Wafer Carrier Ring Position Correction via Through Beam Sensors
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Solution Overview
Problem
In semiconductor processing, the misalignment of carrier rings and substrates during transfer between locations leads to inefficiencies and potential damage, as the rotational orientation and center point of non-circular substrates are critical for precise alignment, and existing methods fail to accurately determine these positions, especially when substrates have varying diameters and angular orientations.
Innovation Solution
A method and system that utilize through beam sensors to detect sensor transitions as a carrier ring assembly passes through a position detection system, allowing for the calculation of its center point and angular rotation, enabling corrective movements of the end effector to ensure proper alignment and fit through narrow openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional center finding methods are used for substrates with constant radius, then the center point can be determined, but the method fails when substrates have varying diameters or non-circular shapes
Solution Approach 1:
The patent changes the measurement parameters from assuming a constant radius to measuring actual radial distances at multiple angular positions. By measuring the distance from the center to the substrate edge at multiple angles and using these varying measurements to calculate the center, the system adapts to substrates with non-uniform diameters and irregular shapes, resolving the contradiction between measurement precision and adaptability.
2Ease of operation
If the substrate is circular and rotational orientation is not critical, then alignment is simpler, but when the substrate is non-circular, rotational orientation becomes critical and alignment difficulty increases
Solution Approach 1:
The patent performs preliminary measurement of the substrate's rotational orientation and position before the transfer operation. By measuring the actual orientation angles and center position in advance, the system can pre-calculate the necessary correction values and adjust the end effector accordingly, making the alignment process straightforward regardless of whether the substrate is circular or non-circular.
3Productivity
If the end effector transfers the carrier ring assembly without position correction, then the transfer speed is maintained, but misalignment occurs leading to potential damage and reduced efficiency
Solution Approach 1:
The system performs position and orientation measurements and calculates correction values before the transfer operation begins. This preliminary correction calculation allows the end effector to adjust its position and orientation in advance, ensuring accurate alignment upon placement without slowing down the transfer process, thus maintaining both productivity and reliability.
Solution Approach 2:
The patent implements a feedback mechanism where the measured position and orientation data from the substrate is used to calculate correction values that are applied to the end effector's movement. This closed-loop feedback ensures that any deviations in substrate position or orientation are compensated for, maintaining high alignment accuracy while preserving transfer speed.
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 accurate positioning and alignment of carrier rings and substrates without reducing processing tool throughput, preventing damage and ensuring proper orientation, even for substrates with non-uniform diameters, thereby improving processing efficiency.
Implementation Method 1
passing the carrier ring assembly through a plurality of through beam sensors. A plurality of sensor transitions along points on the carrier ring assembly are detected.
Data Source
AI summary
Embodiments of the invention include apparatuses and systems for determining the position of a carrier ring assembly supported by an end effector. In an embodiment, the position of the carrier ring assembly is determined by passing the carrier ring assembly through a plurality of through beam sensors. As the carrier ring passes through the sensors, a plurality of sensor transitions along points on the carrier ring assembly are detected. Each sensor transition indicates that one of the through beam sensors changed from an unblocked state to a blocked state, or changed from an blocked state to an unblocked state. The position of the end effector is recorded at each sensor transition and is associated with the sensor transition that caused the end effector position to be recorded. A position of the carrier ring assembly is then calculated from the plurality of sensor transitions and their associated end effector positions.