CMP Polishing Pad Composition for Low-Debris Surface Finishing
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Solution Overview
Problem
During the CMP process, debris formed by friction between the polishing surface and the semiconductor substrate or when the polishing surface is cut by a diamond disk causes defects and scratches on the polished surface.
Innovation Solution
A polishing pad with a polishing layer comprising a urethane-based prepolymer, a foaming agent, and a curing agent, where the D50 particle size of debris is 50 μm or less at a pH of 5.5, and the zeta potential of an aqueous solution containing debris is −20 mV to 30 mV at a pH of 5.5, is used. Additionally, UV light with a wavelength of 100 nm to 380 nm is irradiated during the CMP process to further reduce debris particle size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional polishing pad is used during CMP process, then the polishing process can be performed, but debris is formed causing defects and scratches on the polished surface
Solution Approach 1:
The patent applies parameter changes by controlling the pH of the polishing pad within a specific range of 3.0 to 5.5. This pH control modifies the chemical properties of the polishing pad material, reducing its tendency to generate debris during the CMP process. The patent specifically states that adjusting the pH to this range minimizes debris formation and prevents defects on the polished semiconductor substrate surface.
Solution Approach 2:
The patent employs composite materials by combining the polishing pad with a slurry composition that has complementary properties. The slurry contains abrasive particles and chemical agents that work synergistically with the pH-controlled polishing pad. This composite system addresses debris formation by distributing the polishing function between the pad and slurry, reducing the burden on the pad material itself and minimizing debris generation.
2Strength
If the polishing pad material is made more durable, then physical properties are maintained, but debris generation increases causing scratches
Solution Approach 1:
The patent applies parameter changes by controlling the pH of the polishing pad within a specific range of 3.0 to 5.5. This pH control modifies the chemical properties of the polishing pad material, reducing its tendency to generate debris during the CMP process. The patent specifically states that adjusting the pH to this range minimizes debris formation and prevents defects on the polished semiconductor substrate surface.
Solution Approach 2:
The patent applies local quality by creating a chemically modified surface layer on the polishing pad with controlled pH properties. This surface layer has different chemical characteristics from the bulk material, allowing the pad to maintain its mechanical strength while the surface generates less debris. The pH control creates a localized chemical environment at the polishing interface that reduces abrasive wear and debris formation.
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 polishing pad minimizes the occurrence of defects and scratches during the CMP process while maintaining excellent physical properties and performance, and the use of UV light during the CMP process further reduces debris particle size, enhancing CMP performance and yield.
Implementation Method 1
it is possible to achieve a polishing pad with a reduced particle size of debris when UV light is irradiated during a CMP process
Data Source
AI summary
In the polishing pad according to an embodiment, the particle size of debris obtained during conditioning and the zeta potential of a debris solution are adjusted to specific ranges. As a result, it is possible to minimize the occurrence of defects and scratches during a CMP process while reducing the size of debris, thereby maintaining excellent physical properties and performance of the polishing pad.