金屬閘極與絕緣層上鍺 光偵測器 Metal Gate and Ge on Insulator Photodetector,指導教授：劉致為 博士 學生：李呈峻 臺灣大學電子工程學研究所,Outline,IntroductionThe Electrical Characteristics of Tantalum Nitride Metal GateGe-on-Insulator Substrates Formation by WaferBonding and Layer Transfer A Novel 850 nm, 1.3m and 1.5m GOI MOSPhotodetector for Optical Communication Summary,Problems in conventional poly silicon gate (poly-Si) High gate resistance High gate tunneling leakage current Poly silicon gate depletion Boron penetration into the channel regionSolution Metal gate,Why metal gate ?,Why tantalum metal is suitable for semiconductor industry?,Advantages Body-centered-cubic (BCC) crystal structure High melting point(2996) Low-resistance ohmic contact,Cubic, Body Centered,Cubic, Face Centered For instance, Al, Pt and Cu,Summary,Tantalum Nitride Metal Gate In experiment, we obtained that the oxide charges are positive in TEOS and the flat-band voltages concentrated -0.42V at twenty percents nitrogen flow ratio. With increasing nitrogen gas flow ratio, the thermal stability decreased by tantalum diffusion into dielectric layer. If nitrogen gas flow ratio is higher than thirteen percents, the tantalum diffusion phenomenon is obviously. Ge-on-Insulator substrates Formation The GOI surface roughness is reduced by thermal rapid annealing with hydrogen gas in furnace. The bonding condition of low temperature heat treatment is at 150 with 10% oxygen flow in furnace.,Summary,GOI MOS Photodetector The leakage current is decreased at inversion bias by platinum gate electrode. The novel GOI PMOS photodetectors have high responsivity (0.3 A/W) and high quantum efficiency of 40% at 850nm (0.25mW). The 60% enhancement is achieved with -3 dB bandwidth, comparing to bulk Ge MOS detector.,