HEMT Helping Gate Layout for Threshold Stability and Low ON Resistance
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Solution Overview
Problem
High-electron-mobility transistors (HEMTs) face issues with electron trapping in the semiconductor capping structure and heterojunction, leading to variation in threshold voltage and increased ON resistance, which affects power efficiency and reliability.
Innovation Solution
Incorporating a helping gate with a lower work function outside the active region, directly contacting the semiconductor capping structure, to increase gate leakage and inject holes and release trapped electrons, thereby reducing ON resistance and threshold voltage variation without altering the threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional gate structure is used in HEMT, then the device structure is simple, but electron trapping in the semiconductor capping structure causes threshold voltage variation and increased ON resistance
Solution Approach 1:
The gate structure is segmented into two distinct gates: a first gate positioned over the active region for primary control, and a second gate positioned outside the active region specifically to address electron trapping. This segmentation allows each gate to perform its specialized function independently, resolving the contradiction by adding a dedicated component rather than complicating the existing gate structure.
Solution Approach 2:
The semiconductor capping structure serves as an intermediary between the two gates and the heterojunction. It is strategically positioned to allow the second gate to influence trapped electrons in the heterojunction while maintaining electrical isolation where needed. This intermediary structure enables the second gate to mitigate threshold voltage variation without directly interfering with the primary gate's control function.
2Reliability
If the helping gate directly contacts the semiconductor capping structure to increase gate leakage, then trapped electrons are released and ON resistance decreases, but the threshold voltage may be altered
Solution Approach 1:
The second gate is positioned locally outside the active region, creating a localized effect that is confined to specific areas. This local positioning allows the second gate to release trapped electrons and reduce ON resistance in the isolation regions without significantly affecting the threshold voltage control in the active channel region, thus resolving the contradiction between improving power efficiency and maintaining threshold voltage precision.
Solution Approach 2:
The second gate applies a partial action by targeting only the electron trapping issue in the isolation regions outside the active region, rather than attempting to control all electrical characteristics. This partial action approach allows the second gate to release trapped electrons and improve power efficiency while leaving the primary threshold voltage control function to the first gate, thus avoiding threshold voltage instability.
3Ease of manufacture
If electrons are trapped in the heterojunction and semiconductor capping structure, then the device can be manufactured with standard processes, but ON resistance increases and power efficiency decreases
Solution Approach 1:
The second gate is configured to proactively address electron trapping before it significantly degrades device performance. By positioning the second gate to continuously or periodically release trapped electrons through controlled gate leakage, the system performs preliminary action to prevent electron accumulation that would otherwise increase ON resistance and reduce power efficiency, while maintaining compatibility with standard manufacturing processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces ON resistance and threshold voltage variation, enhancing power efficiency and reliability by releasing trapped electrons through higher gate leakage, while maintaining the original threshold voltage.
Implementation Method 1
Incorporating a helping gate with a lower work function outside the active region, directly contacting the semiconductor capping structure, to increase gate leakage and inject holes and release trapped electrons
Implementation Method 2
Incorporating a helping gate with a lower work function outside the active region, directly contacting the semiconductor capping structure
Data Source
AI summary
Some embodiments relate to an integrated device, including a semiconductor film accommodating a two-dimensional carrier gas (2DCG) over a substrate; a first source/drain electrode over the semiconductor film; a second source/drain electrode over the semiconductor film; a semiconductor capping structure between the first source/drain electrode and the second source/drain electrode; a first gate overlying the semiconductor capping structure and between the first source/drain electrode and the second source/drain electrode in a first direction; a first helping gate overlying the semiconductor capping structure and bordering the first gate, wherein the first helping gate and the second source/drain electrode are arranged in a line extending in a second direction transverse to the first direction.