Achieving Optimum Particle Removal in a Wet Bench Process

As component packing becomes tighter and circuit geometries go toward smaller structures, the removal of submicron particles during a wet bench process becomes more important to achieve output quality.

As circuit paths reduce in size, even a single submicron particle can block the path, resulting in a defective final semiconductor component. The submicron contamination can negatively influence semiconductor performance, reducing the quality and lifespan of the products.

Therefore, innovative solutions, such as the use of Megasonic cleaning and the reduction of wafer handling with a single IPA dryer can help reduce the submicron particle count. When such solutions are integrated into the wet bench processing line, throughput yields can increase.

The use of high-frequency sound waves in cleaning systems is common in many industries. But Megasonic cleaners use remarkably high frequencies (950 kHz and higher, in the megahertz range) to deliver gentle but thorough cleaning of these delicate silicon wafer structures and surfaces.

The sound waves from low-frequency systems generate microscopic but comparatively large bubbles in the cleaning bath. These low-frequency bubbles deliver an intense scrubbing action. However, they are too powerful that they can cause pitting and damage on the surfaces of the delicate silicon structures.

In Megasonic cleaning, the high-frequency sound waves generate comparatively small cavitation bubbles and more gentle scrubbing. While these tiny bubbles are strong enough to dislodge contaminants, they are also gentle enough to preserve silicon surfaces and structures.

The most common way how silicon wafers become contaminated with submicron particles is during the transfer from etching to drying stations. Particles remaining on the surface can interfere with the subsequent fabrication process.

A single chamber handles HF last etching (which uses hydrofluoric acid) and IPA drying. After the HF etching is done, the silicon wafer is rinsed with de-ionized water until the acid is neutralized to a safe pH. The IPA vapor is then introduced into the station chamber and after about 15 minutes, the wafers are dry and ready for the next fabrication step. Because the wafers have not been moved throughout the etching drying process, the particle count remains low.

Modutek understands that not every customer will have the same needs and will work with customers to find solutions that work for their application. Providing customized solutions for customers has helped Modutek become a leading wet bench manufacturer.

Modutek has partnered with Kaijo Corporation to provide industry-leading Megasonic Cleaning systems that is incorporated into their wet bench stations. This technology provides a way to significantly reduce particle contamination and the use of chemicals in semiconductor manufacturing.

To learn more, read the complete article titled Achieving Optimum Particle Removal in a Wet Bench Process. Contact Modutek at 866-803-1533 or email Modutek@modutek.com if you have questions or would like to set up a free consultation.