Quantum Mechanical Simulation of Ultra Thin SOIMOSFETs

Research Project

Project/Area Number	14550332
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	電子デバイス・機器工学
Research Institution	Toyo University
Principal Investigator	TOYABE Toru Toyo University, Faculty of Engineering, Professor, 工学部, 教授 (20266993)
Co-Investigator(Kenkyū-buntansha)	花尻達郎東洋大学, 工学部, 助教授 (30266994)
Project Period (FY)	2002 – 2003
Project Status	Completed (Fiscal Year 2003)
Budget Amount *help	¥1,100,000 (Direct Cost: ¥1,100,000) Fiscal Year 2003: ¥200,000 (Direct Cost: ¥200,000) Fiscal Year 2002: ¥900,000 (Direct Cost: ¥900,000)
Keywords	SOIMOSFET / Fully Inverted Type / Quantum Effect / Simulation / Schroedinger Equation / Field Dependent Mobility / シュレーデインガー方程式
Research Abstract	We proposed a fully inverted SOI(Silicon-On-Jnsulator)MOSFETs which have as thin silicon top layer as inversion layer of k-3 nm. Since the thickness of the top silicon layers for this devices is 1〜3 nm, electrons in the layer are in quantum mechanical 2-D states. In the quantum mechanical modeling electron density has maximum in the midst of the silicon layer and thus the transconductance is expected to be lower than that predicted from classical modeling. The electron density distribution in the silicon layer is determined from quantum mechanical self-consistent potential distribution and the electrons produces transport phenomena with dissipative nature due to scattering under the drain voltage biasing. In order to know electrical characteristics such as threshold voltage, subthreshold characteristics and drain current under strong inversion and saturation conditions, quantum mechanical modeling is mandatory. In 2002, we improved simulation accuracy by including a field dependent mobility into our simulator which is based on lateral integration of 1D Schroedinger Poisson self-consistent solutions. In 2003, we analyzed threshold voltages of fully inverted SOIMOSFETs with thin silicon layer whose thickness is in a range of 2.5〜500 nm using our simulator. It is shown that the quantum mechanical threshold voltage shift can be explained by the ground state energy of 2D electrons shfted from the bottom of conduction band and the effective gate, oxide thickness shift produced by the quantum mechanical electron distribution.