Semiconductor Die Stack Without Spacer Layers

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Solution Overview

Problem

Conventional die stacking methods are costly and complex due to the use of conductive spacer layers, which increase assembly process steps and packaging costs, and do not effectively facilitate heat dissipation or electrical connections between stacked dies.

Innovation Solution

The method eliminates spacer layers by using large conductive die receiving areas on the host die to directly establish electrical and thermal connections with stacked dies via conductive die attachment materials, reducing package size and manufacturing costs while enabling improved heat dissipation and eliminating the need for wire bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conductive spacer layers are used between stacked dies, then electrical connections can be established, but assembly process complexity and packaging costs increase

Engineering Contradiction:
Improveelectrical connectionVSAvoidassembly process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the conductive spacer layer from the die stacking structure, eliminating the need for this intermediate component. The host die's conductive receiving area directly contacts the stacked die, extracting the spacer function and simplifying the assembly process while maintaining electrical connection capability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the electrical connection function and mechanical support function into a single interface. The conductive receiving area on the host die simultaneously provides electrical connection and structural support, eliminating the separate spacer layer that previously performed these functions

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If conductive spacer layers are used between stacked dies, then electrical connections can be established, but manufacturing costs increase

Engineering Contradiction:
Improveelectrical connectionVSAvoidpackaging cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts and eliminates the conductive spacer layer, removing the associated material costs and manufacturing steps. The direct contact between the host die's conductive receiving area and the stacked die reduces component count and assembly complexity, thereby lowering packaging costs

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent utilizes the host die's existing conductive receiving area, which is already part of the host die structure, rather than adding a separate expensive spacer layer. This approach uses an existing structure for its intended purpose, avoiding additional material and manufacturing costs

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Reliability

If conventional die stacking methods are used, then dies can be stacked, but heat dissipation is not effectively facilitated

Engineering Contradiction:
Improvedie stackingVSAvoidheat dissipation
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent merges the electrical connection function and thermal conduction function into the same interface. The conductive receiving area on the host die serves dual purposes: establishing electrical connection and facilitating heat dissipation from the stacked die, eliminating the thermal barrier that spacer layers would create

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The conductive receiving area acts as an intermediary that facilitates thermal energy transfer from the stacked die to the host die. This mediator structure provides a direct thermal pathway, improving heat dissipation efficiency compared to spacer layer approaches

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

This approach results in reduced package size, lower manufacturing costs, enhanced heat dissipation, and direct electrical connections between stacked dies, improving the overall efficiency and performance of semiconductor device packaging.

Implementation Method 1

improved heat dissipation due to thermal conductivity between stacked dies

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

direct electrical connections between stacked dies

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP2272075B1Semiconductor die stack
Publication Date: 2021.03.10 QUALCOMM INC
  • EP2272075B1 patent drawingFigure 1~2
  • EP2272075B1 patent drawingFigure 3~4
  • EP2272075B1 patent drawingFigure 5~6

AI summary

Die stacking systems and methods are disclosed. In an embodiment, a die has a surface that includes a passivation area, at least one conductive bond pad area, and a conductive stacked die receiving area sized to receive at least a second die.