Amine-Alcohol Additive for CMP Slurry Stability
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Solution Overview
Problem
The repeated use of polishing slurry in silicon wafer CMP processes leads to a significant decrease in polishing rate and variability, necessitating frequent replacements and increased costs, which can be mitigated by adding inorganic alkali solutions but results in inconsistent polishing rates.
Innovation Solution
An additive comprising one or more amine compounds, preferably including a quaternary ammonium salt and an alcohol, is added to the polishing composition to stabilize polishing properties and prevent precipitation, thereby maintaining consistent polishing rates and reducing the need for frequent slurry replacements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If inorganic alkali solution is added to circulating slurry to prevent decrease of polishing rate, then polishing rate is maintained, but polishing rate varies widely before and after addition
Solution Approach 1:
The invention changes the chemical parameters of the slurry by using amine compounds (organic bases) instead of inorganic alkalis. The amine compounds gradually neutralize accumulated acid components through chemical reactions, maintaining pH within a stable range (9-11) and ensuring consistent polishing rates without the wide variations caused by inorganic alkali additions.
Solution Approach 2:
The invention uses inexpensive amine compounds that can be added in small quantities to continuously regenerate the slurry's polishing properties. This approach replaces the need for frequent complete slurry replacements while maintaining stable performance, effectively using small amounts of additive to extend slurry life.
2Productivity
If slurry is replaced frequently to maintain polishing properties, then polishing rate is maintained, but process interruptions increase and costs increase
Solution Approach 1:
The invention enables continuous useful action by allowing the slurry to be used repeatedly with periodic amine compound additions. This maintains polishing properties throughout the slurry's lifecycle, eliminating the need for frequent complete replacements and ensuring continuous production without interruptions.
Solution Approach 2:
Instead of discarding the entire slurry when properties degrade, the invention recovers and regenerates the slurry by adding amine compounds to neutralize acid accumulation. This extends slurry service life significantly, reducing replacement frequency and associated process interruptions.
3Productivity
If inorganic alkali solution is added to maintain polishing properties, then polishing rate decrease is prevented, but addition costs increase
Solution Approach 1:
The invention uses inexpensive amine compounds (such as ammonia water, organic amines) that can be added in small quantities to continuously regenerate slurry properties. These cheap additives extend slurry life without requiring large quantities, reducing both material costs and handling requirements compared to inorganic alkalis.
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 additive maintains stable polishing properties and reduces the variation in polishing rates, preventing precipitation of amine compounds and minimizing the quantity of additives required, thus reducing costs and process interruptions.
Implementation Method 1
the decrease of pH and polishing properties of slurry... By adding the inorganic alkali solution such as potassium hydroxide or sodium hydroxide... it is possible to prevent the decrease of an average polishing rate
Implementation Method 2
comprising one or more amine compounds and an alcohol... preventing precipitation of amine compounds
Data Source
AI summary
The invention relates to an additive for polishing composition, which can ensure stable polishing properties. The additive for polishing composition contains one or more amine compounds and an alcohol. The one or more amine compounds contain a quaternary ammonium salt. When the one or more amine compounds are contained in high concentration, the occurrence of precipitation of the amine compound can be prevented by including the alcohol.