Polyalkyleneimine Leveling Agent for Void-Free Copper Electroplating
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Solution Overview
Problem
The electronic industry faces challenges in achieving uniform and defect-free copper electroplating for semiconductor bumps, particularly in filling recessed features with high aspect ratios and maintaining low roughness and coplanarity, which is crucial for increasing connection density and reliability in semiconductor devices.
Innovation Solution
A copper electroplating composition comprising polyalkyleneimine additives with specific molecular weight ranges and polyoxyalkylene modifications, which act as leveling agents to provide uniform copper deposits with low roughness and improved coplanarity, capable of filling recessed features from 500 nm to 500 μm without forming voids, and facilitating high plating rates at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional copper electroplating is used to fill recessed features, then copper deposition occurs, but voids form and coplanarity deteriorates
Solution Approach 1:
The patent applies different functional properties to different parts of the electroplating system: suppressors with high molecular weight (≥10,000 g/mol) provide bottom-up filling by adsorbing on copper surfaces to suppress deposition, while accelerators promote copper ion reduction. This local differentiation of additive functions enables void-free filling and improved coplanarity in recessed features
Solution Approach 2:
The patent changes critical parameters including suppressor molecular weight (≥10,000 g/mol, preferably ≥50,000 g/mol), suppressor concentration (0.1-10 ppm), and copper ion concentration (20-100 g/L). These parameter changes optimize the electroplating process to achieve uniform copper deposits without voids and with excellent coplanarity
2Productivity
If high current density is applied to increase plating rate, then productivity improves, but deposit roughness increases and coplanarity deteriorates
Solution Approach 1:
The patent introduces organic suppressors as intermediary substances that mediate between the electric field and copper deposition. These suppressors adsorb on copper surfaces and modulate the electroplating reaction, enabling high current density operation while maintaining smooth deposits and uniform coplanarity. The suppressor acts as a buffer that prevents excessive copper ion reduction at high current densities
3Quantity of substance
If recessed features with small aperture sizes are filled, then connection density increases, but void formation increases and filling completeness deteriorates
Solution Approach 1:
The patent applies bottom-up filling methodology where suppressors with high molecular weight selectively adsorb on copper surfaces to control deposition locally. This creates a filling pattern that progresses from bottom to top, ensuring complete filling of narrow recessed features with aperture sizes from 1 to 200 μm without void formation, thereby achieving high connection density with excellent filling completeness
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 improved coplanarity and reduced impurities in copper deposits, enabling high connection density and reliability by ensuring uniform deposition and minimizing defects, such as voids, while maintaining high conductivity and allowing for elevated temperature plating.
Implementation Method 1
copper electroplating composition comprising a polyethyleneimine leveling agent
Implementation Method 2
leveling agent adsorbs onto the copper surface during electrodeposition to regulate copper ion reduction
Data Source
AI summary
Disclosed herein is a composition including copper ions and at least one additive including a polyalkyleneimine backbone including N-hydrogen atoms, where(a) the polyalkyleneimine backbone has a mass average molecular weight MW of from 600 g/mol to 100 000 g/mol,(b) the N-hydrogen atoms are each substituted by a polyoxyalkylene group including an oxyethylene and a C3 to C6 oxyalkylene unit, and(c) the average number of oxyalkylene units in the polyoxyalkylene groups is of from more than 10 to less than 30 per N-hydrogen atom in the polyalkyleneimine.