Photolithographic fabrication

Figure 8.13 Sequence of photolithographic fabrication (a) Cr- and Au-masked glass plate coated with photoresist, (b) plate exposed to light through a master mask, (c) photoresist developed, (d) exposed metal mask etched, (e) exposed glass etched, (f) resist and metal stripped, and (g) glass cover plate bonded to form capillary. (Reprinted from Ref. 54 with permission.)...

Rogers J A, Bao Z and Raju V R, Non-photolithographic fabrication of organic transistors micron feature sizes , Appl Phys Lett, 1998 72 2716-2718. 

Nanostracturing processes for silicon Photolithographic fabrication X-ray lithography [130] Electron beam lithography [139] Chemical etching [140] Physical and chemical vapor deposition [141]... 

Stacked planar optics consists of planar optical components in a stack, as shown in Fig. 28. All components must have the same two-dimensional spatial relahonship, which can be achieved from planar technology with the help of photolithographic fabrication, as used in electronics. Once we align the optical axis and adhere all of the stacked components, two-dimensionally arrayed components are realized the mass production of axially aligned discrete components is also possible if we separate individual components. This is the fundamental concept of stacked planar optics, which may be a new type of integrated optics. 

Doan VV, Sailor MJ (1992a) Photolithographic fabrication of micron-dimension porous Si structures exhibiting visible luminescence. Appl Phys Lett 60(5) 619-620 Doan VV, Sailor MJ (1992b) Luminescent color image generation on porous silicon. Science 256(5065) 1791-1792... 

The microfluidic chip system for preparing a miniaturized PMBV/PVA hydrogel consists of a two-chamber chip, an aluminum custom-made chip holder, Teflon capillaries, microtubes, and syringes equipped with a microsyringe pump (Fig. 15). The two-chamber chip was fabricated by a photolithographic wet etching technique. Whereas both channels and chambers (200 pm in depth) were fabricated on the top plate, only chambers (200 pm in depth) were fabricated on the bottom plate. 

DNA arrays are fabricated by immobilizing the complementary DNA (cDNA) onto a solid substrate such as silicon, nylon or glass. This can be achieved by robotic printing of polymerase chain reaction (PCR) products (also known as direct-deposition approach), photolithographical synthesis of complementary oligonucleotides or piezoelectric inkjet printing of PCR products (also known as indirect-deposition approach). 

As the analytical, synthetic, and physical characterization techniques of the chemical sciences have advanced, the scale of material control moves to smaller sizes. Nanoscience is the examination of objects—particles, liquid droplets, crystals, fibers—with sizes that are larger than molecules but smaller than structures commonly prepared by photolithographic microfabrication. The definition of nanomaterials is neither sharp nor easy, nor need it be. Single molecules can be considered components of nanosystems (and are considered as such in fields such as molecular electronics and molecular motors). So can objects that have dimensions of >100 nm, even though such objects can be fabricated—albeit with substantial technical difficulty—by photolithography. We will define (somewhat arbitrarily) nanoscience as the study of the preparation, characterization, and use of substances having dimensions in the range of 1 to 100 nm. Many types of chemical systems, such as self-assembled monolayers (with only one dimension small) or carbon nanotubes (buckytubes) (with two dimensions small), are considered nanosystems. 

The fabrication method generates functional elements via anisotropic etching of high-quality semiconductor wafers, referred to as mother wafers.13 17 25 The process begins with photolithographic definition of patterns... 

The high selectivity of wet etchants for different materials, e.g. Al, Si, SiOz and Si3N4, is indispensable in semiconductor manufacturing today. The combination of photolithographic patterning and anisotropic as well as isotropic etching of silicon led to a multitude of applications in the fabrication of microelectromechanical systems (MEMS). 

The membranes of the microhotplates were released by anisotropic, wet-chemical etching in KOH. In order to fabricate defined Si-islands that serve as heat spreaders of the microhotplate, an electrochemical etch stop (ECE) technique using a 4-electrode configuration was applied [109]. ECE on fully processed CMOS wafers requires, that aU reticles on the wafers are electrically interconnected to provide distributed biasing to the n-well regions and the substrate from two contact pads [1 lOj. The formation of the contact pads and the reticle interconnection requires a special photolithographic process flow in the CMOS process, but no additional non-standard processes. 

Methods have been developed for fabrication of the highly-ordered titania nanotuhe arrays from titanium thin films atop a substrate compatible with photolithographic processing, notably silicon or FTO coated glass [104]. The resulting transparent nanotuhe array structure, illustrated in Fig. 5.16, is promising for applications such as anti-reflection coatings and dye sensitized solar cells (DSSCs). Fig. 5.17 shows the typical anodization behavior of a 400 nm Ti thin film anodized at 10 V in an HE based electrolyte. Eor a fixed HE concentration, the dimensions of the tube vary with respect to... 

II), effective at 193 nm were prepared by the authors (1,2), respectively, and used in the fabrication of semiconductor devices by photolithographic techniques. 

---