3D Network Polishing Pad for CMP Defect Reduction
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Solution Overview
Problem
Conventional chemical mechanical polishing (CMP) pads have suboptimal contact mechanics and fluid mechanics, leading to high defect formation and non-uniform polishing due to small real contact area and irregular surface texture, which requires frequent conditioning and compromises between planarization efficiency and defectivity.
Innovation Solution
A polishing pad with a three-dimensional network of interconnected unit cells, where polishing elements maintain a consistent cross-sectional area and height, allowing for dynamic contact and efficient fluid flow, reducing the need for conditioning and enhancing both planarization efficiency and defect reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP pads use irregular surface texture with small real contact area, then polishing rate may be maintained, but defect formation increases and polishing uniformity deteriorates
Solution Approach 1:
The polishing pad surface is segmented into discrete polishing elements arranged in a three-dimensional network, where each element acts as an independent contact point. This segmentation creates a controlled microstructure that increases real contact area while maintaining uniform pressure distribution, thereby reducing defects and improving polishing uniformity without sacrificing polishing rate.
Solution Approach 2:
The invention transitions from a conventional two-dimensional flat polishing surface to a three-dimensional network structure with height variations. This dimensional change allows the polishing elements to conform to substrate topography while maintaining consistent contact pressure, increasing real contact area and reducing defects caused by irregular surface texture.
2Manufacturing precision
If polishing pad surface is conditioned frequently to maintain consistent polishing surface, then polishing uniformity is maintained, but productivity decreases due to process interruptions
Solution Approach 1:
The three-dimensional network structure with uniform polishing elements is designed to self-maintain its polishing surface characteristics throughout its service life. The consistent cross-sectional area and height of polishing elements ensure uniform wear patterns that preserve the microstructure, eliminating the need for frequent conditioning interventions and maintaining high productivity.
Solution Approach 2:
The invention changes the structural parameters of the polishing pad from irregular conventional surfaces to a controlled three-dimensional network with specific height and cross-sectional area parameters. This parameter optimization ensures consistent polishing performance over extended periods, reducing the frequency of conditioning operations required to maintain polishing uniformity.
3Quantity of substance
If polishing pad uses high void fraction for slurry flow, then fluid mechanics improve, but mechanical strength and planarization efficiency decrease
Solution Approach 1:
The polishing pad employs local quality differentiation where polishing elements provide structural integrity and load-bearing capacity, while the spaces between elements facilitate slurry flow. This localized functional assignment allows high void fraction for improved fluid mechanics without compromising the mechanical strength needed for effective planarization.
Solution Approach 2:
The three-dimensional network structure functions as a composite system where the polishing element material provides mechanical strength and the void spaces enable fluid flow. This composite architecture reconciles the conflicting requirements of high slurry flow rate and sufficient structural integrity for planarization efficiency.
4Adaptability or versatility
If polishing elements have varying cross-sectional area, then conformity to substrate is improved, but polishing uniformity across the surface deteriorates
Solution Approach 1:
The polishing pad is divided into multiple discrete polishing elements with uniform cross-sectional areas, where the collective array provides surface conformity through their arrangement and height rather than individual element deformation. This segmentation maintains polishing uniformity while achieving substrate conformity through the network structure.
Solution Approach 2:
Surface conformity is achieved in the vertical dimension through the height of polishing elements rather than through variations in cross-sectional area. This dimensional approach allows uniform cross-sectional areas to maintain polishing uniformity while the overall network structure conforms to substrate topography.
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 provides a self-renewing polishing surface with increased real contact area and improved slurry flow, reducing defect formation and extending pad life while maintaining consistent polishing performance across multiple operations.
Implementation Method 1
a three-dimensional network of interconnected unit cells, the interconnected unit cells being reticulated for allowing fluid flow and removal of polishing debris
Implementation Method 2
The carrier assembly provides a controllable pressure between the wafer and polishing pad
Implementation Method 3
The wafer surface is polished and made planar by chemical and mechanical action of the polishing layer and polishing medium on the surface
Implementation Method 4
The wafer surface is polished and made planar by chemical and mechanical action of the polishing layer and polishing medium on the surface
Implementation Method 5
The origin of glazing is plastic flow of the polymeric material due to frictional heating and shear at the points of contact between the pad and the workpiece
Implementation Method 6
The origin of glazing is plastic flow of the polymeric material due to frictional heating and shear at the points of contact between the pad and the workpiece
Data Source
AI summary
The polishing pad (104) is useful for polishing at least one of magnetic, optical and semiconductor substrates (112) in the presence of a polishing medium (120). The polishing pad (104) includes a three-dimensional network of interconnected unit cells (225). The interconnected unit cells (225) are reticulated for allowing fluid flow and removal of polishing debris. A plurality of polishing elements (208, 308 and 408) form the three-dimensional network of interconnected unit cells (225). The polishing elements (208, 308 and 408) have a first end connected to a first adjacent polishing element at a first junction (209, 309 and 409) and a second end connected to a second adjacent polishing element at a second junction (209, 309 and 409) and having a cross-sectional area (222, 322 and 422) that remains within 30% between the first and the second junctions (209, 309 and 409). The polishing surface (200, 300 and 400) formed from the plurality of polishing elements (208, 308 and 408) remains consistent for multiple polishing operations.