Semiconducting wafer

A beta detector consisting of a small semiconducting wafer of CdTe at the outlet of the capillaiy will respond to labeled beta emitters. 1 O M solutions of compounds containing have been reported. 

Chemical-mechanical polishing processes are used in the manufacturing of microelectronic devices to form flat surfaces on semiconducting wafers, field emission displays, and many other microelectronic workpieces. For example, the manufacture of semiconductor devices generally involves the formation of various process layers, selective removal or patterning of portions of those layers, and deposition of yet additional process layers above the surface of a semiconducting workpiece to form a semiconducting wafer (3). 

Figure 13.1. Schematic illustration of processes for fabricating semiconducting wire/ ribbons from bulk wafers.

Separation of SWNTs based on chirality and diameter with surfactants has also been evidenced by density-gradient ultracentrifugation [86]. Finally, a recent study has demonstrated the separation of semiconducting nanotubes from metallic ones by chemical interaction of the former with attached amine-terminated silane molecules assembled on a silicon wafer. In a separate experiment, metallic nanotubes were also... 

Construction of electronic devices usually involves deposition of thin layers of semiconducting, metallic, and insulating materials onto a suitable substrate (which might be a wafer cut from a Czochralski silicon boule with a diamond saw).15-24 In some cases, it is possible to grow crystalline layers onto a substrate such that the crystallographic order of the atoms in the film is related to that of the surface of the substrate this is known as epitaxial growth. 

Details of building specific types of microelectronic devices are well described by Grovenor15 as an illustration, we consider only the chemical techniques involved in making a metallic contact to a silicon wafer surface. Preparation of a wafer of Si or other material and application of epitaxial layers of semiconducting or insulating materials, if required, were outlined in Section 19.2.1. The construction of shaped features on the wafer is usually done by photolithography, or ion- or electron-beam variants thereof. 

Misra and Finnie (1970) investigating the scribing process used for segmentation of semiconducting silicon wafers established the formation of three-crack systems (Fig. 6.2.6) on the lateral surfaces of the plate, chevron cracks develop along the scratch, whereas beneath the scratch,... 

In chemical vapor deposition (CVD), a semiconducting or insulating solid material is formed in a reaction between a gaseous species and a species adsorbed on the surface of silicon wafers (disks about 10 cm in diameter and 1 mm thick). The coated wafers are subjected to further processing to produce the microelectronic chips in computers and most other electronic devices in use today. 

After the photoresist is in place, a layer of conducting, semiconducting, or insulating metal solution is applied to the wafer and adheres in the pattern opposite to the photoresist. The application and removal of photoresist and metal solutions is repeated 10-20 times in the manufacture of a single integrated circuit. In addition to the number of... 

Silicon s most familiar use is in the production of microprocessor chips. Computer microprocessor chips are made from thin slices, or wafers, of a pure silicon crystal. The wafers are doped with elements such as boron, phosphorus, and arsenic to confer semiconducting properties on the silicon. A photographic process places patterns for several chips onto one wafer. Gaseous compounds of metals are allowed to diffuse into the open spots in the pattern, and then the pattern is removed. This process is repeated several times to build up complex microdevices on the surface of the wafer. When the wafer is finished and tested, it is cut into individual chips. 

The most simple pentaeene OTFT test structure used in many labs is based on a Si wafer piece covered with a thermal oxide. Here, the heavily doped Si wafer takes the role of the back gate electrode, and the Si02 takes the role of the gate dielectric. A pentacene thin film is deposited as the semiconducting layer. Source and drain electrodes are deposited either on the silicon oxide (bottom contact) or on top of the pentacene film (top contact). 

Figure 12-12 illustrates one form ofa lithium-drifted detector, which is fashioned from a wafer of crystalline silicon, There are three layers in the crystal a p-type semiconducting layer that faces the X-ray source, a central intrintic zone, and an -type layer. T he outer surface of the p-iype layer is coaled with a thin layer of gold for electrical contact often, it is also covered with a thin beryllium window that is transparent to X-rays. The signal output is taken from an aluminum layer that coats the n-type silicon this output is fed into a preampliftcr vc ith a gain of about 10. The preamplifier is frequently a field-effect transistor that is fabricated as an integral part of the detector. 

Masks and reticles contain the blueprints or the patterns of the circuit elements used as templates in the fabrication of IC devices. They provide the templates of the circuit elements from which numerous replications, perhaps numbering in the millions, are made. The object of lithography is to transfer these blueprints to semiconducting substrates such as silicon wafers. 

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