Silicon Wafer Cleaning: Effectively Removing Contaminants to Improve Yields

Silicon Wafer Cleaning: Effectively Removing Contaminants to Improve YieldsSuccessful semiconductor manufacturing relies on the effective cleaning of silicon wafers at several stages of the manufacturing process. Impurities, contaminants and residues from process steps have to be completely removed to ensure that the manufactured components have the required functionality and the desired quality. Silicon wafer cleaning equipment such as those offered by Modutek helps increase yields and improves the cleaning process to deliver high quality results.

RCA Cleaning

Standard RCA cleaning, named after the RCA Corporation where it was developed, involves immersion of the silicon wafers in hot acidic and alkaline solutions. The first bath usually contains hydrogen peroxide and ammonium hydroxide while the second bath has hydrogen peroxide with hydrochloric acid. The first solution removes organic contaminants from the surface of the silicon wafers by dissolving the bonds binding the contaminant particles to the silicon and by the oxidizing action of the chemicals. The second solution dissolves and removes alkaline residues and metallic particles.

RCA cleaning is the most common cleaning method used in the semiconductor manufacturing industry. It is especially effective in removing particles responsible for defects in semiconductors. When detected, such defects reduce the semiconductor yields of the manufacturing process and, if not detected, they reduce the quality of the resulting components.

Megasonic Cleaning

Cavitation bubbles created by the use of megasonic cleaning systems complement the chemical cleaning action of RCA cleaning. As semiconductor geometries become smaller and smaller in size, microscopic particles become more important in the creation of defects. Particles that might be too small to impact the function of large components become critical defect-producing factors for the smallest semiconductor structures.

The bubbles of megasonic cleaning systems add a mechanical component to the overall cleaning action. When the cavitation bubbles burst, they release energy that helps dislodge contaminant particles from the silicon substrate. This mechanical cleaning action can speed up the overall cleaning process and make it more effective in removing even the smallest particles.

SPM Clean – Piranha Etch

When silicon wafers are heavily contaminated, for example when contaminants are clearly visible or for the removal of photo resist after wafer processing, piranha etches provide a powerful cleaning method. The cleaning solution is made up of a mixture of hydrogen peroxide and sulphuric acid. The solution is highly corrosive and yields aggressive cleaning to remove large amounts of material. Sometimes wafers can be run through a piranha etch treatment before further cleaning with the RCA method.

FEOL and BEOL Processing

Front End of Line (FEOL) processing is the part of semiconductor manufacturing in which the components, such as transistors, are created in the semiconductor wafer, while Back End of Line (BEOL) processing involves depositing the metallic interconnections. Cleaning may be required after etching, after ion implantation or after metal deposition to remove process residue.

Water-based cleaning removes some of the impurities and RCA cleaning or piranha cleaning may be used to remove masks, photo resist or chemical residue. Ultrasonic cleaning is effective in helping remove particulate contaminants and ozonated deionized water may be used as well. At the end of each cleaning process, the wafers may be dried with isopropyl alcohol (IPA) in preparation for further processing steps.

Silicon Wafer Cleaning Equipment

Modutek has specialized in silicon wafer cleaning equipment for the semiconductor manufacturing industry and can deliver a complete spectrum of semiconductor cleaning solutions. In addition to chemical cleaning stations, Modutek incorporates the use of Megasonic cleaning equipment and IPA dryers.

Modutek silicon wafer cleaning solutions are based on the company’s thirty years of experience in providing semiconductor manufacturing equipment to the semiconductor industry. Modutek’s team of engineers can advise customers on the choice of equipment and design custom cleaning solutions for a wide variety of applications. If you need reliable and effective silicon wafer cleaning equipment in your manufacturing process, contact Modutek at 866-803-1533 or email

Certifications and Support for Wet Benches and Wet Processing Equipment

Certifications and Support for Wet Benches and Wet Processing EquipmentWet benches and associated semiconductor manufacturing and processing equipment use corrosive chemicals in electrically powered equipment that must be designed to high levels of safety. Certifications of compliance with applicable standards are a key factor in giving customers the confidence that their equipment is well designed and safe to use.

Customer support is another important factor in achieving exceptional customer satisfaction. Guaranteed warranty support and a high level of customer service ensures that customers can operate the equipment they have purchased for their application. Modutek provides wet benches and wet processing equipment with extensive certifications, comprehensive warranties and customer support for service, repairs and customization to help ensure that customers are completely satisfied with their purchases.

UL508a Standard for Industrial Control Panels

Modutek’s electrical panels are wired according to UL 508a. The standard specifies safety features such as protection against live electrical parts and the grounding of electrical equipment. It gives guidelines for the sizing of circuits, the sizing and routing of wiring and the placement of disconnect switches. Such standards become extremely important for both the safety of the operators and the protection of equipment because compliance with them reduces the risk of overheating or short-circuits in the electrical system. When wiring and circuits are correctly designed and sized, they function safely without dangerous temperatures. When technicians can easily disconnect circuits to test or repair components, the risk of injury to personnel and damage to equipment are reduced.


The National Fire Protection Association standard 70 is the National Electrical Code. The code governs the safe design, installation and inspection of electrical systems. Where UL508a deals specifically with Industrial Control Panels, the NEC treats the same topics and risks for whole electrical systems and installations. In addition, it specifically addresses systems in hazardous locations. Modutek’s systems are wired to fully comply with NFPA 70 and the NEC and they offer a high level of safety and operational reliability.


The National Fire Protection Association standard 79 deals with the safety of industrial machinery. The standard focuses on electrical safety and reliable operation of electrical and electronic equipment in industrial machines. In addition to design elements common to industrial panels and systems as described in the UL and NEC standards, NFPA 79 deals with the physical environment and operating conditions of the installation. The standard specifies what operational safety controls are required, such as emergency off buttons and interlocks, and it gives guidelines for testing and for documentation. Modutek’s wet benches fully comply with this standard and are designed to provide safe, reliable operation.

Other Certifications, Standards and Support

Modutek’s wet benches are wired in accordance with the above standards but the company carries out additional testing and further certifications are available. All benches are tested using deionized water and they are guaranteed for one or two years. Extensive customer support for upgrades, customized solutions and field service is also available.

If required, Modutek can supply third-party certification for the above standards and also for a SEMI S2/S8 Safety Assessment, Ashare 110 Fume Hood Testing, CE Mark (European Testing), CSA (Canadian Standards Association) and AS/NZS3000: 2007 (Australian/New Zealand Standard). These certifications can give customers additional confidence in the high level of safety and exceptional quality of Modutek’s wet benches and in the compliance of Modutek’s systems with applicable standards.