Acoustic mode converters micromachined in silicon by proton beam writing

Proton beam writing is a powerful tool for the production of microstructures for acoustic applications because it allows to create structures inclined to the original sample surface which therefore can act as acoustic mode converters. We report on experiments, finding optimal structure sizes in p-type 12 Ω cm silicon for this purpose. For the creation of the structures the proton beam at the LIPSION laboratory was used. Furthermore, by investigating the micromachined silicon with a phase sensitive acoustic microscope we give evidence that inclined structures such as rods and walls can be used to change the mode of acoustic waves in the crystal.