A comprehensive study of reducing the STI mechanical stress effect on channel-width-dependent I_dsat

Abstract

In this paper, the complex behavior of saturation drain current (I dsat ) dependence on channel width was investigated. We compared two types of devices and concluded that the variation of I dsat with changing width is determined by both the y-direction shallow trench isolation mechanical stress (y-stress) effect and the delta width effect. Moreover, a semi-empirical formula was proposed to describe the I dsat dependence on channel width, taking into account these two effects. To reduce the STI stress, we examined several process steps that may contribute to the stress development, and found that a high temperature post-liner-anneal step can obviously reduce the stress effect.

The Enhanced Role of Shallow-Trench Isolation in Ionizing Radiation Damage of Narrow Width Devices in 0.2 μm Partially-Depleted Silicon-on-Insulator Technology

“…STI stress results in a strained region in the active area, thus affecting the silicon bandgap, the diffusivity of impurities in silicon, and the mobility of both electrons and holes. [13] As the device scales in the width direction, the impact of STI stress becomes severe on the electrical parameter of the parasitic corner transistors, such as threshold voltage, saturation drain current, and off-state leakage current. For narrow devices where the STI spacing is smaller, there is more compressive stress, which may increase the doping concentration at the STI sidewall, increasing the threshold voltage of the parasitic back corner transistor.…”

STI stress-induced degradation of data retention time in DRAM and a new characterizing method for mechanical stress

“…The STI slope is the steepest at the center and decreases as the device moves toward the edge. The steeper slope of STI induces a larger mechanical stress in the active region [1]. However, the mechanism must be understood and an electrical parameter must be found which correlates well with the stress.…”

Measurement of V<inf>th</inf> variation due to STI stress and inverse narrow channel effect at ultra-low voltage in a variability-suppressed process

“…The change in dopant concentration in channel region near the sidewall is also known as a cause of INCE. Dopant concentration change originates from redistribution and segregation of dopants [13] or STI stress-enhanced diffusion [14]. This dopant redistri bution and segregation occur in narrow channel device, but can also be considered to be STI-induced effect.…”