Laser-Roughened SiC Wafer Contact Surface for Vacuum Clamping
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Solution Overview
Problem
Existing ceramic devices used in semiconductor processing systems face challenges in achieving a controlled surface roughness for efficient wafer handling, as smooth surfaces can lead to sticking issues while excessively rough surfaces result in vacuum leaks and premature wear.
Innovation Solution
A method utilizing a defocused laser beam to create a controlled roughness on ceramic substrates, specifically reaction-bonded silicon carbide surfaces, which are then machined to maintain the desired roughness for wafer contact, preventing sticking and ensuring adequate vacuum clamping without leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ceramic surface is made smooth, then vacuum clamping is improved, but wafer sticking occurs
Solution Approach 1:
The patent applies local quality by creating a non-uniform surface structure on the ceramic wafer contact surface. A controlled roughness layer is formed through laser treatment, where the surface topology varies at different scales: micro-scale peaks and valleys provide vacuum sealing, while macro-scale smooth zones prevent sticking. This local variation in surface quality resolves the contradiction between needing smoothness for vacuum clamping and roughness for preventing sticking.
2Object-generated harmful factors
If the ceramic surface is made rough, then wafer sticking is prevented, but vacuum leaks occur
Solution Approach 1:
The controlled roughness structure creates local quality variations where valleys provide vacuum sealing while peaks prevent sticking. The hierarchical surface topology ensures that at the micro-scale, the surface features are rough enough to prevent wafer adhesion, but at the macro-scale, sufficient smooth areas remain to maintain vacuum integrity and prevent leaks.
3Object-generated harmful factors
If the ceramic surface is made rough, then wafer sticking is prevented, but wear increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the roughness parameters through laser treatment. The surface roughness is optimized to a specific range that prevents wafer sticking while minimizing wear. The controlled roughness structure creates a tribological interface with optimized friction and wear characteristics, extending device life while preventing sticking.
4Productivity
If a focused laser beam is used, then material removal is efficient, but surface roughness control is lost
Solution Approach 1:
The patent inverts the conventional laser focusing approach by using a defocused laser beam. Instead of concentrating energy at a single point for maximum material removal efficiency, the laser is deliberately defocused to create a broader, more uniform energy distribution. This produces the desired controlled roughness pattern across the surface while maintaining acceptable material removal rates, resolving the contradiction between efficiency and precision.
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 controlled roughness enhances the durability and effectiveness of wafer handling by preventing sticking and vacuum leaks, maintaining a consistent tribological interface and extending the device's useful life with reduced wear.
Implementation Method 1
using a defocused laser beam to roughen a surface of a ceramic substrate
Implementation Method 2
A method utilizing a defocused laser beam to create a controlled roughness on ceramic substrates
Data Source
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AI summary
A method of making a ceramic device with a controlled roughness includes using a defocused laser beam to roughen a surface of a ceramic substrate, and removing one or more portions of the roughened surface without removing all of the roughened surface. If desired, the ceramic device may include reaction-bonded silicon carbide, and an opening may be formed in the device so that the device can be used to apply a clamping suction to a wafer surface. A ceramic surface with a controlled roughness is also disclosed. The defocused laser beam may be used to make the surface rough enough to prevent it from sticking to a mating element, and to have adequate wear resistance, but not so rough as to prevent the formation of sufficient suction to clamp the surface to a mating element.