Wafer-on-Wafer Continuous Seal Ring for Hybrid Bond Reliability
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Solution Overview
Problem
Wafer-on-wafer packaging faces challenges with discontinuous seal rings, leading to reduced bonding strength, structural instability, vulnerability to cracks and moisture, and lack of effective charge discharge and delamination monitoring.
Innovation Solution
A continuous seal ring is formed by vertically aligning and bonding bottom and top seal rings using hybrid bonding, with an additional active region for electrostatic discharge protection and a delamination monitoring structure for efficient detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If wafer-on-wafer packaging uses separate bottom and top seal rings, then the packaging structure can be formed, but the seal ring is discontinuous leading to reduced bonding strength and structural instability
Solution Approach 1:
The patent merges the separate bottom seal ring and top seal ring into a continuous seal ring structure. The bottom seal ring and top seal ring are positioned to overlap and form a continuous protective barrier around the active regions, eliminating the discontinuity that caused reduced bonding strength and structural instability.
2Ease of manufacture
If discontinuous seal rings are used in wafer-on-wafer packaging, then manufacturing is simpler, but the structure becomes vulnerable to cracks and moisture penetration
Solution Approach 1:
The bottom seal ring and top seal ring are combined to form a continuous seal that prevents crack propagation and moisture penetration. The continuous structure eliminates gaps that would otherwise allow harmful factors to reach the active regions, while maintaining manufacturing simplicity through the wafer-on-wafer bonding process.
3Reliability
If traditional packaging structures are used, then device complexity is lower, but there is no effective charge discharge and delamination monitoring capability
Solution Approach 1:
The seal ring structure is given multiple functions: it provides mechanical sealing, electrostatic discharge protection through conductive paths, and delamination monitoring through integrated sensing capabilities. This multi-functionality enhances reliability without requiring entirely separate systems for each protection mechanism.
Solution Approach 2:
The packaging structure incorporates preliminary protection mechanisms including electrostatic discharge paths and delamination monitoring structures that are built in during the wafer fabrication and bonding process, enabling early detection and protection before failures occur.
4Strength
If wafer-on-wafer bonding is performed without continuous seal ring alignment, then manufacturing is easier, but bonding strength and structural integrity are reduced
Solution Approach 1:
The bottom seal ring and top seal ring are designed to overlap and merge into a continuous structure, which provides tolerance for alignment variations while still achieving strong bonding. The merging approach allows the seal rings to work together to create a robust continuous seal even with minor misalignments.
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 continuous seal ring enhances bonding strength, stability, and protection against electrostatic damage, while the monitoring structure improves reliability and efficiency in detecting delamination.
Implementation Method 1
The bottom die and the top die are bonded through hybrid bonding between the first bonding layer and the second bonding layer at an interface therebetween
Implementation Method 2
an additional active region for electrostatic discharge protection
Data Source
AI summary
A package structure is provided. The package structure includes a bottom die and a top die. The bottom die includes: a first active region surrounded by a first seal ring region; a first seal ring region including a bottom seal ring; and a first bonding layer disposed on a front side of the bottom die. The top die includes: a second active region surrounded by a second seal ring region; a second seal ring region including a top seal ring; and a second bonding layer disposed on a front side of the top die. The bottom die and the top die are bonded through hybrid bonding between the first bonding layer and the second bonding layer at an interface therebetween such that the bottom seal ring and the top seal ring are vertically aligned and are operable to form a continuous seal ring.