Preparation of amorphous fluoride films by electron cyclotron resonance plasma-enhanced chemical vapor deposition

Amorphous ZnF2, ZnF2-BaF2, AlF3 and AlF3-BaF2 films were prepared on CaF2(1 11) substrates by an electron cyclotron resonance plasma-enhanced chemical vapor deposition (CVD) technique. Metal beta -diketone chelates and NF3 gas were used as starting materials and a fluorinating gas, respectively. ZnF2 films deposited on the substrates kept at 300 degreesC and 100 degreesC we re crystalline and amorphous, respectively. The crystalline ZnF2 thin film prepared at a deposition rate of 0.2 mum h(-1) was oriented along a [110] d irection. The amorphous ZnF2 film, tinted yellowish brown, had an IR spectr a which were due to contaminants. Colorless and contaminant-free amorphous films were obtained for a 60ZnF(2). 40BaF(2) composition. On the other hand , AlF3; films generated on the CaF2(I 1 1) substrate kept at 300 degreesC w ere amorphous and colorless. We also found that amorphous 80AlF(3). 20BaF(2 ) and 60AlF(3). 40BaF(2) films could be synthesized at a deposition rate of 1.5 mum h(-1). (C) 2001 Elsevier Science B.V. All rights reserved.