Monthly Archives: June 2020

Improving Piranha Etch Process Results in Silicon Wafer Cleaning

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Improving Piranha Etch Process Results in Silicon Wafer CleaningPiranha etch is a popular process for silicon wafer cleaning, but it has to be tightly controlled to be effective. The mixture of about one part hydrogen peroxide and three parts sulfuric acid rapidly removes organic matter from silicon wafers. The etch process takes place in heated quartz tanks where both temperature and chemical concentration affect the etch rate.

Precise control is difficult because mixing the original solution is exothermic, and the hot mixture is then maintained at between 130 and 180 degrees centigrade. The hydrogen peroxide decays to form water, diluting the mixture. The rate of decay depends on the temperature, but adding extra hydrogen peroxide to keep the concentration steady increases the temperature.

With several key variables interdependent, accurate control with traditional control systems is not easy and results can be varied. The mixture, with periodic addition or spiking with hydrogen peroxide, has a useful life of only about one day. Modutek has developed a control strategy that improves process results while reducing chemical use.

The Modutek “Bleed and Feed” Process Control Strategy Delivers Improved Results

Modutek’s “Bleed and Feed” process control strategy keeps the concentration of the Piranha mixture at the desired level while increasing the lifespan of the mixture. The company uses a two-tank “clean” and “dirty” tank design. When the concentration of hydrogen peroxide in the dirty tank goes down, a small amount of mixture is drained from the tank and is replaced by an equal amount from the clean tank. The clean tank then receives a fresh amount of mixture. The clean tank and dirty tank mixtures and the amounts of the bleed and the feed are all programmable so that the desired concentrations can be maintained for an extended period. Using the “Bleed and Feed” method, the Piranha mixture has a much longer life span.

“Bleed and Feed” Control Strategy Advantages

The control strategy of frequently adding small amounts of a programmable hydrogen peroxide/sulfuric acid mixture to the main “dirty” tank mixture to maintain its concentration provides several advantages to the silicon wafer cleaning process. Instead of spiking the mixture with hydrogen peroxide, the Modutek method adds an already mixed dosage to the main mixture, reducing temperature instability and allowing better control of the process. When the main mixture is relatively stable, it lasts longer and doesn’t have to be replaced as often. The temperatures and concentrations are more stable and the control of the etch or strip rate is more precise.

The Modutek “Bleed and Feed” Process Control Delivers Substantial Benefits

With more precise control of the process and a more stable Piranha mixture, Modutek’s “Bleed and Feed” process control improves Piranha etching results. Specific benefits include the following:

• Better control of the process increases reliability of strip results

• Precise temperature and concentration levels result in a constant strip rate

• Programmable dosage levels add control flexibility for predictable results

• Reproducing process parameters creates excellent repeatability

• Longer mixture life reduces chemical use

• Replacing the mixture less often reduces down time

• Chemical purchase and disposal costs are lower

• Risk of an accident from adding too much hydrogen peroxide is eliminated

Overall process results and wet etching performance are improved with the better outcomes and reduced costs of a Piranha etch process using Modutek’s “Bleed and Feed” process control. Customers incorporating Modutek’s new control strategy can expect reduced product failure rates, better output quality and overall improved wet process station performance.

Modutek continues to improve their silicon wafer cleaning equipment to provide customers with better process results using the “Bleed and Feed” process control in new wet bench stations. The company offers free consulting and can help customers choose an appropriate wet bench configuration or custom-build one to meet specific customer needs.

Modutek’s History of Innovation, Customer Support and Satisfaction

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Modutek's History of Innovation, Customer Support and SatisfactionWith 40 years of success as a manufacturer of wet bench stations and semiconductor equipment, Modutek Corporation continues working with customers to improve process results and meet customer needs. The company emphasizes the following three aspects of its operations.

1. Constant innovation, looking for aspects of wet bench technology that could be improved and finding solutions that produce excellent results.

2. Customer support. Because Modutek manufactures all its own equipment, it has the expertise to provide unparalleled support for everything the company delivers.

3. Customer satisfaction. Modutek uses raw materials and parts of the highest quality to deliver equipment that meets or surpasses customer expectations.

By building its operations around innovation and customer needs, Modutek has become a leading semiconductor equipment manufacturer.

Manufactures Reliable Equipment of the Highest Quality

The key to producing reliable equipment is to use high-quality inputs for proven manufacturing processes. When manufacturing wet bench components with materials such as quartz, Teflon and stainless steel Modutek specifies the highest quality and produces equipment with an excellent track record. The high equipment reliability results in low down times and high-quality output for customers.

Innovation that Provides Customers with Solutions

Modutek’s customer-centered approach directs innovation towards addressing customer problems. The company works closely with customers to learn about their needs and then develops solutions that incorporate the latest technology to improve process results.

Wet Bench Equipment that is Designed, Built and Programmed In House

Customers ordering wet bench equipment from Modutek receive one-stop solutions with no third parties. During concept, configuration and design customers work with Modutek specialists to translate their needs into wet process systems that can carry out the functions they want. Manufacturing is done at the company’s plant in San Jose and the software used in process automation is written and programmed by Modutek’s own engineers. With no third parties to call in and a seamless knowledge of the delivered systems, Modutek can provide exceptional service and support.

Delivering a Comprehensive Suite of Wet Process Equipment

Modutek is a wet bench manufacturer with a complete line of wet process equipment including complete systems, individual stations and process components. Stations can be manual, semi-automated and fully automated and they can incorporate auxiliary functions such as an IPA vapor dryer or chemical handling station.

Components making up wet process systems include Quartz tanks/baths, Teflon tanks, Solvent baths, Megasonic cleaning, Air Scrubbers, waste water treatment systems and Quick Dump Rinsers. Modutek can offer such components to be added to an existing facility or can assemble standard components to meet specific customer needs. In each case, Modutek can help establish what is required for a wet process application and recommend equipment from its own comprehensive line, ensuring that the equipment performs as expected.

Modutek Can Design a Custom Solution for all Wet Process Applications

Semiconductor manufacturing has many steps and an application often has unique requirements. Prototypes, models, research projects or proof of concept products can each require custom solutions. While Modutek has standard components in its product line, the company can modify its standard designs to meet specific customer needs.

Because Modutek builds all its products in house, it has the capability to change dimensions, use special materials, and integrate additional functions into a system or program how specific processes run. Tanks and baths can be built to fit existing spaces or match existing facilities. Wet bench stations can be programmed with exactly the right amount of automation, adding operator interventions at critical points. With its in house expertise, Modutek can examine customer requirements and build the corresponding equipment.

Combining 40 years of experience with its comprehensive wet process equipment product line and its extensive customization capabilities lets Modutek satisfy customers with effective results. Modutek also backs up its equipment with superior customer service and support. That record together with its innovative products makes Modutek one of the leading semiconductor equipment manufacturers.