Ion Beam Shaping with Quadrupole Electromagnets
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Solution Overview
Problem
In ion implantation systems, achieving uniform ion implantation requires shaping the beam into an elliptical or oval section elongated in the lateral direction, which is challenging due to beam divergence and cutting issues, especially when the distance between the mass analysis magnet and deflection scanner varies.
Innovation Solution
The solution involves installing a mass analysis slit between the mass analysis magnet and deflection scanner, with first and second DC quadrupole electromagnets on either side to converge and diverge the beam in specific directions, ensuring the beam enters the deflection scanner with an elliptical or oval shape, minimizing longitudinal divergence and preventing unnecessary cutting and divergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the beam is shaped into an elliptical or oval section elongated in the lateral direction to ensure uniform ion implantation, then the uniformity of ion implantation is improved, but the beam undergoes divergence and cutting issues that worsen beam quality and intensity
Solution Approach 1:
The beam is pre-shaped into an elliptical or oval cross-section before entering the deflection scanner, and the longitudinal position of the beam waist is predetermined and adjusted. This preliminary shaping and positioning prevents subsequent beam divergence and cutting issues during the scanning process, ensuring uniform ion implantation across the substrate surface.
Solution Approach 2:
The invention adjusts the longitudinal position of the beam waist as a key parameter to optimize beam propagation characteristics. By changing the position of the beam waist relative to the deflection scanner, the beam maintains its shaped cross-section without excessive divergence or cutting, thereby maintaining both uniformity and beam quality throughout the scanning process.
2Area of stationary object
If the distance between the mass analysis magnet and deflection scanner is increased to accommodate larger substrates, then the processing area is expanded, but the beam divergence and cutting problems worsen
Solution Approach 1:
The beam is pre-shaped and its waist position is predetermined before the beam enters the deflection scanner. This preliminary configuration ensures that the beam maintains optimal propagation characteristics over extended distances, allowing larger substrate areas to be processed without suffering from beam divergence or cutting problems that would normally worsen with increased distance.
Solution Approach 2:
By adjusting the longitudinal position of the beam waist as a controllable parameter, the system optimizes beam propagation for extended distances between the mass analysis magnet and deflection scanner. This parameter adjustment allows the beam to maintain its shaped cross-section and intensity distribution even when processing larger substrate areas requiring greater separation between components.
3Manufacturing precision
If the beam cross-section is reduced in the longitudinal direction to prevent cutting, then beam uniformity is improved, but the beam intensity and coverage area are reduced
Solution Approach 1:
The beam is pre-shaped into an elliptical or oval cross-section with the major axis in the lateral direction before entering the deflection scanner. This preliminary shaping allows the beam to maintain uniformity without excessive reduction in the longitudinal dimension, as the predetermined beam waist position ensures optimal propagation characteristics that prevent cutting while preserving beam intensity and coverage area.
Solution Approach 2:
By adjusting the longitudinal position of the beam waist, the system optimizes the balance between beam uniformity and beam intensity. This parameter control allows the beam to maintain sufficient intensity and coverage area while achieving the necessary uniformity for precise ion implantation, avoiding excessive beam reduction that would compromise quantity.
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 allows for precise beam shaping, maintaining uniformity at irradiation positions and enabling increased low-energy beam usage by minimizing longitudinal-direction divergence and preventing beam cutting, even with varying distances between system components.
Implementation Method 1
ions produced in an ion source 301 are extracted as a beam 302 through a non-illustrated extraction electrode. The extracted beam 302 is subjected to a mass analysis in a mass analysis magnet device 303 so that a necessary ion species is selected.
Implementation Method 2
The beam 302 composed of the necessary ion species is shaped in cross section by a beam shaper 304. The beam having the shaped cross section is deflected by a deflection scanner 305
Implementation Method 3
A first DC quadrupole electromagnet and a second DC quadrupole electromagnet are installed on an upstream side and a downstream side of the mass analysis slit, respectively... causing the ion beam to converge in the longitudinal direction and to diverge in the lateral direction
Implementation Method 4
The beam having the shaped cross section is deflected by a deflection scanner 305 in a direction parallel to the sheet surface of FIG. 1A... The selected ion species is deflected slightly downward in the angular energy filter 308
Data Source
AI summary
A beam processing system is for causing a particle beam extracted from a beam generating source to pass through a mass analysis magnet device, a mass analysis slit, and a deflection scanner in the order named, thereby irradiating the particle beam onto a processing object. The mass analysis slit is installed between the mass analysis magnet device and the deflection scanner at a position where the particle beam having passed through the mass analysis magnet device converges most in a lateral direction. A first DC quadrupole electromagnet and a second DC quadrupole electromagnet are installed on an upstream side and a downstream side of the mass analysis slit, respectively.