Role of point defects and HfO2/TiN interface stoichiometry on effective work function modulation in ultra-scaled complementary metal–oxide–semiconductor devices

Abstract

We investigate the physical properties of a portion of the gate stack of an ultra-scaled complementary metal-oxide-semiconductor (CMOS) device. The effects of point defects, such as oxygen vacancy, oxygen, and aluminum interstitials at the HfO2/TiN interface, on the effective work function of TiN are explored using density functional theory. We compute the diffusion barriers of such point defects in the bulk TiN and across the HfO2/TiN interface. Diffusion of these point defects across the HfO2/TiN interface occurs during the device integration process. This results in variation of the effective work function and hence in the threshold voltage variation in the devices. Further, we simulate the effects of varying the HfO2/TiN interface stoichiometry on the effective work function modulation in these extremely-scaled CMOS devices. Our results show that the interface rich in nitrogen gives higher effective work function, whereas the interface rich in titanium gives lower effective work function, compared to a stoichiometric HfO2/TiN interface. This theoretical prediction is confirmed by the experiment, demonstrating over 700 meV modulation in the effective work function.

Efficient binary and QAM optical modulation in ultra-compact MZI structures utilizing indium-tin-oxide

“…The material properties of ITO, TiN, and HfO2 used in these simulations are extracted from [32][33][34][35][36][37][38][39][40][41][42] .…”

Effects of graphene intercalation on dielectric reliability of HfO2 and modulation of effective work function for Ni/Gr/c-HfO2 interfaces: first-principles study

“…Therefore, improving dielectric properties of thin gate dielectric and effective tuning work function are essential for reliable integration of MOS devices. Yet, as well known, proper tuning the EWF is still difficult because of its extreme sensitivity to many interfacial factors 7 , 8 . It has been reported that processing conditions of device may strongly affect the EWF 9 , 10 .…”

Impact of composition and crystallization behavior of atomic layer deposited strontium titanate films on the resistive switching of Pt/STO/TiN devices

“…Although welldefined data for ALD STO/metal interfaces are not available from the literature, the ALD HfO 2 /metal system might serve as a reference here. For these interfaces, effective metal work functions of 5.15 eV for Pt 48 and (4.56 6 0.35) eV for TiN 49 in contact to ALD HfO 2 have been determined revealing a barrier offset of roughly 0.5 eV. From the 50% values of the CDF functions (Fig.…”