Silicon nitride illustration

Experiments like those described above have been performed to evaluate sodium ion barrier properties of Hitachi PIQ and DuPont PI 2540 polyimide films. Also included in the comparison were silicon nitride coatings plasma deposited in both tensile and compressive stress modes. The structure of the samples is illustrated in Figure 9. N-type, (111) oriented silicon substrates were cleaned and oxidized in dry oxygen ambient at 1100°C to form a 1060 A Si02 film. Wafers intended for polyimide characterization were coated with an organic silane film (gamma glycidal amino propyl trimethoxysilane) to promote adhesion of the polyimide to the oxide surface. The polyimide resins were spun onto the wafers at speeds to produce final... 

Figure 8.1.12 shows a schematic illustration of laser-induced CVC (63). For the synthesis of silicon nitride, the reaction between silane (SiH,) and ammonia... 

Efii and E are the band gaps of the two materials ( qi being the larger) and AE. and AEy are the band offsets. For the nitride overlayers, the sum on the right hand side agrees with the silicon nitride band gap of 5.3 eV within about 0.2 eV, which is as accurate as can be expected for this type of measurement. The conduction band offset is nearly twice that of the valence band and the interface is illustrated in Fig. 9.18. 

Figure 3.40 Calculated phase velocity of flexural plate waves vs ratio of plate thickness, d, to wavelength. A, for silicon nitride. Material is assumed to have the elastic properties of Si3N4 and no residual tension. The mode shapes ate illustrated at the right with a greatly enlarged vertical scale for clarity. Ellipses at left show the retrograde elliptical particle motions of the lowest S3rmmetric and antisymmetric modes for d/A = 0.03. (Reprinted with pemtission. See Ref. (621.)...

Figure 13.2 illustrates the cross section of a representative patterned wafer design for the evaluation of a direct STI CMP process or consumables such as slurry and pad. An ideal STI process should remove all overburden oxide and stop at the silicon nitride layer without any dishing and nitride loss, as shown in Fig. 13.3. Figure 13.4 is a representative STI patterned wafer layout [9]. 

The scanning electron microscope (SEM) in Fig. 13.10a shows the representative results after HSS BKM 2. The SEM image in Fig. 13.10a was taken just after CMP and illustrates minimal dishing and SiN loss. The SEM in Fig. 13.10b was taken after the silicon nitride strip. It shows that the isolated oxide is more than 500 A above the level of the active silicon that will become the transistor. It is critical to keep the dishing low and the step height over the active silicon consistent for the sake of proper device performance. 

This chapter is not intended to be a literature survey, since an excellent review paper on phase diagrams of silicon nitride-metal oxide systems has been written by Sorrell [5], This chapter, is, however, intended to illustrate the use of phase diagrams to study silicon nitride ceramics. 

In the mass titration method, the PZC is determined as the natnral pH of a concentrated dispersion. A detailed description of the experimental procedure can be found in [667], Mass titration become popular in the late 1980s [668,669], but the same method was already known in the 1960s as the pH drift method [183], Usually, a series of natural pH values of dispersions with increasing solid loads is reported, but only the natural pH of the most concentrated dispersion is actually used. The only role of the data points obtained at lower solid loads is to confirm that a plateau was reached in pH as a function of solid load that is, a further increase in the solid load is unlikely to bring about a change in pH. The mass titration method is based on the assumption that the solid does not contain acid, base, or other surface-active impurities. This is seldom the case, thus mass titration often produces erroneous PZCs. In this respect mass titration is similar to the potentiometric titration without correction illustrated in Figure 2.7, only the solid-to-liquid ratio is different. The experimental conditions in mass titration (solid-to-liquid ratio, time of equilibration, nature and concentration of electrolyte, and initial pH) can vary, but little attention has been paid to the possible effects of experimental conditions on the apparent PZC. The effect of an acid or base associated with solid particles on the course of mass titration was studied in [670], To this end, a series of artificially contaminated samples was prepared by the addition of an acid or base to a commercial powder. The apparent PZC of silicon nitride obtained in [671] by mass titration varied from 4.2 (extrapolated to zero time of equilibration) to 8.2 for time of equilibration longer than 20 days. The method termed mass titration was used in [672], but it was different from the method discussed above. 

As already discussed, the formation of a nanocrystalline/amorphous (or an nc/nc) composite schematically illustrated in Fig. 4 and its thermal stability require a high immiscibility of the components. This is fulfilled, for example, in systems consisting of a stable transition metal nitride and silicon nitride. A simple estimate shows that in such a system, the immiscibility is assured if the activity of nitrogen is sufficiently high at the given temperature to shift the equilibrium of reaction (10) far to the left hand side [63,73,74]... 

When etching single crystal materials such as (100) and (110) silicon, the lateral etching beneath the protective silicon dioxide or silicon nitride is effectively stopped by slow-etching (111) planes that produce well-defined geometries such as V-grooves and deep vertical slots (Allen 1981) as illustrated in Fig. 3. 

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