Inductively Coupled Plasma Antenna Segmentation for Uniform Density
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Solution Overview
Problem
Conventional inductively coupled plasma processing apparatuses face challenges in achieving uniform plasma density on substrates due to significant RF power loss within the high frequency power supply unit, leading to decreased plasma generation efficiency and increased complexity in the matching unit.
Innovation Solution
The apparatus employs multiple secondary coils connected to a primary coil via electromagnetic induction, forming closed-loop secondary circuits with capacitors to control plasma density distribution and reduce RF power loss by varying electrostatic capacitances, thereby enhancing plasma generation efficiency and simplifying the matching unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional RF antenna is used in an inductively coupled plasma processing apparatus, then the apparatus structure is simple, but the plasma density uniformity on the substrate is insufficient
Solution Approach 1:
The RF antenna is divided into multiple coil-shaped antenna segments arranged in a specific pattern. Each segment independently generates RF magnetic fields that collectively produce uniform plasma density distribution across the substrate surface, resolving the contradiction between simplicity and uniformity.
Solution Approach 2:
Different antenna segments are positioned at specific locations to create localized plasma generation zones. By strategically placing segments and controlling their individual RF power, the system achieves uniform overall plasma density while maintaining relatively simple segment structures.
2Manufacturing precision
If multiple antenna segments with impedance control circuits are used to control plasma density distribution, then plasma uniformity is improved, but the device complexity and RF power loss increase
Solution Approach 1:
The multiple antenna segments serve dual functions: they individually control plasma density in specific regions while collectively acting as a unified antenna system. This multi-functionality reduces the need for complex independent impedance control circuits for each segment, simplifying the overall matching unit.
Solution Approach 2:
The impedance control functions of multiple antenna segments are merged into a single centralized matching unit. This unified approach controls the RF power distribution to all segments simultaneously, reducing device complexity compared to having separate impedance control circuits for each segment.
3Productivity
If conventional RF power distribution is used in the high frequency power supply unit, then the system is simple, but significant RF power loss occurs leading to decreased plasma generation efficiency
Solution Approach 1:
The system dynamically adjusts RF power distribution to multiple antenna segments based on real-time plasma conditions and substrate requirements. This dynamic power optimization ensures maximum plasma generation efficiency while minimizing RF power loss in the high frequency power supply unit, achieving better productivity without excessive 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
This configuration results in improved plasma uniformity and increased RF power transmission efficiency, reducing power loss and simplifying the matching unit, leading to enhanced plasma generation and process uniformity.
Implementation Method 1
multiple secondary coils, each being coupled with the primary coil by electromagnetic induction
Implementation Method 2
A RF magnetic field is generated around a RF antenna by a RF current flowing through the RF antenna. Magnetic force lines of the RF magnetic field penetrate the dielectric window, and pass through the processing space within the chamber. As the RF magnetic field changes with time, an inductive electric field is generated in an azimuth direction within the processing space. Then, electrons accelerated by this inductive electromagnetic field in the azimuth direction collide with molecules or atoms of the processing gas so as to be ionized.
Data Source
AI summary
There is provided an inductively coupled plasma processing apparatus capable of reducing a RF power loss within a high frequency power supply unit (particularly, a matching unit) and capable of enhancing a plasma generation efficiency. In this inductively coupled plasma processing apparatus, a multiple number of closed-loop secondary circuits 96, 98 independent from each other are formed between a coaxial antenna group 54 and a transformer 68. Further, by varying electrostatic capacitances of variable capacitors 64 and 66, secondary currents I2A and I2B flowing through an inner antenna 58 and an outer antenna 60, respectively, of the coaxial antenna group 54 are independently controlled. Accordingly, it is possible to readily control a plasma density distribution on a semiconductor wafer W in a diametrical direction.