Effects of additive elements on improvement of the dielectric properties of Ta2O5 films formed by metalorganic decomposition

Abstract

Ta 2 O 5 -based composite thin films formed by metalorganic decomposition have been investigated with respect to their dielectric properties. The dielectric and insulating properties of composite (1−x)Ta2O5−xTiO2 and (1−x)Ta2O5−xWO3 thin films are found to be improved compared to those of pure Ta2O5 thin films. In particular, thin films with x=0.08 composition of additive TiO2 or WO3 to Ta2O5 exhibited superior dielectric and insulating properties. The maximum dielectric constant and charge storage density of composite films are about 20 and 53.6 fC/μm2, respectively, higher than those of pure Ta2O5 films (about 13 and 34.5 fC/μm2). The temperature coefficient of the dielectric constant of composite films dramatically decreases from 65 ppm/°C for pure Ta2O5 to less than 11 ppm/°C. The leakage current density of composite films is lower than 1×10−9 A/cm2 up to an applied electric field of 3 MV/cm. The dominant conduction is Poole–Frenkel conduction in the films according to the measurement temperature dependence of the I−V characteristics.

Solution‐Processed HafSOx and ZircSOx Inorganic Thin‐Film Dielectrics and Nanolaminates

“…Likewise, derivative compositions may have chemical, mechanical, or processing characteristics that befit other applications. The SOx dielectric properties are comparable to those observed for other complex oxide films that have been produced via techniques such as atomic layer deposition (ALD), [30][31][32][33] physical vapor deposition (PVD), [34][35][36] or other methods [37][38][39][40][41] in support of conventional silicon-based electronics. In these systems, emphasis has been placed on development of multiple-component materials to inhibit crystallization and produce more robust breakdown characteristics relative to the simple binary oxides.…”

Physical modeling of electrical and dielectric properties of high-k ta2o5 based MOS capacitors on silicon

“…Doped, mixed and laminate high-permittivity (high-k) dielectric stacks attract progressively higher attention as a solution for further improvement of their electrical and dielectric properties [1]- [13]. It has been shown that Ta 2 O 5 , known as one of the most attractive dielectrics for the nanoscale dynamic random-access memories, can improve further by doping with convenient elements [14]. Detailed studies of the properties of tantalum pentoxide doped with Al, Ti and Hf and mixed with HfO 2 have been reported [15]- [30].…”

Ti-doped Ta<inf>2</inf>O<inf>5</inf> stacked capacitors

“…The positive value of Q f is related to oxygen vacancies which are donor-type charged defects in metal oxides and produce positive oxide charge in oxygen deficient films. According to recent models [8], [9] the oxygen vacancies in Ta 2 O 5 can be compensated by Ti 4+ ions as they are substitutionally incorporated into Ta 5+ sites in Ta 2 O 5 films. Considering this assumption (Ti 4+ radius, 0.068 nm, is almost the same as that of Ta 5+ ion, 0.07 nm), the observed reduction of the positive charge after Ti addition can be a result of this compensation.…”

“…The mixing of Ta 2 O 5 with another oxide is a promising way for improving the properties of pure Ta 2 O 5 and to suppress the negative effect of lower-k interface layer. The dielectric properties of films with addition of TiO 2 , Y 3 O 3 or WO 3 to Ta 2 O 5 were found to be improved compared to those of pure Ta 2 O 5 [6], [8]. The results of various authors, however, imply that the doping-induced variation in electrical characteristics of stack capacitors presumably depends not only on the amount of dopant but also on the method of doping leading to composite dielectric as well as on the fabrication method of Ta 2 O 5 itself.…”