Interconnect Seal Ring in Stacked Dies to Block Leakage and Cracking
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Solution Overview
Problem
Stacked-die structures with different operating voltages face issues of electrical leakage and moisture penetration, which can lead to cracking and delamination, especially during sawing and high accelerated steam testing, and existing seal ring structures with diodes are ineffective in addressing these issues.
Innovation Solution
A seal ring structure that eliminates the use of diodes by incorporating an interconnect structure, such as a backside through silicon via, to electrically isolate well structures and provide a physical barrier, reducing leakage paths and preventing moisture and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal ring structure with diodes is used to prevent moisture penetration and cracking, then the structural integrity is improved, but electrical leakage occurs between IC dies with different operating voltages
Solution Approach 1:
The patent removes the diode component from the seal ring structure entirely. Instead of using a seal ring with integrated diodes that caused electrical leakage between IC dies with different operating voltages, the invention extracts the sealing function from the electrical isolation function, achieving sealing without the harmful diode structure that created leakage paths.
Solution Approach 2:
The patent segments the seal ring structure into separate functional components: the seal ring itself made of inert material for structural sealing, and eliminates the diode-based electrical isolation. This segmentation allows the seal ring to perform only its sealing function without introducing electrical leakage, while electrical isolation is handled separately or eliminated through proper voltage level design.
2Reliability
If the seal ring structure is added to prevent cracking during sawing, then the manufacturing reliability is improved, but the device complexity increases
Solution Approach 1:
The patent merges the sealing function and the crack prevention function into a single integrated seal ring structure. Rather than adding separate components for sealing and for mechanical support during sawing, the seal ring itself provides both functions, thereby improving manufacturing reliability without proportionally increasing device complexity.
Solution Approach 2:
The seal ring structure is designed to perform multiple functions simultaneously: it provides moisture sealing, prevents cracking during sawing operations, and maintains structural integrity across IC dies with different operating voltages. This multi-functionality reduces the need for additional specialized components, keeping the overall device complexity manageable while achieving multiple reliability goals.
3Reliability
If diodes are included in the seal ring to provide electrical isolation, then the electrical performance is improved, but moisture penetration and cracking occur
Solution Approach 1:
The patent extracts the electrical isolation function from the seal ring structure by removing the diodes. The seal ring is redesigned to focus solely on physical sealing and structural support, while electrical isolation between IC dies with different voltages is achieved through alternative means such as voltage level design or separate isolation structures, thereby eliminating the moisture penetration issue caused by diode integration.
Data Source
AI summary
Some implementations described herein provide techniques and apparatuses for a stacked-die structure including a first integrated circuit device over a second integrated circuit device, where an operating voltage of the first integrated circuit device is different relative to an operating voltage of the second integrated circuit device. The first integrated circuit device includes a first portion of a seal ring structure of the stacked-die structure. The first portion includes an interconnect structure that connects a backside redistribution layer of the first integrated circuit device with first metal layers of the first integrated circuit device. The seal ring structure including the interconnect structure eliminates the use of diodes and electrically isolates well structures of the first integrated circuit device to reduce leakage paths relative to a stacked-die structure having a seal ring structure including a diode within the stacked-die structure. Furthermore, use of the interconnect structure as part of the seal ring structure substantially eliminates moisture and/or cracking from penetrating the stacked-die structure.