Development of a fast beam-blanking system

摘要

In order to obtain a precise dose control for proximity effect correction, a fast beam blanking system has been developed which can make possible the fine control of the beam pulse width with precision of less than 1 nanosecond. The system consists of a high precision blanker driving circuit and a blanking structure suitable for fast operation. The blanker driving circuit controls the pulse width by selecting delay line logic with required delay. The pulse width control of less than 1 nanosecond and pulse rising time of less than 10 nanoseconds were achieved. A coaxial structure was adopted for the blanking structure. The simulation study has shown that a blanking structure with low reflectance in a few GHz range is achievable. The pulse passed through an experimental blanking structure without distortion in waveform.