Curved Post Scan Electrode for Ion Implanter Beam Refraction
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Solution Overview
Problem
Conventional ion implanters with flat post scan electrodes cause an undesirable shift of the apparent scan origin due to beam refraction, leading to compromised dosimetry accuracy and process parameters.
Innovation Solution
An ion implanter system with a post scan electrode having a curved or arced shape that maintains the apparent scan origin at the same position as the actual scan origin, preventing refractive shifts and allowing for higher voltage usage without compromising beam parallelism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a flat post scan electrode is used, then the device structure is simple, but the apparent scan origin shifts downstream due to beam refraction
Solution Approach 1:
The post scan electrode surface is changed from flat to curved (cylindrical or spherical curvature). This curvature compensates for the beam refraction effect, causing the refracted beam paths to converge at the correct scan origin position rather than shifting downstream. The curved surface normal at each point is oriented to redirect beams appropriately.
2Ease of manufacture
If a flat post scan electrode is used, then manufacturing is easier, but dosimetry accuracy is compromised
Solution Approach 1:
The curved surface geometry of the post scan electrode corrects the beam refraction-induced shift in apparent scan origin, thereby restoring accurate dosimetry measurements. The curvature is specifically designed to counteract the refraction effects and maintain the correct beam geometry for accurate dose delivery.
3Productivity
If higher voltage is applied to scan plates, then beam scanning performance improves, but the apparent scan origin shift increases
Solution Approach 1:
The curved post scan electrode surface is designed to compensate for the increased beam refraction effects that occur at higher scan plate voltages. By adjusting the curvature parameters, the electrode can correct for larger angular deviations while maintaining the scan origin at the correct position, thus enabling higher voltage operation without origin shift.
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 curved post scan electrode maintains accurate beam alignment and dosimetry, enabling the use of higher voltages and reducing the need for a higher collimator field, thus improving process parameters and dosimetry accuracy.
Implementation Method 1
The undesirable downstream shift of the apparent scan origin compared to the actual scan origin is caused by beam refraction associated with the flat post scan electrode.
Data Source
AI summary
An apparatus an ion beam generator to provide an ion beam. A scanning system may receive the ion beam and provide a scanned beam. An electrode may receive the scanned beam. At least a portion of the electrode is normal to a propagation direction of the scanned beam. The portion of the electrode that is normal to the propagation direction the scan beam may have a curved shape.