Laser projection patterning for the formation of thin film diamond microstructures

Projection patterned excimer laser radiation at 193 nn has been used to etch free-standing polycrystalline diamond films. Excellent lateral reproduction of images down to 2 lan has been achieved, but features evolve with a side wall. that slopes at around 25 degrees to the normal; this limits the depth of each feature in relation to its lateral dimension. However, three-dimensional microgears, with a diameter of 930 mu m, have been successfully fabricated using this technique. Patterning in air gives rise to etch rates as high as 31 nm per laser pulse, but in an evacuated environment this is reduced to around 0.6 nm; furthermore, Raman spectra indicate that patterning in vacuo leaves strongly modified surfaces, whilst air processing causes little degradation to the diamond film.