Effects of O/sub 2/ rapid thermal annealing on the microstructural properties and reliability of RF-sputtered Ta/sub 2/O/sub 5/ films

Abstract

The microstructural properties and reliability of spnttered Taz05 films treated by various temperaturcs of rapid thermal annealing (ICIA) in O2 atmosphere have been systematically investigated. Analytical rcsnlts rcvcaled that whenever the ICrA temperature was >650T, the noncrystallinity of as-grown Ta205 film would be effectively improved from an amorphous phasc to the p-Ta20s phase. Leakage currcnt mcasurcmcnt indicated that leakage current decreases with increasing anilealing temperature in a low RTA temperatiire range (<6BOT) and, contrarily, increases with increasing anncaling temperature in a high IlTA temperature range (650 to 950°C). Thc fortncr result was asserted that reducing pinholes and oxygen vacancies played bey factors. However, thc latter result was snggcstcd to arise due to significant Si diffusion into the Ta20s film, cawing a leaky transition laycr andlor being distributed along tlic grain boimdary to form the leakage path. Finally, thc time-dependent dielectric-breakdown experiments revealed that 950°C O2 ~T A treated Ta20s film possessed the supcrior crystallinity, crcating less interfacial hole trap states at the junction of Ta20s1Si and exhibiting the best long-term reliability ffects of Rapid Thermal Annealing 011 Rr-sputtered Films IEEE Tixisactioris oii Dielectrics arid Electrical Insulation Vol. 7 N o . 3, rune 2000 323