Micromachining of pulsed laser annealed PECVD SixGe1-x deposited at temperatures ≤ 370°C

This work studies the possibility to treat plasma enhanced chemical vapor deposited (PECVD) silicon germanium (Si_xGe_1-x) thin films grown at 370°C or lower with a pulsed excimer laser for obtaining good MEMS structural layers. The main advantage of using PECVD is that a high growth rate (∼ 35 nm/min) can be achieved at low temperatures (≤ 370°C). It is demonstrated that optimizing the pulse fluence, number and rate yields high quality films characterized by a low defect density (∼ 102 defect/cm²), large grains (∼ 300 nm), a low mean stress (∼ 40 MPa) and a low stress gradient.