Dihydroxy Enolic CMP Slurry Stabilization
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Solution Overview
Problem
Chemical mechanical polishing (CMP) processes face challenges in achieving fast metal removal rates while minimizing wafer defects and metal ion contamination, particularly with the use of soluble metal oxidizers which lead to reduced shelf life and increased contamination of substrates.
Innovation Solution
The use of CMP compositions containing water, an abrasive material, a per-type oxidizer, a small amount of soluble metal-ion oxidizer bound to abrasive particles, and a dihydroxy enolic compound such as ascorbic acid, which stabilizes the slurry and reduces metal ion contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If soluble metal oxidizers are used to increase polishing rates, then material removal rate is improved, but metal ion contamination of substrates increases
Solution Approach 1:
The patent introduces dihydroxy enolic compounds as intermediary substances that mediate between the metal oxidizer and the substrate. These compounds complex with metal ions to form stable complexes, preventing direct metal ion deposition on the substrate while maintaining the oxidizing capability for metal removal, thus resolving the contradiction between high removal rate and low contamination
Solution Approach 2:
The patent changes the chemical state of metal ions by introducing dihydroxy enolic compounds that alter their solubility and reactivity parameters. This transforms free metal ions into stable complexes, changing their harmful properties while preserving the polishing function, thereby reducing contamination without sacrificing productivity
2Productivity
If soluble metal oxidizers are used to achieve fast polishing, then polishing rate is improved, but shelf life of slurry is reduced
Solution Approach 1:
Dihydroxy enolic compounds act as stabilizing intermediaries that prevent premature reactions between metal oxidizers and other slurry components. By complexing with metal ions, they maintain slurry stability during storage while enabling high polishing rates during use, thus extending shelf life without compromising productivity
Solution Approach 2:
The dihydroxy enolic compounds are pre-added to the slurry formulation to establish stable complexes with metal oxidizers before use. This preliminary complexation prevents degradation during storage, ensuring both long shelf life and high polishing performance when the slurry is actually applied
3Object-generated harmful factors
If chelators are used to reduce metal ion contamination, then contamination is reduced, but polishing rate decreases
Solution Approach 1:
The patent employs dihydroxy enolic compounds that change the chemical parameters of metal ion complexation, creating stable but not overly strong complexes. This optimization allows sufficient metal ion sequestration to reduce contamination while maintaining enough free metal ion activity to sustain high polishing rates, overcoming the trade-off between contamination control and productivity
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 provides increased polishing rates with reduced metal ion contamination and improved stability of the CMP slurry, extending its shelf life and minimizing the need for additional cleaning steps during semiconductor fabrication.
Implementation Method 1
a small amount of a chelator, b) a small amount of a dihydroxy enolic compound
Implementation Method 2
surface-modified colloidal abrasive polishing compositions and associated methods of using these compositions, particularly for chemical mechanical planarization, wherein the slurry comprises low levels of chelating free radical quenchers, non-chelating free radical quenchers, or both
Implementation Method 3
an oxidizer, preferably a per-type oxidizer
Implementation Method 4
optionally an abrasive material
Data Source
AI summary
A chemical mechanical polishing composition contains 1) water, 2) optionally an abrasive material, 3) an oxidizer, preferably a per-type oxidizer, 4) a small amount of soluble metal-ion oxidizer/polishing accelerator, a metal-ion polishing accelerator bound to particles such as to abrasive particles, or both; and 5) at least one of the group selected from a) a small amount of a chelator, b) a small amount of a dihydroxy enolic compound, and c) a small amount of an organic accelerator. Ascorbic acid in an amount less than 800 ppm, preferably between about 100 ppm and 500 ppm, is the preferred dihydroxy enolic compound. The polishing compositions and processes are useful for substantially all metals and metallic compounds found in integrated circuits, but is particularly useful for tungsten. The present invention also pertains to surface-modified colloidal abrasive polishing compositions and associated methods of using these compositions, particularly for chemical mechanical planarization, wherein the slurry comprises low levels of chelating free radical quenchers, non-chelating free radical quenchers, or both.