OPTIMIZATION OF VARIABLE AXIS IMMERSION LENS FOR RESOLUTION AND NORMAL LANDING

This paper describes a variable axis immersion lens system capable of better than 0.1-mu-m resolution at 25 A/cm2 over a 10-mm2 deflection field with perpendicular landing for both electrostatic (high speed) and magnetic deflections. Computer predictions of spot acuity and landing angles are compared to actual measurements for various degrees of field compensation accuracy.