Bi-Layer Protection Layer for Wafer Bonding Oxidation

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Solution Overview

Problem

The challenge in integrated circuit packaging is the degradation of low-k dielectric layers and metal features due to oxidation, which is not effectively addressed by existing technologies, leading to device performance issues.

Innovation Solution

A bi-layer protection layer comprising a non-oxygen-containing layer, such as silicon nitride, and an oxygen-containing layer, such as silicon oxide, is formed on the sidewalls of the device wafer to prevent oxidation and moisture ingress, thereby reducing the oxidation of low-k dielectric layers and metal features during the packaging process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single-layer protection layer is formed on the device wafer sidewall, then the manufacturing process is simple, but it cannot effectively prevent oxidation of low-k dielectric layers and metal features

Engineering Contradiction:

Improveprotection against oxidationVSAvoidprotection layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The protection layer is segmented into multiple sub-layers with different materials and functions. The first sub-layer (non-oxygen-containing) provides immediate oxidation barrier, while the second sub-layer (oxygen-containing) provides moisture barrier and stress management. This segmentation allows each layer to specialize in preventing specific degradation mechanisms that a single layer cannot address alone.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The protection layer uses composite material structure combining different dielectric materials with complementary properties. The non-oxygen-containing material (e.g., silicon nitride) prevents oxygen diffusion, while the oxygen-containing material (e.g., silicon oxide) prevents moisture ingress and provides mechanical stability. This composite approach creates synergistic protection against both oxidation and moisture-related degradation.

Inventive Principle:

Principle #40Composite materials

2Reliability

If oxygen-containing materials are used in the protection layer, then moisture isolation is improved, but oxidation of low-k dielectric layers and metal features occurs

Engineering Contradiction:

Improvemoisture isolationVSAvoidoxidation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The protection function is segmented between two sub-layers: the first sub-layer (non-oxygen-containing) specifically addresses oxidation prevention by blocking oxygen diffusion pathways, while the second sub-layer (oxygen-containing) handles moisture isolation. This functional segmentation allows each layer to excel at its specific protective role without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first sub-layer acts as an intermediary barrier between the oxygen-containing second sub-layer and the underlying low-k dielectric layers and metal features. It mediates the potential harmful interaction by blocking oxygen from reaching sensitive structures, while still allowing the second sub-layer to provide its moisture isolation function.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 bi-layer protection layer effectively isolates the device wafer from oxygen and moisture, preventing degradation and enhancing the reliability and performance of the integrated circuit packaging by reducing warpage and improving bonding strength.

Implementation Method 1

a first sub layer 62A formed of a first material comprising a non-oxygen-containing material... the first sub layer 62A having a lower oxygen atomic percentage than the second sub layer 62B

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 2

The bi-layer protection layer effectively isolates the device wafer from oxygen and moisture, preventing degradation

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentUS20230154765A1Oxygen-Free Protection Layer Formation in Wafer Bonding Process

Publication Date: 2023.05.18 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method includes bonding a first wafer to a second wafer, and performing a trimming process on the first wafer. An edge portion of the first wafer is removed. After the trimming process, the first wafer has a first sidewall laterally recessed from a second sidewall of the second wafer. A protection layer is deposited and contacting a sidewall of the first wafer, which deposition process includes depositing a non-oxygen-containing material in contact with the first sidewall. The method further includes removing a horizontal portion of the protection layer that overlaps the first wafer, and forming an interconnect structure over the first wafer. The interconnect structure is electrically connected to integrated circuit devices in the first wafer.