High Resistance Virtual Anode for Uniform Electroplating
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Solution Overview
Problem
Conventional electroplating processes suffer from nonuniformity in the deposition of electrically conductive layers on semiconductor wafers due to the 'edge effect', where the layer tends to be thicker near the wafer edge than at the center, leading to variations in device characteristics.
Innovation Solution
A high resistance virtual anode (HRVA) is introduced, comprising a first and second layer with adjustable through holes, forming a pepper pot-like structure to modify electric current flux and plating solution flow, ensuring uniform thickness of the deposited layer across the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electroplating process is used, then the electroplating process is simple and easy to operate, but the deposited electrically conductive layer is nonuniform with thickness variation due to edge effect
Solution Approach 1:
The virtual anode is segmented into multiple regions with different hole size distributions. The anode structure is divided into a first region with larger holes and a second region with smaller holes, creating localized current density variations that compensate for the edge effect and achieve uniform plating thickness across the wafer surface.
Solution Approach 2:
Different regions of the virtual anode are assigned different local properties (hole sizes) to address specific local requirements. The first region with larger holes serves areas requiring higher current density, while the second region with smaller holes serves areas requiring lower current density, thereby achieving uniform deposition thickness.
2Adaptability or versatility
If virtual anode with fixed hole structure is used, then the device complexity is low, but the adaptability to different wafer sizes and plating requirements is limited
Solution Approach 1:
The virtual anode structure is made dynamically adjustable by incorporating movable members that can reposition the first and second regions. This allows the hole size distribution to be dynamically changed to match different wafer sizes and plating requirements, enhancing adaptability while maintaining a relatively simple base structure.
Solution Approach 2:
The virtual anode is designed with multi-functionality to handle various wafer sizes (e.g., 300mm, 450mm) and different plating requirements through a single adjustable structure. The movable members enable the same anode to be reconfigured for different applications, eliminating the need for multiple specialized anodes.
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 HRVA effectively addresses the edge effect by achieving uniformity in the electrically conductive layer thickness, reducing variations to 2.5% for larger wafers like 450 mm, compared to the 10% uniformity achieved with commercial systems.
Implementation Method 1
The HRVA includes a first layer and a second layer... the first layer includes a plurality of first holes through the first layer, and the second layer includes a plurality of second holes through the second layer... effectively addresses the edge effect by achieving uniformity in the electrically conductive layer thickness
Implementation Method 2
Electroplating involves making electrical contact with the wafer surface upon which the electrically conductive layer is to be deposited... Current is then passed through a plating solution... between an anode and the wafer plating surface... This causes an electrochemical reaction on the wafer plating surface which results in the deposition of the electrically conductive layer
Implementation Method 3
a solution containing ions of the element being deposited, for example a solution containing Cu2+
Data Source
AI summary
A high resistance virtual anode for an electroplating cell includes a first layer and a second layer. The first layer includes a plurality of first holes through the first layer. The second layer is over the first layer and includes a plurality of second holes through the second layer.