Electron and ion beam apparatus and passivation milling

摘要

A three element asymmetric lens system having a very low chromatic aberration coefficient is used in conjunction with a TFE electron source having an angular intensity of approximately 10-3 amperes per steradian to achieve precise focusing of the resulting electron beam despite the large energy spread thereof for beam, accelerating ratios in the range from 0.2 to 6.0. In one embodiment, an FI ion source is used in conjunction with the same type of lens system to initially visualize the surface of the integrated circuit. The ion beam then is rapidly focused on and scanned across a small area of passivation over an underlying metal conductor to sputter a hole through the passivation layer to the metal. A secondary electron collecting apparatus detects a large increase in the secondary electron emission when the ion beam reaches the metal. The electron beam then is scanned across the surface of the integrated circuit. The resulting secondary electrons are collected, amplified and input to the intensity control of a CRT, resulting in a display in which the brightness of the location of the milled hole accurately represents the voltage of the metal conductor.