Semiconductor industry, design

Generally, epitaxial films have superior properties and, whenever possible, epitaxial growth should be promoted. The epitaxial CVD of silicon and III-V and E-VI compounds is now a major process in the semiconductor industry and is expected to play an increasingly important part in improving the performance of semiconductor and optoelectronic designs (see Chs. 13-15). 

Until about the 1970s, much of the CVD equipment for semiconductor applications was designed and built in-house and a CVD equipment industry was still embryonic. Since then, there has been a considerable shift to standardized systems built by specialized equipment manufacturers particularly for the semiconductor industry, and today sophisticated production and test equipment is readily available. 

Field-effect transistors (FETs) have dominated the semiconductor industry, largely displacing the earlier bipolar junction transistor (BJT) because of its negligible gate current and convenience in the design of integrated circuits. Figure 29 sketches how an FET works. 

System installation in a permanent location may require a sample conditioning system featuring some degree of automation, such as automatic cleaning (the system illustrated above features such a system) and outlier sample collection and the need to interface to an existing control system process computer. The latter may require that the system operates with a standardized communications protocol, such as Modbus, for the chemical industry. Certain specialized industries use different protocols, such as the semiconductor industry, which uses SECS and SEC-11 protocols. A standardized approach designated the Universal Fieldbus is another method/protocol for process analyzers which is being supported by certain hardware manufacturers. 

Orbital motion offers the capability of achieving high relative velocities without sacrificing tool footprint. This point is especially important as the semiconductor industry prepares to make the transition to 300-mm wafers. Several CMP tool concepts have been developed based on orbital motion. Some orbit the carrier while rotating the platen [13]. Others orbit the polishing pad while rotating the carrier [14]. Another design involves orbital (as well as arbitrary nonrotational) motion on a fixed polish pad [15]. 

The design of the first commercial modules has allowed the commercial application of membrane contactors for some specific operations. This is the case of the Membrana-Charlotte Company (USA) that developed the LiquiCel modules, equipped with polypropylene hollow fibers, for the water deoxygenation for the semiconductor industry. LiquiCel modules have been also applied to the bubble-free carbonation of Pepsi, in the bottling plant of West Virginia [18], and to the concentrations of fruit and vegetable juices in an osmotic distillation pilot plant at Melbourne [19]. Other commercial applications of LiquiCel are the dissolved-gases removal from water, the decarbonation and nitrogenation in breweries, and the ammonia removal from wastewater [20]. 

Here we start to examine the pivotal role that polyoxometalate clusters can play in the development of nanoscale devices that utilize POM components, and start to conceptualize some example systems in which POM components could have a crucial role [13, 19]. This is because such functional nanosystems can exploit the building block principle already established in this area of chemistry, coupled with the range of physical properties, and the fact that POM systems can really be seen as molecular metal oxides [20]. To demonstrate this point, a number of examples have been selected across the area of POM chemistry, including our contributions, to help highlight new directions and concepts. It should also be noted that metal oxides already play an important role in the electronics and semiconductor industry today and their solid-state properties have been studied extensively [21, 22]. Many of these concepts are not new in isolation, but the possibility of using molecular design in metal oxides to produce... 

Figures 2 and 3 show that the DRAM chip perforMance has been iMproved even though the chip functionality has increased for the accelerated tests used by the seMiconductor industry. The 85 C/85X RH results are better because of a coMbination of iMproveMents in the chip design, the Manufacturing procedures and the epoxy encapsu-lent. The teMperature cycle test results, however, were priMarily improved by converting to a "low stress" epoxy encapsulant. The im-proveMent in the pressure cooker and the 125 C operating life (Figure 3) was also due to a coMbination of iMproveMents, including those in the epoxy encapsulant. These iMproveMents in device reliability are especially reMarkable when it is realized that the chip susceptibility to contaminants and stress has increased tremendously due to the 60-fold increase to functionality.

The spectacular success of the semiconductor industry is based on the production of materials selectively designed for specialized applications in electronic and optical devices. By carefully controlled doping of semiconductors with selected impurities—electron donors or electron acceptors—the conductivity and other properties can be modulated with great precision. Fig. 12.8 shows schematically how doped semiconductors work. In an intrinsic semiconductor (a), conducting electron-hole pairs can only by produced by thermal or photoexcitation across the band gap. In (b), addition of a small concentration of an electron donor creates an impurity band just below the conduction band. Electrons can then Jump across a much-reduced gap to the conduction band and act as negatively-charged current carriers. This produces a n-type semiconductor. In (c), an electron acceptor creates an empty impurity band just above the valence band. In this case electrons can jump from the valence band to leave positive holes. These can also conduct electricity, since electrons falling into positive holes create new holes, a sequence... 

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