Poly silicon wafer surfaces with

Based on this approach Schouten et al. [254] attached a silane-functionalized styrene derivative (4-trichlorosilylstyrene) on colloidal silica as well as on flat glass substrates and silicon wafers and added a five-fold excess BuLi to create the active surface sites for LASIP in toluene as the solvent. With THF as the reaction medium, the BuLi was found to react not only with the vinyl groups of the styrene derivative but also with the siloxane groups of the substrate. It was found that even under optimized reaction conditions, LASIP from silica and especially from flat surfaces could not be performed in a reproducible manner. Free silanol groups at the surface as well as the ever-present impurities adsorbed on silica, impaired the anionic polymerization. However, living anionic polymerization behavior was found and the polymer load increased linearly with the polymerization time. Polystyrene homopolymer brushes as well as block copolymers of poly(styrene-f)lock-MMA) and poly(styrene-block-isoprene) could be prepared. 

Recently, Quirk and Mathers [264] performed LASIP of isoprene on silicon wafers. A chlorodimethylsilane-functionalized diphenylefhene (DPE) was coupled onto the surface and lithiated with n-BuLi to form the initiating species. The living poly(isoprene) (PI) was end- functionalized with ethylene oxide. A brush thickness of 5 nm after two days of polymerization (9.5 nm after four days) was obtained in contrast to a polymer layer thickness of 1.9 nm by the grafting onto method using a telechelic silane functionahzed PI. 

A piezoelectric pump is constructed with two glass plates and a silicon wafer [22]. A pressure chamber and a raised flat surface suspended with a thin diaphragm are formed on the upper glass plate (Fig. 3). The piezoelectric actuator is placed on the raised flat surface. In order to guide the flow of the pumped liquid, two check valves made of poly-silicon are fabricated on the silicon wafer... 

Only recently first reports appeared describing the potential of the nanostructured thin block copolymer films for lithographic etching. A thin film of polystyrene-block-polybutadiene with a hexagonal cylindrical morphology where the poly-(butadiene) cylinders were oriented perpendicular to the substrate was deposited on a silicon wafer and selectively decomposed by treatment with ozone or converted with osmium tetroxide. By a subsequent reactive ion etching process the pattern could be inscribed into the surface of the silicon wafer yielding small holes or islands with a lattice constant of 27 nm and hole/island sizes of 13 nm [305,312]. 

Polymer films, e.g., poly((V-hydroxysuccinimidyl methacrylate) (PNHSMA) [68], are prepared by spin-coating polymer solutions in a suitable solvent (here DMSO with a typical concentration between 10 and 20 mg/ml) onto clean silicon wafers. To remove traces of the solvent, the films are dried in vacuum for several days. Some of the sample is immersed in PBS buffer for swelling time of 100 min, followed by rapid drying of the surface in a gentle stream of nitrogen. For the determination of... 

A silicon wafer that has one surface oxidized to a controlled depth is coated (on the oxide surface) with a photoresist, such as poly(vinyl cinnamate), to produce a thin and uniform coating several micrometers thick when dry. Exposure to UV light through a mask insolubilizes part of the polymer. The uncross-linked polymer is washed off solvents. The bare substrate parts that thus reappear are etched through the oxide layer down to the silicon layer by a fluoride solution in water or by a plasma that contains reactive ions. 

Broadhead and Tresco studied the effects of fabrication conditions on the structures and performances of membranes formed from poly(acrylonitrile-vinylchloride) (PAN-PVC) by using the phase inversion process [85]. They reported the relationship of the fine-surface structure of PAN-PVC membranes to the membrane performance and membrane fabrication method. The fine-surface structure of nodular elements and the size of these elements could be altered by changing the precipitation conditions. Membranes were prepared at 22 on 55 mm diameter polished silicon wafers by spinning at 1500 rpm for 20 s with a spin coater [86]. The film was immediately precipitated in one of the four different precipitation media. The first three media consisted of deionized water at 4,22, and 54 °C. These membranes were referred to as Type 1 , Type 2 , and Type 3 , respectively. The fourth medium was a 50/50 mixture of deionized water and N,iV-dimethylformamide (DMF) at 54 °C and coded as Type 4 . Figure 4.53 shows the histograms of the nodule size distributions observed at the skinned surface of the membranes made under four different precipitation conditions. The sizes of these nodular elements became smaller and more uniform with milder precipitation conditions, which supports the theory that nodules are formed through spinodal decomposition under these conditions. In addition, the size of these nodules could be related to water permeability. Hence, water transport occurred through the interstitial spaces where the pores could be situated. 

Here, we employed polymethacrylates to provide the roughened and oxidized surface of aluminium sheets with superhydrophobic properties. Polymethacrylates can be easily synthesized and their properties varied by copolymerization of methacrylate monomers that have different side chains. The correlation between the structural composition of polymethacrylates and their wetting behavior is well known from model studies carried out on thin films on smooth surfaces [19, 20], but there is no information about the wetting behavior of polymethacrylate hlms on micro-rough surfaces. We have synthesized poly(tert-butyl methacrylate) and poly(methyl methacrylate) containing different hydrophobic and hydrophilic sequences. In dependence on the polymer composition the wetting behavior was studied on polymer-coated smooth silicon wafers and rough aluminium surfaces. 

Figure 18.15 shows the schematic of the fabrication process. After oxidation of the double-side polished silicon substrate wafer, a first lower poly-Si layer with a thickness of 45 pm is deposited by means of an epi-poly process. In order to remove spikes and obtain a smooth surface, 5 pm of poly-Si has to be removed by poly-Si CMP. This polishing is a two-step process, consisting of a 5 pm bulk removal by means of a fiimed-silica slurry and a subsequent final polish of several 10 nm with a haze-firee slurry. After deposition and stmcturing of some intermediate layers, a second upper poly-Si layer, again with a thickness of 45 pm, is deposited and subsequendy polished with the same two-step poly-Si CMP process. As this will be the surface of the evaporated silver mirror, a smooth as well as flat surface has to be achieved. After a backside silicon etch and the removal of the sacrificial layer, the scanning mirror device is released, see Figure 18.16(a) and (b). 

Lamellar orientation in thin films of a model diblock copolymer with symmetric poly(styrene)- -PLLA (PS-PLLA) was investigated by Chen et al. [62] in the molten state on silicon wafer supported surfaces. Stretching and compression were apt to induce orientation of PLA. Pluta and Galeski [63] studied the plastic deformation of amorphous and thermally noncrystallizable 70/30 PLA/PDLLA induced by plane strain compression in a channel die. The results revealed that plastic deformation transformed an amorphous PLA or PDLLA (thermally noncrystallizable) into a crystalline fibrillar texture oriented in the flow direction. 

---