Physical silicon nitrides

Non-oxide ceramics such as silicon carbide (SiC), silicon nitride (SijN ), and boron nitride (BN) offer a wide variety of unique physical properties such as high hardness and high structural stability under environmental extremes, as well as varied electronic and optical properties. These advantageous properties provide the driving force for intense research efforts directed toward developing new practical applications for these materials. These efforts occur despite the considerable expense often associated with their initial preparation and subsequent transformation into finished products. 

Lin, X.M., Jaeger, H.M., Sorensen, C.M. and Klabunde, K.J. (2001) Formation of long-range-ordered nanocrystal superlattices on silicon nitride substrates. Journal of Physical Chemistry B, 105 (17), 3353-3357. 

J. Sun, N. Lindvall, M.T. Cole, K.B.K. Teo, A. Yurgens, Large-area uniform graphene-like thin films grown by chemical vapor deposition directly on silicon nitride, Applied Physics Letters, 98 (2011) 252107. 

Osenbach, J. W. Sodium diffusion in plasma-deposited amorphous oxygen-doped silicon-nitride (alpha-SiON H) films. Journal of Apphed Physics 63, 4494—4500 (1988). 

The carbides and nitrides are well known for their hardness and strength, and this section will briefly compare a number of these properties with those of the pure metals. Concentration will be placed here on the first row compounds, since these constitute a complete series, and Mo and W, since these are the most commonly studied metals. As will be shown, the physical and mechanical properties of carbides and nitrides resemble those of ceramics not those of metals. Comparisons will be made with boron carbide (B4C), silicon carbide (SiC), aluminium nitride (AIN), silicon nitride (Si3N4), aluminium oxide (A1203), and diamond, as representative ceramic materials. 

NISTCERAM National Institute of Standards and Techology Gas Research Institute, Ceramics Division mechanical, physical, electrical, thermal, corrosive, and oxidation properties for alumina nitride, beryllia, boron nitride, silicon carbide, silicon nitride, and zirconia... 

Although CVD and plasma deposited films offer excellent properties as a passivation layer, the inability to reproduce chemical and physical properties has been a problem. Depending on gas flow rates and deposition conditions, free Si, H, C and 0 may be Incorporated into the films. Characterization of these films has been restricted almost exclusively to surface analytical techniques and ellipsometry. AES and XPS have been used to determine the C, N, 0, and Si content of CVD silicon nitride. 

Final Report 2004, EC/BBW Contract No. ICA-CT-2000-10020, FP5 INCO-Copemicus project LAMINATES (Silicon Nitride Based Laminar and Functionally Graded Ceramic Composites for Engineering Applications), project partners University of Warwick (UK), FCT Technologie (Germany), Institute for Problems of Materials Science (Ukraine), Materials Research Center Ltd (Ukraine), Institute for Problems of Strength (Ukraine), Institute of Chemical Physics (Armenia), Drexel University (USA), EMPA (Switzerland). 

A homemade SMFS with a silicon nitride cantilever (Park, Sunnyvale, CA) was used. Each tip was calibrated by using a standard sample. The spring constants of these cantilevers were in the range 0.010-0.012 N/m. By moving the piezo tube, one could bring the sample into contact with the AFM tip so that some polymer chains were physically adsorbed onto the tip, resulting in a number of bridges . As the distance between the tip and the substrate increased, the chains were stretched and the elastic force deflected... 

For silicon nitride films made in a cold-wall, pa rail el-pi ate reactor operating at 50 kHz, 200 mTorr, gas flows of SiH4/NH3/N2 = 140/270/800 seem and 500 watts of power, we can compare chemical and physical properties with thermally-deposited silicon nitride. Such a comparison is shown in Table 1.2... 

Within the past decade, research on the development of new Si3N4 compositions has greatly intensified. These efforts have resulted in a proliferation of new synthetic procedures. Preparative routes have been developed with increasing emphasis on the control of purity and physical properties. Silicon nitride powders, fibers, coatings, and composites each have their own characteristic requirements, which can dictate the choice of a particular route (i). 

Whenever silicon nitride is synthesized in the presence of aluminum-containing compounds (frequently used as a flux material in process of growing whiskers), there is a high probability of the formation of /3 -SiA10Ns. Up to two-thirds of the silicon in /3-Si3N4 can be substituted by Al without a change of structure. The /3 -SiAl()N has mechanical and physical properties similar to y3-Si3N4. It is, however, thermodynamically more stable than silicon nitride. 

In a non-hermetic package, the primary moisture barrier is typically a thin, (<0.1 micron) inorganic passivation layer of silicon dioxide or silicon nitride. However, passivation layers cannot withstand physical handling and they are not resistant to saline exposure. Additional protection is needed in the form of organic polymer coatings. 

PHYSICAL AND CHEMICAL PROPERTIES OF SILICON NITRIDE FILMS FROM SiH4 + NH3 + N2 [195]... 

Figure 14.27a Courtesy of Hans-Joachim Kleebe. Figure 14.27b Reprinted with permission from Shibata, N., Painter, G.S., Satet, R.L., Hoffmaim, M.J., Pennycook, S.J., and Becher, P.F. (2005) Rare-earth adsorption at intergranular interfaces in silicon nitride ceramics Subnanometer observations and theory, Phys. Rev. B 72, 149191R. Copyright 2005 by the American Physical Society.

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