Interposer-Based 3D Microelectronic Assembly for Low-Impedance Interconnects

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Solution Overview

Problem

Conventional through-silicon vias (TSVs) reduce the available space on semiconductor chips for active circuitry, increasing silicon requirements and costs, particularly in compact portable devices where numerous chips with many input/output connections need efficient interconnection with low impedance.

Innovation Solution

A microelectronic assembly using an interposer with a coefficient of thermal expansion less than 10 ppm/°C, featuring conductive elements extending through the interposer to connect microelectronic elements, allowing for reduced chip thickness and efficient heat transfer while maintaining low impedance interconnects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional through-silicon vias (TSVs) are used to provide electrical connections between front and rear chip surfaces, then electrical connectivity is achieved, but the available space on the first face for active circuitry is reduced

Engineering Contradiction:
Improveelectrical connectivityVSAvoidavailable space for active circuitry
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent transitions from planar (2D) bond pad arrangements to three-dimensional (3D) stacked architectures with vertical interconnections. By stacking multiple active chips vertically and providing electrical connections between front and rear surfaces through the interposer, the design achieves high-density interconnection while preserving lateral bond pad space for active circuitry.

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

Solution Approach 2:

The patent introduces an interposer as an intermediary component between stacked microelectronic elements. The interposer provides through-silicon via (TSV) interconnections that penetrate vertically through the assembly, enabling electrical connectivity between front and rear chip surfaces while the bond pads remain on the lateral surfaces of the active chips, thus preserving active circuitry space.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Volume of moving object

If numerous chips are packed into a small space for compact portable devices, then device compactness is improved, but heat dissipation becomes more difficult

Engineering Contradiction:
Improvedevice sizeVSAvoidheat dissipation
Core Design Contradiction:
Volume of moving objectVSTemperature

Solution Approach 1:

The interposer serves as a thermal intermediary component with high thermal conductivity, positioned between stacked chips to facilitate heat transfer. The through-silicon via structures in the interposer provide thermal pathways that conduct heat away from the densely packed chips, enabling effective heat dissipation in compact three-dimensional arrangements.

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

Enables compact, high-density chip arrangements with reduced silicon usage and improved heat transfer, enhancing the performance and efficiency of complex portable devices and data servers by minimizing signal propagation delays and power consumption.

Implementation Method 1

an interposer of a material having a coefficient of thermal expansion less than 10 parts per million/°C

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP2647046B1Stacked microelectronic assembly having interposer connecting active chips
Publication Date: 2020.11.18 TESSERA INC
  • EP2647046B1 patent drawingFigure 1~2
  • EP2647046B1 patent drawingFigure 1A~3
  • EP2647046B1 patent drawingFigure 4~5

AI summary

A microelectronic assembly (100) can include first and second microelectronic elements (102, 112) each embodying active semiconductor devices adjacent a front surface (104, 114) thereof, and an interposer (120) of a material having a CTE less than 10 ppm/°C. Each microelectronic element (102, 112) can have a conductive pad (106, 116) exposed at the respective front surface (104, 114). The interposer (120) can have a second conductive element (118) extending within an opening (222) in the interposer and exposed at first and second surfaces (227, 229) of the interposer. The first and second surfaces (227, 229) can face the front surface (104, 114) of the respective first and second microelectronic elements (102, 112). Each microelectronic element (102, 112) can include a first conductive element (236, 238) extending within an opening (206, 216) extending from a rear surface (237, 239) towards the front surface (104, 114) of the respective microelectronic element. At least one of the first conductive elements (236, 238) can extend through the conductive pad (204, 214) of the respective first or second microelectronic element (102, 112).