Plasma Source Body for Density Uniformity
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Solution Overview
Problem
Plasma sources often suffer from non-uniform plasma density distribution near chamber walls, leading to processing non-uniformity in work pieces, which is partially addressed by using magnetic fields but with undesirable effects.
Innovation Solution
Incorporating a body within the plasma chamber to absorb power and reduce plasma density gradients, making the plasma density more uniform across the chamber, which can be used alone or in combination with magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If magnetic fields are used to reduce electron loss to chamber walls, then plasma density uniformity is improved, but longitudinal magnetic field effects are produced that may not be desirable
Solution Approach 1:
The patent extracts the function of creating plasma uniformity from the magnetic field system and assigns it to a separate body inserted into the plasma chamber. This body, with specific geometric features, directly modifies plasma density distribution without requiring longitudinal magnetic fields, thereby separating the beneficial effect (uniformity) from the harmful effect (magnetic field interference).
Solution Approach 2:
The patent introduces a body as an intermediary element between the plasma source and the chamber walls. This body acts as a mediator that absorbs excess plasma density and controls electron-ion recombination, achieving uniform plasma distribution without relying on magnetic field interactions that produce unwanted longitudinal effects.
2Power
If ion sources are operated at very low input powers to create lower power beams, then beam power is reduced, but control problems arise
Solution Approach 1:
Instead of operating the ion source at very low power to achieve low beam power, the patent inverts the approach by operating the source at higher, more controllable power levels and then using a body within the chamber to absorb excess plasma density and reduce the beam power to the desired level. This maintains ease of operation while achieving the target beam power.
Solution Approach 2:
The patent introduces a body as an intermediary power reduction element. This body absorbs excess plasma and reduces ion beam power without requiring the entire source system to operate at difficult-to-control low power levels, thereby maintaining operational ease while achieving low beam power output.
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
Achieves improved plasma uniformity and control, allowing for consistent processing of work pieces and efficient operation of low-power ion sources by adjusting plasma density and ion flow.
Implementation Method 1
a body located in the plasma chamber for absorbing power from a plasma contained in the chamber
Implementation Method 2
a plasma generator having an input power of above about 100 W
Data Source
AI summary
This invention relates to a plasma source in the form of plasma generator (13) which utilizes an antenna (11) and an RF source (12). The generated plasma flows into a chamber (14) and ions are accelerated out of the chamber (14) by grid (15). A body 16 is located in the volume for creating local losses and thereby reducing local plasma density.