Ion Implantation Angle Control via Sheet Resistance Feedback
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Solution Overview
Problem
Current ion implantation technologies face challenges in precisely controlling the implant angle distribution of ion beams, which affects the carrier concentration distribution in semiconductor wafers, due to difficulties in directly measuring the angle distribution and the channeling phenomenon's dependence on both average and deviation angles of ion particles.
Innovation Solution
An ion implantation method and apparatus that irradiate a wafer with an ion beam, measure specific characteristics on the wafer surface, and evaluate the implant angle distribution using sheet resistance measurements to adjust the ion beam's angle distribution in both the x and y directions, ensuring precise control of the carrier concentration distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the ion beam angle distribution is not precisely controlled, then the manufacturing process is simpler, but the manufacturing precision of carrier concentration distribution deteriorates
Solution Approach 1:
The patent employs a feedback mechanism where sheet resistance measurements are taken after ion implantation, and these measurements are used to evaluate and adjust the implant angle distribution. The controller automatically adjusts beam shaping lens parameters based on the measured sheet resistance values, creating a closed-loop control system that precisely controls carrier concentration distribution without requiring complex direct angle measurement systems.
Solution Approach 2:
The patent replaces direct mechanical or optical measurement of beam angle distribution with an indirect electrical measurement method. Instead of using complex mechanical goniometers or optical sensors to measure beam angles, the system uses sheet resistance measurements (an electrical property) to infer and control the implant angle distribution, substituting a simple electrical measurement system for a complex mechanical measurement system.
2Measurement precision
If direct measurement of implant angle distribution is performed, then measurement precision would improve, but the measurement system becomes more complex and difficult to implement
Solution Approach 1:
The patent introduces sheet resistance as an intermediary parameter that indirectly reflects the implant angle distribution. Instead of directly measuring the complex angular distribution of implanted ions, the system measures the easily obtainable sheet resistance, which serves as a mediator that correlates with the angle distribution. This intermediary measurement approach maintains measurement precision while avoiding the complexity of direct angle measurement systems.
Solution Approach 2:
The patent substitutes direct angular measurement (which would require complex mechanical or optical instrumentation) with electrical resistance measurement. By measuring sheet resistance instead of beam angles directly, the system achieves equivalent measurement precision using a much simpler electrical measurement setup rather than a complex mechanical measurement system.
3Area of stationary object
If the ion beam diverges or converges significantly, then the beam can cover larger area, but the angle distribution control precision deteriorates
Solution Approach 1:
The patent employs dynamic adjustment of beam shaping lens parameters based on real-time sheet resistance measurements. The system can adaptively change the beam angle distribution during the implantation process, allowing the beam to cover the required wafer area while maintaining precise angle control. The controller dynamically modifies lens parameters to optimize both coverage area and angle precision according to the specific implantation requirements.
Solution Approach 2:
The patent changes the parameters of the beam shaping lenses (focal length, aperture, positioning) to control the beam's divergence or convergence. By adjusting these parameters, the system can optimize the beam angle distribution to achieve the desired balance between wafer coverage area and implant angle precision. The sheet resistance measurements provide feedback to determine the optimal parameter settings for each specific case.
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 highly precise control of the implant angle distribution, resulting in optimized carrier concentration distributions and improved semiconductor wafer processing outcomes by accurately adjusting the ion beam's angle characteristics.
Implementation Method 1
the process of implanting a semiconductor wafer with ions (hereinafter, also referred to as 'ion implantation process') is generally performed for the purpose of changing the conductivity of the semiconductor, changing the crystal structure of the semiconductor
Implementation Method 2
an ion beam incident along a crystal axis or crystal plane of the wafer results in a channeling phenomenon in which implanted ions reach deeper into the wafer from the beam incident surface than otherwise
Data Source
AI summary
An ion implantation method includes: irradiating a wafer arranged to meet a predetermined plane channeling condition with an ion beam; measuring a predetermined characteristic on a surface of the wafer irradiated with the ion beam; and evaluating an implant angle distribution of the ion beam by using a result of measurement of the characteristic. The wafer may be arranged so as to include a channeling plane parallel to a predetermined reference plane parallel to a reference trajectory direction of the ion beam incident on the wafer and not to include a channeling plane perpendicular to the reference plane and parallel to the reference trajectory direction.