Composite Dielectric Bonding Layer for Void-Tolerant Die Stacking

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In semiconductor packages, the stacking of dies with bond wires increases height and introduces signal delays due to voids formed at the bonding interface, which can lead to weakened bonding strength, high resistance in interconnects, and electrical shorts, requiring an ultra-clean environment that increases manufacturing costs.

Innovation Solution

The implementation of a composite dielectric structure with a flexible polymer layer that conforms to irregularities at the bonding interface, reducing void formation and enhancing bonding strength through a chemical vapor deposition process using siloxane derivatives, allowing for lenient cleaning conditions and improved interconnect reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If bond wires are used to connect semiconductor dies in a stacked configuration, then electrical connections between dies are established, but the package height increases and signal propagation delays are introduced

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidpackage height

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The patent removes bond wires from the system entirely by implementing direct die-to-die bonding. The bonding interface directly connects conductive components between adjacent dies without intermediate wire connections, thereby eliminating the height contribution and signal delays associated with bond wires while maintaining electrical connectivity.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If conventional bonding processes are used without a flexible dielectric layer, then the bonding process is simpler, but voids form at the bonding interface leading to weakened bonding strength and potential electrical shorts

Engineering Contradiction:

Improvebonding strengthVSAvoiddielectric structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces a flexible dielectric layer comprising polymer material that can deform to conform to surface irregularities at the bonding interface. This flexible layer fills gaps and accommodates topography variations, preventing void formation and ensuring complete contact between bonding surfaces, thereby enhancing bonding strength and preventing electrical shorts.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The dielectric structure is configured as a composite with multiple layers including a flexible polymer layer and a rigid dielectric layer. This composite structure combines the conformability and void-prevention capabilities of the flexible polymer material with the structural support and electrical insulation properties of the rigid dielectric material, achieving both reliability and functional requirements.

Inventive Principle:

Principle #40Composite materials

3Reliability

If strict cleaning conditions are imposed to prevent void formation, then bonding quality improves, but manufacturing costs increase

Engineering Contradiction:

Improvebonding qualityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The flexible dielectric layer acts as a preventive measure that compensates for surface irregularities and contamination before they can cause bonding defects. By incorporating this compliant layer, the process tolerates less stringent cleaning conditions because the flexible material absorbs the impact of minor surface imperfections, preventing void formation without requiring ultra-clean manufacturing environments.

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 solution enhances bonding strength, reduces interconnect resistance, and minimizes the risk of electrical shorts, while reducing manufacturing costs by allowing for less stringent cleaning requirements during the bonding process.

Implementation Method 1

a third dielectric layer between the first and second dielectric layers, the third dielectric layer configured to conform to one or more irregularities at the second side

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a composite dielectric structure with a flexible polymer layer that conforms to irregularities at the bonding interface, reducing void formation and enhancing bonding strength through a chemical vapor deposition process using siloxane derivatives

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Data Source

PatentUS11862607B2Composite dielectric structures for semiconductor die assemblies and associated systems and methods

Publication Date: 2024.01.02 MICRON TECHNOLOGY INC

AI summary

Composite dielectric structures for semiconductor die assemblies, and associated systems and methods are disclosed. In some embodiments, the composite dielectric structure includes a flexible dielectric layer configured to conform to irregularities (e.g., particles, defects) at a bonding interface of directly bonded semiconductor dies (or wafers). The flexible dielectric layer may include a polymer material configured to deform in response to localized pressure generated by the irregularities during bonding process steps. The composite dielectric structure includes additional dielectric layers sandwiching the flexible dielectric layer such that the composite dielectric structure can provide robust bonding strength to other dielectric layers through the additional dielectric layers. In some embodiments, a chemical vapor deposition process may be used to form the composite dielectric structure utilizing siloxane derivatives as a precursor.