Semiconductor Lid Overhang Structure for CoWoS Heat and Warpage
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Solution Overview
Problem
Current semiconductor packaging technologies face challenges in managing heat dissipation and mechanical stability, particularly in Chip-on-Wafer-on-Substrate (CoWoS) structures, where high-power dies generate significant heat and external stress can cause warpage and cracks in electrical connectors.
Innovation Solution
A semiconductor structure incorporating a lid with overhang parts attached to a board to prevent warpage and cold joints, and surrounding corner sidewalls to protect electrical connectors, utilizing a combination of thermal interface materials and adhesives for effective heat dissipation and mechanical reinforcement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-power dies are integrated into CoWoS structures to increase component density, then integration density is improved, but heat dissipation becomes more difficult and thermal management deteriorates
Solution Approach 1:
The lid is divided into multiple functional parts: a body portion covering the CoWoS structure, extended portions extending from the body, and overhang portions extending further outward. This segmentation allows different parts of the lid to perform specialized functions - the body provides general protection and heat dissipation, while the extended and overhang portions specifically address thermal management at the periphery where heat accumulation is most severe.
Solution Approach 2:
The lid structure transitions from a simple planar cover to a three-dimensional structure with multiple levels of extension. The body portion forms a first level, extended portions create a second level projecting outward, and overhang portions form a third level that extends beyond the extended portions. This multi-level dimensional approach increases the effective heat dissipation surface area without increasing the footprint area, enabling better thermal management while maintaining high integration density.
2Reliability
If external stress is applied to CoWoS structures during operation, then device functionality is maintained, but warpage and cracks in electrical connectors occur
Solution Approach 1:
The lid's extended and overhang portions act as preemptive protective structures that counteract external stress before it can cause damage. By extending beyond the perimeter of the CoWoS structure, these portions create a protective barrier that absorbs and distributes external forces, preventing warpage and cracks in the electrical connectors before they occur.
Solution Approach 2:
The lid is formed as a composite structure combining the body portion made from a first material and the extended/overhang portions made from a second material. This composite construction allows optimization of each portion for its specific function - the body material can be optimized for heat dissipation and protection, while the extended portion material can be optimized for stress resistance and structural reinforcement, creating a synergistic structure that simultaneously addresses both thermal management and mechanical stability.
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 heat dissipation and mechanical stability, reducing cracks in electrical connectors and warpage, resulting in a more reliable semiconductor structure with improved integration and component density.
Implementation Method 1
utilizing a combination of thermal interface materials and adhesives for effective heat dissipation
Implementation Method 2
utilizing a combination of thermal interface materials and adhesives for effective heat dissipation and mechanical reinforcement
Data Source
AI summary
A method of fabricating a semiconductor structure includes providing a first substrate comprising a first side and a second side opposite to the first side. A package is attached to the first side of the first substrate. A second substrate is attached to the second side of the first substrate. A plurality of electrical connectors is bonded between the second side of the first substrate and the second substrate. A lid is attached to the first substrate and the second substrate. The lid includes a ring part and a plurality of overhang parts. The ring part is over the first side of the first substrate. The plurality of overhang parts extends from corner sidewalls of the ring part toward the second substrate. The plurality of overhang parts are laterally aside the plurality of electrical connectors.