Patent ID: 6169490
Filing Date: 2001-01-02
Classification: H01L,Y10S

Abstract:
An installation for protecting an outlet port of a stocking unit, comprising: the outlet port; four wafer boat supporters for supporting a wafer boat, wherein the wafer boat supporters are separated from each other by a fixed distance and the supporters are positioned at corners of a square centered upon the outlet port; two wafer boat sensors mounted on two of the wafer boat supports positioned at opposite corners for sensing the pressure caused by a weight of a wafer boat; a first light-intercepting sensor positioned on one side of the outlet port; and a second light-intercepting sensor positioned on the other side of the outlet port; wherein when no wafer boat is in the outlet port, the first light-intercepting sensor is capable of picking up light coming in from a direction of the second light-intercepting sensor, and when a wafer boat is placed inside the outlet port, the light is blocked by the wafer boat so that the stocking unit is able to decide whether or not to forward wafer boat to the outlet port based on information provided by the wafer boat sensors and the light-intercepting sensors.