1/12/2022 1 1 EE4409 Modern Microelectronic Devices and Sensors Prof. Hong Minghui (FSEng, FOSA , FSPIE, FIAPLE & FIES) Room No: E2 - 04 - 09 Tel: 6516 - 1636 E - mail: elehmh@nus.edu.sg Lecture 2 Course Introduction Chapter 2 Microelectronics Devices 2.1 Case Study: Optical Microsphere Nanoscope 2.2 Semiconductor Doping 2.3 Diode, BJT, FET & MOSFET Course Introduction This module introduces some microelectronics devices applicable to IoT systems/applications in modern gadgets/ equipment: smartphones , wearable electronics & driverless cars. The devices include sensors to detect various types of physical parameters (temperature, speed & position) and storage devices etc. The working principles will be described leading to applications. Their specifications , usability & key features will be analysed so that students will learn how to utilize the devices for wide range IoT related applications , such as healthcare and transportation. 1/12/2022 2 One of my successful technology commercialization projects Case Study 1: Development of Optical Microsphere Nanoscope at 100 nm and beyond 1/12/2022 3 Nikon COOLPIX P900 Optical Microscope and Its Impacts on Our Life Human hair Bacteria - kitchen 6 Research Need : A microscope magnifies tiny objects. 1/12/2022 4 0.61 ~ sin 61 0 n d Resolution Minimum optical imaging of current light microscope in air: 200 nm Abbe’s limitation (19 th century): Spatial resolution is limited by optical diffraction, which is about a half of light wavelength. 7 Where: d - smallest feature size; - wavelength of optical light; n - refractive index of medium; - incident angle. Technical Issue : SEM, TEM, AFM & NSOM but expensive setups ($0.5~1M), working in high vacuum or near field, slow imaging, impossible for extensive applications. S canning near field optical microscop e Scanning electron microscope Atomic Force Microscope Current Technologies: Pros & Cons 1/12/2022 5 Super - resolved Fluorescence Microscopy: STED Awarded 2014 Nobel Prize in Chemistry. Optical imaging in air ~30nm. Challenges: To dope fluorescence materials, complicated setup, expensive, slow imaging, impossible for extensive applications. Current Technologies: Pros & Cons Nat. Commun. 2, 218 (2011) Feature 50nm, pitch 100nm , bright field in air Microsphere sitting on sample surface 10 Our New Discovery 1/12/2022 6 Microsphere : (small ball lens, size: 5 ~ 10s μm) Novel Design and Working Principle 3 years research funding support @ S$5millions from National Research Foundation (NRF) Competitive Research Project (CRP ) Our Technology Development 1/12/2022 7 A complex pattern of flower with ~ 50 nm linewidth is distinguished by optical microsphere nanoscope (NA 1 4 oil lens, 405 nm) 13 Our Technology Breakthrough Literature Review Report 2 – Reference 1/12/2022 8 15 Modality Resolutio n Need for Fluorescence Sample Preparation Acquisition Time Image Processing Working Distance Standard fluorescence microscopy 250nm Yes Yes Extremely short (real - time) No 0.1 - 2.75mm SIM 100nm Yes Yes Short (seconds) Yes (Fourier transforms) 0.1 - 0.2mm STED 30 - 70nm Yes Yes Short (seconds) No ~100 μ m PALM/fPALM 10 - 55nm Yes Yes Long (minutes) Yes (centroid identification) ~100 μ m STORM/ dSTORM 10 - 55nm Yes Yes Long (minutes) Yes (centroid identification) ~100 μ m NSOM 10nm No No Very Long (>half an hour) No ~20nm Microsphere 23nm No No Extremely short (real - time) No ~ μ m SEM 0.5 - 1nm No Yes Extremely short (real - time) Yes - 16 Feature Comparisons 1/12/2022 9 Our Nanoscope image SEM image Magnetic Head Slide (Actual industrial sample) Novel Design and Working Principle 176 nm 115 nm IC Chip (Actual industrial sample) 1 μ m Optical Microsphere Nanoscope SEM image Novel Design and Working Principle 1/12/2022 10 Novel Design and Working Principle 20 × objective lens ( without microsphere) 20 × objective lens ( with microsphere) Onion Skin Cells Imaging Comparison Novel Design and Working Principle Basic Physics: Enlarged Virtual Imaging Virtual image Virtual magnified (2.5 times) image 1/12/2022 11 Impacts to Our Society and Economics Values to the Market • Non - contact mode + High resolution + Optical imaging + Simple system • Which means: - Non - contact : Non - sample damaging, view high aspect ratio Can view soft samples without pre - treatment. - High resolution : View sub - 100nm features semiconductor, bio - samples (organelles in cells). - Optical : Non - sample preparations needed in - vivo imaging, especially important for observing interactions in live cells. - Simple system : Easy and safe to operate, without special trainings. Home, school, clinic and lab: much lower price Failure analyses of semiconductors: sub 100 - nm resolution Tiny crack detection in aerospace industry: working in air Biological live cell in - vivo observation: pure optical imaging Virus DNA Chemical Molecules Impacts to Our Society and Economics 1/12/2022 12 For students to explore Nano - world with fun For teachers to benefit from cloud education Impacts to Our Society and Economics Data Analyses Dynamic Detection Smart Sensing Safety Monitoring Impacts to Our Society and Economics 1/12/2022 13 Impacts to Our Society and Economics From Research to Products 137nm 1/12/2022 14 Development Progress from a concept to a product From Research to Products From Research to Products 1/12/2022 15 From Research to Products Optical Microsphere Microscope ( OptoNano 200 can see down to 137 nm) From Research to Products 137nm Phaos Technology has launched its first disruptive microsphere ‐ assisted microscopy technology, OptoNano 200 , in a collaboration with Sigma Koki Together we launched our revolutionary OptoNano 200 at the Photonics West 2020 , the leading event for the worldwide photonics industry The OptoNano 200 is now ready to accept customer orders , uses microsphere to upgrade the magnification of microscopes by up to 4 times using miniature glass spheres, enabling samples to be viewed in a way that is uncontaminated and intact, making a breakthrough in Life Science, Biomedical & Semiconductor applications As cited by Prof Hong Minghui, co ‐ founder and director of Phaos Technology, and Professor from the NUS, “The OptoNano technology is able to see smaller and better at an exceptionally cost - effective way With such a technology, we are able to make super ‐ resolution microscopy affordable to the masses ” 1/12/2022 16 OptoNano 200 Global Launch on 18 Nov 2020 From Research to Products Videos: 1. Phaos History 2. OptoNano 200 1/12/2022 17 2.2 Semiconductor Doping Resistivity at room temperature Semiconductor: electrical conductivity between metal and insulator. Silicon : Energy bandgap (Eg): 1.12 eV Crystalline silicon ingots and wafers 3.2 Semiconductor Doping Energy bandgap depends on temperature 1/12/2022 18 Case Study 2: Si Purification (with samples) 36 1/12/2022 19 2.2 Semiconductor Doping Doping P (Donor) into Si to form n - type Si Doping B (Acceptor) into Si to form p - type Si Beauty of Semiconductor • Doping concentration: 10 13 ~10 19 cm - 3 , LOW compared to number of silicon atoms (5x 10 22 cm - 3 Si); but HIGH compared to Si intrinsic carrier concentration at its operating temperatures (10 10 cm - 3 at 25 0 C). • By controlling doping , we can flexibly tune semiconductor’s conductivity then its electric characteristics. 2.2 Semiconductor Doping Beauty of Semiconductor 1/12/2022 20 2.2 Semiconductor Doping Applications • Consider a Si substrate with an initial doping of N A = 2x10 15 cm - 3 acceptors. Si is thus p - type , with a hole concentration of 2x10 15 cm - 3 • We now selectively dope a volume with N D = 5x10 15 cm - 3 donors. • As there are more donors than acceptors, the selected volume is now n - type with an electron concentration of n = N D – N A = 3x10 15 cm - 3 • In this way, we have made a p - n junction. 2.3 Diode, BJT, FET & MOSFET • Semiconductor diode is basically a pn junction. • Diode is the simplest and most fundamental non - linear circuit element. It allows a current to flow through it easily in one direction , but not in the opposite direction (unlike a resistor). As such, it can be used in a rectifier circuit, to convert ac signal into dc signal. • pn junction is the basic element of bipolar junction transistors (BJTs) and field - effect transistors (FETs), which are widely used in electronic circuits. “Real” Diode Ideal Diode I V Reverse breakdown Reverse current I + - R V Diode: Design and Structures