Electroplating Dynamic Edge Control via Segmented Thief Electrodes
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Solution Overview
Problem
Conventional electroplating methods for semiconductor wafers face challenges in achieving uniformity of metal deposition at the wafer edge, particularly due to non-uniform patterns and regions like the notch or scribe, leading to variations in plating thickness and quality.
Innovation Solution
The use of a plurality of thief electrodes with independently adjustable current channels around the wafer edge, allowing for dynamic control of current density based on the wafer's rotational position to ensure uniform electroplating thickness and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single thief electrode is used to control plating thickness at the wafer edge, then the terminal effect on thin seed layers can be controlled, but uniformity of electroplating across the wafer edge cannot be achieved due to non-uniform patterns like notch or scribe
Solution Approach 1:
The single thief electrode is divided into multiple segmented thief electrodes (first thief electrode, second thief electrode, etc.) distributed around the wafer edge. Each segment can be independently controlled to address local non-uniformities caused by features like notch or scribe regions, thereby achieving uniform plating thickness across the entire wafer edge.
Solution Approach 2:
Different thief electrode segments are assigned different current levels based on their local position relative to wafer features. For example, thief electrodes positioned near the notch or scribe regions can be adjusted to provide localized compensation, ensuring that each region receives appropriate current control for uniform plating.
2Manufacturing precision
If the electrolyte bath conductivity is increased to improve plating quality, then the terminal effect on thin seed layers increases, but control over plating thickness becomes more difficult
Solution Approach 1:
The thief electrode system is segmented into multiple independently controllable units positioned around the wafer edge. This segmentation allows the system to effectively manage the increased terminal effect caused by high conductivity electrolytes by distributing the control function across multiple zones, preventing any single region from experiencing excessive current density.
3Quantity of substance
If thin seed layers are used for RDL and WLP plated wafers to reduce material cost, then the terminal effect increases, but achieving uniform plating thickness becomes more challenging
Solution Approach 1:
The thief electrode is divided into multiple segments that can be independently controlled. This segmentation allows for precise local adjustment of current density at the wafer edge, compensating for the increased terminal effect that occurs with thin seed layers and ensuring uniform plating thickness despite the reduced seed layer thickness.
Solution Approach 2:
Different segments of the thief electrode provide localized current control tailored to specific regions of the wafer edge. This local quality approach ensures that areas with thin seed layers receive appropriate current management to maintain uniform plating thickness throughout.
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 approach enhances the uniformity and quality of electroplating at the wafer edge, improving yield, performance, and reliability of semiconductor devices, particularly in wafer level packaging (WLP) applications.
Implementation Method 1
electrochemically plating metal onto the wafer using the metal ions
Implementation Method 2
The plating may also include applying an anode current to an anode
Data Source
AI summary
Embodiments of the present technology may include an electroplating system. The electroplating system may include a vessel. The system may also include a wafer holder configured for holding a wafer in the vessel. The system may further include an anode in the vessel. In addition, the method may include a plurality of thief electrodes. For each thief electrode of the plurality of thief electrodes, a thief current channel may be defined by a channel wall. The channel wall for each thief electrode may define an aperture adjacent to the wafer holder. The thief current channel may extend from each thief electrode to the aperture. The system may include a current control system in electrical communication with the plurality of thief electrodes. The current control system may be configured such that an amount of current delivered to each thief electrode can be adjusted independently.