Polyalkanolamine Levelers for Uniform Copper Bump Electroplating
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Solution Overview
Problem
Existing copper electroplating processes struggle to achieve uniform and defect-free deposition of copper bumps on semiconductor wafers, particularly in recessed features with micrometer-scale dimensions, while maintaining low roughness and high conductivity.
Innovation Solution
The use of specific polyalkanolamines as leveling agents in copper electroplating compositions, which provide improved coplanarity and reduced defects by enhancing the leveling properties, allowing for uniform copper deposition in features ranging from 500 nm to 500 μm without voids and with low roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electroplating processes are used, then copper bumps can be formed, but uniform deposition and low roughness cannot be achieved simultaneously
Solution Approach 1:
A polyalkylene oxide compound is introduced as an intermediary additive in the electroplating solution to mediate between the copper ions and the substrate surface. This intermediary substance adsorbs preferentially on high-curvature regions and defect sites, suppressing excessive copper deposition in these areas and promoting uniform growth, thereby achieving both uniform deposition and low surface roughness simultaneously
Solution Approach 2:
The electroplating process parameters are optimized by controlling the concentration of polyalkylene oxide compound (0.01-10 ppm), current density (0.1-10 ASD), temperature (10-50°C), and pH (0.5-3.0) to achieve the optimal balance between deposition rate, uniformity, and surface finish. These parameter changes enable simultaneous achievement of uniform deposition and low roughness
2Productivity
If high plating rates are used, then productivity increases, but deposition uniformity deteriorates
Solution Approach 1:
The polyalkylene oxide compound acts as a mediator that remains effective across a wide range of current densities. It suppresses the tendency for non-uniform deposition that normally occurs at high plating rates, allowing the process to maintain both high productivity and uniform deposition by adsorbing on protruding regions and preventing excessive growth even under high current conditions
Solution Approach 2:
The electroplating process employs dynamic control of current density with time, using pulse plating or reverse pulse plating techniques in combination with the polyalkylene oxide additive. This dynamic approach allows high average plating rates while the additive ensures uniform deposition by suppressing peaks and valleys formation during the plating cycle
3Quantity of substance
If electroplating is performed on recessed features, then copper bumps can be formed, but voids and defects are generated
Solution Approach 1:
The polyalkylene oxide compound exhibits local quality effects by preferentially adsorbing on surfaces with different curvatures. On recessed features, it adsorbs on the sidewalls and suppresses deposition there, while allowing preferential filling from the bottom up. This local differentiation of deposition behavior enables complete filling of recesses without void formation, achieving defect-free copper bumps
Solution Approach 2:
The polyalkylene oxide compound is pre-added to the electroplating solution before the plating process begins, allowing it to pre-adsorb on the substrate surface including recessed features. This preliminary action prepares the surface by creating a controlled adsorption layer that guides subsequent copper deposition, preventing void formation before it occurs and ensuring reliable defect-free bumps
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 polyalkanolamines facilitate high plating rates and reduced impurities, resulting in copper deposits with improved conductivity and uniformity, suitable for semiconductor applications.
Implementation Method 1
copper is deposited by copper electroplating on the exposed surface of the seed layer in the openings to thereby form copper bumps
Implementation Method 2
copper electroplating composition comprising the polyalkanolamines... for copper bump electrodeposition
Data Source
AI summary
Disclosed herein is a A polyalkanolamine including the structure of formula L1[AL]n[BL]m (L1)whereinXL1, XL2, XL3 are independently selected from a C1 to C6 alkanediyl;ArL is a 5 or 6 membered N-heteroaromatic ring system including from 1 to 4 N atoms, which may be unsubstituted or substituted by C1 to C6 alkyl;n is an integer of from 2 to 350;m is 0 or an integer of from 1 to 600;o is 1 or an integer of from 2 to 25;BL1 is a continuation of the backbone BL by branching;XL11, XL12, XL13 are independently selected from a C1 to C6 alkanediyl;XL21 is a C1 to C6 alkanediyl;and derivatives thereof obtainable by N-protonation, N-quaternization, substitution, or polyalkoxylation.