Plasma Reflection Sensing for Substrate Frequency and Warpage
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Solution Overview
Problem
Current methods for determining the attraction state and natural frequency of substrates in plasma processing lack accuracy, particularly in detecting warpage or deflection and orientation, due to reliance on external light sources and sensitivity to plasma emission intensity.
Innovation Solution
A measuring method that utilizes light emission from plasma to detect the natural frequency of substrates by calculating changes in light amount or position, allowing for accurate determination of attraction state, warpage, and deflection without external light sources, using a photodetector with divided light receivers to measure time-dependent and position-dependent changes in light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external light sources are used to detect substrate natural frequency, then detection capability is provided, but measurement precision deteriorates due to sensitivity to plasma emission intensity and inability to detect warpage or deflection accurately
Solution Approach 1:
The plasma emission itself is utilized as the light source for detection, eliminating the need for external light sources. The plasma serves dual purposes: both processing the substrate and providing the illumination needed for measuring reflected light to determine substrate natural frequency and attraction state
Solution Approach 2:
The detection method transitions from using external light sources to using plasma emission intensity as the light source. By monitoring changes in reflected light intensity from plasma emission, the system can detect substrate natural frequency, warpage, and deflection with higher precision
2Measurement precision
If plasma emission is used as light source, then measurement precision improves for warpage and deflection detection, but device complexity increases requiring divided light receivers
Solution Approach 1:
The photodetector is divided into multiple light receivers positioned at different locations. Each light receiver detects reflected light from different regions of the substrate, enabling the system to measure warpage and deflection by comparing light intensity variations across the divided receivers
Solution Approach 2:
The detection system transitions from single-point frequency detection to two-dimensional warpage and deflection detection by arranging light receivers in different spatial positions. This dimensional expansion allows simultaneous measurement of multiple substrate parameters
3Illumination intensity
If radio frequency power is increased to generate sufficient plasma light emission, then detection signal strength improves, but energy loss increases
Solution Approach 1:
The system monitors the intensity of plasma emission and adjusts radio frequency power accordingly. By using the detected light intensity as feedback, the system optimizes RF power consumption to maintain sufficient plasma illumination for detection while minimizing energy waste
Solution Approach 2:
The system uses only the minimum necessary plasma emission intensity required for detection purposes. Rather than maintaining high plasma power continuously, the system adjusts RF power to provide just enough light emission for accurate measurement, reducing unnecessary energy consumption
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 method provides precise detection of substrate natural frequency and attraction state, reducing energy loss by controlling radio frequency power and enabling accurate assessment of warpage or deflection, while being cost-effective by integrating with existing plasma processing apparatus.
Implementation Method 1
detecting an amount of light reflected at the substrate by light emission of the plasma
Implementation Method 2
attracting the substrate onto the electrostatic chuck
Data Source
AI summary
A measuring method includes placing a substrate on an electrostatic chuck disposed inside a chamber, attracting the substrate onto the electrostatic chuck, generating plasma inside the chamber, detecting an amount of light reflected at the substrate by light emission of the plasma, and calculating a natural frequency of the substrate based on the amount of light.