Seal Ring Metal Pad Structure for Crack-Resistant Passivation

Solution Overview

Problem

In wafer-level packaging technology, seal ring structures in high stress regions are susceptible to cracking and delamination during fabrication and use, due to the stress concentrations around the metal pads and passivation layers.

Innovation Solution

The formation of seal rings with metal pads having a stair-step shape reduces stress concentrations by allowing more uniform deposition of passivation material and enhancing attachment within the passivation layer, thereby decreasing the risk of delamination and cracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal pads are formed with conventional shapes in high stress regions, then the seal ring structure can be formed, but stress concentrations occur leading to cracking and delamination

Engineering Contradiction:

Improveseal ring integrityVSAvoidstress resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The metal pad is divided into multiple stepped levels rather than forming a single continuous structure. This segmentation creates multiple interfaces that distribute stress more evenly, preventing stress concentration at any single location and eliminating the root cause of cracking and delamination in high stress regions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The metal pad structure transitions from a two-dimensional planar shape to a three-dimensional stepped configuration. By adding the vertical dimension with multiple levels, the structure creates additional stress distribution pathways and reduces stress concentration through the increased structural complexity in the depth direction.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If conventional metal pad shapes are used, then fabrication can proceed, but stress concentrations cause cracking and delamination during fabrication and use

Engineering Contradiction:

Improvefabrication yieldVSAvoidcrack resistance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The metal pad is divided into multiple stepped levels rather than forming a single continuous structure. This segmentation creates multiple interfaces that distribute stress more evenly, preventing stress concentration at any single location and eliminating the root cause of cracking and delamination in high stress regions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The stepped configuration is built into the metal pad structure during the initial fabrication process, before subsequent packaging and usage steps occur. This preliminary structural preparation ensures that stress distribution is optimized in advance, preventing cracking and delamination before they can occur during later fabrication or use.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If uniform metal pad shapes are used, then deposition can be performed, but stress concentrations occur around metal pads causing delamination

Engineering Contradiction:

Improvedeposition uniformityVSAvoidattachment stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The metal pad is divided into multiple stepped levels rather than forming a single continuous structure. This segmentation creates multiple interfaces that distribute stress more evenly, preventing stress concentration at any single location and eliminating the root cause of cracking and delamination in high stress regions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the metal pad structure are given different heights and positions through the stepped configuration. This creates local variations in the metal pad geometry that are specifically designed to distribute stress evenly across different areas, with each step providing localized stress relief in high stress regions while maintaining overall structural integrity.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20250022825A1Seal ring structure and method of forming same

Publication Date: 2025.01.16 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

In an embodiment, a method includes: forming active devices over a semiconductor substrate; forming an interconnect structure over the active devices, the interconnect structure comprising a first portion of a seal ring over the semiconductor substrate, the seal ring being electrically insulated from the active devices; forming a first passivation layer over the interconnect structure; forming a first metal pad and a second metal pad extending through the first passivation layer and over the interconnect structure, the first metal pad having a bowl shape, the second metal pad having a step shape; and depositing a second passivation layer over the first metal pad and the second metal pad.