Monolithic Crystalline Phosphor Sensor for Plasma Chamber
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current fiber optic temperature sensors are infeasible for in-chamber operation in plasma processing chambers due to harsh environments, which limits their ability to accurately measure temperatures of individual components, especially at very low temperatures, and may contaminate the process with ionic contaminants.
Innovation Solution
A plasma processing chamber optical temperature sensor design featuring a monolithic crystalline phosphor element thermally coupled to a plasma processing chamber component, using a light source and light detector with a light pipe for transmission, and mechanical bonding methods like O-rings or retention rings for durability and chemical resistance, eliminating the need for adhesives and encapsulation materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fiber optic temperature sensors use silicone, epoxy, or inorganic ceramic adhesives, then the sensor can be manufactured and assembled, but the adhesives may degrade upon exposure to the plasma processing chamber environment or contaminate the process with ionic contaminants
Solution Approach 1:
The patent removes adhesives and encapsulation materials from the sensor construction, eliminating the source of ionic contamination. The optical temperature sensing element is directly mounted to the plasma processing chamber component using mechanical means such as O-rings or retention rings, which are chemically inert and do not degrade in the plasma environment.
Solution Approach 2:
The patent applies different material properties to different parts of the sensor system. The optical temperature sensing element and mounting components (O-rings, retention rings) are made from materials specifically selected for their chemical inertness and resistance to plasma environment, while avoiding materials that would contaminate the process.
2Reliability
If fiber optic temperature sensors are positioned outside the plasma processing chamber, then the sensor components are protected from harsh environment, but measuring temperatures of individual plasma processing chamber components becomes difficult or impossible
Solution Approach 1:
The patent divides the sensor system into two parts: the optical temperature sensing element that is directly mounted within the plasma processing chamber for accurate component temperature measurement, and the light source and light detector that remain outside the chamber. This segmentation allows the sensing element to be exposed to the plasma environment while protecting the electronic components.
Solution Approach 2:
The patent uses a light pipe as an intermediary to transmit light from the light source outside the chamber through the chamber wall to the optical temperature sensing element inside the chamber, and to carry the emitted light back to the light detector. This allows the sensing element to be positioned within the chamber for accurate measurement while keeping the light source and detector outside for protection.
3Measurement precision
If pyrometers are used for remote in-chamber temperature monitoring, then temperature measurement can be performed, but variable emissivity of components and chemical coatings presents significant challenges
Solution Approach 1:
The patent replaces the pyrometer-based remote optical measurement system with a direct contact thermal coupling system. The optical temperature sensing element is thermally coupled to the plasma processing chamber component through direct contact or embedding, eliminating the need to account for emissivity variations and chemical coatings that affect pyrometer readings.
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 accurate, durable, and chemically resistant temperature measurement of plasma processing chamber components within the harsh environment, reducing process contamination and improving temperature sensing accuracy by shielding from stray light.
Implementation Method 1
a monolithic crystalline phosphor element configured to be excited by light from the light source transmitted via the light pipe and emit light back via the light pipe to the light detector indicative of a temperature of the monolithic crystalline phosphor element
Implementation Method 2
An optical temperature sensing element may be thermally coupled to and embedded in a plasma processing chamber component within the plasma processing chamber
Data Source
AI summary
A plasma processing chamber optical temperature sensor is disclosed. The plasma processing chamber optical temperature sensor includes a light source, a light detector, and a means for transmitting light through a wall of a plasma processing chamber. An optical temperature sensing element is thermally coupled to a plasma processing chamber component within the plasma processing chamber. The optical temperature sensing element includes a monolithic crystalline phosphor element configured to be excited by light from the light source and to emit light back to the light detector indicative of a temperature of the monolithic crystalline phosphor element.