Fabrication of thin diamond membranes by using hot implantation and ion-cut methods

Abstract

A thin (2 mu m) and relatively large area (3 x 3mm(2)) diamond membrane was fabricated by cleaving a surface from a single crystal chemical vapor deposition (CVD) diamond wafer (3 x 3mm(2) x 300 mu m) using a hot implantation and ion-cut method. First, while maintaining the CVD diamond at 400 degrees C, a damage zone was created at a depth of 2.3 mu m underneath the surface by implanting 4MeV carbon ions into the diamond in order to promote membrane cleavage (hot implantation). According to TEM data, hot implantation reduces the thickness of the implantation damage zone by about a factor of 10 when compared to implanting carbon ions with the CVD diamond at room temperature (RT). In order to recover crystallinity, the implanted sample was then annealed at 850 degrees C. Next, 380 keV hydrogen ions were implanted into the sample to a depth of 2.3 mu m below the surface with the CVD diamond at RT. After annealing at 850 degrees C, the CVD diamond surface layer was cleaved at the damage-zone due to internal pressure from H-2 gas arising from the implanted hydrogen (ion-cut). A thin layer of graphite (similar to 300 nm) on the cleavage surface, arising from the implanted carbon, was removed by O-2 annealing. This technique can potentially be used to produce much larger area membranes of variable thickness.