Browsing by Author "Sze, Simon Min"

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Overview of emerging nonvolatile memory technologies
(2014-09-25)
Meena, Jagan Singh
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Sze, Simon Min
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Chand, Umesh
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Tseng, Tseung-Yuen
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電子工程學系及電子研究所
Nonvolatile memory technologies in Si-based electronics date back to the 1990s. Ferroelectric field-effect transistor (FeFET) was one of the most promising devices replacing the conventional Flash memory facing physical scaling limitations at those times. A variant of charge storage memory referred to as Flash memory is widely used in consumer electronic products such as cell phones and music players while NAND Flash-based solid-state disks (SSDs) are increasingly displacing hard disk drives as the primary storage device in laptops, desktops, and even data centers. The integration limit of Flash memories is approaching, and many new types of memory to replace conventional Flash memories have been proposed. Emerging memory technologies promise new memories to store more data at less cost than the expensive-to-build silicon chips used by popular consumer gadgets including digital cameras, cell phones and portable music players. They are being investigated and lead to the future as potential alternatives to existing memories in future computing systems. Emerging nonvolatile memory technologies such as magnetic random-access memory (MRAM), spin-transfer torque random-access memory (STT-RAM), ferroelectric random-access memory (FeRAM), phase-change memory (PCM), and resistive random-access memory (RRAM) combine the speed of static random-access memory (SRAM), the density of dynamic random-access memory (DRAM), and the nonvolatility of Flash memory and so become very attractive as another possibility for future memory hierarchies. Many other new classes of emerging memory technologies such as transparent and plastic, three-dimensional (3-D), and quantum dot memory technologies have also gained tremendous popularity in recent years. Subsequently, not an exaggeration to say that computer memory could soon earn the ultimate commercial validation for commercial scale-up and production the cheap plastic knockoff. Therefore, this review is devoted to the rapidly developing new class of memory technologies and scaling of scientific procedures based on an investigation of recent progress in advanced Flash memory devices.
Role of environmental and annealing conditions on the passivation-free in-Ga-Zn-O TFT
(2011-12-30)
Fuh, Chur-Shyang
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Sze, Simon Min
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Liu, Po-Tsun
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Teng, Li-Feng
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Chou, Yi-Teh
We examined the characteristics of passivation-free amorphous In-Ga-Zn-O thin film transistor (a-IGZO TFT) devices under different thermal annealing atmospheres. With annealing at higher temperature, the device performed better at the above-threshold operation region, which indicated the film quality was improved with the decrease of defects in the a-IGZO active region. The mobility, threshold voltage and subthreshold swing of a-IGZO TFT annealed at 450 degrees C was 7.53 cm(2)/V s, 0.71 V and 0.18 V/decade, respectively. It was also observed that the a-IGZO was conductive after thermal annealing in the vacuum, due to the ease of oxygen out-diffusion from the a-IGZO back channel. The oxygen deficiency resultantly appeared, and provided leaky paths causing electrical unreliability when TFT was turned off. In contrast, the annealing atmosphere full of O(2) or N(2) would suppress the oxygen diffusion out of the a-IGZO back channel. The worst Vth degradation of a-IGZO TFT after positive gate bias stress and negative gate bias stress (NGBS) was about 2 V and -2 V, respectively. However, the V(th) shift in the NGBS testing could be suppressed to -0.5 V in vacuum chamber. Material analysis methods including X-ray photoelectron spectroscopy and scanning electron microscopy were used to investigate the change of a-IGZO film after different thermal annealing treatments. The variation of O 1s spectra with different annealing atmospheres showed the consistence with our proposed models. (C) 2011 Elsevier B.V. All rights reserved.