Perovskite thin films grown by direct liquid injection MOCVD

摘要

The Continuous scaling down of devices dimensions, in silicon technology, imposes to replace silicon dioxide. Among the potential candidates for new capacitors, some perovskite structure materials (such as titanate or zirconate) show interesting characteristics. The first way to develop perovskite films is to use a mixture of two p-diketonates by varying the solution's cationic ratio. However, our previous results on SrZrO_3 showed that a wide parametric study had to be carried on. Another way is to design novel heterometallic precursors that contain both cations on the same molecule. The ligands could be chosen so that peculiar evaporation and decomposition temperatures could be obtained. Thus, perovskite films (SrZrO_3) were deposited on plane Si(1 0 0) substrates by direct liquid injection MOCVD from two original heterometallic precursors Sr_2Zr_2(O~nPr)_8(thd)_4(~nPrOH)_2 and Sr_2Zr_2(thd)_4(O'Pr)_8. The oxide films were deposited at substrate temperature ranging from 550 to 900 ℃. At the lowest temperatures (550 and 600 ℃) the as-deposited films were amorphous. After a postannealing at 700 ℃ for 1 h under N_2/O_2, the films deposited at 550 ℃ were crystallized in the SrZrO_3 orthorhombic phase. Crystallographic and chemical structures were controlled applying grazing X-ray diffraction and infrared spectroscopy measurements. Results are discussed with respect to experimental synthesis conditions.