AUTOMATIC TIP APPROACHING METHOD AND DEVICE FOR SCANNING TYPE PROBE MICROSCOPE

摘要

PURPOSE: To realize noncontact positioning of a detection probe without requiring any operational mark by lowering an oscillatory cantilever down to an acoustic coupling region and then transferring the cantilever to an interatomic interaction region. CONSTITUTION: An oscillatory cantilever 18 is lowered from a first position down to an acoustic coupling region where the oscillation amplitude of the lever 18 is attenuated as a result of acoustic coupling. When a detection probe 12 approaches a target surface 20, interaction between an atom at the end part of a chip 19 and an atom on the surface 20 produces a component of force having highest effect and the oscillatory amplitude of the lever 18 is varied significantly. An exciting signal is increased during the approach and the chip 19 tries to oscillate with a large amplitude. But an approach actuator 14 tries to bring the probe 12 close to the surface 20 and an analog servo circuit 15 tries to separate the probe 12 therefrom thus increasing the gap between the chip 19 and the surface 20. The exciting signal is then alternated to increase the oscillation amplitude of the lever 18 and the gradient is measured at each incremental ratio. The approach is repeated until a predetermined gradient is obtained and the chip 19 arrives at an optimized scanning distance.