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Abstract: Standard IC processes, as well as those involving the use of ionizing radiation, such as x-ray lithography etc., result in the generation of bulk defects, and interface states in the gate insulator, or underlying substrate, respectively, of insulated gate field effect transistors. Bulk defects are believed to be present as positively and negatively charged electron and hole traps, respectively, as well as neutral hole and “large” and “small” neutral electron traps. This paper provides a perspective of the current state of knowledge about the spatial distributions of large bulk defects, their areal densities, sizes, possible interrelationships among them, and the special cases of defects created by ion implanted silicon and oxygen, where knock-on effects have been simulated. It appears that bulk defects may all have their origin in neutral hole traps, (so-called E′ centers) and that when the insulator thickness is decreased to about 6-7 nm, defects are either no longer present, or, more likely, are incapable of trapping charge at room temperature because trapped carriers can either tunnel to one of the interfaces, or be annihilated by a reverse process. It appears possible also that the precursor of the several types of defects only forms at a “grown” silicon-silicon oxide interface. In theory, this would make it possible to grow defect free insulators by a combination of deposition and oxidation processes.

Abstract: The gas phase reaction of Zn and H2O in a He carrier gas has been used as the basis for the chemical vapor deposition of ZnO on sapphire and MgAl spinel. Deposit characteristics were studied as a function of reactor linear gas stream velocity, Zn/H2O vapor phase ratio, temperature and substrate preparation. It was round that the substrate support can influence the surface morphology significantly and that in situ pretreatment can affect epitaxial relationships between deposit and substrate. Transparent, visually smooth deposits of (11–24) ZnO can be obtained on chemically polished (0001) sapphire at 815�C using average linear gas stream velocities, ν, of 6-12 cm/sec referenced to room temperature in conjunction with a Zn/H2O reactor input-pressure ratio of 0.02–0.09 (using Zn reactor pressures of 1.2–5.0 � 10−3 atm) . The substrates are given an H2O in situ pretreatment at 900�C prior to deposition at ν = 3 cm/sec with the partial pressure of H2O in He = 5.7 � 10 atm.

Using a gas transpiration method, the equilibrium constant for the reaction ZnO(s) + H2(v)⇄ Zn(v) + H2O(v) was determined directly in the temperature interval 592–950°C. The data are described by the equation log10K = [-11.794 × 103/T] + 8.040 with ΔH° = 53.97 Kcal/mole and ΔS° = 36.79 e.u. Based on this Information, vapor-solid gas concentration curves useful for defining conditions for the chemical vapor transport of ZnO via the reverse of the above reaction have been computer calculated.