DOCSLIB.ORG

Novel Technologies for Next Generation Memory

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Novel Technologies for Next Generation Memory Novel Technologies for Next Generation Memory WookHyun Kwon Tsu-Jae King Liu, Ed. Vivek Subramanian, Ed. Electrical Engineering and Computer Sciences University of California at Berkeley Technical Report No. UCB/EECS-2013-136 http://www.eecs.berkeley.edu/Pubs/TechRpts/2013/EECS-2013-136.html July 25, 2013 Copyright © 2013, by the author(s). All rights reserved. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission. Acknowledgement I would like express my sincere gratitude to my advisor, Professor Tsu-Jae King Liu. Prof. King Liu truly inspire me to do better, and I am always looking forward your advices because she always give great feedback. I am deeply grateful to Professor Vivek Subramanian for his enthusiastic class, especially EE231. He has a superior teaching techniques that lead students to have intuitions on the device. I hope he keeps teaching, during whole life. Novel Technologies for Next Generation Memory By Wookhyun Kwon A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Engineering - Electrical Engineering and Computer Sciences in the Graduate Division of the University of California, Berkeley Committee in charge: Professor Tsu-Jae King Liu, Chair Professor Vivek Subramanian Professor Junqiao Wu Fall 2013 Novel Technologies for Next Generation Memory Copyright © 2013 by Wookhyun Kwon Abstract Novel Technologies for Next Generation Memory by Wookhyun Kwon Doctor of Philosophy in Engineering – Electrical Engineering and Computer Sciences University of California, Berkeley Professor Tsu-Jae King Liu, Chair Historically, our society requires computational memory media to support the development of our civilization. It is likely that our society will keep demanding larger capacity memory. However, conventional memory technologies are facing many challenges such as difficulties of miniaturization and guarantee of good reliability. For this reason, alternate memory device designs are proposed to overcome the conventional memory device technologies. For DRAM technology, a double-gate array having vertical channel structure (DGVC) with 4F2 cell size is proposed, which can be fabricated on a bulk silicon wafer using the conventional memory process flow for stand-alone DRAM application. The operation and scalability of the DGVC cell are demonstrated via TCAD device simulations. For Flash Memory technology, a new backside charge storage non-volatile memory (BCS-NVM) cell design is proposed. A NAND flash array of the BCS-NVM cells can be fabricated on a modified SOI substrate. TCAD device simulation show that this design allows for a relatively high cell read current and steep sub-threshold slope to enable lower voltage operation in comparison with conventional NAND flash memory devices. As a new concept of non-volatile memory technology, a nano-electro-mechanical (NEM) diode non-volatile memory cell design is proposed. This design eliminates the need of a selector device to form a cross-point array, by leveraging the gap closing actuator. The electro-mechanical diode cell design can be scaled to 20 nm minimum lateral dimension by following an appropriate scaling methodology in consideration of various practical and fundamental limits. Low-voltage (< 2 V) and high-speed (sub-nanosecond) operation are projected using a calibrated analytical model as well as 3-D FEM simulation. These findings indicate that electro-mechanical diode technology is promising for high density storage beyond the limits of conventional flash memory technology. 1 To my wife for her devoted love and support, to my daughters for their sincere smile, and to my parents for their unbounded love. i Contents Table of Contents ii List of Figures vi List of Tables x Acknowledgements xi Table of Contents Chapter 1: Introduction ………………………......………..……………1 1.1 Overview of Computer Memory Technologies …..……….………………………...1 1.2 Dynamic Random Access Memory (DRAM) ..………………...……………….…2 1.2.1 Conventional DRAM and Limitations .…………………………….2 1.2.2 Capacitor-less DRAM Technology …………..………….………….4 1.2.3 Doubly-Gated Capacitor-less DRAM Technology .....….……..…...6 1.3 Flash Memory .…………………………………………………………………..8 1.3.1 History of Flash Memory Technology ………………..…………..8 1.3.2 Limitations of conventional Flash memory technology ……..…..11 ii 1.4 Emerging Memory Technology ……………….……………………………..…13 1.4.1 Cross-point Memory ………………………..………..…………..13 1.4.2 Mechanical Switch Memory …………………………..……..…..14 1.5 Research Objectives and Thesis Overview ……….……………………………..…17 1.6 References …………………………………………………….………………...18 Chapter 2: Highly Scalable Capacitor-less DRAM Cell having a Doubly Gated Vertical Channel ……………….....19 2.1 Introduction ………………………………..……………………………………19 2.2 Device Architecture and Proposed Fabrication …..……………………………......20 2.3 Cell Operation ………………………………...……………………………......23 2.4 Disturbances in the Cell Array ……………………………………....................26 2.5 Scalability of DGVC …………………………………………………....................27 2.6 Summary ………………………………………………..……………....................29 2.7 References ……………………………………………………………....................29 iii Chapter 3: A New NAND Flash Memory Cell Design Utilizing a Back Gate Structure …………………..……...31 3.1 Introduction ………………………………..……………………………………31 3.2 Device Structure .………………….……………………………………………......33 3.3 Proposed Fabrication Process .….…………………….………………................34 3.3.1 Silicon-On-ONO-Substrate (SOONOS) Formation .………………………...34 3.3.2 Memory Device Fabrication …………….……………………………….36 3.4 Device Simulation of the BCS-NVM Cell …………….........................................37 3.4.1 Basic Cell Operation ...............................................………………………...38 3.4.2 Disturbance Immunities...........................................………………………...40 3.5 Summary ..….……………………………………………...................................41 3.6 References ….……………………………………………...................................42 Chapter 4: Electro-Mechanical Diode Non-Volatile Memory Cell …….…………………...……………..……...43 4.1 Introduction ………………………………..……………………………………43 4.2 Device Structure ……………………………………………...….……………...44 4.3 Fabrication Process for Proto-type Cell ……………………..………………….....48 4.4 Electrical Measurement of the Proto-type Cell …...………………………………..51 iv 4.5 Suppression of Sneak Leakage Currents in the Cell Array .……………………..55 4.6 Reliability …….………………………………………………………………....56 4.7 Modeling and Analysis of Electrical Behavior …………………………………..58 4.7.1 Set Operation ............................................……............…………………...58 4.7.2 Reset Operation ……...........................................………………………...60 4.8 Scaling Theory of Electro-Mechanical Diode Cell ..................................................62 4.9 Exemplary Design for 20nm Electro-Mechanical Diode Cell .................................65 4.11 3-Dimensional Integration .....................................................................................66 4.12 Summary ...............................................................................................................67 4.13 References ..............................................................................................................67 Chapter 5: Conclusion ……………………………………….…………69 5.1 Summary …………………..………………………………..…………………….69 5.2 Contribution of This Work …………………………………………………………70 5.3 Suggested Future Work …………………………………………..……………….71 v List of Figures 1.1 Technology trend of conventional DRAM 2 1.2a Comparison between a conventional 8F2 and new 6F2 layout design 3 1.2b Example of 6F2 layout schematic 3 1.3 Recessed-Channel-Access-Transistor (RCAT) structures in DRAM technology 4 1.10a Common-Source NOR-type array architecture 9 1.4 Schematic cross-sectional view of a capacitor-less DRAM 5 1.5 TEM image of a fabricated capacitor-less DRAM cell 5 1.6 Schematic cross-sectional view of a capacitor-less DRAM on SOI 6 1.7 Schematic cross-sectional view and TEM image of a typical independently-Controlled- Double-Gate Floating-Body-Cell device 7 1.8 Channel length vs. Allowable body thickness in a doubly gate capacitor-less DRAM cell design 7 1.9 Schematic cross-section of the conventional flash memory cell 8 1.10a Common-Source NOR-type array architecture 9 1.10b NAND-type array architecture 9 1.11 Photo-lithographic resolution trends 10 1.12 NAND Flash memory revenue trend of the past 15 years 10 1.13 Cross-sectional TEM image of 25nm NAND Flash memory cell 11 1.14 The number of electrons stored in the NAND Flash cell’s floating gate 12 1.15 Example of mechanical switch memory in daily life 14 1.16 Illustration of micro-electro-mechanical non-volatile memory cell 14 1.17a TEM image of Nano-mechanical NVM cell using CMOS back-end process 15 1.17b Illustration of the operaion of Nano-mechanical NVM cell 15 1.18a Schematic cross-section of NEMory cell 16 1.18b Fundamental theory of NEMory operation 16 2.1a Schematic cross-sectional view of DGVC cells 21 2.1b Schematic plan view of DGVC array 21 2.2 Circuit schematic of a DGVC cell array 21 2.3 Key process steps for DGVC array 22 2.4 Simulated retention characteristics of a DGVC cell 25 2.5 Simulated non-destructive readout characteristic of a DGVC cell 25 2.6a Write “0” disturbance on the unselected
Load more

Recommended publications
  • Graphene Field-Effect Transistor Array with Integrated Electrolytic Gates Scaled to 200 Mm
    Graphene field-effect transistor array with integrated electrolytic gates scaled to 200 mm N C S Vieira1,3, J Borme1, G Machado Jr.1, F Cerqueira2, P P Freitas1, V Zucolotto3, N M R Peres2 and P Alpuim1,2 1INL - International Iberian Nanotechnology Laboratory, 4715-330, Braga, Portugal. 2CFUM - Center of Physics of the University of Minho, 4710-057, Braga, Portugal. 3IFSC - São Carlos Institute of Physics, University of São Paulo, 13560-970, São Carlos-SP, Brazil E-mail: [email protected] Abstract Ten years have passed since the beginning of graphene research. In this period we have witnessed breakthroughs both in fundamental and applied research. However, the development of graphene devices for mass production has not yet reached the same level of progress. The architecture of graphene field-effect transistors (FET) has not significantly changed, and the integration of devices at the wafer scale has generally not been sought. Currently, whenever an electrolyte-gated FET (EGFET) is used, an external, cumbersome, out-of-plane gate electrode is required. Here, an alternative architecture for graphene EGFET is presented. In this architecture, source, drain, and gate are in the same plane, eliminating the need for an external gate electrode and the use of an additional reservoir to confine the electrolyte inside the transistor active zone. This planar structure with an integrated gate allows for wafer-scale fabrication of high-performance graphene EGFETs, with carrier mobility up to 1800 cm2 V-1 s-1. As a proof-of principle, a chemical sensor was achieved. It is shown that the sensor can discriminate between saline solutions of different concentrations.
    [Show full text]
  • Advanced MOSFET Structures and Processes for Sub-7 Nm CMOS Technologies
    Advanced MOSFET Structures and Processes for Sub-7 nm CMOS Technologies By Peng Zheng A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Engineering - Electrical Engineering and Computer Sciences in the Graduate Division of the University of California, Berkeley Committee in charge: Professor Tsu-Jae King Liu, Chair Professor Laura Waller Professor Costas J. Spanos Professor Junqiao Wu Spring 2016 © Copyright 2016 Peng Zheng All rights reserved Abstract Advanced MOSFET Structures and Processes for Sub-7 nm CMOS Technologies by Peng Zheng Doctor of Philosophy in Engineering - Electrical Engineering and Computer Sciences University of California, Berkeley Professor Tsu-Jae King Liu, Chair The remarkable proliferation of information and communication technology (ICT) – which has had dramatic economic and social impact in our society – has been enabled by the steady advancement of integrated circuit (IC) technology following Moore’s Law, which states that the number of components (transistors) on an IC “chip” doubles every two years. Increasing the number of transistors on a chip provides for lower manufacturing cost per component and improved system performance. The virtuous cycle of IC technology advancement (higher transistor density lower cost / better performance semiconductor market growth technology advancement higher transistor density etc.) has been sustained for 50 years. Semiconductor industry experts predict that the pace of increasing transistor density will slow down dramatically in the sub-20 nm (minimum half-pitch) regime. Innovations in transistor design and fabrication processes are needed to address this issue. The FinFET structure has been widely adopted at the 14/16 nm generation of CMOS technology.
    [Show full text]
  • Fundamentals of MOSFET and IGBT Gate Driver Circuits
    Application Report SLUA618A–March 2017–Revised October 2018 Fundamentals of MOSFET and IGBT Gate Driver Circuits Laszlo Balogh ABSTRACT The main purpose of this application report is to demonstrate a systematic approach to design high performance gate drive circuits for high speed switching applications. It is an informative collection of topics offering a “one-stop-shopping” to solve the most common design challenges. Therefore, it should be of interest to power electronics engineers at all levels of experience. The most popular circuit solutions and their performance are analyzed, including the effect of parasitic components, transient and extreme operating conditions. The discussion builds from simple to more complex problems starting with an overview of MOSFET technology and switching operation. Design procedure for ground referenced and high side gate drive circuits, AC coupled and transformer isolated solutions are described in great details. A special section deals with the gate drive requirements of the MOSFETs in synchronous rectifier applications. For more information, see the Overview for MOSFET and IGBT Gate Drivers product page. Several, step-by-step numerical design examples complement the application report. This document is also available in Chinese: MOSFET 和 IGBT 栅极驱动器电路的基本原理 Contents 1 Introduction ................................................................................................................... 2 2 MOSFET Technology ......................................................................................................
    [Show full text]
  • Work Function and Process Integration Issues of Metal
    WORK FUNCTION AND PROCESS INTEGRATION ISSUES OF METAL GATE MATERIALS IN CMOS TECHNOLOGY REN CHI NATIONAL UNIVERSITY OF SINGAPORE 2006 WORK FUNCTION AND PROCESS INTEGRATION ISSUES OF METAL GATE MATERIALS IN CMOS TECHNOLOGY REN CHI B. Sci. (Peking University, P. R. China) 2002 A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING NATIONAL UNIVERSITY OF SINGAPORE OCTOBER 2006 _____________________________________________________________________ ACKNOWLEGEMENTS First of all, I would like to express my sincere thanks to my advisors, Prof. Chan Siu Hung and Prof. Kwong Dim-Lee, who provided me with invaluable guidance, encouragement, knowledge, freedom and all kinds of support during my graduate study at NUS. I am extremely grateful to Prof. Chan not only for his patience and painstaking efforts in helping me in my research but also for his kindness and understanding personally, which has accompanied me over the past four years. He is not only an experienced advisor for me but also an elder who makes me feel peaceful and blessed. I also greatly appreciate Prof. Kwong from the bottom of my heart for his knowledge, expertise and foresight in the field of semiconductor technology, which has helped me to avoid many detours in my research work. I do believe that I will be immeasurably benefited from his wisdom and professional advice throughout my career and my life. I would also like to thank Prof. Kwong for all the opportunities provided in developing my potential and personality, especially the opportunity to join the Institute of Microelectronics, Singapore to work with and learn from so many experts in a much wider stage.
    [Show full text]
  • New Applications of Organic Polymers in Chemical Gas Sensors
    New Applications of Organic Polymers in Chemical Gas Sensors Neue Einsatzmöglichkeiten organischer Polymere in chemischen Gassensoren Dissertation der Fakultät für Chemie und Pharmazie der Eberhard-Karls-Universität Tübingen zur Erlangung des Grades eines Doktors der Naturwissenschaften 2005 vorgelegt von Mika Harbeck Tag der mündlichen Prüfung: 18.11.2005 Dekan: Prof. Dr. S. Laufer 1. Berichterstatter: PD Dr. U. Weimar 2. Berichterstatter: Prof. Dr. G. Gauglitz Contents 1. Introduction 1 1.1. Introduction to the Field ...................... 1 1.2. Motivation and Scope ....................... 4 1.3. Overview of the Presented Work ................. 5 2. Theoretical Background and Related Work 7 2.1. Sorption Processes ......................... 7 2.2. Electrochemical Aspects of Interfaces .............. 11 2.3. The Chemical and Physical Structure of the Electrical Double Layer................................. 16 2.4. Measuring the Work Function and Surface Potentials ..... 30 2.5. Chemical Sensing with Field Effect Devices ........... 41 3. Experimental Details 51 3.1. Instrumental Equipment ...................... 51 3.2. Materials for the Preparation of the Sensing Layers ...... 59 3.3. Polymer Deposition ......................... 64 3.4. Measurement Procedure ...................... 70 4. Sensitive Layer Morphology: Characterisation and Optimization 73 4.1. Polyacrylic Acid Layers ...................... 74 4.2. Polystyrene Layers ......................... 81 4.3. Poly-(4-vinylphenol) Layers .................... 84 4.4. Poly-(acrylonitrile-co-butadiene) Layers ............. 86 4.5. Poly-(cyanopropyl-phenyl-siloxane) Layers ........... 87 4.6. Summary ............................... 87 5. Response to Analyte Gases 89 5.1. Inert Reference Material and Uncoated Substrates ....... 89 5.2. Polyacrylic Acid Coated Substrates ................ 91 5.3. Polystyrene Coated Substrates .................. 114 5.4. Poly-(4-vinylphenol) Coated Substrates ............. 122 5.5. Poly-(acrylonitrile-co-butadiene) Coated Substrates .....
    [Show full text]
  • Embedded Non-Volatile 1T Floating- Gate Memories: Technological and Physical Challenges for Augmenting Performance Towards the 28 Nm Node
    THÈSE Pour obtenir le grade de DOCTEUR DE L’UNIVERSITÉ GRENOBLE ALPES Spécialité : Nano électronique et nano technologies Arrêté ministériel : 25 mai 2016 Présentée par Adam DOBRI Thèse dirigée par Prof. Francis BALESTRA préparée au sein du Laboratoire Institut de Microélectronique, Electromagnétisme et Photonique - Laboratoire d'hyperfréquences et de caractérisation dans l'École Doctorale d’Électronique, Électrotechnique, Automatique et Traitement du Signal Embedded Non-volatile 1T floating- gate memories: technological and physical challenges for augmenting performance towards the 28 nm node Mémoires embarquées non-volatiles à grille flottante: challenges technologiques et physiques pour l’augmentation des performances vers le nœud 28 nm Thèse soutenue publiquement le 13 Juillet 2017, devant le jury composé de : Monsieur Gérard GHIBAUDO Directeur de recherche CNRS Alpes, Président Monsieur Albdelkader SOUIFI Professeur, INL/INSA de Lyon, Rapporteur Monsieur Pascal MASSON Professeur, Université de Nice Sophia Antipolis, Rapporteur Monsieur Francis BALESTRA Directeur de recherche CNRS Alpes, Directeur de thèse Acknowledgements The old proverb that “it takes a village to raise a child” can easily be scaled to become “it takes an entire team to train a PhD student” as there is no way that I could have succeeded in this work without the support of my co-workers and peers in many different places. In keeping with the spirit of my time in Grenoble the acknowledgements will be written in a mixture of French and English; I will try my best to avoid ST-isms that do not exist in either language. Je voudrais d’abord remercier mon directeur de thèse, Francis Balestra, et mon manager à ST, Fausto Piazza, d’avoir accepté d’encadrer cette thèse sur les mémoires flash.
    [Show full text]
  • Study of Metal Gates and Ge Channel Devices
    University of Central Florida STARS Electronic Theses and Dissertations, 2004-2019 2007 Gate Stack And Channel Engineering: Study Of Metal Gates And Ge Channel Devices Ravi Todi University of Central Florida Part of the Electrical and Electronics Commons Find similar works at: https://stars.library.ucf.edu/etd University of Central Florida Libraries http://library.ucf.edu This Doctoral Dissertation (Open Access) is brought to you for free and open access by STARS. It has been accepted for inclusion in Electronic Theses and Dissertations, 2004-2019 by an authorized administrator of STARS. For more information, please contact [email protected]. STARS Citation Todi, Ravi, "Gate Stack And Channel Engineering: Study Of Metal Gates And Ge Channel Devices" (2007). Electronic Theses and Dissertations, 2004-2019. 3387. https://stars.library.ucf.edu/etd/3387 GATE STACK AND CHANNEL ENGINEERING: STUDY OF METAL GATES AND Ge CHANNEL DEVICES by RAVI M. TODI B.E.E.E. Mumbai University, 2002 M.S.E.E., University of Central Florida, 2004 M.S.M.E., University of Central Florida, 2005 A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the School of Electrical Engineering and Computer Science in the College of Engineering and Computer Science at the University of Central Florida Orlando, Florida Spring Term 2007 Major Professors: Kevin R. Coffey Kalpathy B. Sundaram © 2007 Ravi M. Todi ii ABSTRACT The continued scaling of device dimensions in complementary metal oxide semiconductor (CMOS) technology within the sub-100 nm region requires an alternative high dielectric constant (high-κ) oxide layer to counter high tunneling leakage currents, a metallic gate electrode to address polysilicon depletion, boron penetration and high polysilicon sheet resistance, and high mobility channel materials to boost the CMOS performance.
    [Show full text]
  • Recent Advances in Electric-Double-Layer Transistors for Bio-Chemical Sensing Applications
    sensors Review Recent Advances in Electric-Double-Layer Transistors for Bio-Chemical Sensing Applications Ning Liu 1,2, Ru Chen 1 and Qing Wan 2,* 1 Nanchang Institute of Technology, Nanchang 330099, China 2 School of Electronic Science & Engineering, Nanjing University, Nanjing 210093, China * Correspondence: [email protected]; Tel.: +86-791-88126923 Received: 28 June 2019; Accepted: 1 August 2019; Published: 5 August 2019 Abstract: As promising biochemical sensors, ion-sensitive field-effect transistors (ISFETs) are used widely in the growing field of biochemical sensing applications. Recently, a new type of field-effect transistor gated by ionic electrolytes has attracted intense attention due to the extremely strong electric-double-layer (EDL) gating effect. In such devices, the carrier density of the semiconductor channel can be effectively modulated by an ion-induced EDL capacitance at the semiconductor/ electrolyte interface. With advantages of large specific capacitance, low operating voltage and sensitive interfacial properties, various EDL-based transistor (EDLT) devices have been developed for ultrasensitive portable sensing applications. In this article, we will review the recent progress of EDLT-based biochemical sensors. Starting with a brief introduction of the concepts of EDL capacitance and EDLT, we describe the material compositions and the working principle of EDLT devices. Moreover, the biochemical sensing performances of several important EDLTs are discussed in detail, including organic-based EDLTs, oxide-based EDLTs, nanomaterial-based EDLTs and neuromorphic EDLTs. Finally, the main challenges and development prospects of EDLT-based biochemical sensors are listed. Keywords: ISFET; electric-double-layer; electrolyte-gated transistor; biosensor; chemosensor 1. Introduction Biochemical species detection techniques have important applications in the area of homeland security, medical and environmental monitoring, bioscience research and also food safety.
    [Show full text]
  • Self-Aligned-Gate Gallium Oxide Metal-Oxide-Semiconductor Transistors
    78 Technology focus: Gallium oxide Self-aligned-gate gallium oxide metal-oxide-semiconductor transistors Researchers see such a process as being ‘essential’ for future devices with high performance and ultra-low power losses. esearchers based in the USA and Germany bandgap (~4.8eV). The related high estimated critical claim the first demonstration of self-aligned gate field (~8MV/cm) is some 2–3x higher than for R(SAG) β-polytype gallium oxide (β-Ga2O3) wide-bandgap materials such as gallium nitride or metal-oxide-semiconductor field-effect transistors silicon carbide. (MOSFETs) [Kyle J. Liddy et al, Appl. Phys. Express, vol12, p126501, 2019]. The researchers at KBR Inc and the Air Force Research Labora- tory in the USA and Leibniz-Institut für Kristallzüchtung (IKZ) in Germany used a refrac- tory metal gate-first design with silicon (Si) ion-implantation to eliminate source access resistance, giving some of the highest trans- conductance values reported so far for β-Ga2O3 MOSFETs. The US part of the team was sited at the Wright–Patterson Air-Force Base, Ohio. The researchers see such a SAG process as being “essential for future β-Ga2O3 device engineering to achieve high-performance, ultra-low-power-loss devices”. It is only recently that β-Ga2O3 has been seri- ously considered as a Figure 1. (a) Schematic of SAG β-Ga2O3 MOSFET, (b) top-down scanning electron semiconductor material microscope image of representative 2x50µm SAG MOSFET with dashed line indicating for use in high-efficiency cross-sectioned region, (c) transmission electron microscope (TEM) image of gated power applications, region, and high-resolution TEM images of (d) W gate electrode, gate oxide and based on its ultra-wide β-Ga2O3 substrate, and (e) gate oxide and implanted β-Ga2O3 channel.
    [Show full text]
  • Field Effect Transistors
    Field Effect Transistors Lecture 9 Types of FET • Metal Oxide Semiconductor Field Effect Transistor – MOSFET – Enhancement mode – Depletion mode • Junction FETs • p channel vs n channel 38 Metal Oxide Semiconductor Field Effect Transistor MOSFET (NMOS) Enhancement Mode • Consists of Four terminals – Drain which is n-doped material G S D – Source also n-doped material Oxide – Base which is p-doped material Metal Gate Drain – Gate is a metal and is insulated from the Drain, Source Source and Base by a thin layer of silicon dioxide ~ .05-.1mm thick • Basically, an electric current flowing from drain to source, iD, is controlled by the amount of voltage n+ n+ (electric field) appearing between the gate and base p (note that the base and source are usually tied together and therefore, it is referred to as the gate to source voltage or gate voltage), vGS. Substrate, body or Base • iD flows through a channel of n-type material which B is induced by vGS. The amount of iD is a function of the thickness of the channel and the voltage between drain and source, vDS • However, the thickness of channel is controlled by the level of gate voltage. (The width, .5 to 500 mm, and length, .2 to 10 mm, of the channel is shown in the diagram.) 39 Metal Oxide Semiconductor Field Effect Transistor MOSFET (NMOS) Enhancement Mode • Consists of Four terminals – Drain which is n-doped material – Source also n-doped material G – Base which is p-doped material S D – Gate is a metal and is insulated from the Drain, Oxide Source and Base by a thin layer of silicon Metal Gate Drain dioxide ~ .05-.1mm thick Source • Basically, an electric current flowing from drain to source, iD, is controlled by the amount of voltage (electric field) appearing between the gate and base W (note that the base and source are usually tied n+ L n+ together and therefore, it is referred to as the gate to p source voltage or gate voltage), vGS.
    [Show full text]
  • MOSFET Device Physics and Operation
    1 MOSFET Device Physics and Operation 1.1 INTRODUCTION A field effect transistor (FET) operates as a conducting semiconductor channel with two ohmic contacts – the source and the drain – where the number of charge carriers in the channel is controlled by a third contact – the gate. In the vertical direction, the gate- channel-substrate structure (gate junction) can be regarded as an orthogonal two-terminal device, which is either a MOS structure or a reverse-biased rectifying device that controls the mobile charge in the channel by capacitive coupling (field effect). Examples of FETs based on these principles are metal-oxide-semiconductor FET (MOSFET), junction FET (JFET), metal-semiconductor FET (MESFET), and heterostructure FET (HFETs). In all cases, the stationary gate-channel impedance is very large at normal operating conditions. The basic FET structure is shown schematically in Figure 1.1. The most important FET is the MOSFET. In a silicon MOSFET, the gate contact is separated from the channel by an insulating silicon dioxide (SiO2) layer. The charge carriers of the conducting channel constitute an inversion charge, that is, electrons in the case of a p-type substrate (n-channel device) or holes in the case of an n-type substrate (p-channel device), induced in the semiconductor at the silicon-insulator interface by the voltage applied to the gate electrode. The electrons enter and exit the channel at n+ source and drain contacts in the case of an n-channel MOSFET, and at p+ contacts in the case of a p-channel MOSFET. MOSFETs are used both as discrete devices and as active elements in digital and analog monolithic integrated circuits (ICs).
    [Show full text]
  • High- /Metal–Gate Stack and Its MOSFET Characteristics
    408 IEEE ELECTRON DEVICE LETTERS, VOL. 25, NO. 6, JUNE 2004 High- /Metal–Gate Stack and Its MOSFET Characteristics Robert Chau, Senior Member, IEEE, Suman Datta, Member, IEEE, Mark Doczy, Brian Doyle, Jack Kavalieros, and Matthew Metz Abstract—We show experimental evidence of surface phonon be more effective in screening the high- ’s SO phonons from scattering in the high- dielectric being the primary cause coupling to the channel under inversion conditions [14], [15]. of channel electron mobility degradation. Next, we show that On the other hand, metal–gate electrodes with the correct work midgap TiN metal–gate electrode is effective in screening phonon scattering in the high- dielectric from coupling to the channel functions are required for high-performance CMOS logic appli- under inversion conditions, resulting in improved channel electron cations on bulk Si [16]. mobility. We then show that other metal–gate electrodes, such To understand the various physical scattering mechanisms as the ones with n+ and p+ work functions, are also effective in that limit channel electron mobility in the high- dielectric, improving channel mobilities to close to those of the conventional we experimentally measure the effective inversion electron SiOP/poly-Si stack. Finally, we demonstrate this mobility degra- dation recovery translates directly into high drive performance mobility as a function of temperature and transverse electric on high- /metal–gate CMOS transistors with desirable threshold field in the HfO /poly-Si stack, and conclude that voltages. surface phonon scattering is the primary cause of electron Index Terms—Atomic layer deposition (ALD), CMOS transis- mobility degradation in the HfO .
    [Show full text]