CMP Polishing Pad Segmented Foundation and Surface Layers

Solution Overview

Problem

Conventional CMP polishing pads face a trade-off between across-wafer uniformity and within-die planarization, with hard pads offering good die-level planarization but poor wafer uniformity, and soft pads providing good wafer uniformity but poor die-level planarization, while also being prone to scratching and dishing. Additionally, existing approaches limit the decoupling of polishing surface and bulk properties, compromising defect characteristics and process uniformity.

Innovation Solution

The development of polishing pads with a distinct foundation layer and polishing surface layer, where the foundation layer is made of a stable, non-compressible material and the surface layer is softer, allowing for decoupling of properties to optimize both planarization performance and defect characteristics. This is achieved by using a harder foundation layer, such as polycarbonate, with a softer urethane surface layer, which reduces scratching and enhances adhesion and uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a hard polishing pad is used, then die-level planarization is improved, but across-wafer uniformity deteriorates and scratching increases

Engineering Contradiction:

Improvedie-level planarizationVSAvoidacross-wafer uniformity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The polishing pad is segmented into two distinct layers: a hard foundation layer (8-15 Shore D) for die-level planarization and a soft polishing surface layer (3-7 Shore D) for across-wafer uniformity. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between planarization precision and uniformity reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the polishing pad have different hardness properties tailored to their specific functions. The foundation layer is harder to provide structural support and die-level planarization, while the surface layer is softer to ensure across-wafer uniformity and reduce scratching. This local quality differentiation resolves the contradiction by optimizing each region for its specific purpose.

Inventive Principle:

Principle #3Local quality

2Reliability

If a soft polishing pad is used, then across-wafer uniformity is improved, but die-level planarization deteriorates

Engineering Contradiction:

Improveacross-wafer uniformityVSAvoiddie-level planarization

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The polishing pad is segmented into two distinct layers: a hard foundation layer (8-15 Shore D) for die-level planarization and a soft polishing surface layer (3-7 Shore D) for across-wafer uniformity. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between planarization precision and uniformity reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the polishing pad have different hardness properties tailored to their specific functions. The foundation layer is harder to provide structural support and die-level planarization, while the surface layer is softer to ensure across-wafer uniformity and reduce scratching. This local quality differentiation resolves the contradiction by optimizing each region for its specific purpose.

Inventive Principle:

Principle #3Local quality

3Device complexity

If a single-layer polishing pad is used, then device complexity is reduced, but the ability to decouple polishing surface and bulk properties is limited

Engineering Contradiction:

Improvepad structureVSAvoidproperty decoupling

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The polishing pad is segmented into two distinct layers with different hardness properties, enabling independent optimization of surface and bulk characteristics. This segmentation provides property decoupling while maintaining relatively simple manufacturing processes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The polishing pad uses composite material construction with a foundation layer of one hardness (8-15 Shore D) and a surface layer of softer material (3-7 Shore D). This composite approach enables property decoupling, allowing the bulk to provide structural support while the surface provides optimized polishing characteristics.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentEP2785496B1Polishing pad with foundation layer and polishing surface layer

Publication Date: 2021.11.24 CMC MATERIALS INC

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AI summary

Polishing pads with foundation layers and polishing surface layers are described. In an example, a polishing pad for polishing a substrate includes a foundation layer. A polishing surface layer is bonded to the foundation layer. Methods of fabricating polishing pads with a polishing surface layer bonded to a foundation layer are also described.