Electroplating Current Ramping for Uniform Seed Layer Deposition
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving uniform metal deposition on substrates with thin, resistive seed layers during electroplating, particularly due to non-uniform current density distribution and seed layer corrosion, leading to defects and voids in features like trenches and vias.
Innovation Solution
Dynamic control of the current profile during substrate immersion, accounting for the changing surface area in contact with the electrolyte, using techniques such as current ramping and pulsing to maintain a constant current density and protect the seed layer, thereby ensuring uniform film growth and reduced defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If constant current is applied during substrate immersion, then the immersion process is simple to control, but non-uniform current density distribution occurs on the substrate surface
Solution Approach 1:
The patent applies dynamic current control during substrate immersion, where the current magnitude is continuously adjusted based on the immersed surface area. As the substrate enters the electrolyte, the current is ramped up from zero to a target value over a predetermined time period, ensuring uniform current density distribution across the progressively immersed surface while maintaining simple automated control through programmable power supply.
2Productivity
If high current density is applied to achieve rapid metal deposition, then productivity increases, but seed layer corrosion and defect formation increase
Solution Approach 1:
The patent applies preliminary cathodic polarization to the seed layer before metal deposition begins. A cathodic current is applied during the immersion and nucleation phase to protect the thin seed layer from corrosion and promote uniform metal nucleation. This preliminary action strengthens the seed layer and establishes uniform current distribution before high-current deposition starts, preventing defects and voids while maintaining high productivity during the subsequent deposition phase.
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 results in smoother, more uniform metal depositions with fewer defects, improved seed layer protection, and reduced void formation, enhancing the quality of plated films and reducing defects introduced during chemical mechanical polishing.
Implementation Method 1
various aspects disclosed herein relate to methods of controlling the current profile and thereby controlling the metal deposition on substrates as they enter electroplating solutions
Data Source
AI summary
In some method and apparatus disclosed herein, the profile of current delivered to the substrate provides a relatively uniform current density on the substrate surface during immersion. These methods include controlling the current density applied across a substrate's surface during immersion by dynamically controlling the current to account for the changing substrate surface area in contact with electrolyte during immersion. In some cases, current density pulses and/or steps are used during immersion, as well.