The increasing demand for precise light control in biomedical research, especially in fields like optogenetics and liquid crystal elastomers (LCEs), has exposed the limitations of traditional light sources regarding precision, controllability, and size. To address these challenges, this research focuses on developing miniaturized LED matrix systems capable of producing high-precision, high-power customizable light patterns essential for complex biological experiments. Two mini LED matrix systems—a 48x32 matrix and a larger 160x160 matrix—were designed and developed to achieve precise modulation of light intensity and patterns. These systems were tailored to meet the rigorous requirements of optogenetic experiments, which demand precise control over cellular activities, and to explore the potential applications in light-responsive LCEs. Controlling the light-responsive behavior of LCEs is critical for advancements in soft robotics, artificial muscles, and other applications requiring adjustable light sources. The 48x32 mini LED matrix system was successfully applied to control cardiac activity through optogenetics, demonstrating its ability to modulate light for inducing and terminating arrhythmias precisely. Additionally, its integration into LCE experiments showed promise for broader biomedical applications. Building on this success, the development of a larger 160x160 mini LED matrix system extended the technology’s applicability, supporting larger-scale experimental setups and human-sized models. By providing innovative solutions to the challenges of precise light control in biomedical research, this work opens new possibilities for experimental and clinical applications, offering significant contributions to the field.

This dissertation explores the development and application of an interactive optoelectronics platform designed for the precise manipulation of heart rhythm using mini/micro LEDs, primarily within the context of optogenetic applications. The research uses advancements in LED technology for biomedical engineering, focusing on the design, fabrication, and characterization of LED matrix systems. Key objectives include the development of a 48x32
mini LED matrix system, characterized for its electrical, optical, and thermal properties, and evaluated for both interactive and scripted operations. Additionally, the thesis investigates the use of this matrix for optogenetic control of cardiac activities, including optical pacing, conduction block, and the induction and termination of arrhythmias, demonstrating the system’s capability to manipulate cardiomyocytes in vitro. Furthermore, a real-time interactive optoelectronic manipulation system is developed, featuring software for real-time
control and manipulation of optical patterns, incorporating fastmanipulation frame streaming, image processing, and customized calculations. The research also extends to designing an LED matrix of human atrial surface area and the associated driver for potential clinical applications. The conclusions underscore the feasibility and effectiveness of using LED-based optoelectronic systems for precise biological control, laying the groundwork for future biomedical research and clinical therapies, and highlighting the significance of
interdisciplinary approaches in advancing medical technologies.@en

Sintered silver is known for its high thermal and electrical conductivity and is considered a promising die attach material for wide bandgap semiconductors at high power. This study investigates the evolution of microstructure and mechanical properties of sintered silver materials during aging in different atmospheres. The study used a combination of experimental methods, including shear tests, scanning electron microscopy, and EBSD, to evaluate the effects of air and nitrogen atmospheres on the reliability of the material. Advanced simulation methods, such as dynamic Monte Carlo and phase field methods, were combined to predict grain growth and void evolution during aging. The results show that air aging accelerates grain growth and pore aggregation, and oxidation is suppressed in a nitrogen atmosphere. These findings provide insights into optimizing the sintering process to improve the long-term stability and performance of sintered silver in semiconductor packaging applications.

Microwave Induced Plasma (MIP) is an advanced decapsulation tool developed by Jiaco Instruments. The goal of this thesis is to optimise the current MIP system. There are two directions: 1. Improve the etching rate. 2. Find selectivity between different materials (Si, SiO2, SiN). The experiments are divided into two parts in total, improved cavity and CF4-based MIP machine etching selectivity experiment. The cavity experimental results demonstrate that high input power is the route to optimising MIP efficiency. Etch experiments demonstrate that the CF4/O2 gas recipe is effective in achieving etch selectivity and that temperature is a key factor influencing these etch selectivities.

This study deals with the challenge of warpage in power modules, vital components in the rapidly expanding electric and hybrid-electric vehicle industry. The variations in temperature during manufacturing, resulting in significant warpage changes, contribute to device cracks, delamination, and reduced reliability.
The primary focus is understanding and mitigating the warpage phenomenon in power module substrates. This warpage is induced by thermo-mechanical stresses during the assembly packaging process. The investigation begins by exploring the cause of warpage change by characterizing annealed copper properties and employing 2D finite element model (FEM) analysis. The study identifies plastic strain as the dominant cause of warpage change during process steps. Subsequently, a validated 3D FEM simulation model is developed to replicate practical annealing and sintering processes. Lastly, the project delves into factor analysis to identify critical variables influencing warpage. It underscores that balancing residual copper volume is crucial in warpage reduction. Additive and subtractive manufacturing techniques establish a correlation between the removal of copper volume and warpage reduction.

This project provides comprehensive insights into the manufacturing process of AMB substrate, warpage behavior, and effective strategies for reduction, constructing a solid foundation for future manufacturing and design.

Board-level reliability (BLR) looks at the reliability problem in the package and PCB interconnection, which is an important topic in microelectronics. The current criterion in the BLR test is to look if the connection is open, which can only detect the failure and there is no available method that can detect the degradation of the solder joints. This project mainly focuses on the degradation process of solder joints in board-level vibration tests and thermal cycle tests.

Special methods and test programs are developed tailored for two test vehicles, and some of the test results are collected and analyzed. Assisted by the failure analysis technique, the physical change of solder joints can be observed.

Findings in this study show the parameter shift during the solder joint degradation and also the mathematic model that describes the relationship between the crack of the solder joints and resistance increment.

Power electronics are an important technology used to convert electricity from a source like a battery or high voltage DC bus to more usable forms of electricity. This has to be done efficiently, reliably and without failures which is critical in applications like electric cars or datacenters. Power MOSFETs with upcoming SiC and GaN devices are an important building block used in these converters. Hence these power MOSFET devices have to be improved continuously to get a lower on resistance (R_DSon), a better thermal dissipation and lower parasitic losses. In this thesis we will take a look at the embedding of power MOSFETs inside a PCB to obtain these improvements. This new technology needs to be evaluated in terms of reliability, failure-modes and thermal/electrical performance. By designing,
manufacturing and testing a PCB with embedded devices. During manufacturing silver sintering has been used for attaching the die to a copper coin. In the end the manufacturing has been done successfully.
Testing showed an 18% lower R_DSon and a twice as low junction to ambient thermal impedance indicating a better performance compared to regular packaging.

Sensors are extremely valuable to this world. Without sensors, we would not be able to live as we do in this data-driven environment. Therefore, finding new ways to measure the matter around us is a continuous process. In this work, an addition to the new sensors is attempted, using materials that can withstand the most extreme circumstances. This work describes the process of designing, simulating, producing, measuring and validating a pressure sensor based on LPCVD Silicon Carbide.
The created sensor should be modular and back-end-of-line compatible. In addition, the sensor should measure pressures from 80Pa up to 1MPa at temperatures from room temperature to 600°C. Because of a favourable reaction to high temperatures, a capacitive sensor type that uses a sealed membrane for absolute pressure measurements is chosen.
Due to the large pressure range, the design has been split into three distinct parts, each with its specialised pressure range. A low-range for 80Pa to 100kPa, a mid-range sensor for 100kPa to 300kPa and a high-range sensor for 300kPa to 1MPa. To compensate for the nonlinearity in the device, two approaches are taken. One method splits the bottom electrodes, generating a more linear output with the correct division. This approach is used for low-and-mid-pressure devices. The other approach uses touch mode to decrease nonlinearity. After the membrane touches the bottom contact, a linear range is found. This approach is taken for the high-pressure device.
A flowchart has been developed based on the necessary layers to create the sensors. Using this flowchart, masks have been designed. During production, the process was adjusted, as delamination of the dielectric layer was observed. In addition, because of difficulty with sealing, the membrane is thicker than the original design.
During production, buckling of the membranes was observed. This causes the sensors to behave differently compared to the simulations. One effect the buckling may have caused is the reaction to temperature. This is opposite to the simulations. In addition, subjecting the sensors to a vacuum also causes behaviour opposite to what was intended. When high pressure is applied, the sensors do work as intended. Due to the design alterations and buckling effect, the sensors are less sensitive to pressure than intended. The best sensor has a sensitivity of 0.025 f F/100Pa compared to the designed 0.3 f F/100Pa. However, the output of the sensor is linear without needing the designed compensation techniques.

Wide band gap semiconductor has attracted significant industrial interest over the past decade with its superior properties: such as high critical electrical field, high thermal conductivity andwide band gap. Meanwhile many industries operating in harsh environments have long had demands for sensing solutions that function at high temperature. Current commercially available silicon-based temperature sensing IC has measure range limited to 155°C . This research work aims to develop a temperature sensor based on 4H silicon carbide with pronounced higher measurement range but comparable linearity. Furthermore, this work introduces silicon carbide based bipolar junction transistor (BJT) technology in the Else Kooi Lab (EKL).
Ratio-metric measurement technique from CMOS technology is adapted to eliminate PN diode and BJT’s non-linearity as a temperature sensor; and devices are implemented experimentally on epitaxial 4H-silicon carbide wafers in the EKL.
The characterization data shows that diode version sensor operates to 400 °C with a R2 value of 0.9963, the sensitivity under 1 mA constant current source is 4.8mV/°C . The BJT version operates to 200 °C with a R2 of 0.9965. In the future the sensor’s integration with pressure, gas, and other types of sensing solutions can provide a comprehensive sensing package. Such a package can be used to predict life time of critical components in harsh environment installations; and hence reduce the maintenance cost. Examples
of application scenarios include oil&gas exploration, industrial furnaces, geothermal extraction,and so on.

Many semiconductor sensors, particularly MEMS sensors such as inertial, temperature, pressure, and resonance sensors need a vacuum environment for optimal performance and sensitivity in addition to the improvement in their long-term reliability. With the rise of heterogeneous integration with the MEMS and ICs being integrated together, process compatibility becomes a very big issue. Cu is a desirable bonding and sealing material for low-temperature vacuum packaging of next-generation microsystems, as it is compatible with modern CMOS circuits and 3-D IC fabrication. Cu thermocompression bonding has been reported to achieve vacuum sealing at low temperatures, but these approaches need extremely flat and clean Cu surfaces or additional capping layers, and the overall bonding areas are still rather large.
To mitigate this, the use of copper nanoparticles as the sealing material has been proposed. In this study, the first successful demonstration of die and multi-die level hermetic sealing has been demonstrated using Copper nanoparticle paste as the sealing material for sealing ring widths as small as 8$\mu$ at a minimum temperature and pressure levels of 300$^\circ$C and 10 MPa respectively with average encapsulated pressure of 54.18 mbar. Moreover, the leak rate evaluation was conducted which revealed no discernable leakage over a period of 48 days. Finally, the bond shear test and a subsequent failure analysis revealed high densification of the Copper nanoparticles at the bond interface.

Since the unravelling of the Covid-19 pandemic, studying methods of virus inactivation have become more important than ever. Many studies focus on the chemical and optical methods of inactivation. Very limited work has been carried out in studying the electrical methods of virus inactivation. The work presented in this thesis attempts to pioneer a study that examines the effect of electric fields generated by micro-electrodes on the survival of the surrogate of the SARS CoV-2 virus.
For this purpose, electrodes with 7 different geometries were micro-fabricated and characterized. A liquid suspension of the phi-6 bacteriophage (a surrogate of the SARS virus) was tested on all the different electrodes with different input voltages, frequencies and medium parameters.
The study showed that the treatment on specific electrode designs tailored with specific voltage and medium parameters showed a decrease in the virus titer ranging from half a log to a maximum of 2 logs. These results are promising for the development of products like electric facemasks, micro-filters and m-TAS systems.

This thesis investigates the all-copper fine pitch bonding process with photoimageable underfill. NanoCU paste is used as interconnect material. A bi-layer photo resist structure is manufactured and lithographic stencil printing is used to apply nanoCu paste. A new underfill injection method is realized by using epoxy resin based photo resist as underfill layer. Adhesion of sample is extensively enhanced. Various bonding methods are developed including using AML bonder and Tresky pick-and-place bonder. Electrical measurements for sintered nanoCu interconnect are conducted, sheet resistance and contact resistance are studied.

Graphene is two-dimensional allotrope of carbon with a honeycomb-like lattice structure. It shows exceptional properties in electrical, optical, thermal, mechanical and chemical fields. And due to its excellent properties, it is being researched to be used in many applications such as, sensors, graphene transistors, opto-electronics, etc. To realize these applications in an industrial scale, reliable methods to grow and transfer graphene need to be developed. Methods such as chemical and mechanical exfoliation, chemical vapour deposition (CVD), etc. are a few methods which are used to synthesize graphene. And wet transfer, electrochemical delamination, etc, are a few methods to transfer graphene on to the required substrate. Graphene is sensitive to chemicals and processing steps, hence the properties/behaviour of graphene varies based on the fabrication and transfer technique used. Applied Nano-Layer(ANL) is a company based in Delft, that fabricates and transfers wafer-scale mono-layer graphene. Asmentioned before, the properties/behaviour of graphene changes based on the fabrication and transfer technique used. Therefore, in this thesis, the properties/behaviour of monolayer graphene provided by ANL, is analyzed. In this thesis, electrical properties like channel resistance, resistivity and mobility were analyzed. Also, the optical behaviour of graphene where pauli-blocking stops the absorption of light at dirac point, is analyzed. Few questions related to design of the process flow, working of the fabricated devices, propagation of light in the waveguides, modulation of light and effect of process flow on graphene, were answered to properly analyze the above stated properties/behaviour of graphene. First, a wafer-scale silicon waveguide was designed using COMSOL and BeamLab. The derived width of the waveguide was found to be for the values of 1 um to 4 um and the optimal cladding thickness was found to be 20 nm. Then, the designed waveguide structures were translated onto a mask that would be used in the fabrication of the electro-absorption modulators. Second, a cleanroom compatible process flow for the fabrication of Hall bars and electro-absorption optical modulators was designed and optimized. Several testing steps were performed to find the optimal parameters required in the process flow. Third, the hall bars and the optical modulators were fabricated in the clean room , Else-Kooi Lab(EKL), using the designed masks and process flows. The electrical properties were analyzed by extensively measuring the hall bars. As an example, the average channel resistance, dirac voltage, average resistivity and average mobility of a graphene hall bar with dimensions 2 um x 2 um was measured/calculated to be 6.74 k­, 75.9 V, 1.7 k­ and 1573.28 cm2/Vs respectively. Similarly, the values for 11 other dimensional devices were measured/calculated. The optical behaviour was analyzed by testing the electro-absorption optical modulator. A few waveguides were tested for propagation of light and a power of 0.8 uW wasmeasured for an input power of 0.6mW, which suggests that light successfully propagates though the waveguides. Graphene modulation was tested using back gate biasing and an average dirac voltage of 73.33 V was observed for 2 um x 2 um hall bar device on the optical modulator die. These two when done simultaneously theoretically should modulate light. Lastly, the impact of process flow on graphene/ graphene devices was checked. And a drastric fall to 30% working devices(for optical modulators) from 60% working devices (for hall bars) with increase in process flow steps concludes that the number of processing steps does affect the graphene/ graphene devices.

Since the outbreak of SARS-COV-2, various virus inactivation techniques have been applied to suppress the spread of virus. Ultraviolet exposure inactivation is an efficient approach to inactivate virus, within UV band, UV-C with comparatively higher energy. UV-C has been proved to inactivate viruses efficiently, while to figure out efficient inactivation approach, virus reduction rate as a function of UV-C wavelength with different viral sensitivity and quantitative exposure dose should be measured through experiments.
On the one hand, miniatured, energy-efficient and fully-customized UV-C light-emitting diodes (LED) offer possibility of switching wavelengths and adjusting quantitative optical properties, on the other hand, UV-C LEDs have been produced with the latest technology based on Aluminium gallium nitride (AlGaN).

~\\Multifunctional UV-C LED Virus Inactivation Experimental Platform is a system designed with replaceable UV-C wavelengths, controllable light intensity and exposure time for quantitative virology experiments. The system has an initial design for standard virology experimental equipment which offers a new and consistent tool for virus researchers. The Inactivation Platform has been assembled and utilized to perform several Influenza A (ssRNA virus) inactivation experiments in order to obtain reduction rate as a function of UV-C wavelength and exposure dose with Germicidal Curve and Inactivation Curve respectively.

~\\After inactivation experiments implementation and result analysis, the inactivation mechanism on the basis of molecular dynamic research theory and simulation is supposed to be figured out. Due to the complexity of proteins in virus, the research focuses on Nucleic Acid Bases (NABs) as target genetic viral material. The absorbed ultraviolet energy results in ultrafast decay, including molecular electronic transition, virus structure variation (Dimerization) theoretically. The absorbed energy along the band is revealed with Absorption Spectrum, and the potential electronic transition depends on the initial structure NABs, together with inside chemical bonds. When absorbed energy populates the molecules to transition state, ultrafast decay takes place because of the existence of Gibbs energy of activation. In the light of molecular dynamic simulation, it proves that compared to ground state, excited state leads to lower standard Gibbs energy of activation, causing higher reaction rate (faster inactivation speed).

THERMAL management is a very crucial step to ensure the reliability of Integrated Circuits (IC)s. The increase in power density has resulted in the formation of multiple, high-intensity, and non-uniform hotspots. This has not only affected the lifetime but also the performance of several devices. Optimization of the package design and layout are the methods investigated to solve this problem. In flip-chip packaging, each IC product varies with respect to power densities, die area, pin-count, laminate and PCB layers, etc. It is therefore important in understanding how the arrangement and geometry of each layer (in particular the interconnect layer) impacts the overall thermal management.

With the development of biomedical technology such as optogenetics, optoelectronics devices, especially light-emitting diode(LED), becomes wildly used in biomedical researches and applications. Unlike traditional illumination and display applications, biomedical applications have more unique requirements like intensity and response speed. The existing optoelectronics systems cannot fulfill all the requirements of biomedical applications. It is essential to design particular light sources and drivers to fill the blank area of biomedical-compatible optoelectronics systems. However, each biomedical application has its environment and setup. One specific optoelectronics system will not suitable for all circumstances. This work focuses on developing a methodology to design advanced optoelectronics driver systems for biomedical applications to solve this problem. It takes three steps to develop and verify the driver design methodology. The first step is producing a high-power biomedical array driving system to verify the array control strategy. UVC virus inactivation test platform, which successfully finishes virus inactivation test in Erasmus MC, is produced in this step. The second step is extending the array driver to the matrix driver. An interactive optoelectronics system is designed to perform optogenetics experiments in LUMC. Finally, aiming at the ultimate goal-implantable, self-powered driver feasibility research is performed to prove it is feasible to design a self-power optoelectronics driver system in the future.

Moisture absorbed by the hygroscopic polymers like molding compound and die-attach vaporizes during reflow lead to a high vapor pressure inside the electrical components lead to failure in the electrical device, named as popcorn failure. Popcorn failure in plastic encapsulated microcircuits has been a critical issue for electronic device reliability. Researches have been conducted on investigating the failure mechanism. Among all the factors that contributed to the failure, vapor pressure is one of the primary sources of stress that causes crack of the molding compound and delamination between critical interfaces. Numerous publications demonstrate the vapor pressure evolution and contributing factors with mathematical models, simulations, and tests. However, direct measurement of vapor pressure is not yet reported. This thesis presents the design and fabrication verification of a pressure sensor to measure the vapor pressure evolution in moisture-containing polymers at reflow temperatures. The specifications and requirements are extracted from the failure mechanism reported in the literature. A touch-mode capacitive pressure sensor with in-situ doped poly-SiC is designed to measure vapor pressure from atmospheric pressure to 8 MPa under reflow temperature up to 300 °C. Simulation on touch mode capacitive readout is performed to verify the design parameters and provide an estimation of device performance. The fabrication process is designed and conducted with several methods for crucial steps along with different structure dimensions to investigate an optimal solution. A complete fabricated device is achieved with measured initial capacitance from 12.3 to 26.7 pF for different sizes of diaphragms. The deviation between the measured results and simulation results due to fabrication problems is analyzed. Possible causes and solutions of problems that occurred in fabrication and measurement, such as unexpected upward bending of the diaphragm, leakage current between the capacitor electrode plate, and uniformity of SiC layer fabrication, are discussed. Problem correction, device optimization, complete characterization, and experiments for vapor pressure measurement in molding compound remain as future work.