CMP Polishing Pad Grooved Foundation Layer

Solution Overview

Problem

Conventional CMP polishing pads face a trade-off between across-wafer uniformity and within-die uniformity, with hard pads offering good die-level planarization but poor wafer-level uniformity, and soft pads providing good wafer-level 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 stable, non-compressible foundation layer and a softer polishing surface layer, where the foundation layer provides support and the surface layer reduces scratching, allowing for decoupling of material 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, or vice versa, and bonding them directly or through intervening layers to enhance peel resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

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

Engineering Contradiction:

Improvedie-level planarizationVSAvoidwafer-level uniformity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The polishing pad is segmented into multiple layers with different hardness properties: a harder top layer for die-level planarization and a softer bottom layer for wafer-level uniformity. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between local precision and global uniformity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the polishing pad have different mechanical properties - the top surface layer is harder to provide aggressive planarization where needed, while the bottom layer is softer to maintain overall wafer uniformity. This local differentiation of material properties enables simultaneous optimization of both contradictory requirements.

Inventive Principle:

Principle #3Local quality

2Reliability

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

Engineering Contradiction:

Improvewafer-level uniformityVSAvoiddie-level planarization

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The polishing pad is segmented into multiple layers with different hardness properties: a harder top layer for die-level planarization and a softer bottom layer for wafer-level uniformity. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between local precision and global uniformity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the polishing pad have different mechanical properties - the top surface layer is harder to provide aggressive planarization where needed, while the bottom layer is softer to maintain overall wafer uniformity. This local differentiation of material properties enables simultaneous optimization of both contradictory requirements.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

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

Engineering Contradiction:

Improvepad fabrication simplicityVSAvoiddecoupling of surface and bulk properties

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The polishing pad is segmented into multiple layers with different hardness properties: a harder top layer for die-level planarization and a softer bottom layer for wafer-level uniformity. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between local precision and global uniformity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The polishing pad uses composite material construction with multiple layers of different polymers (e.g., polyurethane top layer and polyethylene bottom layer) bonded together. This composite structure enables independent optimization of surface and bulk properties while maintaining manufacturing feasibility through established lamination techniques.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS9931729B2Polishing pad with grooved foundation layer and polishing surface layer

Publication Date: 2018.04.03 CMC MATERIALS INC

AI summary

Polishing pads with grooved foundation layers and polishing surface layers are described. In an example, a polishing pad for polishing a substrate includes a foundation layer having a pattern of grooves disposed therein. A continuous polishing surface layer is attached to the pattern of grooves of the foundation layer. In another example, a polishing pad for polishing a substrate includes a foundation layer with a surface having a pattern of protrusions disposed thereon. Each protrusion has a top surface and sidewalls. A non-continuous polishing surface layer is attached to the foundation layer and includes discrete portions. Each discrete portion is attached to the top surface of a corresponding one of the protrusions of the foundation layer. Methods of fabricating polishing pads with a polishing surface layer bonded to a grooved foundation layer are also described.