Polishing Composition Selective Titanium Nitride Removal
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Solution Overview
Problem
The existing chemical mechanical polishing (CMP) techniques for semiconductor substrates have an insufficient ratio of polishing removal rate for titanium nitride film to silicon oxide film and poor dispersion stability, making it challenging to effectively polish titanium nitride films while minimizing the removal rate of silicon oxide films.
Innovation Solution
A polishing composition comprising abrasive grains with positive zeta potential, an inorganic acid, a surfactant with a polypropylene glycol structure, and hydrogen peroxide as an oxidizing agent, maintained at a pH between 2 and 4, which enhances the selective removal of titanium nitride over silicon oxide and improves dispersion stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a polishing composition containing abrasive material, hydrogen peroxide, complexing agent, and film forming agent is used to polish titanium nitride film, then the polishing removal rate for titanium nitride film is improved, but the polishing removal rate for silicon oxide film increases excessively, resulting in insufficient selection ratio
Solution Approach 1:
The patent changes the chemical parameters of the polishing composition by replacing organic complexing agents with inorganic acids (phosphoric acid, sulfuric acid, or boric acid) and adjusting the pH to a specific range (2-4), which fundamentally alters the chemical interaction with titanium nitride and silicon oxide, enabling selective polishing without excessive removal of silicon oxide
Solution Approach 2:
The patent introduces an intermediary substance (inorganic acid) that mediates the polishing process by selectively interacting with titanium nitride while being less aggressive toward silicon oxide, thus controlling the removal rates and improving the selection ratio
2Productivity
If conventional polishing composition is used to achieve high polishing removal rate for titanium nitride, then productivity is improved, but dispersion stability of the polishing composition deteriorates
Solution Approach 1:
The patent optimizes the pH parameter to a specific range (2-4) and uses inorganic acids instead of organic complexing agents, which fundamentally changes the chemical stability characteristics of the composition, preventing aggregation and maintaining dispersion stability while preserving high polishing performance
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 solution achieves a higher polishing removal rate for titanium nitride films while suppressing the removal rate of silicon oxide films, thereby increasing the selection ratio and maintaining long-term dispersion stability of the polishing composition.
Implementation Method 1
the oxidizing agent is hydrogen peroxide
Implementation Method 2
CMP is a method for flattening a surface of an object to be polished (polishing object) such as a semiconductor substrate using a polishing composition (slurry) containing abrasive grains such as silica, alumina, or ceria
Data Source
AI summary
To provide a polishing composition that can polish titanium nitride film at a higher polishing removal rate with respect to the polishing removal rate for silicon oxide film (specifically, a high selection ratio expressed removal rate titanium as polishing for nitride film/polishing removal rate for silicon oxide film) and that has high dispersion stability.A polishing composition containing abrasive grains, an acid, a surfactant, and an oxidizing agent, wherein the abrasive grains have a positive zeta potential, the acid is an inorganic acid, the surfactant contains a compound having a polypropylene glycol structure, the oxidizing agent is hydrogen peroxide, and the pH is 2 or more and 4 or less.