Stacked Semiconductor Package Moisture Barrier for Chip Side Steps
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Solution Overview
Problem
Semiconductor packages are vulnerable to moisture penetration between chip-to-chip bonding layers, leading to instability and performance degradation under environmental stress such as high temperature, high humidity, and electrical stress.
Innovation Solution
Incorporation of a moisture barrier layer with a thickness of 5 μm or less, made of inorganic material, and a step cover layer with a thickness of 40 μm or less, made of organic material, to prevent moisture ingress and ensure uniform application over side steps between semiconductor chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional encapsulation structure is used without a moisture barrier layer, then the device complexity is reduced and manufacturing is easier, but moisture penetrates into the semiconductor package causing reliability degradation
Solution Approach 1:
The encapsulation structure is segmented into multiple functional layers: a step cover layer (first encapsulation layer) and a moisture barrier layer (second encapsulation layer). This segmentation allows each layer to perform its specific function - the step cover layer provides mechanical protection and covers side steps, while the moisture barrier layer specifically prevents moisture penetration, thereby improving reliability without excessive complexity increase.
Solution Approach 2:
The encapsulation structure uses composite materials with different properties - the step cover layer uses an organic material (epoxy molding compound) providing mechanical strength and flexibility, while the moisture barrier layer uses an inorganic material (silicon oxide, silicon nitride, or silicon oxynitride) providing moisture blocking properties. This composite approach achieves superior moisture resistance while maintaining structural integrity.
2Reliability
If the step cover layer thickness is increased to cover side steps, then moisture penetration is prevented, but manufacturing precision requirements increase and production difficulty increases
Solution Approach 1:
The step cover layer is designed with local quality - it has a maximum thickness of 40 μm or less specifically at the step coverage regions, which is sufficient to cover side steps and prevent moisture penetration at critical areas. This localized thickness control prevents excessive material deposition while ensuring adequate protection where needed, reducing manufacturing precision requirements compared to uniform thick coating.
Solution Approach 2:
The thickness parameter of the step cover layer is optimized to 40 μm or less, which is a critical parameter change that balances moisture protection capability with manufacturing feasibility. This parameter optimization ensures adequate step coverage while avoiding excessive thickness that would difficult to control during manufacturing.
3Reliability
If a moisture barrier layer is added to prevent moisture ingress, then reliability is improved, but the device complexity and manufacturing process complexity increase
Solution Approach 1:
The moisture barrier layer acts as an intermediary layer between the step cover layer and the semiconductor chips. This inorganic barrier layer specifically addresses moisture penetration without interfering with the mechanical protection function of the organic step cover layer. The intermediary structure allows each layer to perform its specialized function, improving reliability while keeping the overall structure manageable.
4Manufacturing precision
If the step cover layer thickness is reduced to 40 μm or less, then manufacturing precision is improved and production is easier, but coverage of side steps may be insufficient
Solution Approach 1:
The combination of organic step cover layer and inorganic moisture barrier layer creates a composite encapsulation system where the total protective function exceeds what either layer could achieve alone. The step cover layer provides mechanical coverage of side steps with controlled thickness (≤40 μm), and the moisture barrier layer adds moisture blocking capability, together ensuring both manufacturing feasibility and adequate side step coverage for reliability.
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 enhances the stability and reliability of semiconductor packages by preventing moisture penetration and reducing void formation and migration, ensuring stable operation under various environmental conditions.
Implementation Method 1
a moisture barrier layer covering an outer surface of the step cover layer
Data Source
AI summary
Provided is a semiconductor package including a first semiconductor chip, a plurality of second semiconductor chips stacked on the first semiconductor chip, a step cover layer surrounding side surfaces of the plurality of second semiconductor chips and covering side portions of the plurality of second semiconductor chips, wherein a maximum thickness of the step cover layer is 40 micrometers (μm) or less, and a moisture barrier layer covering an outer surface of the step cover layer.