CMP Pad Stack with Curative Package for Groove Formation
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Solution Overview
Problem
Conventional chemical mechanical polishing pads face challenges in creating favorable microtexture during conditioning due to high ductility, leading to poor groove quality and increased risk of polishing defects, which can result in electrical breaks or shorts in semiconductor devices.
Innovation Solution
A chemical mechanical polishing pad stack comprising a polishing layer with a unique combination of properties, including a density greater than 0.6 g/cm3, Shore D hardness of 5 to 40, and elongation to break of 100 to 450%, achieved through a polyfunctional isocyanate and curative package with specific molecular weight and hydroxyl group ratios, bonded to a rigid layer with a hot melt adhesive, facilitating enhanced conditionability and machinability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polishing pads use high ductility materials to achieve softness, then polishing defects are reduced, but conditionability deteriorates due to poor groove quality
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molecular weight (2,500-100,000) and hydroxyl group count (3-10 per molecule) of the polyol curative, along with the stoichiometric ratio of curative to isocyanate (0.85-1.15). These parameter adjustments create a polishing layer with optimized elasticity and density (0.6-1.2 g/cm³) that enables both defect reduction and improved conditionability through proper groove formation during conditioning.
Solution Approach 2:
The patent uses composite materials by combining polyfunctional isocyanate with a specific polyol curative system (amine-initiated polyol plus high molecular weight polyol in 25-95 wt% ratio). This composite curative package creates a crosslinked polyurethane network with balanced mechanical properties, achieving Shore D hardness of 5-40 while maintaining elongation to break of 100-450%, thus resolving the contradiction between softness and conditionability.
2Strength
If polishing pad density is increased to improve structural integrity, then machinability deteriorates due to reduced conditionability
Solution Approach 1:
The patent applies parameter changes by controlling the density within the range of 0.6-1.2 g/cm³ through optimization of the polyol curative molecular weight and hydroxyl group content. This density optimization maintains sufficient structural integrity for handling and mounting while preserving adequate machinability for groove formation and microtexture creation during conditioning processes.
Solution Approach 2:
The patent applies local quality by creating different regional properties within the polishing layer: the bulk material provides structural integrity through crosslinked network formation, while the surface layer develops favorable microtexture and groove structures during conditioning. The specific curative composition enables this spatial differentiation of properties, with the surface responding appropriately to mechanical conditioning while the bulk maintains strength.
3Reliability
If polishing layer hardness is reduced to minimize polishing defects, then groove quality deteriorates due to excessive ductility
Solution Approach 1:
The patent applies parameter changes by optimizing the Shore D hardness to the range of 5-40 through controlled crosslinking density achieved by adjusting the curative package composition and stoichiometric ratio. This hardness optimization creates a balance where the material is soft enough to minimize polishing defects but sufficiently rigid to accept and maintain groove structures during conditioning, achieving cut rates of 25-150 μm/hr.
Solution Approach 2:
The patent uses composite materials by formulating a dual-curative system where amine-initiated polyol (at least 5 wt%) provides rapid crosslinking for structural development, while high molecular weight polyol (25-95 wt%) contributes to flexibility and groove acceptance. This composite curative approach creates a material with balanced hardness and ductility, achieving elongation to break of 100-450% while maintaining Shore D hardness of 5-40 for proper groove formation.
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 polishing pad stack provides improved conditionability and machinability, reducing polishing defects and maintaining planarity, thereby ensuring the electrical integrity of semiconductor devices by effectively creating microtexture and maintaining groove quality.
Implementation Method 1
the polishing layer comprises the reaction product of ingredients, including: a polyfunctional isocyanate; and, a curative package
Implementation Method 2
the polishing layer comprises the reaction product of ingredients, including: a polyfunctional isocyanate; and, a curative package
Implementation Method 3
a hot melt adhesive bonding the polishing layer to the rigid layer
Data Source
AI summary
A chemical mechanical polishing pad stack is provided containing: a polishing layer; a rigid layer; and, a hot melt adhesive bonding the polishing layer to the rigid layer; wherein the polishing layer comprises the reaction product of ingredients, including: a polyfunctional isocyanate; and, a curative package; wherein the curative package contains an amine initiated polyol curative and a high molecular weight polyol curative; wherein the polishing layer exhibits a density of greater than 0.6 g/cm3; a Shore D hardness of 5 to 40; an elongation to break of 100 to 450%; and, a cut rate of 25 to 150 μm/hr; and, wherein the polishing layer has a polishing surface adapted for polishing the substrate.