| Summary: | 碩士 === 國立清華大學 === 材料科學工程學系 === 97 === Hafnium oxide is a high-k dielectric material which have dielectric constant of 25,high-k dielectric material use to be a gate oxide can decrease the threshold voltage and device scale for low voltage and microelectronics. Organic thin film transistors has been used to fabricate soft electronics devices. The active layers for OTFTs is numerous, pentacene for our research is one of most used OTFTs active layers.
In this thesis, we fabricate the HfO2 and HfON thin film by RF Reactive Magnetron Sputter System. The target is Hf metal for 99.99%, and we use Mass Flow Controller to put the Ar-O2-N2 mix gas in the chamber.HfO2 or HfON thin film would deposit on the substrate by Hf sputtering atoms react for O2 and N2.We deposit different recipes film to research their properties. Before depositing the dielectric film, we pre-deposit a Hf thin film. The thin film can decrease roughness for dielectric film, surface roughness decrease from Ra=1.972nm without Hf pre-sputtered to Ra=1.414nm with Hf pre-sputtered, this fabrication increase the device characteristics ,mobility increase from 0.086 cm2/V．s to 0.174 cm2/V．s, threshold voltage decrease from -0.7V to -0.31V,on-off ratio increase from 0.9x103 to 3.2x103, subthreshold swing decrease from -0.368 V/dec to -0.209 V/dec.
In our research, a low surface energy dielectric film would have better device characteristics of pentacene based OTFTs. In this thesis, we deposit HfON thin film by Reactive Magnetron Sputter System, and make a OTFT device which have a better characteristics.
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