Ginam Kim

Nanoscale Composition of Biphasic Polymer Nanocolloids in Aqueous Suspension

The molecular distribution in nanocolloids of poly(dimethyl siloxane) (PDMS) and an organic copolymer (methyl acrylate co-methyl methacrylate co-vinyl acetate) preserved in a frozen aqueous solution was investigated using cryovalence electron energy-loss spectroscopy (EELS) coupled with a scanning transmission electron microscope. Low energy-loss spectra depend upon valence electron structure, and we show that they are substantially different for the PDMS, the copolymer, and the vitrified water studied here. Combining a high efficiency detection system and the use of high-signal low-loss spectra in EELS, we achieved a spatial resolution of 8 nm without serious beam-induced specimen damage in this radiation-sensitive soft-materials system. To obtain quantitative phase maps of silicone and copolymer composition within individual nanoparticles, spectrum datasets were processed via multiple least squares fitting. Quantitative line profiles from the resulting compositional maps indicate that the PDMS lobe of biphasic nanoparticles contained a significant amount of the copolymer and a diffuse interface was formed. Since the nanoparticle synthesis involves polymerization of acrylate monomer dissolved in PDMS nanoparticle precursors, these results suggest that the evolution of the nanocolloid morphology during synthesis is kinetically frozen as the acrylate copolymer achieves some critical molecular weight.

Development of Spin-on Pre Metal Dielectrics (PMD) for 0.10UM Design Rule and Beyond

Spin-on pre metal dielectric (PMD) materials are being developed for memory and logic devices at 0.10 um design rules and beyond. The stringent design rules require a PMD material with a low thermal budget, excellent gap fill capability, and etch resistance similar to that of a thermal oxide. Spin-on PMD is being developed to meet these requirements as current PMD technologies of HDP CVD and BPSG reflow are constrained by void formation or high thermal budget requirement. One common challenge that faces spin-on PMD is inhomogeneous densification, or “corner etch”. In this paper EELS-STEM, FTIR, SEM and HF wet etching were used to study the mechanism of this phenomenon. This information provides a possible route for the development of spin-on PMD resins.