Stacked Semiconductor Package Encapsulation Against Moisture Warpage
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Solution Overview
Problem
Thin semiconductor packages are susceptible to warpage due to moisture absorption, which compromises their structural integrity and performance.
Innovation Solution
A semiconductor package design that includes a molding resin extending around semiconductor chips and an underfill fillet that covers the sides of the chips, preventing exposure to the environment and enhancing adhesive strength to mitigate warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the uppermost semiconductor chip is thinned to reduce package thickness, then the package becomes more compact and lightweight, but the underfill fillet becomes exposed to the outside environment and susceptible to moisture absorption
Solution Approach 1:
The molding resin is nested within the space between the uppermost chip and the chip beneath it, creating a protective enclosure for the underfill fillet. This nested structure allows the molding resin to extend into the gap and cap the underfill fillet's top surface, preventing moisture exposure while maintaining chip thinning.
Solution Approach 2:
The molding resin extends vertically into the gap between chips, utilizing the third dimension (height/depth) to provide protection. Instead of only lateral coverage, the molding resin penetrates the vertical space to cap the underfill fillet, solving the exposure problem caused by chip thinning.
2Device complexity
If the underfill fillet is exposed to the outside environment, then the semiconductor package structure is simpler, but the package becomes susceptible to warpage due to moisture absorption
Solution Approach 1:
The molding resin is positioned within the inter-chip gap, nesting its protective function inside the existing package structure. This nested arrangement provides warpage resistance without adding external components, maintaining structural simplicity while improving stability.
Solution Approach 2:
The molding resin acts as an intermediary barrier between the underfill fillet and the external environment. It mediates the interaction by providing a protective interface that prevents moisture ingress and reduces thermal stress, thereby preventing warpage.
3Ease of manufacture
If the underfill fillet is exposed to the outside environment, then manufacturing process is simpler, but defect rate increases due to moisture absorption
Solution Approach 1:
The molding resin is formed within the inter-chip gap using existing molding processes, nesting the protective function within the standard packaging workflow. This approach maintains manufacturing simplicity while significantly improving reliability by preventing moisture-related defects.
Solution Approach 2:
The molding resin is formed in advance during the packaging process, creating a protective enclosure for the underfill fillet before the product is put into service. This preliminary protective action prevents moisture absorption and reduces defect rates throughout the product lifecycle.
Data Source
AI summary
A semiconductor device includes a plurality of semiconductor chips sequentially stacked on a substrate, an underfill layer between the plurality of semiconductor chips and between the substrate and a lowermost one of the plurality of semiconductor chips, and a molding resin extending around the plurality of semiconductor chips. The molding resin extends to a space between an uppermost one of the plurality of semiconductor chips and a semiconductor chip sequentially beneath the uppermost one of the plurality of semiconductor chips.