Screening silicon wafer

The wafers are processed into solar cells, the majority of which have a diode structure, as sketched in Figure 11.4, characterized by a thin, diffused, doped emitter, screen-printed front and back contacts and a front-surface antireflective coating. Prior to the effective cell manufacturing step, a chemical treatment of the silicon wafers removes... 

Australia, and scaled up by BP Solar in Spain, the heterojunction with intrinsic thin layer (HIT) cells developed by Sanyo by replacing the diffused P-doped emitter with an amorphous silicon layer and the back contact cells developed by Stanford University for use in concentrator technology and now converted to a large area for flat plate use. All three use single-crystalline silicon, while the majority of screen-printed cells use multicrystalline silicon wafers. 

Sample integrations similar to pharmaceutical approaches were already examined in 1997 [39]. Here, a chip-like microsystem was integrated into a laboratory automaton that was equipped with a miniaturized micro-titer plate. Microstructures were introduced later [40] for catalytic gas-phase reactions. The authors also demonstrated [41] the rapid screening of reaction conditions on a chip-like reactor for two immiscible liquids on a silicon wafer (Fig. 4.8). Process conditions, like residence time and temperature profile, were adjustable. A third reactant could be added to enable a two-step reaction as well as a heat transfer fluid which was used as a mean to quench the products. 

Symyx, one of the pioneers in combinatorial screening, presented a chemical processing microsystem in 2000 for the screening of 256 catalysts on a silicon or quartz glass wafer [44]. The reactant flow was distributed by a microstructured manifold etched into a silicon wafer (see Bergh, Chapter 3). 

Flego [1] recommends the use of micro devices for automated measurement and microanalysis of high-throughput in situ characterization of catalyst properties. Murphy et al. [5] stress the importance of the development of new reactor designs. Micro reactors at Dow were described for rapid serial screening of polyolefin catalysts. De Bellefon ete al. used a similar approach in combination with a micro mixer [6], Bergh et al. [7] presented a micro fluidic 256-fold flow reactor manufactured from a silicon wafer for the ethane partial oxidation and propane ammoxidation. 

Figure 3.34 Parallel reactor for catalyst screening of wafer-type substrates and silicon wafer supply manifold for the distribution of the reactants to the 256 wells [7]...

Fig. 8.5. Miniaturized biodevices for ultra-high-throughput screening. (A) Piezo-electric ink-jet pipettor that allows pipetting down to the pico-liter scale with speeds up to 10,000 drops per second and an accuracy of 3 % [97] (B) Sample carrier containing six segments of a silicon wafer. Each segment comprises 900 reaction compartments with a maximum volume of 120 nl each [28].

Most experimental reactors are small to ensure large surface-to-volume ratio for good temperature regulation, and to minimize the chemical inventory needed to conduct the experiments. As illustrated in Figures 1.6 and 1.8, flow and batch reactors with volumes of several hundred nanoliters have been fabricated out of silicon wafers and used for organic synthesis screening studies. 

PEG-20 oleamine PEG-35 tallowamine cleaner, polymeric residues Diethyl oxalate Dimethyl adipate N-Methyl-2-pyrrolidone cleaner, precision Dichlorofluoroethane cleaner, printed circuit boards 2-Ethyl-1-butanol cleaner, scouring powders Trisodium phosphate, chlorinated cleaner, semiconductors Nitrogen trifluoride cleaner, silicon wafer industry Dimethyl hexynol cleaner, silk screen stencils Periodic acid Sodium m-periodate cleaner, solvent... 

The use of deformable mirrors to compensate the aberration of astronomical images caused by the turbulence of the earth atmosphere has led to outstanding successes of ground-based astronomy. In collaboration with the Active Structures Laboratory of Bmssels University a demonstrator for a bimorph mirror was developed and manufactured as shown in Fig. 12 It consists of a silicon wafer with a diameter of 150 mm and 0,75 mm thickness as well as 91 honeycomb thick film piezoelectric actuators with 80 pm thickness, which have been screen printed at the backside of the silicon wafer. Each actuator can be driven individually to control the shape of the bimorph mirror and thus optical aberrations. 

In a subsequent publication by the same group, solution nebulization ICP-MS was combined with particle screening and microsampling for analysis of individual particles (Esaka et al. 2013). Two methods were used for locating the uranium-bearing particles fission track analysis (FTA) and automated SIMS (described earlier). The particles were then manipulated inside a SEM and placed on silicon wafers and then dissolved for ICP-MS analysis. After method development and validation with particles from certified reference materials (NBL CRM U050, UlOO and U500) that were smeared on a cotton swab, a real-life sample collected at a nuclear facility was examined by both techniques. The measured ratio of the particles that were... 

New techniques are being applied to develop miniaturized sensor arrays such as screen printing for thick film and electron beam evaporation, thermal vacuum deposition, and pulsed laser deposition for thin-film technique. Microfabrication techniques were used to prepare a sensor array for use in a voltammetric e-tongue by depositing gold (Au), platinum (Pt), iridium (Ir), and rhodium (Rh) on a silicon wafer. 

The reactor system of Zech and co-workers [50, 51] is a good example of an integrated approach as it combines devices from different suppliers witha complex screening system. The reactor was manufactured at IMM and the sampling device was provided by AMTEC, Chemnitz. The catalyst and their preparation method were supplied by the TU Chemnitz. The housing of the reactor module consists of 35 stacked frames which can incorporate the same number of catalyst wafers (Figure 3.18). The modular concept of the reactor allows the use of micro structured catalyst wafers made of different materials such as metals, ceramics, silicon and glass. 

One of the means to make systems with such characteristics is to use microfabrication methods that make many components in parallel. The prime example is of course all methods involving lithography on planar substrates such as glass, silicon, or ceramics. Another example of such a technique is screen printing. Some techniques are used on entire wafers, but not in parallel laser drilling, for instance. 

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