Segmented Faraday Cup Time-of-Flight Energy Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing Faraday cups cannot measure the energy of charged particles in ion beams, which is crucial for controlling the depth of ion implantation in semiconductor manufacturing, as they only determine the beam current without providing energy information.
Innovation Solution
A measurement device with a Faraday cup design featuring two segments and thresholds, allowing for the calculation of charged particle energy by measuring the time-of-flight between these thresholds, combined with a current measurement system, using equations to derive the kinetic energy independent of the charge state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional Faraday cup is used to measure beam current, then the current measurement is simple and direct, but the energy of charged particles cannot be determined
Solution Approach 1:
The Faraday cup is divided into multiple segments (first segment, second segment, third segment) with different potentials. This segmentation allows the device to measure both current and energy by detecting signals at different thresholds, resolving the contradiction between measurement capability and structural simplicity.
Solution Approach 2:
The invention adds a temporal dimension to the measurement by introducing time-of-flight calculations between multiple thresholds. Instead of only measuring current magnitude, the system now measures the time it takes for particles to traverse between segmented regions, enabling energy determination without fundamentally complicating the cup structure.
2Manufacturing precision
If ion beam energy is not controlled, then the ion implantation process is simple, but the penetration depth becomes improper or undesired
Solution Approach 1:
The segmented Faraday cup provides feedback information about both current and energy simultaneously. By measuring signals at multiple thresholds and calculating time-of-flight, the system enables real-time monitoring and control of ion beam energy, ensuring proper implantation depth without adding external measurement devices.
3Measurement precision
If multiple thresholds and segments are added to measure energy, then energy determination becomes possible, but the device complexity increases
Solution Approach 1:
The segmented Faraday cup structure serves multiple functions simultaneously: it measures total current, measures energy distribution, and provides time-of-flight information. This multi-functionality reduces the need for separate measurement devices, offsetting the increased structural complexity with consolidated measurement capabilities.
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
Enables accurate determination of charged particle energy, improving the control over ion implantation depth and allowing for real-time monitoring and correction of energy contamination, with sensitivity to 0.1% energy deviations.
Implementation Method 1
A first current signal is generated in response to a charged particle in the ion beam crossing a first threshold between the plate and the first segment of the Faraday cup. A second current signal is generated in response to the charged particle crossing a second threshold between the first segment and the second segment of the Faraday cup. The time-of-flight between the first current signal and the second current signal is measured, and the energy of the charged particle is calculated
Implementation Method 2
Faraday cups are typically metal or graphite devices that catch charged particles, such as ions or electrons, in a vacuum. As the charged particles enter the Faraday cup, the resulting current is measured to determine the number of charged particles impacting the Faraday cup
Data Source
AI summary
This measurement device is used to determine energy for charged particles. The measurement device includes two segments and a plate that define two thresholds or gaps. The current as a charged particle passes through these thresholds or gaps is measured. The measurement device then calculates the energy of the charged particles. Energy contamination also may be determined.