Polyurethane CMP Pad Composition for Stable Conditioning Microtexture
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional chemical mechanical polishing pads made from soft polyurethane materials face challenges in maintaining a favorable microtexture during conditioning due to high ductility, leading to poor groove quality and increased polishing defects, which can compromise semiconductor device functionality.
Innovation Solution
A chemical mechanical polishing pad with a polishing layer composed of a reaction product of an isocyanate terminated urethane prepolymer and a curative system, including a high molecular weight polyol curative and difunctional curative, providing a balance of properties such as Shore D hardness, elongation to break, and tensile modulus, enabling effective diamond conditioning and groove formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If soft polyurethane materials are used for polishing pads, then polishing rate is improved, but groove quality deteriorates due to high ductility
Solution Approach 1:
The patent modifies the polyurethane material parameters by controlling the NCO index (isocyanate to hydroxyl ratio) to be 0.8-1.2 and adjusting Shore D hardness to 40-60. This parameter optimization enables the material to achieve both high elongation (100-300%) for good groove formation and sufficient hardness for maintaining groove quality during polishing operations.
Solution Approach 2:
The patent creates a composite polyurethane system by reacting isocyanate-terminated urethane prepolymer with a curative system containing polyol and difunctional curative. This composite approach combines the benefits of softness and ductility from polyol with the structural integrity from difunctional curative, achieving both high polishing rate and good groove quality.
2Reliability
If softer polishing pad material is used, then polishing defects are reduced, but conditioning performance deteriorates
Solution Approach 1:
The patent optimizes the Shore D hardness parameter to a specific range of 40-60, which is softer than conventional pads to reduce polishing defects like micro-scratches and chatter marks. Simultaneously, the NCO index is controlled at 0.8-1.2 to ensure the material has appropriate ductility for effective diamond conditioning, creating favorable microtexture without excessive softness that would hinder conditioning.
Solution Approach 2:
The patent introduces dynamic properties to the polishing pad material by achieving high elongation (100-300%) through controlled polyurethane formulation. This dynamic characteristic allows the material to deform and recover during conditioning, enabling diamond particles to effectively create microtexture while maintaining structural integrity during polishing.
3Productivity
If high ductility material is used, then polishing rate is improved, but microtexture maintenance deteriorates during conditioning
Solution Approach 1:
The patent carefully balances the Shore D hardness parameter at 40-60 and elongation at 100-300% through controlled polyurethane synthesis. This parameter optimization ensures the material has sufficient ductility to maintain high polishing rates while having enough structural stability to preserve favorable microtexture during repeated conditioning operations.
Solution Approach 2:
The patent performs preliminary optimization of the polyurethane formulation before the polishing process begins. By controlling the NCO index and curative system composition during manufacturing, the material is pre-configured with the optimal balance of ductility and stability, enabling it to maintain microtexture throughout the conditioning and polishing cycles without requiring frequent reconditioning.
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 achieves efficient polishing with reduced defects by creating a desirable microtexture, maintaining high polishing rates while minimizing surface damage, thus ensuring the integrity of semiconductor devices.
Implementation Method 1
a polishing layer composed of a reaction product of an isocyanate terminated urethane prepolymer and a curative system, including a high molecular weight polyol curative and difunctional curative
Implementation Method 2
Pad surface 'conditioning' or 'dressing' is critical to maintain a consistent polishing surface for stable polishing performance. Over time the polishing surface of the polishing pad wears down, smoothing over the microtexture of the polishing surface—a phenomenon called 'glazing'.
Implementation Method 3
The conditioning process as described cuts microscopic furrows into the pad surface, both abrading and plowing the pad material and renewing the polishing texture.
Implementation Method 4
a Shore D hardness of 40 to 60; an elongation to break of 125 to 300%; a tensile modulus of 100 to 300 (MPa)
Data Source
AI summary
A chemical mechanical polishing pad is provided containing a polishing layer having a polishing surface, wherein the polishing layer comprises a reaction product of ingredients, including: an isocyanate terminated urethane prepolymer; and, a curative system, containing a high molecular weight polyol curative; and, a difunctional curative.