Polyurethane CMP Pads with Temperature-Dependent Modulus
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional chemical-mechanical polishing pads either exhibit high removal rates and planarization efficiency but with increased defectivity, or longer pad life but with reduced removal rates, failing to balance these performance metrics effectively.
Innovation Solution
Development of chemical-mechanical polishing pads with a polyurethane material having a high storage modulus at low temperatures and a low storage modulus at high temperatures, allowing for high planarization efficiency, reduced defectivity, and extended pad life through mild conditioning routines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If harder polishing pad materials are used, then removal rates and planarization efficiency are improved, but defectivity increases
Solution Approach 1:
The patent changes the physical and chemical parameters of the polyurethane material, specifically controlling the NCO index (isocyanate content) to range from 80 to 150 and using specific polyol molecular weights (1000-5000 g/mol), to achieve an optimal balance between hardness for removal rate and softness to reduce defects
Solution Approach 2:
The patent creates a composite polyurethane system combining specific polyols (polyester or polyether) with polyisocyanates at controlled ratios, forming a material that integrates the hardness needed for efficient polishing with the elasticity required to minimize wafer defects
2Object-affected harmful factors
If softer polishing pad materials are used, then defectivity is reduced, but removal rates and planarization efficiency decrease
Solution Approach 1:
The patent optimizes the NCO index parameter within the range of 80-150 and controls polyol molecular weight between 1000-5000 g/mol, achieving a material that is soft enough to reduce defects but maintains sufficient structural integrity for effective material removal
Solution Approach 2:
The composite polyurethane formulation combines flexible polyol chains with rigid polyisocyanate segments, creating a material that exhibits both the compliance needed to minimize defects and the mechanical strength required for productive polishing
3Productivity
If polyurethane with high storage modulus at low temperature is used, then planarization efficiency is improved, but pad life decreases due to reduced flexibility at operating temperatures
Solution Approach 1:
The patent introduces temperature-dependent modulus control by selecting polyols with specific molecular weights (1000-5000 g/mol) and controlling NCO index (80-150), creating a material that provides high modulus at room temperature for planarization efficiency while maintaining lower modulus at elevated operating temperatures for extended pad life
Solution Approach 2:
The patent creates a dynamic polyurethane material whose mechanical properties change with temperature, providing high stiffness at ambient conditions for effective planarization while becoming more compliant at operating temperatures to reduce wear and extend service life
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 pads achieve stable CMP removal rates, improved planarization efficiency, and reduced defectivity, along with increased pad life, making them suitable for advanced semiconductor wafer processing.
Implementation Method 1
a polyurethane material having a high storage modulus at low temperatures and a low storage modulus at high temperatures
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A chemical-mechanical polishing pad comprising a polyurethane polishing layer having a high storage modulus at low temperatures and a low storage modulus at high temperatures is disclosed. For example, the disclosed pad embodiments may be fabricated from a thermoplastic polyurethane having a ratio of storage modulus at 25 degrees C to storage modulus at 80 degrees C of 50 or more. The thermoplastic polyurethane polishing layer may further optionally have a Shore D hardness of 70 or more, a tensile elongation of 320 percent or less, a storage modulus at 25 degrees C of 1200 MPa or more, and/or a storage modulus at 80 degrees C of 15 MPa or less.