Optical End Effector Calibration for Plasma Chuck Alignment
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Solution Overview
Problem
Existing end effector calibration methods for plasma processing systems are inefficient due to the need for multiple mechanical fixtures, potential chuck damage, particle contamination, and inaccurate alignment caused by manual calibration at atmospheric pressure, which does not replicate production conditions.
Innovation Solution
An optical calibration method using a light beam from the end effector to detect discontinuities on the chuck surface, allowing the robot arm controller to determine the chuck center and align the end effector without a physical fixture, thus eliminating the need for manual alignment and reducing contamination risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual calibration using mechanical fixtures is used, then alignment can be achieved, but particle contamination and chuck damage occur
Solution Approach 1:
The patent replaces the mechanical calibration fixture system with an optical system. A light source projects a light beam across the chuck surface, and a sensor detects the light beam position. This optical method eliminates mechanical contact between calibration tools and the chuck, preventing particle generation and contamination while maintaining alignment accuracy.
Solution Approach 2:
The patent introduces light as an intermediary medium for calibration. Instead of direct mechanical contact between fixtures and the chuck, light serves as the mediator that carries alignment information. The light beam traverses the chuck surface without physical contact, enabling precise measurement while avoiding contamination.
2Measurement precision
If multiple mechanical fixtures are used for calibration, then alignment can be achieved, but device complexity increases
Solution Approach 1:
The patent extracts the essential calibration function from complex mechanical fixtures and implements it through a simplified optical system. Instead of using multiple mechanical components, the invention uses a light source, light beam, and sensor arrangement that achieves the same alignment measurement purpose with fewer elements.
Solution Approach 2:
The optical calibration system serves multiple calibration functions with a single setup. The light source and sensor arrangement can determine both the position and orientation of the chuck relative to the end effector, replacing what previously required multiple specialized mechanical fixtures for different measurement tasks.
3Ease of operation
If calibration is performed at atmospheric pressure, then calibration can be completed, but alignment accuracy decreases due to pressure differential effects
Solution Approach 1:
The patent replaces mechanical contact-based calibration with optical measurement. Since light transmission is not affected by pressure differentials, the optical system can accurately measure chuck position and orientation regardless of whether the chamber is at atmospheric pressure or vacuum, eliminating the source of calibration error.
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 method provides accurate and reliable end effector alignment, reducing particle contamination and the need for multiple fixtures, while ensuring calibration conditions mirror production environments, leading to improved wafer placement accuracy and reduced production failures.
Implementation Method 1
receiving a set of reflected light signals, the set of reflected light signals being generated at least when the surface reflects the first light beam during the moving
Data Source
AI summary
A method for calibrating alignment of an end effector with respect to a chuck in a plasma processing system is disclosed. The method includes providing a first light beam from the end effector to said chuck, moving the end effector along a predefined calibration path such that the first light beam traverses a surface of the chuck, receiving a set of reflected light signals being generated at least when the surface reflects the first light beam during the moving, and analyzing the set of reflected light signals to identify three or more discontinuities, generated when the first light beam encounters an edge of the chuck. The method also includes determining three or more coordinate data points representing three or more points on the edge of the chuck, and determining a center of the chuck based on the three or more coordinate data points.