Abstract: A method and apparatus for applying vacuum forces to at least portions of the underside of wafer handling tape to facilitate removal of sawn or scribed circuit chips from the tape, the invention includes heating of the tape/chip to further reduce adhesion of the chip to the tape. The invention reduces handling damage to circuit chips conventionally caused by manual techniques used to remove chips from handling tape and allows chip removal without the use of a conventional die ejector. Apparatus according to the invention includes a vacuum plate grooved to provide a pattern of pins having planar mounting surfaces on which the handling tape is carried, vacuum applied through the plate causing portions of the tape to pull into the grooves adjacent the pins to reduce the area of contact between the undeside of the chips and the surface of the tape on which the chips are adhered. Heating of the tape and chips while under vacuum facilitates chip removal from the tape.

Abstract: A focusing apparatus for use in a step and repeat photo-exposure system is provided in which air jets are located immediately adjacent the exposure area of the exposure system. Back pressure of the air jets is sensed to determine the distance of the optical unit of the photo-exposure system to the surface of a semiconductor wafer being exposed. The average back-pressure is utilized to control movement of the optical system in order to achieve precise focusing. A map of the surface aberration of the wafer may be obtained by measuring the position of the camera at each die site after focusing has been achieved.