Properties multilevel

Tannor D J and Rice S A 1987 Photon echoes in multilevel systems Understanding Molecular Properties ed J Avery et al (Dordrecht Reidel) p 205... 

Oxidation of Silicon. Silicon dioxide [7631-86-9] Si02, is a basic component of IC fabrication. Si02 layers are commonly used as selective masks against the implantation or diffusion of dopants into silicon. Si02 is also used to isolate one device from another. It is a component of MOS devices, and provides electrical isolation of multilevel metalliza tion stmctures (12). A comparison of Si and Si02 properties is shown in Table 1. 

Polysilicon. Polysihcon is used as the gate electrode material in MOS devices, as a conducting material for multilevel metallization, and as contact material for devices having shallow junctions. It is prepared by pyrolyzing silane, SiH, at 575—650°C in a low pressure reactor. The temperature of the process affects the properties of the final film. Higher process temperatures increase the deposition rate, but degrade the uniformity of the layer. Lower temperatures may improve the uniformity, but reduce the throughput to an impractical level. 

Additional drawbacks to the use of polyimide insulators for the fabrication of multilevel structures include self- or auto-adhesion. It has been demonstrated that the interfacial strength of polyimide layers sequentially cast and cured depends on the interdiffusion between layers, which in turn depends on the cure time and temperature for both the first layer (Tj) and the combined first and second layers (T2) [3]. In this work, it was shown that unusually high diffusion distances ( 200 nm) were required to achieve bulk strength [3]. For T2 > Tj, the adhesion decreased with increasing T. However, for T2 < Tj and Tj 400 °C, the adhesion between the layers was poor irrespective of T2. Consequently, it is of interest to combine the desirable characteristics of polyimide with other materials in such a way as to produce a low stress, low dielectric constant, self-adhering material with the desirable processabiHty and mechanical properties of polyimide. 

Pinhole density is another property of interest in defining insulation integrity. It was indirectly assessed from the number of shorts in a statistical number of probed die where the die was a multilevel test structure consisting of TiWAu-polyimide-TlWAu with 3275 crossovers of first and second metal per die. The results indicated that the probability of a short in a crossover for 1.2 y thick PI2545 was 1 in 133,333. 

The formulation of a single-layer resist that can meet beyond-state-of-the-art demands is an arduous task. To date, very few such materials have been advertized, and their field performance is yet to be proven. The difficulty lies in the fact that requirements of sensitivity, etch resistance, and planarization are mutually exclusive. For example, thinner resists capable of higher resolution sacrifice substrate etching protection and planarization. Consequently, the focus of lithographers lately has centered upon multilevel-resist processes that distribute desirable resist properties among several different organic and inorganic layers. 

Component failure is so crucial that Caterpillar does not trust any other company to make these rubber products—not even Goodyear or Firestone. Caterpillar makes its own rubber component formulations. Rubber component failure is a multilevel issue performance depends on the rubber parts, which depend on the rubber component-based materials. This, in turn, depends on the failure mechanics properties of these materials, which are affected by rubber curing chemistry. In the end, the design- and manufacturing-related issues depend on quantum chemistry of sulfur links. This is another problem in which the transformation process goes from molecules to materials to market and has the proverbial brick wall in between. 

As the size of microchips evolves from 130nm to 90nm or smaller, the increasing packing density between multilevel interconnects will lead to severe RC delay, power consumption and wire cross talk, which are the major factors limiting device performance. As a consequence, the design of novel semiconductor materials with desired chemical and physical properties has stimulated intense experimental and theoretical efforts. For example, there have been ongoing activities to develop materials with low dielectric constants (k) to replace the current silicon dioxide (k = 4.0) wire insulator. A particularly active area of research in the past few... 

Polyimide films are extensively used in the microelectronic industry as insulators for multilevel interconnect systems because of their excellent thermal and electrical properties. In some cases,... 

In addition to the construction of a multilevel interconnect network, the semiconductor industry also improves the performance of IC chips by incorporating low-resistivity metal wiring such as copper and new dielectric materials with lower k constant (see Section 1.3.1 for details). The added benefit of using low-fc dielectric materials includes a reduction in the crosstalk [29-31] and power dissipation [29-33]. The key challenge for the implementation of low-fc materials is related to their intrinsic weak mechanical properties. Furthermore, in order to achieve a k value below 2.2, practically all materials are made with pores that exacerbate mechanical stability issue [29-33]. This is a particular concern for the CMP community as the operation invariably involves mechanical stress and shear force. In addition, practically all low-fc dielectric materials are hydrophobic in nature. Lfpon exposure to moisture or wetness, the dielectric constant tends to increase. Therefore, unlike silicon-dioxide-based dielectric, the effective k constant may change after CMP. To... 

T. Homma, Properties of fluorinated silicon oxide films formed using fluorotriethoxysilane for interlayer dielectrics in multilevel interconnections, J. Electrochem. Soc. 143, 1084, 1996. 

Lykken DT 1957 A study of anxiety in the sociopathic personality. J Abnorm Soc Psych 55 6—10 Lykken DT, Katzenmeyer C 1973 Manual for the activity preference questionnaire (APQ). In Psychiatric research reports. University of Minnesota Press, Minneapolis, MN McKeen Cattell J 1890 Mental tests and measurements. Mind 15 373—380 Messick S 1992 Multiple intelligences or multilevel intelligence Selective emphasis on distinctive properties of hierarchy On Gardner s Frames of mind and Sternberg s Beyond IQ in the context of theory and research on the structure of human abilities. Psych Inquir 3 365-384... 

Aromatic polyimides have gained wide popularity as dielectric materials in a variety of applications in the manufacturing of electronic circuits due to their thermal, mechanical and electrical properties. Most notable among these applications are as interlayer dielectrics in multilevel VLSI circuits and in multilevel interconnects, as well as in the packaging of integrated circuits. 

The dielectric properties of two different thermoset films derived from bis-benzocyclobutene monomers were described. The dielectric constant was 2.65 + 0.1. The dissipation factor was below 0.001 above 1.0 kHz. These values are significantly lower than those reported for polyimide thin films. Therefore, the BCB films described in this work are attractive candidates for interlevel dielectrics in dense multilevel interconnection structures. 

The interest in quantum interference stems from the early 1970s when Agarwal [4] showed that the ordinary spontaneous decay of an excited degenerate V-type three-level atom can be modified due to interference between the two atomic transitions. The analysis of quantum interference has since been extended to other configurations of three- and multilevel atoms and many interesting effects have been predicted, which can be used to control optical properties of quantum systems, such as high-contrast resonances [5,6], electro-magnetically induced transparency [7], amplification without population inversion [8], and enhancement of the index of refraction without absorption [9]. 

Although the trapping states have the common property that the population will stay in such a state for an extremely long time, they can be implemented in different ways. In a multilevel system the population can be trapped in a linear superposition of the bare atomic states, or in a dressed state corresponding to an eigenstate of the atoms plus external fields, or in some cases, in one of the excited states of the system. 

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