GaN Pad Opening And Trench Passivation Against Moisture Ingress
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Solution Overview
Problem
Integrated circuits (ICs) based on gallium nitride (GaN) fail temperature, humidity, bias (THB) coupon testing due to moisture and vapor entering through weak points in the through GaN trench and pad openings, causing damage to semiconductor devices and delamination of passivation layers.
Innovation Solution
An enhanced passivation scheme is implemented using a second passivation layer with low permeability for moisture and vapor, which lines the sidewalls of the trench and pad openings, preventing moisture and vapor from entering the IC and thus preventing delamination and damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard passivation layer is used, then the manufacturing process is simple, but moisture and vapor enter through weak points causing delamination and device damage
Solution Approach 1:
The passivation structure is divided into multiple discrete layers: a first passivation layer (e.g., silicon nitride) and a second passivation layer (e.g., silicon oxide), each serving specific protective functions. This segmentation allows each layer to address different failure modes - the first layer provides moisture barrier protection while the second layer provides mechanical stress relief, collectively preventing delamination and device damage without requiring a single complex material
Solution Approach 2:
The patent employs composite passivation structures combining different dielectric materials with complementary properties. The first passivation layer uses materials with low moisture permeability (such as silicon nitride), while the second passivation layer uses materials with different mechanical and electrical properties (such as silicon oxide). This composite approach creates a synergistic effect where the combination of layers provides superior protection compared to individual layers, addressing both moisture ingress and stress management requirements
2Adaptability or versatility
If the trench and pad opening structures are used, then device functionality is improved, but moisture and vapor ingress through weak points causing THB testing failure
Solution Approach 1:
The passivation layers are selectively applied to specific regions where moisture ingress is most problematic. The first passivation layer is deposited conformally to line the sidewalls of trenches and pad openings, providing localized moisture barrier protection at these critical interfaces. The second passivation layer is then applied to seal the top surfaces. This local quality approach targets the harmful effect (moisture ingress) precisely where it occurs in the trench and pad opening structures, preserving device functionality while preventing THB testing failure
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 enhanced passivation scheme allows the IC to pass THB coupon testing by reducing moisture and vapor ingress, preventing damage to semiconductor devices and conductive features, and maintaining the integrity of the passivation layers.
Implementation Method 1
a second passivation layer overlying the ILD layer, the conductive pad, and the first passivation layer, and further lining sidewalls of the first passivation layer in the pad opening and sidewalls of the ILD layer in the trench, where the second passivation layer has a lower permeability for moisture or vapor than the ILD layer
Data Source
AI summary
An integrated circuit (IC) comprising an enhanced passivation scheme for pad openings and trenches is provided. In some embodiments, an interlayer dielectric (ILD) layer covers a substrate and at least partially defines a trench. The trench extends through the ILD layer from a top of the ILD layer to the substrate. A conductive pad overlies the ILD layer. A first passivation layer overlies the ILD layer and the conductive pad, and further defines a pad opening overlying the conductive pad. A second passivation layer overlies the ILD layer, the conductive pad, and the first passivation layer, and further lines sidewalls of the first passivation layer in the pad opening and sidewalls of the ILD layer in the trench. Further, the second passivation layer has a low permeability for moisture or vapor relative to the ILD layer.