Plasma deposition of metal oxide films for integrated optics

Plasma‐enhanced Chemical Vapor Deposition of Aluminum Oxide Using Ultrashort Precursor Injection Pulses

“…To study the relation between the pulse interval and the AlO x structural properties in more detail, infrared absorption measurements were carried out. Figure 4 shows the FTIR transmission spectra of AlO x films deposited using 100 precursor pulses, for Δ t values of 0.5, 1.5, and 3.5 s. Three regions of interest can be distinguished in the spectra: the absorption of the AlO stretching vibration between 400 and 1 000 cm −1 , OCO and CO stretching vibrations (in brief, CO) centered around 1 600 cm −1 and the broad signature of the OH stretching vibrations between 2 700 and 3 700 cm −1 33, 49, 50. In addition, the spectra reveal the presence of a thin interfacial silicon oxide layer (SiOSi stretching band, 1 020–1 090 cm −1 ) that is formed during AlO x deposition, in agreement with previous observations for PECVD and ALD 13, 20, 29.…”

“…In addition, it has recently been established that AlO x films can be used for the effective passivation of silicon surfaces 12–20. Depending on the application, AlO x is commonly synthesized by methods such as sputtering,17, 21 chemical vapor deposition (CVD),22, 23 plasma‐enhanced CVD (PECVD), 6, 7, 18–20, 24–33 and atomic layer deposition (ALD) 1–5, 13–16, 34–41. The latter two methods are especially suitable for the deposition of high‐quality AlO x films at low substrate temperatures ( T dep = ≈150–350 °C).…”

“…In the first half cycle the Al precursor is injected into the reactor and reacts with surface OH groups. Al(CH 3 ) 3 is by far the most popular Al‐precursor (for both ALD and PECVD processes),7, 18, 34–37 but also other precursors have been used including AlCl 3 25, 26, 33, 42. In the second ALD half cycle, the co‐reactant is introduced and reacts with the methyl‐terminated surface (when using Al(CH 3 ) 3 ).…”