Wafer Twist And Tilt Verification Using Optical Diffraction
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Solution Overview
Problem
Existing ion implantation systems face challenges in accurately determining and correcting the twist and tilt angles of semiconductor wafers due to environmental conditions and complex sensor integration issues, leading to alignment errors that affect dose uniformity and implant accuracy, especially in high-energy implants and three-dimensional structures.
Innovation Solution
A system utilizing a light beam, such as a laser, to project an incident beam at an oblique angle on the workpiece, creating a diffraction pattern that is imaged to determine twist and tilt angles, allowing for real-time adjustment of the workpiece position and alignment without the need for sensors in harsh environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional sensors are used to measure workpiece alignment in harsh environments, then measurement capability is provided, but reliability and measurement precision deteriorate due to environmental conditions
Solution Approach 1:
The patent introduces an optical intermediary system consisting of a light source and camera that mediates the measurement process. Instead of placing sensors directly in the harsh vacuum environment, the system uses optical fields (light beams) to interact with the workpiece and transmit alignment information to a camera positioned in a controlled environment, thereby protecting the sensing components while maintaining measurement capability
Solution Approach 2:
The patent replaces mechanical/electronic sensor systems with an optical measurement system. By using light diffraction patterns and optical imaging instead of physical sensors, the system eliminates the reliability issues associated with electronic components in harsh environments while achieving high measurement precision for workpiece alignment
2Measurement precision
If complex sensor integration is implemented to achieve accurate alignment measurement, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent extracts the measurement function from complex sensor integration and implements it through a simple optical setup. By separating the measurement function into independent optical components (light source, diffraction pattern, camera) rather than integrating multiple sensors, the system achieves high measurement precision while significantly reducing device complexity and integration difficulty
3Manufacturing precision
If real-time alignment correction is implemented, then manufacturing precision improves, but device complexity and processing time increase
Solution Approach 1:
The patent performs preliminary alignment measurement using the optical diffraction system before the ion implantation process begins. By measuring and correcting workpiece alignment in advance rather than during the actual implantation, the system achieves high manufacturing precision without requiring complex real-time adjustment mechanisms, thereby reducing device complexity
Solution Approach 2:
The patent creates an optical copy or representation of the workpiece alignment state through diffraction patterns. Instead of directly manipulating the physical workpiece during implantation, the system uses optical field interactions to generate measurable patterns that represent alignment deviations, enabling precise correction through simpler optical means rather than complex mechanical adjustments
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 precise determination and correction of twist and tilt angles, improving dose uniformity and implant accuracy by compensating for alignment errors, thereby enhancing the quality of semiconductor fabrication processes.
Implementation Method 1
A diffraction pattern of the incident beam that is reflected off the workpiece is imaged
Implementation Method 2
The incident beam reflects off the surface of the workpiece
Data Source
AI summary
A light source directs an incident beam at a surface of the workpiece on a stage at an oblique angle. A detector images a diffraction pattern of the incident beam reflected off the workpiece. At least one of a twist angle and a tilt angle of the workpiece on the stage is determined based on the diffraction pattern. The workpiece may be a semiconductor wafer and the stage may be, for example, part of an ion implanter.