| 摘要 |
PURPOSE:To prevent the reverse side of a wafer from being damaged and from being contaminated by a method wherein, when the wafer is lifted up, a wafer retention part is first lifted up to the rear of the wafer and is stopped and then, after the wafer has been retained by vacuum suction, the wafer is lifted up. CONSTITUTION:When a wafer 6 is transported to the upper part of a wafer retention part 1 by using a transfer belt 7, an ultrasonic pulse. is sent from an ultrasonic generator 31, and a reflected wave which has hit the rear of the wafer 6 is received by an ultrasonic receiver 32. This wave is converted into a distance by an arithmetic circuit; a converted value is supplied to a motor drive pulse generation circuit, and a drive pulse to a pulse motor is generated. The wafer retention part 1 is lifted up by the distance which has been measured via a coupling rod 4; the surface of the wafer retention part 1 comes into contact with the reverse side of the wafer 6. Then, the wafer retention part 1 sucks the wafer 6 by a vacuum and retains it. The wafer retention part 1 is further lifted up and release the wafer 6 from the transfer belt 7. |
