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Determination of self-heating in bipolar and heterojunction bipolar transistors by measurement and simulation Reid, Adam Robert
Abstract
Self-heating in bipolar transistors, the effect which causes a rise in the device junction temperature due to the electrical power dissipation, is of interest for several reasons, including device reliability, model parameter extraction and electrothermal modeling. Self-heating is most commonly quantified by a thermal resistance, which relates the device steady-state temperature and power dissipation. In this work we present an improved setup for measuring thermal resistance, based on an isothermal characterization of the device by means of a pulsed-bias experiment. A 30 times increase in bias-pulse speed, compared to previous setups, allows for the first time, accurate measurements to be made on devices with submicron emitter dimensions. Simultaneous to increased performance, we have achieved a significant reduction in the complexity of the setup through the elimination of specialized sample preparation, enabling measurements with conventional microwave on-wafer probes. To facilitate comparison with experimental measurements, an analysis tool based on the finite element method has been developed to solve detailed 3-D thermal models of bipolar transistors, including emitter metalization and trench-isolation effects. Thermal resistance measurements have been made on a collection of 9 single emitter silicon bipolar and 6 trench-isolated SiGe heterojunction bipolar transistors and compared to results from theoretical models. In addition, a collection of 15 GaAs heterojunction bipolar transistors have been studied theoretically and compared to measurements from a previous study. Results for silicon bipolar devices show that significant reductions in thermal resistance are achieved by using high aspect ratio emitter geometries. Comparison of results for silicon bipolar devices with trench-isolated SiGe devices of a similar emitter geometry show a threefold increase in thermal resistance due to the presence of trench isolation. This increase in thermal resistance is found to be attributable in roughly equal parts to the two isolation components, namely the deep and shallow trenches. The thermal resistance is found to scale weakly with emitter area for the small devices studied here, an effect which is most apparent in the GaAs devices. The origin of this effect is found to be the 3-D nature of the heat flow in the smallest devices. Emitter metalization is found to play a role in reducing the thermal resistance for high thermal resistance devices. Additionally, the emitter metalization is found to significantly increase the uniformity of the temperature across the emitter.
Item Metadata
Title |
Determination of self-heating in bipolar and heterojunction bipolar transistors by measurement and simulation
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2000
|
Description |
Self-heating in bipolar transistors, the effect which causes a rise in the device junction temperature
due to the electrical power dissipation, is of interest for several reasons, including
device reliability, model parameter extraction and electrothermal modeling. Self-heating is
most commonly quantified by a thermal resistance, which relates the device steady-state
temperature and power dissipation. In this work we present an improved setup for measuring
thermal resistance, based on an isothermal characterization of the device by means
of a pulsed-bias experiment. A 30 times increase in bias-pulse speed, compared to previous
setups, allows for the first time, accurate measurements to be made on devices with
submicron emitter dimensions. Simultaneous to increased performance, we have achieved a
significant reduction in the complexity of the setup through the elimination of specialized
sample preparation, enabling measurements with conventional microwave on-wafer probes.
To facilitate comparison with experimental measurements, an analysis tool based on the
finite element method has been developed to solve detailed 3-D thermal models of bipolar
transistors, including emitter metalization and trench-isolation effects.
Thermal resistance measurements have been made on a collection of 9 single emitter
silicon bipolar and 6 trench-isolated SiGe heterojunction bipolar transistors and compared
to results from theoretical models. In addition, a collection of 15 GaAs heterojunction
bipolar transistors have been studied theoretically and compared to measurements from a
previous study. Results for silicon bipolar devices show that significant reductions in thermal
resistance are achieved by using high aspect ratio emitter geometries. Comparison of results
for silicon bipolar devices with trench-isolated SiGe devices of a similar emitter geometry
show a threefold increase in thermal resistance due to the presence of trench isolation. This
increase in thermal resistance is found to be attributable in roughly equal parts to the two
isolation components, namely the deep and shallow trenches. The thermal resistance is found
to scale weakly with emitter area for the small devices studied here, an effect which is most
apparent in the GaAs devices. The origin of this effect is found to be the 3-D nature of the
heat flow in the smallest devices. Emitter metalization is found to play a role in reducing the
thermal resistance for high thermal resistance devices. Additionally, the emitter metalization
is found to significantly increase the uniformity of the temperature across the emitter.
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Extent |
5084406 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-07-13
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0065349
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2000-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.