GaN HEMT Package Layout for High-Voltage Reliability
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Solution Overview
Problem
Reliable fabrication of large GaN HEMT devices for high-voltages (e.g., greater than 600V) with low on-resistances (e.g., less than 50 mohms) has proven difficult.
Innovation Solution
Design and packaging improvements for III-N devices, including a hybrid configuration of enhancement-mode and depletion-mode transistors, use of varying wire-bond diameters, a stress buffer layer, and specific dielectric layer structures to enhance reliability and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If GaN HEMT devices are designed for high-voltages (greater than 600V) with low on-resistances (less than 50 mohms), then power handling capability and efficiency are improved, but fabrication reliability and device robustness deteriorate
Solution Approach 1:
The device is divided into multiple fingers (e.g., 10 fingers) that are arranged in parallel. Each finger handles a portion of the total current and voltage, distributing the electrical stress across multiple discrete structures. This segmentation allows the device to achieve high power handling capability while maintaining fabrication reliability, as each individual finger can be manufactured with standard processes rather than requiring a single large-scale structure.
Solution Approach 2:
Different regions of the device are optimized with different structural characteristics. The drain region features a multi-pad configuration with varying wire-bond diameters (larger diameters for longer bonds), while the source region uses multiple source pads. The gate structure includes specific dielectric layers with different stress characteristics. These localized quality variations enable the device to handle high voltages and currents reliably without compromising overall fabrication yield.
2Stability of the object's composition
If wire-bonds with varying diameters are used to connect drain pads to terminals, then thermal cycling robustness is improved, but manufacturing complexity increases
Solution Approach 1:
The wire-bond diameter is optimized locally based on the specific bond length and thermal stress requirements. Longer wire-bonds (connecting drain pads farther from the terminal) use larger diameters to withstand greater thermal cycling stresses, while shorter bonds use smaller diameters. This localized optimization improves thermal cycling robustness without requiring all wire-bonds to be uniformly large, thereby controlling manufacturing complexity.
Solution Approach 2:
The wire-bond diameter parameter is varied systematically based on bond length and position. By changing this physical parameter to match the specific mechanical and thermal requirements of each connection point, the device achieves enhanced thermal cycling robustness. The variation in diameter is implemented through controlled manufacturing processes that can accommodate parameter changes without significantly increasing complexity.
3Reliability
If multiple dielectric layers with compressive stress are added to the metal structure, then device reliability under thermal stress is improved, but manufacturing process complexity increases
Solution Approach 1:
Dielectric layers are introduced with specific compressive stress parameters to counteract thermal expansion stresses during operation. The stress magnitude and layer thickness are carefully controlled to provide the necessary mechanical support and stress compensation. By optimizing these parameters, the device achieves improved reliability under thermal stress while the manufacturing process remains manageable through standardized deposition techniques.
Solution Approach 2:
The metal interconnect structure is combined with multiple dielectric layers to create a composite structure. The dielectric materials (such as silicon nitride and silicon oxide) provide compressive stress that compensates for thermal stresses in the metal layers. This composite approach improves device reliability by leveraging the complementary mechanical properties of different materials, while the layering can be implemented using existing semiconductor manufacturing processes.
4Reliability
If larger wire-bond diameters are used for longer wire-bonds, then connection reliability is improved, but material usage and cost increase
Solution Approach 1:
Wire-bond diameter is optimized locally based on the specific connection requirements. Longer wire-bonds that span greater distances and experience higher mechanical stress use larger diameters for improved reliability. Shorter wire-bonds use smaller diameters, reducing material consumption. This localized optimization ensures connection reliability where needed while minimizing overall material usage and associated costs.
Solution Approach 2:
The wire-bond diameter parameter is systematically varied to match the mechanical and electrical requirements of each specific connection. By changing this parameter based on bond length and position, the device achieves optimal connection reliability while avoiding the use of uniformly large diameters that would waste material. The parameter variation is implemented through controlled manufacturing processes that can efficiently produce wire-bonds of different sizes.
Data Source
AI summary
An electronic component includes at least three terminals extending from a component package. The component includes a depletion-mode III-N transistor, and an enhancement-mode transistor in the package. A gate electrode of the enhancement-mode transistor is electrically connected to the first terminal, a source electrode of the enhancement-mode transistor and a gate electrode of the depletion-mode III-N transistor are electrically connected to the second terminal, a drain electrode of the enhancement-mode transistor is electrically connected to a source electrode of the depletion-mode III-N transistor, and a drain electrode of the depletion-mode III-N transistor is electrically connected to the third terminal. The drain electrode includes multiple drain pads each sequentially a further distance from the third terminal, where a wire-bond extends from each drain pad to the third terminal, each wire-bond having a length, where a diameter of the longest wire-bond is greater than the diameter of the shortest wire-bond.