Chemical Mechanical Polishing Method Using Alkaline Slurry and Acid Buffer
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Solution Overview
Problem
Conventional Chemical Mechanical Polishing (CMP) processes in the semiconductor industry face challenges in removing residual metallic oxide, metallic hydroxide, and metallic oxide silicide residues, which affect the manufacturing yield and long-term reliability of semiconductor devices due to their low solubility in deionized water and potential corrosion of the device surface.
Innovation Solution
A CMP method involving an alkaline grinding slurry with silica particles and an alkaline H2O2 solution for polishing, followed by an acid buffer, such as an organic acid compound, to remove residual layers, and forming a passivation layer to prevent oxidation, ensuring excellent surface planarity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If deionized water is used to remove residual layer, then cleaning process is simple, but residual metallic oxide and metallic hydroxide cannot be effectively removed
Solution Approach 1:
The patent changes the chemical parameter (pH) of the cleaning solution from neutral (deionized water) to acidic (pH 2-4 acid buffer), enabling effective removal of metallic oxide and hydroxide residues while maintaining surface planarity
Solution Approach 2:
The patent introduces an acid buffer as an intermediary substance between the residual layer and deionized water, facilitating the removal of water-insoluble metallic oxides and hydroxides by converting them into water-soluble forms
2Productivity
If acid grinding slurry is used to grind device layer, then polishing can be performed, but surface corrosion occurs and manufacturing yield decreases
Solution Approach 1:
The patent inverts the conventional approach by using alkaline grinding slurry instead of acid grinding slurry, achieving effective polishing while preventing surface corrosion and improving manufacturing yield
Solution Approach 2:
The patent changes the pH parameter of the grinding slurry from acidic to alkaline, fundamentally altering the chemical interaction with the device layer to eliminate corrosion while maintaining polishing effectiveness
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 method effectively removes residual layers, prevents surface oxidation, and enhances the manufacturing yield and long-term reliability of semiconductor devices by using an acid buffer to dissolve metal ions and forming a passivation layer that protects the polished surface.
Implementation Method 1
an alkaline H2O2 solution for polishing
Implementation Method 2
an acid buffer, such as an organic acid compound, to remove residual layers
Data Source
AI summary
A chemical mechanical polishing method includes providing a device layer having a surface to be polished, polishing the surface using an alkaline grinding slurry, removing a residual layer that is been formed on the polished surface using an acid buffer, forming a passivation layer covering the polished surface of the device layer after the residual layer has been removed, and cleaning the passivation layer using deionized water. A semiconductor device thus fabricated has surfaces with excellent flatness, good manufacturing yield and long-term reliability.