CMP Pad Texture for Planarization and Defect Control

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Solution Overview

Problem

Conventional chemical mechanical polishing (CMP) pads suffer from suboptimal contact area with the workpiece, leading to surface and sub-surface damage, and require frequent conditioning due to non-reproducible microstructure and wear issues, compromising both planarization efficiency and defectivity.

Innovation Solution

A CMP pad with a three-dimensional reticulated network polishing texture, featuring a specific dimensionless roughness (R) between 0.01 and 0.75, which maintains consistent contact area and reduces the need for conditioning by distributing shear and heating, combining stiffness for planarization with compliance for low defectivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional CMP pads use traditional polishing surfaces, then polishing operation is simple, but real contact area is small leading to surface and sub-surface damage

Engineering Contradiction:

Improvepolishing operation simplicityVSAvoidsurface quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The polishing surface is segmented into multiple discrete polishing elements (protrusions, asperities, or domes) distributed across the pad surface. Each element acts as an independent contact point, collectively providing sufficient real contact area to prevent surface and sub-surface damage while maintaining manufacturing simplicity through modular structure

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The polishing pad incorporates regions with different properties: a compliant layer closer to the workpiece for conformal contact and defect reduction, and a stiffer support layer for structural integrity and planarization efficiency. This local differentiation resolves the contradiction between contact area and manufacturing simplicity

Inventive Principle:

Principle #3Local quality

2Device complexity

If conventional CMP pads use traditional microstructures, then pad structure is simple, but microstructure is non-reproducible requiring frequent conditioning

Engineering Contradiction:

Improvepad structure complexityVSAvoidmicrostructure consistency

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The desired polishing microstructure is pre-formed during pad manufacturing rather than developed in-service. Polishing elements are created with controlled size, shape, and distribution before the pad enters service, ensuring reproducible microstructure that maintains consistent performance without frequent conditioning

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of allowing the polishing surface to wear and form texture over time (conventional approach), the invention inverts the sequence by pre-forming the texture during manufacturing. The pad starts with the desired microstructure and maintains it through its service life, eliminating the need for conditioning to create texture

Inventive Principle:

Principle #13The other way round (Inversion)

3Productivity

If CMP pad uses high stiffness for planarization, then planarization efficiency is high, but defectivity increases due to reduced compliance

Engineering Contradiction:

Improveplanarization efficiencyVSAvoiddefectivity

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The pad structure is differentiated into zones with different mechanical properties: a compliant layer near the workpiece interface that conforms to surface variations and reduces defectivity, and a stiffer support layer that provides structural integrity and enables effective planarization. This local property differentiation resolves the stiffness-compliance contradiction

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The polishing pad uses composite construction with multiple layers or phases having different mechanical properties. The combination of compliant and stiff materials allows the pad to simultaneously achieve high planarization efficiency through stiffness and low defectivity through compliance, resolving the contradiction between productivity and harmful factors

Inventive Principle:

Principle #40Composite materials

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

The solution enhances real contact area, reduces defect formation, and extends pad life by maintaining consistent polishing performance and reducing the need for periodic conditioning, while achieving both high planarization efficiency and low defectivity.

Implementation Method 1

maintains consistent contact area and reduces the need for conditioning by distributing shear and heating

Methodology Applied

Scientific EffectShear stress distribution: Shear Stress

Implementation Method 2

a three-dimensional reticulated network polishing texture

Methodology Applied

Scientific EffectMechanical structure stability: Mechanical Force

Data Source

PatentUS7530887B2Chemical mechanical polishing pad with controlled wetting

Publication Date: 2009.05.12 DUPONT ELECTRONIC MATERIALS HLDG INC

AI summary

Chemical mechanical polishing pads are provided, wherein the chemical mechanical polishing pads have a polishing layer comprising a polishing texture that exhibits a dimensionless roughness, R, is between 0.01 and 0.75. Also provided are methods of making the chemical mechanical polishing pads and for using them to polish substrates.