Plasma Processing Temperature Measurement via Sealed Windows
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Solution Overview
Problem
In plasma processing apparatuses, accurate temperature measurement of substrates is hindered by pressure differences and air flow affecting the optical path, leading to measurement inaccuracies due to substrate mounting table deformation and vibration.
Innovation Solution
A plasma processing apparatus with airtightly sealed temperature measuring windows and connection members between the mounting table and base plate, maintaining a vacuum atmosphere above and normal pressure below, along with collimators fixed to the base plate, allows for precise temperature measurement through optical communication via these windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mounting table is maintained under pressure difference between vacuum and atmospheric pressure, then the substrate can be processed in vacuum atmosphere, but the mounting table bends or vibrates causing distance changes between collimator and substrate
Solution Approach 1:
Airtightly sealed temperature measuring windows are introduced as intermediary structures that allow optical beams to pass through the mounting table while maintaining the pressure difference. These windows create sealed measurement spaces that isolate the optical path from the atmospheric pressure effects, enabling temperature measurement without compromising vacuum atmosphere maintenance.
Solution Approach 2:
The mounting table is segmented into multiple regions: vacuum processing regions above the table, atmospheric regions below the table, and sealed measurement spaces containing the temperature measuring windows. This segmentation allows different pressure environments to coexist while enabling optical access for temperature measurement through the sealed windows.
2Ease of manufacture
If collimators are fixed outside the vacuum chamber for easy maintenance, then maintenance convenience is improved, but the optical path is affected by air flow causing measurement accuracy deterioration
Solution Approach 1:
Temperature measuring windows serve as intermediary structures that extend the optical measurement path from the vacuum environment through the mounting table to the atmospheric environment. This allows collimators to be positioned in the atmospheric region for easy maintenance while the measurement space within the window remains isolated from air flow effects.
Solution Approach 2:
The measurement system transitions from a purely vacuum-based optical path to a multi-dimensional path that passes through sealed windows in the mounting table. This dimensional transition allows the optical path to traverse from the vacuum region through the table structure to the atmospheric region, enabling collimator placement outside the vacuum chamber.
3Adaptability or versatility
If the space between mounting table and base plate is used for RF plate insulation and pusher pin installation, then functional requirements are met, but the atmospheric space affects the optical path through air flow
Solution Approach 1:
The space between the mounting table and base plate is segmented into functionally distinct regions: atmospheric regions for RF plate insulation and pusher pin installation, and sealed vacuum regions for substrate processing. Temperature measuring windows are positioned to access only the vacuum regions, isolating the optical path from atmospheric interference while preserving functional versatility.
Solution Approach 2:
Different regions of the mounting table structure are assigned different pressure environments based on local functional requirements. Vacuum regions are maintained for substrate processing areas, while atmospheric regions are provided for support functions. Sealed temperature measuring windows are strategically positioned to access only vacuum regions, ensuring optical path stability.
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 configuration enables high-accuracy temperature control and efficient plasma processing by stabilizing the optical path and reducing noise from air flow and substrate deformation, enhancing measurement precision.
Implementation Method 1
an interference wave of reflected n measurement beams from the target and a reflected reference beam from the reference beam reflector is measured by a light receiving unit
Implementation Method 2
optical fibers for irradiating the measurement beam onto the substrate
Data Source
AI summary
A plasma processing apparatus includes a temperature measuring unit; airtightly sealed temperature measuring windows provided in a mounting table, for optically communicating to transmit a measurement beam through a top surface and a bottom surface of the mounting table; and one or more connection members for connecting the mounting table and a base plate, which is provided in a space between the mounting table and the base plate. In the plasma processing apparatus, a space above the mounting table is set to be maintained under a vacuum atmosphere, and a space between the mounting table and the base plate is set to be maintained under a normal pressure atmosphere, and each collimator is fixed to the base plate at a position corresponding to each temperature measuring window, thereby measuring a temperature of the substrate via the temperature measuring windows by the temperature measuring unit.