Wafer Centering with On-the-Fly Thermal Expansion Compensation
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Solution Overview
Problem
Conventional substrate processing systems face challenges in accurately centering substrates without disturbing the environment and require additional instrumentation or modifications, especially when dealing with temperature transients and non-linear kinematic effects.
Innovation Solution
The system employs automatic substrate centering using existing sensors and commands, eliminating the need for centering fixtures and software changes, and compensates for thermal expansion and hysteresis effects by determining the substrate center relative to the end effector reference point through datum features and thermal balance algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual substrate centering fixtures are used to define reference location, then substrate positioning accuracy is improved, but operator errors and particle contamination increase
Solution Approach 1:
The substrate itself serves as the reference by utilizing its own physical features (edges, corners, or patterned structures) to define its center position. The substrate processing robot detects these features directly on the substrate without requiring external fixtures, enabling the substrate to self-reference its own position and eliminate contamination from manual fixture handling.
2Manufacturing precision
If substrate centering fixtures are manually placed and used for teaching robot locations, then positioning precision is improved, but production time is reduced due to environment disturbance
Solution Approach 1:
The substrate centering is performed continuously during normal substrate processing operations rather than requiring separate manual setup steps. The robot detects substrate features during regular pick-and-place cycles, allowing location teaching to occur continuously without interrupting the vacuum environment or stopping production for manual fixture installation and removal.
3Device complexity
If conventional arm temperature compensation algorithms are used, then thermal expansion compensation is simplified, but position accuracy deteriorates during temperature transients
Solution Approach 1:
The system implements feedback by continuously monitoring the actual positions of substrate features during robot operations and comparing them against expected positions based on temperature compensation models. This feedback loop allows the system to detect and correct deviations caused by temperature transients, improving accuracy during dynamic thermal conditions while maintaining a relatively simple compensation framework.
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 enables precise substrate centering without disrupting the processing environment, reducing machine downtime and errors, and accurately compensates for thermal and kinematic variations, ensuring accurate placement across varying temperatures.
Implementation Method 1
determine an amount of thermal expansion or contraction of the substrate transport robot
Implementation Method 2
a sensor detects transitions of the substrate or end effector features
Data Source
AI summary
Substrate processing apparatus including a wafer transport apparatus with a transport arm including an end effector, an arm pose deterministic feature integral to the substrate transport apparatus and disposed so that a static detection sensor of the substrate processing apparatus detects at least one edge of the at least one arm pose deterministic feature on the fly with radial motion of the transport arm, and a controller configured so that detection of the edge effects a determination of a proportion factor identifying at least a thermal expansion variance of the transport arm on the fly and includes a kinematic effects resolver configured to determine, from the detection of the edge on the fly, a discrete relation between the determined proportion factor and each different discrete variance respective to each different link of the transport arm determining at least the thermal expansion variance of the transport arm on the fly.