Angle lapping of multilayer structures for thickness measurements using focused ion beam micromachining
Focused ion beam (FIB) micromachining has been carried out to angle-lap multilayer structures for layer thickness measurements. A Ga+ FIB originating from a liquid metal ion source (LMIS), operated at 10 kV, was employed throughout. The FIB was digitally rastered, pixel by pixel, in a serpentine fashion over the area of interest, and the pixel dwell time was incremented line by line. The multilayers used were Al/SiO2/Si and Al/TiW/SiO2/Si. For the conditions set up for the FIB scan routine, control in micromachining the angle of the lapped surface is of the order of 1arcsec per scan of the ion beam over the area of interest. Use of absorbed current for the purpose of end-point detection and monitoring of the angle lapping fabrication progress is demonstrated.