Hydroxyapatite CMP Composition for Acid-Cleanable Abrasive Removal
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Solution Overview
Problem
Conventional CMP methods struggle to effectively remove abrasive grains, particularly those with small sizes, leading to defects in semiconductor substrates due to incomplete cleaning, which is exacerbated by the miniaturization demands in the semiconductor industry.
Innovation Solution
Employing hydroxyapatite (HAp) as an abrasive grain in the CMP process, followed by cleaning with an acidic aqueous solution, such as citric acid, to dissolve and remove residual HAp, ensuring thorough abrasive grain removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP methods are used with traditional abrasive grains, then polishing can be performed, but small abrasive grains cannot be effectively removed leading to substrate defects
Solution Approach 1:
The patent changes the chemical composition parameter of the abrasive grain from conventional materials (silica, ceria) to hydroxyapatite, which has different chemical reactivity characteristics. This parameter change enables the abrasive grain to be selectively removed by acid cleaning while maintaining polishing effectiveness, thereby resolving the contradiction between achieving good polishing results and ensuring complete abrasive removal.
2Manufacturing precision
If the size of abrasive grain is reduced to meet miniaturization demands, then polishing precision improves, but cleaning performance deteriorates making removal more difficult
Solution Approach 1:
The patent changes the chemical composition parameter of the abrasive grain to hydroxyapatite, which has specific acid solubility characteristics. This enables even sub-micron sized grains to be effectively dissolved and removed by acid cleaning solutions, resolving the contradiction between achieving fine polishing precision with small grains and maintaining ease of cleaning removal.
3Reliability
If acid cleaning is applied to remove abrasive grains, then abrasive removal improves, but substrate etching may occur causing new defects
Solution Approach 1:
The patent converts the potential harmful effect of acid on the substrate into a beneficial selective removal process. By choosing hydroxyapatite as the abrasive grain, the process exploits the fact that HAp is acid-soluble while typical substrate materials (silicon dioxide, silicon nitride, etc.) are acid-resistant. This allows the acid cleaning step to selectively remove abrasive grains without etching the substrate, transforming what could be a harmful universal etching effect into a beneficial selective cleaning 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
Facilitates the reliable removal of even small abrasive grains, reducing defects and enhancing polishing precision by minimizing residual particles on the substrate surface.
Implementation Method 1
bringing the substrate into contact with an acid to remove the residual HAp
Data Source
AI summary
A process of chemical mechanical polishing (CMP) is provided, the process including the step of subjecting a substrate to chemical mechanical polishing (CMP) using a chemical mechanical polishing composition including an abrasive grain that is hydroxyapatite (HAp), water, and a pH adjuster. Upon cleaning of substrate after CMP, residual HAp can be removed by bringing the substrate into contact with an acid.