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Investigation of Device- and Circuit-Level Reliability of Inverse-Mode Silicon-Germanium Heterojunction Bipolar
Taeyeong Kim1, Garam Kim2, Moon-Kyu Cho3
1Department of Artificial Intelligence Semiconductor Engineering, Hanyang University, Seoul 04763, Republic of Korea.
Sensors (Basel, Switzerland)
|November 27, 2024
Summary
This study investigates the reliability of silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) in inverse mode under DC stress. Results show varying impacts on analog amplifier performance, with transimpedance gain decreasing and bandwidth increasing.
Area of Science:
- Semiconductor device physics
- Electronic materials science
- Analog circuit design
Background:
- Silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) are crucial components in modern electronics.
- Understanding the reliability of HBTs under stress is vital for predicting device lifetime and circuit performance.
- Inverse-mode operation of HBTs presents unique reliability challenges compared to forward-mode operation.
Purpose of the Study:
- To investigate the reliability of inverse-mode SiGe HBTs under various DC stress conditions.
- To evaluate the impact of device degradation on the performance of basic analog amplifiers.
- To compare the degradation characteristics of inverse-mode HBTs with their forward-mode counterparts.
Main Methods:
- Experimental characterization of SiGe HBTs under three different DC stress configurations (active bias, diode connection, off state) for up to 3000 s.
- Analysis of Gummel response changes to extract degradation in key device parameters like current gain (β), transconductance (gm), and base-to-emitter resistance (rπ).
- Small-signal equivalent circuit modeling and simulation of single-stage analog amplifiers to assess circuit-level performance metrics (gain, bandwidth) under accumulated stress.
Main Results:
- Device degradation was observed under all tested stress configurations.
- Extracted parameters showed significant changes, with comparisons made to forward-mode SiGe HBTs.
- Simulations indicated that transimpedance gain decreases and operation bandwidth increases due to device degradation.
- Voltage amplifiers demonstrated considerably less performance change compared to other amplifier types.
Conclusions:
- Inverse-mode SiGe HBTs exhibit reliability concerns under DC stress, affecting analog circuit performance.
- The extent of degradation and its impact on circuit metrics vary depending on the stress configuration and amplifier type.
- Voltage amplifiers appear more robust against the degradation effects observed in this study.
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