Porous SiOCH Thin Films Obtained by Foaming

Abstract

Porous organosilicate thin films (SiOCH) deposited by plasma-enhanced chemical vapor deposition (PECVD) are used as dielectric layers in advanced microelectronic interconnections and as chemical layers in chemical sensors and biosensors. One challenge is to increase the porosity in these films, the classical method being limited to porosity rate close to 50%. In this paper, we report an innovative and simple strategy to perform highly nanoporous SiOCH thin films without the use of any templates or external blowing agents. This approach uses a SiOCH deposited by PECVD (without any porogens) intentionally covered by a dense crust. The porosity generation is obtained through an ultraviolet (UV)-assisted thermal annealing of the stack. The highest porosities ever demonstrated for SiOCH PECVD thin films are obtained (porosity close to 65%). The impact of different process parameters (choice of precursor, deposition, and annealing conditions) on the creation of porosity is studied. The porosity introduction with this original method can be related to a foaming mechanism: a gas is produced inside the film during the UV-assisted curing which causes a film expansion and allow the creation of porosity.

Influence of double bonds and cyclic structure on the AP‐PECVD of low‐korganosilicon insulating layers

“…For each deposition condition (monomer and frequency), the thickness and mass growth rates were determined from the measured thicknesses and weight of a minimum of two different thin films prepared using different deposition times. The effective deposition time, which is the time effectively spent under the high-voltage electrodes and calculated independently from the plasma pulse frequency, corresponds to the number of runs (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) multiplied by the width of the high-voltage electrodes (30 mm) divided by the speed of the moving table (1-3 mm•s −1 ). For all the experiments reported in this study, the growth rates were shown to be directly proportional to the deposition time, yielding small standard deviations of the growth rates, even though they were evaluated from thin films prepared with different deposition times.…”

“…[ 5 ] Plasma‐enhanced chemical vapour deposition (PECVD) processes have been widely used for the elaboration of low‐ k thin films. [ 6,7 ] If several strategies (i.e., porogen approach, [ 8 ] foaming approach, [ 9 ] cyclic precursor approach [ 10 ] and carbon‐bridging approach [ 11 ] ) have been proposed to lower the dielectric constant of the materials, the resulting thin films, called “plasma polymers,” suffer from moderate‐to‐poor retention of the precursor structure or/and limited mechanical or insulating properties. In particular, the PECVD of low‐ k dielectric thin films from constitutive porosities (e.g., cyclic precursor approach) is restricted by the disruption of the ring structure of cyclic precursors.…”

Blowing Properties and Functionality of Thermoplastic Polyester Film Using Thermally Expandable Microcapsules

“…Therefore, TPEEs are applied to components and lightweight seats for automobiles, outdoor products where elasticity is important according to the fashion trend of seeking comfort for clothing, and for interior building materials [8]. In addition, TPEEs have been receiving interest by industries as ecofriendly materials because they can save energy and reduce raw material and production costs due to their light weight [9].…”

Fabrication of Silicone Rubber Foam with Tailored Porous Structures by Supercritical CO2

“…However, there are many drawbacks in chemical forming. On one hand, the cell size of foam obtained with chemical foaming is usually dozens of micrometers . Liu prepared foams with 31–34 μm cell size from irradiation cross‐linked silicone rubber by using azodicarbonamide (AC) foaming agent .…”

“…On one hand, the cell size of foam obtained with chemical foaming is usually dozens of micrometers. [5][6][7][8][9] Liu prepared foams with (2 of 11) 1600377 finalization. Size finalization can be achieved by cooling (thermoplastic material) or vulcanization (rubber).…”