Ion Beam Profiling Speed Enhancement for Scanned Implanters
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Solution Overview
Problem
Ion beam profiling in ion implantation systems is excessively time-consuming due to low scan frequencies required for accurate dosimetry, leading to reduced throughput and long measurement times, especially when using a Faraday cup to integrate ion beam current over multiple spatial points.
Innovation Solution
Perform ion beam profiling at a significantly higher scan frequency than used during actual implantation, allowing for faster measurement times, and then adjust the scan frequency back to the implantation frequency for final checks and corrections, utilizing a controller to tune the ion beam based on properties measured at the higher frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ion beam profiling is performed at low scan frequency to ensure accurate dosimetry, then measurement accuracy is improved, but measurement time increases excessively
Solution Approach 1:
The patent applies periodic action by performing beam profiling at multiple different scan frequencies. Multiple profiles are acquired at different frequencies, and these profiles are combined to create a final composite profile. This approach allows the system to capture accurate dosimetry information while reducing the total time required compared to performing all measurements at a single low frequency.
Solution Approach 2:
The patent changes the scan frequency parameter across multiple measurement cycles. By varying the scan frequency and combining the resulting profiles, the system achieves both accurate dosimetry (which requires low frequency) and reduced measurement time (achieved through higher frequency measurements). The composite profile synthesis algorithm reconciles measurements taken at different frequency parameters.
2Reliability
If multiple beam profiles are measured to reduce noise effects, then measurement reliability is improved, but throughput is compromised due to long profiling times
Solution Approach 1:
The system performs periodic measurements at varying scan frequencies rather than repeatedly at the same low frequency. This periodic variation allows multiple profiles to be acquired for noise reduction while the higher frequencies reduce the time required for each profile, thereby maintaining reliability while improving throughput.
Solution Approach 2:
The patent performs preliminary beam profiling measurements at high scan frequencies to quickly establish beam characteristics. These preliminary high-frequency profiles are then combined with fewer low-frequency profiles, reducing the total number of measurements needed while maintaining noise reduction benefits.
3Measurement precision
If Faraday cup dwells at each spatial point to integrate current over full beam profile, then measurement accuracy is improved, but measurement time increases
Solution Approach 1:
The patent changes the scan frequency parameter during profiling operations. By performing measurements at multiple frequencies and combining the results, the system achieves accurate current integration (which benefits from longer dwell times at low frequency) while reducing total measurement time through the contribution of faster high-frequency profiles.
Solution Approach 2:
The system uses periodic measurements at different scan frequencies to accumulate sufficient current integration data. Rather than requiring one extremely long dwell time, the system accumulates integrated current information across multiple periodic cycles at varying frequencies, achieving the same integration accuracy with reduced total time.
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 significantly reduces measurement time for ion beam profiling, enhancing throughput by allowing faster determination of ion beam profiles without compromising accuracy, and enables corrections to be applied based on differences in frequency responses.
Implementation Method 1
an ion source configured to generate an ion beam having an ion beam current associated therewith
Implementation Method 2
a beam scanner configured to scan the ion beam along a scan plane
Implementation Method 3
a Faraday cup configured to translate through the scanned ion beam and measure one or more properties of the scanned ion beam
Data Source
AI summary
An ion implantation system and method are provided where an ion beam is tuned to a first process recipe. The ion beam is scanned along a scan plane at a first frequency, defining a first scanned ion beam. A beam profiling apparatus is translated through the first scanned ion beam and one or more properties of the first scanned ion beam are measured across a width of the first scanned ion, thus defining a first beam profile associated with the first scanned ion beam. The ion beam is then scanned at a second frequency, thus defining a second scanned ion beam, wherein the second frequency is less than the first frequency. A second beam profile associated with the second scanned ion beam is determined based, at least in part, on the first beam profile. Ions are subsequently implanted into a workpiece via the second scanned ion beam.