Thickness Control of Coatings by Means of Modulated IR Radiometry

Abstract

Coatings prepared by reactive magnetron sputtering of approximately equal thermal transport properties but differing coating thicknesses are analyzed by means of non‐contact non‐destructive modulated IR radiometry. For the quantitative interpretation, the measured thermal wave signals are calibrated, using the signals measured for a homogenous opaque solid of smooth surface. The relative minima of the inverse calibrated phase lag signals are interpreted with respect to the effective thermal transport properties and to the coating thickness using an inverse solution of the two‐layer thermal wave problem. Based on measurements of various coatings, the limitations of this thermal wave method and the errors of measurement for the coating thickness are discussed by comparing with microscopic measurements.

Evolution of the functional properties of titanium–silver thin films for biomedical applications: Influence of in-vacuum annealing

“…The thermal characteristics of the coatings were accessed by modulated IR radiometry (MIRR) [35][36][37]. Small thermal oscillations were created in the samples by an intensity modulated laser beam acting as an excitation source.…”

“…MIRR is a non-contact and non-destructive photothermal technique which consists in heating a sample with a modulated light power (typically a laser) and then observing the emitted IR radiation. The knowledge of the amplitude and the phase shift at different modulated frequencies allows the determination of the thermal properties of layered systems like thin films and coatings [35][36][37][38]53]. In order to calculate the thermal parameters of the films, the extremum method was applied based on the solution of two-layer (film/substrate) thermal wave problem [35,38].…”

TiAgx thin films for lower limb prosthesis pressure sensors: Effect of composition and structural changes on the electrical and thermal response of the films

“…Extensive details on the experimental conditions and setup can be found in references [23][24][25]. Figure 1 shows the evolution of both target potential and deposition rate as a function of the area of the Ag pellets, placed on the target erosion zone.…”

Modulated IR radiometry as a tool for the thickness control of coatings

“…The results presented here are from a set of titanium oxycarbide (TiCO) thin films, prepared by reactive DC magnetron sputtering on high speed steel (AISI M2) substrates, using a laboratory-size deposition system. Deposition conditions were kept constant [7], with the deposition time the only independent variable parameter. The films were prepared with the substrate holder (in grounded condition) positioned at 70 mm from the target.…”

“…The argon flow was kept constant at 60 sccm in all depositions. The thickness of the coatings varied from about 2 to 6 µm, whereas their composition, structure (all films were crystalline, developing a face centred cubic-type lattice), and thermal transport properties were approximately constant [7]. The quantitative interpretation of the measured relative minima (Fig.…”