Interconnect Air Gap Structure for Lower Capacitive Coupling

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Solution Overview

Problem

As semiconductor devices become more densely integrated, the reduced spacing between conductive features leads to increased capacitive coupling, resulting in higher power consumption and RC time constants, which existing technologies struggle to address effectively.

Innovation Solution

The introduction of air gaps between conductive features, formed by decomposing a sacrificial polymer layer using UV energy, reduces capacitive coupling and maintains structural integrity through a support layer and dielectric fill, while using graphene and etch stop layers to prevent material intrusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the distance between conductive features is reduced to increase device density, then device integration density is improved, but capacitive coupling between conductive features increases

Engineering Contradiction:

Improvedevice integration densityVSAvoidcapacitive coupling

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

An air gap is introduced as an intermediary layer between adjacent conductive features. This air gap acts as a mediator that reduces the capacitive coupling between conductors while allowing the features to remain in close proximity for high density integration. The air gap has a lower dielectric constant than traditional insulating materials, thereby reducing the capacitance between adjacent conductive elements.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The dielectric parameter (k-value) between conductive features is changed from a solid insulating material to an air gap with k≈1. This parameter change significantly reduces the capacitive coupling between adjacent conductors while maintaining the physical spacing required for high-density integration, thus resolving the contradiction between density and capacitive coupling.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If air gaps are introduced to reduce capacitive coupling, then power consumption is reduced, but structural integrity may be compromised

Engineering Contradiction:

Improvepower consumptionVSAvoidstructural integrity

Core Design Contradiction:

Loss of energyVSStrength

Solution Approach 1:

A support layer is formed beforehand to provide mechanical strength and structural support to the air gap structure. This support layer prevents the air gap from collapsing during subsequent processing steps and device operation, thereby maintaining structural integrity while allowing the air gap to function in reducing capacitive coupling and power consumption.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The structure combines multiple materials with different properties: the air gap for electrical isolation and low capacitance, and the support layer (typically a dielectric material) for mechanical strength. This composite structure resolves the contradiction by allowing each material to fulfill its specific function - the air gap reduces power consumption while the support layer maintains structural integrity.

Inventive Principle:

Principle #40Composite materials

3Reliability

If air gaps are formed by decomposing sacrificial polymer layer, then capacitive coupling is minimized, but manufacturing process complexity increases

Engineering Contradiction:

Improvecapacitive coupling reductionVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A sacrificial polymer layer is deposited in advance in the regions where air gaps are desired. This preliminary action simplifies the subsequent air gap formation process, as the sacrificial layer can be selectively removed through decomposition to create the air gaps. This approach is simpler than attempting to directly create air gaps through complex etching or deposition processes.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The mechanical process of forming air gaps through physical removal or deposition is replaced by a chemical decomposition process. The sacrificial polymer layer is decomposed (typically through thermal or chemical means) to create the air gaps, which is a simpler and more controllable process than mechanical removal methods, thereby reducing manufacturing complexity while achieving the desired capacitive coupling reduction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 effectively minimizes capacitive coupling, reduces power consumption, and enhances the reliability of semiconductor devices by preventing line-to-line leakage and maintaining electrical integrity.

Implementation Method 1

formed by decomposing a sacrificial polymer layer using UV energy

Methodology Applied

Scientific EffectUV decomposition: Photodissociation

Data Source

PatentUS20250323095A1Semiconductor device structure having air gap and methods of forming the same

Publication Date: 2025.10.16 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

An interconnect structure is provided. The structure includes a dielectric layer, a first etch stop layer disposed over the dielectric layer, a capping layer disposed between the dielectric layer and the first etch stop layer, the first etch stop layer and the capping layer confining an air gap therein, a first conductive layer disposed over the dielectric layer and immediately adjacent to the capping layer, and a barrier layer disposed between the conductive layer and the capping layer.