Dielectric thin films

Shutt J D, Batzel D A, Sudiwala R V, Rickert S E and Kenney M E 1988 Fabrication of thin-film dielectrics from an amphiphilic 2-ring phthalocyanine Langmuir4 1240-7... 

There is also growing iaterest ia thin-film dielectric capacitors. For example, through the use of processiag techniques such as sol—gel solution deposition, thin (--- 0.25 fim) ceramic layers having dielectric constants ranging from 500 to 2000 ia the PZT, Pb(Zr,Ti)03, and PMN—PT, Pb(Mn2 3Nb2 3)03-PbTi03, compositional families respectively, have been prepared (3). 

Figure 4.6. Cross-sectional SEM images of an A1PO film deposited on Si02 and cured at (a) 275 °C, and (b) flash annealed to 600 °C. [Reproduced with permission. Meyers, S. T. Anderson, J. T. Hong, D. Hung, C. M. Wager, J. F. Keszler, D. A. 2007. Solution processed aluminum oxide phosphate thin-film dielectrics. Chem. Mater. 19 4023-4029. Copyright 2007 American Chemical Society.]...

Thin-film dielectrics (Ba0 92Ca108)(Ti0 92Zr0 08)O3 for the thin-film capacitors were prepared using Ba, Ca, and Zr ethoxides and Ti isopropoxide in refluxed methoxyethanol solutions as precursors. Films were deposited on a usual platinized Si substrate. Crystalline thin films after heat treatment at 800°C demonstrated dielectric permittivity of 1200, dielectric loss of0.5%, nonlinear coefficient a = 0.92, and break-down voltage of980 V [1595],... 

A recent report presented Continuous Composition Spread (CCS) approaches (37) to identify thin film dielectrics with varying composition among the system Zr-Sn-Ti-O (78). A structural-driven approach was applied to the discovery of a high dielectric perovskite polymorphic material (79). 

The results presented here demonstrate that thin films can be characterized based on acoustical monitoring of changes in film mass density, conductivity, and viscoelasticity. Additional sensing mechanisms are available to probe film properties. Some examples are thin-film dielectric constant, stress, and structure (e.g., roughness). Some of these sensing mechanisms will be hard to quantify since they involve a complex interaction (e.g., wave attenuation based on wave scattering due to film roughness) however, they may still be useful to provide a qualitative monitor based on empirical data. 

Van Dover, R. B. Schneemeyer, R. F. Fleming, R. M., Discovery of a useful thin-film dielectric using a composition-spread approach, Nature 1998, 392, 162... 

Thin film dielectrics are usually deposited using chemical vapor deposition (CVD). A variation of CVD utilizing a plasma discharge is called plasma-enhanced CVD (PECVD) and is the standard in IC fabrication for the deposition of dielectric films. Plasma-enhanced CVD involves the formation of a solid film in a substrate surface from volatile precursors (vapor or gas) in a plasma discharge. The precursors are chosen to contain the constituent elements of the final film and chemical reactions in the gas phase are encouraged. They are condensed in a substrate that is heated or cooled. It will be shown later that porosity can be introduced in the PECVD films. Spin coating is another preparation technique and a popular choice... 

There are important points to note about these variables. First, a small impurity composition can cause a big change in the figure of merit, as seen by the rapid variation of catalytic activity in the Cu/Rh oxidation catalyst (Cong et al., 1999). Second, the phases in thin film are not necessarily the same as those in bulk, as seen in the case of the thin-film dielectric, where the optimal material was found outside the region where the bulk phase forms (van Dover et al., 1998). Finally, the crystallinity of the material... 

PBO and PBZT films can be made very thin (less than 0.002 in.) and can be impregnated with secondary resins, resulting in a substrate with a dielectric constant less than 2.8, an isotropic planar CTE of 7 ppm per °C or less, and temperature resistance over 250°C. Copper circuits and ground planes can be added by a variety of additive or substrative means, and multilayer circuit boards can be fabricated using plated through holes. Further development of these thin film dielectric substrates should result in interconnection density over 100 times greater than is currently possible with fiber reinforced epoxy multilayer boards. 

Figure 5-18. Dependence of 1102 thin film dielectric constant (Cr) on water vapor concentration. Films grown at 400°C usingTi(0(-Pr)4 as the precursor source (Data from [128]).

---