This paper presents Si/SiGe:C and InP/GaAsSb HBTs which feature specific assets to address submillimeter-wave and THz applications. Process and modeling status and challenges are reviewed. The specific topics of thermal and substrate effects, reliability, and HF measurements are also discussed.

Si/SiGe:C and InP/GaAsSb Heterojunction Bipolar Transistors for THz Applications

Fabrication and circuit design are linked by compact device modeling; i.e., the electrical characteristics of the devices fabricated on a wafer are represented by sufficiently simple but preferably still physics-based models that are suitable for circuit simulation and optimization. The importance of modeling has been growing rapidly due to strongly increased device complexity, manufacturing cost, and fabrication time. There is an increased demand from industry for first-pass success of high-frequency (HF) analog circuits in order to stay competitive. For SiGeC HBT technologies, ranging from production to the most advanced process, this has been successfully addressed by the standard compact bipolar transistor model HICUM/L2 [Schr10]. For practical applications, a compact model (CM) itself is not sufficient though. Its model parameters need to be determined from measurements of terminal (current, voltage) characteristics, preferably making use of clever test structures and mathematical manipulations (so-called parameter extraction methods) in order to be able to separate the various, often superimposed, physical effects and their related parameters. Consistent physics-based parameter extraction methods that provide for a given process accurate geometry-scalable and statistical device models not only represent a key enabler to first-pass design success but also yield important information for process development. One objective of DOTSEVEN was the development of

Silicon-Germanium Heterojunction Bipolar Transistors for mm-Wave Systems: Technology, Modeling and Circuit Applications

A strategy for compact modeling the static thermal coupling between the emitter fingers of SiGe heterojunction bipolar transistors (SiGe-HBTs) is described. An extraction methodology that includes the nonlinear temperature dependence of the thermal conductivity is introduced and applied to suitable test structures. The experimental results are used for calibrating a 3-D numerical solution of the equation for heat conduction based on a Green's function approach. The latter can then be employed for generating thermal coupling networks for arbitrary transistor configurations.

Characterization of the Static Thermal Coupling Between Emitter Fingers of Bipolar Transistors

This paper studies the mutual thermal coupling in trench isolated SiGe:C HBTs featuring peak fT and peak fmax of ~300GHz and ~400GHz, respectively. Inter- and intra-device thermal coupling parameters are extracted on specially designed test structures consisting of a five-finger HBT and a five-transistor array. The obtained coupling parameters are implemented in a distributed transistor model that considers self-heating as well as thermal coupling between devices. Very good agreement is achieved between circuit simulations and measurements.

Mutual thermal coupling in SiGe:C HBTs

An overview on the compact modeling activities within the DOTSEVEN project is given. Issues such as geometry scaling, substrate coupling and thermal effects as well as HICUM Level 2 features enabling the accurate modeling of the linear and non-linear characteristics of the latest generation of SiGe HBTs are discussed. Furthermore, experimental results for the most important DC and small-signal characteristics as well as selected examples for non-linear modeling of the most advanced SiGe HBTs from two different technologies are presented. Model verification issues related to limited on-wafer high-frequency measurement capability and the accurate calibration at multi-hundred GHz are briefly touched.

http://ieeexplore.ieee.org/iel7/7329075/7340543/07340560.pdf

SiGe HBT modeling for mm-wave circuit design

The suitability of the compact model HICUM for a state-of-the-art Silicon-Germanium (SiGe) heterojunction bipolar transistor (HBT) technology is evaluated with special emphasis on an efficient scalable modeling methodology. Multifinger HBTs particularly applicable to power applications are modeled. For modeling the critical self-heating effect a distributed thermal network is applied, yielding only a small impact on modeling results though. DC, AC, and large-signal distortion characteristics show good agreement between measurements and results from compact model simulation, demonstrating the capability of the modeling approach.

/pdf/scalable-compact-modeling-for-sige-hbts-suitable-for-4hmcnqy3yg.pdf

Scalable compact modeling for SiGe HBTs suitable for microwave radar applications

Highlights from Silicon Device Physics, material sciences and electrical engineering are among the first results to be presented from GFs subcontracts in the IPCEI-project, namely a reconfigurable FET compatible with 22-FDX-technology, a CMOS compatible new material Si doped HfO 2 for electrocaloric/ pyroelectric effects on chip, modelling of the 22FDX devices in the higher GHz range and first 5G Dual Band transceiver blocks designed in 22FDX

IPCEI subcontracts contributing to 22-FDX Add-On Functionalities at GF

Accurate thermal models for power devices are crucial due to the simultaneous introduction of deep trenches (DTI) and silicon on insulator (SOI) technology. A computationally efficient geometry dependent thermal model is presented that avoids the time and cost penalty of numerical thermal simulations and utilizes the Green's function approach in combination with mixed boundary conditions. The derived model is accurate (relative temperature error &#60; 10%) and valid for dimensions ranging between 5µm and 200µm. The new model allows for on-the-fly calculations of the thermal resistance R th as well as thermal coupling coefficients for multi-finger devices, enabling predictive modeling and concurrent engineering.

Thermal modeling of BOX/DTI enclosed power devices with Green's function approach

Electro-thermal characterization of SiGe HBTs was performed for different operating points. Small-signal simulations with a single-pole and various multi-pole thermal networks are compared with measured data over a wide frequency range. The results show that nodal and recursive thermal networks are unable to match the measured phase of the thermal impedance Zth, while Foster, Cauer and Cauer-type recursive thermal networks are more accurate and flexible for modeling Zth. Furthermore, a guide for the usage of different networks upon the phase of Zth is provided.

Yves Zimmermann

Papers

Characterization of the Static Thermal Coupling Between Emitter Fingers of Bipolar Transistors

Scalable compact modeling for SiGe HBTs suitable for microwave radar applications

IPCEI subcontracts contributing to 22-FDX Add-On Functionalities at GF

Thermal modeling of BOX/DTI enclosed power devices with Green's function approach

Thermal impedance of SiGe HBTs: Characterization and modeling