Ultralow Dielectric Constant Tetravinyltetramethylcyclotetrasiloxane Films Deposited by Initiated Chemical Vapor Deposition (iCVD)

Abstract

Simultaneous improvement of mechanical properties and lowering of the dielectric constant occur when films grown from the cyclic monomer tetravinyltetramethylcyclotetrasiloxane (V4D4) via initiated chemical vapor deposition (iCVD) are thermally cured in air. Clear signatures from silsesquioxane cage structures in the annealed films appear in the Fourier transform IR (1140 cm−1) and Raman (1117 cm−1) spectra. The iCVD method consumes an order of magnitude lower power density than the traditional plasma‐enhanced CVD, thus preserving the precursor's delicate ring structure and organic substituents in the as‐deposited films. The high degree of structural retention in the as‐deposited film allows for the beneficial formation of intrinsically porous silsesquioxane cages upon annealing in air. Complete oxidation of the silicon creates ‘Q’ groups, which impart greater hardness and modulus to the films by increasing the average connectivity number of the film matrix beyond the percolation of rigidity. The removal of labile hydrocarbon moieties allows for the oxidation of the as‐deposited film while simultaneously inducing porosity. This combination of events avoids the typical trade‐off between improved mechanical properties and higher dielectric constants. Films annealed at 410 °C have a dielectric constant of 2.15, and a hardness and modulus of 0.78 and 5.4 GPa, respectively. The solvent‐less and low‐energy nature of iCVD make it attractive from an environmental safety and health perspective.

Template free preparation of nanoporous organically modified silica thin films on flexible substrates

“…[3][4][5][6][7][8] Furthermore, nanoporosity is added to ormosils in order to provide extra-functionalities such as high surface area [9][10][11] and therefore adsorption capacity, 12,13 and very low refractive index 14,15 and dielectric constant. 16 Nanoporous ormosil bulk materials and thin films can be prepared using selfassembling template molecules to form periodic nanopores 17 or by sacrificial polymers to induce nano-phase separation. 18 However, the additional removal step of sacrificial substances requires harsh conditions, i.e.…”

Failure mechanism analysis and process improvement on time-dependent dielectric breakdown of Cu/ultra-low-k dielectric based on complementary Raman and FTIR spectroscopy study

“…It is well known that the complementary application of Raman and Fourier transform infrared (FTIR) vibrational spectroscopy is one of the most common characterization tools and methodology for low-k and ultra-low-k material analyses and characterization. [10][11][12][13][14][15][16][17][18][19][20] In present work, we will describe the experiments and the setup to capture the dielectric bonding damage during the reliability test and an physical model based the experimental results was proposed on the Ta ions migration model and the line-edge-roughness (LER) model. Details on the two models are discussed in later sections.…”

Initiated-chemical vapor deposition of organosilicon layers: Monomer adsorption, bulk growth, and process window definition

“…In the past years, initiated-chemical vapor deposition (i-CVD) has proven to be a very well suited approach toward vacuum deposition of polymeric films for application in many fields where specific surface and bulk properties are desired, i.e., hydrophobicity/hydrophilicity, 1,2 antimicrobial, 3 binding of biological ligands, 4 biopassive dielectrics, 5 low-k materials 6 and, recently, as responsive materials 7 and organic interlayers in multilayer moisture and oxygen barrier systems. 8,9 The advantage of the i-CVD approach with respect to the widely known hot wire CVD is the lower thermal budget required for the polymerization process to occur.…”

“…In literature a similar observation has been reported for the polymerization of the tetravinyl-tetramethyl-cyclotetrasiloxane, showing a shift of the cyclotetrasiloxane band from 1075 cm À1 (monomer) to 1065 cm À1 (polymer). 6 The ring opening can be excluded since this would imply a broadening of the absorption band and the appearance of a shoulder at 1080 cm À1 , 5,17 related to linear Si-O-Si chains, which is not present in the polymer spectrum in Fig. 2.…”