VLSI

Nijnieijer, M.C, Boer, M.A. Correction of lens-distortion for real-time image processing systems. VLSI Signal Processing VI... 

Moore G 1980 VLSI, what does the future hold Eiectron. Aust. 42 14... 

Impurity Commercial, ppmv VLSI, ppmv Megaclass, ppmv... 

Dielectric Film Deposition. Dielectric films are found in all VLSI circuits to provide insulation between conducting layers, as diffusion and ion implantation (qv) masks, for diffusion from doped oxides, to cap doped films to prevent outdiffusion, and for passivating devices as a measure of protection against external contamination, moisture, and scratches. Properties that define the nature and function of dielectric films are the dielectric constant, the process temperature, and specific fabrication characteristics such as step coverage, gap-filling capabihties, density stress, contamination, thickness uniformity, deposition rate, and moisture resistance (2). Several processes are used to deposit dielectric films including atmospheric pressure CVD (APCVD), low pressure CVD (LPCVD), or plasma-enhanced CVD (PECVD) (see Plasma technology). 

The physical techniques used in IC analysis all employ some type of primary analytical beam to irradiate a substrate and interact with the substrate s physical or chemical properties, producing a secondary effect that is measured and interpreted. The three most commonly used analytical beams are electron, ion, and photon x-ray beams. Each combination of primary irradiation and secondary effect defines a specific analytical technique. The IC substrate properties that are most frequendy analyzed include size, elemental and compositional identification, topology, morphology, lateral and depth resolution of surface features or implantation profiles, and film thickness and conformance. A summary of commonly used analytical techniques for VLSI technology can be found in Table 3. 

Table 3. Analytical Techniques Used in VLSI Technology...

Electron Beam Techniques. One of the most powerful tools in VLSI technology is the scanning electron microscope (sem) (see Microscopy). A sem is typically used in three modes secondary electron detection, back-scattered electron detection, and x-ray fluorescence (xrf). AH three techniques can be used for nondestmctive analysis of a VLSI wafer, where the sample does not have to be destroyed for sample preparation or by analysis, if the sem is equipped to accept large wafer-sized samples and the electron beam is used at low (ca 1 keV) energy to preserve the functional integrity of the circuitry. Samples that do not diffuse the charge produced by the electron beam, such as insulators, require special sample preparation. 

N. G. Einspmch, ed., VLSI Electronics Microstructure Science, Vol. 8 Plasma Processingfor VLSI, Aca demic Press, Inc., Orlando, Fla., 1984. 

S. K. Ghandhi, VLSI Fabrication Principles, ]ohn Wiley Sons, Inc., New Yoik, 1983. 

Fig. 1. Technological trends A, components per chip B, minimum feature length , metal oxide semiconductor (MOS) memory A, bipolar memory I MOS logic n, bipolar logic. The designations SSI, MSI, LSI, and VLSI stand for small-, medium-, large-, and very large-scale iategration, respectively.

For example, chloride and duoride ions, even in trace amounts (ppm), could cause the dissolution of aluminum metallization of complimentary metal oxide semiconductor (CMOS) devices. CMOS is likely to be the trend of VLSI technology and sodium chloride is a common contaminant. The protection of these devices from the effects of these mobile ions is an absolute requirement. The use of an ultrahigh purity encapsulant to encapsulate the passivated IC is the answer to some mobile ion contaminant problems. 

Although the majority of NAA applications have been in the area of bulk analysis, some specialized uses need to be mentioned. One such unique application is the measurement of phosphorus in thin films (about 5000 A) of phosphosilicate (PSG) or borophosphosilicate (BPSG) glasses used in VLSI device fabrication. In this case,... 

Tuckerman D, Pease RFW (1981) High performance heat sinking for VLSI. IEEE Electron Device... 

Ozawa M, Akagawea K, Sakaguchi T (1989) Flow instabilities in paraUel-channel flow systems of gas-liquid two-phase mixtures. Int 1 Multiphase Flow 15 639-657 Peles YP (1999) VLSI chip cooling by boiling-two-phase flow in micro-channels. Dissertation, Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa Peles YP, Yarin LP, Hetsroni G (2001) Steady and unsteady flow in heated capUlary. Int J Multiphase Flow 22 577-598... 

HANDBOOKOF VLSI MICROLITHOGRAPHY edited byWilliamB.GIendinning and John N. Helbert... 

Another disadvantage is that fragile substrates used in VLSI, such as some III-V and II-VI semiconductors materials, can be damaged by the ion bombardment from the plasma, particularly if the ion energy exceeds 20 eV. In addition, the plasma reacts strongly with the surface of the coating as it is deposited. This means that the deposition rate and often the film properties depend on the uniformity of the plasma. Areas of the substrate fully exposed will be more affected than the more sheltered ones. Finally, the equipment is generally more complicated and more expensive. 

Selective deposition, via plugs and gate electrodes for very large scale integrated circuits (VLSI). 

Murarka, S. P., Silicides for VLSI Applications, Academic Press(1983)... 

Deposition of Refractory Metal Silicides for VLSI Metallization, Technology, pp. 79-84 (Feb. 1989)... 

Elliott, J. K., Current Trends in VLSI Materials Part II, Semiconductor International,. 150-153 (April 1988)... 

Smith, P. M., et al., Chemical Vapor Deposition of Ternary Refractory Nitrides for Difiusion Barrier Applications, Proc. 13th. Int. Conf. on VLSI Multilevel Interconnections, Sandia National Labs., Albuquerque, NM (1996)... 

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