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A summary of total dose effects observe in advanced Silicon Germanium (SiGe) Heterojunction Bipolar Transistors (HBTs) is presented in this work. The principal driving froces behin the increased use of SiGe BiCMOS technology in space based electronics systems are outlined in the motivation Section of Chapter I. This is followed by a discussion of the strained layer Si/SiGe material structure and relevant fabrication techniques used in the development of the first generation of this technology. A comprehensive description of the device performance is presented. Chapter II presents an overview of radiation physics as it applies to microelectronic devices. Several sources of radiation are discussed including the environments encountered by satellites in different orbital paths around the earth. The particle types, interaction mechanisms and damage nomenclature are described. Proton irradiation experiments to analyze worst case displacement and ionization damage are examined in chapter III. A description of the test conditions is first presented, followed by the experimental results on the observed dc and ac transistor performance metrics with incident radiation. The impact of the collector doping level on the degradation is discussed. In a similar fashion, gamma irradiation experiments to focus on ionization only effects are presented in chapter IV. The experimental design and dc results are first presented, followed by a comparison of degradation under proton irradiation. Additional proton dose rate experiments conducted to further investigate observed differences between proton and gamma results are presented.

The objective of this thesis is to design RF circuits using silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) for communication system. The packaging effect for the SiGe chip using liquid crystal polymer (LCP) is presented and methodology to derive the model for the package is discussed. Chapter 1, we discuss the overview and benefits of SiGe HBT technology in high frequency circuit design. Chapter 2 presents the methodology of the low noise amplifier (LNA) design and discusses the trade-off between the noise and gain matching. The technique for achieving simultaneous noise and gain matching for the LNA is also presented. Chapter 3 presents an L-band cascaded feedback SiGe low noise amplifier (LNA) design for use in Global Position System (GPS) receivers. Implemented in a 200 GHz SiGe BiCMOS technology, the LNA occupies 1 x 1 millimeter square (including the bondpads). The SiGe LNA exhibits a gain greater than 23 dB from 1.1 to 2.0 GHz, and a noise figure of 2.7 to 3.3 dB from 1.2 to 2.4 GHz. At 1.575 GHz, the 1-dB compression point (P1dB) is 1.73 dBm, with an input third-order intercept point (IIP3) of -3.98 dBm. Lastly, Chapter 4 covers the packaging techniques for the SiGe monolithic integrated circuit (MMIC). We present the modeling of a liquid crystal polymer (LCP) package for use with an X-band SiGe HBT Low Noise Amplifier (LNA). The package consists of a 2 mil LCP laminated over an embedded SiGe LNA, with vias in the LCP serving as interconnects to the LNA bondpads. An accurate model for the packaging interconnects has been developed and verified by comparing to measurement results, and can be used in chip/package co-design.

The objective of this work is to investigate the performance of SiGe HBTs and scaled CMOS devices in extreme environments. In this work, the inverse mode operation of SiGe HBTs is investigated as a potential solution to the vulnerability of SiGe HBTs to single event effects. The performance limitations of SiGe HBTs operating in inverse mode are investigated through an examination of the effects of scaling on inverse mode performance and optimization schemes for inverse mode performance enhancements are discussed and demonstrated. In addition the performance of scaled MOSFETs, that constitute the digital backbone of any BiCMOS technology, is investigated under radiation exposure and cryogenic temperatures. Extreme environments and their effects on semiconductor devices are introduced in Chapter 1. The immunity of 90nm MOSFETs to total ionizing dose damage under proton radiation is demonstrated. Inverse mode operation of SiGe HBTs is introduced in Chapter 2 as a potential radiation hard solution by design. The effect of scaling on inverse mode performance of SiGe HBTs is investigated and the performance limitations in inverse mode are identified. Optimization schemes for improving inverse mode performance of SiGe HBTs are discussed in Chapter 3. Inverse mode performance enhancement is demonstrated experimentally in optimized device structures manufactured in a commercial third generation SiGe HBT BiCMOS platform. Further, a cascode device structure, the combines the radiation immunity of an inverse mode structure with the performance of a forward mode common emitter device is XIV discussed. Finally, idealized doping profiles for inverse mode performance enhancement is discussed through TCAD simulations. The cryogenic performance of inverse mode SiGe HBTs are discussed in Chapter 4. A novel base current behavior at cryogenic temperature is identified and its effect on the inverse mode performance is discussed. Matching performance of a 90nm bulk CMOS technology at cryogenic temperatures is investigated experimentally and through TCAD simulations in Chapter 5. The effect of various process parameters on the temperature sensitivity of threshold voltage mismatch is discussed. The potential increase of mismatch in subthreshold MOSFETs operating in cryogenic temperatures due to hot carrier effects is also investigated.

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Cressler, John; Committee Member: Deo, Chaitanya; Committee Member: Doolittle, Alan; Committee Member: Keezer, David; Committee Member: May, Gary; Committee Member: Papapolymerou, John. Part of the SMARTech Electronic Thesis and Dissertation Collection.

The objective of the proposed research is to characterize the safe-operating-area of silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) under radiofrequency (RF) operation and extreme environments. The degradation of SiGe HBTs due to mixed-mode DC and RF stress has been modeled for the first time. State-of-the-art 200 GHz SiGe HBTs were first characterized, and then DC and RF stressed. Excess base leakage current was modeled as a function of the stress current and voltage. This physics-based stress model was then designed as a sub-circuit in Cadence, and incorporated into SiGe power amplifier design to predict the DC and RF stress-induced excess base current. Based on these studies, characterization of RF safe-operating-area for SiGe HBTs using devices and circuits is proposed.