| 摘要 |
A wafer transfer apparatus loads and unloads wafers into and from a wafer cassette. The apparatus includes an arm for picking up a wafer, a motor-driven mechanism connected to the arm for moving the arm vertically and horizontally, and a sensor for sensing when the lower surface of the arm contacts an upper surface of a wafer already seated in the wafer cassette. The sensor is made up of a sensor body, a controller, and an amplifier. The arm can be made of metal, in which case the sensor body includes an elastic layer coated on the lower surface of the arm, and an electrically conductive metal layer formed on the elastic layer. When the lower surface of the arm presses against a wafer, the metal layer contacts the metal arm and electrical signals indicative of such contact can thus be produced. Alternatively, the arm may be made of a ceramic. In this case, the sensor body includes a first electrically conductive metal layer disposed on the lower surface of the arm, an elastic layer coated on the first metal layer, and a second electrically conductive metal layer formed on the elastic layer opposite the first metal layer. When the lower surface of the arm presses against a wafer, the metal layers come into contact and electrical signals indicative of such contact can thus be produced.
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