Self-Aligned TSV Solder Bumps for Dense 3D Interconnects

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Solution Overview

Problem

Existing semiconductor fabrication methods struggle to efficiently integrate through-substrate-vias (TSVs) and self-aligned solder bumps, which are crucial for high-performance interconnects and 3D packaging, often requiring complex and inefficient multilayered routing schemes.

Innovation Solution

A method involving an injection molded soldering process (IMS) is used to simultaneously form self-aligned solder bumps and through-substrate-vias, utilizing a superconducting metal for both, with the bumps aligned to the vias and coupled to a buried metallization layer, enabling efficient integration and alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If traditional multilayered routing schemes are used for signal paths, then routing complexity is reduced, but interconnect density and connection length are increased

Engineering Contradiction:
Improverouting complexityVSAvoidinterconnect density
Core Design Contradiction:
Device complexityVSVolume of moving object

Solution Approach 1:

The patent transitions from planar 2D routing to 3D vertical routing by implementing through-substrate vias that penetrate the substrate thickness. This dimensional change enables signals to travel vertically through the substrate rather than laterally across multiple layers, achieving higher interconnect density and shorter connection lengths while maintaining routing simplicity

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent segments the interconnect structure into distinct functional components: through-substrate vias for vertical signal transmission, solder bumps for chip-to-chip bonding, and embedded capacitors for signal integrity. This segmentation allows each component to be optimized independently while working together to reduce overall routing complexity

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If through-substrate-vias and solder bumps are formed separately, then manufacturing precision can be maintained, but device complexity and fabrication steps are increased

Engineering Contradiction:
Improvealignment precisionVSAvoidfabrication steps
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges the formation of through-substrate vias and solder bumps into a single integrated fabrication process. The same via structures serve dual purposes: as electrical interconnects and as alignment features for solder bump placement. This consolidation reduces fabrication steps while maintaining precision through self-alignment mechanisms

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The through-substrate via structures perform multiple functions simultaneously: providing electrical connectivity, serving as mechanical support, and acting as alignment references for solder bumps. This multi-functionality eliminates the need for separate alignment features, reducing device complexity while preserving manufacturing precision

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of manufacture

If conventional interconnect methods are used, then fabrication process is simpler, but connection length and signal path delay are increased

Engineering Contradiction:
Improvefabrication process simplicityVSAvoidconnection length
Core Design Contradiction:
Ease of manufactureVSLength of moving object

Solution Approach 1:

The patent exploits the third dimension (substrate thickness) to create direct vertical pathways for signals. By routing signals vertically through the substrate via TSVs rather than laterally across the chip surface, connection length is dramatically reduced while the fabrication process remains relatively simple and compatible with existing semiconductor manufacturing techniques

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 allows for high-density, short connection paths in 3D integrated circuits, enhancing chip performance and reliability by aligning solder bumps directly to TSVs, thus improving signal routing and mechanical attachment between chips.

Implementation Method 1

an injection molded soldering process (IMS) is used to simultaneously form self-aligned solder bumps and through-substrate-vias

Methodology Applied
Scientific EffectPhase change: Phase Change

Data Source

PatentEP3622555B1Through-substrate-vias with self-aligned solder bumps
Publication Date: 2026.01.21 INTERNATIONAL BUSINESS MACHINE CORPORATION
  • EP3622555B1 patent drawingFigure 1~3
  • EP3622555B1 patent drawingFigure 4~6
  • EP3622555B1 patent drawingFigure 7~9

AI summary

A semiconductor structure and methods of forming the semiconductor structure include a solder bump self-aligned to a through-substrate-via, wherein the solder bump and the through-substrate- via are formed of a conductive metal material, and wherein the through-substrate-via is coupled to a buried metallization layer, which is formed of a different conductive metal material.