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Journal ArticleDOI

A Pragmatic Approach to Modeling Self-Heating Effects in SiGe HBTs

30 Oct 2017-IEEE Transactions on Electron Devices (IEEE)-Vol. 64, Iss: 12, pp 4844-4849
TL;DR: In this paper, an accurate closed-form analytical model is proposed to predict the junction temperature and thermal resistance of silicon germanium heterojunction bipolar transistors, including the effect of back-end-of-line (BEOL) metal layers.
Abstract: An accurate closed-form analytical model is proposed to predict the junction temperature and thermal resistance of silicon germanium heterojunction bipolar transistors, including the effect of back-end-of-line (BEOL) metal layers. A linear approximation is used in a thermal resistivity model of silicon to reduce the model complexity. A simple method is proposed to extract the necessary model parameters along with the BEOL thermal resistance. The model is validated with the TCAD simulation, and the scalability of the model is verified by the comparison with experimental data for different device geometries. The model shows excellent agreement with both TCAD simulation (without BEOL) and experimental data (with BEOL).
Citations
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Journal ArticleDOI
TL;DR: In this article, the reliability issues of SiGe HBTs were investigated by combining dedicated experiments and TCAD simulations, and the authors showed the important role played by the back-end-of-line (BEOL) and substrate thermal resistance in dissipating the heat generated by impact ionization.
Abstract: Recently, a wide class of market segments (e.g., health, material science, security, and communications) is tackled by circuits fabricated in BiCMOS technology, integrating silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs) and passives. Currently, the reliability of SiGe HBT devices is a major concern, and much attention is given to self-heating (SH), that limits device performance and regulates their degradation during stress. Moreover, its relevance is supposed to increase with device scaling. In this paper, we explore the reliability issues of SiGe HBTs by combining dedicated experiments and TCAD simulations. We develop and calibrate a TCAD model that is then used to investigate SH effects in both operating and stress conditions. Results show the important role played by the back-end-of-line (BEOL) and by the substrate thermal resistance in dissipating the heat generated by impact ionization. The location at which defects are generated during stress and the microscopic properties of the defects are determined experimentally by means of dedicated noise measurements. Including defects in the TCAD model allows reproducing the degradation observed in stress experiments. Simulations of the SH effects on a stressed device in measurement conditions revealed the presence of a hole hot spot that suggests a possible physical mechanism involved in the degradation slowdown at long stress times reported in the literature.

6 citations

Journal ArticleDOI
TL;DR: In this article, the authors proposed a step-by-step strategy to model the static thermal coupling factors between the fingers in a silicon-based multifinger bipolar transistor structure, which takes as inputs the dimensions of emitter fingers, shallow and deep trench isolations, their relative locations and the temperature dependent material thermal conductivity.
Abstract: In this part, we propose a step-by-step strategy to model the static thermal coupling factors between the fingers in a silicon based multifinger bipolar transistor structure. First we provide a physics-based formulation to find out the coupling factors in a multifinger structure having no-trench isolation (cij,nt). As a second step, using the value of cij,nt, we propose a formulation to estimate the coupling factor in a multifinger structure having only shallow trench isolations (cij,st). Finally, the coupling factor model for a deep and shallow trench isolated multifinger device (cij,dt) is presented. The proposed modeling technique takes as inputs the dimensions of emitter fingers, shallow and deep trench isolations, their relative locations and the temperature dependent material thermal conductivity. Coupling coefficients obtained from the model are validated against 3D TCAD simulations of multifinger bipolar transistors with and without trench isolations. Geometry scalability of the model is also demonstrated.

5 citations


Cites background or methods from "A Pragmatic Approach to Modeling Se..."

  • ...Following the findings of [23] that the thermal resistivity 1/κ(T) of Si linearly varies with T, a similar but pragmatic model for self-heating resistance is derived in [12] by putting κc = 0....

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  • ...and [ 1 κ(T) ] avg signifies average thermal resistivity as done in [12] and is obtained from the temperature dependent thermal conductivity relation of Si as κ(T) = (κa + κbT + κcT2)−1 [8]....

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  • ...The model accuracy and associated parameter extraction are also reported in [12]....

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Journal ArticleDOI
TL;DR: This work presents a simple analytical model for electrothermal heating in multifinger bipolar transistors under realistic operating condition where all fingers are heating simultaneously and simulates 40% faster than the conventional model in a transient simulation of a five-finger transistor.
Abstract: In this work, we present a simple analytical model for electrothermal heating in multifinger bipolar transistors under realistic operating condition where all fingers are heating simultaneously. The proposed model intuitively incorporates the effect of thermal coupling among the neighboring fingers in the framework of self-heating bringing down the overall model complexity. Compared to the traditional thermal modeling approach for an ${n}$ -finger transistor where the number of circuit nodes increases as ${n}^{{2}}$ , our model requires only ${n}$ -number of nodes. The proposed model is scalable for any number of fingers and with different emitter geometries. The model is validated with 3-D thermal simulations and measured data from STMicroelectronics B4T technology. The Verilog-A implemented model simulates 40% faster than the conventional model in a transient simulation of a five-finger transistor.

3 citations


Cites background from "A Pragmatic Approach to Modeling Se..."

  • ...fG (z) signifies the position-dependent geometry factor of the heat spread [13]....

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Journal ArticleDOI
TL;DR: In this article , the thermal resistance of heterojunction bipolar transistors (HBTs) has been evaluated and discussed using a detailed evaluation and discussion of several widely used methods.
Abstract: Many different methods have been proposed in the literature for the extraction of the thermal resistance of heterojunction bipolar transistors (HBTs). This review presents a detailed evaluation and discussion of several widely used methods. Special emphasis is put on a generalized analysis of the underlying assumptions, suitable operating point range, and necessary measurement effort of each method. The accuracy of each method is determined by applying it to data based on circuit simulations of advanced SiGe and III-V HBT technologies. Experimental data from those technologies are used to highlight practical issues. A guideline for the selection of the most suitable method in practice is also given.

3 citations

Journal ArticleDOI

2 citations


Additional excerpts

  • ...A 1⁄4 1 GTH1 −M − 1 GTH2 −M Tj1 − Tj2 : (14)...

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References
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Journal ArticleDOI
P.D. Maycock1
TL;DR: In this paper, the thermal conductivities of mixed III-V compounds: indium arsenide-phosphide, gallium-indium arsenides and gallium antimonides are presented.
Abstract: The thermal conductivities as a function of temperature for silicon, germanium, gallium arsenide, indium phosphide, indium arsenide, indium antimonide, gallium phosphide, aluminum antimonide and gallium antimonide are presented. Also included are the thermal conductivities of the mixed III–V compounds: indium arsenide-phosphide, gallium-indium arsenide and gallium arsenide-phosphide. These data are derived from the publications listed in the bibliography and represent the author's selection of the “most probable” values. A brief phenomenological discussion of the mechanisms involved in thermal conduction is presented.

265 citations


"A Pragmatic Approach to Modeling Se..." refers background in this paper

  • ...For a typical range of Tj from 300 to 500 K, the change in thermal conductivity of Cu is known to be significantly less compared to that of Si [15]....

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Journal ArticleDOI
TL;DR: In this paper, a detailed review of a full SiGe HBT BiCMOS process is presented, with a description of a 12-bit Digital-to-Analog Converter.
Abstract: For pt. I, see ibid., vol. 3, p. 455-68 (1995). This part focuses on process integration concerns, first described in general terms and then detailed through an extensive review of both simple non-self-aligned device structures and more complex self-aligned device structures. The extension of SiGe device technology to high levels of integration is then discussed through a detailed review of a full SiGe HBT BiCMOS process. Finally, analog circuit design is discussed and concluded, with a description of a 12-bit Digital-to-Analog Converter presented to highlight the current status of SiGe technology. >

240 citations


"A Pragmatic Approach to Modeling Se..." refers background in this paper

  • ...H IGH-FREQUENCY capabilities of the modern silicon germanium heterojunction bipolar transistor (SiGe HBT) structures, aided by aggressive scaling and use of trench isolations, come with high operating current densities leading to a serious self-heating problem [1]–[4]....

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Journal ArticleDOI
TL;DR: In this article, the emitter ballasting resistor for power heterojunction bipolar transistors (HBTs) was investigated and the current handling capability of power HBTs was found to improve with ballasting resistance.
Abstract: A systematic investigation of the emitter ballasting resistor for power heterojunction bipolar transistors (HBTs) is presented. The current handling capability of power HBTs is found to improve with ballasting resistance. An equation for the optimal ballasting resistance is presented, where the effects of thermal conductivity of the substrate material and the temperature coefficient of the ballasting resistor are taken into account. Current levels of 400 to 800 mA/mm of emitter periphery at case temperatures of 25 to -80 degrees C for power AlGaAs/GaAs HBTs have been obtained using an on-chip lightly doped GaAs emitter ballasting resistor. Device temperature has been measured using both an infrared microradiometer and temperature-sensitive electrical parameters. Steady-state and transient thermal modeling are also performed. Although the measured temperature is spatially nonuniform, the modeling results show that such nonuniformities would occur for a uniform current distribution, as would be expected for an HBT with emitter ballasting resistors. >

122 citations


"A Pragmatic Approach to Modeling Se..." refers background in this paper

  • ...In [7], it is nonphysically and inaccurately treated as temperatureindependent to obtain a closed-form solution as RTHs = fG/κ(Tamb), where fG denotes the integral ∫ h 0 dz/ζ(x, y, z) and is also known as the geometry factor [8]....

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Book
25 Nov 2010
TL;DR: This book begins with an overview on the different device designs of modern bipolar transistors, along with their relevant operating conditions; while the subsequent chapter on transistor theory is subdivided into a review of mostly classical theories, brought into context with modern technology.
Abstract: "Compact Hierarchical Bipolar Transistor Modeling with HICUM" will be of great practical benefit to professionals from the process development, modeling and circuit design community who are interested in the application of bipolar transistors, which include the SiGe:C HBTs fabricated with existing cutting-edge process technology. This book begins with an overview on the different device designs of modern bipolar transistors, along with their relevant operating conditions; while the subsequent chapter on transistor theory is subdivided into a review of mostly classical theories, brought into context with modern technology, and a chapter on advanced theory that is required for understanding modern device designs. This book aims to provide a solid basis for the understanding of modern compact models.

116 citations

Proceedings ArticleDOI
10 Dec 2002
TL;DR: In this paper, the effect of the structural variation of device on its thermal resistance was investigated for trench-isolated bipolar transistors, and an analytical thermal model was also developed and provided a good prediction on the structural dependence of the thermal resistance.
Abstract: The effect of the structural variation of device on its thermal resistance was investigated for trench-isolated bipolar transistors. Devices with various number of emitter segments and inter-segment spacings and several different trench-to-emitter distances were fabricated and the thermal resistance was measured/compared. An analytical thermal model was also developed and provided a good prediction on the structural dependence of the thermal resistance, exhibiting a good agreement with the measurement. 2D thermal device simulation was performed to obtain detailed temperature distribution inside the devices.

66 citations


"A Pragmatic Approach to Modeling Se..." refers background in this paper

  • ...In [7], it is nonphysically and inaccurately treated as temperatureindependent to obtain a closed-form solution as RTHs = fG/κ(Tamb), where fG denotes the integral ∫ h 0 dz/ζ(x, y, z) and is also known as the geometry factor [8]....

    [...]