The effect of the geometry aspect ratio on the silicon ellipse-shaped surrounding- gate field-effect transistor and circuit

Abstract

The silicon (Si) surrounding-gate metal-oxide-semiconductor field-effect transistor (MOSFET) has ultimate gate structures and is a potential candidate for use in next-generation high-performance nano-devices. However, because of limitations of the fabrication process, theoretically ideally round shape of the surrounding gate may not always guarantee. These limitations may lead to the formation of an ellipse-shaped surrounding gate with major (a) and minor (b) axes of different lengths. In this study, the effect of the geometry aspect ratio, a/b, on the dc and ac characteristics of the 16 nm gate ellipse-shaped surrounding-gate MOSFETs and circuits is examined by using a three-dimensional coupled device-circuit simulation technique. The dependences of electrical characteristics on the geometry aspect ratio are evaluated with reference to various device characteristics and the circuit properties, including the circuit gain, the 3 dB bandwidth, the unity-gain bandwidth, the rise/fall time and the delay time. In analog circuits, the device with an aspect ratio of less than 1 is promising because the short-channel effect is suppressed. However, for a digital circuit configuration, the transient response of the circuit relies on the charge/discharge capability of the transistor. Thus, a device with a large aspect ratio, such as 2, will be more suitable for digital applications.

Modeling Short-Channel Effect of Elliptical Gate-All-Around MOSFET by Effective Radius

“…Bangsaruntip et al [9] proposed the universality of SCE in undoped elliptical GAA MOSFETs. Li and Hwang [10] studied the aspect ratio effects of GAA MOSFETs by numerical simulations. In this letter, we derive a more generic approach to predict the SCE and Q on /Q off ratio of an elliptical GAA MOSFET by converting it into an equivalent circular structure.…”

Cross-Sectional Shape Effects of Gate-All-Around Nanowire Field-Effect Transistors

“…[1][2][3][4] For example, elliptical cross-sectional nanowires noticeably exhibit shape effects on device characteristics, which have been well modeled and reported. [5][6][7] Other gate-all-around nanowire cross sections were observed and reported, [1][2][3][4] including triangular, trapezoidal, rhombus shape, square, rectangular and elliptical. The crosssectional shape effects have also been studied in FinFET.…”

Tuning the noise margins of gate-all-around MOSFET based inverters through non-circular multi-channel architecture

“…The non-circular crosssection of practical GAA devices have provided a scope for the research community to further investigate the device and circuit performance utilizing such device cross-section. To cite some previous works related to the non-circular nature of GAA devices, Li and Hwang [14] investigated the effect of geometry AR on elliptical GAA MOSFETs and circuits. The universality of short channel effects in elliptical undoped-body silicon nanowire MOSFETs was proposed by Bangsaruntip et al [15].…”