Lithography techniques

The top microfluidic architecture was fabricated using a multilayer soft lithography technique with polydimethylsiloxane (PDMS). In the figure, we illustrate a... 

The ability to make ever smaller solid-state devices by improved lithography techniques has led to the development of so-called beam lead Schottky-barrier diode detectors and mixers in which diodes are fabricated by the same techniques used to make integrated circuits, and for this reason, they can be included in these circuits. Figure 7 shows such a beam-lead detector/mixer made by Virginia Diodes of Charlottesville, VA [15]. This same configuration is used in fabricating the varactor devices used for frequency multiplication discussed in the preceding section. 

Polysiloxanes are apparently the materials of choice in the new soft-lithography techniques.376 380 The method is outlined briefly in Figure 4.20. In the first step, linear (liquid) PDMS is poured over the surface of the master to be reproduced. It is then cross linked, and peeled away from the master surface. The PDMS surface containing the pattern is then coated with a hydrophobic alkane thiol, and the pattern transferred to a... 

A final mention should be made of the use of polysiloxanes in the area of microfluidics.377 381 Devices of this type have to have channels or capillaries with dimensions 10-10,000 pm, and their preparation is relatively straightforward with PDMS, using the soft-lithography techniques just described to make the required molds. 

Fluorescence burst analysis, a variation of FCS procedures that has an optimum configuration for simple presentation, uses a uniform nanoscopic flow channel with an optically perfect ceiling, uniform cross section, and periodic electrodes that can now be constructed by careful electron lithography techniques.55 By application of controlled electric fields, uniform plug flow of solution through... 

Modern lithography techniques can be used to make many submicrometer windows on the sample. The sample can then be thinned to obtain many small transparent regions. The advantage is that if lithography facilities are available, several regions of the specimen can be analyzed simultaneously for statistical sampling. 

An SFM based lithography technique by means of mechanical interactions as applied to surfaces of polystyrene (PS) and polymethylmethacrylate (PMMA) is described in Sect. 6. Similarly, some results of SFM-based poling experiments performed on a piezoelectric polymer are elucidated in Sect. 7.6. 

Dynamic plowing lithography (DPL), i.e. the lithography technique in tapping mode in which the force between tip and sample is increased by suddenly increasing the amplitude of the cantilever oscillations, has been developed by Klehn and coworkers [257-260]. The topography of the sample is acquired with a normal, small amplitude of the cantilever oscillations. When the amplitude is increased, the feedback makes the sample approach to the tip, in order to keep constant the oscillation amplitude, and the tip indents the sample. 

Combining this self-assembled monolayer chemistry with AFM tip apparatus yields a new AFM-based soft lithography technique, which is often called dip-pen nanohthography (Fig. 4.42). It can be used to write very line patterns on metal and semiconductor surfaces using a solution of monolayer-forming materials as ink. 

Lithography techniques such as nanosphere lithography and electron-beam lithography are ideal methods to fabricate the reproducible SERS substrates [51]. They have been shown to improve the substrates performance by controlling the size and shape of colloidal nanoparticles and interparticle spacing [52]. Lithography techniques are simple to implement and of low cost. These advantages make them suitable platforms for the fabrication of SERS-active substrate. 

Pattern fabrication is an important issue in many fields ranging from microelectronics to biological microarray production and nanotechnology.64 Soft and probe lithography techniques such as microcontact printing (pCP) and dip-pen nanolithography (DPN) are frequently used to pattern surfaces.65 Conventional pCP is an efficient and... 

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