Contributions to the effective work function of platinum on hafnium dioxide

Abstract

The intrinsic and extrinsic contributions to Fermi level pinning of platinum (Pt) electrodes on hafnium dioxide (HfO2) gate dielectrics are investigated by examining the impact of oxygen and forming gas anneals on the effective work function of Pt-HfO2-silicon capacitors. The effective platinum work function is ∼4.6eV when annealed in forming gas. However, diffusion of oxygen to the Pt∕HfO2 interface increases the platinum work function to a value of ∼4.9eV. Subsequent annealing in forming gas returns the platinum work function to a value comparable to that measured prior to the oxygen anneal. The effective platinum work functions are compared to the prediction of the metal induced gap states (MIGS) model. The presence of interfacial oxygen vacancies or platinum–hafnium bonds is believed to be responsible for a degree of pinning that is stronger than predicted from the MIGS model alone.

Electrochemically induced oxygen spillover and diffusion on Pt(111): PEEM imaging and kinetic modelling

“…If the UV light source cannot provide photons beyond this energy, the PEEM intensity will not decrease even with further increasing coverage. As the maximum energy of the used UV source (Osram HBO103W/2 lamp, B4.86 eV to B5.27 eV with an I max E 4.9 eV) is close to the Pt work function (4.6 eV-5.9 eV), 27,[43][44][45] this may well be the case in the present experiments. Depending on the exact work function of the investigated Pt film, only a part of the photons can be used, also explaining the observed low image intensity.…”

Electron spin resonance signature of the oxygen vacancy in HfO2

“…The defect undergoes a symmetry lowering polaron distortion to be localized mainly on a single adjacent Hf ion. 3,4 bias stress instability, 5,6 channel mobility reduction, 7 or band bending in the oxide next to a high work function gate electrode [8][9][10][11] has generally been attributed to oxygen vacancies. Similarly, non-volatile memories are now taking an increasing importance in modern portable electronics, where the non-volatile resistive random access memory (RRAM) is a leading candidate to superceded Flash memory technology.…”

<I>In-Situ</I> Transmission Electron Microscopy Investigation of the Interfacial Reaction between Er and SiO<SUB>2</SUB> Films

“…[5][6][7] However, substantially large threshold voltage (V th ) shifts and unacceptably high interface trap densities (D it ) serve as a major barrier to the applications of Hf-based dielectrics to deep submicron complementary metal-oxide-semiconductor (CMOS) technology. 8,9) Recently, Choi et al investigated the electrical and structural properties of high-k Er-silicate films formed by the interfacial reaction between Er and SiO 2 films, and showed that the increase of the rapid thermal annealing (RTA) temperature results in a reduction of the interface trap density, and an increase of the relative dielectric constant of the Er-silicate film, which is compatible with the standard CMOS flow. 10) However, detailed knowledge of Er-SiO 2 interfacial reaction is insufficient for further development of its physical properties.…”