Physical parameters of the quantum mechanical interference method for the determination of oxide thickness in MOS devices

摘要

The quantum mechanical interference method to extract oxide thickness is examined in detail by fully using the least square fit fechnique. The current density. J_0, that corresponds to oscillatory peaks of n = 1. 2. 3 and 4 is plotted against n, and by doing so. data scattering among the devices is clearly recognized. The extracted physical parameters, Φ_M and m_2, have large standard deviation around the average depending on device and polarity conditions. Despite the scat- tering, an apparent success of the quantum interference (QI) analysis is obtained when the averaged parameters. Φ_M =2.94 cV and m_2/m_0 = 0.54. are used. It is discussed that both Φ_M and m_2 are equally Critical to the accuracy of the QI method. and they luckily deviate in the opposite direction around the average to cancel with each other. An essential limitation of the QI method is that the device characteristics depend on the factor (t_ox√Φ_M) and we cannot decide Φ_M and t_ox separately. T_ox to extract Φ_M and m_2 must be evaluated by the help of other technique like ellipsometry or C-V measurements.