ESC Plasma Bias Mixing for Etching Direction Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The uniformity of plasma in substrate processing chambers affects etching performance, leading to defects such as misaligned etching directions and pattern defects due to the accumulation of positive ions on the substrate surface, which is caused by the application of negative voltage without positive voltage.
Innovation Solution
A plasma control apparatus using a RF power source, a non-sinusoidal wave power source, and a DC power source to apply both negative and positive voltages to the substrate, reducing interference through a mixer that synthesizes these signals and applies them to the lower electrode inside the electrostatic chuck.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only negative voltage is applied to the substrate, then plasma generation is achieved, but positive ions accumulate on the substrate surface causing etching direction misalignment and pattern defects
Solution Approach 1:
The patent applies positive voltage pulses before or during the negative voltage application to preemptively neutralize positive ion accumulation on the substrate surface. This preliminary anti-action prevents the harmful effect of ion accumulation before it can cause etching direction misalignment, while maintaining the plasma generation benefits of negative voltage.
Solution Approach 2:
The patent employs periodic switching between positive and negative voltage applications in a controlled sequence. The positive voltage phase neutralizes accumulated positive ions, while the negative voltage phase maintains plasma generation. This periodic action prevents ion accumulation defects while ensuring stable plasma processing.
2Manufacturing precision
If multiple power sources (RF, non-sinusoidal wave, DC) are used together, then both positive and negative voltages can be applied to reduce defects, but device complexity increases
Solution Approach 1:
The patent divides the voltage control function into three separate power sources, each responsible for a specific function: RF power source for plasma generation, non-sinusoidal wave power source for positive voltage pulses, and DC power source for bias control. This segmentation allows independent optimization of each power source while achieving the combined effect of defect reduction.
Solution Approach 2:
The patent designs the power source system where each component serves multiple purposes: the RF power source generates plasma while the non-sinusoidal wave source provides both positive voltage pulses and waveform control. This multi-functionality reduces the need for additional dedicated components, managing system complexity while achieving precise voltage control for defect reduction.
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 reduces process defects by neutralizing the polarity on the substrate surface, preventing positive ion accumulation and misalignment, thereby improving etching precision and reducing sharp defects.
Implementation Method 1
a first power source (111) configured to generate an RF signal
Implementation Method 2
a second power source (113) configured to generate a non-sinusoidal wave signal
Implementation Method 3
a third power source (115) configured to generate a DC signal
Implementation Method 4
a mixer (120) configured to generate an output signal based on the RF signal, the non-sinusoidal wave signal, and the DC signal, and provide the output signal to a lower electrode (220)
Implementation Method 5
provide the output signal to a lower electrode (220) inside an electrostatic chuck (ESC)
Data Source
AI summary
A plasma control apparatus may include a first power source configured to generate an RF signal, a second power source configured to generate a non-sinusoidal wave signal, a third power source configured to generate a direct current signal, and a mixer configured to generate an output signal based on the RF signal, the non-sinusoidal wave signal, and the DC signal, and provide the output signal to a lower electrode inside an electrostatic chuck (ESC) of a processing chamber.