Stability of suspensions for applications in electronic
Common method
Suspensions of nanoparticles of platinium for example, typically used as catalyst in fuel cells, have a tendency to aggregate due to their small size and the high Van der Waals forced involved. Particle size measurements in such systems can be an issue, as dilution is often required and it changes significantly the charges of the system, leading to wrong results.
The Turbiscan LAB enables to monitor particle size and migration phenomena, without diluting the sample, hence analysing the sample in its real conditions. Different sample compositions can therefore be studied, looking at the interaction of the solvent, the nature of the particles or their size.
Using the Turbiscan LAB, the stability of fuel cells can be easily monitored, in real conditions of use (no dilution).
Application 2: Dispersibility of carbon nanotubes
Carbon nanotubes (CNT) are used in many different devices, due to the extra-properties they bring to the material they are incorporated in at only small amounts. However, their high aspect ratio (only tens of nanometer in diameter for couple of microns in length) leads to large aggregation phenomena. The properties is directly linked to their good dispersibility in the material and it is therefore important to test this property. Electronic microscopy (TEM, SEM) is commonly used to check the good dispersibility of the CNT. However, this is expensive and complex to perform on a routine base.
The Turbiscan LAB enables to identify and monitor the stability of CNT dispersions in a few hours. The measurement is done in the real solvent conditions, enabling to check the influence of the solvent on the dispersibility.
The Turbiscan LAB enables a quick and objective measurement of the dispersibility of CNT dispersions.Application 3: Stability of CMP slurries
Common method
CMP slurries are used to polish wafers at the Angstrom level. They are concentrated suspensions, where flocculation is a sensitive parameter, as it can lead to defect in the polishing. Particle size analysis is typically performed to check the size evolution, however, the important dilution required for the measurement (up to 1000 times) changes considerably the forces involved and can lead to a de-flocculation phenomenon, hence giving useless results.
The Turbiscan LAB allows a detection of flocculation phenomenon in concentrated dispersions, without dilution. Moreover, the vertical scanning enables to follow sedimentation and to compute migration velocity of the particles.
Using the Turbiscan LAB, stability of CMP slurries becomes easy and quick.
Many processes in the fabrication of electronic devices use suspensions at one point or another. Wafers are polished using CMP slurries, carbon nanotubes are incorporated in various materials to enhance their thermal, electrical or mechanical properties, fuel cells and flat panel displays comprise coated surfaces with nanoparticles, etc. All of these suspensions show typical colloidal instabilities (sedimentation, flocculation). Therefore, it is important to test their stability in the shortest possible time in order to improve the delay from development to production in a very competitive market. All these destabilizations can be monitored and quantified using the optical device TurbiscanÒ. Analyses are done on the real product, without dilution and can be automated and accelerated through temperature increase.
