Axial Ion Beam Extraction via Diffusion Chamber and Multicusp Field
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ion implantation processes face challenges in achieving a wide and uniform ribbon ion beam due to the radially non-uniform plasma density profiles produced by ICP and ECR plasma sources, which limits their application in large area processing.
Innovation Solution
An ion source design incorporating one or two ICP or ECR plasma sources paired with a diffusion chamber and a multicusp magnetic field to create a uniform plasma density along the axial direction, ensuring a uniform extracted ribbon ion beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ICP or ECR plasma sources are used to generate ion beams, then high plasma density and ionization efficiency are achieved, but the radially non-uniform plasma density profile limits the beam uniformity and applicability to large area processing
Solution Approach 1:
The patent transitions from extracting ions radially (perpendicular to the plasma column axis) to extracting ions axially (parallel to the plasma column axis). This dimensional change in extraction geometry allows the use of a slit aperture oriented along the plasma column, capturing ions from a larger volume while maintaining uniformity across the beam width, thus resolving the contradiction between high plasma density and beam uniformity for large area processing
2Area of stationary object
If the extraction aperture area is increased to widen the ion beam, then large area processing capability is improved, but the beam uniformity deteriorates due to the radially non-uniform plasma density profile
Solution Approach 1:
By orienting the slit aperture axially along the plasma column rather than radially perpendicular to it, the patent enables the extraction aperture to span a large area while maintaining beam uniformity. The axial orientation allows the slit to sample plasma density more uniformly along the plasma column length, overcoming the radial non-uniformity that would otherwise limit uniformity when increasing aperture area
Solution Approach 2:
The patent uses a slit aperture that effectively copies or samples the plasma density distribution along the axial direction, where the density is more uniform, rather than sampling the radially non-uniform distribution. This copying approach from a more uniform region of the plasma enables large area extraction with maintained uniformity
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 enables the generation of high-current, uniformly distributed ribbon ion beams over extended widths, improving the uniformity and effectiveness of ion implantation processes, particularly for large diameter wafers and solar cell doping.
Implementation Method 1
power supply 1 delivers the required energy (DC or RF) to the plasma source 2 to enable ionization of the doping gas
Implementation Method 2
An ion source design incorporating one or two ICP or ECR plasma sources
Implementation Method 3
A beam of positive ions is extracted from the source, accelerated to the desired energy
Implementation Method 4
A commonly used scheme is a triode combination in which the plasma chamber aperture is at high positive potential, then a second electrode (suppression electrode) at negative potential and finally a third electrode at ground potential
Implementation Method 5
The extracted ion beam is composed of a mixture of ions. For instance, the beam extracted from BF3 gas will be comprised mainly of BF3+, BF2+, BF+, B+, and F+ ions. Therefore, it is necessary to use the mass analyzer to remove unwanted components from the ion beam
Implementation Method 6
To reduce the energy to the desired level, ions of the desired species then pass through a deceleration stage 8, which may include one or more electrodes
Implementation Method 7
A corrector magnet 10 is used to expand the ion beam and then transform it into a parallel ribbon ion beam
Implementation Method 8
An ion source design incorporating one or two ICP or ECR plasma sources paired with a diffusion chamber and a multicusp magnetic field to create a uniform plasma density along the axial direction
Implementation Method 9
a diffusion chamber and a multicusp magnetic field to create a uniform plasma density along the axial direction, ensuring a uniform extracted ribbon ion beam
Data Source
AI summary
An ion source, capable of generating high-density wide ribbon ion beam, utilizing one or more plasma sources is disclosed. In addition to the plasma source(s), the ion source also includes a diffusion chamber. The diffusion chamber has an extraction aperture oriented along the same axis as the dielectric cylinder of the plasma source. In one embodiment, dual plasma sources, located on opposing ends of the diffusion chamber are used to create a more uniform extracted ion beam. In a further embodiment, a multicusp magnetic field is used to further improve the uniformity of the extracted ion beam.