Variable Scan Frequency Ion Implanter for Beam Uniformity
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Solution Overview
Problem
Conventional ion implanters face challenges in achieving uniformity of ion beam current distribution due to fixed scan frequencies, which are inadequate for both high and low energy ion beams, leading to decreased success rates and increased tune time for low energy beams.
Innovation Solution
An ion implanter with a variable scan frequency controller that adjusts the scan frequency based on the energy of the ion beam, using higher frequencies for high energy beams and lower frequencies for low energy beams to ensure adequate neutralization time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a relatively higher scan frequency is used for high energy ion beams, then beam current measurement accuracy and dose uniformity are improved, but beam neutralization time is insufficient leading to decreased beam current for low energy ion beams
Solution Approach 1:
The patent applies dynamics by making the scan frequency adjustable and variable rather than fixed. The system dynamically adapts the scan frequency based on ion beam energy levels, using higher frequencies for high energy beams and lower frequencies for low energy beams, thereby optimizing both measurement accuracy and neutralization time for different operating conditions
Solution Approach 2:
The patent changes the operational parameter of scan frequency based on the energy of the ion beam. By adjusting this parameter according to beam energy, the system achieves adequate neutralization time for low energy beams while maintaining sufficient measurement frequency for high energy beams, resolving the contradiction between measurement precision and beam stability
2Manufacturing precision
If a relatively higher scan frequency is used to provide more passes over the wafer, then dose uniformity is improved, but neutralization time is insufficient for low energy ion beams leading to increased tune time
Solution Approach 1:
The system dynamically adjusts scan frequency based on beam energy, allowing high frequency operation for high energy beams to achieve dose uniformity through multiple passes, while switching to lower frequency for low energy beams to ensure adequate neutralization time, thereby reducing overall tune time
Solution Approach 2:
By changing the scan frequency parameter according to beam energy conditions, the system optimizes the balance between achieving sufficient passes for dose uniformity and allowing adequate neutralization time, eliminating the need for extended tuning periods
3Device complexity
If a fixed scan frequency is used, then system simplicity is maintained, but performance is degraded for both high and low energy ion beams
Solution Approach 1:
The patent implements a universal scan frequency control system that can adapt to different ion beam energy conditions. The controller is designed to automatically adjust the scan frequency based on detected beam energy, making the system versatile for processing both high and low energy beams with optimal parameters for each condition
Solution Approach 2:
The system employs feedback control where the controller detects the energy of the ion beam and automatically adjusts the scan frequency accordingly. This closed-loop approach maintains high processing efficiency for both high and low energy beams while keeping the system relatively simple 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
This approach allows for better ion beam current detection and distribution uniformity for high energy beams while providing sufficient neutralization time for low energy beams, enhancing the success rate of uniformity setup and reducing tune time.
Implementation Method 1
The scanner may be an electrostatic scanner or a magnetic scanner as are known in the art
Implementation Method 2
The scanner may be an electrostatic scanner or a magnetic scanner as are known in the art
Implementation Method 3
The energetic ions in the beam penetrate into the bulk of the semiconductor material and are embedded into the crystalline lattice of the semiconductor material to form a region of desired conductivity
Implementation Method 4
One or more Faraday sensors disposed about the perimeter of the wafer to monitor ion beam current as the scanned ion beam is scanned off the front surface of the wafer
Data Source
AI summary
An ion implanter includes an ion beam generator configured to generate an ion beam, a scanner configured to scan the ion beam in at least one direction at a scan frequency, and a controller. The controller is configured to control the scan frequency in response to an operating parameter of the ion implanter. The operating parameter is at least partially dependent on the energy of the ion beam. The scan frequency is greater than a scan frequency threshold if the energy is greater than an energy threshold, and the scan frequency is less than the scan frequency threshold if the energy is less than the energy threshold.