Choosing an Acid Neutralization System to Safely Handle Chemical Disposal

Wet process semiconductor manufacturing lines use aggressive chemicals to clean and etch silicon wafers. Once the cleaning or etching step has been completed, disposing of the remaining chemicals safely is necessary.

Before being discarded, the remaining chemicals have to be neutralized first. For instance, low pH acids (like hydrochloric acid) have to be neutralized with high pH chemicals, so that it can reach the neutral value of seven. An acid neutralization system can be used continuously or in batches, and either process can be fully automated.

An acid neutralization system can be used with little supervision and will record chemical use and discharge to demonstrate compliance with environmental regulations.

The choice of acid neutralization reflects on the type of semiconductor manufacturing that takes place. For example, a continuous flow of waste chemicals is usually the result of large-scale continuous manufacturing. Therefore, a continuous acid neutralization system is ideal for this situation, as it can be designed to neutralize the outflow automatically and reliably.

The neutralization of waste chemicals in batch manufacturing is usually more complicated because each batch is different. Batch manufacturing usually takes place in developing prototypes, unique components, or small quantities of special parts. Therefore, batch neutralization is used, where the pH of the waste chemicals is measured and added with specific neutralizers (instead of adjusting chemical dosages of an established process like as in the continuous flow systems).

Once the choice of continuous flow or batch system is made, the acid neutralization system must fulfill a few basic requirements. The system capacity must be sufficient for the proposed application, with capacities ranging from a few gallons to a hundred gallons per minute. If automated, the exact automatic functions have to be programmed and set up. Finally, the monitoring and record-keeping functions have to be determined.

Another thing to be considered is the operational characteristics. If the system is automated, it may operate without supervision, but alarms will be required for situations such as low chemical supply or a pH level going beyond allowable limits. Recording of neutralization process parameters can be done digitally, with a log or on a chart recorder. Spill detection has to be incorporated into the alarm system as well, and the whole operation has to comply with environmental regulations.

For more details, read the complete article, “Choosing an Acid Neutralization System to Safely Handle Chemical Disposal”. The article discusses Modutek’s acid neutralization systems and how they can be customized to meet specific needs.  Contact Modutek at 866-803-1533 or email Modutek@Modutek.com if you have questions or would like to set up a free consultation.

5 Important Things to Know Before Buying a Wet Bench Station

Wet benches used in semiconductor manufacturing have many variations and include unique features based on the application requirements. There are several main things to consider before deciding what equipment is best suited for a specific manufacturing task. These include the type of station, how it operates, how it receives its chemicals, and what specialized or custom features are required. Five main things influence which type of wet bench to buy. 

1)     Different types of wet bench process stations have different advantages – White polypropylene construction is used for acid and base process applications such as KOH and RCA clean. Solvent application wet benches for processes using acetone, IPA, and photo resist stripping have a stainless-steel construction. Stations come with a dry-to-dry process and can include a chemical fume hood.

2)     The degree of automation depends on the application – Manual stations are ideal for initial development work when the main process parameters are yet to be determined. Once the overall process has been set, semi-automatic stations can program the fixed parameters to run automatically. At the same time, some variables can be controlled manually for optimization processes. Once the process is fully developed, fully automated stations can be used to run the production line and increase throughput.

3)     Chemical delivery systems improve process control – Chemical delivery systems run and monitor chemical storage, delivery to the process, and disposal of chemical discharges.

4)     Rinsing and drying are critical for avoiding particle contamination – Particles on wafers cause product defects. Rinsing and drying are crucial step processes as they help reduce particles on wafers, which leads to improved process yields. Special configurations such as the combined rinsing and drying station and the quick dump rinser improve process efficiency and reduce the particle count.

5)     Special custom functionality can be built into standard stations – Semiconductor equipment manufacturers that produce their own wet bench process stations in-house can add custom functionality depending on the application. For instance, the application may require etching of aluminum layers on a wafer, and a special vacuum metal etcher may have to be incorporated in the wet bench process.

Read the complete article “5 Important Things to Know Before Buying a Wet Bench Station” to learn more about Modutek’s wet benches. If you have questions, or would like to schedule a free consultation to discuss your process requirements, contact Modutek at 866-803-1533.