TiCl4 Barrier Process Engineering in Semiconductor Manufacturing
Titanium nitride (TiN) not only was utilized in the wear-resistant coatings industry but it was also adopted in barrier processes for semiconductor manufacturing. Barrier processes include the titanium (Ti) and TiN processes, which are commonly used as diffusion barriers in via/contact applications. However, engineers frequently struggle at the via/contact module in the beginning of every technology node. As devices shrink, barrier processes become more challenging to overcome the both the physical fill-in and electrical performance requirements of advanced small via/contact plugs. The aim of this paper is to investigate various chemical vapor deposition (CVD) TiCl4-based barrier processes to serve the application of advanced small via/contact plugs and the metal gate processes. The results demonstrate that the plasma-enhanced chemical vapor deposition (PECVD) TiCl4-based Ti process needs to select a feasible process temperature to avoid Si surface corrosion by high-temperature chloride flow. Conventional high step coverage (HSC) CVD TiCl4-based TiN processes give much better impurity performance than metal organic chemical vapor deposition (MOCVD) TiN. However, the higher chloride content in HSC film may degrade the long-term reliability of the device. Furthermore, it is evidenced that a sequential flow deposition (SFD) CVD TiCl4-based process with multiple cycles can give much less chloride content, resulting in faster erase speeds and lower erase levels than that of conventional HSC TiN.
Multiscale plasma and feature profile simulations of plasma-enhanced chemical vapor deposition and atomic layer deposition processes for titanium thin film fabrication
Mechanisms of titanium (Ti) thin films deposited in plasma-enhanced (PE) chemical vapor deposition (CVD) and atomic layer deposition (ALD) processes have been elucidated via multiscale plasma and feature profile simulations. Firstly, by iterating a 2D reactor-scale plasma simulation and a feature-scale deposition profile simulation, a shared surface reaction model has been determined for PECVD processes. Ti film thicknesses and profiles consistently computed both along a wafer surface and inside a test structure agreed very well with the experimental data. Then, another multiscale simulation, with the same plasma model and the surface reaction model to which the Eley–Rideal surface kinetics is added, has been applied to a PEALD process. The simulation succeeded again in reproducing and explaining the non-conformal Ti film deposition observed in experiments, while conformal Ti films are obtained in PECVD processes. Through the simulation work, comprehensive mechanisms of Ti film deposition, which cover both PECVD and PEALD processes, have been discussed and proposed in this study.
Photoreflectance characterization of vanadium-doped GaAs layers grown by metalorganic vapor phase epitaxy
Abstract We characterized the vanadium-doped (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy. The conductivity of the samples is checked by the Hall effect measurements, and it is n type with electrons concentration ranging from 2×10 13 to 2×10 17  cm −3 . We used the photoreflectance technique (PR) to study the effect of vanadium doping on the optical properties of GaAs. Our experimental results show that the built-in electric field F and the broadening parameter Γ 0 increase with V-doping concentration. Furthermore, the temperature dependence of the built-in electric field and the broadening parameter of GaAs:V samples have been investigated by PR. It has been observed that these parameters increase with increasing temperature. The decrease of the built-in electric field with decreasing temperature is due to the photovoltage effect.We characterized the vanadium-doped GaAs (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy.