Ultrasonic Substrate Cleaning With Variable Liquid Supply
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Solution Overview
Problem
Ultrasonic cleaning methods often result in uneven particle removal efficiency across a substrate due to interference from holding members and varying ultrasonic wave radiation, leading to lower cleaning efficiency in certain areas.
Innovation Solution
A substrate cleaning method and system that generates ultrasonic waves in a cleaning liquid while varying the supply rate of the cleaning liquid, including both continuous and intermittent supply modes, to uniformly remove particles from the substrate by controlling the ultrasonic wave generation and liquid supply in a cleaning tank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ultrasonic waves are radiated from below a substrate to be processed, then the cleaning process is simple and efficient, but particle removing efficiency becomes uneven across different areas of the substrate
Solution Approach 1:
The patent applies local quality by varying the cleaning liquid supply rate to different areas or at different times during ultrasonic cleaning. By adjusting the supply rate dynamically, the system creates locally optimized cleaning conditions that compensate for the uneven ultrasonic wave distribution caused by the holding member, thereby achieving uniform particle removal across the entire substrate surface.
Solution Approach 2:
The patent implements dynamics by continuously or intermittently adjusting the cleaning liquid supply rate during the ultrasonic cleaning process. This dynamic adjustment allows the system to adapt to changing cleaning conditions and maintain optimal particle removal efficiency across different substrate areas, transforming a static cleaning process into a dynamically controlled one.
2Reliability
If a holding member is used to hold the substrate from below, then the substrate can be securely positioned, but the holding member interferes with ultrasonic wave radiation and reduces cleaning efficiency in certain areas
Solution Approach 1:
The patent applies parameter changes by adjusting the cleaning liquid supply rate as a controllable parameter to compensate for the interference caused by the holding member. By changing the supply rate parameter dynamically, the system maintains reliable substrate positioning while overcoming the negative impact on particle removal efficiency in shadowed areas.
Solution Approach 2:
The cleaning liquid acts as an intermediary that transmits ultrasonic energy more effectively to areas shadowed by the holding member. By optimizing the liquid supply rate, the system enhances the mediator's ability to carry ultrasonic waves to all substrate surfaces, thereby maintaining positioning stability while improving overall cleaning efficiency.
3Ease of operation
If cleaning liquid is supplied continuously at a constant rate during ultrasonic wave generation, then the cleaning process is simple to control, but particle removal uniformity across the substrate surface is poor
Solution Approach 1:
The patent transforms the static, constant supply rate into a dynamic, variable supply rate that changes during the ultrasonic cleaning process. This dynamic control maintains relative simplicity in operation while significantly improving particle removal uniformity by adapting the supply rate to the specific cleaning needs of different substrate areas or time periods.
Solution Approach 2:
The patent implements periodic action by using intermittent or cyclic variations in the cleaning liquid supply rate during ultrasonic wave generation. This periodic adjustment creates alternating phases of different supply rates that enhance particle removal uniformity across the substrate while maintaining straightforward control through programmed cycles.
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 the overall particle removal efficiency by adjusting the cleaning liquid supply rate and ultrasonic wave generation to address uneven cleaning areas, ensuring more uniform particle removal across the substrate.
Implementation Method 1
generating ultrasonic waves in the cleaning liquid
Implementation Method 2
generating ultrasonic waves in the cleaning liquid contained in the cleaning tank
Data Source
AI summary
The present invention provides a substrate cleaning method capable of removing particles from the entire surface of a substrate to be processed at a high removing efficiency. In the substrate cleaning method according to the present invention, a substrate to be processed W is immersed in a cleaning liquid in a cleaning tank 12. Then, ultrasonic waves are generated in the cleaning liquid contained in the cleaning tank 12, so that the substrate W is subjected to an ultrasonic cleaning process. The step of generating ultrasonic waves includes a step of generating ultrasonic waves in the cleaning tank while the cleaning liquid is being supplied into the cleaning tank. A supply rate at which the cleaning liquid is supplied into the cleaning tank at a certain timing in the step of generating ultrasonic waves differs from a supply rate at which the cleaning liquid is supplied into the cleaning tank at another timing in the step of generating ultrasonic waves.