Graded Electrostatic Lens for Ion Beam Deflection Control
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Solution Overview
Problem
Conventional ion implantation technologies face challenges in independently controlling the deflection and focus of an ion beam in deceleration and deflecting lenses, leading to difficulties in tuning the ion beam's size and position due to the dependence of voltage on beam energy and current.
Innovation Solution
A method involving a graded electrostatic lens configuration with variable-control suppression/focusing electrodes, where electrode voltages are adjusted to maintain an arcuate motion of the ion beam, allowing for small adjustments in deflect angle and constraining the vertical position, enabling independent tuning of beam position and angle at the wafer plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electrostatic deceleration lenses are used to decelerate ion beams, then ion energy can be controlled, but independent control of beam deflection and focus is lost due to voltage dependence on beam energy and current
Solution Approach 1:
The deceleration lens is divided into multiple independently controllable electrode sections (entrance electrode, intermediate electrodes, exit electrode) along the beam path. Each electrode can be controlled by separate voltage sources, allowing independent adjustment of beam energy and deflection. This segmentation enables the beam to be decelerated while maintaining separate control over its trajectory and focus, resolving the coupling problem in conventional single-voltage lenses.
Solution Approach 2:
The system employs dynamic voltage control where the voltage applied to each electrode can be adjusted in real-time based on beam conditions. This dynamic adjustment capability allows the lens to adapt to different beam energies and currents while maintaining independent control of deflection and focus parameters, transforming a static system into a flexible, controllable one.
2Adaptability or versatility
If voltage is adjusted to control beam deflection in conventional lenses, then deflection angle changes, but beam position and angle cannot be tuned independently due to energy dependence
Solution Approach 1:
By segmenting the lens into multiple electrodes with independent voltage control, the system can adjust deflection angle through one electrode while compensating position shifts with another electrode. This allows independent tuning of beam angle and position parameters that were previously coupled in conventional single-voltage systems.
Solution Approach 2:
The system changes multiple voltage parameters simultaneously to achieve desired beam characteristics. By varying the voltage on different electrodes in coordinated ways, the system can independently control beam energy, deflection angle, and position, providing the adaptability needed for precise beam shaping without the trade-offs of conventional approaches.
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 approach allows for precise control of ion beam deflection and focus, achieving higher quality beams with improved energy management and reduced aberrations, even for low energy output beams, by using a few 'virtual knobs' to adjust the grading and deflection factor, thereby simplifying complex power supply control.
Implementation Method 1
A method is disclosed for controlling deflection of an ion beam, comprising: providing an electrode configuration comprising a plurality of upper and lower electrode pairs, the upper and lower electrodes of each pair positioned on opposite sides of an ion beam; grading a deceleration of the ion beam
Implementation Method 2
System and method for controlling deflection of a charged particle beam within a graded electrostatic lens
Implementation Method 3
obtaining electrode voltages for the plurality of upper and lower electrode pairs to adjust the grading, the deflection factor, and a focus of the ion beam
Data Source
AI summary
A method and apparatus for controlling deflection, deceleration, and focus of an ion beam are disclosed. The apparatus may include a graded deflection/deceleration lens including a plurality of upper and lower electrodes disposed on opposite sides of an ion beam, as well as a control system for adjusting the voltages applied to the electrodes. The difference in potential between pairs of upper and lower electrodes are varied using a set of “virtual knobs” that are operable to independently control deflection and deceleration of the ion beam. The virtual knobs include control of beam focus and residual energy contamination, control of upstream electron suppression, control of beam deflection, and fine tuning of the final deflection angle of the beam while constraining the beam's position at the exit of the lens. In one embodiment, this is done by fine tuning beam deflection while constraining the beam position at the exit of the VEEF. In another embodiment, this is done by fine tuning beam deflection while measuring the beam position and angle at the wafer plane. In a further embodiment, this is done by tuning a deflection factor to achieve a centered beam at the wafer plane.