Advanced numerical investigation of the heat flux in an array of microbolometers

The investigation of the thermal properties of an array of microbolometers has been carried out by mean of two independent numerical analysis, respectively the Direct-Simulation Monte Carlo (DSMC) and the classic diffusive approach of the Fourier's equation. In particular, the thermal dissipation of a hot membrane placed in a low-pressure cavity has been studied for different values of the temperature of the hot body and for different values of the pressure of the environment. The results for the heat flux derived from the two approaches have then been compared and discussed

Physical device modeling of Si/Si1-xGex multi-quantum well detector to optimize Ge content for higher thermal sensitivity

This paper presents the physical device modeling of a Si/Si1-xGex multi-quantum well (MQW) detector to optimize the Ge content in the Si/Si1-xGex well required to enhance thermal sensitivity for a potential microbolometer application. The modeling approach comprises a self-consistent coupled Poisson-Schroedinger solution in series with the thermionic emission theory at the Si/Si1-xGex heterointerface and quantum confinement within the Si/Si1-xGex MQW. The integrated simulation environment developed in Sentauruas WorkBench (SWB) TCAD is employed to investigate the transfer characteristics of the device consisting three stacks of Si/Si1-xGex wells with an active area of 17μm x 17μm were investigated and compared with experiment data

Gain enhancement of BiCMOS on-chip sub-THz antennas by mean of meta-cells

A MM-loaded sub-THz on-chip antenna with a narrow beamwidth, 9 dB gain and a simulated peak efficiency of 76% at the center frequency of 300 GHz is presented. By surrounding the antenna with a single MM-cell ring defined solely on the top metal of the back-end of line, an efficient suppression of the surface waves is obtained. The on-chip antenna has been designed using IHPs 130 nm SiGe BiCMOS technology with a 7-layer metallization stack, combined with the local backside etching process aimed to creating an air cavity which is then terminated by a reflective plane. By comparing the measured MM-loaded antenna performances to its non-MM-loaded counterpart, an enhanced integrity of the main lobe due to the MM-cells shielding effect can be observed. An excellent agreement between the simulated and measured performances has been found, which makes the MM-loaded antennas a valid alternative for the upcoming next-generation sub-THz transceivers

Development and mechanical modeling of Si1-XGex/Si MQW based uncooled microbolometers in a 130 nm BiCMOS

This paper presents the development of process integration and mechanical modeling of a Si1-xGex/Si MQW based uncooled micro-bolometer. The recent progress on layer transfer based integration scheme of Si1-xGex/Si based micro-bolometer into a 130 nm BiCMOS process is presented. The two important parts of the process integration, namely the layer-transfer and stress compensation of the arms are studied. The initial successful results on layer transfer and the FEM modeling for the stress compensation of the thin and narrow arms of the bolometer is presented. Finally, the developed FEM model is compared with the fabricated cantilevers. The results show that the developed FEM model has a very good matching with the experimental results; thus very convenient to use for the FEM modeling of the full bolometer structure

Charakterisierung von Perowskit-ähnlichen, high-k dielektrischen Materialien für Metall-Isolator-Metall Kondensatoren

MIM-Kondensatoren sind eine wichtige Schlüsselkomponente in integrierten Analog/ Mixed-Signal Hochfrequenz-Schaltkreisen. Entsprechend der International Technology Roadmap for Semiconductors sollen MIM-Kondensatoren für zukünftige Hochfrequenzanwendungen hohe Kapazitätsdichten bei geringen Leckstromdichten, geringe Spannungsabhängigkeiten sowie hohe Gütefaktoren aufweisen. Aufgrund der begrenzten Kapazitätsdichte und Zuverlässigkeit von SiO2 and Si3N4 erscheint es nicht möglich diesen Anforderungen mit konventionellen Dielektrika gerecht zu werden. Deshalb besteht die zwingende Notwendigkeit konventionelle Dielektrika durch high k Dielektrika zu ersetzen. In dieser Dissertation liegt der Fokus auf der Untersuchung von verschiedenen alternativen Dielektrika unter Verwendung ein- und mehrlagiger Dielektrikumsstrukturen für zukünftige MIM-Kondensator Applikationen. Es werden Einflüsse von nachfolgenden Ausheilungsprozessen und verschiedenen Elektrodenmaterialien auf die Eigenschaften der MIM- Kondensatoren untersucht. Dabei soll speziell die Charakterisierung von MIM-Kondensatoren in Bezug auf physikalischen und elektrischen Eigenschaften Beachtung geschenkt werden.Metal-Insulator-Metal (MIM) capacitors are one of the key building blocks in radio frequency analog/mixed signal integrated circuits. According to International Technology Roadmap for Semiconductors requirements, MIM capacitors should exhibit high capacitance densities accompanied with low leakage current density, small voltage dependency and high quality factor for future applications. However, based on conventional dielectric materials, like SiO2 and Si3N4, it is not possible to meet these requirements mainly due to limited capacitance density values and reliability issues. Therefore, there is urgent need to replace the conventional dielectric material with high dielectric constant materials as this is the most promising solution. In this thesis, the focus is on screening of different alternative dielectric materials using single or multilayer dielectric structures for future MIM capacitor applications. Moreover, influences of post-deposition annealing and electrode materials on MIM capacitor properties are investigated. Special attention is given on the characterization of MIM capacitors in terms of physical and main electrical properties

Comprehensive predictive device modeling and analysis of a Si/Si1−xGex multiquantum-well detector

This paper presents a predictive device model implemented by a self-consistent solution of Poisson-Schrödinger drift-diffusion formulation for a thermally sensitive detector based on a Si/Si₁₋ₓGeₓ multiquantum-well structure. The physical phenomena governing the carrier transport were modeled to investigate the effect of physical design aspects (Ge content, well periodicity, and well thickness). In particular, we have analyzed the effect of these physical design parameters on the carrier dynamics quantified by the dc performance in terms of net current density. A fully integrated simulation framework was developed and employed to optimize Ge content and device doping for a desired figure of merits specified by temperature coefficient of resistance (TCR) and dc resistance ( R ). This methodology was successfully utilized to realize device profiles for various amounts of Ge content and optimization of ( R ) geared for both high TCR and low noise. The dc performance metrics of the optimized profiles obtained by modeling presented here are compared and validated with the fabricated test devices

A behavioral model for high Ge content in Si/Si1-xGex multi-quantum well detector

This paper presents a behavioral model for a Si/Si1-xGex multi-quantum well (MQW) detector that predicts device characteristics to investigate the effect of increasing Ge content in Si/Si1-xGex MQW. The modeling approach in this work is based on a physical instead of empirical approach which allows to obtain a predictive behavioral analysis of high Ge content with only a few fitting parameters. The model is used to simulate device transfer characteristics with respect to various amounts of Ge content used for Si1-xGex layer in MQW. The simulation results of the proposed model are validated with the experimental data. The simulated and the experimental data are consistent over a wide range of Ge content varied from 30% up to 50%. The primary objective of this work is to optimize Ge content in Si/Si1-xGex MQW detector to achieve desired thermal sensitivity measured in terms of temperature coefficient of resistance (TCR) for a potential microbolometer application. This is the first study in the literature to develop such a highly predictive behavioral model of a Ge-enriched Si/Si1-xGex MQW. The study also presents the effect of including the carbon delta (C-delta) layers at the Si/Si1-xGex heterointerface on the device transfer characteristics. The effect of Ge content on the overall noise is also investigated by the noise characterization of the test devices

A test platform for the noise characterization of SiGe microbolometer ROICs

This paper introduces an in-circuit performance evaluation system for SiGe microbolometer readout integrated circuits (ROICs) that can characterize the overall system noise performance by emulating microbolometers with MOSFETs biased in the triode region. Specifically, the proposed test platform is designed for the testing of imagers with high resistance SiGe microbolometers. The architecture of the ROIC is based on a bridge with active and reference bolometer pixels with a capacitive transimpedance amplifier input stage and column parallel integration with serial readout. Noise measurements along with simulated resistance curves of the dummy detectors are reported. The prototype with 17-mu m pixel pitch has been designed and fabricated in a 0.25-mu m SiGe BiCMOS process