Improvements to the SPM Process Provides Significant Results

Wet bench semiconductor manufacturing relies on the SPM wafer cleaning process to quickly strip photoresist and other particles from silicon wafers. However, most semiconductor equipment manufacturers do not provide an efficient solution for using this process.

Modutek’s SPM Process involves the use of hydrogen peroxide for the stripping process. Because hydrogen peroxide in the sulfuric acid peroxide mixture is unstable, it continuously degrades into water and the degradation becomes faster if the mixture is increased with heat to increase the strip rate. That is why more hydrogen peroxide has to be added to keep the SPM concentration stable, spiking it back to its original level. After several repeated spikings, the mixture has to be replaced and disposed of.

Modutek has developed a “bleed and feed” method that keeps the SPM hydrogen peroxide concentration stable. It uses a two-tank configuration: one clean tank and a dirty tank.  An amount of mixture is drained from the dirty tank periodically and replaced with a mixture from the clean tank. The clean tank gets an amount of sulfuric acid to replace the drained amount, and both tanks now have enough hydrogen peroxide to bring the concentration up to its original level.

Modutek's “bleed and feed” method reduces the consumption of chemicals by 77%, while the volume of chemicals disposed at the end of the wafer cleaning process is minimized by 75%. Acid neutralizer and acid re-agent are reduced as well, plus the cost chemicals are also significantly reduced. As a result, savings from lower disposal volumes become more substantial.

To spike the mixture with hydrogen peroxide, frequent downtimes are required for drain and re-pour. However, with the use of Modutek's “bleed and feed” method, system drains are significantly reduced from three times per day to once per week on average. In addition to cost savings, the “bleed and feed” method leads to a reduction in chemical handling. As a result, it reduces the possibility of spills and increased operator and employee safety, while maintaining or improving previous levels of other SPM process characteristics at the same time. Customers – facility managers, process engineers, and researchers, etc. – can take advantage of the benefits provided by Modutek's “bleed and feed” method.

For more detailed information, read the complete article “Improvements to the SPM Process Provides Significant Results”. For a free consultation or quote contact Modutek at 866-803-1533 or email Modutek@modutek.com.

How the IPA Vapor Dryer Provides Superior Wafer Processing

After etching and rinsing, an IPA (isopropyl alcohol) vapor dryer can produce dry silicon wafers without watermarks and limited particle adders. IPA drying is also known as Marangoni drying, relies on the Marangoni effect of low surface tension of IPA compared to water.

When IPA vapor is introduced into the drying chamber in an IPA vapor dryer, a surface tension gradient is established between the IPA and water on the surfaces of the silicon wafers. The surface tension gradient causes water to flow off the silicon wafers and they are left clean and dry. In addition, the slow drain of water feature also helps to minimize particles that contaminate the wafer surfaces. It results to clean wafers after a final etch and before the next semiconductor manufacturing step.

IPA vapor dryers are particularly suitable for drying thin, delicate silicon wafers. It dries the wafers without moving them, unlike in other drying methods, and they are not subjected to any stress. As a result, any damage is minimized while the drying performance remains excellent.

The IPA vapor dryer improves wafer processing after the final hydrofluoric acid etching. The wafer has to be rinsed with de-ionized water and dried before undergoing the next manufacturing step. Providing a clean wafer with a low particle count is crucial at this stage because the following process steps will be affected by the presence of leftover contamination or particles. Because IPA vapor dryers remove water from the water surface and reduce particle counts with the Marangoni effect, the IPA vapor dryers improve wet processing equipment results and ensure higher quality output.

The complete article, “How the IPA Vapor Dryer Provides Superior Wafer Processing” goes into further detail. If you have questions, or you would like to set up a free consultation, contact Modutek at 866-803-1533 or email Modutek@modutek.com.