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The objective of this work is to develop an effective TCAD based hot-carrier degradation model in predicting the damage that a SiGe HBT undergoes as it is stressed across bias, time and temperature.

Dans le but d’améliorer les transistors bipolaires TBH SiGe, nous proposons d’étudier l’impact de la contrainte mécanique sur leurs performances. En effet, cette contrainte permet de libérer un degré de liberté supplémentaire pour améliorer les propriétés du transport grâce à un changement de la structure de bande d’énergie du semiconducteur. Ainsi, nous avons proposé de nouvelles architectures de composants basées sur l’ingénierie de la contrainte mécanique dans les semiconducteurs. Deux approches ont été utilisées dans cette étude pour générer la tension mécanique adéquate à l'intérieur du dispositif. La première approche consiste à appliquer une contrainte mécanique sur la base du transistor en utilisant une couche de SiGe extrinsèque. La seconde approche vise à appliquer une contrainte dans la région du collecteur en utilisant une couche contrainte. Les résultats obtenus montrent que cette méthode peut être une approche prometteuse pour améliorer les performances des TBH. / The Impact of strain engineering technology applied on Si BJT/SiGe HBT devices on the electrical properties and frequency response has been investigated. Strain technology can be used as an additional degree of freedom to enhance the carriers transport properties due to band structure changes and mobility enhancement. New concepts and novel device architectures that are based on strain engineering technology have been explored using TCAD modeling. Two approaches have been used in this study to generate the proper mechanical strain inside the device. The first approach was through introducing strain at the device’s base region using SiGe extrinsic stress layer. The second approach was through introducing strain at the device’s collector region using strain layers. The obtained results obviously show that strain engineering technology principle applied to BJT/HBT device can be a promising approach for further devices performance improvements.

SiGe HBTs are preferred for quantum computing (QC) readout circuits due to their high gain and speed as well as the integration with complementary metal-oxide-semiconductor (CMOS) technology. The device physics of SiGe HBTs at cryogenic temperatures (CT), like carrier scattering, carrier transport, high-injection effects were not systematically and physically investigated. Thus, a physical compact model for circuit simulation did not exist at the start of this thesis work. In this work, the measurement setup has been built for obtaining direct-current (DC) and small-signal characteristics from medium to high frequencies over a wide temperature range. The radio frequency (RF) power of network analyzer and integration time of source monitor units have been investigated to ensure the accuracy of the DC and small-signal measurement. The key electrical parameters of SiGe HBTs have been characterized. The temperature trend of the transfer current, base current, sheet resistance, depletion capacitance, and built-in voltage, zero-bias hole charge have been extensively demonstrated and physically analyzed. Based on the comprehensive investigation on the electrical parameters over a wide range of temperatures, the following work consists of two parts: (1) the existing analytical formulations for various electrical components have been compared for their validation, and (2) in case of evident discrepancies the physical origin has been analyzed and valid compact formulations have been derived. For the first part, different bandgap models have been compared and the Lin et al. model is used for both TCAD simulation and compact model due to its high accuracy over a wide temperature and easy normalization for compact model usage. Based on the normalized bandgap voltage model, the derived built-in voltage model has been verified utilizing measured value for three depletion regions, i.e., base-emitter, base-collector and collector-substrate junction. Because the temperature dependence of zero-bias depletion capacitance and hole charge is attributed to the built-in voltage, the temperature behaviors of capacitance and hole charge are well modeled by the existing formulations according to the comparison between calculation and measurement. For the second part, for various SiGe HBT components discrepancies between model and measurement have been identified and comprehensive studies have been conducted. Firstly, the measured sheet and contact resistances of various components reduce with decreasing temperatures and saturate as the temperature towards 0K, which cannot be modeled by a widely used single power-law model. A Matthiesen's rule based model, consisting of two scattering mechanisms with opposite temperature trend, agrees well with the measured values. Additionally, an extended power-law model with a linear term is deduced for backward compatibility and less parameters. Secondly, direct tunneling is supposed to be dominant for transfer current at cryogenic temperatures, and a comprehensive derivation of transfer tunneling current for SiGe HBT is demonstrated. Moreover, a pronounced downward bending effect in both base-emitter and base-collector currents becomes significant at high current density region with decreasing temperatures. A modified diode current model including high-injection effect is given. Additionally, the recombination current is relevant for base-collector current and has been considered in the model. Due to the different temperature trends of thermal conductivity of silicon from cryogenic to room temperature, the thermal resistance shows a bell-shape and a modified formulation has been derived. Moreover, the dependence on chuck temperature and power dissipation has been considered. Finally, the derived formulations have been implemented in the mainstream industry BJT/HBT compact model, HIgh CUrrent Model - Level 2 (HICUM/L2), and good agreement has been achieved with the measurement. / Silizium-Germanium (SiGe) Heterojunction-Bipolartransistoren (HBTs) werden aufgrund ihrer hohen Verstärkung und Geschwindigkeit sowie der Integration in die komplementäre Metall-Oxid-Halbleiter (CMOS)-Technologie für Ausleseschaltungen im Quantencomputer (QC) bevorzugt. Die Bauelemente Physik von SiGe-HBTs bei kryogenen Temperaturen (CT), wie z.B. Ladungsträgerstreuung, Ladungsträgertransport und Hochinjektionseffekte, wurde nicht systematisch und physikalisch untersucht. Daher gab es kein physikalisches Kompaktmodell für die Schaltungssimulation zu Beginn dieser Arbeit. In dieser Arbeit wurde der Messaufbau für Gleichstrom- und Kleinsignaleigenschaften von mittleren bis hohen Frequenzen über einen weiten Temperaturbereich aufgebaut. Die Radiofrequenz (RF)-Leistung des Netzwerkanalysators und die Integrationszeit der Source-Monitor-Einheiten wurden untersucht, um die Genauigkeit der Gleichstrom- und Kleinsignalmessung zu gewährleisten. Die wichtigsten elektrischen Parameter von SiGe HBTs wurden charakterisiert. Der Temperaturtrend des Transferstroms, des Basisstroms, der Schichtwiderstände, der Verarmungskapazitäten, der eingebauten Spannung und der Gleichgewicht-Lochladung wurde ausführlich demonstriert und physikalisch analysiert. Basierend auf der umfassenden Untersuchung der elektrischen Parameter über einen weiten Temperaturbereich besteht diese Arbeit aus zwei Teilen: (1) die bestehenden analytischen Formulierungen für verschiedene elektrische Komponenten wurden zu ihrer Validierung verglichen, und (2) im Falle von Abweichungen wurden die physikalischen Ursachen analysiert und gültige kompakte Formulierungen abgeleitet. Für den ersten Teil wurden verschiedene Bandgap-Modelle verglichen, wobei das Modell von Lin et al. für sowohl Technology Computer-Aided Design (TCAD) Simulation als auch das Kompaktmodell aufgrund seiner hohen Genauigkeit über einen großen Temperaturbereich und der einfachen Normierung im Kompaktmodell verwendet wurde. Auf der Grundlage des normaierten Bandlückenmodells wurde das abgeleitete eingebaute Spannungsmodell anhand von Messwerten für drei Verarmungsbereiche, d.h. Basis-Emitter-, Basis-Kollektor- und Kollektor-Substrat-Übergang, verifiziert. Da die Temperaturabhängigkeit der Verarmungskapazität und der Löcherladung auf die eingebaute Spannung zurückzuführen ist, wird das Temperaturverhalten der Kapazität und der Löcherladung gemäß dem Vergleich zwischen den Berechnungen und den Messungen durch die ausgearbeitete Formulierung gut modelliert. Im zweiten Teil wurden für verschiedene Komponenten des SiGe HBTs Abweichungen zwischen Modellen und Messungen identifiziert und umfassende Studien durchgeführt. Erstens nehmen die gemessenen Schicht- und Kontaktwiderstände verschiedener Komponenten mit abnehmender Temperatur ab und bleiben konstant mit der Temperatur in Richtung 0K, was nicht durch ein weit verbreitetes einfaches Power-Law-Modell modelliert werden kann. Ein auf der Matthiesenschen Regel basierendes Modell, das aus zwei Streumechanismen mit entgegengesetztem Temperaturtrend besteht, stimmt gut mit den gemessenen Werten überein. Zusätzlich wird ein erweitertes Power-Law-Modell mit einem linearen Term abgeleitet, um bei geriegerer Parameterzahl die Rückwärtskompatibilität zu gewährleisten. Zweitens wird angenommen, dass direktes Tunneln für den Transferstrom bei kryogenen Temperaturen dominant ist, und es wird eine umfassende Herleitung des Transfer-Tunnelstroms für SiGe HBTs. Drittens wird ein ausgeprägter Effekt sowohl bei den Basis-Emitter- als auch bei den Basis-Kollektor-Strömen im Bereich hoher Stromdichten mit abnehmender Temperatur signifikant. Es wird ein modifiziertes Diodenstrommodell angegeben, das den Hochinjektionseffekt berücksichtigt. Darüber hinaus ist der Rekombinationsstrom für den Basis-Kollektor-Strom von Bedeutung und wurde in dem Modell berücksichtigt. Viertens zeigt der Wärmewiderstand aufgrund des unterschiedlichen Temperaturverlaufs der Wärmeleitfähigkeit in Silizium von Tieftemperatur bis Raumtemperaturen eine Glockenkurve und es wurde eine modifizierte Formulierung abgeleitet. Außerdem wurde die Abhängigkeit von der Chuck-Temperatur und der Verlustleistung wurde berücksichtigt. Schließlich wurden die abgeleiteten Formulierungen in das branchenübliche Bipolartransistor (BJT)/HBT Kompaktmodell, HIgh CUrrent Model - Level 2 (HICUM/L2), implementiert, und es wurde eine gute Übereinstimmung mit der Messung erzielt. / 硅锗异质结双极晶体管(SiGe HBT)因其高增益、高速度以及与互补金属氧化物半导体(CMOS)技术的集成而成为量子计算(QC)读出电路的首选。极低温 (CT) 下 SiGe HBT 的器件物理特性，如载流子散射、载流子传输、高注入效应等，尚未得到系统的物理研究。因此，在本论文工作开始时，并不存在用于极低温下电路仿真的紧凑型物理模型。 在这项工作中，首先搭建立了极低温电学测量装置，用于在宽温度范围内获得直流(DC)和中高频率小信号特性。为确保直流和小信号测量的准确性，对矢网分析仪的射频功率和信号源测量单元(SMU)的积分时间进行了研究。对 SiGe HBT 的关键电气参数进行了表征。对传输电流、基极电流、薄膜电阻、耗尽电容、内建电压、零偏置空穴电荷的温度变化趋势进行了广泛的论证和物理分析。 基于对宽温度范围内电气参数的全面研究，以下工作由两部分组成：(1) 比较各种电气元件的现有解析公式，以验证其有效性；(2) 对于有明显差异的物理量分析其物理原因，并推导出有效的紧凑型。 在第一部分中，比较了不同的禁带温度模型，由于 Lin 等提出的模型在较宽温度范围内具有较高的精确度，而且易于归一化，因此被用于 TCAD 仿真和紧凑型模型。根据归一化禁带温度模型，利用三个耗尽区(即基极-发射极、基极-集电极和集电极-衬底交界处)的测量值验证了推导出的内建电压模型。由于零偏压耗尽电容和空穴电荷的温度依赖性归因于内建电压，因此根据计算和测量结果的比较，现有公式可以很好地模拟电容和空穴电荷的温度行为。 在第二部分中，针对各种 SiGe HBT 组分发现了模型与测量值之间的差异，并进行了全面研究。首先，测量到的各种组分的薄膜电阻和接触电阻随着温度的降低而减小，当温度接近 0K 时达到饱和，这无法用广泛使用的单一幂律模型来模拟。基于 Matthiesen 规则的模型由两种温度趋势相反的散射机制组成，与测量值非常吻合。此外，为了实现向前兼容和减少参数，还推导出一个带有线性项的扩展幂律模型。其次，在低温条件下，直接隧穿是传输电流的主导，因此对 SiGe HBT 的传输隧穿电流进行了全面推导。此外，随着温度的降低，在高电流密度区域，基极-发射极和基极-集电极电流都会出现明显的向下弯曲效应，由此包含高注入效应的修正二极管电流模型给出。此外，模型还考虑了与基极-集电极电流相关的复合电流。由于硅的热导率从低温到室温的温度变化趋势不同，热阻呈现钟形，因此得出了一个修正的公式。此外，还考虑了热阻受环境温度和功耗的相关性。 最后，推导的公式嵌入到工业界主流 BJT/HBT 紧凑型模型 HIgh CUrrent Model - Level 2 (HICUM/L2) 中，仿真结果与测量结果取得了良好的一致。

The advent of high-frequency silicon-based technologies has enabled the design of mixed-signal circuits that incorporate analog, RF, and digital circuit components to build cost-effective system-on-a-chip solutions. Emerging applications provide great incentive for continued scaling of transistor performance, requiring careful attention to mismatch, noise, and reliability concerns. If these mixed-signal technologies are to be employed within space-based electronic systems, they must also demonstrate reliability in radiation-rich environments. SiGe BiCMOS technology in particular is positioned as an excellent candidate to satisfy all of these requirements. The objective of this research is to develop predictive modeling tools that can be used to design new mixed-signal technologies and assess their reliability on Earth and in extreme environments. Ultimately, the goal is to illuminate the interaction of device- and circuit-level reliability mechanisms and establish best practices for modeling these effects in modern circuits. To support this objective, several specific areas have been targeted first, including a TCAD-based approach to identify performance-limiting regions in SiGe HBTs, measurement and modeling of carrier transport parameters that are essential for predictive TCAD, and measurement of device-level single-event transients to better understand the physical origins and implications for device design. These tasks provide the foundation for the bulk of this research, which addresses circuit-level reliability challenges through the application of novel mixed-mode TCAD techniques. All of the individual tasks are tied together by a guiding theme: to develop a holistic understanding of the challenges faced by emerging broadband technologies by coordinating results from material, device, and circuit studies.

Thesis--Auburn University, 2009. / Abstract. Vita. Includes bibliographic references (p.64-66).

The objective of the research presented in this dissertation is to explore the achievable dynamic range limits in high-performance RF front-ends designed using SiGe HBTs, with a focus on complementary (npn + pnp) SiGe technologies. The performance requirements of RF front-ends are high gain, high linearity, low dc power consumption, very low noise figure, and compactness. The research presented in this dissertation shows that all of these requirements can easily be met by using complementary SiGe HBTs. Thus, a strong case is made in favor of using SiGe technologies for designing high dynamic range RF front-ends. The contributions from this research are summarized as follows: 1. The first-ever comparison study and comprehensive analysis of small-signal linearity (IIP3) for npn and pnp SiGe HBTs on SOI. 2. A novel comparison of large-signal robustness of npn and pnp SiGe HBTs for use in high-performance RF front-ends. 3. A systematic and rigorous comparison of SiGe HBT compact models for high-fidelity distortion modeling. 4. The first-ever feasibility study of using weakly-saturated SiGe HBTs for use in severely power constrained RF front-ends. 5. A novel X-band Low Noise Amplifier (LNA) using weakly-saturated SiGe HBTs. 6. Design and comprehensive analysis of RF switches with enhanced large-signal linearity. 7. Development of novel methods to reduce crosstalk noise in mixed-signal circuits and the first-ever analysis of crosstalk noise across temperature. 8. Design of a very high-linearity cellular band quadrature modulator for use in base-station applications using first-generation complementary SiGe HBTs.

The objective of the proposed work is to study the behavior of SiGe HBTs at cryogenic temperatures and its relation to device scaling and optimization. Not only is cryogenic operation of these devices required by space missions, but characterizing their cryogenic behavior also helps to investigate the performance limits of SiGe HBTs and provides essential information for further device scaling. Technology computer aided design (TCAD) and sophisticated on-wafer DC and RF measurements are essential in this research. Drift-diffusion (DD) theory is used to investigate a novel negative differential resistance (NDR) effect and a collector current kink effect in first-generation SiGe HBTs at deep cryogenic temperatures. A theory of positive feedback due to the enhanced heterojunction barrier effect at deep cryogenic temperatures is proposed to explain such effects. Intricate design of the germanium and base doping profiles can greatly suppress both carrier freezeout and the heterojunction barrier effect, leading to a significant improvement in the DC and RF performance for NASA lunar missions. Furthermore, cooling is used as a tuning knob to better understand the performance limits of SiGe HBTs. The consequences of cooling SiGe HBTs are in many ways similar to those of combined vertical and lateral device scaling. A case study of low-temperature DC and RF performance of prototype fourth-generation SiGe HBTs is presented. This study summarizes the performance of all three prototypes of these fourth-generation SiGe HBTs within the temperature range of 4.5 to 300 K. Temperature dependence of a fourth-generation SiGe CML gate delay is also examined, leading to record performance of Si-based IC. This work helps to analyze the key optimization issues associated with device scaling to terahertz speeds at room temperature. As an alternative method, an fT -doubler technique is presented as an attempt to reach half-terahertz speeds. In addition, a roadmap for terahertz device scaling is given, and the potential relevant physics associated with future device scaling are examined. Subsequently, a novel superjunction collector design is proposed for higher breakdown voltages. Hydrodynamic models are used for the TCAD studies that complete this part of the work. Finally, Monte Carlo simulations are explored in the analysis of aggressively-scaled SiGe HBTs.

Šiuolaikiniai Si/SiGe, AlGaAs/GaAs bei InGaP/GaAs įvarialyčiai dvipoliai tranzistoriai (ĮDT) pasižymi dideliu informacijos perdavimo greičiu, dideliu signalo stiprinimu, žemu triukšmų lygiu ir mažu signalo iškraipymu. Disertaciniame darbe atlikti Si/SiGe ir InGaP/GaAs ĮDT aukštadažnių charakteristikų ir triukšmo tyrimai dažnių ruože nuo 1 iki 30 GHz naudojant ir voltamperines charakteristikas. Tranzistorių triukšmų modeliavimas atliktas atsižvelgiant į tranzistoriaus šratinio triukšmo šaltinių koreliaciją, smūginę jonizaciją, tranzistoriaus parametrų temperatūrines priklausomybes. Dvipolių tranzistorių analitinis modelis, išvestas naudojant π –tipo ekvivalentinę grandinę, buvo įdiegtas į dvipolių tranzistorių kompaktinį (sutelktų parametrų) modelį HICUM (angl. high current model). Ši kompaktinio modelio versija gali aprašyti bazės ir kolektoriaus srovių šratinio triukšmo šaltinių koreliaciją. Kambario temperatūroje smūginės jonizacijos sąlygotas SiGe ĮDT triukšmo parametrų kitimas buvo tirtas hidrodinaminiu, dreifo - difuzijos ir kompaktiniu HICUM modeliais, taikant Chynowetho smūginės jonizacijos dėsnį griūtinių srovių įvertinimui. SiGe ĮDT temperatūriniai voltamperinių, aukštadažnių ir triukšmo charakteristikų tyrimai atlikti plačiame aplinkos temperatūrų ruože 4 – 423 K. Tyrimai parodė, kad hidrodinaminis ir kompaktinis HICUM modeliai galioja tik 300 – 423K temperatūrų ruože. / Modern Si/SiGe, AlGaAs/GaAs and InGaP/GaAs heterojunction bipolar transistors (HBTs) exhibit high-speed and high-frequency operation, high gain, low noise and low signal distortion. This work deals with an investigation of DC, microwave and noise characteristics of Si/SiGe and InGaP/GaAs HBTs in the relevant frrequency range of 1-30 GHz. Noise simulation and modeling of HBTs have been performed including correlation of shot noise sources, impact ionization and temperature dependences. Analytical model for bipolar transistor, based on π- type equivalent circuit was derived and implemented in the bipolar transistor compact model HICUM. This compact model HICUM version includes correlation between base and collector current noise sources. The noise behavior resulting from impact ionization was investigated at room temperature for SiGe HBTs. Modeling was performed with a hydrodynamic model, drift - diffusion models and the compact model HICUM using a Chynoweth’s law for avalanche generation. DC, high frequency characteristics and noise of SiGe HBTs were investigated in a wide ambient temperature range 4 – 423 K Both hydrodynamic device simulation and compact model HICUM view agreement with experimental data only in the temperature range of 300 – 423K.

Modern Si/SiGe, AlGaAs/GaAs and InGaP/GaAs heterojunction bipolar transistors (HBTs) exhibit high-speed and high-frequency operation, high gain, low noise and low signal distortion. This work deals with an investigation of DC, microwave and noise characteristics of Si/SiGe and InGaP/GaAs HBTs in the relevant frrequency range of 1-30 GHz. Noise simulation and modeling of HBTs have been performed including correlation of shot noise sources, impact ionization and temperature dependences. Analytical model for bipolar transistor, based on π- type equivalent circuit was derived and implemented in the bipolar transistor compact model HICUM. This compact model HICUM version includes correlation between base and collector current noise sources. The noise behavior resulting from impact ionization was investigated at room temperature for SiGe HBTs. Modeling was performed with a hydrodynamic model, drift - diffusion models and the compact model HICUM using a Chynoweth’s law for avalanche generation. DC, high frequency characteristics and noise of SiGe HBTs were investigated in a wide ambient temperature range 4 – 423 K Both hydrodynamic device simulation and compact model HICUM view agreement with experimental data only in the temperature range of 300 – 423K. / Šiuolaikiniai Si/SiGe, AlGaAs/GaAs bei InGaP/GaAs įvarialyčiai dvipoliai tranzistoriai (ĮDT) pasižymi dideliu informacijos perdavimo greičiu, dideliu signalo stiprinimu, žemu triukšmų lygiu ir mažu signalo iškraipymu. Disertaciniame darbe atlikti Si/SiGe ir InGaP/GaAs ĮDT aukštadažnių charakteristikų ir triukšmo tyrimai dažnių ruože nuo 1 iki 30 GHz naudojant ir voltamperines charakteristikas. Tranzistorių triukšmų modeliavimas atliktas atsižvelgiant į tranzistoriaus šratinio triukšmo šaltinių koreliaciją, smūginę jonizaciją, tranzistoriaus parametrų temperatūrines priklausomybes. Dvipolių tranzistorių analitinis modelis, išvestas naudojant π –tipo ekvivalentinę grandinę, buvo įdiegtas į dvipolių tranzistorių kompaktinį (sutelktų parametrų) modelį HICUM (angl. high current model). Ši kompaktinio modelio versija gali aprašyti bazės ir kolektoriaus srovių šratinio triukšmo šaltinių koreliaciją. Kambario temperatūroje smūginės jonizacijos sąlygotas SiGe ĮDT triukšmo parametrų kitimas buvo tirtas hidrodinaminiu, dreifo - difuzijos ir kompaktiniu HICUM modeliais, taikant Chynowetho smūginės jonizacijos dėsnį griūtinių srovių įvertinimui. SiGe ĮDT temperatūriniai voltamperinių, aukštadažnių ir triukšmo charakteristikų tyrimai atlikti plačiame aplinkos temperatūrų ruože 4 – 423 K. Tyrimai parodė, kad hidrodinaminis ir kompaktinis HICUM modeliai galioja tik 300 – 423K temperatūrų ruože.