Automatic wafer loading and pre-alignment system

• US 3,902,615 A
• Filed: 03/12/1973
• Issued: 09/02/1975
• Est. Priority Date: 03/12/1973
• Status: Expired due to Term

• Current Assignee: Prime Computer, Inc. (DR Holdings, Inc. of Delaware)
• Original Assignee: Alan J. Fleming, David Corbin, David Friedman, Gerd Schliemann, Gilbert G. Fryklund, Kenneth Levy, Vance Parker
• Inventors: Friedman, David, Levy, Kenneth, Corbin, David, Fleming, Alan J., Fryklund, Gilbert G., Parker, Vance, Schliemann, Gerd
• Primary Examiner(s): Spar, Robert J.
• Assistant Examiner(s): Johnson, R. B.
• Application Number:
  US05/340,281
• Time in Patent Office: 904 Days
• Field of Search: 214/16.4R,301,309,6.2,1R,1Q,1BC 318/640 250/201
• US Class Current: 414/331.17
• CPC Class Codes: B65H 2301/42256 Pallets; Skids; Platforms with feet, i.e. handled together with the stack
• CPC Class Codes: H01L 21/67259 Position monitoring, e.g. misposition detection or presence detection
• CPC Class Codes: H01L 21/67766 Mechanical parts of transfer devices robots in general in B25J
• CPC Class Codes: H01L 21/67778 involving loading and unloading of wafers
• CPC Class Codes: H01L 21/681 using optical controlling means
• CPC Class Codes: Y10S 414/135 Associated with semiconductor wafer handling
• CPC Class Codes: Y10S 414/136 including wafer orienting means
• CPC Class Codes: Y10S 414/137 including means for charging or discharging wafer cassette

Abstract

An automatic wafer loading and pre-alignment system for integrated circuit wafer-mask Aligners. A belt feed track system is employed to transport wafers from a '"'"''"'"''"'"''"'"'send'"'"''"'"''"'"''"'"' wafer storage carrier to a wafer pre-alignment station. The wafer is mechanically pre-aligned with respect to the wafer chuck of the Aligner by means of a roller arm and flat-finder system. After completion of the pre-alignment process, the Aligner turntable is rotated to carry the pre-aligned wafer and chuck to the home position of the turntable and at the same time position another chuck at the pre-alignment station. If the new chuck at the prealignment station contains a wafer, the wafer is transported from the chuck to a '"'"''"'"''"'"''"'"'receive'"'"''"'"''"'"''"'"' wafer storage carrier by means of a belt return track system. The feed and return wafer belt track systems have a common portion between the pre-alignment station and the respective send and receive wafer storage carriers. Photosensors are used to detect the presence or absence of wafers at critical locations in the loading system and at the prealignment station.

Claims

1. A wafer loading system for integrated circuit mask aligners which have a loading station for loading and unloading unexposed and exposed wafers, respectively, said wafer loading system comprising:

a send wafer carrier means for storing a plurality of unexposed wafers and a receive wafer carrier means for storing a plurality of exposed wafers, said send and receive wafer carriers each comprising a vertically movable tray having a plurality of paired, horizontal slots adapted to receive and horizontally hold in superposed relation said unexposed and exposed wafers;

vertically movable means for supporting said send wafer tray;

means for vertically moving said send wafer tray supporting means and said receive wafer tray supporting means in synchronization;

a return wafer belt transport means running between said loading station and said receive wafer carrier means;

a feed wafer belt transport means running from said send wafer carrier means to said return wafer belt transport means for removing said unexposed wafers from said send wafer carrier means, transporting the unexposed wafers to said return wafer belt transport means and depositing said wafers thereon;

means for driving said feed wafer belt transport means in a feed wafer direction; and

, means for driving said return wafer belt transport means in a feed wafer direction to transport the unexposed wafers deposited thereon to said loading station and in a return wafer direction to transport the exposed wafers from said loading station to said receive wafer carrier means.

2. The wafer loading system of claim 1 wherein at least a portion of said feed wafer belt transport means is substantially normal to said return wafer belt transport means.

3. The wafer loading system of claim 1 wherein said send and receive wafer tray supporting means are moved vertically in synchronization by equal amounts, but in opposite directions.

4. The wafer loading system of claim 3 wherein said send wafer tray supporting means moves downwardly while said receive wafer tray moves upwardly.

5. The wafer loading system of claim 3 wherein said feed and return wafer belt transport means transport said unexposed and exposed wafers in a horizontal plane and wherein a portion of said feed wafer belt transport means extends into said send wafer tray and a portion of said return wafer belt transport means extends into said receive wafer tray.

6. The wafer loading system of claim 5 further characterized by photosensor means for detecting the presence of a wafer in said receive wafer tray when the wafer is on the portion Of the return wafer belt transport means within said receive wafer tray.

7. The wafer loading system of claim 6 wherein said photosensor means comprises:

means for generating a beam of light which intersects the horizontal extension of said return wafer belt transport means portion within said receive wafer tray at an acute angle; and

, light beam responsive means positioned to intercept said light beam after it intersects said horizontal extension.

8. The wafer loading system of claim 7 further characterized by photosensor means for detecting the presence of a wafer in said send wafer tray when the wafer is on the portion of the feed wafer belt transport means within said send wafer tray.

9. The wafer loading system of claim 8 wherein said photosensor means comprises:

means for generating a beam of light which intersects the horizontal extension of said feed wafer belt transport means portion within said send wafer tray at an acute angle; and

light beam responsive means positioned to intercept said light beam after it intersects said horizontal extension.

10. A wafer loading system for integrated circuit mask aligners which have a loading station for loading and unloading unexposed and exposed wafers, respectively, said wafer loading system comprising:

a send wafer carrier means for storing a plurality of unexposed wafers and a receive wafer carrier means for storing a plurality of exposed wafers, and said send and receive wafer carriers each comprising a vertically movable tray having a plurality of paired, horizontal slots adapted to receive and horizontally hold in superposed relation said unexposed and exposed wafers;

a support platform for said send wafer tray;

a support platform for said receive wafer tray;

mounting means for said send wafer tray platform which permits only vertical movement of the platform;

mounting means for said receive wafer tray platform which permits only vertical movement of the platform;

pivotally mounted rocker lever means for linking said platforms together to allow the platforms to move in opposite vertical directions;

lead screw means mechanically coupled to one of said tray supporting platforms whereby rotation of said lead screw means will raise and lower said one platform while the other platform moves vertically in the opposite direction;

means for rotating said lead screw means;

a return wafer belt transport means running between said loading station and said receive wafer carrier means;

a feed wafer belt transport means running from said send wafer carrier means to said return wafer belt transport means for removing said unexposed wafers from said send wafer carrier means, transporting the unexposed wafers to said return wafer belt transport means and depositing said wafers thereon;

means for driving said feed wafer belt transport means in a feed wafer direction; and

means for driving said return wafer belt transport means in a feed wafer direction to transport the unexposed wafers deposited thereon to said loading station and in a return wafer direction to transport the exposed wafers from said loading station to said receive wafer carrier means.

11. The wafer loading system of claim 10 wherein said means for rotating said lead screw means comprises:

a Geneva drive means having an input and an output;

drive motor means mechanically coupled to the input of said Geneva drive means; and

, means for mechanically coupling the output of said Geneva drive means to said lead screw means.