reference JP-A 703 7866 discloses a device with which an article is exposed to an atmosphere of steam enriched with NO.sub.2.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a method and/or a device available, by means of which contaminated surfaces can be cleaned more simply, at lower cost and more rapidly, as well as with increased protection from damage.
This object is attained in accordance with the present invention in that in the method aspect at least one steam noz
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Carrillo S.
Warden Jill
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