Study On The Ge MOS Capacitance With High-K Dielectric And It’s Preparation

With the integration of IC increasing, the device has entered the nano-scale size andthis trend is still shrinking, and use conventional Si/SiO2/polysilicon structure will leadthe tunneling current increases rapidly because of the ultra-thin SiO2gate, cause thefunction of MOSFET failure. Use the High-K dielectric material instead of thetraditional SiO2, MOS structure can keep the whole performance while maintain a thickgate oxide layer, this restrain the increase of tunneling current. But using High-Kdielectric will bring two significant problems: one is the Si/High-K interface statedensity is not good, the other is that the High-K dielectric is not compatible with thepolysilicon, it’s increase the threshold voltage and decay the carrier mobility. Therefore,the Ge substrate and metal needed to replace the Si substrate and polysilicon gate, thisGe/High-K/metal gate electrode structure solve the problems above and become anexcellent potion for the next-generation semiconductor devices.This paper mainly studies the interface characteristics of the Ge/High-K/metal gateelectrode structure and some methods to improve it, including NH3surface passivation,ultra-thin Si surface passivation, F processing, stacking layer structure, PDA and PMA.And put forward to a generally inference about improve the Ge substrate/High-Kinterface characteristics, provide theory basis for the subsequent research. In the end,preparation the Ge-MOS capacitor using HfO₂, Al₂O₃, Nd₂O₃as the gate dielectric andmeasure the C-V curves. Analysis relevant electrical parameters, provide theexperimental data for future production.The results of this paper show that, grow the High-K dielectric films on the Gesubstrate directly without processing interface, will exist large Ditin the interface.Reflect in the measured C-V characteristic curve for the serious lag. In addition,according to the experimental data, the thickness of Al₂O₃and Nd₂O₃film is smallerthan expected, indicate the growth rate of the two materials is lower than the theoreticalvalue. Analyze the reasons for the source temperature is not enough, suggestion thatelevate the source temperature or increase cycles. And the thickness of HfO₂film nearthe expectations, indicate the parameter setting of ALD system for HfO₂film grow isbetter. Finally, compare the10nm Al₂O₃film Ge-MOS capacitance with15nm. Foundthat the thickness of gate is inversely to capacitance, follow the generally rule.