Device photolithography: The primary pattern generator part ii-mechanical design

I. INTRODUCTION The primary pattern generator (PPG) is an electromechanical light-scanning system with an unusual combination of speed and accuracy. A 10-μm-diameter light spot can be addressed successively to any or all points of a 26,000-wide by 32,000-long rectangular point array with 7-μm vertical and horizontal spacing in about ten minutes. This corresponds to a scanning rate of one spot per 600 nanoseconds. The light spot is placed repeatedly to an accuracy of about a ±7-μm total accumulated error over the whole array, and the vertical and horizontal spacing between points is maintained within ±1 μm.