Fabrication and characterization of CoSi₂ gate MOS tunnel structure

Fabrication processes and electrical characteristics of CoSi₂ gate MOS tunnel structures haye been studied. Thin CoSi₂ layers were grown on thin SiU₂ films by molecular beam deposition (MBD). Co and Si were simultaneously deposited with a deposition ratio of Co : Si = 1 : 2. The structural and electrical properties of the CoSi₂ layers were investigated by X-ray diffraction and Van der Pauw methods. The CoSi₂ phase was observed for samples deposited at a temperature between room temperature and 400°C. The resistivity of the layers deposited at 400°C was close to the value of CoSi₂ and did not depend on the thickness of the layers between 140 and 440Å. I-V characteristics for the CoSi₂-SiO₂-Si MOS structures were also investigated. For samples deposited under 200°C, the leak current was very larger, and Fowler-Nordheim tunnel current was not observed. On the other hand, for samples deposited above 300°C, Fowler-Nordheim tunnel current was observed. The values of the barrier height for the tunneling were estimated as 2.8 eV and 3.0 eV for samples deposited at 300°C and 400°C, respectively.