Conduction mechanisms and an evidence for phonon-assisted conduction process in thin high-k HfxTiySizO films
Abstract Electrical behavior of high-k Hf x Ti y Si z O layers with different Hf:Ti ratios in the film have been investigated. The films are prepared by MOCVD using novel single-source precursors chemistry. Oxide and interface charges, leakage currents and conduction mechanisms are found to be a strong function of the film composition. The films with lower Hf content show lower level of oxide and interface charges and higher dielectric constant whereas those with higher Hf content have better leakage current properties. It is established that in the films with lower Hf content the conduction is governed by a phonon-assisted process. The change of the conduction mechanism from Poole–Frenkel emission to phonon-assisted tunneling is assigned to possible structural changes which take place when changing the composition of the films.
Si-doped aluminates for high temperature metal-gate CMOS: Zr-Al-Si-O, a novel gate dielectric for low power applications
We have investigated a new class of high K gate dielectric materials, Si-doped aluminates. These dielectrics, with TiN gates, can withstand high temperature CMOS processing and therefore do not require replacement gate technology. In this paper we focus on Si-doped zirconium aluminate (Zr-Al-Si-O), with K/spl sim/20. With the TiN gate stack subjected to the standard CMOS thermal budget, we have scaled this dielectric to t/sub eq//spl sim/1.2 nm with leakage current <50 mA/cm/sup 2/ and gate power budget <50 mW/cm/sup 2/, at IV. For high performance, low power CMOS, beyond SiO/sub 2/, doped-aluminum oxide (with K/spl sim/10) may be a viable alternate gate dielectric. Beyond aluminum oxide, aluminates (with K>15) may be viable alternate gate dielectrics.
Finite Difference Modeling on the Temperature Field of Substrate in Friction Surfacing
Friction surfacing is an advanced process of great potential, especially in the field of repair and reclamation of worn and damaged components. As a kind of thermal processing technology, the temperature profile and changes of the substrate in friction surfacing are important factors to get coatings of high quality. In this paper, the temperature field of the substrate during the process is simulated by finite difference method. The results are consistent with experiments, reappearing the temperature change of the substrate during friction surfacing, allowing further study on figuration and quality of coatings.