Phosphorus doping using electron cyclotron resonance plasma for large-area polycrystalline silicon thin film transistors

• Published in: Japanese Journal of Applied Physics Vol. 33; no. 1B; pp. 654 - 658
• Main Authors: KAKINUMA, H, MOHRI, M, TSURUOKA, T
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Tokyo Japanese journal of applied physics 1994
• Subjects: Applied sciences; Electronics; Exact sciences and technology; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Transistors; Plasma; Semiconductor device; Electrical properties; Doping; Polycrystal; Electron cyclotron resonance; Silicon; Thin film transistor; Experimental study
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.33.654

We have investigated phosphorus doping using an electron cyclotron resonance (ECR) plasma, for application to the poly-Si driving circuits of liquid crystal displays or image sensors. The PH 3 /He was ionized and accelerated to poly-Si and c-Si substrates with a self bias of -220 V. The P concentration, as detected by secondary ion mass spectroscopy (SIMS), is ∼5×10 21 cm -3 at the surface, which decayed to ∼10 17 cm -3 within 50–100 nm depth. The surface is found to be etched during doping. The etching is restored by adding a small amount of SiH 4 and the sheet resistance R s decreases. The optimized as-irradiated R s is ∼1×10 5 Ω/\Box and 1.7×10 2 Ω/\Box for poly-Si and (110) c-Si, respectively. The dependence of R s on the substrates and the anomalous diffusion constants derived from SIMS are also discussed.