Megasonic cleaning is a specialized cleaning method that utilizes

high-frequency High frequency (HF) is the International Telecommunication Union, ITU designation for the radio band, band of radio waves with frequency between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengt ...

sound waves In physics, sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the br ...

to remove

contaminants Contamination is the presence of a constituent, impurity, or some other undesirable element that renders something unsuitable, unfit or harmful for the physical body, natural environment, workplace, etc. Types of contamination Within the scie ...

from delicate surfaces. It is particularly effective in industries like

semiconductor manufacturing Semiconductor device fabrication is the process used to manufacture semiconductor devices, typically integrated circuits (ICs) such as microprocessors, microcontrollers, and memories (such as Random-access memory, RAM and flash memory). It is a ...

optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of optical instruments, instruments that use or Photodetector, detect it. Optics usually describes t ...

, and

medical device A medical device is any device intended to be used for medical purposes. Significant potential for hazards are inherent when using a device for medical purposes and thus medical devices must be proved safe and effective with reasonable assura ...

production, where precision and gentle cleaning are crucial. It is a type of

acoustic cleaning Acoustic cleaning is a maintenance method used in material-handling and storage systems that handle bulk granular or particulate materials, such as grain elevators, to remove the buildup of material on surfaces. An acoustic cleaning apparatus, ...

related to

ultrasonic cleaning Ultrasonic cleaning is a process that uses ultrasound (usually from 20 to 40 kHz) to agitate a fluid, with a cleaning effect. Ultrasonic cleaners come in a variety of sizes, from small desktop units with an internal volume of less than , to large ...

. Similar to

, megasonic cleaning uses a

transducer A transducer is a device that Energy transformation, converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another. Transducers are often employed at the boundaries of automation, M ...

that sits on top of a

piezoelectric Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied stress (mechanics), mechanical s ...

substrate. The transducer creates acoustic waves at a higher

frequency Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...

(typically 0.8–2

MHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base u ...

) than ultrasonic cleaning (20-200

kHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base uni ...

). As a result, the

cavitation Cavitation in fluid mechanics and engineering normally is the phenomenon in which the static pressure of a liquid reduces to below the liquid's vapor pressure, leading to the formation of small vapor-filled cavities in the liquid. When sub ...

that occurs is reduced and on a much smaller scale.

Comparison to ultrasonic cleaning

Megasonic cleaning differs from

in the

that is used to generate the acoustic waves. Ultrasonic cleaning uses lower frequencies and its mechanism relies on

, while megasonic cleaning uses higher frequencies and produces less damaging cavitation. In ultrasonic devices, cavitation occurs throughout the tank, and all sides of submerged parts are cleaned. In megasonic devices, the

acoustic wave Acoustic waves are types of waves that propagate through matter—such as gas, liquid, and/or solids—by causing the particles of the medium to compress and expand. These waves carry energy and are characterized by properties like acoustic pres ...

is found only in a line of sight from the

surface. For this reason, megasonic

transducers A transducer is a device that converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another. Transducers are often employed at the boundaries of automation, measurement, and contro ...

are typically built using arrays of closely spaced square or rectangular

devices that are bonded to a substrate.

Semiconductor A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities (" doping") to its crystal structure. When two regions with different doping level ...

wafers are typically cleaned in carriers holding the substrates perpendicular to the

, allowing both the front and back surfaces to be cleaned. Special carriers are sometimes used to reduce any obstructions that may prevent parts of the wafer surface from being cleaned. Megasonic cleaners come in many configurations, such as single or dual nozzle systems, or single-wafer transducers. In single-wafer devices, the wafer rotates on a spinning tool, and the megasonic waves are applied from above.

References

{{Reflist Ultrasound Cleaning methods

Comparison to ultrasonic cleaning

See also

References