Plating Cup Contoured Bottom for Uniform Electroplating
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Solution Overview
Problem
Thinner seed layers in electroplating for integrated circuits exhibit higher resistance, leading to uneven voltage distribution and defects in plated layers, particularly in notch areas of substrates, due to longer current paths and lower conductivity.
Innovation Solution
The introduction of clamshells with protrusions and insulated portions in notch areas to modify current distribution, using protrusions that can be up to 1000 micrometers high and made from insulating materials, and longer contact fingers to ensure uniform electroplating across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thinner seed layers are used in electroplating, then manufacturing precision is improved, but electrical conductivity deteriorates leading to uneven voltage distribution
Solution Approach 1:
The cup bottom is designed with spatially varying conductivity: highly conductive regions in notch areas and less conductive regions in non-notch areas. This local differentiation compensates for the thinner seed layer conductivity by providing preferential current paths in critical areas, enabling uniform electroplating across the entire substrate surface.
Solution Approach 2:
The electrical conductivity parameter of the cup bottom is varied across different spatial regions. By making the cup bottom more conductive in notch areas compared to non-notch areas, the patent modifies the current distribution parameters to compensate for the thinner seed layer, achieving uniform voltage distribution and consistent plating thickness.
2Device complexity
If standard contact fingers are used, then device complexity is minimized, but manufacturing precision deteriorates due to uneven plating thickness
Solution Approach 1:
Contact fingers are differentiated by length based on their spatial position: longer contact fingers are positioned in notch areas while shorter contact fingers are used in non-notch areas. This local variation compensates for the thinner seed layer conductivity in notch regions, ensuring uniform current distribution and consistent plating thickness across the substrate.
3Manufacturing precision
If protrusions are added to the cup bottom, then manufacturing precision is improved for uniform electroplating, but device complexity increases
Solution Approach 1:
The cup bottom incorporates protrusions only in specific notch areas rather than uniformly across the entire surface. This localized structural modification provides the necessary current distribution control in critical regions while maintaining a simpler overall cup bottom design, balancing manufacturing precision improvement with device complexity control.
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 configuration compensates for reduced deposition rates in notch areas by altering current distribution, resulting in more uniform electroplating and reduced edge defects, maintaining consistent thickness profiles across the substrate.
Implementation Method 1
an elastomeric seal disposed on the cup and configured to engage the wafer during electroplating, where upon engagement the elastomeric seal substantially excludes plating solution from a peripheral region of the wafer
Implementation Method 2
one or more contact elements for supplying electrical current to the wafer during electroplating
Implementation Method 3
electroplating is a common technique used in integrated circuit (IC) fabrication to deposit one or more layers of conductive metal
Implementation Method 4
drive an electrical current through the electroplating cell and deposit metal onto the substrate surface from metal ions available in the electrolyte
Data Source
AI summary
Disclosed herein are cups for engaging wafers during electroplating in clamshell assemblies and supplying electrical current to the wafers during electroplating. The cup can comprise an elastomeric seal disposed on the cup and configured to engage the wafer during electroplating, where upon engagement the elastomeric seal substantially excludes plating solution from a peripheral region of the wafer, and where the elastomeric seal and the cup are annular in shape, and comprise one or more contact elements for supplying electrical current to the wafer during electroplating, the one or more contact elements attached to and extending inwardly towards a center of the cup from a metal strip disposed over the elastomeric seal. A notch area of the cup can have a protrusion or an insulated portion on a portion of a bottom surface of the cup where the notch area is aligned with a notch in the wafer.