Dynamic Plating Uniformity via Secondary Electrode Current Control
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Solution Overview
Problem
Current electroplating technologies face challenges in achieving uniformity, particularly radial and azimuthal non-uniformity, when processing semiconductor wafers with varying seed layer resistivities and feature distributions, leading to inefficiencies and downtime due to the need for hardware changes to accommodate different substrates.
Innovation Solution
An electroplating apparatus with a plating chamber separated into anolyte and catholyte compartments by an ion-permeable membrane, featuring a secondary electrode and an ionically resistive ionically permeable element that allows for dynamic control of plating current distribution without crossing the membrane, enabling uniform plating on dissimilar substrates without mechanical changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single primary anode is used in conventional electroplating, then the apparatus structure is simple, but radial non-uniformity occurs due to edge-to-center voltage drop in resistive seed layers
Solution Approach 1:
The single primary anode is segmented into multiple independently controllable anodes (first anode, second anode, third anode) positioned at different radial locations. This allows independent control of current density at different zones, compensating for the voltage drop in resistive seed layers and achieving uniform plating without increasing overall apparatus complexity.
Solution Approach 2:
Different anodes are assigned to different radial zones with tailored current densities. The first anode serves the inner region, the second anode serves the middle region, and the third anode serves the outer region. This local quality approach ensures each zone receives appropriate current density to maintain plating uniformity across the entire substrate.
2Manufacturing precision
If hardware changes are made to accommodate different substrates, then plating uniformity can be optimized for specific substrates, but downtime increases
Solution Approach 1:
The system uses dynamically controllable current densities for each anode rather than fixed hardware configurations. The controller can adjust current density distribution in real-time to match different substrate types, resistivities, and feature densities, eliminating the need for hardware changes and reducing downtime between different substrate batches.
Solution Approach 2:
Instead of changing hardware, the invention changes operational parameters (current density, voltage distribution) to adapt to different substrates. The controller modifies electrical parameters to optimize plating uniformity for various substrate configurations, maintaining precision without mechanical intervention.
3Ease of operation
If current density is uniformly distributed, then the apparatus is easy to control, but azimuthal non-uniformity occurs due to varying feature densities at different angular positions
Solution Approach 1:
The anodes are segmented into azimuthal zones (inner, middle, outer regions with different angular spans) that can be independently controlled. Each zone's current density is adjusted according to the local feature density and plating requirements, enabling precise azimuthal uniformity control while maintaining relatively simple overall system operation through the controller.
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 solution significantly reduces downtime and improves plating uniformity by dynamically controlling the plating current, ensuring consistent metal deposition across varying substrate features, enhancing the efficiency and adaptability of the electroplating process.
Implementation Method 1
a plating chamber configured to contain an electrolyte, the plating chamber comprising a catholyte compartment and an anolyte compartment, wherein the anolyte compartment and the catholyte compartment are separated by an ion-permeable membrane
Implementation Method 2
an ionically resistive ionically permeable element positioned between the ion-permeable membrane and the substrate holder, wherein the ionically resistive ionically permeable element is adapted to provide ionic transport through the element during electroplating
Implementation Method 3
a secondary electrode configured to donate and/or divert plating current (also referred to here as ionic current) to and/or from the general periphery of the substrate, wherein the secondary electrode is positioned such that the donated and/or diverted plating current does not cross the ion-permeable membrane
Implementation Method 4
electroplating a metal on the substrate while controlling plating non-uniformity
Implementation Method 5
Electrochemical deposition is now poised to fill a commercial need for sophisticated packaging and multichip interconnection technologies
Data Source
AI summary
An apparatus for electroplating metal on a substrate while controlling plating uniformity includes in one aspect: a plating chamber having anolyte and catholyte compartments separated by a membrane; a primary anode positioned in the anolyte compartment; an ionically resistive ionically permeable element positioned between the membrane and a substrate in the catholyte compartment; and a secondary electrode configured to donate and/or divert plating current to and/or from the substrate, wherein the secondary electrode is positioned such that the donated and/or diverted plating current does not cross the membrane separating the anolyte and catholyte compartments, but passes through the ionically resistive ionically permeable element. In some embodiments the secondary electrode is an azimuthally symmetrical anode (e.g., a ring positioned in a separate compartment around the periphery of the plating chamber) that can be dynamically controlled during electroplating.