In this thesis, we present a pragmatic heterogeneous integration strategy to obtain high-performance 3D electronic systems using existing CMOS technology. Critical challenges addressed during the process are; reliable flexible interconnects, maximum area efficiency, soft-polymeric packaging, and heterogeneous integration compatible with current CMOS technology. First, a modular LEGO approach presents a novel method to obtain flexible electronics in a lock-and-key (plug and play) manner with reliable interconnects. It includes a process to convert standard rigid IC into flexible LEGO without any performance degradation with a high-yield. For the majority of healthcare and environmental monitoring applications, a sensory array is essential for continuous spatiotemporal activity recording. Here we present an ultra- high-density sensory solution (1 million sensors) as an epitome of density and address each of the associated challenges. A generic heterogeneous integration scheme is devised to obtain a physically flexible standalone electronic system using 3D-coin architecture. Lastly, a feather-light non-invasive ‘Marine-Skin’ platform to monitor deep-ocean monitoring is presented using the heterogeneous integration scheme. Electrical and mechanical characterization establish the reliability, integrity, robustness, and ruggedness of the processes, sensors, and multisensory flexible system.

Abstract

Abstract text.

Physically compliant electronics are scientifically intriguing, mechanically complex, ‎technologically ‎challenging but with huge socio-economical potential. Until now the target applications ‎for ‎flexible electronics have been limited to displays, solar cells, printed batteries, wearables, and ‎implantable. However, with the emergence and growth of Internet of Things (IoT) devices ‎worldwide ‎from nearly 27 billion in 2017 to 125 billion in 2030, in this PhD research, expanding the ‎horizon of ‎applications for flexible electronics toward existing “things” will be explored. Low-cost sustainable materials as active electronic materials and a ‎Do-It-Yourself (DIY) integration strategy is used to build “Add-on” standalone sensory system which can be ‎attached to any ‎existing things like a decal. Such electronics can also be embedded in newly minted ‎devices specially ‎using additive methods.

Power constraint has become a critical challenge for computing, restricting the rate at which data can be processed. The physics of ordered and correlated systems allow for fundamental improvement of the energy efficiency in this regard, going beyond what is possible with conventional materials in today’s computing hardware. One such example is the the ferroelectric materials, where thermodynamics dictate that charge can be switched with much lower energy compared to conventional dielectrics. This leads to a situation where a ferroelectric material can be stabilized at a state of negative capacitance. In this talk, I shall discuss our experimental work demonstrating the stabilization of negative capacitance, its integration into advanced transistors, and its potential impact on next generation computing hardware.

In this seminar, I will present the first wafer-scale statistical analysis of memristive crossbar arrays made of 2D layered materials. By using chemical vapor deposited multilayer hexagonal boron nitride (h-BN) sheets, we have fabricated metal/h-BN/metal memristive crossbar arrays that exhibit high yield ~98%, and low device-to-device variability. The devices showed record electrical performance, including stable operation at ultra-low currents down to 110 fA in low resistive state, ON/OFF current ratios up to 1011, record non-linearity of <0.09 mV/decade, and unprecedented low energy consumption down to 4.4 zJ/transition. Furthermore, the miniaturization of metal/h-BN/metal memristors has been demonstrated by using nanodot (Ø < 50 nm) electrodes. These findings may accelerate the use of 2D materials for building wafer-scale and high-density electronic memories and artificial neural networks.