Influence of a 5 Å Tantalum Nitride Interface Layer on Dielectric Properties of Zirconium-Doped Tantalum Oxide High-k Films

Abstract

A 5 Å thick tantalum nitride ͑TaN x ͒ interface layer was inserted between an 8 nm Zr-doped tantalum oxide ͑TaO x ͒ high-k film and a silicon substrate to improve dielectric properties for metal-oxide-semiconductor ͑MOS͒ gate dielectric applications. Compared to the Zr-doped TaO x film without the TaN x interface, the stacked structure showed improvement in the dielectric constant, leakage current density, and dielectric breakdown strength. However, the flatband voltage shift and interface state densities were slightly degraded. Hysteresis of C-V curves did not change substantially with this TaN x insertion. Structural and chemical analyses, i.e., secondary ion mass spectroscopy ͑SIMS͒ and X-ray photoelectron spectroscopy ͑XPS͒, were done to investigate this TaN x interface layer. The results suggested that TaN x reacted with oxygen atoms from the high-k film and formed tantalum oxynitride ͑TaO x N y ͒ after being annealed at 700°C in O 2 , which may be responsible for the observed improvement on dielectric properties.

Impact of Si substrate nitridation on electrical characteristics of Ta2O5stack capacitors

“…The slope of the curves of samples treated at 700 • C is slightly higher than the one corresponding to T n = 800 • C indicating a lower density of the interface states in the former case not only near the midgap but also in the whole Si bandgap. These results are in agreement with those reported by Tewg et al [26] who show that the TaO x N y interfacial layer slightly degrades the V fb shift and interface state density, but improves the dielectric constant and the leakage current. As seen in the next section leakage current improvement is also observed in our samples.…”

“…The techniques mostly employed to perform the nitridiation of Si wafers are rapid thermal and plasma processing in ammonia, nitrous oxide and nitric oxide and chemical vapour deposition [15][16][17][18][19][20][21][22][23][24][25]. Introduction of a thin (0.5 nm) TaN x layer which is transformed to TaO x N y after Ta 2 O 5 deposition and high temperature annealing was also suggested in order to improve the dielectric and electrical properties of the stacks [26]. Recently, we have reported that thin Ta 2 O 5 films with excellent electrical characteristics can be successfully obtained by thermal oxidation of preliminary deposited Ta layers on Si [4,[27][28][29][30].…”

Conductivity Switching of N-Doped Ta Oxide Nanotubular Arrays

“…Another important observation is the positive slope of the MS plots, indicating that the TaO x N y NTs are n-type semiconductors, consistent with the literature . In order to calculate the donor density ( N D ) from the gradient of the MS plot, the permittivity of TaN y (∼26) was used . This analysis gives an N D value of 1.7 × 10 21 cm –3 at 100 kHz and 5.7 × 10 21 cm –3 at 25 kHz, which is quite similar to previously reported values for N-doped TiO 2 NTs (3.9 × 10 20 cm –3 ).…”

“…12 In order to calculate the donor density (N D ) from the gradient of the MS plot, the permittivity of TaN y (∼26) was used. 53 This analysis gives an N D value of 1.7 × 10 21 cm −3 at 100 kHz and 5.7 × 10 21 cm −3 at 25 kHz, which is quite similar to previously reported values for N-doped TiO 2 NTs (3.9 × 10 20 cm −3 ).…”

Electrical Improvement of Fluorine-Passivated Metal–Organic Chemical Vapor Deposited TiO2 Film on (NH4)2Sx-treated GaAs

“…The high leakage current is due to the film defects 11,19) and high value of D it . 20,21) The C-V characteristics of MOCVD-TiO 2 / GaAs show a stretch-out phenomenon as shown in Fig. 2(a).…”