Polishing Pad Liquid-Filled Capsule Uniformity
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Solution Overview
Problem
Polishing pads used in chemical-mechanical planarization processes suffer from non-uniformity due to uneven expansion of polymeric capsules during the curing process, leading to inconsistent pad porosity and density, which affects the CMP process.
Innovation Solution
The use of polymeric capsules with a liquid core and a thin, non-porous polymeric shell that matches the density of the polymeric matrix material, preventing contact during formation and allowing for controlled rupture to create surface asperities, reduces thermal expansion and ensures uniform distribution and porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymeric capsules are used to create surface asperities, then polishing performance is improved, but non-uniform expansion during curing causes non-uniform porosity and density
Solution Approach 1:
The patent changes the physical state of the capsule core from gas to liquid, which fundamentally alters the thermal expansion behavior during curing. Liquid-filled capsules expand significantly less than gas-filled capsules because liquids are nearly incompressible and have much lower thermal expansion coefficients. This parameter change directly addresses the non-uniform expansion problem while maintaining the capsule's ability to create surface asperities when ruptured.
Solution Approach 2:
The patent uses composite capsule structures with liquid cores suspended in polymeric matrix material. The liquid core provides thermal stability and minimal expansion, while the polymeric shell provides structural integrity and controlled rupture characteristics. This composite approach combines the benefits of capsule-based asperity formation with the stability of liquid-filled structures, resolving the contradiction between polishing performance and manufacturing uniformity.
2Reliability
If capsules are embedded in polishing pad, then surface asperities are created, but capsules may float or sink during mixing causing non-uniform distribution
Solution Approach 1:
The patent changes the density parameter of the capsule by filling it with liquid instead of leaving it hollow or gas-filled. The liquid-filled capsule's density can be tuned to match the polymeric matrix material, eliminating buoyancy forces that cause floating or sinking during mixing. This density matching ensures uniform distribution throughout the pad while maintaining the capsule's function of creating surface asperities upon rupture.
3Ease of manufacture
If traditional casting method is used, then manufacturing is simple, but pad-to-pad uniformity is poor
Solution Approach 1:
The patent changes the thermal properties of the capsule system by using liquid-filled capsules that conduct heat more effectively and expand less during curing. This reduces differential heating and thermal runaway effects that cause pad-to-pad variability. The liquid core acts as a heat sink and thermal conductor, promoting more uniform curing across multiple pads manufactured in sequence, thereby improving consistency without complicating the casting process.
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
This approach results in a polishing pad with improved uniformity, reduced thermal expansion, and enhanced thermal conductivity, leading to more consistent polishing performance and reduced waste, while also enabling the production of optically transparent pads suitable for endpoint detection.
Implementation Method 1
polymeric capsules with a liquid core and a thin, non-porous polymeric shell that matches the density of the polymeric matrix material, preventing contact during formation and allowing for controlled rupture to create surface asperities, reduces thermal expansion and ensures uniform distribution and porosity
Implementation Method 2
the polishing composition on the surface of the polishing pad is contacted with the surface of the substrate (the working environment), causing the desired chemical reaction, and mechanical polishing takes place
Implementation Method 3
causing the desired chemical reaction, and mechanical polishing takes place
Implementation Method 4
the polymeric shell having a polishing surface that ruptures to create surface asperities for polishing the substrates
Implementation Method 5
Polishing pad surface asperities aid in transporting the polishing composition during the CMP process
Data Source
AI summary
The present invention relates to a method of manufacturing a polishing pad with embedded polymeric capsules useful for planarizing a substrate in a CMP process using a polishing composition. The method reduces non-uniformity of the polishing pad due to capsule floating, differential heating and capsule expansion by the use of novel capsule materials. The method also increases the efficiency of the manufacturing process by reducing the number of defective products and reducing waste.