Silicon oxidation surface-controlled process

One assembly example is polyethylenamine (PEI)-mediated self-assembly of FePt nanoparticles [56]. PEI is an all -NH-based polymer that can replace oleate/oleylamine molecules around FePt nanoparticles and attach to hydrophilic glass or silicon oxide surface through ionic interactions [52], A PEI/FePt assembly is readily fabricated by dipping the substrate alternately into PEI solution and FePt nanoparticle dispersion. Figure 10 shows the assembly process and TEM images of the 4 nm Fes8Pt42 nanoparticle self-assemblies on silicon oxide surfaces. Characterizations of the layered structures with X-ray reflectivity and AFM indicate that PEI-mediated FePt assemblies have controlled thickness and the surfaces of the assemblies are smooth with root mean square roughness less than 2 nm. 

As shown in Table 10.5, non-metaUic fuels used as ingredients of pyrolants are boron, carbon, silicon, phosphorus, and sulfur. Similarly to metal particles, non-metal particles are oxidized at their surfaces. The processes of diffusion of oxidizer fragments to the surface of a particle and the removal of oxidized fragments therefrom are the rate-controlling steps for combustion. 

Figure 12.4 Fluorescence emission from biomolecules on ZnO NRs versus various control substrates after performing the identical biotreatment processes. (A) No fluorescence signal is detected on control substrates including glass, quartz, silicon oxide, silicon nanorods (SiNRs), and polymeric surfaces. On the other hand, strong fluorescence signal is observed from individual and striped ZnO NR platforms regardless of the spectroscopic properties fluorophores. (B) Normalized fluorescence intensity observed from biomolecules on various substrates. (C) Fluorescence...

The two principal etching solution systems for silicon are HF solutions and alkaline solutions. This is because silicon is inert in aqueous solutions due to the formation of an insoluble surface oxide except for H F solutions or alkaline solutions in which the oxide is soluble. Various chemical agents can be added into these two solutions to obtain a control on etch rate, etch selectivity, solution stability, and quality of the etched surface. One major difference between these two systems is that the etch rate of silicon HF solutions is similar among the various crystalline orientations, that is, isotropic, while in alkaline solutions it strongly depends on the crystalline orientation, that is, anisotropic. Another difference is that silicon oxide, which may be present on the silicon surface prior to or during an etching process, etches fast in HF solutions while it etches very slowly in alkaline solutions relative to the etch rate of silicon. 

In silicon based MEMS processing, common CVD films include polysilicon, silicon oxide, and silicon nitride. For polysilicon films (usually the structural layer), an LPCVD pyrolysis method is generally used with silane (SiH4) as the source gas [see Eq. (1)]. To obtain a imiform film across the wafer, the process is carried out at low pressure to ensure that the deposition is surface reaction controlled and not diffusion limited. Typical process temperatures are in the range of 580-650°C, and pressures between 0.1 and 0.4Torr. 

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