Capacitively Symmetric Inductive Plasma Source for Non-Uniformity
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Solution Overview
Problem
Inductive plasma sources with high RF currents generate parasitic capacitive currents, leading to plasma non-uniformity, electrical damages to wafers, and increased RF power losses, particularly in compact reactors where impedance matching and resonance requirements are challenging.
Innovation Solution
A capacitively and geometrically symmetric inductive plasma source with a grounded terminal at the central position, featuring a cylindrical or flat spiral coil configuration, which balances parasitic capacitive currents by generating equal phase and anti-phase capacitive potentials, reducing net capacitive current and RF power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high RF currents are used in inductive plasma sources, then plasma density is improved, but parasitic capacitive currents increase causing plasma non-uniformity and electrical damages
Solution Approach 1:
The inductor is segmented into two separate coils (first and second inductive coils) with independent RF power supplies. This segmentation allows independent control of each coil's RF power, enabling optimization of plasma density while managing parasitic capacitive currents by adjusting the power distribution to each segment.
Solution Approach 2:
The invention changes the operational parameters by providing independent RF power control to each inductive coil segment. This allows dynamic adjustment of the RF power parameters to each coil, optimizing the balance between achieving high plasma density and minimizing harmful capacitive effects on the substrate.
2Quantity of substance
If high RF currents are used in inductive plasma sources, then plasma density is improved, but plasma non-uniformity increases
Solution Approach 1:
Dividing the inductor into two separate coils allows independent control of plasma generation in different regions. This segmentation enables better spatial distribution of plasma density and improved uniformity across the processing chamber by adjusting each coil's contribution independently.
Solution Approach 2:
Independent RF power control of each coil segment allows optimization of plasma uniformity by adjusting the power parameters to achieve balanced plasma distribution while maintaining high overall plasma density.
3Use of energy by moving object
If resonance excitation is used in compact reactors, then RF power transfer is improved, but device complexity increases
Solution Approach 1:
The inductor is divided into two independently controlled coils, which provides flexibility in RF power distribution and reduces the stringent impedance matching requirements associated with resonance excitation in compact reactors. This segmentation allows more straightforward power coupling.
Solution Approach 2:
The invention introduces dynamic control capability through independent RF power supplies for each coil segment, allowing real-time adjustment of power distribution without relying on fixed resonance conditions, thereby simplifying the overall system complexity.
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 achieves balanced inductor-plasma capacitive interaction, minimizing electrical damages and plasma non-uniformity, allowing for stable plasma processing across a wide range of conditions without the need for resonance excitation, thus enhancing semiconductor processing and reducing operational complexity.
Implementation Method 1
at least one inductor for providing a radio frequency induction field
Implementation Method 2
capacitance to plasma caused by the inductor between one end terminal and the grounded terminal, and capacitance to plasma of the inductor between the grounded terminal and another end terminal are substantially same
Data Source
AI summary
The present invention discloses an apparatus for plasma processing comprising of a chamber for plasma processing with an external wall, and at least one induction coil for providing a radio frequency induction field that is adjacent to the chamber. It further includes an end terminal of the induction coil that is connected to a radio frequency power supply, another end terminal of the induction coil that is open-ended, and a grounded terminal of the induction coil that is located at substantially central position of the induction coil.