Dielectric materials nanoporous

Typical nanopore materials are porous oxides or polymers that have an ultra-low dielectric constant (k < 2). Ultra-low k is significant in producing highspeed electronic devices such as the interconnect structure shown in Figure 13.8. Si02, which has a dielectric constant of about 4, is currently used as a dielectric material between interconnects in most microelectronic devices. When the packing density between multilevel interconnects increases, a low... 

To obtain low k, these three polarizations are kept as low as possible. An obvious way to have low polarizations is reduction of the density of the material N). The lower density will decrease the number of polarizable species in the films and thus results in a lower dielectric constant. This is done by incorporating low molecular weight molecules, space occupying molecules, inherently open structures, and, more significantly, introducing porosity. This entry presents an overview of nanoporous dielectric materials. This overview is not exhaustive because new materials are being developed as this entry is written. 

NANOPOROUS DIELECTRIC MATERIALS AND PORE GENERATION METHODS... 

Nanoporous Dielectric Materials Poly(propylene glycol)... 

In this review, nanoporous dielectric materials have been presented. The preparation techniques, methods of pore generation, and materials classification were discussed. Inorganic, organic, and hybrid films were also discussed. The nanoporous dielectric films were classified by preparation method, which includes block copolymer, solvent as porogen approach, surfactant templating, and sol-gel approach. This is still a very active field of research because no one film has satisfied all the stringent requirements in semiconductor device processing. 

Block polymers containing an etchable block have been used as precursors for nanoporous polymers [109]. Because nanoporous polymers have large internal surface areas, large pore volumes, and uniform pore dimensions, these materials were studied as separation/pmilication media, batteiy separators, templates for nanostructured materials, low dielectric materials, and low refractive index materials. Both pore wall functionality and robustness of the matrix are important for the practical use of nanoporous polymers. As shown in Eig. 5.16, PLA was selectively etched horn a blend with reactive block co-polymers to form a nanoporous material. 

Dielectric materials such as silicon nitride, silicon dioxide, polymers and glass are normally used for the fabrication of solid-state nanopore devices [25]. The pore conductance may be expected to be frequency-dependent, perhaps similar to the transmission line model by de Levie (for closed pores) [40] [41]. For simplicity (and since the DC case is much more common), this aspect is typically ignored. In simple terms, a nanopore device as shown in Fig. 14 A can then be represented by a combination of solution (or access) resistance R the frequency-independent pore resistance Rp re and a device capacitance Cp (or alternatively a constant-phase element (CPE)), cf. the... 

Various kinds of low- and ultra-low-fe nanoporous SiOCH dielectrics have been developed, and their nanostractures analyzed using quantitative gkS. " In general, a soluble, curable PMSSQ precursor was chosen as the didectric material. A variety of thermally labile organic polymer poro-gens were added to the didectric material to create dosed nanopores through thdr sacrifidal thermal degradation, delivering low-fe values to the dielectric material. 

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