Exposure of PMMA with STM under ambient condition

摘要

The development of quantum electronics depends mainly on the development of nano-processing. STM has been a powerful tool for nano-processing. Before, the exposure of PMMA with STM could only be done in unltra high vacuum. The problem for exposure of PMMA under ambient condition is the unstability of the tip at tunnel condition. We used two measures to attack the problem :(1) adopted special procedure to prepare the W tip. After the formation of the tip, the tip was further etched for Is; (2) first let the system go into tunnel condition at lower voltage then raised the voltage to exposure value gradually. After these two mwasures, the tip could be stablized under ambient condition. Afterwards, we used three set of labels to approach gradually from large area to small area to locate the exposure region. Finally, we have exposed 20 nm thick of PMMA under ambient condition with STM and have obtained lines of 300 nm linewidth.