Chemical Batch Sampling to 20 nm with the SLS-20
Sulfuric acid particle counters have special obstacles to overcome including background scatter, laser safety, bubbles, leaks, etc. All those topics are covered in detail in the paper, 20 nm Chemical Batch Sampling Solution.
The SLS-20 and Chem 20 sampling system is adept and efficient for batch sampling of a wide range chemicals, as evidenced by multiple customer use cases. This combination of Particle Measuring Systems technology is the most sensitive batch sampling system in the world, and its unique feature of mode switching enables the measurement of chemicals with normal and high molecular scattering properties. The additional features of shuttering the laser under precise conditions, detecting bubbles to ensure verifiable, repeatable data collection, switch activation in the event of low sample flow, and advanced leak signaling, highlight the key strides made to improve safety and efficiency of particle measurements for process chemicals in the microelectronics industry. The SLS-20 and Chem 20 system, together with SamplerSight software, is the ultimate solution for 20 nm chemical batch sampling.
The SLS-20 and Chem 20 system has been tested to sample contamination down to 20 nm in chemicals ranging from sulfuric acid to organic solvents. In this blog, we will be taking a look at the following solutions for process chemicals:
- Sulfuric acid particle counter
- PGME, PGMEA and PGEE particle counter
Switching Chemicals
PMS recommends never to allow the sample cell to dry out. When dry, the cell can leave contamination and residue that may create false counts that requires maintenance to correct. The best option for switching between chemicals is flushing enough water throughout the unit in between two chemicals. For safety, the inlet tube can be lifted to have the instrument flushed with ambient air to get rid of residual chemical, with an immediate flush of ultrapure water to thoroughly clean the residue. The new chemical can then be safely flushed into the unit for measurement.
Sulfuric Acid Particle Counter
The SLS-20 and Chem 20™ system is able to differentiate one lot from another based on 20 nm particulate levels in sulfuric acid. The SLS-20 and Chem 20-HI system was able to differentiate Lot 1 from Lot 2 for different processes during production. Overall, Lot 1 was 10% cleaner than Lot 2. For both lots, particle concentration at 20 nm was about one order higher than at 50 nm, indicating some room for quality improvement.
PGME, PGMEA and PGEE
This section covers test results for: propylene glycol methyl ether (PGME), propylene glycol methyl ether acetate (PGMEA), and propylene glycol ethyl ether (PGEE) solvent-based chemicals. Under High Scatter Mode, the SLS-20 and Chem 20-HI system identified the cleanliness of PGME, PGMEA and PGEE samples down to 24 nm. The filtered PGME sample was nearly twice as clean as the non-filtered sample. The filtered PGMEA sample was nearly 20% cleaner than the non-filtered sample, and the filtered PGEE sample was nearly 50% cleaner than the non-filtered sample.
Stay tuned for more process chemical study results in our next blog. Or… download the full paper here.
Learn more about Particle Measuring Systems 20 nm particle counting solutions for batch sampling solutions:
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