Ion Beam Dithering for Uniformity in 2D Mechanical Scan Implantation
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Solution Overview
Problem
Two-dimensional scanning systems in ion implantation processes face challenges in achieving uniformity and productivity due to slower scan speeds and reduced micro-uniformity, with prior solutions increasing total implant time to improve uniformity at the expense of productivity.
Innovation Solution
The implementation of a supplemental scanning system that dithers the ion beam along a third axis different from the fast scan direction, with a frequency substantially greater than the fast scan frequency, effectively increasing the ion beam profile and improving dose uniformity without compromising productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pitch of scan lines is decreased to improve micro-uniformity, then dose uniformity is improved, but total implant time increases reducing productivity
Solution Approach 1:
The patent introduces a third scanning axis (fast scan direction) in addition to the traditional two-dimensional scanning system. By scanning the ion beam rapidly in this additional dimension while maintaining the original scan pattern, the system achieves improved dose uniformity through increased beam displacement without requiring a decrease in scan line pitch, thus maintaining productivity.
Solution Approach 2:
The supplemental fast scan operates at a high frequency, periodically displacing the ion beam position during each main scan pass. This periodic action creates multiple effective beam positions along the scan line, improving uniformity by distributing the dose more evenly across the workpiece surface without increasing the total number of scan lines required.
2Productivity
If scan speed is increased to improve productivity, then throughput is improved, but micro-uniformity deteriorates due to reduced number of scan lines
Solution Approach 1:
By adding the fast scan dimension, the system can maintain higher scan speeds in the original dimensions while achieving improved uniformity through the supplemental scanning. The fast scan creates additional effective scan lines through beam displacement rather than requiring slower mechanical scanning.
Solution Approach 2:
The patent replaces the need for increased mechanical scan line density with an electromagnetic beam scanning mechanism. Instead of mechanically moving the workpiece or beam to create more scan lines, the system uses electromagnetic fields to rapidly displace the ion beam position, achieving the same uniformity improvement effect without the mechanical constraints.
3Adaptability or versatility
If two-dimensional mechanical scanning is used to process single substrates, then flexibility is improved, but scan speed decreases compared to batch tools
Solution Approach 1:
The fast supplemental scan operates periodically at high frequency during each main scan pass, creating the effect of multiple rapid scans without the mechanical overhead of actual multiple passes. This periodic beam displacement enables batch-tool-like speeds while maintaining single-substrate processing flexibility.
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 dose uniformity across the workpiece while maintaining high throughput, as the larger effective beam size allows for a larger scan pitch and reduced number of scan lines, optimizing both micro-uniformity and productivity.
Implementation Method 1
a supplemental scanning system configured to effectuate a supplemental scanning of the ion beam with respect to the end station along a third scan axis having a third direction that is different than the first direction
Data Source
AI summary
An ion implantation system includes a beamline configured to direct an ion beam toward an end station configured to hold or support a workpiece, and a scanning system. The scanning system is configured to scan the end station past the ion beam in a two-dimensional fashion comprising a first scan axis along a first direction and a second scan axis along a second direction that is different than the first direction. The system further includes a supplemental scanning component operably associated with the scanning system, and configured to effectuate a scanning of the ion beam with respect to the end station along a third scan axis having a third direction that is different than the first direction.