Plasma Ignition Detection Using RGB Light Analysis
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Solution Overview
Problem
Existing plasma processing technologies face challenges in reliably detecting plasma ignition in a plasma generation region that is brightened by a heater's light, leading to difficulties in confirming whether plasma is generated or not, resulting in wasted processing time and operator burden.
Innovation Solution
A plasma processing apparatus and method that includes a light detection system to measure R, G, and B light intensities in the plasma generation region, calculates an evaluation value based on changes before and after high-frequency power is supplied to an antenna, and compares this value to a threshold to determine plasma ignition, ensuring reliable detection even when the region is brightened by a heater's light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the rotary table is made of light-transmitting material (quartz) to allow heater light to pass through, then the substrates can be heated effectively, but the plasma generation region remains bright even when plasma is not generated, making it difficult to confirm plasma ignition
Solution Approach 1:
The patent uses color component analysis (R, G, B) of the light detected from the plasma generation region to determine plasma ignition. By analyzing changes in color components before and after high-frequency power supply, the system can distinguish plasma emission from heater light transmission, solving the detection difficulty caused by the light-transmitting rotary table.
2Device complexity
If the worker manually confirms plasma ignition visually, then the system is simple, but the worker feels burdensome due to the inability to reliably distinguish plasma ignition from heater light
Solution Approach 1:
The patent replaces manual visual confirmation with an automated optical detection system that uses a light detector and color component analysis. This substitution eliminates the operator burden while maintaining system simplicity through software-based plasma ignition determination based on R, G, B light intensity changes.
3Productivity
If plasma ignition cannot be reliably detected, then the system operates continuously, but processing time is wasted when plasma is not actually generated
Solution Approach 1:
The patent implements a feedback mechanism where the light detection part continuously monitors the plasma generation region, the calculation part analyzes color component changes, and the ignition determination part uses this information to confirm plasma ignition status. This feedback loop ensures processing only continues when plasma is actually generated, preventing wasted processing time while maintaining productivity.
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 reliable detection of plasma ignition, preventing unnecessary processing and reducing operator burden by accurately determining plasma presence, thus optimizing processing efficiency.
Implementation Method 1
an antenna configured to generate an inductively coupled plasma by converting the process gas to plasma
Implementation Method 2
a light detection part configured to detect respective light intensities of an R component, a G component and a B component as light color components in a plasma generation region
Implementation Method 3
the light coming from a heater passes through the rotary table
Data Source
AI summary
There is provided an apparatus of performing a plasma process on substrates mounted on an upper surface of a rotary table. The apparatus includes: a heater for heating the substrates; a process gas supply part for supplying a process gas toward the upper surface of the rotary table; an antenna for generating an inductively coupled plasma by converting the process gas to plasma; a light detection part for detecting respective light intensities of R, G and B component as light color components; a calculation part for obtaining an evaluation value corresponding to a change amount before and after supplying a high-frequency power to the antenna, with respect to at least one of the respective light intensities; and an ignition determination part for comparing the evaluation value with a threshold value and to determine that ignition of plasma is not generated if the evaluation value does not exceed the threshold value.