Mask imaging photoelectronic projector - has mask as positive electrode of acceleration field between photocathode and semiconductor wafer

摘要

The photoelectronic image projector is used for forming a mask on a semiconductor wafer. It uses an electric acceleration field directed at right angles to a photocathode and the wafer. The mask (6) forms the positive electrode of the acceleration field and is mounted in spaced manner and parallel to the photocathode (3) between the same and the wafer. The mask (6) consists of a support grid and of structure increased by the grid width. The acceleration voltage and the distance of the mask from the wafer meet a specified relation, concerned with a tangential component of velocity of electrons emitted from the photocathode. Typically the mask has a positive potential of the order of 10V in relation to the wafer.