Plasma Processing Apparatus Movable Feed Conductor
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Solution Overview
Problem
Capacitively coupled plasma processing apparatuses face challenges in achieving uniform plasma density distribution, particularly with increasing substrate sizes and high-frequency power applications, leading to non-uniform processing and reduced manufacturing yield due to standing waves and skin effects.
Innovation Solution
The apparatus features a dual-frequency RF power supply system with a movable feed conductor that adjusts capacitance and impedance between central and peripheral electrodes, allowing for flexible control of plasma density distribution by varying the position of the movable feed conductor, enabling arbitrary control of RF power distribution and improving uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high frequency power is applied to generate plasma, then plasma generation efficiency is improved, but plasma density uniformity deteriorates due to standing waves and skin effects
Solution Approach 1:
The lower electrode is divided into a central electrode and an annular electrode, allowing independent RF power application to each region. This segmentation enables different frequency powers to be applied to different zones, improving overall plasma uniformity while maintaining high generation efficiency
Solution Approach 2:
Different regions of the electrode structure are assigned different functions: the central electrode receives high frequency power for efficient plasma generation, while the annular electrode receives low frequency power for uniform plasma distribution. This local differentiation resolves the contradiction between efficiency and uniformity
2Manufacturing precision
If dielectric member is embedded in electrode to improve plasma density uniformity, then plasma density uniformity is improved, but process flexibility deteriorates
Solution Approach 1:
The movable feed conductor allows dynamic adjustment of the plasma density profile by changing its position. This enables the system to adapt to different process requirements and substrate sizes, maintaining both uniformity and flexibility that the fixed dielectric embedding cannot provide
3Area of stationary object
If chamber size is increased to accommodate larger substrates, then substrate processing capability is improved, but plasma density uniformity deteriorates
Solution Approach 1:
The electrode is segmented into central and annular regions that can be independently controlled. This allows the plasma source to be distributed across the larger chamber area, maintaining uniform plasma density even as the processing area increases
Solution Approach 2:
By independently adjusting the RF power parameters applied to the central and annular electrodes, the plasma density distribution can be optimized for different chamber sizes and substrate areas, maintaining uniformity across varying processing scales
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 ensures uniform plasma density distribution across the substrate, enhancing processing uniformity and yield by optimizing the ratio of RF power supplied to central and peripheral electrodes, while maintaining compatibility with conventional systems.
Implementation Method 1
a movable feed conductor which is movable within a specific range and electrically connects the central feed conductor and the circumferential feed conductor with respect to the first RF power supplied from the first RF power supply by capacitance coupling
Implementation Method 2
By applying a high frequency power (an RF power) to both electrodes, electrons accelerated by a high frequency electric field formed between the electrodes, secondary electrons emitted from the electrodes, or heated electrons collide with molecules of a processing gas to generate ions. Accordingly, a plasma of the processing gas is generated
Implementation Method 3
a second RF power preferably having a relatively low frequency (generally lower than or equal to about 13.56 MHz) for ion attraction to the substrate (bias) are simultaneously applied to a lower electrode
Data Source
AI summary
A plasma processing apparatus includes a processing chamber; a lower center electrode mounting thereon a target substrate; a lower peripheral electrode; an upper electrode disposed above the lower center electrode; a gas supplying unit supplying a processing gas into the processing chamber; a first RF power supply outputting a first RF power for generating a plasma of the processing gas; a second RF power supply for outputting a second RF power for introducing ions into the substrate; and a central feed conductor connected to a rear surface of the lower center electrode. The apparatus further includes a circumferential feed conductor connected to a rear surface of the lower peripheral electrode to bypass and supply some of the first RF power to the lower peripheral electrode; and a movable feed conductor electrically connecting the central feed conductor and the circumferential feed conductor for the first RF power by capacitance coupling.