Low-k Interlevel Dielectric Cap Layer Against CMP Damage

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Solution Overview

Problem

Low-k dielectric materials in semiconductor devices are prone to damage during processing, leading to leakage paths that reduce electrical performance.

Innovation Solution

A cap layer with a specific carbon atom content range is introduced to provide improved hardness and damage resistance, reducing surface dishing and residue, and enhancing the electrical performance by minimizing leakage current and RC delay.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If low-k dielectric materials are used to reduce RC delay, then electrical performance is improved, but damage resistance during processing deteriorates

Engineering Contradiction:

Improveelectrical performanceVSAvoiddamage resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

A cap layer is introduced as an intermediary protective layer between the polishing pad and the low-k dielectric layer. This cap layer absorbs the mechanical stress and damage during chemical mechanical polishing, preventing direct contact between the polishing tools and the vulnerable low-k dielectric material, thus resolving the contradiction between maintaining electrical performance and improving damage resistance

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cap layer is formed beforehand on the low-k dielectric layer to provide cushioning protection before the polishing process begins. This pre-protective measure ensures that the low-k dielectric material is shielded from potential damage during subsequent processing steps, allowing the low-k material to maintain its electrical performance while gaining damage resistance

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If low-k dielectric materials are used to reduce RC delay, then electrical performance is improved, but surface dishing occurs during polishing

Engineering Contradiction:

Improveelectrical performanceVSAvoidsurface flatness

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The cap layer serves as a sacrificial intermediary that absorbs the polishing action, preventing direct mechanical contact between the polishing pad and the low-k dielectric layer. This mediation eliminates the surface dishing problem while allowing the low-k dielectric material to maintain its excellent electrical performance characteristics

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If low-k dielectric materials are used to reduce RC delay, then electrical performance is improved, but metal residue accumulates during processing

Engineering Contradiction:

Improveelectrical performanceVSAvoidmetal residue

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The cap layer acts as a protective barrier that prevents metal particles from contaminating the low-k dielectric layer during processing. By providing this intermediate protective layer, metal residue is prevented from accumulating on the low-k dielectric material, thus maintaining both electrical performance and process cleanliness

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12604725B2Interlevel dielectric structure in semiconductor device

Publication Date: 2026.04.14 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A semiconductor device including a substrate, a low-k dielectric layer, a cap layer, and a conductive layer is provided. The low-k dielectric layer is disposed over the substrate. The cap layer is disposed on the low-k dielectric layer, wherein a carbon atom content of the cap layer is greater than a carbon atom content of the low-k dielectric layer. The conductive layer is disposed in the cap layer and the low-k dielectric layer.