Automatic cleaning apparatus for wafers

Abstract

An automatic cleaning apparatus cleans wafers one at a time without the necessity for transporting the wafers in a carrier such as a wafer cassette or basket. After a manufacturing step such as a polishing step, the wafers are carried to a loader assembly in a horizontal orientation under the influence of flowing liquid. The wafers are then individually erected into a vertical orientation by being first stopped by stopper pins which stand vertically on a wafer receiving plate of a suction arm including a suction nozzle which firmly holds the wafers while the arm is pivotally rotated until the wafer is positioned into a vertical orientation. The vertical orientation thus achieved allows the wafer to be gripped by a wafer gripping portion of a transportation robot including grooved gripping arms operated by a mechanism which limits the force applied to the wafer. Cleaning baths include an arrangement for supporting wafers in a near vertical orientation and nozzles which direct cleaning liquids in a direction tending to prevent floating of the wafers. A brush cleaning bath provides for simultaneous cleaning of both sides of the wafer with rotatory brushes, during which the wafer is supported vertically and made to move circumferentially by rollers while periodic vertical motion between the wafer-supporting rollers and the brushes is achieved with a drive motor and ball screw. A drying bath using infrared light completes the cleaning procedure before the wafers are loaded into an unloader assembly into which wafer cassettes are set.