Factors influencing the nanostructure of obliquely deposited thin films

Abstract

In this piece of work, silica thin films were deposited by RF magnetron reactive sputtering exploiting the mechanism of oblique angle deposition. Here, change in the structure of the films with a change in the oblique angle of deposition and target to substrate distance has been studied with some emphasis on the role of the atomic weight of silicon in influencing the collisional process and directionality of the sputtered atoms. The films deposited at a lower target to substrate distance are compact and possess a columnar structure when deposited at higher oblique angles. The films deposited at higher target to substrate distance do not show any change in the tilt angle of the nanocolumnar structure with change in the oblique angle of deposition. This shows that the mean free path of the sputtered atoms plays a major role in the evolution of the structures of the thin films.

Coatings for Core–Shell Composite Micro‐Lattice Structures: Varying Sputtering Parameters

“…The directionally oriented growth along the sidewall of the 90° and ±30° samples is indicative of atomic shadowing due to the region being orthogonally oriented to the planar cathode surface. [ 55,60 ] It was also noted that samples coated in the 90° planar configuration showed a distinct divot in the sidewall coating, further indicating that the sidewall regions experience low exposure to the deposition flux under planar cathode configurations, which ultimately can result in large uniformity gradients. A more homogeneous morphology was achieved in the ICM coated samples as a result of the increased angles of exposure to the sidewalls offered by the cathode geometry.…”

“…Variations in Ar pressure and sputtering power, as well as cathode geometry, greatly influence the plasma density within the sputtering system, and in turn the degree of collisions during deposition and directionality of the depositing atoms. [45,[55][56][57] Fundamentally, the tubular nature of the ICM cathode promotes more collisions amongst trapped electrons with neutrals and ionized species and inherently produces higher plasma densities compared to planar configurations. [57,58] The subsequent increase in Ar pressure (from 3 to 6 mTorr) and sputtering power (from 100 to 200 W) within the ICM may have resulted in additional degrees of scattering of the depositing flux due to a corresponding increase in ion and electron density, [45,59] ultimately decreasing the proportion of incident sputtered metal atoms penetrating the lattice structure.…”

Analysis of ZnS and MgF2 layered nanostructures grown by glancing angle deposition for optical design

“…Before explaining the properties of column growth at extreme angles, an analytical derivation of the empirical formula called the tangent rule is required to explain the growth mechanisms. Other studies of the empirical formula called tangent rule and the generalized tangent rule found in our literature search reported that the formula was empirically established but did not analyze the possible physical restrictions of the equations [36][37][38].…”

Broadband Anti-Reflection Coatings Fabricated by Precise Time-Controlled and Oblique-Angle Deposition Methods

“…SiO 2 coatings are known for their long-term stability and high transmittance in a wide spectral range. By convention, the refractive index of dense SiO 2 is about 1.46, while the refractive index of porous SiO 2 can be reduced to 1.1 or lower by increasing the porosity [25][26][27].…”