Ion Beam Focus Adjustment for Zero-Field Effect Compensation
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Solution Overview
Problem
Ion implantation systems face challenges in maintaining uniformity due to zero-field effects, which cause beam current and size variations during scanning, particularly in magnetically-scanned high current beamlines, requiring sophisticated correction algorithms and high dynamic range scanners.
Innovation Solution
The implementation of a focus adjustment component, such as a solenoid, magnetic quadrupole, or Einzel lens, that generates time-varying magnetic or electric fields to adjust the focal properties of the ion beam, compensating for zero-field effects by adjusting beam size and current density, thereby maintaining consistency across the workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a high bandwidth scanner is used to vary scan speed for uniformity correction, then implantation uniformity is improved, but device complexity and difficulty of meeting bandwidth requirements increase due to eddy-current losses
Solution Approach 1:
The patent changes the operating parameters of the scanner by introducing a compensation waveform that modifies the scan speed dynamically. This allows the scanner to operate at lower bandwidth while still achieving uniformity correction, as the compensation waveform adjusts the scan speed to account for ZFE effects without requiring the scanner to meet extremely high bandwidth specifications
Solution Approach 2:
The patent applies preliminary anti-action by introducing a compensation waveform that anticipates and counteracts the ZFE effects before they significantly impact beam uniformity. The compensation waveform is designed to pre-correct for the expected beam size and current changes that occur when the scanner field passes through zero, thereby reducing the burden on the scanner's bandwidth capabilities
2Ease of operation
If magnetic scanning is used to scan the ion beam, then scanning capability is achieved, but zero field effects cause dramatic beam current and size changes requiring sophisticated correction algorithms
Solution Approach 1:
The patent implements feedback by using beam profiling measurements to determine the actual beam size and current variations caused by ZFE effects. This measured information is then fed back into the system to generate or adjust the compensation waveform, creating a closed-loop system that continuously corrects for beam variations and maintains consistency without requiring complex correction algorithms
Solution Approach 2:
The patent applies dynamics by making the scan waveform dynamic and adaptive rather than static. The compensation waveform is adjusted based on real-time beam profiling measurements, allowing the system to dynamically respond to ZFE effects and maintain beam consistency. This dynamic approach replaces the need for sophisticated static correction algorithms
3Productivity
If bipolar scanning is used to scan the ion beam across the workpiece, then scanning efficiency is improved, but zero field effects cause beam neutralization changes that affect beam size and current
Solution Approach 1:
The patent introduces an intermediary element - the compensation waveform - that mediates between the bipolar scanning operation and the beam neutralization stability issue. This compensation waveform acts as a buffer that counteracts the neutralization changes caused by the scanner field passing through zero, allowing bipolar scanning to maintain its efficiency while preserving beam stability
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 solution effectively mitigates the adverse effects of zero-field effects, ensuring consistent ion implantation uniformity and beam profile across the workpiece by dynamically adjusting focal properties in response to scanner field changes, enhancing the scanner's dynamic range and reducing abrupt flux variations.
Implementation Method 1
a scanner configured to scan the ion beam across a workpiece by generating a magnetic field that interacts with the ion beam to induce an angular deflection
Implementation Method 2
acts as a time-varying lens that dynamically changes the focal properties of the beam as the beam is scanned
Implementation Method 3
the field of the scanner may also affect the properties of the ion beam in an unintended, and perhaps undesirable, manner by interacting via changes in the space-charge neutralization of the beam
Data Source
AI summary
Ion implantation systems and scanning systems are provided, in which a focus adjustment component is provided to adjust a focal property of an ion beam to diminish zero field effects of the scanner upon the ion beam. The focal property may be adjusted in order to improve the consistency of the beam profile scanned across the workpiece, or to improve the consistency of the ion implantation across the workpiece. Methods are disclosed for providing a scanned ion beam to a workpiece, comprising scanning the ion beam to produce a scanned ion beam, adjusting a focal property of an ion beam in relation to zero field effects of the scanner upon the ion beam, and directing the ion beam toward the workpiece.