A predictive MOSFET model is critical for early circuit design research. To accurately predict the characteristics of nanoscale CMOS, emerging physical effects, such as process variations and correlations among model parameters, must be included. In this paper, a new generation of predictive technology model (PTM) is developed to accomplish this goal. Based on physical models and early-stage silicon data, the PTM of bulk CMOS is successfully generated for 130- to 32-nm technology nodes, with an Leff of as low as 13 nm. The accuracy of PTM predictions is comprehensively verified: The error of I on is below 10% for both n-channel MOS and p-channel MOS. By tuning only ten primary parameters, the PTM can be easily customized to cover a wide range of process uncertainties. Furthermore, the new PTM correctly captures process sensitivities in the nanometer regime, particularly the interactions among Leff, Vth, mobility, and saturation velocity. A website has been established for the release of PTM: http://www.eas.asu.edu/~ptm

New Generation of Predictive Technology Model for Sub-45 nm Early Design Exploration

This paper focuses on approaches to continuing CMOS scaling by introducing new device structures and new materials. Starting from an analysis of the sources of improvements in device performance, we present technology options for achieving these performance enhancements. These options include high-dielectric-constant (high-k) gate dielectric, metal gate electrode, double-gate FET, and strained-silicon FET. Nanotechnology is examined in the context of continuing the progress in electronic systems enabled by silicon microelectronics technology. The carbon nanotube field-effect transistor is examined as an example of the evaluation process required to identify suitable nanotechnologies for such purposes.

Beyond the conventional transistor

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.

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Overview of emerging nonvolatile memory technologies

Predictive MOSFET model is critical for early circuit design research. To accurately predict the characteristics of nanoscale CMOS, emerging physical effects, such as process variations and physical correlations among model parameters, must be included. In addition, predictions across technology generations should be smooth to make continuous extrapolations. In this work, a new generation of predictive technology model (PTM) is developed to accomplish these goals. Based on physical models and early stage silicon data, PTM of bulk CMOS for 130nm to 32nm technology nodes is successfully generated. By tuning ten parameters, PTM can be easily customized to cover a wide range of process uncertainties. The accuracy of PTM predictions is comprehensively verified: for NMOS, the error of I/sub on/ is 2% and for PMOS, it is 5%. Furthermore, the new PTM correctly captures process sensitivities in the nanometer regime. A webpage has been established for the release of PTM (http://www.eas.asu.edu//spl sim/ptm).

New Generation of Predictive Technology Model for Sub-45nm Design Exploration

Supervisory Control and Data Acquisition(SCADA) systems are deeply ingrained in the fabric of critical infrastructure sectors. These computerized real-time process control systems, over geographically dispersed continuous distribution operations, are increasingly subject to serious damage and disruption by cyber means due to their standardization and connectivity to other networks. However, SCADA systems generally have little protection from the escalating cyber threats. In order to understand the potential danger and to protect SCADA systems, in this paper, we highlight their difference from standard IT systems and present a set of security property goals. Furthermore, we focus on systematically identifying and classifying likely cyber attacks including cyber-induced cyber-physical attack son SCADA systems. Determined by the impact on control performance of SCADA systems, the attack categorization criteria highlights commonalities and important features of such attacks that define unique challenges posed to securing SCADA systems versus traditional Information Technology(IT) systems.

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A Taxonomy of Cyber Attacks on SCADA Systems

Many modern electronic systems---including personal computers, PDAs, cell phones, network routers, smart cards, and networked sensors to name a few---need to access, store, manipulate, or communicate sensitive information, making security a serious concern in their design. Embedded systems, which account for a wide range of products from the electronics, semiconductor, telecommunications, and networking industries, face some of the most demanding security concerns---on the one hand, they are often highly resource constrained, while on the other hand, they frequently need to operate in physically insecure environments.Security has been the subject of intensive research in the context of general-purpose computing and communications systems. However, security is often misconstrued by embedded system designers as the addition of features, such as specific cryptographic algorithms and security protocols, to the system. In reality, it is a new dimension that designers should consider throughout the design process, along with other metrics such as cost, performance, and power.The challenges unique to embedded systems require new approaches to security covering all aspects of embedded system design from architecture to implementation. Security processing, which refers to the computations that must be performed in a system for the purpose of security, can easily overwhelm the computational capabilities of processors in both low- and high-end embedded systems. This challenge, which we refer to as the "security processing gap," is compounded by increases in the amounts of data manipulated and the data rates that need to be achieved. Equally daunting is the "battery gap" in battery-powered embedded systems, which is caused by the disparity between rapidly increasing energy requirements for secure operation and slow improvements in battery technology. The final challenge is the "assurance gap," which relates to the gap between functional security measures (e.g., security services, protocols, and their constituent cryptographic algorithms) and actual secure implementations. This paper provides an introduction to the challenges involved in secure embedded system design, discusses recent advances in addressing them, and identifies opportunities for future research.

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Security in embedded systems: Design challenges

This paper reports a full CMOS process using a combination of a TiN/W Metal Replacement Gate Transistor design with a high dielectric constant gate insulator of tantalum pentoxide over thin remote plasma nitrided gate oxide. MOS devices with high gate capacitances equivalent to that for <2 nm SiO/sub 2/ but having relatively low gate leakage are reported. Transistors with gate lengths near or below 0.1 /spl mu/m have good characteristics. Working CMOS circuits using Ta/sub 2/O/sub 5/ gate insulator are demonstrated for the first time.

CMOS metal replacement gate transistors using tantalum pentoxide gate insulator

An embodiment of the instant invention is a method of forming a dielectric layer, the method comprising the steps of: providing a semiconductor substrate (substrate 12), the substrate having a surface; forming an oxygen-containing layer (layer 14) on the semiconductor substrate; and subjecting the oxygen-containing layer to a nitrogen containing plasma (plasma 16) so that the nitrogen is either incorporated into the oxygen-containing layer (see regions 18, 19, and 20) or forms a nitride layer at the surface of the substrate (region 22). Using this embodiment of the instant invention, the dielectric layer can be substantially free of hydrogen. Preferably, the oxygen-containing layer is an SiO2 layer or it is comprised of oxygen and nitrogen (preferably an oxynitride layer). The plasma is, preferably, a high-density plasma. Preferably, a source of nitrogen is introduced to the plasma to form the nitrogen containing plasma. The source of nitrogen is preferably comprised of a material consisting of: N2, NH3, NO, N2 O, or a mixture thereof.

Method of forming thin silicon nitride or silicon oxynitride gate dielectrics

A method for forming integrated circuits having multiple gate oxide thicknesses. A high density plasma is used for selective plasma nitridation to reduce the effective gate dielectric thickness in selected areas only. In one embodiment, a pattern (12) is formed over a substrate (10) and a high density plasma nitridation is used to form a thin nitride or oxynitride layer (18) on the surface of the substrate (10) . The pattern (12) is removed and oxidation takes place. The nitride (or oxynitride) layer (18) retards oxidation (20b), whereas, in the areas (20a) where the nitride (or oxynitride) layer (18) is not present, oxidation is not retarded. In another embodiment, a thermal oxide is grown. A pattern is then placed that exposes areas where a thinner effective gate oxide is desired. The high density plasma nitridation is performed converting a portion of the gate oxide to nitride or oxynitride. The effective thickness of the combined gate dielectric is reduced.

Method of forming multiple gate oxide thicknesses using high density plasma nitridation

Stress-induced-leakage-current (SILC) is an important concern in ultrathin gate oxides because it may impose constraints on dielectric thickness scaling. We show that for oxides less than /spl sim/3.5 nm thick, interfacial traps generated from direct tunneling stress result in a sense voltage dependent SILC mechanism that can dominate the gate leakage current at low operating voltages.

Sunil V. Hattangady

Papers

Security in embedded systems: Design challenges

CMOS metal replacement gate transistors using tantalum pentoxide gate insulator

Method of forming thin silicon nitride or silicon oxynitride gate dielectrics

Method of forming multiple gate oxide thicknesses using high density plasma nitridation

Low voltage stress-induced-leakage-current in ultrathin gate oxides