Mobility degradation in high-k transistors: the role of the charge scattering

Monte Carlo study of remote Coulomb and remote surface roughness scattering in nanoscale Ge PMOSFETs with ultrathin high-κ dielectrics

“…Neglecting the depletion charge in strong inversion and using (5b) in (5a) we get the expression for b as given in (5). The parameter a 1 should theoretically be 1/3 but we find that a value of 0.3 (as shown in Table 1) better fits the mobility versus effective field curve.…”

“…The parameter a 1 should theoretically be 1/3 but we find that a value of 0.3 (as shown in Table 1) better fits the mobility versus effective field curve. Remote Coulomb scattering has been implemented along the lines of [5]. Under the assumptions that intervalley and intersubband scattering are negligible, only the first subband is occupied and impurities are distributed only in the dielectric with no concentration variation along the lateral direction, the remote Coulomb scattering rate is given by,…”

“…In particular, in the pioneering work in [1] it was shown that the remote surface roughness limited mobility decreases with decrease in the dielectric thickness (t ox ), and the technique in [1] was used in [2] to explain the experimentally observed hole mobility reduction with decrease in t ox in Al 2 O 3 on Si transistors. In another work [5] a model of remote Coulomb scattering capable of predicting the effects of an arbitrary charge distribution in the gate dielectric was proposed and tested on experimental data on electron mobility in HfO 2 -on-Si transistors. The influence on the channel mobility of electrons of remote charge scattering from depletion charge in the polycrystalline Si gate was examined in [6][7][8][9].…”

“…Recently several experimental and theoretical studies have been performed to understand the nature and strength of the mobility degrading mechanisms in thin dielectrics (with or without high-j) on Si and Ge N-and PMOSFETs [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. In particular, in the pioneering work in [1] it was shown that the remote surface roughness limited mobility decreases with decrease in the dielectric thickness (t ox ), and the technique in [1] was used in [2] to explain the experimentally observed hole mobility reduction with decrease in t ox in Al 2 O 3 on Si transistors.…”

Statistical characterization and reliability modeling of novel high-K gate dielectric stacks

“…The major drawback when shifting to HK technology is the reduction in carrier mobility (µ) ( Fig. 2.4) that is observed due to the high density of trapped charges that cause coulomb scattering [88] of the channel carriers thereby impeding their drift and the remote soft phonon scattering [89,90] associated with the highly polarizable metaloxygen bonds in the high-κ structure. However, this reduction in µ is more than compensated by an increase in the I d .…”