The stability of suspensions used in the electronic field is critical for guaranteeing the level of quality associated with high-technology end-products. For example, ultra-high definition displays rely on unique optical coatings and surface engineering of thin film structures to generate images of high quality. A chemical-mechanical polishing (CMP) uses slurries to polish the surfaces of semiconducting materials. The functionalities of fuel cells and batteries are improved with solution-processed nanoparticle coatings. There are myriad examples of the use of suspensions in established and cutting-edge electronic applications. Stability tests of suspensions can ensure that electronic devices in commercial and industrial spaces are fit for requirements.
Stability tests for suspensions used in electronic applications are concerned with instabilities such as sedimentation or flocculation. Tracking these phenomena enables analysts to predict the stability of suspensions over time, adjust the composition of suspensions for improved functional capacities, and achieve high-quality repeatable results for at-scale electronics manufacturing.
Here we will explore the importance of stability tests in electronics engineering with a focus on the use of chemical slurries in CMP processing.
CMP techniques use abrasive and corrosive chemical slurries to planarize the surfaces of substrate materials in preparation for lithographic electronic printing. Cerium(IV) oxide, or ceria, is routinely used as a chemical catalyst in the abrasive process. It accelerates the weakening of metallic surface particles on the semiconductor substrate and a mechanical polishing pad removes these particles from the surface. This process reduces topographic irregularities to provide a surface that is flat at the Angstrom level.
Ceria is a highly-efficient polishing media for semiconductor surface engineering, but it displays significant colloidal instability with a tendency for dispersed particles to sediment and agglomerate. This behavior can damage the efficiency of CMP surface engineering and cause mechanical defects in the semiconducting wafer. Surface variations of microscale proportions can significantly reduce the efficiency and functionalities of thin-film structures. This highlights the importance of performing robust stability tests of ceria suspensions used for CMP processing.
Stability tests for CMP suspensions are used to determine the efficiency of polymeric dispersants within ceria slurries, which are designed to inhibit the migration of dispersant particles in the liquid phase media. The Turbiscan LAB particle stability and size analyzer have been used for stability tests of ceria slurries based on the molecular weight of dispersants. Tests conducted at ambient temperatures of 35°C showed that ceria suspensions commonly display increased backscattered light at the bottom of the sample and increased transmission at the top of the sample. This is due to particle sedimentation over time.
These stability tests have enabled analysts to determine the short-term stability of formulations of various molecular weights, with results indicating that dispersants of higher molecular weights (longer polymer chains) allow for longer colloidal stability.
Formulaction is an expert in the analysis of colloidal stability, with a robust understanding of the complex variations in suspension stability tests for distinct applications. Our Turbiscan analyzers have been broadly applied to test the stability of suspensions for platinum nanoparticles in fuel cell applications, multi-walled carbon nanotubes, inks for plasma display panels, and many more applications.
If you would like any more information about performing stability tests with Formulaction, please do not hesitate to contact us or visit our library section to download related documents and application notes.