CMP Pad with Closed Cell Pores for High Removal Rate
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Solution Overview
Problem
Current polishing pads for semiconductor and magnetic substrates face challenges in achieving high removal rates and low defectivity, particularly with the increasing complexity and smaller feature sizes of integrated circuits, where CMP-induced defects like scratching become more significant, and stringent planarity and topography requirements are harder to meet.
Innovation Solution
A polishing pad with a polymeric matrix and closed cell pores, having an ultimate tensile strength of at least 3,000 psi, featuring opened pores with an average diameter of 1 to 50 μm and an exponential decay constant of 1 to 10 μm, and a texture developed by periodic or continuous conditioning with an abrasive, ensuring compatibility between the conditioner's half height half width and the pad's decay constant for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polymeric polishing pads are used, then mechanical integrity and chemical resistance are provided, but removal rate is insufficient for demanding polishing applications
Solution Approach 1:
The patent employs a polymeric matrix with closed cell pores (1-50 μm diameter, 1-40 volume percent) that provides both mechanical integrity and enhanced removal rate. The porous structure enables effective material removal while maintaining pad stability through controlled porosity distribution characterized by exponential decay constant τ of 1-10 μm.
Solution Approach 2:
The patent optimizes multiple parameters including ultimate tensile strength (≥3000 psi), pore size distribution (exponential decay constant τ), pore volume percent (1-40%), and conditioner half-height half-width (W1/2 ≤ τ). These parameter changes enable the pad to achieve both high removal rate and stable polishing performance.
2Productivity
If aggressive diamond conditioning is implemented, then removal rate and stability are increased, but pad glazing and loss of polishing ability occur without conditioning
Solution Approach 1:
The pad's closed cell pore structure and optimized porosity distribution enable it to maintain polishing ability without excessive external conditioning. The internal pore structure self-regulates to prevent glazing while allowing controlled material removal, reducing dependence on aggressive conditioning procedures.
Solution Approach 2:
The controlled closed cell pore structure (1-50 μm, 1-40 volume percent) with exponential decay constant τ provides inherent resistance to glazing. The porous matrix allows slurry penetration and maintains polishing surfaces without requiring aggressive conditioning to prevent performance degradation.
3Manufacturing precision
If high performance polishing pads with specialized polymer matrices are used, then planarization and defectivity are improved, but removal rate is insufficient
Solution Approach 1:
The patent uses a polymeric matrix with optimized closed cell pores (1-50 μm, 1-40 volume percent) that simultaneously achieves low defectivity planarization and high removal rate. The controlled porosity with exponential decay constant τ=1-10 μm provides both smooth surface finish and effective material removal capability.
Solution Approach 2:
The patent employs a composite structure combining polymeric matrix with closed cell pores and opened pores on the surface. This composite architecture integrates the benefits of both structures: internal pore closure for defect-free polishing and surface opening for effective material removal, achieving both high planarization quality and removal rate.
4Device complexity
If smaller feature sizes are polished, then device complexity is reduced, but CMP-induced defectivity such as scratching increases
Solution Approach 1:
The controlled closed cell pore structure (1-50 μm) with exponential decay constant τ provides a polishing surface that minimizes scratching and defectivity during CMP of small features. The uniform porosity distribution ensures consistent material removal without inducing scratches that would compromise small feature integrity.
Solution Approach 2:
The patent optimizes parameters including ultimate tensile strength (≥3000 psi), pore size (1-50 μm), pore volume (1-40%), and decay constant (τ=1-10 μm) to achieve low defectivity polishing. These parameter changes enable safe polishing of small features without excessive scratching or damage.
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 enhances the removal rate and maintains steady polishing performance while reducing defects, particularly suitable for demanding applications like STI, HDP/SiN, TEOS/SiN, or SACVD/SiN, by creating channels that contribute to polishing and preventing decay in removal rate.
Implementation Method 1
the polymeric matrix having closed cell pores, the closed cell pores having an average diameter of 1 to 50 μm, being 1 to 40 volume percent of the polishing pad
Implementation Method 2
having a texture developed by implementing periodic or continuous conditioning with an abrasive having a characteristic half height half width, W1/2, less than or equal to the value of τ
Data Source
AI summary
The polishing pad is suitable for planarizing at least one of semiconductor, optical and magnetic substrates. The polishing pad has an ultimate tensile strength of at least 3,000 psi (20.7 MPa) and polymeric matrix containing closed cell pores. The closed cell pores have an average diameter of 1 to 50 μm and represent 1 to 40 volume percent of the polishing pad. The pad texture has an exponential decay constant, τ, of 1 to 10 μm as a result of the natural porosity of the polymeric matrix and a surface texture developed by implementing periodic or continuous conditioning with an abrasive. The surface texture has a characteristic half height half width, W1/2 that is less than or equal to the value of τ.