Apparatus for sensing and controlling tipping movement of a semiconductor boat

摘要

A guard fence is mounted on a transfer arm used to transport a boat carrying semiconductor wafers. The fence limits tipping movement of the boat and includes a plurality of sensors to sense tipping movement of both the top and bottom of the boat, in opposite tipping directions. A guard cover includes sensors that sense when the boat is tipped off-axis before the boat is moved into a process chamber by a boat elevator. Each of the sensors delivers signals to a controller which controls the operation of the transfer and elevator and interrupts operation thereof when the boat has tipped off-axis.