Cleaning and liquid contact with solids – Processes – Including use of vacuum – suction – or inert atmosphere
Reexamination Certificate
2001-01-22
2002-12-31
Snider, Theresa T. (Department: 1744)
Cleaning and liquid contact with solids
Processes
Including use of vacuum, suction, or inert atmosphere
C015S301000, C015S345000
Reexamination Certificate
active
06500272
ABSTRACT:
FIELD OF INVENTION
The present invention relates generally to the field of equipment maintenance. More particularly, the present invention is directed to a system for and method of purging/venting a rotational bearing of a semiconductor wafer-cleaning brush arm assembly to prevent foreign material from fouling the bearing.
BACKGROUND OF THE INVENTION
During the manufacturing of semiconductor devices, substrate wafers are subject to a number of processes that form multiple film layers upon one face of the wafer. These layers are made of one or more materials that, when arranged in a predetermined pattern, form parts of the microelectronic components of the devices. At various stages of wafer processing, the surface of the wafer must be polished to produce a uniformly smooth surface across the entire wafer. This polishing is typically accomplished by chemical mechanical polishing, a process that utilizes a chemical slurry in combination with a mechanical polisher to polish the wafer surface.
Immediately after polishing, the wafer is contaminated with the chemical slurry and other foreign material, such as particles removed from the surface of the wafer during polishing. Before the wafer can undergo further processing, e.g., deposition of another film layer, the wafer must be cleaned of the contaminants. Typically, the wafer is cleaned in a dedicated post-chemical mechanical polishing cleaning machine having a chamber for cleaning the backside of the wafer and a chamber for ultra-cleaning the processed surface of the wafer.
The processed surface cleaning chamber includes a rotating brush mounted on a brush arm. To clean the processed surface of the wafer, the wafer is mounted in a chuck within the cleaning chamber. The brush arm is then moved so that the rotating brush is brought into contact with the processed surface. The brush then makes several passes over the processed surface to remove the contaminants while de-ionized water is sprayed onto the wafer from a plurality of directions.
Generally, the brush arm comprises an elongate body having first and second ends spaced from one another. The rotating brush is located at the first end and a drive shaft for driving the rotating brush is located at the second end. The rotating brush is mounted in a first cavity at the first end of the brush arm via a rotational bearing. A drive belt extends between the drive shaft and the rotational bearing within a second cavity. The first and second cavities are prone to invasion by water and other foreign material from the ambient environment surrounding the brush arm through seals at the drive shaft and the rotational bearing. The first and second cavities are also prone to condensation problems from moist air trapped within them.
Moisture from water invasion and condensation frequently damages the bearings and may cause foreign material, such as particles from worn bearings, to be expelled out of the brush arm, contaminating the cleaning chamber. To avoid detrimental damage to the bearings and contamination of the cleaning chamber, the brush arm is typically changed relatively frequently. Frequent changing of the brush arm, however, causes extensive tool downtime, increases the chance of contaminating the cleaning chambers and increases tool operation and maintenance costs.
SUMMARY OF THE INVENTION
In one aspect, the present invention is directed to a system for purging/venting a driven mechanism with a gas, wherein the driven mechanism has a first portion and a second portion spaced from the first portion. The system comprises a support member for supporting the driven mechanism and defining a first cavity for containing the driven mechanism. The support member has a gas supply port for supplying the gas to the first cavity proximate the first portion of the driven mechanism and an evacuation port for removing the gas from the first cavity proximate the second portion of the driven mechanism. The support member is configured so that the gas does not drive the driven mechanism.
In another aspect, the present invention is directed to a method of purging/venting a driven mechanism located within a cavity of a support member, wherein the driven mechanism having a first portion and a second portion spaced from the first portion. The method comprises the steps of supplying a gas to the cavity proximate the first portion of the driven mechanism and evacuating the gas from the cavity proximate the second portion of the driven mechanism so that said gas does not drive the driven mechanism.
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Cline Scott R.
Harvey Christopher E.
Kalvaitis Willi O.
Moquin Davis H.
Downs Rachlin & Martin PLLC
Snider Theresa T.
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