Polishing Pad Thermal Expansion Reduction via Inorganic Nanoparticles
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Solution Overview
Problem
Conventional polishing pads experience significant thermal expansion during the chemical mechanical polishing process, leading to deformation and a negative impact on the polishing effect due to their high thermal expansion coefficients.
Innovation Solution
A polishing pad is prepared with a reduced thermal expansion coefficient by filling grooves with inorganic nanoparticles and a cured liquid polymer, using a mold made of low-melting inorganic materials like ice, and optimizing the distribution of nanoparticles to minimize thermal expansion and enhance polishing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional polishing pad is used during high-speed polishing, then polishing process can be carried out, but thermal expansion causes deformation and reduces polishing precision
Solution Approach 1:
The polishing pad is constructed as a composite material system consisting of a polymer base material combined with inorganic filler particles (such as氧化铝 or silicon dioxide). This composite structure leverages the low thermal expansion coefficient of inorganic materials to counterbalance the high thermal expansion of the polymer matrix, achieving overall thermal stability while maintaining the cushioning and flexibility properties of the polymer base.
Solution Approach 2:
The patent modifies the thermal expansion parameter of the polishing pad by controlling the composition ratio, particle size distribution, and spatial arrangement of inorganic fillers within the polymer matrix. By adjusting these parameters, the overall thermal expansion coefficient of the composite pad is reduced to match or approach that of silicon wafers, minimizing differential thermal expansion during polishing operations.
2Productivity
If polishing is performed at high speed to improve productivity, then polishing efficiency increases, but heat generation causes thermal expansion and deformation
Solution Approach 1:
The patent changes the thermal parameters of the polishing pad by incorporating inorganic fillers with low thermal expansion coefficients and high thermal stability. This modification allows the pad to withstand higher operating temperatures without excessive expansion, enabling sustained high-speed polishing operations.
Solution Approach 2:
The patent converts the harmful effect of heat generation during high-speed polishing into a beneficial outcome. By using inorganic fillers that are thermally stable, the heat generated during polishing is better managed, and the thermal energy is partially used to activate beneficial thermal effects such as enhanced chemical reactions in chemical-mechanical polishing while preventing detrimental thermal expansion.
3Stability of the object's composition
If inorganic nanoparticles are added to reduce thermal expansion, then thermal stability improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by distributing inorganic filler particles non-uniformly within the polishing pad structure. Different regions of the pad contain different concentrations or types of fillers optimized for their specific functional requirements. For example, the contact surface may have a higher concentration of low-expansion particles for thermal stability, while internal regions may have different compositions for structural support.
Solution Approach 2:
The patent utilizes a porous structure in the polishing pad that incorporates inorganic fillers within the pore spaces or as reinforcement elements. This porous architecture provides multiple benefits: it reduces the overall density and thermal mass of the pad, facilitates heat dissipation through increased surface area, and allows the inorganic fillers to be distributed in a way that minimizes their impact on manufacturing complexity while maximizing thermal stability.
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 exhibits reduced deformation and improved polishing efficiency due to its lower thermal expansion coefficient, maintaining stability and effectiveness during high-speed polishing processes.
Implementation Method 1
the thermal expansion coefficient of the inorganic nanoparticles is lower than that of the cured liquid polymer, the thermal expansion coefficient of the overall polishing pad can be effectively reduced
Implementation Method 2
placing the polishing pad transition structure in an environment at a temperature higher than or equal to a first temperature threshold, and the cured liquid polymer and the polishing pad transition structuring constituting the polishing pad
Implementation Method 3
pouring a mixture of a liquid polymer and a curing agent on the polishing pad transition structure, and evacuating air in the liquid polymer and the plurality of grooves
Implementation Method 4
raising the ambient temperature to be higher than the second temperature threshold, so that the mold melts, and the solidified liquid polymer forms the polishing pad transition structure
Data Source
AI summary
A method for preparing a polishing pad includes: preparing a polishing pad transition structure formed with a plurality of grooves, openings of the plurality of grooves being all located on a same side surface of the polishing pad transition structure; filling the plurality of grooves of the polishing pad transition structure with inorganic nanoparticles; pouring a mixture of a liquid polymer and a curing agent on the polishing pad transition structure, and evacuating air in the liquid polymer and the plurality of grooves; and placing the polishing pad transition structure in an environment at a temperature higher than or equal to a first temperature threshold, and the cured liquid polymer and the polishing pad transition structure constituting the polishing pad.