Mega Sonic Wafer Cleaning Gap Control
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Solution Overview
Problem
Existing methods for cleaning semiconductor wafers using mega sonic energy face challenges in achieving uniform power density distribution, leading to inefficient particle removal and potential damage to the wafer structure due to non-uniform power application.
Innovation Solution
The method involves adjusting the gap between the mega sonic device and the rotating wafer by increments or decrements of half wavelengths for each rotation, controlled by a lead screw and motor system, to maintain consistent mega sonic power density across the wafer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mega sonic energy is applied to clean semiconductor wafers, then particle removal efficiency is improved, but uniform power density distribution is difficult to achieve leading to potential damage to wafer structure
Solution Approach 1:
The patent applies dynamics by making the gap between the mega sonic device and wafer variable rather than fixed. The gap is dynamically adjusted during the cleaning process to compensate for wafer rotation and maintain uniform power density distribution across the wafer surface, thereby resolving the contradiction between cleaning efficiency and power uniformity.
Solution Approach 2:
The patent changes the physical parameter of the gap distance between the mega sonic device and wafer. By adjusting this parameter dynamically during operation, the system maintains optimal power density distribution while preserving high particle removal efficiency, thus resolving the technical contradiction.
2Productivity
If mega sonic power is increased to remove particles efficiently, then cleaning effectiveness is improved, but damage to device structure on wafer increases
Solution Approach 1:
The patent applies local quality by ensuring that different regions of the wafer receive appropriate mega sonic power levels. By dynamically adjusting the gap, the system provides higher power where needed for particle removal while limiting power in sensitive areas, thus achieving effective cleaning without excessive damage to device structures.
Solution Approach 2:
The dynamic adjustment of the gap allows the system to modulate power delivery in real-time, applying higher power for particle removal when needed while reducing power exposure to protect sensitive device structures, thereby resolving the contradiction between cleaning effectiveness and structural damage.
3Device complexity
If fixed gap between mega sonic device and wafer is used, then device complexity is reduced, but uniform power distribution cannot be maintained during wafer rotation
Solution Approach 1:
The patent introduces dynamic gap adjustment mechanisms that actively modify the gap distance during wafer rotation. This dynamic approach maintains uniform power density distribution across the rotating wafer surface, resolving the contradiction between device simplicity and power uniformity by making the system adaptively complex only when necessary.
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 ensures uniform mega sonic power distribution, enhancing the efficiency of particle removal while minimizing damage to the wafer structure by ensuring each portion receives a full cycle of power density, maintaining consistent average, maximum, and minimum power densities.
Implementation Method 1
Mega sonic energy coupled with nozzle to clean semiconductor wafer is disclosed in U.S. Pat. No. 4,326,553. The fluid is pressurized and mega sonic energy is applied to the fluid by a mega sonic transducer.
Implementation Method 2
A source of energy vibrates an elongated probe which transmits the acoustic energy into the fluid is disclosed in U.S. Pat. No. 6,039,059.
Data Source
AI summary
A method for cleaning semiconductor substrate using ultra/mega sonic device comprising holding a semiconductor substrate by using a chuck, positioning a ultra/mega sonic device adjacent to the semiconductor substrate, injecting chemical liquid on the semiconductor substrate and gap between the semiconductor substrate and the ultra/mega sonic device, changing gap between the semiconductor substrate and the ultra/mega sonic device for each rotation of the chuck during the cleaning process. The gap can be increased or reduced by 0.5/N for each rotation of the chuck, where λ is wavelength of ultra/mega sonic wave, N is an integer number between 2 and 1000. The gap is varied in the range of 0.5λn during the cleaning process, where λ is wavelength of ultra/mega sonic wave, and n is an integer number starting from 1.