High-Temperature Calibration Disc for Wafer Placement Accuracy
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Solution Overview
Problem
Current calibration and teaching processes for electronics processing systems at room temperature result in significant thermal expansion errors due to operating temperatures, leading to inaccurate calibration values and contamination risks from battery components, especially in systems with components like aluminum that expand over 3 mm at 400 degrees C.
Innovation Solution
A calibration disc with physical features, such as chamfered edges and a solid sintered ceramic material, is used to center itself on substrate supports at operating temperatures, allowing for accurate calibration without exposing temperature-sensitive sensors, and determining offsets based on position differences to improve placement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration is performed at room temperature, then the calibration process is simple and safe, but thermal expansion errors occur at operating temperature leading to reduced accuracy
Solution Approach 1:
The patent changes the temperature parameter from room temperature to elevated operating temperature during calibration. The calibration chamber is heated to match operating conditions (e.g., 400°C), eliminating thermal expansion errors that occur when calibrating at room temperature. This ensures calibration accuracy by performing it under the same thermal conditions as actual operation.
Solution Approach 2:
The patent introduces a robot arm as an intermediary to handle the calibration disc and perform placement operations at elevated temperatures. The robot arm is specifically designed to operate in high-temperature environments, serving as a mediator between the calibration system and the heated chamber, enabling accurate calibration without exposing human operators or sensitive equipment to extreme conditions.
2Extent of automation
If batteries are used in calibration components, then automated calibration is enabled, but batteries risk expanding or exploding at operating temperatures causing contamination
Solution Approach 1:
The patent removes batteries entirely from the calibration disc and chamber components. Instead of using battery-powered automated components inside the heated chamber, the system uses a robot arm with external power supply and control systems located outside the chamber. This extraction of power sources eliminates the risk of battery expansion, explosion, and chemical contamination at operating temperatures.
Solution Approach 2:
The calibration disc is designed as a simple, non-electronic, disposable component that can withstand high temperatures. Rather than using complex automated components with batteries, the system employs a simple ceramic or metal disc that can be heated without damage, used for calibration, and then replaced if needed. This approach eliminates battery-related hazards while maintaining automation through robot arm operation.
3Measurement precision
If expensive materials are used for calibration objects and sensors, then calibration precision is improved, but system cost increases significantly
Solution Approach 1:
The calibration disc is constructed from inexpensive materials such as ceramic or metal that can withstand high temperatures without degrading. Instead of using expensive specialized sensors or calibration artifacts, the system uses a simple, durable disc that can be manufactured at low cost. The robot arm's vision system uses standard cameras and sensors that are affordable and can operate at elevated temperatures, significantly reducing overall system cost while maintaining calibration accuracy.
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
The method achieves high-temperature calibration with reduced errors, achieving centering accuracy within 50 microns and eliminating cumulative placement errors by utilizing the thermal expansion of chamber components for precise robot arm adjustments.
Implementation Method 1
The elevated process temperature results in thermal expansion of components of the station or processing chamber, introducing error into the calibration values. At operating temperatures over 400 degrees C., some chamber components, made out of aluminum for example, could expand over 3 mm due to thermal expansion.
Data Source
AI summary
A calibration disc is inserted into a processing chamber using a robot arm. A first position of a center of the calibration disc is determined using one or more sensors positioned at a port of the processing chamber. The calibration disc is placed onto a substrate support within the processing chamber and features of the calibration disc cause the calibration disc to become centered on the substrate support. The calibration disc is removed from the substrate support and the processing chamber by the robot arm. A second position of the center of the calibration disc is determined using one or more sensors as the calibration is removed from the processing chamber. A difference is determined between the first and second position of the center of the calibration disc. An offset is determined to apply to the robot arm when placing wafers onto the substrate support based on the difference.