Semiconductor Wafer Cleaning Liquid Formulation for Copper Corrosion Inhibition
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Solution Overview
Problem
Current cleaning liquids for semiconductor wafers after the CMP step are inadequate in removing colloidal silica and organic residues while preventing copper corrosion, as they either fail to inhibit copper corrosion or are insufficient in removability due to poor component selection and ratios.
Innovation Solution
A cleaning liquid comprising specific components such as a compound represented by formula (1), alkylamine, polycarboxylic acid, ascorbic acid, and optionally histidine or its derivatives, with controlled mass ratios and pH levels, which form coordinate bonds to capture metal ions and prevent copper corrosion while enhancing organic residue removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an acidic aqueous solution is used as cleaning liquid, then copper corrosion is inhibited, but colloidal silica removal becomes difficult
Solution Approach 1:
The patent changes the pH parameter from acidic to alkaline range, and further optimizes it to specifically 13.0 or higher. This parameter change enables the cleaning liquid to simultaneously achieve both copper corrosion inhibition through ascorbic acid and effective colloidal silica removal through hydroxide ions and electrical repulsion forces.
Solution Approach 2:
The cleaning liquid is formulated as a composite solution containing multiple components: ascorbic acid (for copper protection), histidine (for organic residue removal), and alkaline substances like quaternary ammonium hydroxide or barium hydroxide (for colloidal silica removal). This composite formulation allows simultaneous achievement of multiple cleaning objectives that cannot be achieved with single-component solutions.
2Manufacturing precision
If an alkaline aqueous solution is used as cleaning liquid, then colloidal silica removal is enhanced, but copper corrosion inhibition becomes insufficient
Solution Approach 1:
Ascorbic acid acts as an intermediary substance that mediates between the alkaline environment (necessary for colloidal silica removal) and copper corrosion prevention. The ascorbic acid provides reducing and protective effects on copper surfaces even in highly alkaline conditions, enabling the system to maintain both high pH for silica removal and copper protection simultaneously.
Solution Approach 2:
The patent optimizes the pH parameter to be 13.0 or higher, which is sufficiently high to ensure effective colloidal silica removal through electrical repulsion and hydroxide ion action, while simultaneously maintaining copper corrosion inhibition through the presence of ascorbic acid and the formation of protective copper oxide passive films.
3Device complexity
If conventional cleaning liquids are used, then simple formulation is maintained, but organic residue removal becomes insufficient
Solution Approach 1:
The patent optimizes the concentration parameter of histidine to be 0.001 mass% or more, which provides sufficient chelating and solubilizing effects on organic residues including corrosion inhibitors and polishing additives. This concentration optimization ensures effective organic residue removal while maintaining formulation simplicity and avoiding excessive complexity in the cleaning liquid composition.
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 cleaning liquid effectively removes organic residues and prevents copper corrosion, ensuring the semiconductor wafer's integrity and preventing device malfunction by optimizing the mass ratios and pH of the components.
Implementation Method 1
the cleaning liquid... form coordinate bonds to capture metal ions and prevent copper corrosion
Implementation Method 2
The cleaning liquid effectively removes organic residues... by optimizing the mass ratios and pH of the components
Implementation Method 3
the cleaning liquid disclosed in Patent Literature 1 and Patent Literature 2 is poor in inhibitory effect of corrosion to copper or a compound containing copper because of not containing an ascorbic acid
Implementation Method 4
both the colloidal silica and the surface of the semiconductor wafer are negatively charged, an electrical repulsive force acts, and it becomes easy to remove the colloidal silica
Data Source
AI summary
The present invention relates to a cleaning liquid containing a component (A): a compound represented by the following formula (1), component (B): alkylamine, component (C): polycarboxylic acid, and component (D): ascorbic acid, in which a mass ratio of the component (A) to a total mass of the component (B) and the component (C) is 1 to 15, and in the formula (1), R1, R2, and R3 each have a definition same as the definition described in the description,