Conformal Coatings for Die-to-Wafer Self-Alignment Bonding

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Solution Overview

Problem

Current die stacking techniques, such as hybrid bonding, face challenges in maintaining precise alignment and pitch between integrated circuit dies due to the removal of hydrophobic materials during pre-bond processing, which affects the assembly of 3D die stacks.

Innovation Solution

A conformal protective layer is applied on the sidewalls of hybrid bonding regions to shield them from pre-bond processing, followed by a selective application of a hydrophobic coating that confines liquid droplets during bonding, ensuring precise alignment and protection of the bonding regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pre-bond processing is performed to prepare hybrid bonding regions, then bonding quality is improved, but hydrophobic materials are removed

Engineering Contradiction:

Improvebonding qualityVSAvoidhydrophobic material removal

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

A conformal protective layer is deposited over the hydrophobic material before pre-bond processing occurs. This protective layer shields the hydrophobic material from damage during plasma treatment or other preparatory steps, allowing the hydrophobic material to remain intact for subsequent self-alignment bonding operations

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The conformal protective layer acts as an intermediary barrier between the pre-bond processing environment and the hydrophobic material. It allows necessary processing to occur while preventing direct contact between harmful processing conditions and the hydrophobic material that enables self-alignment

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If hydrophobic materials are removed, then pre-bond processing can be completed, but self-alignment precision deteriorates

Engineering Contradiction:

Improvepre-bond processing completionVSAvoidself-alignment precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The conformal protective layer is applied in advance to preserve the hydrophobic material's surface properties. By protecting the hydrophobic material before bonding, the material maintains its ability to guide liquid droplets for precise self-alignment while still allowing pre-bond processing to proceed

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The protective layer is selectively removed or patterned to expose hydrophobic material only in the desired bonding regions. This allows pre-bond processing to be completed on protected areas while maintaining self-alignment capabilities in exposed hydrophobic regions

Inventive Principle:

Principle #2Taking out (Extraction)

3Area of moving object

If bond pitch is reduced, then die stacking density is improved, but alignment difficulty increases

Engineering Contradiction:

Improvedie stacking densityVSAvoidalignment difficulty

Core Design Contradiction:

Area of moving objectVSDifficulty of detecting and measuring

Solution Approach 1:

The hydrophobic material creates self-alignment through liquid droplet confinement, allowing the bonding system to self-correct alignment errors automatically. This self-alignment mechanism enables precise bonding at reduced pitch without requiring complex external alignment systems

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Hydrophobic material is applied selectively to specific bonding regions with precise spatial distribution. This local hydrophobic patterning creates localized liquid droplet confinement zones that guide self-alignment precisely where needed, enabling accurate bonding even at reduced pitch distances

Inventive Principle:

Principle #3Local quality

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 enhances the precision and reliability of die-to-wafer bonding by maintaining the integrity of hydrophobic structures, allowing for high-accuracy self-alignment and reduced bond pitches, thereby improving the assembly of 3D die stacks.

Implementation Method 1

a selective application of a hydrophobic coating that confines liquid droplets during bonding

Methodology Applied

Scientific EffectHydrophobic interaction: Hydrophobe

Implementation Method 2

A conformal protective layer is applied on the sidewalls of hybrid bonding regions to shield them from pre-bond processing

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentUS20250112155A1Conformal coatings with spatially defined surface energies for die-to-wafer self-alignment assisted assembly

Publication Date: 2025.04.03 INTEL CORP

AI summary

Hybrid bonded die stacks, related apparatuses, systems, and methods of fabrication are disclosed. One or both of an integrated circuit (IC) die hybrid bonding region and a base substrate hybrid bonding region are surrounded by a protective layer and hydrophobic structures on the protective layer. The protective layer is formed prior to pre-bond processing to protect the hybrid bonding region during plasma activation, clean test, high temperature processing, or the like. Immediately prior to bonding, the hydrophobic structures are selectively applied to the protective layer. The hybrid bonding regions are brought together with a liquid droplet therebetween, and capillary forces cause the IC die to self-align. A hybrid bond is formed by evaporating the droplet and a subsequent anneal. The hydrophobic structures contain the liquid droplet for alignment during bonding.