Electrostatic Chuck Temperature Measurement Using Fiber Bragg Gratings
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Solution Overview
Problem
Existing electrostatic chuck assemblies in semiconductor manufacturing face challenges in accurately measuring temperature distribution across multiple zones, leading to inefficient temperature control due to the limited number of sensors, which increases costs and complexity while reducing reliability.
Innovation Solution
An electrostatic chuck assembly with a reference temperature sensor and measurement zone temperature sensors using fiber Bragg gratings (FBGs) along an optical fiber, allowing for precise temperature measurement across multiple zones by setting a measurement range based on the reference temperature, enabling accurate temperature calculation for each zone without the need for a large number of optical fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple temperature sensors are installed at various positions on the ESC to accurately measure temperature distribution, then measurement precision is improved, but device complexity and cost increase linearly with the number of sensors
Solution Approach 1:
Multiple temperature sensing functions are merged into a single optical fiber by integrating multiple FBG sensors along its length. This allows simultaneous measurement of temperatures at multiple zones of the ESC without requiring multiple separate sensor installations, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent transitions from spatial distribution of multiple discrete sensors to a linear distribution along the optical fiber dimension. By arranging FBG sensors at different positions along the fiber length, temperature measurement capability is extended across multiple ESC zones without increasing the number of fiber connections or sensor mounting points.
2Adaptability or versatility
If the temperature measurement range of the sensor is increased to cover various zones, then measurement versatility is improved, but wavelength interference occurs making it difficult to distinguish individual temperature signals
Solution Approach 1:
The temperature measurement range is segmented into multiple discrete FBG reflection wavelengths, each corresponding to a specific zone on the ESC. By assigning unique wavelengths to different spatial positions along the fiber, the system achieves broad measurement versatility while maintaining clear signal distinction through wavelength multiplexing.
Solution Approach 2:
The patent employs periodic modulation of light wavelengths through the FBG structure, where each FBG reflects a specific wavelength periodically along the optical fiber. This periodic wavelength assignment allows the system to handle a wide temperature measurement range while preventing interference by systematically spacing wavelengths apart.
3Measurement precision
If a large number of optical fibers are used to measure temperature at various positions, then measurement precision is improved, but cost and complexity increase while reliability decreases
Solution Approach 1:
Multiple optical fiber functions are merged into a single fiber by integrating multiple FBG temperature sensors along its length. This consolidation maintains the ability to measure temperatures at various ESC positions while dramatically reducing the number of fiber connections, sensor mountings, and signal processing channels required.
Solution Approach 2:
A single optical fiber is designed to perform multiple temperature measurement functions simultaneously by incorporating multiple FBG sensors at different positions. This multi-functional fiber replaces what would traditionally require multiple separate fibers, reducing system complexity while maintaining comprehensive temperature monitoring capability across all ESC zones.
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 solution allows for efficient and accurate temperature control of the electrostatic chuck and substrate, reducing costs and complexity while improving reliability by enabling dense connection of FBGs on a single optical fiber without interference, thus enhancing the quality of integrated circuit devices.
Implementation Method 1
various types of sensors have been proposed in order to measure temperatures at a plurality of positions. One example of such a sensor is a fiber Bragg grating (FBG) sensor.
Data Source
AI summary
An electrostatic chuck assembly includes a reference temperature sensor, a measurement zone temperature sensor, and a measurement zone temperature calculator. The reference temperature sensor measures a reference temperature of the electrostatic chuck. The measurement zone temperature sensor is spaced from the reference temperature sensor on the electrostatic chuck and senses temperature signals of a plurality measurement zones of the electrostatic chuck. The measurement zone temperature calculator calculates a temperature of each of the measurement zones by setting a measurement range within a temperature range, previously determined based on the reference temperature measured by the reference temperature sensor, and measures the temperature signal of each of the measurement zones sensed by the measurement zone temperature sensor within the measurement range.