Silicon Wafers Ultra-Sonic Cleaning Process

university wafer substrates

How Do Researchers Used Silicon Wafers For Ultrasonic Cleaning Processes?

Researchers at an international university have used silicon wafers from to develope and transport many processes in photolithography and physical vapor deposition techniques to production line while the establishinghe first serial production photolithography line for the optics industry. Developing ultrasonic cleaning processes for different kind of products, developing the effective use of industrial adhesives.

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What is Ultrasonic Cleaning?

Ultrasonic cleaning is a process that uses high-frequency sound waves (typically between 20 and 400 kHz) to clean materials and surfaces. The sound waves create microscopic bubbles in a liquid cleaning solution, which then collapse rapidly, generating high-pressure shock waves. These shock waves create a scrubbing action that effectively removes contaminants such as dirt, grease, oils, and other residues from surfaces.

Ultrasonic cleaning is commonly used in industrial, medical, and laboratory settings to clean a wide range of items, including jewelry, electronic parts, medical instruments, and even car parts. It is often preferred over other cleaning methods because it is non-abrasive, non-corrosive, and can clean intricate and hard-to-reach areas. Additionally, ultrasonic cleaning is an environmentally friendly process as it typically uses water-based cleaning solutions and does not generate hazardous waste.

How are Silicon Wafers Used?

Silicon wafers are used in a wide variety of electronic applications. Here are some of the most common uses of silicon wafers:
  1. Semiconductor manufacturing: Silicon wafers are the foundation for creating integrated circuits (ICs), which are the building blocks for most electronic devices, including smartphones, computers, and televisions.

  2. Solar panel manufacturing: Silicon wafers are also used in the production of solar panels. They serve as the base material for the photovoltaic cells that convert sunlight into electricity.

  3. MEMS devices: Silicon wafers are also used in the manufacturing of micro-electromechanical systems (MEMS). MEMS devices are tiny mechanical systems that can sense, actuate, and control a wide range of physical processes, including temperature, pressure, and motion.

  4. Biomedical applications: Silicon wafers are used to create a variety of biomedical devices, such as biosensors and lab-on-a-chip systems, which can be used for disease detection and drug discovery.

Overall, the unique properties of silicon wafers, including their electrical conductivity, thermal stability, and biocompatibility, make them an essential material in modern electronics and many other industries.

Ultrasonic Cleaning Steps

Ultrasonic cleaning is a process that uses high-frequency sound waves to remove contaminants from materials immersed in a solution. It is commonly used in industrial cleaning and also in many medical and dental procedures.

The ultrasonic agitation caused by the sound waves generates cavitation bubbles that implode and dislodge gunk, grime, grit and other surface contaminants.


Ultrasonic cleaning is a very powerful yet gentle process that can be used to remove dirt, grease, oil, dust, and other contaminants from many different substrates. These include metals, glass, and ceramics.

Using the correct agitation frequency (about 18 kHz), an ultrasonic cleaning solution is passed over the surface of a part to be cleaned. As the solution is agitated, the microscopic bubbles implode, forming jets that travel at high speeds toward the surface of the part to be cleaned. The jets can penetrate into crevices and reach deep into the material.

Aside from the cavitation energy, a variety of other substances can be added to an ultrasonic cleaning liquid to enhance its scrubbing power and improve the overall process. These substances include alkaline detergents, acids, enzymes, and other special chemicals.

Detergents, in particular, are an important ingredient in the ultrasonic cleaning process because they emulsify oils and reduce the surface tension of the water. This results in more effective cavitation and better rinsing of the cleaned parts.

These detergents can also be formulated to act as an acid to help remove oxides, corrosion, and other mineral deposits from the substrate being cleaned. For example, a solution with an acidic pH of five or less can be formulated to remove corrosion and limescale from ferrous metals.

However, care must be taken when choosing a cleaning solution to use with an ultrasonic cleaner. Some solutions can cause severe damage to the inner lining of an ultrasonic cleaning tank and may even damage the device itself.

The best detergents for ultrasonic cleaning are based on a chemical formula that is nontoxic and environmentally friendly, but still meets the requirements of the industry. These chemicals can be based on solvents like 1,1,1-trichloroethane or freon, but some are designed specifically for ultrasonic cleaning applications.

The main advantage of these types of detergents is that they can emulsify the oils in an ultrasonic cleaning solution to make rinsing easier. This can be especially helpful when there are hard-to-reach areas of the cleaning solution that must be rinsed.


Ultrasonic cleaning is the process of using high-frequency sound waves (outside of human hearing range) to clean a substrate. The sound waves produce cavitation bubbles which implode at very rapid speeds, operating as powerful microscopic vacuums. When the bubbles are ejected from the tank, they pull debris off the surface of the object being cleaned.

There are several different types of ultrasonic cleaner solutions, or chemistries, each designed for a specific cleaning task. These include acidic, alkaline, solvent replacement, and de-ionized water-based ultrasonic cleaner solutions.

A common acidic ultrasonic solution is formulated for removing lime deposits, scale, rust, and mineral from ferrous metals. It also works well for washing metal objects such as jewelry and watches.

Alkaline ultrasonic cleaner solutions have a pH of 10 or higher and are used for washing tin, brass, zinc, copper, stainless steel, cast iron, and steel. They also work well for cleaning plastics, ceramics, and glass.

Specialized cleaning chemistries are available for specific tasks, such as removing resins and waxes, soot and smoke damage, and maintaining first-responder equipment and firearms. These specialized formulations often contain surfactants which decrease water surface tension to increase cavitation, emulsify and disperse oils, and prevent corrosion.

They are also useful for cleaning a variety of materials, such as rubber, plastics, glass, fabrics, and metals. They are usually diluted to between 1 and 5% with water.

These solutions are ideally suited for industrial parts cleaning and can be paired with tank-less ultrasonic cleaners like Sonic Soak to achieve optimal results. They can remove light oils, greases and soils from a wide array of materials including aluminum, stainless steel, copper, brass, magnesium, and 3D printing parts as well as some plastics.

These solutions should be drained and rinsed after use to avoid the formation of water spots on the item being cleaned. They also need to be regularly wiped down and rinsed to ensure the tank does not get contaminated. This will keep the machine running efficiently and prevent the formation of a layer of dirt that dampens the ultrasonic wave and negatively affects cleaning performance.


The transducer is the main component of an ultrasonic cleaning system and is responsible for generating the high frequency ultrasound waves that are used to clean the substrate. A variety of transducers are available for ultrasonic cleaning applications. Kaijo uses a patented rectangular "Vibra-bar" module with two active piezoelectric stacks that are energized at two critical points to create a complex vibrational mode that produces multiple frequencies in the cleaning bath.

The "Vibra-bar" module is permanently bonded to a stainless steel radiating surface using a highly temperature cured adhesive. Each of the two active piezoelectric stacks is bolted to the radiating bar and one surface of each piezo element is electrically insulated from the backing plate by an insulator. This design eliminates adhesive between the piezoelectric elements and between the radiating bar and backing plate, resulting in increased reliability over other designs that utilize several piezoelectric elements.

When the patented "Vibra-bar" module is energized, piezoelectric crystals within the unit change their shape slightly. These changes cause the metal plate attached to the crystals to vibrate in tune with the ultrasonic frequency.

This causes compression waves in the liquid of the tank that 'tear' or 'cavitate' the fluid, creating microscopic 'voids'/'partial vacuum bubbles' which are used to remove contaminants from the substrate. This process is called ultrasonic cavitation and can be used to remove a wide variety of contaminants.

Most ultrasonic cleaners are built into a tank that contains the cleaning solution and the part to be cleaned. The tanks may be fabricated from stainless steel, or other materials that can withstand the erosion caused by ultrasonic cavitation.

Another common material for tanks is plastic, which can withstand the heat generated by the ultrasonic cavitation. However, the chemical properties of the cleaning solution must be compatible with the plastic to avoid corrosion and deterioration over time.

Some types of plastics can also adsorb energy, which can decrease the effectiveness of the cleaning process. This can result in a less thorough and more uneven ultrasonic cleaning.

The most effective ultrasonic generators are made from the highest quality parts and materials. This is crucial to achieving the desired cleanliness results while ensuring longevity and reduced downtime for maintenance. Additionally, the generator components must be durable enough to withstand the effects of harsh chemical exposure from the cleaning solution. Low-quality generators are more likely to fail, causing costly downtime and scrapping of expensive parts.


Ultrasonic cleaning is a process that uses sound waves to remove dirt and contaminants from parts. It is an effective method for removing grease, sludge, and other organic contaminants without harming the substrate. It is an efficient and effective cleaning system that is used in a wide range of industries.

It can also be used to clean delicate parts that are at risk of cavitation erosion and is ideal for cleaning semiconductor wafers, industrial components, and other sensitive electronics. This technology can be used to clean metals, glass, plastic, rubber, and other materials.

There are many types of ultrasonic cleaners, and they vary in size and function. Some are small toy-like systems, while others are large and can accommodate gallons of liquid.

Several factors affect the amount of power needed to clean a particular object, including the type of material it is made from, the cleanliness requirements of the item being cleaned, and the temperature of the tank in which it is being cleaned. Regardless of the specific application, it is important to choose an ultrasonic cleaning machine that provides the necessary power to efficiently clean your product.

The frequency of the sound waves that the ultrasonic generator creates is one of the most important factors in how effective an ultrasonic cleaner is. The higher the frequency, the more efficient the cleaning process will be.

Lower frequencies, such as 40 kHz, can cause a reduction in efficiency. However, this is not a serious problem for most applications.

Higher frequencies, such as 65 kHz or 170 kHz, can generate smaller cavitation bubbles and will remove finer particles more evenly. This means that it is better to use a higher frequency when the part being cleaned is delicate or has a large surface area.

Some ultrasonic cleaning machines use a combination of high and low frequencies. This allows them to reach deeper into crevices and spaces between the parts that they are cleaning, resulting in a more thorough cleaning.

It is also possible to switch between different frequencies when using an ultrasonic generator. Some generators can have 2 or 3 types of transducers, which enables true multi-frequency operation.