Cleaning and liquid contact with solids – Apparatus – With movable means to cause fluid motion
Reexamination Certificate
1998-11-11
2001-04-24
Stinson, Frankie L. (Department: 1746)
Cleaning and liquid contact with solids
Apparatus
With movable means to cause fluid motion
C134S186000, C134S902000
Reexamination Certificate
active
06220259
ABSTRACT:
BACKGROUND OF THE INVENTION
Conventional megasonic cleaning tanks employ a fluid filled tank having substrate supports therein and a source of megasonic energy, (e.g., a transducer) coupled to the fluid for directing sonic energy through the fluid to the surfaces of a substrate or wafer supported therein. During megasonic cleaning, the transducer oscillates between a positive and a negative position at a megasonic rate so as to generate positive and negative pressures within the fluid (and thereby coupling megasonic energy to the fluid. As the energy imparted to the fluid oscillates between positive and negative pressure, cavitation bubbles form in the liquid during negative pressure and collapse or shrink during positive pressure. This bubble oscillation and collapse gently cleans the surface of the wafer.
Particles cleaned from the wafer are carried upward via a laminar flow of fluid and flushed into overflow weirs coupled to the top of the cleaning tank. Thus, a supply of clean fluid is continually introduced to the cleaning tank from the bottom of the side walls thereof. Cleaning fluid distribution nozzles are positioned along the bottom of the sidewalls to supply various cleaning fluids through the same nozzles or through dedicated sets of nozzles.
Most conventional cleaning tanks position one or more transducers along the bottom of the cleaning tank. Acoustic waves from these transducers reflect from the surface of cleaning fluid back into transducers, and interference results in reduced power density in the tank and reduced cleaning efficiency. Due to the limited area of the tank's bottom, the number, size, placement and shape of the transducers, fluid inlets, etc., often can not be freely selected for optimal performance. Particularly, positioning the transducer elsewhere would allow a higher laminar flow of fluid from the fluid inlets, and would decrease cleaning/processing time.
Accordingly, a need exists for an improved sonic cleaning tank that provides high laminar fluid flow yet avoids the interference of incident and reflected waves.
SUMMARY
The present invention provides a sonic cleaning tank having a side wall transducer and having a cleaning tank configured to reflect sonic waves away from the wafer, and to thereby avoid interference . Specifically, sonic waves are reflected out of the plane of the wafer, and thereafter undergo further reflection. By generating a plurality of reflections within the tank, the inventive tank design ensures that any reflected wave which impacts the wafer is sufficiently attenuated to avoid the negative effects of interference.
In a first aspect of the invention, a transducer is mounted on a first wall of the cleaning tank, a substrate receiving area is provided for supporting a substrate in parallel with energy wave rays emitted from the transducer and a second wall is located across the substrate receiving area from the first wall, and is angled such that energy wave rays emitted by the transducer impact the second wall and reflect out of the plane of the wafer. Preferably the second wall is angled to form a vertical V.
In a second aspect of the invention, one or more internal partitions extend from the first wall forming one or more partitioned regions to partition energy wave rays which impact the second wall and reflect out of the plane of the wafer.
In a third aspect, the second wall is angled to form a vertical V, and the angle of the V and the position of a side wall (coupled between the first and second walls) relative to the V are such that energy wave rays reflect from the V to the side wall and reflect from the side wall upwardly toward an air/liquid interface of the tank.
Other aspects of the invention position the apex of the second wall's V toward or away from the wafer and/or in line with the wafer or inline with an internal partition, to achieve desired reflection paths.
The various aspects of the invention provide a cleaning tank that is virtually free of interference from reflected energy wave rays yet maintains an open bottom for high laminar fluid flow. The resultant cleaning tank boasts high transducer efficiency and faster cleaning times due to the combination of transducer efficiency and high laminar flow.
Other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiments, the appended claims and the accompanying drawings.
REFERENCES:
patent: 2950725 (1960-08-01), Jacke et al.
patent: 2987068 (1961-06-01), Branson
patent: 3001532 (1961-09-01), Plassmeyer
patent: 3873071 (1975-03-01), Tatebe
patent: 4167424 (1979-09-01), Jubenville et al.
patent: 4170241 (1979-10-01), Clapp
patent: 4224110 (1980-09-01), McCord
patent: 4543130 (1985-09-01), Shwartzman
patent: 5279316 (1994-01-01), Miranda
patent: 5379785 (1995-01-01), Ohmori et al.
patent: 5579792 (1996-12-01), Stanasolovich et al.
patent: 5762084 (1998-06-01), Krusell et al.
patent: 5849091 (1998-12-01), Skrovan et al.
patent: 146936 (1967-03-01), None
patent: 54-103265 (1979-08-01), None
patent: 04049619 (1992-02-01), None
patent: 04196219 (1992-07-01), None
Brown Brian J.
Fishkin Boris
Applied Materials Inc.
Dugan & Dugan
Stinson Frankie L.
LandOfFree
Tank design for sonic wafer cleaning does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tank design for sonic wafer cleaning, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tank design for sonic wafer cleaning will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2546021