Vertical Ion Beam Profile Measurement Using Magnetic Deflection
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Solution Overview
Problem
Ion implantation systems lack the capability to measure the vertical profile of ion beams, leading to inefficient beam utilization and potential doping errors due to unknown beam sizes, which affects the uniformity and dose rate of dopant implantation in semiconductor wafers.
Innovation Solution
A vertical beam angle measurement device with an extended mask and a Faraday cup system is used to measure the vertical beam profile by correlating the dose cup beam current change with the tilt angle, allowing for precise determination of the ion beam's vertical size and profile, thereby optimizing beam utilization and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If scan widths are set assuming an excessively large beam size, then uniform dose coverage is ensured, but beam utilization efficiency is lowered
Solution Approach 1:
The patent replaces mechanical beam size measurement methods with a magnetic field-based deflection system. By using magnetic fields to deflect the ion beam and measure its vertical profile, the system can accurately determine the actual beam size without mechanical interference, enabling optimized scan width settings that improve beam utilization while maintaining uniform dose coverage.
2Reliability
If ion beam size is unknown, then safe uniform dose coverage can be achieved with overscan, but doping characteristics cannot be optimized
Solution Approach 1:
The patent implements a feedback mechanism where the vertical beam profile is measured using magnetic field deflection, and this measurement information is fed back to optimize the implantation process parameters. The measured beam size data enables precise adjustment of scan widths and positioning to achieve optimal doping characteristics while maintaining uniform coverage, eliminating the need for conservative overscan assumptions.
3Productivity
If vertical beam profile measurement capability is added, then beam utilization can be optimized, but device complexity increases
Solution Approach 1:
The patent designs the magnetic field deflection system to serve multiple functions: it measures the vertical beam profile, determines beam size, and can potentially adjust beam positioning. By making the measurement system multi-functional, the patent reduces overall device complexity while achieving the goal of optimizing beam utilization through accurate vertical profile measurement.
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 solution enables more accurate and efficient ion implantation by maximizing beam utilization, improving throughput and energy efficiency, and ensuring uniform doping across semiconductor substrates.
Implementation Method 1
a mass analysis apparatus for directing and/or filtering (e.g., mass resolving) the ions within the beam using magnetic fields
Implementation Method 2
a dopant material is ionized and an ion beam is generated therefrom
Data Source
AI summary
An ion implantation system measurement system has a scan arm that rotates about an axis and a workpiece support to translate a workpiece through the ion beam. A first measurement component downstream of the scan arm provides a first signal from the ion beam. A second measurement component with a mask is coupled to the scan arm to provide a second signal from the ion beam with the rotation of the scan arm. The mask permits varying amounts of the ion radiation from the ion beam to enter a Faraday cup based on an angular orientation between the mask and the ion beam. A blocking plate selectively blocks the ion beam to the first faraday based on the rotation of the scan arm. A controller determines an angle and vertical size of the ion beam based on the first signal, second signal, and orientation between the mask and ion beam as the second measurement component rotates.