A Review and Analysis of Automatic Optical Inspection and Quality Monitoring Methods in Electronics Industry

Electronics industry is one of the fastest evolving, innovative, and most competitive industries. In order to meet the high consumption demands on electronics components, quality standards of the products must be well-maintained. Automatic optical inspection (AOI) is one of the non-destructive techniques used in quality inspection of various products. This technique is considered robust and can replace human inspectors who are subjected to dull and fatigue in performing inspection tasks. A fully automated optical inspection system consists of hardware and software setups. Hardware setup include image sensor and illumination settings and is responsible to acquire the digital image, while the software part implements an inspection algorithm to extract the features of the acquired images and classify them into defected and non-defected based on the user requirements. A sorting mechanism can be used to separate the defective products from the good ones. This article provides a comprehensive review of the various AOI systems used in electronics, micro-electronics, and opto-electronics industries. In this review the defects of the commonly inspected electronic components, such as semiconductor wafers, flat panel displays, printed circuit boards and light emitting diodes, are first explained. Hardware setups used in acquiring images are then discussed in terms of the camera and lighting source selection and configuration. The inspection algorithms used for detecting the defects in the electronic components are discussed in terms of the preprocessing, feature extraction and classification tools used for this purpose. Recent articles that used deep learning algorithms are also reviewed. The article concludes by highlighting the current trends and possible future research directions.Framework of the IQONIC Project; European Union’s Horizon 2020 Research and Innovation Program

Wide Bandgap Based Devices

Emerging wide bandgap (WBG) semiconductors hold the potential to advance the global industry in the same way that, more than 50 years ago, the invention of the silicon (Si) chip enabled the modern computer era. SiC- and GaN-based devices are starting to become more commercially available. Smaller, faster, and more efficient than their counterpart Si-based components, these WBG devices also offer greater expected reliability in tougher operating conditions. Furthermore, in this frame, a new class of microelectronic-grade semiconducting materials that have an even larger bandgap than the previously established wide bandgap semiconductors, such as GaN and SiC, have been created, and are thus referred to as “ultra-wide bandgap” materials. These materials, which include AlGaN, AlN, diamond, Ga2O3, and BN, offer theoretically superior properties, including a higher critical breakdown field, higher temperature operation, and potentially higher radiation tolerance. These attributes, in turn, make it possible to use revolutionary new devices for extreme environments, such as high-efficiency power transistors, because of the improved Baliga figure of merit, ultra-high voltage pulsed power switches, high-efficiency UV-LEDs, and electronics. This Special Issue aims to collect high quality research papers, short communications, and review articles that focus on wide bandgap device design, fabrication, and advanced characterization. The Special Issue will also publish selected papers from the 43rd Workshop on Compound Semiconductor Devices and Integrated Circuits, held in France (WOCSDICE 2019), which brings together scientists and engineers working in the area of III–V, and other compound semiconductor devices and integrated circuits

A transistor based sensing platform and a microfluidic chip for a scaled-up simulation of controlled drug release

The framework of my thesis are Biomedical (or Biological) Microelectromechanical Systems (BioMEMSs). Two fields in which this discipline is involved are sensors and fluidics. Functionalized organic materials are under investigation to be the means for target biological sensing, and sensors are evolving to be integrated in fluidics platforms in order to produce in the future new small portable diagnostic devices. On the other hand one of the challenges of micro and nanofluidic technology is the fabrication of drug release devices, in order to control the amount of drug present in an organism. In this thesis these two arguments are considered. First we will discuss the implementation of a process oriented to the fabrication of an hybrid Organic Field Effect Transistor (OFET) with sensing capabilities from the semiconductive layer. In the second part we will show the fabrication process of a silicon based structure for the scaled-up characterization of drugs in nanochannels for controlled drug release. The characterization will consider charged microspheres playing the role of drugs to be tracked with a microscope. We will highlight also the possibility of implementing the transistor related technology in nanofluidic systems for the electronic controlled drug release

Organic Photodiodes and Their Optoelectronic Applications

Recently, organic photodiodes (OPDs) have been acknowledged as a next-generation device for photovoltaic and image sensor applications due to their advantages of large area process, light weight, mechanical flexibility, and excellent photoresponse. This dissertation targets for the development and understanding of high performance organic photodiodes for their medical and industrial applications for the next-generation. As the first research focus, A dielectric / metal / dielectric (DMD) transparent electrode is proposed for the top-illumination OPDs. The fabricated DMD transparent electrode showed the maximum optical transmittance of 85.7 % with sheet resistance of 6.2 ohm/sq. In the second part of the thesis, a development of novel transfer process which enables the dark current suppression for the inverted OPD devices will be discussed. Through the effort, we demonstrated OPD with high D* of 4.82 x 10^12 Jones at reverse bias of 1.5 V with dark current density (Jdark) of 7.7 nA/cm2 and external quantum efficiency (EQE) of 60 %. Additionally in the third part, we investigate a high performance low-bandgap polymer OPD with broadband spectrum. By utilizing the novel transfer process to introduce charge blocking layers, significant suppression of the dark current is achieved while high EQE of the device is preserved. A low Jdark of 5 nA/cm2 at reverse bias of 0.5 V was achieved resulting in the highest D* of 1.5 x 10^13 Jones. To investigate the benefit for the various OPD applications, we developed a novel 3D printing technique to fabricate OPD on hemispherical concave substrate. The techniques allowed the direct patterning of the OPD devices on hemispherical substrates without excessive strain or deformation. Lastly, a simulation of the OPD stacked a-ITZO TFT active pixel sensor (APS) pixel with external transimpedance amplifier (TIA) readout circuit was performed.PHDElectrical & Computer Eng PhDUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/137168/1/hyunskim_1.pd

Electromagnetic Metasurface Fabricated by Printed Electronics and Its Applications

Recently, metasurface plays significant roles in manipulation of electromagnetic waves. The main fabrication methods are MEMS (Microelectromechanical systems) technology and PCB (Printed circuit board) technology. Both methods face the challenges of complex fabrication processes, high cost, and severe pollution. In this thesis, the digitalized reaction on demand (DRoD) method, as a new printed electronic technology, was proposed to address the problems. In this method, the substrate was coated by PVA and nanoparticle composite to form a mesoporous ink absorption layer, followed by reduction functionalization. A novel silver ink was formulated to solve the problems of low conductivity, nozzle blocking, and complex preparing processing. As a demonstration, EM metasurface was fabricated via digitally and precisely control of silver reduction reaction. Moreover, a roll to roll process of metasurface printing via DRoD method was demonstrated. The developed technology provides a solution to produce metasurface with low cost, high quality, and large scale

Organic Thin Film Transistor Integration

This thesis examines strategies to exploit existing materials and techniques to advance organic thin film transistor (OTFT) technology in device performance, device manufacture, and device integration. To enhance device performance, optimization of plasma enhanced chemical vapor deposited (PECVD) gate dielectric thin film and investigation of interface engineering methodologies are explored. To advance device manufacture, OTFT fabrication strategies are developed to enable organic circuit integration. Progress in device integration is achieved through demonstration of OTFT integration into functional circuits for applications such as active-matrix displays and radio frequency identification (RFID) tags. OTFT integration schemes featuring a tailored OTFT-compatible photolithography process and a hybrid photolithography-inkjet printing process are developed. They enable the fabrication of fully-patterned and fully-encapsulated OTFTs and circuits. Research on improving device performance of bottom-gate bottom-contact poly(3,3'''-dialkyl-quarter-thiophene) (PQT-12) OTFTs on PECVD silicon nitride (SiNx) gate dielectric leads to the following key conclusions: (a) increasing silicon content in SiNx gate dielectric leads to enhancement in field-effect mobility and on/off current ratio; (b) surface treatment of SiNx gate dielectric with a combination of O2 plasma and octyltrichlorosilane (OTS) self-assembled monolayer (SAM) delivers the best OTFT performance; (c) an optimal O2 plasma treatment duration exists for attaining highest field-effect mobility and is linked to a “turn-around” effect; and (d) surface treatment of the gold (Au) source/drain contacts by 1-octanethiol SAM limits mobility and should be omitted. There is a strong correlation between the electrical characteristics and the interfacial characteristics of OTFTs. In particular, the device mobility is influenced by the interplay of various interfacial mechanisms, including surface energy, surface roughness, and chemical composition. Finally, the collective knowledge from these investigations facilitates the integration of OTFTs into organic circuits, which is expected to contribute to the development of new generation of all-organic displays for communication devices and other pertinent applications. A major outcome of this work is that it provides an economical means for organic transistor and circuit integration, by enabling use of the well-established PECVD infrastructure, yet not compromising the performance of electronics

Investigation of structural properties of organic thin films for solar cell and transistor applications

For the past several decades, organic materials including polymers, oligomers and small molecules have been of great interest for their various applications in the electronics and the semiconductor industry. The most appealing advantages of organic materials compared to their inorganic counterparts are their compatibility with flexible substrates and amenability to low-temperature and low-cost fabrication processes such as evaporation, spin-coating and printing. Moreover, the ability to be utilized in fabrication of lightweight and large-area devices is among other reasons for popularity of organic materials. A large number of studies have reported on various aspects of the development and optimization of organic electronics such as organic light emitting diodes (OLEDs), solar cells (OSCs) and thin film transistors (OTFTs). Although significant progress has been made during this period, some of the intrinsic electrical properties of organic materials such as low carrier mobility have continued to hinder the full development and maturation of the organic electronics industry. In order to manufacture organic electronic devices with high performance, more detailed studies of the structure and the morphology of the organic materials as well as the underlying physical charge transport mechanisms should be performed. Additionally, growth, deposition and assembly processes need to be established and optimized for the new organic semiconductor technology.;This work aims to advance the understanding of the effect of the structural properties of organic thin films on the charge carrier transport within the organic thin films as well as the charge carrier injection between the organic layers and the organic-inorganic materials such as metal or dielectric layers. Charge carrier transport mechanisms between different layers are crucial factors in determining the efficiency of organic electronic devices. These parameters rely largely on the molecular structure, morphology and ordering of the organic thin films. In order to investigate these intrinsic properties, several organic thin films were prepared using vacuum thermal evaporation method. Their morphology and structural properties were studied by the combination of various techniques including atomic force microscopy, X-ray reflectivity, spectroscopic ellipsometry and transmittance measurements. Based on the produced organic thin films, organic semiconductor devices such as OTFTs and OSCs were fabricated and their electrical and optical properties were characterized. Moreover, the effect of morphology and structure of the organic thin films on the organic device performance was studied. Ambipolar thin film transistors based on pentacene and PTCDI-C8 as the active layer and lithium fluoride (LiF) as the gate dielectric layer were fabricated and characterized. Conduction behaviors of these devices were modeled using Fowler-Nordheim (FN) tunneling theory. The results of this study suggest that the charge transport in OTFTs correlate not only with the organic semiconductor film structure, but also with the dielectric--semiconductor interfacial effects. Moreover, bilayer heterojunction OSCs based on CuPc/PTCDI-C8 as the donor/acceptor layers were fabricated and their electrical and optical properties were characterized. The effects of the active layers\u27 structures and morphologies as well as the buffer layers\u27 thickness variation on the device performance were studied. The results of this study emphasized the importance of the thin film structural properties on the device performance

High-throughput large-area plastic nanoelectronics

Large-area electronics (LAE) manufacturing has been a key focus of both academic and industrial research, especially within the last decade. The growing interest is born out of the possibility of adding attractive properties (flexibility, light weight or minimal thickness) at low cost to well-established technologies, such as photovoltaics, displays, sensors or enabling the realisation of emerging technologies such as wearable devices and the Internet of Things. As such there has been great progress in the development of materials specifically designed to be employed in solution processed (plastic) electronics, including organic, transparent metal oxide and nanoscale semiconductors, as well as progress in the deposition methods of these materials using low-cost high-throughput printing techniques, such as gravure printing, inkjet printing, and roll-to-roll vacuum deposition. Meanwhile, industry innovation driven by Moore’s law has pushed conventional silicon-based electronic components to the nanoscale. The processes developed for LAE must strive to reach these dimensions. Given that the complex and expensive patterning techniques employed by the semiconductor industry so far are not compatible with LAE, there is clearly a need to develop large-area high throughput nanofabrication techniques. This thesis presents progress in adhesion lithography (a-Lith), a nanogap electrode fabrication process that can be applied over large areas on arbitrary substrates. A-Lith is a self-alignment process based on the alteration of surface energies of a starting metal electrode which allows the removal of any overlap of a secondary metal electrode. Importantly, it is an inexpensive, scalable and high throughput technique, and, especially if combined with low temperature deposition of the active material, it is fundamentally compatible with large-area fabrication of nanoscale electronic devices on flexible (plastic) substrates. Herein, I present routes towards process optimisation with a focus on gap size reduction and yield maximisation. Asymmetric gaps with sizes below 10 nm and yields of > 90 % for hundreds of electrode pairs generated on a single substrate are demonstrated. These large width electrode nanogaps represent the highest aspect ratio nanogaps (up to 108) fabricated to date. As a next step, arrays of Schottky nanodiodes are fabricated by deposition of a suitable semiconductor from solution into the nanogap structures. Of principal interest is the wide bandgap transparent semiconductor, zinc oxide (ZnO). Lateral ZnO Schottky diodes show outstanding characteristics, with on-off ratios of up to 106 and forward current values up to 10 mA for obtained upon combining a-Lith with low-temperature solution processing. These unique devices are further investigated for application in rectifier circuits, and in particular for potential use in radio frequency identification (RFID) tag technology. The ZnO diodes are found to surpass the 13.56 MHz frequency bernchmark used in commercial applications and approach the ultra-high frequency (UHF) band (hundreds of megahertz), outperforming current state of the art printed diodes. Solution processed fullerene (C60) is also shown to approach the UHF band in this co-planar device configuration, highlighting the viability of a-Lith for enabling large-area flexible radio frequency nanoelectronics. Finally, resistive switching memory device arrays based on a-Lith patterned nanogap aluminium symmetric electrodes are demonstrated for the first time. These devices are based either on empty aluminium nanogap electrodes, or with the gap filled with a solution-processed semiconductor, the latter being ZnO, the semiconducting polymer poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) or carbon nanotube/polyfluorene blends. The switching mechanism, retention time and switching speed are investigated and compared with published data. The fabrication of arrays of these devices illustrates the potential of a-Lith as a simple technique for the realisation of large-area high-density memory applications.Open Acces

Silicon thin films for mobile energy electronics

Consumer needs for mobile devices include the requirement for longer battery life, so that recharging can be performed less frequently or eliminated completely. To this end a key component of any mobile system is a high power and high energy density battery. An alternative to better batteries is for mobile devices to harvest some of their own energy. Solar energy is an accessible, free and environmentally friendly source of energy, making it ideal for powering mobile devices. In this work we present a low deposition temperature (150°C), thin-film solar power harvesting system. Low deposition temperature of thin film silicon and associated alloys allows for fabrication on plastic in order to realize lightweight and robust integrated systems. The system consists of a thin film transistor (TFT) circuit and thin film photovoltaic (PV) array. The circuit functions as a simple DC-DC regulator and maximum power point tracking unit (MPPT). Amorphous silicon (a-Si:H) is used as the primary thin-film material for the fabrication of the devices. One of the challenges when fabricating devices at low temperatures is the high defect density in a-Si:H due to hydrogen clustering. In here the He in addition to the SiH4 and H2 is used to minimise hydrogen clustering. Using the optimised films, TFT and PV devices are fabricated, and analysed. Low deposition temperatures influence TFT properties. Contact resistance and dynamic instability of TFTs are considered. New extraction methods and their effect on device mobility are presented. A power conditioning TFT circuit is proposed. A model is developed to analyse the circuit’s output stability as a function of stressing and light intensity. System efficiency and its dependence on circuit efficiency and solar cell utilisation are discussed. The PV array and the TFT circuit are fabricated using lithography techniques, with a maximum process temperature of 150°C. The circuit can provide a degree of output power stability over a wide range of light intensities and stressing times, making it suitable for use with SC. In this work peak system efficiency of 18% is achieved. Despite the circuit’s low efficiency, it has the advantage of fabrication on plastic substrates and better integrability within mobile devices