Ziyun Wang

Metalorganic Chemical Vapor Deposition of Thin Film ZrO2 and Pb(Zr,Ti)O3: Precursor Chemistry and Process Characteristics.

Metalorganic chemical vapor deposition (MOCVD) process characteristics of several zirconium source reagents were investigated. These source reagents included metal β-diketonates [e.g., Zr(thd)4 where thd=(2,2,6,6-tetramethyl-3,5-heptanedionate)] and metal alkoxide/β-diketonates [e.g., Zr(OiPr)2(thd)2 and Zr(OtBu)2(thd)2]. Thermal properties and transport behaviors of these precursors were examined by thermogravimetric analysis. Zirconium oxide films were deposited on silicon substrates at reduced pressure. Under the process conditions examined, the deposition behavior was mass-transport controlled, and Zr(OiPr)2(thd)2 and Zr(OtBu)2(thd)2 behaved similarly. The films exhibited low carbon content. Pb(Zr, Ti)O3 (PZT) films were deposited on iridium-coated silicon substrates under reduced pressure. Zirconium incorporation efficiency was significantly improved for Zr(OiPr)2(thd)2 when compared to Zr(thd)4. Use of M(OtBu)2(thd)2 (where M=Zr or Ti) as source reagents for MOCVD of PZT was examined and compared to M(OiPr)2(thd)2 analogues. In this case, higher process pressures were needed to improve the incorporation efficiencies of M(OtBu)2(thd)2 precursors.

Atomic layer deposition of CeO2 using a heteroleptic cyclopentadienyl-amidinate precursor

Cerium oxide thin films were deposited on fused silica using atomic layer deposition (ALD). The novel Ce precursor, Ce(iPrCp)2(N-iPr-amd) [bis-isopropylcyclopentadienyl-di-isopropylacetamidinate-cerium] is a room-temperature liquid with good thermal stability and evaporates cleanly. Water vapor was used as the oxygen source. The growth characteristics and film properties of ALD CeO2 were investigated. A relatively broad ALD window of 165–285 °C resulted in a constant growth rate of 1.9 A/cycle and good thickness uniformity. The films deposited at 240 °C were found to be polycrystalline with cubic structure without a preferential direction in as-deposited condition. However, films grown at 335 °C slightly favored a (200) preferred orientation. XPS analysis showed that films are free from contamination, and the Ce:O stoichiometry analysis revealed the existence of oxygen vacancies in the films with composition CeO1.74.Cerium oxide thin films were deposited on fused silica using atomic layer deposition (ALD). The novel Ce precursor, Ce(iPrCp)2(N-iPr-amd) [bis-isopropylcyclopentadienyl-di-isopropylacetamidinate-cerium] is a room-temperature liquid with good thermal stability and evaporates cleanly. Water vapor was used as the oxygen source. The growth characteristics and film properties of ALD CeO2 were investigated. A relatively broad ALD window of 165–285 °C resulted in a constant growth rate of 1.9 A/cycle and good thickness uniformity. The films deposited at 240 °C were found to be polycrystalline with cubic structure without a preferential direction in as-deposited condition. However, films grown at 335 °C slightly favored a (200) preferred orientation. XPS analysis showed that films are free from contamination, and the Ce:O stoichiometry analysis revealed the existence of oxygen vacancies in the films with composition CeO1.74.