Copper Bump Electrodeposition Composition for Uniform Void-Free Filling
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Solution Overview
Problem
The challenge in the semiconductor industry is to form copper bumps with good morphology, low roughness, and uniform height for improved connectivity in high-density integrated circuits, while avoiding defects such as voids, particularly in recessed features ranging from 500 nanometers to 500 micrometers.
Innovation Solution
A copper electroplating composition is developed using polyalkyleneimine additives with a specific molecular weight and oxyalkylene substitution, which provides a leveling effect to achieve uniform copper deposits with low roughness and reduced defects, suitable for filling recessed features of various sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional copper electroplating is used to form bumps, then copper deposits can be formed, but the deposits exhibit high roughness and poor coplanarity, particularly in recessed features
Solution Approach 1:
The patent changes the chemical parameters of the electroplating bath by introducing polyalkyleneimine leveling agents with specific molecular weights (900-100,000 g/mol) and structures. These additives modify the deposition kinetics and surface chemistry, enabling uniform copper deposits with low roughness and high coplanarity even in recessed features, directly resolving the contradiction between achieving precision and maintaining smooth morphology
Solution Approach 2:
The polyalkyleneimine compounds act as intermediary substances between the copper ions and the substrate surface. These leveling agents adsorb preferentially on protruding areas and regulate copper deposition, serving as a mediating layer that enables uniform filling of recessed features while maintaining overall coplanarity and low surface roughness
2Productivity
If copper bumps are formed with high density and small size, then connection density increases, but positioning accuracy and bonding reliability become more difficult to ensure
Solution Approach 1:
By optimizing the electroplating parameters through polyalkyleneimine additives, the patent achieves uniform copper deposit height and excellent coplanarity across high-density bump arrays. The leveling agents ensure that even as bump size decreases and density increases, each bump forms with precise dimensional control and uniform height, maintaining positioning accuracy throughout the wafer
Solution Approach 2:
The patent creates equipotential conditions across the wafer surface by using polyalkyleneimine leveling agents that distribute copper deposition uniformly. This ensures that all bumps, regardless of their position or local variations in the substrate, achieve the same height and morphology, thereby maintaining positioning accuracy and bonding reliability in high-density configurations
3Manufacturing precision
If electroplating is performed to fill recessed features, then copper deposits can be formed, but voids and defects are generated in the deposits
Solution Approach 1:
The polyalkyleneimine leveling agents are pre-added to the electroplating bath before deposition begins. These additives preemptively adsorb on the substrate surface and establish a controlled deposition environment that prevents void formation from the outset, ensuring defect-free filling of recessed features while achieving uniform deposition height
Solution Approach 2:
The patent modifies the electrochemical parameters of the plating bath by incorporating polyalkyleneimine compounds at specific concentrations. This changes the deposition mechanism to enable progressive, void-free filling of recessed features from bottom to top, while simultaneously achieving uniform copper height across the entire wafer surface without defects
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 ensures improved coplanarity and conductivity of copper deposits, facilitates high plating rates, and reduces impurities, enabling void-free filling of recessed features with enhanced connectivity.
Implementation Method 1
A copper electroplating composition is developed using polyalkyleneimine additives with a specific molecular weight and oxyalkylene substitution, which provides a leveling effect to achieve uniform copper deposits with low roughness
Data Source
AI summary
Disclosed herein is a composition for copper bump electrodeposition 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 900 g/mol to 100 000 g/mol,(b) the N-hydrogen atoms are each substituted by a C2 to C6 polyoxyalkylene group, and(c) the average number of oxyalkylene units in the polyoxyalkylene group is from more than 10 to less than 30 per N-hydrogen atoms in the polyalkyleneimine.