Multilayer Oxide Encapsulation for Humidity-Robust Semiconductor Dies
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Solution Overview
Problem
Conventional semiconductor devices using oxide layers, such as SiO2, suffer from high interface state densities and are susceptible to environmental degradation due to moisture ingress, leading to performance degradation and corrosion, especially in high power and high frequency applications.
Innovation Solution
A multi-layer environmental barrier is implemented using alternating sublayers of different oxide materials, such as aluminum oxide and silicon oxide, deposited via Atomic Layer Deposition (ALD), to provide enhanced protection against moisture and contaminants, with varying diffusion coefficients and densities to impede the ingress of water and ionic species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single layer of oxide material (e.g., SiO2 or SiN) is used as an environmental barrier, then the device structure is simple and manufacturing is easier, but the barrier is prone to defects such as pin holes and columnar structures that allow moisture penetration
Solution Approach 1:
The single oxide barrier layer is segmented into multiple alternating layers of different oxide materials (e.g., SiO2, SiOx, SiNx). This segmentation creates a multi-layer environmental barrier where each layer contributes to blocking moisture and contaminants, with the combined structure providing superior protection compared to a single layer while maintaining manufacturing feasibility through established deposition techniques.
Solution Approach 2:
The environmental barrier is constructed as a composite structure using multiple oxide materials with different properties. The alternating layers of oxides with varying densities, diffusion coefficients, and chemical compositions create a composite barrier that leverages the strengths of each material to prevent moisture penetration and protect the underlying semiconductor device.
2Reliability
If PECVD SiN is used as an environmental barrier, then a better seal is formed compared to SiO2, but the layer is prone to defects such as pin holes and columnar structures
Solution Approach 1:
The PECVD SiN layer is segmented into multiple thin alternating oxide layers. This segmentation distributes the sealing function across multiple interfaces and reduces the formation of continuous pin holes and columnar structures that occur in thick single layers. Each thin oxide layer acts as an independent barrier, and the cumulative effect provides superior moisture protection.
Solution Approach 2:
The deposition parameters are changed by using Atomic Layer Deposition (ALD) instead of PECVD for forming the oxide layers. ALD provides better control over layer thickness and composition, resulting in denser, more uniform layers with fewer defects. The alternating oxide structure also changes the physical parameters of the barrier, creating a more effective moisture block.
3Reliability
If conventional oxide layers are used for passivation, then the interface protection is insufficient, but the manufacturing process is simpler
Solution Approach 1:
The passivation structure uses a composite of multiple oxide materials deposited in alternating layers. This composite structure provides superior interface protection by creating multiple barriers at the semiconductor-oxide interface, reducing interface states and improving surface electron mobility while maintaining compatibility with standard semiconductor fabrication processes.
Solution Approach 2:
Different oxide materials are used at different locations within the passivation structure to optimize local properties. The alternating layers provide varying degrees of protection against different types of degradation, with each material selected for its specific properties such as interface quality, moisture barrier performance, or stress characteristics.
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 multi-layer environmental barrier significantly reduces moisture and contaminant ingress, improving the reliability and performance of semiconductor devices by preventing corrosion and degradation, while maintaining uniform thickness and conformality across the device.
Implementation Method 1
varying diffusion coefficients and densities to impede the ingress of water and ionic species
Implementation Method 2
deposited via Atomic Layer Deposition (ALD)
Data Source
AI summary
A semiconductor die includes a semiconductor body, and a multi-layer environmental barrier on the semiconductor body. The multi-layer environmental barrier includes first and second sublayers of first and second oxide materials, respectively, where the first oxide material is different than the second oxide material. Related devices and fabrication methods are also discussed.