Investigation and Localization of the SiGe Source/Drain (S/D) Strain-Induced Defects in PMOSFET With 45-nm CMOS Technology

In this letter, for the first time, the defects that are induced from the SiGe strain source/drain (S/D) in PMOSFET with 45-nm CMOS technology were investigated in detail. With the conventional charge pumping and the improved low gate-leakage gated-diode(L²–GD)measurements, we find that the uniaxial compressive stress from SiGe S/D generates a large number of acceptorlike interface states at the gate oxide/extension of S/D interface, thus enhancing the leakage current. Compared to defects that are caused by the relaxedSi₁₋ₓGeₓon the conventional gradedSi₁₋ₓGeₓbuffer layer, the SiGe S/D experienced results that are more serious. The acceptorlike interface states are suspected to be the Si dangling bonds broken by the stress. A schematic model is proposed to illustrate the effect of the stress comprehensively.