A.S.M. Zain

Design and optimization of TiSi x /HfO 2 channel vertical double gate NMOS device

This paper aims to propose a new structure of vertical double-gate NMOS device with titanium silicide (TiSi_x) and hafnium dioxide (HfO₂) are utilized as gates and an insulator correspondingly. The simulation and characterization of the proposed device were carried out by using ATHENA and ATLAS modules of Silvaco TCAD tools. The threshold voltage (V_TH) of the device was then optimized by tuning the correct level of halo implant dose, halo implant tilt, S/D implant energy and S/D implant tilt via the L₉ orthogonal array (OA) of Taguchi method. The vertical TiSi_x/HfO₂ channel vertical double-gate NMOS device has shown excellent device characteristics as the V_TH, drive current (I_ON), leakage current (I_OFF), I_ON/I_OFF ratio and subthreshold swing (SS) were observed to be 0.2101 V, 2235.3 μA/μm, 1.363E-15 A/μm, 1.64E12 and 58.76 mV/dec respectively. These results are within the expected requirement of high performance (HP) multi gate (MG) technology as predicted by International Technology Roadmap Semiconductor (ITRS) 2013.

Analyze of threshold voltage in SOI PMOSFET device using Taguchi method

The short-channel effect (SCE) is the main problem of many metal-oxide-semiconductor field-effect transistor (MOSFET) industries. A lot of studies addressing the SCE effect have been conducted. One of the methods used for this is called SOI (silicon-on-insulator) technology. This method has been proven to effectively reduce the SCE effect. In this research paper, the electrical characteristic of an 18 nm gate length SOI PMOSFET was analyzed based on the prediction of the International Technology Roadmap for Semiconductors (ITRS). The threshold voltage would be the key characteristic in this research. Four process parameters were used with two noise factors in order to conduct nine sets of experiments using the L9 orthogonal array Taguchi method. At the end of the experiment, the best setting that was predicted by the Taguchi method would be utilized for the purpose of verification. The result shows that VTH after the optimization approach is closer to the nominal value (-0.533V), that is, within the appropriate range of ITRS 2013.

Multi-response optimization in vertical double gate PMOS device using Taguchi method and grey relational analysis

Miniturization of MOSFET device leads to statistical variation of many process parameters that may cause the degradation of the device performance. Taguchi method has been applied as a tool to optimize the process parameter variation. Since, Taguchi method is only limited to the solution of a single response, it is combined with grey relational analysis (GRA) to solve multi-response optimization. This paper presents a proposed method to optimize halo implant energy, halo implant tilt angle, source/drain (S/D) implant energy and source/drain (S/D) implant tilt angle upon multiple performance characteristics of WSix/TiO2 channel vertical double-gate PMOS device. The normalized experimental results based on L9 Taguchi method are utilized to compute grey relational coefficients and grades. The final results show that the process parameters have been successfully optimized in obtaining a nominal threshold voltage (-0.1783 V), a high drive current (1539.1 μA/μm) and a low leakage current (6.749E-11 A/μm) which meet the International Technology Roadmap Semiconductor (ITRS) 2013 prediction for high performance logic multi-gate technology.

Optimization of Silicon-Based Fabrication Process Modeling for Optical Modulator

Silicon-based photonic devices have emerged as a high demand technology for a wide range of applications. Most of these devices can be realized by optical waveguides where it forms the basic structure for device construction. This project involved the optimization of silicon waveguide fabrication process modeling using Silvaco. The optimized silicon-based waveguide components are aimed to be implemented in future photonic devices such as optical modulators. The Taguchi methods are employed to study the influence of fabrication parameters variations on the fabrication performance such as etch rate and waveguide structure. Four fabrication parameters are investigated includes the diffusion temperature of the N - type channel, diffusion temperature of the P - type channel, silicon orientation and oxide thickness. The result shows that the temperature during the diffusion on an N - type channel has the most influence on the performance of the modulation efficiency of the silicon optical waveguide.

On the performance of Mach-Zehnder-Interferometer (MZI) optical modulator on silicon-on-insulator (SOI)

In recent years, there has been a significant interest in the development of optical waveguide modulators using Silicon-On-Insulator (SOI) substrates motivated by the potential to provide a reliable low-cost alternative to other photonic materials. Objective: In this paper, Multimode Interference (MMI) device is used to develop the MZI structure of the optical modulator. Meanwhile, the electrical part of the modulator utilizes the forward biased P-I-N structure. The effect of varying MMI width to the performance of the MZI optical modulator on SOI was investigated. The effect of varying MMI width to the insertion loss (IL), extinction ratio (ER) and modulation efficiency (VπL) of the device were carried out. Results: The investigated MMI widths are 22, 30 and 38 μm. Smallest MMI width, which is 22 μm has recorded the lowest value of insertion loss with 3.30 dB and the best extinction ratio of 25.60 dB. However, the best modulation efficiency was observed for the MMI width of 38 μm with 0.1696 V.cm. Conclusion: Appropriate selection of MMI width is vital to ensure optimum performance of the MZI modulator.