Bidirectional HEMT Field-Plate Structure for Gate Edge Shielding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-electron-mobility transistors (HEMTs), particularly bidirectional FETs based on pGaN structures, face challenges in gate reliability and field reduction at the gate edge due to high voltage exposure, which is not adequately addressed in traditional unidirectional FETs.
Innovation Solution
A bidirectional HEMT structure with self-aligned field plates adjacent to gate structures and the surface of an active layer, completely enclosing source terminals to prevent gate crossing into implanted isolation regions, enhancing gate reliability and shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional unidirectional FET structure is used, then device simplicity is maintained, but gate reliability deteriorates under high voltage exposure
Solution Approach 1:
The device is divided into two symmetrical HEMT structures with separate gate structures (first gate structure and second gate structure), each capable of independent operation. This segmentation allows each gate to be optimized for high voltage reliability while maintaining overall device functionality.
Solution Approach 2:
Field plates are added as an additional dimensional element extending from the gate structures into the active layer. This third-dimensional extension (beyond the standard planar gate) provides enhanced field control and shielding without significantly increasing planar footprint, thereby improving reliability while controlling complexity.
2Adaptability or versatility
If gate structures are exposed to high voltage, then bidirectional operation capability is achieved, but field reduction at gate edge deteriorates
Solution Approach 1:
Field plates serve as intermediary elements between the gate structures and the high voltage environment. These plates extend into the active layer and provide gradual field termination, mediating the electric field distribution to prevent abrupt field reduction at the gate edge while enabling bidirectional high voltage operation.
Solution Approach 2:
The field plates are positioned to preemptively control the electric field distribution before high voltage is applied to the gates. By extending into the active layer in advance, they establish favorable field conditions that prevent harmful field reduction effects when the device operates in bidirectional mode.
3Reliability
If gate structures are shielded from high voltage, then gate reliability improves, but voltage blocking capability in ON and OFF states deteriorates
Solution Approach 1:
The field plates are nested within the device structure, extending from the gate regions into the active layer. This nested configuration provides shielding protection to the gates while simultaneously maintaining the device's voltage blocking capability, as the field plates are integrated into the overall power handling architecture rather than isolating the gates completely.
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 structure improves gate reliability by effectively shielding the gate structures from high voltage, ensuring reliable operation and preventing voltage blocking in both ON and OFF states.
Implementation Method 1
field plates adjacent to the first gate structure, the second gate structure and a surface of an active layer... effectively shielding the gate structures from high voltage
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to a bidirectional device, methods of manufacture and methods of operation. The structure includes: a first gate structure adjacent to a first source region; a second gate structure adjacent to a second source region; and field plates adjacent to the first gate structure, the second gate structure and a surface of an active layer of the first gate structure and the second gate structure.