Power Semiconductor Passivation Layer Humidity Barrier
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Solution Overview
Problem
Power semiconductor devices face degradation and instability due to high humidity and electric fields, leading to corrosion and breakdown, especially in high voltage applications, with existing passivation layers failing to effectively block humidity and maintain long-term reliability.
Innovation Solution
A power semiconductor device with a passivation layer structure comprising a semi-insulating layer, a silicon nitride layer, and an undoped silicate glass layer, where the undoped silicate glass layer acts as a barrier to humidity, protecting the silicon nitride layer and ensuring efficient charge blocking, while an organic dielectric layer enhances adhesion and prevents moisture ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon nitride layer is used as passivation layer, then electrical insulation and charge blocking are improved, but humidity penetration and corrosion occur leading to long-term reliability degradation
Solution Approach 1:
The passivation structure is divided into multiple functional layers: silicon nitride layer for electrical insulation and charge blocking, undoped silicate glass layer for humidity barrier, and organic dielectric layer for additional moisture protection. Each layer addresses specific requirements without compromising others.
Solution Approach 2:
The undoped silicate glass layer acts as an intermediary barrier between the silicon nitride layer and the external environment. It prevents humidity from reaching the silicon nitride layer while allowing the silicon nitride layer to perform its electrical insulation function effectively.
2Strength
If phosphorous is added to silicon dioxide to strengthen material, then mechanical strength is improved, but ion migration and breakdown voltage instability occur
Solution Approach 1:
Instead of using phosphorous-doped silicate glass (PSG) which provides strength but causes ion migration, the invention uses undoped silicate glass that does not contain mobile ions. The structural support function is provided by the multi-layer structure itself rather than relying on dopants.
Solution Approach 2:
The invention changes the compositional parameter of the glass layer from doped (PSG, BPSG) to undoped silicate glass. This parameter change eliminates ion migration while maintaining the humidity barrier function through the layered structure design.
3Object-affected harmful factors
If beveled termination structure is used, then electric field crowding is reduced, but manufacturing complexity increases
Solution Approach 1:
The beveled termination structure creates an equipotential surface that distributes the electric field uniformly across the termination region. This reduces electric field crowding at sharp edges while the passivation layers provide additional protection against humidity ingress.
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 provides robust and long-term reliability in high humidity environments by effectively blocking humidity and preventing corrosion, thereby maintaining the integrity and performance of the power semiconductor device.
Implementation Method 1
an undoped silicate glass layer arranged on the silicon nitride layer and attached to it... the undoped silicate glass layer acts as a barrier to humidity
Implementation Method 2
some ions such as sodium (Na) and potassium (K) ions are known to migrate through the oxide layers resulting in instability of the breakdown voltage
Data Source
AI summary
A power semiconductor device is provided comprising a wafer, wherein in a termination region of the device a passivation layer structure is formed at least on a portion of a surface of the wafer and the passivation layer structure comprises in an order from the surface of the wafer in a direction away from the wafer a semi-insulating layer, a silicon nitride layer, an undoped silicate glass layer and an organic dielectric layer. The silicon nitride layer has a layer thickness of at least 0.5 μm. The organic dielectric layer its attached to the undoped silicate glass layer and the undoped silicate glass layer is attached to the silicon nitride layer.