Characterization of KrF excimer laser annealed PECVD SixGe1−x for MEMS post-processing

This work studies the possibility to treat plasma enhanced chemical vapor deposited (PECVD) silicon germanium (Si1−xGex) thin films grown at 400 °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 and a low stress gradient. Furthermore, the electrical resistivity of the as grown material, deposited at 210 °C, is reduced from 12 kΩ cm to 1.3 mΩ cm after laser annealing.