How Silicon Wet Etching Processes Are Improved with Specialized Equipment

how-silicon-wet-etching-processes-are-improved-with-specialized-equipmentWhile Modutek’s wet bench equipment supports all common wet etching processes, the continuous development of new wet bench technologies allows the company to offer specialized equipment that can improve performance for specific applications. Key factors for high output quality, fast processing, high yields and reliable outcomes are cleanliness, repeatability, tight control and precise dosages. Modutek’s standard line of silicon wet etching equipment already scores highly on these factors but the company’s specialized equipment can further improve performance for certain processes.

Buffered Oxide Etch (BOE)

The BOE process requires tight and precise temperature control while filtering lowers the particulate count and reduced acid consumption results in lower costs. Modutek’s F-series sub-ambient circulation bath is specially designed for BOE applications and addresses these factors. The temperature controller is accurate to less than plus/minus one degree centigrade in a range from 10 to 60 degrees centigrade with sub-ambient capability. The circulating bath includes 10.0 to 0.2 micron filtration and is designed for low acid consumption. Using a wet bench system specialized for the BOE process can reduce costs and defects in products while providing safe and reliable operation.

Piranha Etching

The sulfuric acid/hydrogen peroxide mixture of the Piranha solution is extremely corrosive, and the mixture is exothermic when first prepared. The Modutek QFa Series of Quartz High Temperature Recirculating Baths are ideal for withstanding the high temperatures, first of the initial heating after mixing and then during the process that is heated to preserve mixture reactivity. The baths have heaters that can raise the temperature of the mixture by two degrees Centigrade per minute and the temperature controller can maintain the temperature at plus/minus one degree centigrade over a range of 30 to 180 degrees centigrade. These Modutek quartz baths are characterized by the high degree of safety, reliable operation and low cost of ownership.

Potassium Hydroxide (KOH) Etching

Modutek Teflon tanks are ideal for use in KOH etching because they can be custom fitted to any wet bench configuration and come in three models to satisfy common heating and recirculating requirements. The TFa and TI series of Teflon tanks are temperature controlled to an accuracy of plus/minus 0.5 degrees centigrade over a range of 30 to 100 degrees centigrade. The TFa series are overflow re-circulating models while the TI series are static. The TT series are static ambient temperature models. All Teflon tanks are made from PFA Teflon with special welding techniques to minimize the presence of undesirable by-products in the process and to reduce contamination. Modutek’s Teflon tanks improve KOH process control, increasing reliability and reproducibility of process conditions.

Silicon Nitride Etching

Etching silicon nitride with a phosphoric acid deionized water mixture is challenging because the concentration changes as the deionized water evaporates and because adding water to the process can cause an explosion. Modutek’s silicon nitride wet etching bath is specially designed to address these issues and provide reliable and safe process control. The mixture is kept at the boiling point, which changes as the concentration increases. Depending on the temperature of the mixture, small amounts of deionized water are added to the boiling mixture to maintain the concentration at the required level. Using the boiling point temperature as an indication of the concentration and allowing the boiling mixture to immediately distribute small amounts of water lets Modutek control the process while maintaining safe operation.

With its extensive experience in silicon wet etching process technology, Modutek can deliver specialized equipment suited to a particular process and help customers select the right equipment for their applications. With equipment specially designed for the process used, customers obtain superior results while often saving money as well. Contact Modutek for a free consultation or quote on using the right silicon wet etching equipment for your application.