A reduction camera for exposure of microcircuitry onto wafers

Considerable improvement in yield may be expected from projection exposure of wafers, since the mask defects may be virtually eliminated and some of the diffraction problems associated with contact printing minimized. The described system, developed over the past two years, consists of a 1000-W Hg arc with a 4047Å concentric interference filter, 360 mm in diameter 4 element condenser of 0.80NA with one aspheric, a diffraction limited F/3.0 lens working at 10 times reduction, covering 32 mm dia field and a wafer alignment station.