Test Wafer With Dual Accelerometers For Rotational Motion Detection
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Solution Overview
Problem
Existing test wafer systems for semiconductor processing do not accurately measure accelerations experienced by substrates during handling operations, as they fail to account for substrate rotation about the center of gravity, which can contribute to friction forces and potential substrate misalignment or loss.
Innovation Solution
A test wafer system with multiple accelerometers positioned at spaced-apart locations along a common axis crossing the center of gravity, allowing for accurate measurement of acceleration data, including rotational acceleration, to provide reliable feedback for improving handling operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single tri-axial accelerometer is used at the substrate center, then the device complexity is low, but the measurement precision of rotational acceleration is insufficient
Solution Approach 1:
The patent divides the measurement function by using multiple accelerometers (at least two) positioned at different locations on the substrate. Each accelerometer measures acceleration at its specific location, and the controller segments the analysis by calculating both linear acceleration at the center of gravity and rotational acceleration about the center of gravity separately, improving overall measurement precision.
Solution Approach 2:
The patent adds spatial dimensionality to the measurement system by positioning accelerometers at multiple locations rather than a single point. This dimensional expansion enables the system to capture rotational acceleration components that cannot be measured by a single-point accelerometer, transforming the measurement capability from one-dimensional (single point) to multi-dimensional (distributed points).
2Measurement precision
If multiple accelerometers are positioned at spaced-apart locations, then the measurement precision of rotational acceleration improves, but the device complexity increases
Solution Approach 1:
The controller performs multiple functions using the accelerometer data: it calculates linear acceleration at the center of gravity, calculates rotational acceleration about the center of gravity, and determines tangential acceleration components. This multi-functionality justifies the added complexity by providing comprehensive acceleration analysis from the distributed accelerometer array.
Solution Approach 2:
The controller acts as an intermediary that processes the raw acceleration data from multiple accelerometers and transforms it into meaningful rotational and tangential acceleration components. This intermediary processing layer manages the complexity by systematically computing derived parameters from the distributed sensor measurements.
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 system provides more accurate acceleration data, enabling better control of wafer handling robots to prevent substrate misalignment and loss by accounting for rotational movements, thus enhancing processing efficiency and throughput.
Implementation Method 1
a first accelerometer and a second accelerometer positioned on the platform at spaced-apart locations along a common axis that crosses the center of gravity of the apparatus when viewed along a direction perpendicular to the platform
Data Source
AI summary
A test wafer having two spaced-apart accelerometers mounted thereon is disclosed. The accelerometers may be positioned at locations located along a common axis passing through the center of gravity of the test wafer. The test wafer may include a controller that may be used to transmit acceleration data collected by the accelerometers to another device. In some implementations, a semiconductor processing tool is provided that includes a test wafer receptacle for storing a test wafer that remains with the semiconductor processing tool and that may be retrieved by a wafer handling robot for performing a test cycle during periods when the wafer handling robot is not performing substrate transport operations.