Post-CMP Cleaning Formulation for Copper and Low-k Dielectrics
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Solution Overview
Problem
Current methods for cleaning microelectronic devices struggle to effectively remove residues and contaminants, particularly from copper, tantalum, and ruthenium-containing materials, which can lead to poor adhesion and electrical performance issues due to the high resistivity of these materials and the complexity of their layers.
Innovation Solution
A cleaning composition comprising organic amines, water, pH adjusting agents, organic additives, and metal corrosion inhibitors is used to contact the microelectronic devices, effectively removing post-CMP, post-etch, and post-ash residues while being compatible with copper, low-k dielectric materials, and barrier materials like tantalum, cobalt, and ruthenium-containing materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cleaning methods are used to remove residues from microelectronic devices, then some residue removal is achieved, but the cleaning efficacy is insufficient (less than 90%) and may damage the underlying materials
Solution Approach 1:
The cleaning composition uses specific pH ranges (adjusted by pH adjusting agents) and controlled concentrations of organic additives and corrosion inhibitors to optimize cleaning efficacy while preventing material damage. The parameters of the cleaning solution are carefully controlled to achieve at least 90% residue removal without corroding copper, tantalum, or ruthenium materials.
Solution Approach 2:
The cleaning composition is a multi-component formulation combining organic amines, water, pH adjusting agents, organic additives, and metal corrosion inhibitors. This composite approach allows the solution to effectively remove residues while the corrosion inhibitors protect the underlying metal materials from damage.
2Reliability
If barrier layers are used to prevent copper diffusion, then device contamination is prevented, but copper deposition becomes difficult due to high resistivity of tantalum
Solution Approach 1:
A copper seed layer is introduced as an intermediary between the tantalum barrier layer and the copper plating process. This seed layer facilitates copper deposition by providing a conductive base that overcomes the high resistivity of tantalum, enabling subsequent copper plating while maintaining the barrier function of the tantalum layer.
Solution Approach 2:
The barrier layer structure is designed with different local properties: the tantalum barrier layer provides contamination prevention, while the copper seed layer provides local conductivity for deposition. This local differentiation allows both functions to coexist without compromising either contamination prevention or copper deposition.
3Manufacturing precision
If seed layer thickness is reduced to prevent overhang and void formation, then patterning accuracy is improved, but adhesion and electrical performance may be compromised
Solution Approach 1:
The cleaning composition is applied before copper plating to thoroughly remove residues and contaminants from the barrier layer surface. This preliminary cleaning action ensures that even thin seed layers can achieve adequate adhesion and electrical performance by eliminating surface contaminants that would otherwise compromise these properties.
Solution Approach 2:
The cleaning process uses optimized pH and chemical composition to selectively remove contaminants without etching or damaging the thin seed layer. This parameter control allows the seed layer to maintain its reduced thickness for patterning accuracy while achieving sufficient adhesion and electrical performance through improved surface cleanliness.
4Shape
If CMP slurry is used for planarization, then surface flatness is achieved, but residues and contaminants remain that can roughen copper metallization
Solution Approach 1:
The cleaning composition specifically targets and removes CMP slurry residues, corrosion inhibitor compounds, and particles from the planarized surface. This extraction of harmful residues prevents subsequent copper roughening while preserving the surface flatness achieved by CMP.
Solution Approach 2:
The cleaning process converts the potentially harmful residues left by CMP into removable contaminants. By designing the cleaning composition to specifically target these residues, the harmful effect of slurry contamination is transformed into a removable substance that can be efficiently cleaned away, actually benefiting the final copper metallization quality.
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 achieves a substantial removal of residues and contaminants, with at least 90% efficacy, preventing corrosion and ensuring smooth electrical performance by maintaining the integrity of the microelectronic device surfaces.
Implementation Method 1
The residue may include post-CMP, post-etch, and/or post-ash residue... effectively removing post-CMP, post-etch, and post-ash residues
Implementation Method 2
Chemical Mechanical Polishing or Planarization (CMP) is a process in which material is removed from a surface of a microelectronic device wafer, and the surface is planarized and polished by coupling a physical process such as abrasion with a chemical process such as oxidation or chelation
Implementation Method 3
A cleaning composition comprising organic amines, water, pH adjusting agents, organic additives, and metal corrosion inhibitors
Implementation Method 4
at least one metal corrosion inhibitor... preventing corrosion and ensuring smooth electrical performance
Data Source
AI summary
A cleaning composition and process for cleaning post-chemical mechanical polishing (CMP) residue and contaminants from a microelectronic device having said residue and contaminants thereon. The composition achieves highly efficacious cleaning of the post-CMP residue and contaminant material from the surface of the microelectronic device without compromising the low-k dielectric material or the copper interconnect material. In addition, the cleaning compositions are compatible with ruthenium-containing materials.