CONTROL OF APERTURE SIZE OF OPTICAL PROBES FOR SCANNING NEAR-FIELD OPTICAL MICROSCOPY USING FOCUSED ION-BEAM TECHNOLOGY

We propose a fabrication technique for apertures of optical probes for scanning near-field optical microscopy (SNOM) using a focused ion bea m (FIB) process. We tried two FIB processes: FIB drilling and FIB slic ing. The FIB slicing technique is very useful for fabrication of nm-si zed SNOM apertures of less than 50 nm. The problem with the FIB drilli ng process is that it is difficult Lo identify the apes of the tip and to control the beam onto the apex, The FIB slicing technique can easi ly fabricate an aperture at an apex and control aperture size by cut-o ff-depth. It is easy for a sharp tip to obtain accurate size of apertu re, It can be considered to obtain accurate size of aperture with fabr icated error of 35 nm in a sharp tip with cone angle of 30 deg.