Scan and Corrector Magnet Designs for Ion Implanter Throughput
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Solution Overview
Problem
Conventional ion implantation systems face challenges in achieving high throughput and precise dopant placement at low energy implants, with limitations in minimizing beam angle variation and maintaining uniformity across the substrate surface, especially for low energy applications.
Innovation Solution
The system employs an improved design of scan and corrector magnets to create a non-uniform flux profile for the scanned ion beam, using a magnetic scanner and corrector apparatus with a time-varying potential waveform to direct the ion beam across the workpiece, providing a constant angle of incidence and adjusting the magnetic poles to optimize flux distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional scan magnets are used for low energy implants, then beam angle variation is minimized, but throughput is limited due to large scan amplitudes required
Solution Approach 1:
The patent applies local quality by providing different magnetic field characteristics at different locations within the scan magnet. The magnet is designed with a non-uniform magnetic field distribution, where the field strength varies across the scan range to compensate for the non-linear relationship between magnet current and beam deflection angle at low energies. This ensures uniform angular distribution of the beam across the substrate surface while maintaining high throughput.
Solution Approach 2:
The patent changes the magnetic field parameters of the scan magnet to optimize performance at low implant energies. By adjusting the magnetic field strength, distribution, and spatial characteristics, the system achieves both minimal beam angle variation and high throughput. The corrector magnet further adjusts these parameters to compensate for energy-dependent deflection variations.
2Productivity
If large scan amplitudes are utilized to provide full over-scan, then throughput is improved, but beam angle variation increases
Solution Approach 1:
The scan magnet is designed with spatially varying magnetic field properties that compensate for the effects of large scan amplitudes. Different regions of the magnetic field are optimized to produce appropriate deflection angles, ensuring that even with large scan ranges for high throughput, the beam maintains minimal angular variation across the substrate.
Solution Approach 2:
The system incorporates corrector magnets that provide feedback compensation for beam angle variations. The corrector magnets adjust the beam trajectory in real-time based on the scan position, compensating for any angular deviations that occur during large amplitude scanning, thus maintaining precision while achieving high throughput.
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 enhances the efficiency of ion implantation systems by increasing throughput and achieving precise dopant placement with improved uniformity and flux distribution, particularly at low energy implants, by providing greater flux at the edges of the workpiece and maintaining uniformity across the surface.
Implementation Method 1
a scan waveform having a time-varying potential is applied to the scan magnet. The ion beam is scanned by the scan magnet across a scan path
Implementation Method 2
The corrector apparatus is configured to direct the scanned ion beam toward a workpiece at a generally constant angle of incidence across the workpiece. The corrector apparatus further comprises a plurality of magnetic poles
Data Source
AI summary
An ion implantation system and method provide a non-uniform flux of a ribbon ion beam. A spot ion beam is formed and provided to a scanner, and a scan waveform having a time-varying potential is applied to the scanner. The ion beam is scanned by the scanner across a scan path, generally defining a scanned ion beam comprised of a plurality of beamlets. The scanned beam is then passed through a corrector apparatus. The corrector apparatus is configured to direct the scanned ion beam toward a workpiece at a generally constant angle of incidence across the workpiece. The corrector apparatus further comprises a plurality of magnetic poles configured to provide a non-uniform flux profile of the scanned ion beam at the workpiece.