Intermittent Plating Current for High-Aspect Ratio Vias
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Solution Overview
Problem
Existing electroplating methods face challenges in securely and efficiently filling copper into deep high-aspect ratio vias in semiconductor substrates without producing defects like voids, due to insufficient metal ion supply and fluctuations in current density.
Innovation Solution
An electroplating method involving intermittent plating current supply with increasing current supply time and decreasing current stop time as the plating progresses, maintaining a constant current value and average current density to promote bottom-up growth and prevent void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous electroplating is performed at high current density to increase productivity, then plating speed increases, but metal ion depletion occurs in via bottoms causing void formation and poor filling quality
Solution Approach 1:
The patent applies periodic pulsed current instead of continuous current, using ON/OFF cycles that allow metal ion diffusion during OFF periods while maintaining plating progress during ON periods. This resolves the contradiction by enabling both reasonable plating speed and adequate ion supply to via bottoms.
Solution Approach 2:
The patent dynamically adjusts current density throughout the plating process, starting high to promote bottom-up growth and gradually reducing it as via filling progresses. This dynamic adjustment maintains filling quality while achieving acceptable productivity.
2Productivity
If high current density is used to reduce plating time, then productivity increases, but additive decomposition accelerates reducing plating uniformity
Solution Approach 1:
Pulsed current with controlled duty cycles limits the cumulative exposure of additives to high current density, reducing decomposition while maintaining effective plating speed. The periodic nature allows additive regeneration during OFF periods.
Solution Approach 2:
The patent changes current density as a time-dependent parameter, using high initial current density to promote bottom-up growth then gradually reducing it. This parameter evolution maintains additive stability while achieving filling objectives.
3Stability of the object's composition
If current density is reduced to maintain additive stability, then additive decomposition decreases, but plating speed reduces affecting productivity
Solution Approach 1:
The pulsed current regime allows high current density to be applied intermittently without continuous additive exposure. The periodic ON/OFF cycling maintains both additive stability and acceptable plating speed by limiting cumulative additive consumption.
4Manufacturing precision
If high current density is applied initially to promote bottom-up growth, then via filling improves, but additive consumption increases causing later plating defects
Solution Approach 1:
The patent implements time-dependent current density profiling, starting high to establish bottom-up growth then progressively reducing it. This parameter evolution achieves superior via filling while controlling cumulative additive consumption throughout the extended plating process.
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 method ensures secure and efficient filling of copper into deep high-aspect ratio vias with uniform thickness, preventing voids and maintaining additive stability, thereby improving the quality of the plated metal.
Implementation Method 1
the metal ion concentration of the plating solution significantly decreases in the bottoms of the vias because of insufficient supply of metal ions by ion diffusion
Implementation Method 2
copper electroplating is carried out on the surface of the substrate W using the copper seed layer 16 as a cathode, thereby filling a plated metal (copper) 18 into the vias 12
Data Source
AI summary
An electroplating method can securely and efficiently fill a plated metal into deep high-aspect ratio vias in a bottom-up manner without producing defects in the plated metal. The electroplating method includes: immersing a substrate, having vias formed in a surface, and an anode in a plating solution in a plating tank, the anode being disposed opposite the surface of the substrate; and intermittently passing a plating current at a constant current value between the substrate and the anode in such a manner that the supply and the stop of the plating current are repeated, and that the proportion of a current supply time during which the plating current is supplied increases with the progress of plating, thereby filling a plated metal into the vias.