High mobility high-k/Ge pMOSFETs with 1 nm EOT-new concept on interface engineering and interface characterization

Abstract

High-k/Ge interfaces are significantly improved through a new interface engineering scheme of using both effective pre-gate surface GeO 2 passivation and post gate dielectric (post-gate) treatment incorporating fluorine (F) into high-k/Ge gate stack. Minimum density of interface states (D it) of 2 x 10 11 cm -2eV -1 is obtained for Ge MOS capacitors. Hole mobility up to 396 cm 2/Vs is achieved for Ge pMOSFETs with EOT ∼10 Å and gate leakage current density less than 10 -3 A/cm 2 at V ± 1 V. Best drain current to date of 37.8 μA/|im at V g-V t = V d= -1.2V is presented for an L g of 10 μm. Variable rise and fall time charge pumping (CP) method is used to investigate Ge interface property and a significant D it reduction in both upper and lower half of bandgap is observed with F incorporation.