Electron Bias Waveforms for Precise DC Plasma Surface Processing
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Solution Overview
Problem
Existing DC plasma processing systems face challenges in precisely controlling the kinetic energy of free electrons to target specific energy levels of atoms at the substrate surface, due to uncertainties in the surface floating potential and variations in operating conditions.
Innovation Solution
The system employs a method to precisely control the surface floating potential of the substrate, allowing for the generation of wafer-scale waves of electrons with controlled kinetic energy. This is achieved by using a DC plasma system with a biasing signal generator that produces waveforms tailored to match the energy levels of the substrate atoms, ensuring precise and selective energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If externally applied bias signal is used to accelerate electrons towards substrate, then material processing can be performed, but the kinetic energy of electrons cannot be precisely controlled to target specific energy levels of substrate atoms due to uncertainties in surface floating potential
Solution Approach 1:
The system measures the actual surface floating potential of the substrate and uses this measurement as feedback to adjust the bias signal waveform. The bias signal generator creates waveforms with timing and amplitude specifically tailored to compensate for the measured floating potential, ensuring that electrons achieve the desired kinetic energy levels that precisely target atomic energy levels in the substrate material.
Solution Approach 2:
The invention dynamically adjusts the parameters of the bias signal waveform (timing, amplitude, shape) based on the measured surface floating potential. By changing these parameters to match the actual operating conditions, the system ensures that electrons are accelerated to the correct kinetic energy levels despite variations in substrate potential, enabling precise targeting of specific atomic energy levels.
2Manufacturing precision
If conventional DC plasma processing is used, then material processing can be performed, but electron energy levels do not precisely match the energy thresholds of target atoms due to floating potential variations
Solution Approach 1:
The system incorporates measurement of the surface floating potential and uses this information to generate customized bias waveforms. This feedback mechanism allows the system to automatically adjust the electron energy levels to precisely match the energy thresholds of target atoms in the substrate, achieving high manufacturing precision without requiring complex manual calibration procedures.
Solution Approach 2:
The system performs self-adjustment by measuring its own operating conditions (surface floating potential) and automatically generating the appropriate bias signal waveform. This self-service capability eliminates the need for external complex control systems while achieving precise energy level matching, thereby managing device complexity through automated self-regulation.
3Object-affected harmful factors
If electrons are used for substrate processing instead of ions, then damage to substrate surface can be reduced, but precise control of electron kinetic energy to target specific atomic energy levels becomes more difficult
Solution Approach 1:
The system dynamically changes the parameters of the bias signal waveform based on measured surface floating potential to precisely control electron kinetic energy. This allows electrons to be accelerated to specific energy levels that exactly match atomic energy thresholds in the substrate, achieving high manufacturing precision while maintaining the low-damage advantage of electron-based processing.
Solution Approach 2:
By measuring the surface floating potential and using this feedback to adjust electron acceleration, the system ensures that electrons reach the precise kinetic energy levels needed for damage-free processing. The feedback control guarantees that electrons target specific atomic energy levels without excessive energy that would cause substrate damage.
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 enables precise control of the kinetic energy of free electrons, allowing for exact and selective targeting of energy levels at the substrate surface, thereby enhancing the precision and effectiveness of material processing while minimizing damage.
Implementation Method 1
generating a DC plasma; producing a floating potential at a surface of the substrate support stage
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
Systems and methods for material processing using wafer scale waves of precisely controlled electrons in a DC plasma is presented. A surface floating potential of a substrate placed atop a stage in a positive column of the DC plasma is adjusted and maintained to a reference potential. A periodic biasing signal referenced to the reference potential is capacitively coupled to the stage to control a surface potential at the substrate according to: an active phase for provision of kinetic energy to free electrons in the DC plasma for activation of targeted bonds at the surface of the substrate; a neutralization phase for repelling of the free electrons from the surface of the substrate; and an initialization phase for restoring an initial condition of the surface floating potential.