Ultrasonic Cleaning Apparatus for Substrate Edge Face
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Solution Overview
Problem
Existing ultrasonic cleaning methods for disc-shaped substrates, such as semiconductor wafers and glass substrates, face challenges in efficiently cleaning edge faces due to limitations in the propagation distance of ultrasonic waves, leading to re-contamination and reduced cleaning effectiveness, as the cleaning liquid often becomes mist at longer distances and splashes back onto the substrate.
Innovation Solution
An ultrasonic cleaning apparatus that rotates the substrate to a horizontal position and sprays ultrasonic wave propagating water from a direction tangent to the edge face, using a flexible ultrasonic wave transmitting tube positioned above the substrate to control the spray angle and prevent re-contamination, allowing for efficient drainage of contaminated liquid without re-adherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the nozzle is moved closer to the substrate to maintain stable ultrasonic wave propagation, then the cleaning effectiveness is improved, but the device complexity and positioning precision requirements increase
Solution Approach 1:
The patent employs a rotating substrate table that allows the substrate to spin during cleaning. This dynamic motion ensures that the ultrasonic wave propagating water continuously contacts fresh areas of the edge face, maintaining cleaning effectiveness without requiring precise static positioning. The rotation compensates for the limited propagation distance by bringing different portions of the substrate edge into the effective cleaning zone sequentially.
Solution Approach 2:
The invention transitions from a static cleaning approach to a dynamic three-dimensional cleaning process by rotating the substrate. This adds a temporal and spatial dimension to the cleaning process, allowing the ultrasonic wave to effectively clean the entire edge face circumference through rotation, thereby reducing the need for multiple nozzles or complex positioning mechanisms.
2Area of stationary object
If ultrasonic wave propagating water is sprayed at a distance longer than 30mm, then the cleaning coverage is improved, but capillary waves are generated and the cleaning liquid becomes mist, reducing cleaning effectiveness
Solution Approach 1:
The rotating substrate enables effective cleaning of the entire edge face within the 30mm propagation distance limit. As the substrate rotates, different segments of the edge face pass through the ultrasonic water jet, ensuring complete coverage without requiring the nozzle to be positioned far from the substrate surface.
Solution Approach 2:
The periodic rotation of the substrate creates a cyclical cleaning pattern where each portion of the edge face is repeatedly exposed to the ultrasonic wave propagating water. This periodic action ensures thorough cleaning of the entire circumference while maintaining the nozzle within the effective propagation distance.
3Power
If the spot shower is positioned to spray vertically to the edge face, then the cleaning intensity is improved, but the cleaning liquid splashes back onto the substrate surface causing re-contamination
Solution Approach 1:
Instead of spraying vertically toward the center of the substrate, the ultrasonic wave propagating water is sprayed from the outer periphery toward the edge face in a tangential direction. This inverted spraying approach allows the cleaning liquid to flow off the edge face outward, preventing it from splashing back onto the substrate surface and causing re-contamination.
Solution Approach 2:
The cleaning process is localized to the edge face region only, with the ultrasonic wave propagating water applied specifically to the peripheral edge area. The spray direction and rotation work together to confine the cleaning action to the edge face, preventing contaminated liquid from reaching the substrate surface while maintaining high cleaning intensity at the target location.
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 approach enhances cleaning performance by improving separation strength and preventing re-contamination, with a high removal rate of particles and prevention of re-adherence, while allowing for flexible configuration and positioning of the cleaning apparatus.
Implementation Method 1
oscillating an ultrasonic transducer provided on a bottom of the cleaning bath
Implementation Method 2
cleaning liquid applied with an ultrasonic wave from a direction of a tangent line of an edge face is sprayed
Implementation Method 3
rotating a disc-shaped glass substrate with a main surface thereof extending perpendicularly and flowing cleaning liquid W irradiated with an ultrasonic wave on an outer peripheral edge face
Data Source
AI summary
An ultrasonic cleaning apparatus and an ultrasonic cleaning method for an edge face of a substrate help prevent re-contamination caused by splashing or the like of ultrasonic wave propagating water sprayed onto an edge face of an object to be cleaned. An ultrasonic wave transmitting tube provided to continue from the spot shower and configured to transmit and spray the ultrasonic wave propagating water to the substrate is provided, the ultrasonic wave transmitting tube is installed so as not to be positioned on the substrate, the substrate is retained so that the surface of the substrate assumes a horizontal state, and ultrasonic wave propagating water is sprayed to the edge face, which constitutes an outer periphery of the substrate arranged in a space from the ultrasonic wave transmitting tube in a direction of tangent line of the edge face while rotating the substrate by a rotatable rotation retaining portion.