Post-CMP Cleaning Composition for Semiconductor Defect Reduction
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Solution Overview
Problem
Current CMP slurries using metal-based inorganic oxidizers like KMnO4 lead to pad staining and high defect counts due to metal oxide species precipitation, and oxide abrasives cause adsorption of particles on semiconductor surfaces, making post-CMP cleaning challenging.
Innovation Solution
A cleaning composition comprising reducing agents with a standard reduction potential less than 1.224 V, particle removal agents such as citric acid or aminophosphonic acids, and surfactants like carboxylic acid surfactants is used to remove pad stains and particles from semiconductor surfaces, effectively reducing defect counts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metal-based inorganic oxidizers (e.g., KMnO4) are used in CMP slurries to enhance film removal rates, then the film removal rate is improved, but metal oxide species precipitate on the polishing surface causing pad staining and high defect counts
Solution Approach 1:
The patent extracts and removes the harmful metal oxide species (MnO2) from the polishing surface using a dedicated cleaning composition containing reducing agents. This separates the film removal function (performed by KMnO4 during polishing) from the stain removal function (performed by the cleaning composition), allowing both to coexist without compromising each other.
Solution Approach 2:
The patent changes the chemical parameters of the cleaning composition by using reducing agents with specific standard reduction potentials (E° < 1.224 V) to convert insoluble metal oxide stains into soluble forms that can be easily removed. This parameter-based approach targets the chemical nature of the staining problem.
2Productivity
If oxide abrasives (e.g., ZrO2, CeO2) are contained in CMP slurries to improve polishing performance, then the polishing performance is enhanced, but oxide abrasives adsorb onto semiconductor surfaces creating post-CMP particle defects
Solution Approach 1:
The patent converts the harmful adsorbed oxide particles into removable substances by using chelating agents in the cleaning composition that specifically bind to metal oxide particles. The same oxide abrasives that provide polishing benefits are now targeted and removed by the cleaning composition, turning the harmful effect into a manageable cleaning task.
Solution Approach 2:
The patent introduces chelating agents as intermediary substances that mediate between the adsorbed oxide particles and the cleaning process. These agents act as intermediaries that selectively bind to metal oxide particles, facilitating their removal without affecting the semiconductor substrate or requiring harsh cleaning methods.
3Ease of operation
If traditional ammonia-containing washing solutions are used for post-CMP cleaning to remove particles, then some particle removal is achieved, but the cleaning effectiveness is insufficient and defect counts remain high
Solution Approach 1:
The patent fundamentally changes the chemical parameters of the cleaning solution by incorporating reducing agents with specific reduction potentials, chelating agents, and surfactants. This multi-component chemical system provides superior cleaning effectiveness compared to simple ammonia rinses, achieving defect counts of 20 or less while maintaining operational simplicity.
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 significantly reduces post-CMP defect counts, with defect counts often reaching 0 or less than 20, and effectively removes MnO2 pad stains, outperforming traditional ammonia rinses in defect reduction.
Implementation Method 1
one or more reducing agents; the one or more reducing agents yields a standard reduction potential (Eo) of less than 1.224 V
Implementation Method 2
a surfactant
Implementation Method 3
a particle removal agent; the particle removal agent is citric acid, amino acid, or aminophosphonic acid
Data Source
AI summary
Polishing compositions are disclosed for simultaneously removing particles from a surface that has been polished using a CMP slurry comprising a polishing rate accelerator and removing a pad stain from a polishing pad that has been contacted with a CMP slurry comprising a polishing rate accelerator.Cleaning compositions for post-CMP cleaning of semiconductor surfaces, comprise one or more reducing agents, a particle removal agent, a surfactant, and a base. When one or more reducing agents yields a standard reduction potential of less than 1.224 V, the cleaning composition of the present disclosure is able to remove a MnO2 pad stain from a polishing pad and reduce defects on a polished surface (by removing particles).