Patent ID: 6169935
Filing Date: 2001-01-02
Classification: H01L,Y10S

Abstract:
A stocker entry control method employed in a semiconductor wafer cassette transportation apparatus including a stocker for storing a plurality of semiconductor wafer cassettes, said stocker including a plurality of inlet ports for entry of said semiconductor wafer cassettes, a processing apparatus for applying a process on said semiconductor wafer cassettes, an automatic carrier for carrying out a transportation task of said semiconductor wafer cassettes between said stocker and said processing apparatus, an inter-stocker transport device for carrying out a transportation task of said semiconductor wafer cassettes between a source stocker and a destination stocker, and a host computer for providing control of said stocker, said inter-stocker transport device, said automatic carrier and said processing apparatus, said host computer storing data corresponding to a maximum number of cassettes that can be stored in said stocker, and said host computer storing data corresponding to a number of tasks and an upper limit value for each of said plurality of inlet ports, said stocker entry task control method comprising the steps of: confirming that there is an empty space in said stocker in which one of said semiconductor wafer cassettes is to be stored, ascertaining a storage site in said stocker when there is an empty space in said stocker, sending a transportation task instruction to said inter-stocker transport device or said automatic carrier, or an entry task instruction to said stocker, and selecting one of said plurality of inlet ports excluding the inlet port corresponding to the data having a value of said number of tasks exceeding said upper limit value.