High efficiency buffer stocker

Abstract

A high-efficiency buffer stocker is disclosed. The buffer stocker includes an overhead transport track for supporting overhead transport vehicles carrying wafer containers and at least one conveyor system or conveyor belt provided beneath the overhead transport track for receiving the wafer containers from the overhead transport vehicles on the overhead transport track. The buffer stocker is capable of absorbing the excessive flow of wafer containers between a processing tool and a stocker, for example, to facilitate the orderly and efficient flow of wafers between sequential process tools in a semiconductor fabrication facility, for example.

1 . A buffer stocker system comprising:
 an overhead transport track supporting a plurality of movable overhead transport vehicles each configured for carrying a wafer container;   a carousel positioned beneath the track and including a plurality of movable container support platforms;   wherein the carousel is operable to selectively position one of the container support platforms beneath the track for receiving a wafer container from or returning a wafer container to the overhead transport vehicle.   
     
     
         2 . The buffer stocker system of  claim 1 , wherein the container support platforms are movable around the carousel in a continuous loop shaped path. 
     
     
         3 . The buffer stocker system of  claim 2 , wherein the container support platforms are selectively movable in both a vertical direction and a horizontal direction. 
     
     
         4 . The buffer stocker system of  claim 1 , wherein the carousel comprises an enclosed conduit and the container support platforms are movable inside the conduit. 
     
     
         5 . The buffer stocker system of  claim 4 , wherein the carousel includes a container opening positioned beneath the track for receiving a wafer container into the carousel. 
     
     
         6 . The buffer stocker system of  claim 1 , wherein the carousel comprises a descending conduit, an ascending conduit, a top transverse conduit connected between the descending and ascending conduits, and a bottom transverse conduit connected between the descending and ascending conduits. 
     
     
         7 . The buffer stocker system of  claim 6 , wherein the descending and ascending conduits are spaced horizontally apart from each other. 
     
     
         8 . The buffer stocker system of  claim 7 , wherein the top and bottom transverse conduits are spaced vertically apart from each other. 
     
     
         9 . The buffer stocker system of  claim 6 , wherein the descending, ascending, top transverse, and bottom transverse conduits form a vertically-oriented continuous loop. 
     
     
         10 . The buffer stocker system of  claim 1 , further comprising a motor operable for moving the container support platforms through the carousel. 
     
     
         11 . The buffer stocker system of  claim 10 , further comprising a controller operably connected to the carousel and configured for controlling the travel direction of the container support platforms. 
     
     
         12 . A buffer stocker system comprising:
 an overhead transport track supporting a plurality of movable overhead transport vehicles each configured for carrying a wafer container;   a carousel positioned beneath the track including a descending conduit, an ascending conduit, a top transverse conduit connected between the descending and ascending conduits, and a bottom transverse conduit connected between the descending and ascending conduits; and   a plurality of container support platforms movable through the carousel;   wherein the carousel is operable to selectively position one of the container support platforms beneath the track for receiving a wafer container from or returning a wafer container to the overhead transport vehicle.   
     
     
         13 . The buffer stocker system of  claim 12 , wherein the container support platforms are movable around the carousel in an open loop shaped path. 
     
     
         14 . The buffer stocker system of  claim 12 , wherein the container support platforms are selectively movable in both a vertical direction and a horizontal direction. 
     
     
         15 . The buffer stocker system of  claim 12 , wherein the carousel includes a container opening positioned beneath the track for receiving a wafer container into the carousel. 
     
     
         16 . The buffer stocker system of  claim 15 , wherein the container opening is formed in the top transverse conduit. 
     
     
         17 . The buffer stocker system of  claim 1 , further comprising;
 a motor operable for moving the container support platforms through the carousel; and   a controller operably connected to the carousel and configured for controlling the travel direction of the container support platforms.   
     
     
         18 . A method for using a buffer stocker system comprising:
 locating a carousel beneath an overhead transport track supporting a plurality of movable overhead transport vehicles each configured for carrying a wafer container, the carousel including a plurality of open conduits and movable container support platforms;   moving a vacant first container support platform to a first position beneath the track;   receiving a wafer container onto the vacant first container support platform from one of the overhead transport vehicles; and   moving the first container support platform with wafer container around the carousel through the conduits to a second position in the carousel.   
     
     
         19 . The method of  claim 18 , wherein the first container support platform moves through a descending conduit to reach the second position. 
     
     
         20 . The method of  claim 19 , wherein the first container support platform further moves through a transverse conduit to reach the second position.