English
汉语
English
Français
Deutsch
TSI Nano LPM™ System — Frequently Asked Questions
Question
Why is detecting silica so important as compared to other optical-based technologies?
Answer
Silica is a dissolved inorganic material that causes significant damage to wafers. Semiconductor manufacturers spend millions of (Dollars, Euros, Won...) to filter UPW and remove silica, because if silica is in the UPW it easily causes wafer defects. The Nano LPM™ System is the ONLY liquid particle monitor that can detect silica in UPW, so customers can take action before it affects product quality.
Question
How does the TSI Nano LPM™ System fill a technology gap that current optical Liquid Particle Counters (LPCs) cannot meet?
Answer
Counting Efficiency is the gap between these technologies! The Nano LPM™ System provides 50% counting efficiency to detect ≥10 nm nanoparticles in ultrapure water (UPW). Current optical Liquid Particle Counters (LPCs) only provide ~3% counting efficiency at 20 nm. The Nano LPM™ System provides critical information to enable customers to make data driven decisions on the quality of their UPW.
Question
Why is there only 1 channel?
Answer
The Nano LPM™ System monitors nanoparticles continuously and reports particle concentration, not size distribution information. Monitoring changes and differences in particle concentrations are preferred when detecting nanoparticles that cause wafer defects.
Question
What about instrument-to-instrument repeatability and reproducibility?
Answer
Over two years of testing in semiconductor UPW sites has demonstrated that two instruments, side-by-side, sampling the same UPW source far exceeds repeatability and reproducibility data as compared to optical-based liquid particle counters.
Question
Has TSI performed any stability testing between an optical Liquid Particle Counter (LPC) vs a Nano LPM™ System?
Answer
Data comparison of optical Liquid Particle Counters (LPCs) vs. TSI Nano LPM™ System technologies does not provide quantifiable results. LPC data is affected by several factors including low first-channel counting efficiencies (~3% at 20 nm), optical contamination, bubble counts (i.e. false counts), and index of refraction challenges.
LPC’s ability to distinguish between materials of very similar index of refraction is challenged too. For example, the index of refraction for silica (1.46) and UPW (1.33) are close, meaning silica appears invisible to the LPC.
In contrast, the TSI Nano LPM™ System has 100% counting efficiency at 20 nm and, since the particles are removed from the UPW, there are no optical surfaces to contaminate, no bubbles, and the Nano LPM CPC is not influenced by the index of refraction difference, so silica and other particles are easily detected.
Question
Can the TSI Nano LPM™ System detect small differences in UPW resistivity (e.g. 18.2 MΩ-cm versus 18.1, 18.0 or more broadly, 18, 17, 16…)?
Answer
The Nano LPM™ System does not report UPW resistivity, but our system has shown to be far more sensitive and responsive than resistivity meters.
At TSI’s testing labs, our UPW system is not as refined as semiconductor UPW. Regardless, when a breakthrough of the main mixed bed filtration occurs, the TSI Nano LPM™ System counts drift upward, so it detects change long before (sometimes days) before commercially available resistivity meters report a change.
Question
What checks can we perform to ensure the Nano LPM™ System is correctly operating?
Answer
You can directly inject a particle challenge into the Nano LPM™ System’s injection port. Within minutes, you will see a response that assures you the Nano LPM™ System is working as designed. Also, the Nano LPM Software (included) monitors the Nano LPM™ System’s health —pressures, temperatures, flows and pump status are some of the key parameters monitored.
Question
Is there any customer-required maintenance?
Answer
TSI suggests replacing the Wicks in the Nano LPM CPC every 6 months. Other than that, the Nano LPM™ System will follow an annual calibration schedule.
Question
LPCs can detect gold 20 nm particles, but what about other particle types below that?
Answer
TSI calibrates the Nano LPM™ System with 20 nm silica nanoparticles. Then, we apply a detection efficiency calibration factor to the system, so it counts 100% of particles at 20 nm.
At 10 nm, the same calibration factor as above applies—but, the actual detection efficiency for silica particles at 10 nm may vary slightly from system to system. The Nano LPM CPC’s d50 (first-channel counting efficiency) is calibrated using 10 nm sucrose nanoparticles.
Question
Can customers send UPW samples with/without known contamination to TSI headquarters for analysis?
Answer
Handling and storing samples will contaminate them, so the system may detect the contaminants of the storage vessels and not the actual contaminants of your UPW. It is best to directly measure samples from the source.
You can take a small sample from a different UPW source and directly inject that sample into the Nano LPM™ System’s injector system. The reported data may still be skewed by the vessel’s contamination and transport to the Nano LPM™ System, so this test should not be considered a highly accurate representation of UPW cleanliness.
Question
How much volume is needed for batch samples and, per injection, for three (3) tests to demonstrate repeatability? How long does it take to do the samples?
Answer
Typically, a sample of ~100 mL of UPW is enough, the injected sampled delivered to the Nano LPM™ System will be ~1 mL. The sample must be prepared, perform the injection, and wait for the response. The total time to batch sample could be accomplished in under 20 minutes.