Seal Ring Thermal Path for 3DIC Heat Dissipation
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Solution Overview
Problem
In Three-Dimensional Integrated Circuits (3DICs), there is a challenge in efficiently dissipating heat generated in inner dies due to the presence of non-conductive materials like underfill and molding compound between stacked dies, which hinder effective heat conduction to heat spreaders.
Innovation Solution
The implementation of a seal-ring-comprising thermal path, which includes conductive through-vias, metal lines, and seal rings connected to the edges of dies and interposers, forming a continuous thermal path to efficiently conduct heat from inner dies to heat spreaders through interconnected metal features and thermal conductive films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If micro-channels are built inside silicon substrates for heat dissipation, then heat dissipation efficiency is improved, but manufacturing cost and time-to-market increase
Solution Approach 1:
The invention divides the heat dissipation function into two parts: (1) seal rings on individual dies that collect heat locally, and (2) a heat spreader that distributes heat across the package. This segmentation allows standard manufacturing processes to be used while achieving effective heat dissipation, avoiding the need for complex micro-channel fabrication.
Solution Approach 2:
The seal ring acts as an intermediary thermal conduction path between the die and the heat spreader. By introducing this intermediate thermal conductor, the invention enables heat transfer through existing packaging materials without requiring modification of the silicon substrate itself, thus maintaining manufacturing simplicity.
2Device complexity
If non-conductive materials like underfill and molding compound are used between stacked dies, then die stacking is enabled, but heat conduction from inner dies is hindered
Solution Approach 1:
The invention segments the heat conduction path by placing seal rings at specific locations on each die that directly contact the heat spreader. This creates dedicated thermal pathways that bypass the non-conductive underfill and molding materials, allowing die stacking to be maintained while restoring heat conduction capability.
Solution Approach 2:
The invention extracts the heat conduction function from the bulk packaging materials (underfill and molding compound) and concentrates it into specific seal ring regions. This extraction allows the non-conductive materials to remain for structural purposes while thermal conduction is handled by the metal seal rings.
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
This solution enhances heat dissipation efficiency by creating multiple thermal paths with high thermal conductivity, reducing the temperature difference caused by generated heat and improving overall heat spreader performance, as indicated by a lower Ψjc value of 0.88 K/W compared to 0.99 K/W without the seal-ring-comprising thermal paths.
Implementation Method 1
The seal ring is thermally coupled to the plurality of through-vias... conducting heat in the die to the seal ring and conducting the heat from the seal ring to a metal line in the interposer
Data Source
AI summary
A package includes a die, which includes a semiconductor substrate, a plurality of through-vias penetrating through the semiconductor substrate, a seal ring overlapping and connected to the plurality of through-vias, and a plurality of electrical connectors underlying the semiconductor substrate and connected to the seal ring. An interposer is underlying and bonded to the die. The interposer includes a substrate, and a plurality of metal lines over the substrate. The plurality of metal lines is electrically coupled to the plurality of electrical connectors. Each of the plurality metal lines has a first portion overlapped by the first die, and a second portion misaligned with the die. A heat spreader encircles the die and the interposer. A wire includes a first end bonded to one of the plurality of metal lines, and a second end bonded to the heat spreader.