Dual Faraday Sensor Beam Profiling for Uniform Ion Implantation
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Solution Overview
Problem
Existing ion implantation systems face challenges in achieving uniform beam current distribution across a workpiece due to position-dependent and non-repeatable temporal variations in the ion beam current.
Innovation Solution
A system and method utilizing two Faraday sensors, one movable and one stationary, to measure and separate position-dependent and temporal variations in the ion beam current, allowing for the creation of a corrected beam current profile that adjusts the scan speed of the scanner to achieve uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single movable Faraday sensor is used to measure beam current profile, then position dependent variations can be measured, but temporal variations are also included in the measurements reducing accuracy
Solution Approach 1:
The measurement system is segmented into two independent sensors: a movable Faraday sensor for capturing position-dependent beam current variations and a stationary reference Faraday sensor for capturing temporal variations. By dividing the measurement function between these two segments, the system can separately identify and correct different types of variations, thereby improving both measurement precision and reliability.
Solution Approach 2:
The stationary reference Faraday sensor acts as an intermediary that measures only temporal variations in beam current. This reference measurement serves as a mediator to identify and subtract temporal noise from the movable sensor's measurements, allowing the system to isolate position-dependent variations with higher accuracy and repeatability.
2Manufacturing precision
If scan speed is adjusted based on raw beam current profile data, then position dependent variations can be compensated, but non-repeatable temporal variations cause suboptimal tuning results
Solution Approach 1:
The system implements a feedback mechanism where the stationary reference sensor continuously monitors temporal variations in beam current. This feedback information is used to correct the measurements from the movable sensor before generating the scan speed profile, ensuring that position-dependent variations are accurately compensated while temporal variations are eliminated, leading to consistent and reliable tuning results.
Solution Approach 2:
Before using beam current profile data to adjust scan speed, the system performs a preliminary correction step by subtracting temporal variations identified by the reference sensor. This preliminary action ensures that only position-dependent variations are used for scan speed optimization, improving the reliability and consistency of the final tuning results.
3Ease of operation
If the scanner moves at uniform speed, then the system operation is simple, but position dependent variations cause non-uniform beam current distribution across the workpiece
Solution Approach 1:
The system transitions from a static uniform scan speed approach to a dynamic scan speed profile that varies with position. By using the corrected beam current profile (free of temporal variations) to generate a position-dependent scan speed profile, the scanner dynamically adjusts its speed to compensate for position-dependent variations, achieving uniform beam current distribution while maintaining operational simplicity through automated control.
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 method significantly reduces temporal variations by at least 90%, resulting in a more accurate and repeatable beam current profile that enhances the uniformity of ion implantation across the workpiece.
Implementation Method 1
The system includes two Faraday sensors; one which is moved across the ion beam and a second that remains at or near a certain location. The reference Faraday sensor is used to measure temporal variations in the beam current
Data Source
AI summary
A system and method for creating a beam current profile that eliminates variations that are not position dependent is disclosed. The system includes two Faraday sensors; one which is moved across the ion beam and a second that remains at or near a certain location. The reference Faraday sensor is used to measure temporal variations in the beam current, while the movable Faraday sensor measures both the position dependent variations and the temporal variations. By combining these measurements, the actual position dependent variations of the scanned ion beam can be determined. This resultant beam current profile can then be used to control the scan speed of the electrostatic or magnetic scanner.