High resolution CD-SEM system

Because of rapidly decreasing line-width of integrated circuits, it is necessary to measure and control their critical dimensions with high accuracy. We have developed a new critical-dimension-measurement scanning electron microscope (CD-SEM) S-9000 series, which has a new electron optics with retarding and boosting electric fields. To optimize the boosting voltage we have developed optics simulators that are capable of computing aberration coefficients and secondary electron detection efficieny in electric and magnetic mixed fields. At the optimized boosting voltage of around 5 kV for a final accelerating voltage of 800 V, not only 3 nm resolution but also highlighted bottom imaging of high aspect ratio contact holes is obtained.