Stacked Transistor Bonding With Shallow Plasma-Activated Isolation

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Solution Overview

Problem

Existing bonding techniques for stacked transistor structures face challenges in forming reliable insulation layers due to seam formation and etchant damage, particularly in advanced IC technology nodes, which can degrade performance and reliability.

Innovation Solution

Implementing plasma activated wafer bonding with controlled shallow plasma activation and dielectric layers, such as SiCN or SiN, to ensure the underlying superlattice structure is not impacted, and using a separate barrier layer to prevent H2O diffusion and oxidation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional bonding techniques are used for stacked transistor structures, then the manufacturing process is simpler, but seam formation and etchant damage occur that degrade reliability

Engineering Contradiction:

Improvebonding reliabilityVSAvoidbonding process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by performing plasma activation on the bonding surfaces before the actual bonding process. This pre-treatment modifies the surface chemistry to enhance bonding quality and prevent seam formation, thereby improving reliability without requiring fundamental changes to the bonding process architecture

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs parameter changes by carefully controlling plasma activation parameters (power, time, gas composition) and bonding parameters (temperature, pressure, alignment precision). These parameter optimizations enable high-quality bonding that prevents seam formation and etchant damage while maintaining process feasibility

Inventive Principle:

Principle #35Parameter changes

2Reliability

If plasma activated wafer bonding is used, then seam formation and etchant damage are prevented, but the process complexity increases

Engineering Contradiction:

Improvestacked transistor reliabilityVSAvoidbonding process ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent uses plasma activation as an intermediary step that mediates between the bonding surfaces. This intermediate treatment creates optimal surface conditions for bonding, preventing direct contact issues like seam formation and etchant damage while adding a controlled, repeatable process step

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If deep plasma activation is used, then bonding surface preparation is more thorough, but the underlying superlattice structure is damaged

Engineering Contradiction:

Improvebonding surface qualityVSAvoidsuperlattice structure damage

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by concentrating the plasma activation effect specifically at the bonding surfaces while protecting the underlying superlattice structure. This is achieved through precise control of plasma parameters and exposure time, ensuring surface preparation quality without causing bulk material damage

Inventive Principle:

Principle #3Local quality

4Reliability

If barrier layers are added to prevent H2O diffusion, then oxidation is prevented, but device structure becomes more complex

Engineering Contradiction:

Improveoxidation resistanceVSAvoidlayer structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies universality by designing barrier layers that serve multiple functions: preventing H2O diffusion, providing mechanical support, and maintaining structural integrity. This multi-functionality approach prevents oxidation while minimizing the addition of structural complexity, as the same layers perform multiple protective roles

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 reliability and performance of stacked transistor structures by preventing seam formation and etchant damage, ensuring the integrity of the underlying superlattice structure and channel layer.

Implementation Method 1

performing a plasma activation process to a first bonding surface of the first insulation layer and a second bonding surface of the second insulation layer to form a first plasma activated surface and a second plasma activated surface, respectively

Methodology Applied

Scientific EffectPlasma activation: Plasma

Data Source

PatentUS20250349818A1Bonding techniques for stacked transistor structures

Publication Date: 2025.11.13 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Bonding techniques for stacked device structures are disclosed herein. An exemplary method includes forming a first insulation layer on a first device component and a second insulation layer on a second device component. A plasma activation process is performed to the first insulation layer and the second insulation layer. After the plasma activation process, an upper portion of the first insulation layer and the second insulation layer includes a plasma activated layer and a lower portion of the first insulation layer and the second insulation layer includes a barrier layer. The plasma activated layers of respective ones of the first insulation layer and the second insulation layer are bonded to form a stacked structure that includes the first device component over the second device component. The first insulation layer bonded to the second insulation layer forms an isolation structure between the first device component and the second device component.