Electrostatic Chuck Edge Ring with Lanthanoid for UV Monitoring
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Solution Overview
Problem
Monitoring of ultraviolet rays in the vacuum ultraviolet region during plasma etching processes is challenging due to their absorption by chamber materials and inability to pass through typical chamber windows, making it difficult to detect harmful radiation effects on wafers.
Innovation Solution
Incorporating a lanthanoid element, such as cerium, in the edge ring of an electrostatic chuck, which emits visible light when irradiated with ultraviolet rays, allowing for the detection of ultraviolet radiation through photoluminescence, even in regions not visible through standard chamber windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a chamber window made of quartz glass or Pyrex glass is used to monitor plasma state, then visible light transmission is enabled, but vacuum ultraviolet radiation cannot pass through the window
Solution Approach 1:
The patent introduces a fluorescent substance as an intermediary that absorbs vacuum ultraviolet radiation and converts it to visible light. This fluorescent substance is positioned in the chamber where vacuum ultraviolet is generated, and it mediates the conversion between the two types of radiation, allowing indirect detection of vacuum ultraviolet through visible light transmission through the chamber window
Solution Approach 2:
The patent replaces direct vacuum ultraviolet detection (which requires special windows or direct chamber access) with optical detection of visible light emitted by the fluorescent substance. This substitution allows using standard optical sensors and chamber windows, simplifying the detection system while enabling vacuum ultraviolet monitoring
2Measurement precision
If electromagnetic waves in vacuum ultraviolet region are directly measured, then accurate plasma state monitoring is achieved, but the measurement cannot be performed in atmosphere due to absorption by oxygen and nitrogen molecules
Solution Approach 1:
The patent performs the vacuum ultraviolet to visible light conversion in advance within the vacuum environment where vacuum ultraviolet is generated. The fluorescent substance converts the radiation before it encounters atmospheric gases, eliminating the problem of atmospheric absorption and enabling subsequent visible light detection in air
3Loss of information
If vacuum ultraviolet radiation is directly observed from outside the chamber, then harmful radiation effects on wafers can be monitored, but the chamber window material absorbs the vacuum ultraviolet waves
Solution Approach 1:
The patent changes the wavelength parameter of the radiation being transmitted through the chamber window. By converting vacuum ultraviolet radiation to visible light using the fluorescent substance, the radiation parameter changes from a wavelength range that is absorbed by the window material to one that can pass through, enabling information transmission without requiring changes to the chamber window
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 the monitoring of ultraviolet radiation generation situations during semiconductor manufacturing processes, including plasma etching, by converting ultraviolet rays into visible light that can be detected externally, thereby addressing the limitations of existing monitoring methods.
Implementation Method 1
a lanthanoid element is included in a part of a material of the member, and wherein when electromagnetic waves in a wavelength region shorter than 400 nm are irradiated, the member emits light in a wavelength region different from the wavelength region of the electromagnetic waves
Data Source
AI summary
A lanthanoid element is included in a part of a material of a member for an electrostatic chuck configured to suck a target object by using an electrostatic force. When electromagnetic waves in a wavelength region shorter than 400 nm are irradiated, the member emits light in a wavelength region different from the wavelength region.