Kikuchi Y.,Semiconductor Business Group Consumer Products |
Wakabayashi H.,Semiconductor Business Group Consumer Products |
Tsukamoto M.,Semiconductor Business Group Consumer Products |
Nagashima N.,Semiconductor Business Group Consumer Products
Japanese Journal of Applied Physics | Year: 2011
For the first time, dual metal/high-k gate-last complementary metal-oxide-semiconductor field-effect transistors (CMOSFETs) with low-dielectricconstant-material offset spacers and several gate oxide thicknesses were fabricated to improve CMOSFETs characteristics. Improvements of 23aF/μm in parasitic capacitances were confirmed with a low-dielectric- constant material, and drive current improvements were also achieved with a thin gate oxide. The drive currents at 100nA/μm off leakages in n-type metal-oxide-semiconductor (NMOS) were improved from 830 to 950 μA/μm and that in p-type metal-oxide-semiconductor (PMOS) were from 405 to 450 μA/μm with a reduction in gate oxide thickness. The thin gate oxide in PMOS was thinner than that in NMOS and the gate leakage was increased. However the gate leakage did not affect the off leakage below a gate length of about 44 nm. On the basis of this result, in these gate-last CMOSFETs, it is concluded that the transistors have potential for further reduction of the equivalent oxide thickness without an increase in off leakages at short gate lengths for high off leakage CMOSFETs. For low off leakage CMOSFETs, the optimization of wet process condition is needed to prevent the reduction of the 2nm HfO2 thickness in PMOS during a wet process. © 2011 The Japan Society of Applied Physics.