Method and apparatus for aligning a cassette

Abstract

An alignment tool, method and system are provided for aligning a cassette handler to a robot blade in a workpiece handling system, in which the tool comprises a frame or fixture adapted to be supported by the cassette handler support surface, in which the frame has one or more distance sensors positioned to measure the distance of a workpiece or robot blade from the sensor or a predetermined reference point or surface. In a preferred embodiment, the frame emulates a workpiece cassette and the distance sensors provide a numerical output of the distance to the workpiece. As explained in greater detail below, these distance measurements facilitate accurately leveling and aligning the cassette handler support surface relative to a workpiece supported by the robot blade such that when the frame is replaced by an actual workpiece cassette, the workpiece cassette will also be level and aligned with respect to the robot blade and the workpiece held by the blade. As a consequence, accidental scratching and breakage of workpieces such as semiconductor wafers and display substrates may be reduced or eliminated.

Description

[0001] The present invention relates to automated workpiece handling systems, and more particularly, to methods and devices for aligning a cassette for workpieces in an automated workpiece handling system.[0002] In order to decrease contamination and to enhance throughput, semiconductor processing systems often utilize one or more robots to transfer semiconductor wafers, substrates and other workpieces between a number of different vacuum chambers which perform a variety of tasks. An article entitled "Dry Etching Systems: Gearing Up for Larger Wafers", in the October, 1985 issue of Semiconductor International magazine, pages 48-60, describes a four-chamber dry etching system in which a robot housed in a pentagonal-shaped mainframe serves four plasma etching chambers and a loadlock chamber mounted on the robot housing. In order to increase throughput, it has been proposed to utilize two loadlock chambers as described in U.S. Pat. No. 5,186,718. In such a two loadlock system, both loa...

AI Technical Summary

Benefits of technology

[0011] The present inventions are, in one aspect, directed to an alignment tool, method and system for aligning a cassette handler to a robot blade in a workpiece handling system, in which the tool comprises a frame or fixture adapted to be supported by the cassette handler support surface, in which the frame has one or more distance sensors positioned to measure the distance of a workpiece or robot blade from the sensor or a predetermined reference point or surface. In a preferred embodiment, the frame emulates a workpiece cassette and the distance sensors provide a numerical output of the distance to the workpiece. As explained in greater detail below, these distance measurements facilitate accurately leveling the cassette handler support surface relative to a workpiece supported by the robot blade such that when the frame is replaced by an actual workpiece cassette, the workpiece cassette will also be level with respect to the robot blade and the workpiece held by the blade. As a consequence, accidental scratching and breakage of workpieces such as semiconductor wafers and display substrates may be reduced or eliminated.

Problems solved by technology

However, typical prior methods for aligning the handler and cassette to the robot blade have generally been relatively imprecise, often relying upon subjective visual inspections of the clearances between the various surfaces.

However, many of these tools have a number of drawbacks.

Such contact can be very detrimental to high precision mechanisms for moving the blade as well as the blade itself.

In addition to being very subjective, such bubble tools have also often been difficult to see in the close confines of the cassette and handler mechanisms.

As a consequence of these and other deficiencies of the prior alignment procedures and tools, alignments have often tended to be not only imprecise but also inconsistent from application to application.

These problems have frequently lead to the breakage or scratching of very expensive wafers and equipment as well as the generation of damaging particulates in the systems.

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