Magnetic Structure for Semiconductor Wafer Plating Uniformity
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Solution Overview
Problem
The metal plating process on semiconductor wafers often results in non-uniformity due to a terminal effect, where the electrical plating current is higher at the wafer edge than the center, leading to uneven metal atom accumulation.
Innovation Solution
A magnetic structure is used to modify the electrical plating current by applying a force to metal ions, either moving them away from the wafer edge or towards the center, to equalize the current values between the edge and center, thereby promoting uniform metal plating across the wafer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrical plating current is supplied to electroplate metal onto semiconductor wafer, then metal atoms accumulate on wafer surface, but non-uniform accumulation occurs due to terminal effect causing higher current at wafer edge than center
Solution Approach 1:
The patent introduces a magnetic structure that creates a non-uniform magnetic field with different field strengths at different locations on the wafer. The magnetic field is stronger at the wafer center and weaker at the edges, which locally modifies the plating current distribution to compensate for the terminal effect. This local quality adjustment ensures uniform metal accumulation across the entire wafer surface despite the inherent resistance gradient.
Solution Approach 2:
The patent changes the physical parameters of the plating system by introducing a magnetic field with specific flux density values (e.g., 0.1-1.0 Tesla at wafer center). This parameter change affects the Lorentz force acting on metal ions, thereby modifying their transport and deposition behavior. By controlling the magnetic field strength and distribution, the system achieves uniform current density and uniform metal plating across the wafer.
2Manufacturing precision
If magnetic structure is introduced to modify plating current, then uniform metal accumulation is achieved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical current distribution control systems with a magnetic field-based approach. Instead of using mechanical means to adjust electrode positions or modify current paths, the system uses a magnetic structure (such as permanent magnets or electromagnets) to generate a magnetic field that naturally redistributes the plating current. This substitution simplifies the overall system architecture while achieving the desired uniformity.
Solution Approach 2:
The magnetic structure serves as an intermediary between the power source and the wafer surface. Rather than directly controlling current distribution through complex electrical circuits, the magnetic field acts as a mediator that indirectly influences metal ion transport and deposition. This intermediary approach provides a simpler, more elegant solution compared to direct electrical control methods.
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 magnetic structure ensures that metal atoms accumulate uniformly across the semiconductor wafer, mitigating the terminal effect and achieving conformal metal plating profiles.
Implementation Method 1
A magnetic structure is used to modify the electrical plating current by applying a force to metal ions
Implementation Method 2
The electrical plating current provides electrons that convert metal ions to metal atoms that accumulate on the surface of the semiconductor wafer
Data Source
AI summary
Among other things, one or more systems and techniques for promoting metal plating profile uniformity are provided. A magnetic structure is positioned relative to a semiconductor wafer that is to be electroplated with metal during a metal plating process. In an embodiment, the magnetic structure applies a force that decreases an edge plating current by moving metal ions away from a wafer edge of the semiconductor wafer. In an embodiment, the magnetic structure applies a force that increases a center plating current by moving metal ions towards a center portion of the semiconductor wafer. In this way, the edge plating current has a current value that is similar to a current value of the center plating current. The similarity between the center plating current and the edge plating current promotes metal plating uniformity.