Optical Window Purge Flow for Stable Wafer Temperature Sensing
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Solution Overview
Problem
Contaminants from the process gas accumulate on the optical window of a radiation thermometer, making it difficult to perform highly reproducible temperature measurements in substrate processing apparatuses.
Innovation Solution
A substrate processing apparatus with a port that provides an optical path, an optical window mounted airtight, a purge gas supplier, and a partition to guide purge gas to the optical window, preventing contamination and maintaining stable temperature measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the radiation thermometer measures temperature through the optical window, then temperature measurement is enabled, but contaminants accumulate on the optical window making measurements unreproducible
Solution Approach 1:
A purge gas flow is introduced as an intermediary between the process gas and the optical window. The purge gas flows along the inner surface of the optical window, creating a protective barrier that prevents contaminants from the process gas from accumulating on the window surface, thereby maintaining measurement reproducibility
Solution Approach 2:
An inert purge gas (such as nitrogen or argon) is supplied to create an inert atmosphere around the optical window. This inert environment prevents reactive contaminants from the process gas from depositing on the optical window surface, ensuring stable and reproducible temperature measurements over time
2Measurement precision
If the optical window is exposed inside the process chamber, then temperature measurement is possible, but the optical window temperature rises due to heat from the process chamber
Solution Approach 1:
The purge gas acts as a thermal intermediary, flowing between the hot process chamber and the optical window. This gas flow provides thermal isolation by carrying heat away from the optical window surface, preventing excessive temperature rise that would affect measurement accuracy and window integrity
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
Stable temperature measurements are achieved by suppressing contamination and temperature rise of the optical window, ensuring high reproducibility and reducing maintenance frequency.
Implementation Method 1
the internal temperature of the process chamber is measured based on radiation light from the interior of the process chamber that is incident through an optical window
Implementation Method 2
a purge gas supplier that is disposed inside the process container and supplies a purge gas to an inner surface of the optical window
Data Source
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AI summary
There is provided a configuration that includes at least one port that is provided in a process container in which a substrate is accommodated and heat-treated, the port providing an optical path that penetrates an interior of the process container and an exterior of the process container; an optical window that is mounted to the port and transmits light while maintaining the port airtight; a purge gas supplier that is disposed inside the process container and provides a purge gas to an inner surface of the optical window; and a partition that guides the purge gas from the purge gas supplier to the optical window.