Porous Polyurethane CMP Pad With Controlled Pore Distribution
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Solution Overview
Problem
Current porous polyurethane polishing pads for CMP processes face challenges in controlling pore size and distribution, which affects breakdown voltage and polishing rate, with limited freedom in designing pore conformation and distribution.
Innovation Solution
A porous polyurethane polishing pad with a specific composition and process, featuring a urethane-based resin, curing agent, and controlled pore formation using a mixture of solid phase foaming agents and inert gases, resulting in a pad with an area-weighted average pore diameter of 10 μm to 40 μm, specific gravity of 0.7 g/cm3 to 0.9 g/cm3, and enhanced physical properties like breakdown voltage and polishing rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermally expanded microcapsules are used as foaming agent, then pore diameter can be uniformly controlled, but pore formation becomes difficult under high temperature reaction conditions (100°C or higher)
Solution Approach 1:
The patent changes the key parameter from microcapsule size to microcapsule wall thickness to achieve temperature resistance. By making the wall thickness 1/10 to 1/20 of the particle diameter (thicker walls), the microcapsules can withstand high temperature reaction conditions (100°C or higher) while maintaining uniform pore formation and diameter control.
2Object-generated harmful factors
If inert gas or volatile liquid phase foaming agent is used, then material discharge affecting CMP process is avoided, but precise control of pore size and density becomes difficult
Solution Approach 1:
The patent changes the control approach from dealing with gas phase (which is difficult to control) to using solid phase microcapsules with controlled wall thickness. This allows precise control of pore size (50 μm or less) and density while avoiding material discharge that affects CMP processes.
Solution Approach 2:
The patent uses composite microcapsules with specific wall thickness-to-diameter ratios, combining the advantages of solid phase foaming agents (controllability) while avoiding the harmful effects of material discharge associated with conventional foaming agents.
3Manufacturing precision
If single foaming agent is used, then pores can be formed with designed size and distribution, but design freedom and pore distribution control are limited
Solution Approach 1:
The patent introduces a new controllable parameter (wall thickness ratio of 1/10 to 1/20 of particle diameter) that enables diverse pore structures while maintaining uniform distribution. This parameter change provides design freedom for different pore sizes and densities without sacrificing control precision.
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 solution allows for uniform distribution of large and small pores, enhancing the pad's physical properties, preventing scratches, and improving polishing performance by maintaining consistent pore distribution and size, thus achieving improved breakdown voltage and polishing rate.
Implementation Method 1
microcapsules (i.e., thermally expanded microcapsules), whose size has been adjusted by a thermal expansion
Implementation Method 2
by generating a gas by a chemical reaction
Data Source
AI summary
Embodiments relate to a porous polyurethane polishing pad for use in a chemical mechanical planarization (CMP) process of semiconductors and a process for preparing the same. According to the embodiments, the size and distribution of the plurality of pores contained in the porous polyurethane polishing pad can be adjusted. Thus, it is possible to provide a porous polyurethane polishing pad that has enhanced physical properties such as a proper level of withstand voltage, excellent polishing performance (i.e., polishing rate), and the like.