IC Bonding Structure With Capping Layer Against Galvanic Corrosion

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Solution Overview

Problem

In the formation of 3D packages, existing bonding technologies face challenges in preventing galvanic corrosion of metal pads during the bonding process, which can damage the integrity of the diffusion barrier and affect the reliability of the bonding structure.

Innovation Solution

The formation of a capping layer over the metal pad, followed by a wet pre-cleaning process and optional sputtering to remove the exposed portion of the capping layer, prevents galvanic corrosion by protecting the metal pad from chemical exposure and ensures the integrity of the diffusion barrier.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If direct metal-to-metal bonding or hybrid bonding is performed, then bonding of package components is achieved, but galvanic corrosion of metal pads occurs during the bonding process

Engineering Contradiction:

Improvebonding reliabilityVSAvoidgalvanic corrosion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A capping layer is introduced as an intermediary between the metal pad and the bonding interface. This capping layer acts as a protective mediator that prevents direct contact between dissimilar metals during bonding, thereby eliminating the galvanic corrosion pathway while still allowing the bonding process to proceed effectively.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The capping layer is formed over the metal pad before the bonding process begins. This preliminary protective action ensures that the metal pad is already shielded from galvanic corrosion before any bonding operations occur, preventing the harmful effect rather than attempting to address it after the fact.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If wet pre-cleaning process is performed to clean the bonding surface, then cleaning effectiveness is improved, but chemical exposure may cause galvanic corrosion of metal pads

Engineering Contradiction:

Improvesurface cleanlinessVSAvoidgalvanic corrosion

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The capping layer serves as a protective intermediary during the wet pre-cleaning process. It allows the chemical cleaning solution to effectively clean the bonding surface while preventing the chemicals from contacting and corroding the metal pad, thus maintaining both cleaning effectiveness and metal pad integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The capping layer is formed before the wet pre-cleaning process, providing preliminary protection to the metal pad. This ensures that when chemicals are applied during cleaning, the metal pad is already shielded and cannot undergo galvanic corrosion even if chemicals come into contact with the bonding area.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If diffusion barrier integrity is compromised due to galvanic corrosion, then bonding structure reliability deteriorates

Engineering Contradiction:

Improvebonding structure reliabilityVSAvoiddiffusion barrier integrity

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The capping layer acts as a protective intermediary that prevents galvanic corrosion from occurring in the first place. By blocking the electrochemical reaction pathway between dissimilar metals, it preserves the diffusion barrier's integrity and prevents the chain reaction that would lead to bonding structure failure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The capping layer provides beforehand protection against galvanic corrosion, cushioning the diffusion barrier from potential damage. This preventive measure ensures that the diffusion barrier maintains its integrity throughout the bonding process and beyond, preventing reliability issues before they can manifest.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 approach effectively avoids galvanic corrosion of the metal pads, maintaining the integrity of the diffusion barrier and enhancing the reliability of the bonding structure in 3D packages.

Implementation Method 1

prevents galvanic corrosion by protecting the metal pad from chemical exposure

Methodology Applied

Scientific EffectGalvanic corrosion prevention:

Implementation Method 2

optional sputtering to remove the exposed portion of the capping layer

Methodology Applied

Scientific EffectSputtering: Sputtering

Data Source

PatentUS20240371804A1Bonding structures of integrated circuit devices and method forming the same

Publication Date: 2024.11.07 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method includes forming a conductive pad over an interconnect structure of a wafer, forming a capping layer over the conductive pad, forming a dielectric layer covering the capping layer, and etching the dielectric layer to form an opening in the dielectric layer. The capping layer is exposed to the opening. A wet-cleaning process is then performed on the wafer. During the wet-cleaning process, a top surface of the capping layer is exposed to a chemical solution used for performing the wet-cleaning process. The method further includes depositing a conductive diffusion barrier extending into the opening, and depositing a conductive material over the conductive diffusion barrier.