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As the name suggests, megasonics are ultra-high-frequency ultrasonic waves, so megasonic cleaning is a type of ultra-high-frequency ultrasonic cleaning. Like ultrasonic cleaning, a megasonic cleaner utilizes a transducer to convert high-power sonic energy into mechanical vibrations, radiating ultrasonic waves into the cleaning solution. The tiny bubbles in the liquid vibrate under the influence of the megasonic waves, breaking the adhesion of contaminants to the surface of the substrate (the item being cleaned), causing the contaminant layer to fatigue and peel away, thereby achieving the cleaning objective. This application primarily leverages the cavitation effect of ultrasonics. Megasonic cleaning uses an even higher frequency, at the ultra-high-frequency level of megahertz. Compared to the cavitation effect of low-frequency ultrasonics, megasonic cavitation can remove smaller particles and significantly reduce damage to the substrate.
Figure 1. The wafer
Traditional megasonic cleaning system includes shower type megasonic cleaning system and batch type megasonic cleaning system. The advantage of shower type megasonic cleaning system is that it can focus the megasonic energy directly onto the substrate surface, resulting in a higher energy transfer efficiency. However, since the shower type radiating area is relatively small, the cleaning speed is slower, and it requires a larger cleaning solution flow rate, leading to a more significant waste of cleaning solution. The advantage of batch type megasonic cleaning system is that the megasonic transducer has a larger area, allowing for a broader radiating sound field and higher cleaning efficiency. However, the downside is that the distribution of the megasonic sound field in the water tank is uneven, with the sound intensity weakening as the distance from the transducer increases, and a lower energy transfer efficiency.
Figure 2. The cover type megasonic cleaning system from Siansonic Technology
Cover-type megasonic cleaning system, based on shower-type meagsonic cleaning system and batch-type megasonic cleaning system, offers a more optimized solution: it transfers megasonic energy evenly across a relatively large area directly to the substrate surface, resulting in a very high transfer efficiency and uniform sound field. This not only improves cleaning efficiency but also significantly reduces the waste of cleaning solutions, making it more suitable for cleaning flat substrates such as semiconductor wafers cleaning.
The convert type megasonic cleaning system from Sianosnic Technology uses a third-generation semiconductor technology megasonic wave generator, fully implementing digital high-frequency high-power driving. The convert-type megasonic cleaning system as a whole uses non-metallic, highly corrosion-resistant materials, suitable for various acidic, alkaline, and organic solvent cleaning processes, making it more applicable to wafer cleaning in the semiconductor field.