Handling: hand and hoist-line implements – Contact lens applicator
Reexamination Certificate
2001-10-03
2003-10-21
Kramer, Dean J. (Department: 3652)
Handling: hand and hoist-line implements
Contact lens applicator
C294S902000, C414S941000
Reexamination Certificate
active
06634686
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
Embodiments of the invention relate to an end effector assembly for supporting substrates.
2. Background of the Related Art
Thin film transistors (TFTS) are conventionally made on large glass substrates or plates for use in monitors, flat panel displays, solar cells, personal digital assistants (PDAs), cell phones and the like. TFTs are made in a cluster tool by sequential deposition of various films including amorphous silicon, doped and undoped silicon oxides, silicon nitride and the like in vacuum chambers typically disposed around a central transfer chamber. Production of good quality polysilicon precursor films utilized in these structures requires that the hydrogen content of the film be controlled below about 1 percent. In order to achieve this low hydrogen content, post deposition heat treatment of the film at temperatures of about 550 degrees Celsius is required.
Accordingly, robots utilized to move substrates in these cluster tools must have end effectors designed to withstand these high temperatures. Generally, conventional transfer robots are not suited for operation at such high temperatures. Particularly, the end effectors of vacuum robots utilized in flat panel processing systems typically include one or more rubber friction pads upon which the substrates rest. The friction pads generally prevent the substrate from sliding relative to the end effector as the robot transfers the substrate from chamber to chamber. Several high temperature rubber compounds are available but are typically limited to a maximum operating temperature of about 320 degrees Celsius, significantly lower than the 550 degrees Celsius desired in polysilicon heat treating processes. When the end effector of the robot is exposed to high temperature for more than ten seconds, these conventional rubber pads typically melt and stick to the substrate. The melted rubber stuck to the backside of the substrate is undesirable both due to potential contamination and subsequent processing issues. Moreover, once the rubber pad is removed from the end effector, scratching of the backside of the substrate by the end effector may occur which may lead to particulate generation and substrate damage or breakage. Furthermore, if the rubber pad melts, replacement of the pad is difficult.
Therefore, there is a need for an end effector suitable for use at elevated temperatures.
SUMMARY OF THE INVENTION
In one aspect of the invention, an end effector assembly for a substrate transfer robot is provided. In one embodiment, an end effector assembly for a substrate transfer robot includes an end effector having a plurality of metallic pads disposed thereon. A polymer pad is disposed on each metallic pad wherein a ratio of an exposed portion of an upper surface of the metallic pad to a top surface of the polymer pad is at least about 3.5 to 1.
In another embodiment, an end effector assembly for a substrate transfer robot includes an end effector having a plurality of polymer pads disposed thereon is provided. Each polymer pad includes a fluoropolymer coating disposed on at least a top surface of the polymer pad.
In another embodiment, an end effector having a plurality of metallic pads disposed thereon is provided. A polymer pad is disposed on each metallic pad wherein a ratio of an exposed portion of an upper surface of the metallic pad to a top surface of the polymer pad is at least about 3.5 to 1. Each polymer pad includes a fluoropolymer coating disposed on at least a top surface of the polymer pad. The metallic pad and/or the coating allows the polymer pad to be at least temporarily utilized in applications above its normal operating temperature.
In yet another embodiment end effector assembly for a substrate transfer robot includes an end effector having a plurality of polymer pads disposed thereon is provided. The polymer pads have a patterned surface to minimize thermal transfer with the substrate.
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Applied Materials Inc.
Kramer Dean J.
Moser Patterson & Sheridan LLP
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