Semiconductor Package Buffer Layer Layout for CTE Stress Relief
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Solution Overview
Problem
The semiconductor industry faces challenges in reducing stress and warpage due to coefficient of thermal expansion (CTE) mismatch in semiconductor packages, which can lead to issues like delamination and warping, affecting device yield and reliability.
Innovation Solution
A semiconductor package design that incorporates a buffer layer extending beyond the edges of the package components, with controlled sidewall characteristics to mitigate stress, and multiple buffer layers for enhanced stress reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a buffer layer is added to reduce stress and warpage, then reliability improves, but device complexity increases
Solution Approach 1:
A buffer layer is introduced as an intermediary component between the package components and the external environment. This buffer layer absorbs and distributes thermal expansion stresses, preventing direct stress transmission to the package components and reducing warpage, thereby improving reliability without fundamentally changing the core package structure
Solution Approach 2:
The buffer layer's material properties and geometric parameters (such as thickness, lateral dimensions, and material composition) are optimized to achieve the desired stress reduction effect. By adjusting these parameters, the buffer layer can be tailored to match the thermal expansion characteristics of adjacent components, minimizing stress while maintaining a relatively simple structure
2Reliability
If the buffer layer extends beyond package component edges, then stress reduction improves, but manufacturing precision requirements increase
Solution Approach 1:
The buffer layer is formed to extend beyond the edges of package components during the packaging process, before final assembly and trimming operations. This preliminary extension ensures that the buffer layer provides adequate stress relief coverage, and subsequent manufacturing steps can trim or planarize the buffer layer to achieve final dimensional precision without compromising the stress reduction function
3Reliability
If multiple buffer layers are used to enhance stress reduction, then reliability improves, but device complexity increases
Solution Approach 1:
The stress buffering function is divided into multiple discrete buffer layers, each positioned at different locations or orientations within the package structure. This segmentation allows each buffer layer to address specific stress patterns or thermal expansion mismatches between different component interfaces, providing enhanced and more targeted stress reduction compared to a single monolithic buffer layer
Data Source
AI summary
A device includes a package component including an interconnect structure on a first side of a substrate; metal pads on the interconnect structure; a semiconductor die connected to a second side of the substrate; a dielectric material surrounding the package component; a passivation layer extending over the package component and over the dielectric material; a first buffer layer over the passivation layer, wherein the first buffer layer extends over the package component and over the dielectric material, wherein a width of the first buffer layer is greater than a width of the package component and is less than a width of the passivation layer; and conductive connectors penetrating the passivation layer and the first buffer layer to physically contact the metal pads.