IC Package Warpage Structures for CoWoS Underfill Delamination
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Solution Overview
Problem
The challenge in semiconductor packaging is to address the issue of warpage and delamination in integrated circuit packages, particularly in chip-on-wafer-on-substrate (CoWoS) configurations, due to stress accumulation in die-to-die underfill portions, which can lead to cracking and structural instability.
Innovation Solution
The implementation of front-side and backside warpage control structures, where the front-side structure comprises disconnected portions with wider gaps than the die-to-die underfill, and the backside structure overlaps with the underfill edges, embedded within the package substrate, to relieve stress and prevent delamination and warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If die-to-die underfill is used to fill gaps between integrated circuit dies, then structural support and stress distribution are improved, but warpage and delamination occur due to stress accumulation in the underfill portions
Solution Approach 1:
The underfill structure is segmented into two distinct portions: a die-to-die underfill portion filling the gap between dies, and a wider stress relief underfill portion extending beyond the dies. This segmentation allows each portion to serve different functions - structural support and stress distribution respectively - thereby resolving the contradiction between providing structural support and preventing warpage/delamination.
Solution Approach 2:
Different regions of the underfill structure are given different widths and properties. The stress relief underfill portion is intentionally made wider than the die-to-die underfill portion to create a stress relief zone. This local quality differentiation enables the structure to provide both structural support where needed and stress relief where required, preventing warpage and delamination.
2Strength
If continuous underfill is applied to fill all gaps, then structural integrity is enhanced, but stress accumulation leads to cracking and delamination
Solution Approach 1:
The underfill is segmented into functional zones with different widths. The stress relief underfill portion is wider and acts as a stress distribution zone, while the die-to-die underfill portion provides structural support. This segmentation prevents stress accumulation by distributing stresses across the wider portion, thereby preventing cracking and delamination while maintaining structural integrity.
Solution Approach 2:
The wider stress relief underfill portion, which extends beyond the dies, is designed to accommodate and distribute the stresses that would otherwise accumulate and cause damage. By providing this extra width, the structure converts potential harmful stress concentration into a beneficial stress distribution mechanism, preventing cracking and delamination.
Data Source
AI summary
A package includes a package substrate, the package substrate having a first side and a second side opposite to the first side, a package component bonded to the first side of the package substrate, a front-side warpage control structure attached to the first side of the package substrate, and a backside warpage control structure embedded in the package substrate from the second side of the package substrate. The front-side warpage control structure includes a first disconnected structure and a second disconnected structure laterally separated from each other by a gap. The backside warpage control structure includes a third disconnected structure and a fourth disconnected structure laterally separated from each other.