GaN HEMT Field Plate Layout for Defect-Sensitive Reliability
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Solution Overview
Problem
Gallium nitride (GaN) on-silicon lateral HEMT power devices face high device failure rates due to epitaxial growth defects, lattice mismatch, and back-end process-induced defects, which are not effectively detected during manufacturing, leading to performance degradation and increased costs.
Innovation Solution
Incorporating artificial field plates between the gate and source/drain contact structures in GaN HEMT devices to enhance defect detection sensitivity, improve electric-field uniformity, and reduce manufacturing costs by monitoring defects in the inter-metal dielectric layers and drift region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional manufacturing processes are used for GaN HEMT devices, then manufacturing costs are reduced, but defect detection sensitivity is insufficient leading to high device failure rates
Solution Approach 1:
The patent applies preliminary action by forming artificial field plates during the manufacturing process that proactively create controlled electric field regions before defects can cause device failure. These artificial field plates are positioned to pre-establish detection zones that will reveal defects during subsequent testing, allowing defective devices to be identified and removed before they reach the market.
Solution Approach 2:
The artificial field plates serve as an intermediary structure between the gate and source/drain regions. They mediate the detection process by creating enhanced electric field regions that interact with defects in the drift region and inter-metal dielectric layers, making otherwise undetectable defects visible through their effect on the electric field distribution and device characteristics.
2Measurement precision
If artificial field plates are added to enhance defect detection, then defect detection sensitivity improves, but device complexity increases
Solution Approach 1:
The artificial field plates create localized regions of enhanced electric field strength in specific areas of the device, particularly in the drift region and near the gate. This local quality enhancement allows defect detection to be focused where it is most needed, rather than requiring uniform complexity throughout the entire device structure. The field plates are strategically positioned to create detection zones only in critical areas.
3Measurement precision
If artificial field plates are used to monitor defects in drift region, then defect detection capability improves, but manufacturing precision requirements increase
Solution Approach 1:
The artificial field plates are segmented into multiple discrete structures positioned at different locations between the gate and source/drain regions. This segmentation allows each field plate to be independently formed using standard photolithography and deposition processes, reducing the overall manufacturing precision requirements compared to forming a single complex structure. The segmented approach also provides redundancy in defect detection coverage.
Data Source
AI summary
The present disclosure describes a semiconductor device having artificial field plates. The semiconductor device includes a first gallium nitride (GaN) layer on a substrate, an aluminum gallium nitride (AlGaN) layer on the first GaN layer, and a second GaN layer on the AlGaN layer. The first and second GaN layers includes different types of dopants. The semiconductor device further includes a gate contact structure in contact with the second GaN layer, first and second source/drain (S/D) contact structures in contact with the AlGaN layer, one or more artificial field plates between the gate contact structure and the first S/D contact structure. The first and second S/D contact structures are disposed at opposite sides of the gate contact structure. The one or more artificial field plates are separated from the first and second S/D contact structures and above the AlGaN layer.