Improving Piranha Etch Process Results in Silicon Wafer Cleaning

Piranha etch, a popular process for silicon wafer cleaning, has to be tightly controlled in order to be effective. It consists of a mixture of about one-part hydrogen peroxide and three parts sulfuric acid, which quickly removes organic matter from silicon wafers. A heated quartz tank is used where both chemical concentration and temperature controls the etch rate.

Maintaining precise control of the original solution is difficult as it is exothermic. The temperature needs to be maintained between 130 and 180 degrees centigrade. The hydrogen peroxide decays to form water, diluting the solution, and the rate of decay depends on how high the temperature is. To prevent the solution from diluting, extra hydrogen peroxide is added to it. However, adding hydrogen peroxide also increases the temperature, which in turn speeds up the diluting process.

The mixture, with periodic spiking of the hydrogen peroxide, has a useful life of only one day. To address this Modutek introduced the "Bleed and Feed" process control strategy that improves the process while reducing chemical use. It also helps increase the useful lifespan of the mixture.

In the "Bleed and Feed" process, Modutek uses a two-tank "clean" and "dirty" tank design. When the hydrogen peroxide concentration in the "dirty" tank decreases, a small amount of mixture is drained from the tank and is replaced by the same amount from the "clean" tank. Then, the "clean" tank takes in a fresh amount of mixture.

The mixtures in the clean and dirty tanks are all programmable so that the desired concentrations can be maintained for an extended period. Using this method leads to the much longer lifespan of the Piranha mixture.

Below are the benefits of using Modutek's "Bleed and Feed" process control in Piranha etch process:

·         Better control of the process increases the reliability of strip results.

·         Replacing the mixture less often reduces downtime.

·         Chemical purchase and disposal costs become lower.

·         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.

·         The Risk of an accident from adding too much hydrogen peroxide is eliminated.

Learn more about how Modutek continues to improve their silicon wafer cleaning equipment by reading the entire article, “Improving Piranha Etch Process Results in Silicon Wafer Cleaning.” If you have questions, would like a free quote, or to set up a consultation, email Modutek at modutek@modutek.com or call 866-803-1533.

Modutek's History of Innovation, Customer Support and Satisfaction

Modutek Corporation has been a leading manufacturer of wet bench stations and semiconductor equipment for 40 years. The company continues to work with clients to improve process results and meet their needs.

Modutek emphasizes the three aspects of its operations:

1)   Constant innovation

2)   Customer support

3)   Customer satisfaction

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

Modutek manufactures high quality and reliable equipment by using quality materials for proven manufacturing processes. When manufacturing wet bench components, Modutek focuses on quality and produces equipment that provides high reliability. High quality and reliable equipment results in low downtimes and quality results.

The company prides itself on developing innovations that provides customers with solutions. By working closely with customers to understand about their needs Modutek provides solutions that incorporate state-of-the-art technology to improve process results.

Modutek is a wet bench manufacturer that designs their wet bench equipment in-house and does not use third parties. Manufacturing takes place in the company's plant in San Jose, and the software used in the process was also written and programmed in-house by Modutek's engineers. Customers get high quality reliable equipment as well as exceptional customer service and support.

 The company offers a complete line of wet process equipment that includes complete systems, individual stations, and process components. Stations are available in manual, semi-automated, and fully automated, and they can incorporate auxiliary functions such as an IPA vapor dryer or chemical handling station.

Apart from designing and developing standard components, Modutek can also modify its standard designs to meet specific customer needs. Because Modutek builds all of its products in house, it can change dimensions, use special materials, and integrate other functions into a system or program how specific processes run. Combined with their experience and expertise, Modutek can examine customer requirements to develop the corresponding equipment.

Read the complete article, “Modutek’s History of Innovation, Customer Support and Satisfaction,” to learn how Modutek became one of the leading semiconductor equipment manufacturers. If you would like to set up a consultation or get a free quote, contact Modutek at 866-803-1533 or email modutek@modutek.com.