When silicon wafer yields are not improved with the Standard Clean process, improved particle removal can be achieved with advanced processing equipment. Standard Clean or RCA clean was developed by the RCA company in 1965 and it has changed little since then. It has always been successful in cleaning wafers and removing most particles. However, with silicon circuits and structures decreasing in size and product density on wafers increasing, even the tiniest particles can cause device defects.
RCA clean works by first dissolving and removing organic materials from the surface of the wafers using powerful chemicals. In a second step, metallic impurities are removed and the wafer is rinsed clean. The two-step process and the rinsing remove most particles but the smallest particles often remain attached to the wafer with surface tension and electrostatic charges. Such particles can affect diffusion in wafers or block the etching of electronic structures or circuit paths.
The submicron particles are hard to remove completely with chemicals or by rinsing. The use of megasonic cleaning technology to generate very high-frequency sound waves in the wafer bath provides the capability to dislodge all remaining particles, allowing them to be rinsed away. Megasonic cleaning improves Standard Clean particle removal process and helps ensure defect-free production of microscopic structures on the silicon wafer.
How Megasonic Cleaning Works to Improve Standard Clean Particle Removal
The two steps making up the RCA wafer cleaning process are SC1, using a mixture of ammonium hydroxide and hydrogen peroxide, and SC2, using a mixture of hydrochloric acid and hydrogen peroxide. The SC1 process removes most of the contamination from the silicon wafer surface, but introduces metallic ion contaminants that can influence subsequent wafer processing steps. The SC2 process dissolves the remaining contaminants, allowing impurities to be rinsed away as they float to the surface of the cleaning mixture.
Standard Clean takes place in heated inert tanks such as quartz baths that are carefully designed to limit additional contamination. The chemical mixtures are heated to about 80 degrees centigrade and processing takes about 10 minutes for each step. After rinsing, the silicon wafers are clean but may still have an unacceptable number of submicron particles adhering to the wafer surfaces.
Megasonic cleaning can remove the majority of these particles while also dislodging the few larger particles that may still be present. The process involves adding a megasonic transducer to the tank holding the wafers. The transducer converts very high-frequency signals from a megasonic generator into sound waves that travel through the rinsing water to strike the wafer surfaces. Sound wave frequencies are typically at or above 1 MHz but may range as low as 200 kHz depending on the specific cleaning application.
As the sound waves travel through water, they create microscopic cavitation bubbles that form and burst in tune with the sound wave frequency. When the bubbles burst, they produce tiny but intense jets of water. The jets from the bubbles near the wafer surfaces dislodge any remaining particles, leaving them to be rinsed away at the surface of the bath, for example via an overflow weir. The additional Megasonic Cleaning step is very effective in particle removal because the tiny jets break any bonds that make the particles adhere to the wafer. The result is extremely low particle counts on wafers that undergo both the RCA wafer cleaning process and Megasonic Cleaning.
Modutek Designs and Builds Specialized Equipment to Improve Wet Bench Processes
Megasonic Cleaning is one example of Modutek’s implementation of designs and technologies that improve wet process performance for their customers. For over forty years Modutek has been providing specialized semiconductor manufacturing equipment to meet unique industry needs. As a leading semiconductor equipment manufacturer, the company offers free consulting and can provide recommendations on equipment from its complete product lines. When Modutek supplies wet bench equipment to customers, the company follows a well-defined process to ensure their equipment performance meets customer requirements.
Wet bench semiconductor manufacturing has many variations and applications often have unique features. Before buying a wet bench station, there are several main things to look at before deciding what equipment is best suited for a specific manufacturing task. Options include the type of station, how it operates, how it receives its chemicals and what specialized or custom features are required. When a prospective supplier has extensive experience and the required expertise as well as offering a complete line of wet bench equipment and customization as required, the selection becomes easier. Five main things influence which of the available 
With 40 years of success as a manufacturer of wet bench stations and semiconductor equipment, 
Modutek is continuing business operations during the COVID-19 pandemic because it is a supplier of critical components to essential businesses. The parts and systems Modutek supplies in wet process semiconductor manufacturing equipment are important for many businesses including those in the infrastructure and medical industries. At the same time, to support first responders and medical staff, the company is supplying components for face shields used in personal protection equipment. Modutek has re-prioritized its manufacturing capabilities to ensure that it can produce these critical components as needed.
Among the many processing steps involved in the manufacture of semiconductor components are high-temperature operations such as diffusion of materials into the silicon wafers. Quartz tubes are an ideal vessel for these process steps because the tubes can withstand the temperatures required and are inert enough to minimize contamination.
There are a number of things to keep in mind when you review which supplier to use from a list of 
The automation over the last 25 years of wet bench stations used for semiconductor manufacturing has resulted in more efficient production and an increase in output quality. When the handling and mixing of the chemicals, the handling of the silicon wafers and the timing of the process steps were carried out manually, mistakes could result in defective products. 
While the requirements for high precision control in wafer fabrication have increased, improvements in the fabrication equipment have also kept pace. The higher complexity and smaller size of semiconductor structures require extremely precise process control to ensure adequate output quality and a low component rejection rate. Advancements in automation and in reducing manual handling of the wafers have met these stricter requirements and allowed fabrication shops to increase productivity and reduce costs. Semiconductor equipment suppliers need to provide comprehensive automation solutions to meet in increasing requirements of manufacturers and research centers developing leading edge semiconductor devices.
Modutek is a supplier of wet bench technology, wet processing and chemical handling stations to the semiconductor fabrication industry. The company was recently named as one of the top suppliers in the 
Semiconductor manufacturing processes routinely use chemicals and procedures that could result in accidents if the manufacturer did not have a serious commitment to safety. Safety guidelines such as SEMI S2, published by the global industry association for microelectronics manufacturers, help manufacturers implement safe operating protocols. Ergonomic designs for