Apparatus for conveying a semiconductor wafer

Claim 1

A transfer apparatus (14) for conveying a semiconductor wafer (90) between a first location (42) at a first pressure and a second location (12) at a second pressure without substantially affecting the pressure at either location (42, 12) characterized by: a substantially airtight transfer chamber (26) disposed between the first and second locations (42, 12), the transfer chamber (26) including a first closeable port (38) for providing communication between the first location (42) and the transfer chamber (26), a second closeable port (40) for providing communication between the second location (12) and the transfer chamber (26) and port actuator means (46) for opening and closing the first and second ports (38, 40); transfer means (84) for transferring the wafer (90) between locations (42, 12) including first and second elongated arm members (86, 88) each having first and second ends, the first end of the first arm member (86) being pivotally supported within the transfer chamber (26) and the first end of the second arm member (88) being pivotally supported by the first arm member (86) proximate to the second end of the first arm member (86), the second end of the second arm member (88) being adapted to receive and support a semiconductor wafer (90), the first and second arm members (86, 88) being of sufficient length and being cooperative to pivot to at least three positions, the three positions including a first position in which at least a portion of the second end (92) of the second arm member (88) extends through the first port (38), a second position in which at least a portion of the second end (92) of the second arm member (88) extends through the second port (40) and an intermediate position in which both arm members (86, 88) are located within the transfer chamber (26), whereby a semiconductor wafer (90) may be placed upon the second end (92) of the second arm member (88) when the arm members (86, 88) are in one of the first or second positions and may be removed when the arm members are in the other of the first and second positions; arm member actuator means (96) for pivoting the first and second arm members (86, 88) to the first, second and intermediate positions; pressure adjusting means for adjusting the pressure within the transfer chamber (26) to either the first or the second pressure; and control means (158) for controlling the port actuator means (46), the arm member actuator means (96) and the pressure adjusting means, whereby the pressure within the transfer chamber (26) is adjusted only when both ports (38, 40) are closed with the arm members (86, 88) in the intermediate position, whereby the first port (38) is opened to permit the arm members (86, 88) to pivot to the first position only when the pressure within the transfer chamber (26) has been adjusted to the first pressure, and, whereby the second port (40) is opened to permit the arm members (86, 88) to pivot to the second position only when the pressure within the transfer chamber (26) has been adjusted to the second pressure.