Two further potential extrinsic causes: polysilicon depletion effect [58–60] and quantum mechanical confinement [61–63], for frequency dispersion were negligible if the thickness of the high-k thin film is high enough. Polysilicon depletion effects were not considered due to the implementation of metal gate. Existing causes of extrinsic frequency dispersion during C-V measurement in the high-k thin film were the parasitic
effect (including back contact imperfection resistance R S ’ and capacitance C S ” , cables resistance R S ” and capacitance C S ” , substrate series resistance R S , and depletion layer capacitance of silicon C D ) and the lossy interfacial layer effect (interfacial layer capacitance BAY 57-1293 C i and conductance G i ). Surface roughness effect and polysilicon
depletion effect were included, where high-k capacitance C h , high-k conductance G h , the lossy interfacial layer capacitance C i and conductance www.selleckchem.com/products/BMS-777607.html G i were given. The oxide capacitance C ox consisted of the high-k capacitance C h and the lossy interfacial layer capacitance C i . Figure 1 Causes of frequency dispersion during C-V measurement in the MOS capacitor with high- k dielectric [[56]]. Parasitic effects in MOS devices included parasitic resistances and capacitances such as bulk series resistances, series contact, cables, and many other parasitic effects [64–67]. However, learn more only two of them which had influential importance are listed as follows: (1) the series resistance R S of the quasi-neutral silicon bulk between the back
contact and the depletion layer edge at the silicon surface underneath the gate; and (2) the imperfect contact of the back of the silicon wafer. Dispersion could be avoided by depositing an Al thin film at the back of the silicon substrate. The correction models were able to minimize the dispersion as well. Then, it has been demonstrated that once the parasitic components are taken into account, it was possible to determine the true capacitance values free from errors. The existence of frequency dispersion in the LaAlO3 sample was discussed in the previous work [68], which was mainly due to the effect of the lossy interfacial layer between the high-k thin film and silicon substrate on the MOS capacitor. The frequency dispersion effect was significant even with the Al back contact and the bigger substrate area. In this case, C h (CET = 2.7 nm) was comparable with C i (approximately 1-nm native SiO2) and the frequency dispersion effect was attributed to losses in the interfacial layer capacitance, caused by interfacial dislocation and intrinsic differences in the bonding coordination across the chemically abrupt ZrO2/SiO2 interface. Relative thicker thickness of the high-k thin film than the interfacial layer significantly prevented frequency dispersion.