Material or article handling – Apparatus for moving material between zones having different...
Reexamination Certificate
1997-06-17
2001-08-28
Bratlie, Steven A. (Department: 3652)
Material or article handling
Apparatus for moving material between zones having different...
C414S937000, C414S940000, C414S805000
Reexamination Certificate
active
06280134
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to semiconductor wafer fabrication systems, and to an improved apparatus and method for transferring semiconductor wafers and semiconductor wafer carriers within a given semiconductor wafer fabrication tool, or within a collection of semiconductor wafer fabrication tools.
BACKGROUND
The semiconductor industry continuously searches for ways to reduce the cost per wafer processed. Several factors that affect processing costs are the costs associated with maintaining a clean room environment; equipment costs, including high precision wafer handling equipment; labor costs and the cost associated with non-value added time such as the time required for wafer transport between process chambers. Wafer costs can be reduced significantly by reducing the footprint of equipment requiring a clean room environment and by reducing the need for expensive multi-axis wafer handlers. Further reductions in wafer cost are achieved by reducing the time required to transfer wafers between a wafer carrier and a process chamber. Therefore the semiconductor fabrication industry continuously seeks improved fabrication tool configurations so as to reduce the fabrication tool's footprint, and so as to reduce the cost of fabrication tool components by simplifying the wafer transfer process.
Accordingly a need exists for a method and apparatus that, in a reduced footprint configuration, speeds and simplifies wafer transfer both within a given fabrication tool and within a collection of fabrication tools.
SUMMARY OF THE PREFERRED EMBODIMENTS
The present invention provides an improved apparatus and method for transferring wafer carriers between processing locations, and for extracting wafers from the wafer carrier and transferring them to individual process chambers. The inventive apparatus comprises an improved interface between a conveyor and one or more process chambers. In a preferred embodiment the interface comprises a chamber having two portions; the first portion being configured such that a conveyor may extend therethrough and the second portion being configured such that a first wafer carrier positioned on an elevator within the second portion may index between a first position and a second position without obstructing the passage of a second wafer carrier traveling through the first portion. Alternatively, if each wafer carrier is required to stop at each interface, the second portion may be configured without regard for the unobstructed passage of wafer carriers through the first portion. The second portion of the chamber has at least one window for connecting at least one process chamber.
Preferably, the first and second positions are top and bottom positions, such that when the interface connects a single process chamber, the top position will allow a wafer handler associated with the process chamber to extract the bottom wafer from the wafer carrier and transfer it to the process chamber via the first window; and the bottom position will allow the wafer handler to extract the top wafer from the wafer carrier and transfer it to the process chamber via the first window. The first wafer carrier may index to a plurality of positions between the top and bottom positions, allowing each wafer within the wafer carrier to be extracted via the first window. Similarly, when the interface connects more than one process chamber, the top position will align the bottom wafer with the window having the highest elevation and the bottom position will align the top wafer with the window having the lowest elevation.
The process chamber is positioned relative to the interface such that the wafer handler associated with the process chamber travels in a straight line (i.e., exhibits single axis movement) between the interface and the process chamber. In this manner, the present invention advantageously replaces the multi-axis movement required of prior art wafer handlers and the greater expense and larger footprint associated therewith. Within the present invention each wafer transfer mechanism (e.g., the conveyor, the elevator and the wafer handlers) performs only single axis movement. Further, in the present invention, the wafer handlers travel a much shorter distance than do the wafer handlers of prior art systems. Thus, the transportation system of the present invention is also more reliable than prior art systems.
Unlike conventional wafer handlers, the present invention utilizes a single indexer to perform several functions: removing a wafer carrier from the conveyor, transporting the wafer carrier to a position for process chamber loading, and indexing the wafer carrier to transfer individual wafers to the wafer handler for individual wafer movements. Thus, the present invention provides a simpler, lower-cost mechanism for performing several necessary wafer transfer functions.
In one aspect, the interface of the present invention has a plurality of ports and thus allows a plurality of wafer handlers to access wafers at any given time. The inventive Interface therefore reduces wafer transfer time and facilitates wafer handoff between a pair of process chambers which require similar atmospheres.
In a further aspect, the inventive interface comprises a conventional pod opening mechanism within the elevator chamber which causes the cover of a pod-type wafer carrier to remain above as the base plate of the a pod type wafer carrier and the cassette mounted thereon descend within the second portion of the elevator chamber. In this manner the pod-type wafer carrier may be simply and efficiently opened as the wafer carrier moves into position for wafer extraction.
The inventive interface connects a number of process chambers to provide wafer/wafer carrier transport within an inventive fabrication tool. Further, in an aspect where the inventive interface connects a first conveyor to a conveyor positioned at a distant elevation, the interface of the present invention provides a method and apparatus for factory-wide automated semiconductor processing.
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Applied Materials Inc.
Bratlie Steven A.
Dugan & Dugan LLP
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