|
As dimension of electric device continue to shrink, it is becoming increasingly important to understand how to obtain good quality gate oxide film materials. With higher carrier mobility, lower leakage current and excellent reliability have become major concerns to fabricate thin film oxide transistors. A novel film deposition method called Inductively Coupled Plasma -Chemical Vapor Deposition (ICP-CVD) has become more attractive in the semiconductor industry. Because it can be capable of generating high density plasmas at extremely low temperature which results in less ion bombardment of material surface. In this work, we present the results of crystallized silicon dioxide films deposited by inductively coupled plasma chemical vapor deposition technique at extremely low temperature of 90°C.The value of refractive index of crystallized ICP-CVD SiO2 film depends on the r.f. power of ICP system and approximates to be 1.46. This value is comparable to that prepared by the thermal oxidation SiO2 films. As the r.f. power of ICP is more than 1250 Watts, only the (111) diffraction peak is observed by XRD which implies a very strong preferred orientation or single crystal structure. Too low or too high r.f. power both produce amorphous SiO2 films that may be attributed to a very low deposition temperature for the former and the hydrogen etching effect for the latter. From the I-V curve, it can be seen that the MIS device with SiO2 dielectric film has lower leakage current density of 6.8×10-8A/cm2 at 1V as the film prepared at 1750 watts. The highest breakdown field in this study is 15.8 MV/cm. From the FTIR analysis, it was found that more hydrogen atoms incorporate into films and form Si-OH bonds as the r.f. power increases. The existing of Si-OH bonds lead to a poor reliability of MIS device. |