Yasuaki Murata

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 (TFTs) 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 TFTs 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/(Vs) were achieved in n-channel and p-channel TFTs, respectively, fabricated on glass substrates.

Laser-Beam Direct Writing of TiO2 Channels for Fabrication of Ti:LiNbO3 Waveguides

A novel photoresist-free process used for fabrication of Ti:LiNbO3 waveguides is proposed and demonstrated. In this process, smooth waveguide patterning of TiO2 channels can be performed by laser-beam (LB) direct writing at up to 0.2 mm/s, where Ti film deposited on LiNbO3 is thermally oxidized in air by the focused Ar+ laser beam. LB writing has sufficiently high accuracy for waveguide patterning because the Ti film thickness is usually below 0.1 µm. Unlike the previously reported resist-free processes, the process demonstrated here does not require any specific tools or materials, and can provide Ti:LiNbO3 waveguides more easily. It was also confirmed that there are no marked differences in guiding properties between two Ti:LiNbO3 waveguides fabricated by the proposed resist-free process and the standard process based on waveguide patterning in photoresist as thick as 1 µm.