Polishing Composition for TiN/SiO2 Selectivity in CMP
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Solution Overview
Problem
Existing polishing compositions struggle to control the polishing selection ratio effectively when dealing with semiconductor substrates containing multiple film types, particularly in enhancing the removal rate of certain films like titanium nitride while suppressing the removal rate of others such as silicon oxide.
Innovation Solution
A polishing composition comprising abrasive grains with positive zeta potential, an organic acid as a pH adjuster, a nonionic surfactant as a polishing inhibitor, and hydrogen peroxide as an oxidizing agent, maintained at a pH of 2 to 4, to enhance the polishing removal rate of titanium nitride and suppress the removal rate of silicon oxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional polishing compositions are used, then general polishing can be performed, but the polishing selection ratio between different film types cannot be controlled
Solution Approach 1:
The invention changes the chemical parameters of the polishing composition by introducing an organic acid (formic acid, acetic acid, propionic acid, butyric acid, or valeric acid) and controlling the pH to 3 or lower. This parameter change enables selective polishing by altering the chemical reactivity between the polishing composition and different film types, achieving a polishing selection ratio of TiN/SiO2 of 10 or more
Solution Approach 2:
The organic acid acts as an intermediary substance that mediates the interaction between the polishing composition and the film surfaces. It selectively reacts with titanium nitride to enhance its removal rate while having minimal effect on silicon oxide, thus controlling the polishing selection ratio without requiring separate polishing processes for different films
2Productivity
If polishing composition is optimized for high removal rate of titanium nitride, then polishing efficiency improves, but removal rate of silicon oxide also increases
Solution Approach 1:
The invention applies local quality by making the polishing composition selectively reactive to specific film types through the use of organic acid. The composition is designed to have high chemical affinity and reactivity with titanium nitride while maintaining low reactivity with silicon oxide, achieving localized enhancement of polishing action on target materials only
Solution Approach 2:
By changing the pH parameter to 3 or lower and selecting specific organic acids with appropriate molecular weights (50-500), the invention creates optimal conditions for high-speed titanium nitride removal while suppressing silicon oxide removal, achieving both high productivity and high polishing selection ratio simultaneously
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 composition achieves a high polishing selection ratio of titanium nitride to silicon oxide, ensuring efficient and selective polishing of semiconductor substrates with improved removal rates and reduced defects.
Implementation Method 1
a polishing composition containing abrasive grains, an acid, a polishing inhibitor, and an oxidizing agent
Implementation Method 2
the oxidizing agent is hydrogen peroxide
Implementation Method 3
the polishing inhibitor contains a nonionic surfactant
Data Source
AI summary
There is provided a polishing composition capable of improving a polishing removal rate of a certain film type and suppressing a polishing removal rate of another certain film type, that is, capable of controlling a so-called polishing selection ratio, in an object to be polished containing two or more different film types. The present invention relates to a polishing composition containing abrasive grains, an acid, a polishing inhibitor, and an oxidizing agent, in which the abrasive grains have a positive zeta potential, the acid is an organic acid, the polishing inhibitor contains a nonionic surfactant, the oxidizing agent is hydrogen peroxide, and a pH of the polishing composition is 2 or more and 4 or less.