Quaternary Ammonium Salt Levelers for Copper Electrodeposition
Solution Overview
Problem
Current copper plating chemistries struggle to achieve defect-free copper deposition with uniform surface topography across a wide range of feature dimensions and aspect ratios, particularly for semiconductor applications, where achieving high deposition rates and maintaining yield is challenging, especially for features with dimensions from 10 μm to 200 μm.
Innovation Solution
Incorporation of quaternary ammonium salts of dialkylaminoalkyl esters of 10-thiaxanthenecarboxylic acid and its derivatives as levelers in the electrolytic copper plating chemistry, which enables excellent leveling effects over a wide range of feature aspect ratios and high current densities, producing copper pillars and RDLs with flat or convex topography in a single bath composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional copper plating chemistry is used, then copper deposition can be achieved, but uniform surface topography and defect-free deposition cannot be maintained across wide range of feature dimensions and aspect ratios
Solution Approach 1:
The patent modifies the chemical parameters of the plating bath by incorporating specific organic additives (suppressors, levelers, and brighteners) with controlled concentrations. These parameter changes enable the plating chemistry to adapt to different feature dimensions and aspect ratios while maintaining uniform surface topography and defect-free deposition across the entire range from 10 μm to 200 μm features.
Solution Approach 2:
The patent employs a composite plating chemistry formulation containing multiple organic additives working synergistically: suppressors (e.g., polyether-based compounds) to control deposition rate, levelers (e.g., carboxylic acid derivatives) to flatten surface irregularities, and brighteners to enhance surface reflectivity. This composite approach resolves the contradiction by enabling both precision and versatility simultaneously.
2Productivity
If high current densities are used to increase deposition rate, then manufacturing throughput increases, but leveling effect deteriorates
Solution Approach 1:
The patent uses dynamic levelers that can adapt their performance based on local current density conditions. These levelers remain effective across varying current densities by dynamically adjusting their adsorption behavior on the substrate surface, allowing high deposition rates to be achieved while maintaining leveling effect through real-time adaptation to changing plating conditions.
Solution Approach 2:
The plating chemistry incorporates additives that provide feedback mechanisms through preferential adsorption on protruding features. As deposition proceeds at high current densities, the levelers continuously adsorb on developing surface irregularities, providing negative feedback that prevents dendrite formation and maintains uniform topography even at elevated deposition rates of 10 ASD or higher.
3Adaptability or versatility
If multiple copper plating chemistries are used to cover full range of feature dimensions, then all customer requirements can be met, but manufacturing cost increases
Solution Approach 1:
The patent develops a universal copper plating chemistry formulation that performs multiple functions simultaneously: it effectively plates features across the entire dimension range from 10 μm to 200 μm, maintains uniform surface topography, achieves high deposition rates, and works for various semiconductor applications including copper pillars, RDLs, and TSVs. This single versatile chemistry eliminates the need for multiple specialized formulations, thereby reducing manufacturing costs while maintaining full adaptability.
4Manufacturing precision
If conventional levelers are used, then some leveling effect is achieved, but toxic by-products are generated that affect bath stability
Solution Approach 1:
The patent replaces conventional toxic levelers with environmentally friendly alternatives based on biodegradable organic compounds such as carboxylic acid derivatives and their salts. These new levelers provide comparable or superior leveling effects while decomposing into non-toxic by-products that do not adversely affect bath stability, thereby resolving the contradiction between achieving precision and avoiding harmful emissions.
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
This approach allows for the production of copper pillars and RDLs with uniform surface morphology and high within-die uniformity, achieving deposition rates of up to 10 ASD (2.2 μm/min) across a broad range of feature sizes, reducing manufacturing costs and increasing productivity.
Implementation Method 1
Incorporation of quaternary ammonium salts of dialkylaminoalkyl esters of 10-thiaxanthenecarboxylic acid and its derivatives as levelers in the electrolytic copper plating chemistry
Implementation Method 2
electrolytic copper deposition chemistry
Implementation Method 3
applying an electrical current to the electrolytic deposition composition to deposit a metal onto the substrate
Data Source
AI summary
The present application discloses a levelling compound for electrodepositing metals. The metal is of formula (II):