Phase-Separated Polishing Pad for CMP Uniformity
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Solution Overview
Problem
Current chemical mechanical planarization (CMP) polishing pads face challenges in achieving uniformity and preventing dishing and edge erosion, especially with larger wafer diameters, and require frequent conditioning, which increases costs and reduces process efficiency.
Innovation Solution
A textured polishing pad with a combination of a first continuous polymer phase and a second discontinuous polymer phase, featuring grooves and porous elements, is developed. The pad includes polishing elements bonded to a support layer, allowing for improved retention of working liquids and reduced lateral movement, which enhances polishing uniformity and extends pad life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional polishing pads are used for CMP processes with larger wafer diameters, then polishing can be performed, but polishing uniformity deteriorates and dishing/edge erosion occurs
Solution Approach 1:
The polishing pad is divided into multiple discrete polishing elements (protrusions) that are laterally connected but independently movable. This segmentation allows each element to independently conform to the wafer surface, improving polishing uniformity across large wafer diameters while preventing dishing and edge erosion through distributed contact points
Solution Approach 2:
The polishing elements are designed to be moveable in the axis normal to the polishing surface while being laterally constrained. This dynamic structure allows the elements to adapt their height and position during polishing, maintaining optimal contact with the wafer surface and improving polishing uniformity without causing dishing or edge erosion
2Productivity
If conventional polishing pads are used, then polishing can proceed, but frequent conditioning is required which reduces productivity
Solution Approach 1:
The segmented structure with laterally connected but independently movable polishing elements distributes wear across multiple elements. This extends pad life by preventing localized wear degradation, reducing the frequency of conditioning operations, and improving overall productivity
Solution Approach 2:
The phase-separated polymer blend structure with specific mechanical properties and the textured surface geometry change the wear characteristics of the pad. These parameter changes result in more uniform wear distribution and extended operational life, reducing conditioning frequency and improving productivity
3Manufacturing precision
If a multiplicity of polishing elements are used to improve uniformity, then lateral movement restriction is needed, but this increases device complexity
Solution Approach 1:
The polishing pad utilizes a phase-separated polymer blend that inherently provides the mechanical properties needed to constrain lateral movement of polishing elements. This composite material approach achieves lateral restriction without additional complex structural components, maintaining polishing uniformity while avoiding increased device complexity
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 improves within-wafer polishing uniformity, increases edge die yield, and reduces the need for frequent pad conditioning, enabling more efficient processing of larger wafers with maintained surface quality and extended pad durability.
Implementation Method 1
a first continuous polymer phase and a second discontinuous polymer phase
Implementation Method 2
improved retention of working liquids
Data Source
AI summary
Polishing pads containing a phase-separated polymer blend, and methods of making and using such pads in a polishing process. In one exemplary embodiment, the polishing pads include a multiplicity of polishing elements integrally formed in a sheet. In another exemplary embodiment, the polishing elements are bonded to a support layer, for example by thermal bonding. In certain embodiments, the polishing pad may additionally include a compliant layer affixed to the support layer, and optionally, a polishing composition distribution layer.