This extended Poole-Frenkel model includes the effects of compensation. The relative densities of donor and acceptor sites control the slope of the log J vs E1/2 plots. With only one type of site present, the slope equals that expected for Schottky emission [slope= (e3/πεε0)1/2/2kT]. When sites of the opposite type compensate, the slope doubles. The degree of compensation must be known to determine the barrier heights separating the emission site from the band edge. Data from metal-silicon nitride-metal devices are consistent with this model with emission occurring from impurity sites approximately 2.0 eV from the conduction band edge.

Thin film silicon nitride deposited from the reaction of silane and ammonia exhibits reproducible current characteristics at high fields less than breakdown. Conduction behavior with thickness is similar for films from 60 to 1600A on quartz and silicon substrates. A large temperature dependence, a linear variation of In ! with V 1/2, and no electrode dependence indicate thermal emission from the bulk as the dominant injection mechanism at room temperature.Insulating films conduct a small current before destructive breakdown occurs. The characteristics of this current indicate the reproducibility of the films and help design devices with regard to leakage and breakdown. This paper reports results of a study of the conduction properties of silicon nitride films deposited from the reaction of silane and ammonia. Figure 1 shows the system used for depositing the films. Table I describes the deposition cycle. Film DepositionThe Matheson Company furnishes the semiconductor-grade silane and ammonia. The hydrogen is commercial grade. The quartz reaction chamber with vertical flow uses a resistive-heated graphite substrate holder. After flowing over the heated substrate, the excess gases are burned and vented via a hood. A chromel-alumel thermocouple measures the temperature of the top of the substrate.Substrates are metal-coated quartz and polished silicon. Metals used for the base contact are Mo, Ni, and Pt. The silicon is 0.01 ohm-cm p-type mechanically polished with a 10-sec etch in 48% HF just before placing in the reaction chamber. Vapor degreasing in trichloroethylene cleans the metals. An electron gun at a pressure of 10 -9 Torr evaporates the molybdenum. All other metals are evaporated from tungsten filaments at a pressure of 10 -6 Torr. After film deposition the top electrode of A1 or Au is evaporated through a metal mask at 10 -6 Tort.A break in the film growth-rate curve shown in Fig. 2 occurs at an ammonia to silane ratio of 7: 1. Bean (1) and others attribute this break to the film becoming silicon rich. Deposition temperature is approximately 700~ for all films. An x-ray diffractometer reveals no structure of the films which are transparent and apparently amorphous. Thickness DeterminationThe thickness determination used capacitance measurements and the color of the interference fringes. A value of 2.0 for the index of refraction (1, 2) in the color determination seemed appropriate. The dielectric constant was determined as 5.5 from a series of devices as shown in Fig. 3. The error in thickness from color determination averages out with the several thicknesses and devices used. This value of dielectric constant was used to determine thickness of the very thin films. The capacitance readings are stable to 5 significant figures on metal-nitride-metal devices with zero bias. Conduction PropertiesFigures 4 and 5 show the conducting properties for a series of MIM and MIS devices with thicknesses ranging from 1600 to 60A. Curve (a) is from a film on a molybdenum-coated quartz substrate. The rest are from films o...

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Dopant deactivation and thermal annealing characteristics of metal-oxide-semiconductor capacitors fabricated on Ge/B-doped silicon after gamma irradiation or Fowler–Nordheim injection were investigated for the first time. A decrease of about 30% in active acceptor concentration was observed immediately after gamma irradiation or Fowler–Nordheim injection. Further deactivation of boron (∼20%) occurred with annealing for temperatures of 80 °C and higher. Hydrogen for the deactivation, which occurred during annealing, is thought to come from dissociation of weakly bonded Ge—H formed during the gamma irradiation or Fowler–Nordheim injection. Capacitors fabricated on conventional boron-doped substrates do not exhibit acceptor deactivation as a result of annealing following irradiation or injection. For annealing temperatures of 110 °C and higher, the boron is first deactivated by the process noted above, and then is apparently reactivated by the dissociation of B—H bonds with hydrogen evolution from the structure.

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