Cleaning and liquid contact with solids – Processes – For metallic – siliceous – or calcareous basework – including...
Reexamination Certificate
1999-01-08
2001-06-19
El-Arini, Zeinab (Department: 1746)
Cleaning and liquid contact with solids
Processes
For metallic, siliceous, or calcareous basework, including...
C134S022100, C134S022120, C134S022180, C134S025100, C134S025400, C134S033000, C134S023000, C134S024000, C134S036000, C134S170000, C134S902000
Reexamination Certificate
active
06248177
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to carriers used in the semi-conductor fabrication industry, and in particular to an apparatus and method of cleaning said carriers.
The process of forming semi-conductor wafers or other delicate electronic components into useful articles require high levels of precision and cleanliness. As these article become increasingly complex and miniaturized, contamination concerns grow. The problems of airborne contamination can be significantly reduced by providing controlled fabrication environments known as clean rooms. While clean rooms effectively remove airborne contaminants found in ambient air, it is often not possible or advisable to completely process wafers in the same clean room environment. Moreover, not all contamination and contaminants are eliminated. For that and other reasons, semi-conductor wafers are transported, stored, and fabricated in bulk with the assistance of protective carriers or pods. These carriers generally include closures which enable the carriers or pods to maintain their own micro-environment. This further reduces the potential from some airborne contaminants.
Contamination and contaminants can generated by other mechanisms. For example, particulates can be generated mechanically by wafers as they are inserted into and removed from wafer carriers, and as doors are attached and removed from the carriers, or they can be generated chemically in reaction to different processing fluids. Contamination can also be the result of out-gassing on the carrier itself, biological in nature due to human activity, or even the result of improper or incomplete washing of the carrier. Contamination can also occur on the exterior of a carrier as the carrier is transported from station to station during processing.
These contaminants and contamination can be reduced by periodically washing and/or cleaning the carriers or pods. Typically, a carrier is cleaned of contaminants and contamination by placing the carrier in a cleaning apparatus which subjects the exterior and interior surfaces to cleaning fluids. Often, the fluids used to clean the exterior surfaces are different from the fluids used to clean the interior surfaces. The expended fluid is usually collected in a common receptacle and discarded. Or a cleaning apparatus will utilize the same cleaning fluids for the exterior and interior surfaces. This allows the expended fluid to be recycled.
There are several problems associated with such carrier cleaners. They use large amounts of material because they do not provide for recycling. With those which do recycle, they are unable to tailor the fluids to the specialized needs of the exterior and interior surface. And they do not provide for door or closure cleaning.
There is a need for a wafer carrier cleaner with minimal cross contamination between exterior and interior surface cleaning fluids, a wafer carrier cleaner which conserves valuable resources, a wafer carrier cleaner with a door cleaning capability, and a wafer carrier cleaner which can operate in a moderately controlled environment.
SUMMARY OF THE INVENTION
The present invention is directed to a semi-conductor wafer carrier cleaner, with the term wafer carrier to be construed as a container which is designed or adapted to hold semi-conductor wafers used in the semiconductor industry. Wafer carrier includes, but is not limited to: conventional H-bar wafer carriers; Front Opening Unified Pods (FOUP); Standard Mechanical Interface Pods (SMIF), wafer carrier door holding fixtures, and other carriers used in the micro-electronic industry for storing, transporting, fabricating, and generally holding small electronic components such as semi-conductor chips, ferrite heads, magnetic resonant read heads, thin film heads, bare dies, bump dies, substrates, optical devices, laser diodes, preforms, and miscellaneous mechanical devices.
The wafer carrier cleaner of the present invention includes dual or parallel fluidic circuits are dedicated to, and designed for applying fluids to different predetermined surfaces of a wafer carrier. That is, the wafer carrier cleaner has separate fluidic circuits for applying fluids from first and second isolated areas of the apparatus to the interior and exterior surfaces of a wafer carrier, respectively; the terms fluid and fluidic encompassing states of matter which are gaseous, liquid, or combinations thereof; i.e., flowable.
Generally, one fluidic circuit supplies fluid to the exterior of a wafer carrier while another fluidic circuit supplies fluid to the interior of a wafer carrier.
Specifically, fluids are used to periodically clean, rinse, dry or otherwise prepare (eg., decontaminate) the interior and exterior surfaces of a wafer carrier. Preferably, the fluids are applied through dedicated sprayers which are movably connected to the fluidic circuits. The fluidic circuits include the necessary and appropriate drains, valves, filters and pumps for the interiorally and exteriorally applied fluids, respectively. The valves enable the fluids in the fluidic circuits to be recycled, combined, purged, or recharged as desired or needed.
A wafer carrier cleaner having the features of the present invention comprises a base upon which a wafer carrier (sans door) or a door holding fixture may be sealingly placed and secured. Broadly speaking, the act of placing a wafer carrier component on the base of the cleaning apparatus (which may include sidewalls and a rear wall to form a fluid tight chamber) creates two isolation areas, with the first isolation area including the interior space defined by the wafer carrier component and the base, and the second isolation area defined as that space which is external to the wafer carrier component. The base has a first aperture and a second aperture which permit access and movement of material into these first and second isolation areas, respectively. The first aperture, over which a wafer carrier is positioned, is configured to permit access to the interior thereof, while the second aperture is located outside of the exterior surface of a wafer carrier. In use, a wafer carrier is placed upon the base such that the access aperture of the carrier is coincident with the first aperture in the base. An optional closure for the wafer carrier cleaner may then be closed. A first or exterior sprayer (connected to a first fluidic circuit) and a second or interior sprayer (connected to a second fluidic circuit) then clean the exterior and interior surface of the carrier, preferably simultaneously.
The exterior sprayer applies relatively clean fluid to the exterior surfaces of a carrier as it rotates thereabout in an oscillating manner. As the expended (used) fluid falls away from the exterior surfaces, it is directed through the second aperture and into the first fluidic circuit. The interior sprayer, on the other hand, applies relatively clean fluid to the interior surface of a carrier by moving the sprayer vertically in a reciprocal manner with respect to the carrier or fixture. As the expended (used) fluid falls away from the interior surfaces, it is directed through the first aperture and into the second fluidic circuit.
Although the exterior sprayer is depicted generally as a tube with a plurality of spaced apertures, the tube configured and arranged to move with respect to the wafer carrier, other forms are envisioned. The exterior sprayer may incorporate ultra and/or mega sonic transducers which facilitate surface preparation. Similarly, the interior sprayer may incorporate ultra and/or mega sonic transducers which facilitate surface preparation.
Alternatively, the fluids may be applied directly to the exterior and interior surfaces by submersion in appropriately designed wet benches. An advantage of the submersion technique is that drying time is substantially reduced.
In an alternative embodiment, multiples of wafer carriers may be prepared concurrently. In the particular case of two wafer carriers, a fixture has been provided to enable the entire wafer carrier and attendant door to be prepared at the s
El-Arini Zeinab
Fluoroware, Inc.
Patterson Thuente Skaar & Christensen P.A.
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