Concentric SiC Lightpipe for High-Temperature Substrate Processing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lightpipe designs for high-temperature semiconductor processing face challenges in maintaining concentricity, leading to non-uniform purging and surface contamination, which shortens the lifetime of the lightpipe and affects temperature measurement accuracy.
Innovation Solution
A concentric lightpipe design with a high-resistivity silicon carbide (SiC) sheath formed by chemical vapor deposition, featuring local protrusions to center the sapphire core and ensure proper positioning, allowing for uniform purging and reducing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional lightpipe design is used, then the lightpipe can be inserted through a small hole for temperature measurement, but the lightpipe surfaces become contaminated due to non-uniform purging, shortening its lifetime
Solution Approach 1:
The lightpipe structure is segmented into a core and a surrounding sheath, allowing independent optimization of each component. The sheath can be specifically designed with purging capabilities while the core maintains optical properties, resolving the contradiction between measurement function and contamination resistance
Solution Approach 2:
A sheath is introduced as an intermediary component between the lightpipe core and the contaminated environment. This sheath acts as a protective barrier that enables uniform purging of the lightpipe surfaces, preventing contamination while maintaining the core's temperature measurement function
2Measurement precision
If the lightpipe tip is positioned close to the target for better measurement, then temperature measurement accuracy improves, but the lightpipe is more susceptible to contamination from deposition processes
Solution Approach 1:
The sheath serves as an intermediary protective layer that shields the lightpipe core from harmful deposition processes. It enables the lightpipe to operate close to the target for accurate measurement while the sheath's purging system prevents contamination
Solution Approach 2:
The sheath creates a protected environment around the lightpipe core, allowing inert gas purging to maintain a clean atmosphere at the lightpipe tip. This enables close proximity operation without contamination from the deposition environment
3Ease of manufacture
If concentricity is not properly controlled, then the manufacturing process is simpler, but the purging flow becomes non-uniform, causing localized surface contamination
Solution Approach 1:
The segmentation into core and sheath allows the sheath to be designed with built-in concentricity features (such as dimples) that ensure uniform purging flow. This structural segmentation resolves the contradiction by making concentricity control an inherent part of the sheath design rather than a separate manufacturing challenge
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
The concentric design enhances the longevity and accuracy of temperature measurements by maintaining a clean and uniformly purged lightpipe surface, even in extreme high-temperature environments.
Implementation Method 1
The sheath is formed by a chemical vapor deposition process
Implementation Method 2
optical pyrometers measure temperature based upon electromagnetic radiation (light) the is emitted from the object (wafer)
Implementation Method 3
optical pyrometers measure temperature based upon electromagnetic radiation (light) the is emitted from the object (wafer)
Data Source
AI summary
A substrate processing system in accordance with one embodiment includes a processing chamber and an optical pyrometer assembly to measure an emitted thermal radiation originating substantially from a portion of target surfaces. The optical pyrometer includes a lightpipe that comprises a core and a hollow sheath surrounding the core. The core and the sheath are concentric with one another. The sheath is formed by a chemical vapor deposition process and includes local protrusions within a hollow interior thereof to maintain a position of the core within the sheath. In particular, the local protrusions are formed so as to center at least a distal end portion of the core within the sheath. A temperature of the target surface is determined from an intensity of a portion of the emitted thermal radiation near at least one wavelength.