Liquid injection ALD and MOCVD of lanthanum aluminate using a bimetallic alkoxide precursor

Abstract

Lanthanum aluminate has been deposited for the first time by liquid injection atomic layer deposition (ALD) using a bimetallic alkoxide precursor, [LaAl(OⁱPr)₆(ⁱPrOH)]₂ with H₂O as oxygen source. The ALD growth rate was constant in the temperature range 160–300 °C, but ALD growth was not fully self-limiting. Comparisons are made with film growth by liquid injection MOCVD. Auger electron spectroscopy (AES) showed that the films contained no detectable C contamination (detection limit ∼0.5%) and XRD showed that films remained amorphous at temperatures below 850 °C. Films grown by ALD were all La deficient with La : Al ratios of 0.50–0.61; films grown by MOCVD at 300 and 450 °C have La : Al ratios of 1.24 and 0.84, respectively. C–V and leakage current data for films grown by ALD and MOCVD are presented and a LaAlO_x film (La : Al = 0.54) film had a permittivity (k) of ∼13.