How Clean are Your Seals ?

Trace, Test and The Importance of Cleaning Your Seals

During routine operation equipment will naturally wear. The components that are most at risk as those exposed to harsh chemicals or physical environments. Seals are no exception as they will slowly degrade over time. While this may not dictate the maintenance cycle of the tool itself, they will release by-products and impurities into the process environment making the material you choose to use vital, as lifetime alone is not enough to judge a seal’s suitability.

Trace metal contamination – How Clean are Your Seals

Contamination from seals falls under 2 categories:

• Alkali metals such as sodium (Na), potassium (K), and lithium (Li)
• Heavy metals such as copper (Cu), iron (Fe), zinc (Zn), titanium (Ti), and chromium (Cr)

The effects of the contaminants on a device will vary depending on the type of element. For example, Sodium can lose its outer electron and form an ion which can move through oxides even at room temperature. This can cause charge build-ups, voltage shifts and unstable outputs. While heavy metals can diffuse into the semiconductor reducing carrier lifetime and affect the device’s reliability leading to unstable performance, yield loss and increased costs.

Why Testing Matters

For many applications, testing for contamination by using the per million level is no longer enough. They now require parts to be tested at parts per billion using techniques like Vapour Phase Decomposition (VPD) and Inductively Coupled Plasma Mass Spectrometry (ICPMS), as these reflect the sensitivity of modern devices.

Even protective measures such as getting layers with PSG and BPSG are no longer a guarantee for contamination elimination, as moisture can release trapped mobile ions which reintroduces the risk to the process. Consumer demand is also increasing the pressure on for manufacturers to control contamination with their demands for faster, smaller and more powerful technology as the shrinking of devices makes the components even more sensitive to trace metal contamination due to their smaller dimensions and thinner gate structures.

Independent Testing and Results

Independent testing has shown clear differences between elastomer materials. Perfluoroelastomers (FFKMs) consistently achieved the lowest trace metal levels, with Perlast® G67P performing up to seven times better than the next best material. During testing, the fully organic, highly fluorinated elastomer (FKM) Nanofluor Y75N was also identified as one of the cleanest grades available.

The Importance of Material Selection – How Clean are Your Seals

These findings highlight the importance of material selection, especially in harsh environments where there are high temperatures, aggressive chemicals or plasma processes take place. By selecting high-purity elastomers it will help reduce contamination, protect wafers and maintain the device’s reliability.

E&OE. This information was gathered by our manufacturing partners. For more information contact a member of the team.