Particles in UPW: are there some possibilities to achieve lowest particle numbers in the 10nm size range?
Particles (mainly nano-particles) are the biggest challenge due to the fact that semiconductor structures are becoming smaller and smaller. Getting low particle numbers and sizes are essential to an optimal – in all details – UPW- process design. The choice of implementing the right material of constructions, hydraulic designs and process components (like high purity ion exchange resins in the polishing sections, etc.,) is crucial in making sure particles are not released from these materials as well. The last processing stages of an UPW plant are mostly microfiltration and ultrafiltration, which efficiently remove most of the micro and nano-particles present. Currently, we are limited to monitoring online particles in the range of >25-50nm. In the future, maybe nano-filtration will have a role to play here, with the big issue being the ability to measure and monitor these nano-particles online. Until then, online monitoring devices and membrane processes will need to improve and innovate in order to follow the semiconductor trends in regard of particles sizes. A big challenge.