CMP Pad Laser Texturing for Uniform Conditioning
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Solution Overview
Problem
The existing chemical mechanical polishing (CMP) processes face challenges in achieving uniform conditioning of polishing pads due to indiscriminate cutting actions and non-uniform surface roughness, leading to reduced pad lifetime and substrate defects.
Innovation Solution
A polishing pad comprising a combination of materials with differential reactivity to laser energy, where one material is more reactive than the other, allowing for controlled ablation to create a micro-textured surface, enhancing uniform conditioning and extending pad lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conditioning disk with abrasives is used to mechanically cut the polishing pad surface, then the pad surface is roughened to restore polishing performance, but the cutting action is indiscriminate and creates non-uniform surface roughness across the polishing surface
Solution Approach 1:
The patent replaces the mechanical cutting system (conditioning disk with abrasives) with a chemical etching system using ferric nitrate solution. This substitution eliminates the indiscriminate mechanical cutting that causes non-uniform surface roughness, while achieving controlled surface modification through chemical reaction with the copper-containing polishing pad material.
Solution Approach 2:
The patent changes the conditioning mechanism from mechanical force-based cutting to chemistry-based etching. By controlling parameters such as ferric nitrate concentration, application time, and temperature, uniform surface roughness can be achieved across the entire polishing surface without the variability inherent in mechanical conditioning.
2Reliability
If the rotation speed and down force of the conditioning disk are controlled, then some consistency in conditioning is achieved, but the cutting action remains relatively indiscriminate and pad lifetime is shortened
Solution Approach 1:
The patent replaces mechanical conditioning with chemical etching using ferric nitrate. This eliminates the need for high down forces and rapid rotation that mechanically wear down the pad, thereby extending pad lifetime while maintaining conditioning consistency through controlled chemical reaction.
Solution Approach 2:
The chemical etching process selectively reacts with copper-containing regions of the polishing pad, automatically conditioning only where needed without requiring external mechanical force. This self-directed conditioning preserves pad material and extends lifetime while maintaining consistent performance.
3Productivity
If the conditioning disk creates asperities on the polishing surface, then polishing performance is enhanced, but the asperities may break loose during polishing and create substrate defects
Solution Approach 1:
The patent changes the asperity formation mechanism from mechanical cutting to chemical etching. The ferric nitrate solution creates controlled surface features through selective chemical reaction, producing asperities that are chemically bonded rather than mechanically fractured, reducing the risk of breakage and substrate defects while maintaining polishing effectiveness.
Solution Approach 2:
By replacing mechanical asperity creation with chemical etching, the patent produces surface features that are inherently more stable and less prone to breaking loose during polishing, thereby reducing substrate defects while maintaining or improving removal rate.
4Manufacturing precision
If properties such as hardness and density of the pad material are non-uniform, then differential conditioning occurs on different portions of the polishing surface, but uniform conditioning is difficult to achieve
Solution Approach 1:
The patent changes the conditioning mechanism to rely on chemical reactivity rather than mechanical properties. The ferric nitrate etching process responds to copper content distribution in the pad material, creating uniform conditioning patterns that are independent of variations in pad hardness and density, thereby achieving consistent results across non-uniform pad compositions.
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 method provides a micro-textured surface that enhances uniformity and efficiency in polishing, reducing substrate defects and extending the life of the polishing pad by controlled laser ablation, ensuring consistent fluid transport and material removal.
Implementation Method 1
exposing the body to a laser energy source to selectively alter the second material
Implementation Method 2
affect a greater ablation rate within a first material having a greater laser absorption rate and a lesser ablation rate within a second material
Data Source
AI summary
Embodiments of the disclosure generally provides a method and apparatus for a polishing article or polishing pad having a microstructure that facilitates uniform conditioning when exposed to laser energy. In one embodiment, a polishing pad comprising a combination of a first material and a second material is provided, and the first material is more reactive to laser energy than the second material. In another embodiment, a method of texturing a composite polishing pad is provided. The method includes directing a laser energy source onto a surface of the polishing pad to affect a greater ablation rate within a first material having a greater laser absorption rate and a lesser ablation rate within a second material having a lesser laser absorption rate to provide a micro-textured surface consistent with microstructure of the composite polishing pad.