Chip Package Protection Layer for Nickel Oxidation During Deflux

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Solution Overview

Problem

Existing semiconductor chip packaging technologies face challenges in protecting the nickel-containing layer from deflux solutions during the removal of flux layers, leading to potential migration and oxidation of nickel atoms, which affects the adhesion and integrity of conductive bumps.

Innovation Solution

A conductive protection layer made of a denser material, such as tin or its alloy, is formed over the nickel-containing layer to prevent contact with deflux solutions, and an intermetallic compound layer is formed during a reflow process to enhance adhesion, thereby strengthening the connection between pads and conductive bumps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the nickel-containing layer is directly exposed to deflux solutions during flux layer removal, then the deflux solution can effectively remove flux, but the nickel atoms migrate and oxidize, reducing adhesion and integrity of conductive bumps

Engineering Contradiction:

Improveflux layer removalVSAvoidadhesion and integrity of conductive bumps

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

A conductive protection layer made of tin or its alloy is introduced as an intermediary between the nickel-containing layer and the deflux solution. This protection layer prevents direct contact between the nickel and the deflux solution, thereby preventing nickel migration and oxidation while still allowing the deflux solution to remove the flux layer effectively.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The conductive protection layer is formed over the nickel-containing layer before the deflux solution is applied. This preliminary protective action ensures that the nickel layer is already shielded when the deflux process begins, preventing any potential nickel migration or oxidation during flux removal.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a conductive protection layer is formed over the nickel-containing layer, then nickel migration and oxidation are prevented, but an additional manufacturing step is required

Engineering Contradiction:

Improveprotection from nickel migration and oxidationVSAvoidnumber of manufacturing steps

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The conductive protection layer is formed using the same electroplating process that is already used to form the conductive bumps. By merging the protection layer formation with the existing electroplating step, the patent adds necessary protection without significantly increasing manufacturing complexity or requiring entirely new process equipment.

Inventive Principle:

Principle #5Merging (Combining)

3Strength

If an intermetallic compound layer is formed during reflow process, then adhesion between pads and conductive bumps is enhanced, but the reflow process temperature and time must be precisely controlled

Engineering Contradiction:

Improveadhesion between pads and conductive bumpsVSAvoidcontrol of reflow process parameters

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The reflow process parameters (temperature and time) are specifically optimized to control the formation of the intermetallic compound layer. By carefully adjusting these parameters, the patent ensures that the intermetallic layer forms with the right thickness and properties to enhance adhesion, while avoiding excessive growth that could cause brittleness or other defects.

Inventive Principle:

Principle #35Parameter changes

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 conductive protection layer and intermetallic compound layer effectively shield the nickel-containing layer from deflux solutions, improving the adhesion and yield of the chip bonding process by preventing nickel migration and oxidation, thus enhancing the reliability of the chip package structure.

Implementation Method 1

A conductive protection layer made of a denser material, such as tin or its alloy, is formed over the nickel-containing layer to prevent contact with deflux solutions

Methodology Applied

Scientific EffectPhysical barrier protection:

Implementation Method 2

an intermetallic compound layer is formed during a reflow process to enhance adhesion, thereby strengthening the connection between pads and conductive bumps

Methodology Applied

Scientific EffectIntermetallic compound formation: Chemical Bonding

Data Source

PatentUS20250323139A1Chip package structure with protection element

Publication Date: 2025.10.16 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A chip package structure is provided. The chip package structure includes. The chip package structure includes a first wiring substrate including a substrate, a first pad, a second pad, and an insulating layer. The chip package structure includes a chip bonded to the second pad. The chip package structure includes a nickel-containing layer under the first pad. The chip package structure includes. a conductive protection layer under the nickel-containing layer. The conductive protection layer has a curved bottom surface, the curved bottom surface is higher than a bottom surface of the insulating layer, and the curved bottom surface and the bottom surface face away from the substrate.