Properties of Amorphous and Crystalline Ta 2 O 5 Thin Films Prepared by Metalorganic Solution Deposition Technique for I
- PDF / 1,056,415 Bytes
- 6 Pages / 391.5 x 607.5 pts Page_size
- 54 Downloads / 199 Views
ABSTRACT We report on the properties of Ta 20 5 thin films prepared by the metalorganic solution deposition (MOSD) technique on Pt-coated Si, ne-Si, and poly-Si substrates. The effects of postdeposition annealing temperature on the structural, electrical, and optical properties were analyzed. The electrical measurements were conducted on MIM and MIS capacitors. The dielectric constant of amorphous Ta 20 5 thin films was in the range 29.2-29.5 up to 600 'C, while crystalline thin films, annealed in the temperature range 650-750 'C, exhibited enhanced dielectric constant in the range 45.6-51.7. The dielectric loss factor did not show any appreciable dependence on the annealing temperature and was in the range 0.006-0.009. The films exhibited high resistivities of the order of 1012_1015 Q-cm at an applied electric field of 1 MV/cm in the annealing temperature range of 500-750 TC. The temperature coefficient of capacitance was in the range 52-114 ppmI°C for films annealed in the temperature range 500-750 TC. The bias stability of capacitance, measured at an applied electric field of 1 MV/cm, was better than 1.41 % for Ta 20 5 films annealed up to 750 TC. INTRODUCTION Ta 20 5 thin films have potential for numerous microelectronic applications such as gate dielectric of metal-insulator-semiconductor devices, optical waveguides, electroluminescent display devices, and surface acoustic wave (SAW) devices [1-5]. Tantalum oxide thin films are
attractive for scaled down capacitor in ultra large scale integrated (ULSI) circuits because of their high dielectric constant, low dielectric loss, low leakage current, low defect density, and good temperature and bias stability. The high dielectric constant and low dielectric loss materials are also attractive for microwave applications [4]. For successful integration into microelectronic devices, extremely reliable Ta20 5 thin films are desired. The properties of Ta 20 5 thin films have been reported to be strongly dependent on the fabrication method, nature of substrate and electrode material, and post-deposition annealing treatment. The technical literature shows a wide variation in the reported structural, dielectric, and insulating properties of amorphous and crystalline Ta20 5 thin films. An understanding of process-structure-property correlation is important to understand and compare various thin film studies reported in the literature and exploit Ta 20 5 thin films for devices. In this paper, we report on the systematic study of structural, optical, dielectric, and insulating properties of amorphous and crystalline Ta 20 5 thin films fabricated by MOSD technique. Detailed studies were conducted on MIM and MIS capacitors to analyze the influence of film/substrate interface on the electrical properties. EXPERIMENT Ta 20 5 thin films were fabricated by metalorganic solution deposition technique using tantalum ethoxide as precursor. 2-methoxyethanol was used as solvent. In the experiment, tantalum ethoxide was initially dissolved in 2-methoxyethanol. Finally, acetic acid was adde
Data Loading...
