Papers by Keyword: Silicon Surface

Abstract: We investigated the change of optical second harmonic generation (SHG) intensity during In/Si (111) interface formation. It was proved that Si (111)2×2-In reconstruction is formed by one monolayer of In on silicon surface.

Abstract: Monocrystalline silicon texturization will be elaborate in this paper as a new method for texturing silicon surface. Normally, silicon surface will textured by using wet chemical etched. Some of crystalline wafer is ineffective when using conventional methods, because the different crystallographic orientation of regions of diversified consequence. Conventional method which is wet chemical etched always shown not uniform texture. So, the texturization with laser will introduce as a promising method in reducing reflection on silicon surface. This is the reason for conducting this research. Field Emission Scanning Electron Microscopy (FESEM) and digital microscope are performed to evaluate the results. Texturization of monocrystalline silicon surface by using Pulsed Laser Nd:YAG was found to be promising method in terms to avoid chemical texturing etched method. Compared to the conventional texturing method, laser texturization is much more independent on grains crystallographic orientation. Higher homogeneity texture can be reached when using laser Nd:YAG compared with chemical or electrochemical methods. The heat affected area caused by material damages is related with presented method limitation implementation practically. However, one step of chemical etching will be used to remove the damages after laser texturization. The main reason conducted this new methods are to reduce reflectance from bare or polished silicon surface and adapt it into solar cell manufacturing process. This new methods are expected to gives high efficiency solar cells.

Abstract: Well-defined amphiphilic graft polymer brushes containing fluoropolymer segments have been successfully prepared by (i) UV-induced coupling of 4-vinylbenzyl chloride (VBC) with the hydrogen-termined Si(100) (Si-VBC surface), (ii) surface-initiated atom transfer radical polymerization (ATRP) of 2-hydroxyethl methacrylate (HEMA) to produce the Si–VBC–g–P(HEMA) surface as the backbone of macroinitiator for further ATRPs, (iii) coupling of 2-bromoisobutyrl bromide with the HEMA polymer(P(HEMA)) by the esterification to produce the macroinitiators for the subsequent ATRP(Si–VBC–g–P(HEMA)-R3Br), (iv) surface-initiated ATRP of 2,2,3,3,4,4,4-heptafluorobutyl acrylate (HFBA) to produce the Si–VBC–g–P(HEMA)–g–P(HFBA) surface, and (v) the active P(HFBA) chain ends being used as the initiator for the subsequent ATRP of poly(ethylene glycol) monomethacrylate (PEGMA) to produce the amphiphilic Si–VBC–g–P(HEMA)–g–P(HFBA)–b–P(PEGMA) brush surface. The chemical composition and functionality of the silicon surface were characterised by X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) and ellipsometry.

Abstract: The adsorption and diffusion of polydimethylsiloxane (PDMS) with different chain lengths on a silicon (111) surface were studied by molecular dynamics simulations. The relative dielectric constant was selected to be 1 to mimic a vacuum. The chains were all present as two dimensional (2D) adsorption conformation on the surface but different conformations and dynamic properties were found in the two absolutely different environments. The relationship between the adsorption energy of the different chain lengths and the degree of polymerization follows a linear function and the average adsorption energy per segment is -0.42 kcal/mol. In addition, the diffusion coefficient (D) of these chains scales with the degree of polymerization (N) as N_-3/2.

Abstract: More and more, 300mm manufacturing promotes a single wafer tool approach in FEOL cleaning. Previously, we reported an advanced surface preparation process based on dilute HF/HCl/DIW and O3/HCl/DIW chemistries coupled with megasonic activation during the ozone step only, on a 300mm single-wafer platform [1]. As throughput consideration implies shorter process time, the activation of megasons during the whole cleaning step could be of interest for very small particle removal efficiency. Nevertheless, extending megasonic activation to the entire process sequence leads to degraded results on silicon surface. Indeed, damages are created at 90 and 65nm defect inspection levels when megasonic activation is used in the presence of both HF species and on hydrophobic silicon surface. In this paper, we demonstrate that the megasonic activation (Megs) generates randomly and locally oxidized species which may be the main cause of damages in the presence of HF chemistry. Additional characterizations are performed to understand this problem (haze inspections, ATR analysis and contact angle measurements).

Abstract: A unified theoretical and/or computational odd-electrons approach is suggested for molecules, surfaces and magnetic solids making possible their consideration on the same conceptual basis as well as on the same computational footing. The current paper presents the approach application to the chemistry of fullerenes, carboneous nanotubes, surface science of silicon crystal, as well as to the molecular magnetism of both solid polymerized fullerenes and molecular crystals composed of transitional metal complexes.