Traditional silicon wafer cleaning uses aggressive chemicals to strip wafers and remove particles during semiconductor manufacturing. As semiconductor components such as processors, switches and memory chips become more tightly packed, removing all traces of contamination on the wafer surface becomes important for the production of high quality components and the reduction of component failure rates. Even sub micron particles can block the formation of a conducting path or a key structural component. Ensuring the removal of sub micron particles with traditional cleaning and rinsing has become challenging. Megasonic cleaning can remove even the tiniest particles from silicon wafers and improve process reliability.
How Megasonic Cleaning Works
Cleaning parts with megasonic sound waves in a cleaning solution is a quick and effective way of removing contamination from part surfaces. This cleaning method uses a range of high frequencies with the lower end used for less fragile pieces. The highest frequencies are used for the most delicate parts or parts with soft surfaces.
The sound waves in the cleaning solution create microscopic cavitation bubbles in the wave pressure troughs and the bubbles collapse in the wave peaks. When a bubble collapses, it emits a tiny but energetic jet of cleaning solution that dislodges contaminants and particles from part surfaces. Lower frequencies create comparatively large bubbles with stronger jets while the higher frequencies produce cleaning action with smaller bubbles and lower jet energy.
Because semiconductor components often include very delicate structures and soft layers of deposits on the silicon, only the highest frequencies deliver cleaning gentle enough to avoid structural damage and pitting. Megasonic cleaning takes place with frequencies around the 1 MHz level and higher and delivers effective cleaning without damage. The cleaning method is especially good at dislodging and removing particles as small as 0.1 microns with tiny bubbles breaking the particle’s adhesion to the underlying silicon wafer.
Modutek’s Megasonic Cleaning Solution
Modutek has partnered with Kaijo Shibuya Corporation, a world leader in Megasonic and ultrasonic cleaning technology, to create a line of Megasonic cleaning equipment suitable for use in semiconductor manufacturing. Megasonic cleaning systems can either be turn-key and integrated in fully automated wet bench station, or supplied as individual Megasonic generators and transducers.
Turnkey systems include the cleaning tank with the transducers already mounted while individual components can be integrated in existing semiconductor manufacturing lines. Equipment such as the Spot Shower, Mega Puck and Mega Tube allow operators to direct the Megasonic cleaning action to specific areas in the cleaning tank or on the surfaces of the silicon wafers. Megasonic cleaning reduces sub micron particle counts and can help produce better manufacturing results.
Modutek Megasonic Cleaning Features and Benefits
Systems using high frequency sound waves to clean silicon wafers have to be able to function at several frequencies, depending on the fragility of the parts to be cleaned. At the selected frequency, the megasonic transducers have to deliver enough power to fill the cleaning tank with sound waves, ensuring equal and consistent cleaning without dead spots. Ideally the bath and the transducers should be able to operate at elevated temperatures because some semiconductor manufacturing processes may use heated baths.
Modutek’s Megasonic cleaning systems operate at 950 kHz but frequencies between 200 kHz and 2 MHz are also available. High efficiency generators and full-power transducers deliver up to 1200 W of cleaning power and the systems can operate with bath temperatures of up to 140 degrees centigrade. These features deliver unparalleled cleaning performance without pitting or damage to silicon micro structures. The superior removal rate for particles down to 0.1 microns increases semiconductor component yields, reduces the number of defective components and improves product quality. For a free consultation or quote contact Modutek at 866-803-1533 or email [email protected].
For small operations and specialized applications requiring semiconductor fabrication capabilities it often doesn’t make sense to construct wet processing lines that produce products at volume. Table top process tanks can allow research labs, universities and start-up companies to produce single parts or low-volume output. These organizations may need proof of concept components or prototypes for testing. Small chemical process tanks deliver the capability to fabricate such products in a customized unit designed for the specialized applications.