| 摘要 |
<p>A scanning microprobe in which a gun generates a beam of charged particles controlled to scan the surface of a specimen in a predetermined and defined manner. In order to permit blanking of the particle beam by removing the trace of the beam from the surface of the specimen at a particular time for a predetermined period, high-speed, high-stability switching circuitry is utilized. A vertical MOSFET switching transistor is connected between one plate and ground of the system. Also connected between this plate and a deflection voltage source is R current-limiting resistor having a ratio of approximately 15 9 000-1 with respect to the switch MOSFET in its turned-on condition. A second switch is provided to momentarily shunt the currentlimiting resistor when the MOSFET switch is turned off. This produces an initial rapid rise time of voltage on the deflection plate causing the beam to immediately move off the specimen surface. Turning off of the MOSFET switch and momentarily turning on the shunting switch is accomplished by an external beam blanking signal.</p> |
