Direct fabrication of large-grain polycrystalline silicon thin films by RF-biased RF-PECVD at low temperature

Polycrystalline silicon (Poly-Si) films with large grains are successfully fabricated on glasses in a self-assembled RF-biased RF-PECVD tubular system. Both inductively coupled and capacitively coupled RF powers are employed. High purity (99.99%) SiH4, H2 and Ar are introduced as resource gases. All crystalline films obtained in this study exhibit (111)-Si preferred orientation. Poly-Si films with large grains (about 0.15–0.3 mm in size) which are aggregate of fine crystals (about 50 nm in size) are deposited at the deposition temperature less than 77 °C. However, the improvement of crystallinity and the grain size are still under investigation.