Magnetic Sensor Assembly With Membrane-Isolated Carrier Position Sensing
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Solution Overview
Problem
Conventional magnetic sensors interfere with the ability of substrate transfer systems to levitate and convey magnetically levitated carriers, making precise and reliable transportation of substrates challenging in semiconductor processing.
Innovation Solution
A magnetic sensor assembly comprising a housing with a membrane separating regions, a magnetic levitation actuator assembly, and sensor assemblies that include first and second sensors to detect distances from a sinusoidal element of the carrier, allowing precise position detection without disrupting levitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional magnetic sensors are used to detect carrier position, then position detection is enabled, but the magnetic fields generated by the sensors interfere with the levitation system's ability to levitate and convey the carrier
Solution Approach 1:
A non-magnetic membrane is introduced as an intermediary between the magnetic sensor and the carrier. The membrane allows magnetic field lines to pass through while physically separating the sensor from the carrier, enabling position detection without the sensor's magnetic field interfering with the levitation system. This mediator resolves the contradiction by decoupling the detection function from the levitation function.
Solution Approach 2:
The patent replaces conventional magnetic sensors with a capacitive sensing system that uses electrical fields instead of magnetic fields to detect carrier position. The capacitive sensor measures changes in capacitance as the carrier approaches, allowing position detection without generating magnetic fields that would interfere with the levitation system.
2Measurement precision
If magnetic sensors are placed close to the carrier for accurate position detection, then measurement precision improves, but the magnetic interference with the levitation system increases
Solution Approach 1:
The non-magnetic membrane serves as a physical barrier that allows the sensor to be positioned close to the carrier for accurate detection while preventing direct magnetic field interaction. The membrane transmits magnetic field lines but blocks the sensor's magnetic field from reaching the carrier and interfering with levitation.
Solution Approach 2:
A thin non-magnetic membrane is used to separate the sensor from the carrier. This thin film allows for close proximity sensing (maintaining measurement precision) while the non-magnetic material properties prevent magnetic field interference with the levitation system.
3Measurement precision
If the sensor assembly is designed with multiple sensors spaced apart to detect sinusoidal profile, then position detection precision improves, but device complexity increases
Solution Approach 1:
The carrier incorporates a sinusoidal profile on its surface, which when detected by the sensor array, provides rich positional information. The curved sinusoidal geometry allows multiple sensors spaced apart to detect different phases of the waveform, enabling precise position determination through signal processing rather than requiring complex mechanical sensor arrangements.
Solution Approach 2:
The sinusoidal profile creates periodic variations in the detected signal as the carrier moves. This periodic pattern allows the system to determine position by analyzing the phase and amplitude of the periodic signals from multiple sensors, simplifying the overall system architecture while maintaining high precision.
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
Enables precise detection of carrier position within vacuum environments, ensuring smooth and reliable transportation of substrates by minimizing interference with the levitation system.
Implementation Method 1
the first sensor element and second sensor element are configured to measure magnetic flux density, wherein the magnetic flux generated by the at least one magnet is configured to pass through the first sensor element in a first direction and pass through the second sensor element in a second direction that is opposite to the first direction
Implementation Method 2
a magnetically levitated carrier to move the substrates through and between each of the process chambers
Implementation Method 3
a plurality of stators configured to levitate and drive a carrier within the second region
Data Source
AI summary
A process station includes: a housing; a membrane disposed in the housing, the membrane isolating a first region within the housing from a second region within the housing; a first magnetic levitation actuator assembly disposed in the first region, the first magnetic levitation assembly including: a plurality of stators configured to levitate and drive a carrier within the second region; a plurality of sensor assemblies, each sensor assembly including: a first sensor configured to detect a first distance between the membrane and a first portion of a first upper surface of a first sinusoidal element of the carrier, the first upper surface defining a sinusoidal profile; and a second sensor configured to detect a second distance between the membrane and a second portion of the first upper surface of the first sinusoidal element, and wherein the second sensor is spaced apart from the first sensor by a spacing distance.