Plasma Potential Adjustment Circuit for Narrow Ion Energy Control
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Solution Overview
Problem
Conventional plasma systems struggle to deliver ions to a substrate with a narrow ion energy distribution (IED) and ion angle distribution (IAD), leading to undesirable broadening of the IED, which affects process uniformity, repeatability, and yield in plasma processes such as etching.
Innovation Solution
A plasma system with a potential adjustment circuit that adjusts the sheath potential by monitoring and shaping the electric potential profile using pulsed power and sensors, allowing for precise control over the IED and IAD through a controller and passive elements like capacitors, inductors, and resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional power application methods are used, then plasma processes can be performed, but the ion energy distribution becomes undesirably broad
Solution Approach 1:
The patent applies periodic pulsed power to the plasma electrode and substrate, creating time-varying electric fields that control ion acceleration. By pulsing the power in synchronized cycles, the system achieves narrow ion energy distribution while maintaining process control through temporal modulation of the electric fields.
Solution Approach 2:
The patent incorporates sensors to measure electric potential and ion characteristics, feeding this information back to the controller. The controller adjusts the pulsed power parameters based on measured deviations, enabling closed-loop control that narrows the ion energy distribution while compensating for system variations.
2Manufacturing precision
If pulsed power is applied to control ion energy, then ion energy distribution narrows, but the system requires complex potential adjustment
Solution Approach 1:
The patent introduces a potential adjustment circuit as an intermediary component between the power supply and plasma electrode. This circuit actively shapes the electric potential profile to achieve the desired ion energy distribution, serving as a mediator that translates power input into precise ion energy control without requiring direct complex modifications to the power supply itself.
Solution Approach 2:
The patent dynamically adjusts multiple parameters including pulse duration, pulse frequency, duty cycle, and power amplitude to optimize ion energy distribution. By changing these parameters in coordinated fashion, the system achieves precise ion energy control while managing the complexity of the potential adjustment through systematic parameter optimization.
3Manufacturing precision
If sheath potential is not properly controlled, then plasma processes proceed, but etching uniformity deteriorates due to broad IED
Solution Approach 1:
The patent uses periodic pulsed power to create time-varying sheath potential that accelerates ions in a controlled manner during each pulse cycle. This periodic modulation ensures that ions gain energy uniformly during the acceleration phase, improving etching uniformity across the substrate while the pulsing nature simplifies the control of sheath potential compared to continuous DC operation.
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 system achieves a substantially flat sheath potential during ion charging phases, resulting in a narrower IED and improved etching performance, reducing bowing and aspect ratio-dependent etching issues.
Implementation Method 1
Electrical power may be pulsed to various structures to generate plasma and/or to influence plasma species in desirable ways for the furtherance of a given plasma process
Implementation Method 2
Bias power is often applied to structures electrically coupled to a substrate in order to direct charges species (such as positive ions) towards to substrate to process the substrate
Implementation Method 3
adjusting the electric potential profile at the plasma electrode based on the time-resolved electric potential information. Adjusting the electric potential profile adjusts the sheath potential of the plasma at the substrate
Data Source
AI summary
A method of adjusting sheath potential of a plasma at a substrate includes applying pulsed plasma source power to a plasma electrode in contact with the plasma while applying pulsed bias power to the substrate, measuring electric potential produced by the pulsed plasma source power and the pulsed bias power to obtain time-resolved electric potential information, and adjusting the electric potential profile at the plasma electrode based on the time-resolved electric potential information. Adjusting the electric potential profile adjusts the sheath potential of the plasma at the substrate. The method may be performed using a plasma system including the plasma electrode and a potential adjustment circuit coupled between the plasma electrode and at least one pulsed DC power supply. The potential adjustment circuit may be configured to adjust the electric potential profile at the plasma electrode.