Mechanical characterization of porous nano-thin films by use of atomic force acoustic microscopy

Abstract

The indentation modulus of thin films of porous organosilicate glass with a nominal porosity content of 30% and thicknesses of 350nm, 200nm, and 46nm is determined with help of atomic force acoustic microscopy (AFAM). This scanning probe microscopy based technique provides the highest possible depth resolution. The values of the indentation modulus obtained for the 350nm and 200nm thin films were respectively 6.3GPa±0.2GPa and 7.2GPa±0.2GPa and free of the substrate influence. The sample with the thickness of 46nm was tested in four independent measurement sets. Cantilevers with two different tip radii of about 150nm and less than 50nm were applied in different force ranges to obtain a result for the indentation modulus that was free of the substrate influence. A detailed data analysis yielded value of 8.3GPa±0.4GPa for the thinnest film. The values of the indentation modulus obtained for the thin films of porous organosilicate glasses increased with the decreasing film thickness. The stiffening observed for the porous films could be explained by evolution of the pore topology as a function of the film thickness. To ensure that our results were free of the substrate influence, we analyzed the ratio of the sample deformation as well as the tip radius to the film thickness. The results obtained for the substrate parameter were compared for all the measurement series and showed, which ones could be declared as free of the substrate influence.

Design of Ultrastiff Organosilicate Hybrid Glasses

“…It has been reported in several studies that the addition of nanoporosity severely degrades the elastic and fracture properties of these materials, and further complicates their resistance to processing conditions. [22][23][24][25][26][27] Nevertheless, our new design approach promises to achieve mechanically more robust hybrid networks with even a lower density and dielectric constant by incorporating nanometer size porosity into the ultrastiff glass network.…”

Mechanically Defined Microgels by Droplet Microfluidics

“…Theoretically, the beam of the cantilever can be described as a Hookean spring, and its deflection is typically monitored with the optical lever technique. Such cantilevers are commercially available with selectable spring constants allowing for measuring elastic moduli between some hundreds of Pa up to several GPa . The actual probe interacting with the sample is classically a sharp tip with tip radii in range of 10 to 150 nm.…”

Analytical Study of Porous Organosilicate Glass Films Prepared from Mixtures of 1,3,5- and 1,3-Alkoxysilylbenzenes

“…However, the ≡Si-CH 3 terminal groups also affect the mechanical properties by reducing the silicon network connectivity number in the low-k skeleton [8]. An additional problem with mechanical properties is related to the porosity of the films that reduces the stiffness of low-k materials [9][10][11][12]. Therefore, it is very important to ensure the preservation of good mechanical properties while decreasing the dielectric constant k by increasing the porosity [13,14].…”