Formation of Sources/Drains Using Self-Activation Technique on Polysilicon Thin Film Transistors

Source/drain formation by ion doping using self-activation technique without thermal anneal on polysilicon thin film transistors (TFT's) have been investigated. Phosphorus ions and protons were simultaneously implanted into polysilicon films. At total ion doses over 8×1015 ions/cm2, resistivities of self-activated films have been found equal to those of the ones annealed after the implantation. This self-activation technique enabled us to fabricate self-aligned TFT's having low-resistance Al gates and, at the same time, to hydrogenate active layers. With the case of self-activation technique, field-effect mobilities as high as 58 and 49 cm2/(V·s) were achieved in n-channel and p-channel TFT's, respectively, fabricated on glass substrates.