Back to allHow to manage particles in a UPW system?
If you are involved in ultrapure water (UPW) technology as a UPW user, system operator, or supplier you should/must be interested in particle control. The International Roadmap for Devices and Systems (IRDS) and the industry in general recognizes that particles are potentially among the most critical factors for defects generated within UPW system, even more so for leading edge semiconductor technology. As microchip geometries move towards close-to-atomic scale, the critical or killer particle size (currently ~3.5 nm as defined by IRDS) has become smaller than the capability of advanced measurement techniques. This situation has been true in UPW for nearly a decade, with particle metrology suppliers investing in closing the gap, while the gap has only been increasing. The presence of dissolved particle precursors (defined as dissolved high molecular weight polymers) makes this even more of a challenge, because UPW systems were not designed to treat or prevent the release of particle precursors.
What makes particles so difficult to control?
- Metrology – No widely available metrology exists to monitor sub-10 nm particles.
- Filter Performance – Filtration capability at the killer particle size is marginal.
- Particle Precursors – Dissolved high molecular weight polymers may become killer particles when they attach to the wafer and the water dries out.
- High Purity Materials – High purity materials, such as filters and ion exchange resin, shed significant number of particles at killer sizes and larger.
- Controlling Colloidal Silica – Colloidal Silica needs to be controlled. It is commonly present in UPW and very difficult to detect with existing measurement technologies. It is most difficult to maintain with current filtration processes.
What can I do about it?
If you are involved in ultrapure water (UPW) technology as a UPW user, system operator, or supplier you should/must be interested in particle control. The International Roadmap for Devices and Systems (IRDS) and the industry in general recognizes that particles are potentially among the most critical factors for defects generated within UPW system, even more so for leading edge semiconductor technology. As microchip geometries move towards close-to-atomic scale, the critical or killer particle size (currently ~3.5 nm as defined by IRDS) has become smaller than the capability of advanced measurement techniques. This situation has been true in UPW for nearly a decade, with particle metrology suppliers investing in closing the gap, while the gap has only been increasing. The presence of dissolved particle precursors (defined as dissolved high molecular weight polymers) makes this even more of a challenge, because UPW systems were not designed to treat or prevent the release of particle precursors.