Extended Seal Ring Structure for Wafer Bonding Interface Reliability

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Solution Overview

Problem

In wafer-to-wafer bonding technology, chipping can occur at the die interface during singulation, leading to humidity penetration and increased ohmic resistance, resulting in die rejection and failure.

Innovation Solution

An extended seal ring structure is introduced to bring the seal ring up through the bonding interface, creating a seal ring bond between the two wafers and spanning the bonding interface, providing better mechanical stress support and resisting humidity penetration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wafer-to-wafer bonding is performed without extended seal ring, then bonding process is simpler, but chipping occurs at die interface during singulation leading to humidity penetration and increased ohmic resistance

Engineering Contradiction:

Improvebonding interface reliabilityVSAvoidseal ring structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The seal ring structure is extended upward from the wafer surface before bonding occurs, creating a pre-formed barrier that will span the bonding interface. This preliminary structural preparation prevents chipping propagation and humidity penetration at the bonding interface without requiring complex post-bonding modifications

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The seal ring is extended in the vertical dimension (upward from wafer surface) rather than only in the planar dimension. This vertical extension allows the seal ring to span across the bonding interface between wafers, creating a three-dimensional protective structure that prevents harmful factors from reaching the bonding interface

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If extended seal ring structure is introduced to prevent chipping and humidity penetration, then bonding interface reliability is improved, but manufacturing process complexity increases

Engineering Contradiction:

Improvewafer stack mechanical stabilityVSAvoidseal ring formation process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The seal ring structure is divided into multiple segments or portions that can be formed independently and then integrated. The seal ring is extended upward in discrete sections that are subsequently bonded together, allowing each segment to be manufactured using standard processes while achieving the overall extended structure through modular assembly

Inventive Principle:

Principle #1Segmentation

3Object-affected harmful factors

If seal ring is extended through bonding interface, then chipping propagation is reduced and humidity penetration is prevented, but structural complexity increases

Engineering Contradiction:

Improvehumidity and contaminant infiltrationVSAvoidseal ring geometry

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The seal ring is formed as a thin film or shell structure that extends upward from the wafer surface. This thin-film approach provides effective barrier protection against humidity and contaminants while maintaining a relatively simple geometric form that can be manufactured using standard thin-film deposition and patterning techniques

Inventive Principle:

Principle #30Flexible shells and thin films

Data Source

PatentUS12283552B2Extended seal ring structure on wafer-stacking

Publication Date: 2025.04.22 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Embodiments include a wafer-on-wafer bonding where each wafer includes a seal ring structure around die areas defined in the wafer. Embodiments provide a further seal ring spanning the interface between the wafers. Embodiments may extend the existing seal rings of the wafers, provide an extended seal ring structure separate from the existing seal rings of the wafers, or combinations thereof.