Silicon Nitride Nanoparticles Research Articles

An effective way to stabilize silicon nitride nanoparticles dispersed in rubber matrix by a one-step process

In this work, a new graft copolymerization macromolecular coupling agent (LMPB- g-MAH) of maleic anhydride (MAH) onto low-molecular-weight polybutadiene liquid rubber (LMPB) was synthesized, and it was used to modify silicon nitride nanoparticles (Si 3N 4). The structure and surface properties of modified nano-Si 3N 4 were systematically characterized by FTIR, TEM, XPS, size distributions analyzer, TGA, dispersion stabilization in dimethylbenzene and contact angle measurement. It can be found that the optimum graft degree (GD%) and loading of LMPB- g-MAH is 9–11% and 10–12%, respectively. According to the spectra of FTIR and XPS, it can be inferred that LMPB- g-MAH covalently bonds on the surface of nano-Si 3N 4 particles and an organic coating layer was formed. The contact angle and surface free energy experiments show that the hydrophobic property of modified nano-Si 3N 4 is improved. TEM reveals that modified nano-Si 3N 4 possesses good dispersibility and the average diameter in dimethylbenzene is less than 60 nm. TGA indicates that the using efficiency of the macromolecular coupling agent is 44.66%. The oil resistance of SBR-based nanocomposites was also studied, which was improved greatly due to the modified nano-Si 3N 4.

Aging Phenomena in the Removal of Nano-Particles from Si Wafers

With the continuous shrinkage of critical sizes in semiconductor manufacturing, nano-particles smaller than 100-nm are becoming a potential threat to devices in chips. Storage of wafers contaminated during process steps often results in a decrease of particle removal efficiency in subsequent clean, a phenomenon referred to as aging. In this work, the influence of aging on the removal of silica and silicon nitride nano-particles from hydrophilic Si wafers was studied for different storage conditions. Trends observed for aging as a function of particle size and for different tools indicated that aging will become an issue for critical cleans where substrate etching must be kept very low and the physical component of the clean must be decreased to prevent damage to fine structures. Controlling the relative humidity during storage helped in lowering the effect of aging.

Thermodynamic analysis and experimental verification for synthesizing silicon nitride nanoparticles using RF plasma CVD

Silicon nitride nanoparticles were synthesized by radio-frequency (RF) plasma chemical vapor deposition (PCVD) using silicon tetrachloride and ammonia as precursors, and argon as carrier gas. By assuming chemical thermodynamic equilibrium in the system, a computer program based on chemical thermodynamics was used to calculate the compositions of the system at different initial concentrations and final temperatures. At first, five elements and thirty-four species were considered. The effects of temperatures, and concentrations of ammonia, hydrogen and nitrogen on the equilibrium compositions were analyzed. It was found that the optimal reaction temperature range should be 1200 to 1500 K to obtain the highest conversion and yield of Si 3N 4. The inlet position of ammonia should be lower than that of silicon tetrachloride, and both should be located at the tail of the plasma torch. The best mole ratio of ammonia to silicon tetrachloride was found to be about 6. Later, the influences of water (and oxygen) were considered, and 17 additional species were included in the computations. It was found that oxygen or water content in the raw materials should be as low as possible in order to have high nitride content in the produced Si 3N 4. Nitrogen or hydrogen might be used to replace some or even all the argon to improve the yield of silicon nitride and reduce the cost. The ratio of ammonia to silicon tetrachloride should be high enough to obtain high conversion, but not excessively high to reduce the oxygen content due to the existence of water in ammonia. The simulated results were verified by experiments.

Surface tension studies of (Si, N)-containing diamond-like carbon films deposited by hexamethyldisilazane

The (Si, N)-containing diamond-like carbon (DLC) films were deposited using hexamethyldisilazane (HMDSN) reactant in an inductively coupled plasma (ICP) system with the substrate biased by a bipolar-pulsed power supply. Raman spectra of the films were characteristic of a typical DLC film. X-Ray photoelectron spectroscopy (XPS) showed that silicon and nitrogen tended to be bonded to each other. From high-resolution transmission electron microscopy analysis, the diamond-like carbon contains silicon nitride nanoparticles. By measuring the contact angles with the sessile-drop method, the polar and the dispersive components of the surface tension were characterized. The surface tension of the pure DLC (a-C:H) was 26.6 mN/m. By incorporating nitrogen in the DLC film, the surface energy was increased to 33.6 mN/m. The incorporation of nitrogen enhanced the polar share from 8.6 mN/m to 25.6 mN/m, but reduced the dispersive share from 18.1 mN/m to 8.0 mN/m. The polarity of the film was greatly enhanced by the formation of carbonnitrogen bonds. By further incorporating silicon in the nitrogen doped DLC, the surface tension was reduced back to 24–27 mN/m, close to that of pure DLC films. However, the (Si, N)-containing DLC films had much higher polar shares and lower dispersive shares than those of pure DLC films. Both the effects of the substrate bias and the effects of normal aging on the surface energy of the (Si, N)-containing DLC films were also reported.

Preparation and evaluation of nitrogen-terminated silicon nanoparticles: laser annealing effect

Nitrogen-terminated silicon nanoparticles were synthesized on AFI AlPO4-5 zeolite by pulsed laser ablation of silicon target in the presence of 1.33×10−5Pa of ammonia and were annealed by multiple laser shots at 532nm. The samples were characterized by X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy and UV–vis absorption measurements. The results indicate that they are composed of nonstoichiometric silicon nitride nanoparticles as well as silicon species with dangling bonds. NHx (x=1,2) polyhydride species are dissociated by pulsed laser annealing, which shows the improvement of the silicon and silicon nitride crystallinities. It is suggested that the nanoparticles will agglomerate as clusters after laser annealing. According to the Tauc plot obtained from UV–vis absorption data, a blue shift of band gap energy from bulk silicon was observed.

Characterization of nitrogen terminated silicon nanoparticles on AFI zeolite with X-ray and ultraviolet photoelectron spectroscopies

Nitrogen terminated silicon nanoparticles were synthesized on AFI AlPO 4-5 zeolite by pulsed laser ablation of silicon target in the presence of 1.33×10 −5 Pa of ammonia, and were characterized in situ by X-ray photoemission spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). Nonstoichiometric silicon nitride and unterminated silicon nanoparticles with size of estimated to be ∼5.4 Å in diameter were existed. They were found to migrate and diffuse into the AlPO 4-5 channels at 373 K and migrate back to the external surface at 503 K. The effect of sample annealing was studied at 373 K. The change of silicon surface state (unterminated silicon nanoparticles) to hydride species was observed concurrently with breaking of the NH x species. This result implies that the NH x species remained on the silicon particles form Si 3N 4 like bonds and the dissociated H-species are bound to the unterminated silicon surface.