TiO₂ thin film patterns prepared by chemical vapor deposition and atomic layer deposition using an atmospheric pressure microplasma printer

Abstract

A microplasma printer is employed to deposit thin film patterns of TiO2 by titanium tetra‐isopropoxide and N2/O2 plasma at atmospheric pressure. The setup is adopted to carry out deposition in two configurations, namely under chemical vapor deposition (CVD) and atomic layer deposition (ALD) modes. The properties of TiO2, as well as the patterning resolution, are investigated. The amorphous TiO2 deposited in the CVD mode contains a relatively high level of impurities (residual carbon content of 5–10 at.%) and is characterized by a low refractive index of 1.8. With the ALD mode on the other hand, TiO2 is obtained with a low level of impurities (<1 at.% C and <2 at.% N), a refractive index of 1.98, and a growth per cycle of 0.15 nm. Furthermore, the spatial resolution for a 8‐nm‐thick film is determined by X‐ray photoelectron spectroscopy line scan and found to be equal to 2,000 and 900 µm for the CVD and ALD modes, respectively. This study can be regarded as the first step toward area‐selective CVD and ALD of TiO2 by a microplasma printer, which can be further explored and extended to other material systems.

Plasmas for additive manufacturing

“…A microplasma printer which was originally developed for surface functionalization has also now been demonstrated for patterned deposition of metal oxide films via atomic layer deposition (ALD). [ 140 ] Importantly, the printing head illustrated in the left of Figure 12a is comprised of multiple needle electrodes (top right of Figure 12a) that can individually actuate (bottom right of Figure 12a) to selectively deposit and obtain patterned films. Though these results remain primarily focused on 2D geometries, one can easily envision the build‐up of layers in 3D.…”

“…Plasmas in three‐dimensional (3D) printing configurations. (a) Microplasma printer composed of a multi‐needle‐to‐plate dielectric barrier discharge shown by illustrations of printing head (left), printing when all needle electrodes are activated (top right), and printing a pattern when specific needle electrodes are activated (bottom right), reprinted with permission from Aghaee et al [ 140 ] (b) Capacitively‐coupled radiofrequency plasma with a double‐helix electrode configuration termed HelixJet shown by photo at 3‐ns exposure time (left), 3D plot of the calculated electric field (middle), and axial cut ( y = 0) of the calculated electric field (right), reprinted with permission from Schafer et al [ 141 ] Isosurfaces with constant electric field are indicated by A (102 kV/m), B (130 kV/m), and C1 or C2 (174 kV/m)…”

“…Therefore, the possibility of rapid treatment is realistic. Arrays of microplasma jets, as demonstrated by the microplasma printer, [ 140 ] could aid in shortening the processing times for larger area films.…”

Atmospheric Pressure Plasma Deposition of TiO2: A Review

“…Because it is still challenging to use PEALD to manufacture TiO 2 thin films roll-to-roll, other possibilities to use this technique for industrial applications were explored. Very recently, a micro-plasma printer was employed to deposit TiO 2 thin film with desired patterns using PEALD at atmospheric pressure with a N 2 /O 2 gas mixture [93]. The properties of TiO 2 films deposited by this method showed a higher refractive index and lower level of impurities compared to the properties of films deposited using the CVD technique.…”

“…The properties of TiO 2 films deposited by this method showed a higher refractive index and lower level of impurities compared to the properties of films deposited using the CVD technique. Moreover, the patterning resolution was twice as high as those from the latter technique, but it still requires more improvements to be applied in plasma printing technology in area-selective deposition [93].…”