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ABSTRACT: As a function of thermal treatment, the chemical stability of ultrathin ZrO2 films prepared by chemical vapor deposition on a silicon substrate is investigated by x-ray photoelectron spectroscopy. The chemical structure is stable up to 800 °C in both vacuum and N2 ambient, but a reaction forming zirconium silicide occurs above 900 °C in vacuum. The formation of silicide is accounted for by a reaction mechanism involving a reaction of ZrO2 with SiO, the latter formed above 900 °C at the interface between Si(100) and the thin layer of SiO2 formed during growth of the ZrO2. © 2001 American Institute of Physics.
Applied Physics Letters 01/2001; 78(3):368-370. · 3.84 Impact Factor
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ABSTRACT: The oxidation kinetics of ultra thin thermally NH3-nitrided Si3N4 films in N2O ambient has been extensively studied using angle resolved x-ray photoelectron spectroscopy (ARXPS). Ultra thin (7Å) Si3N4 films formed by RTP nitridation of Si in NH3 were annealed in N2O at various temperatures (700 °C - 1000 °C) for 30 sec. ARXPS showed that Si substrate at the Si-Si3N4 interface was oxidized when annealed at 1000 °C for 30 sec, and was accompanied by the oxidation of the top Si3N4 surface. The total film thickness increases 4–5 times of that of the original Si3N4 layer. However, the oxide formed on the top Si3N4 surface is twice as thick as that formed at the Si3N4/Si interface. No interfacial oxide was found when annealing below 900°C, although the formation of the silicon oxide and oxynitride above the Si3N4 layer was still observed.
MRS Proceedings. 12/1998; 567.
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ABSTRACT: We investigated Ta <sub> 2 </sub> O <sub> 5 </sub> films grown by chemical vapor deposition of Ta(N(CH <sub> 3 </sub> ) <sub> 2 </sub> ) <sub> 5 </sub> and O <sub> 2 </sub> both bare and SiO <sub>x</sub> N <sub>y</sub> -passivated Si(100) using x-ray photoelectron spectroscopy, time-of-flight secondary-ion-mass spectroscopy (TOF-SIMS), and electrical measurements. The SiO <sub>x</sub> N <sub>y</sub> -passivated layer was formed by nitric oxide exposure to the Si substrate. Chemical composition of the Ta <sub> 2 </sub> O <sub> 5 </sub> films is strongly dependent on the oxygen flow rate during film deposition; lower carbon levels and higher O/Ta ratios are observed for the films grown at higher O <sub> 2 </sub> flow rates. A corresponding leakage current decrease is observed for the films grown at a high O <sub> 2 </sub> flow rate. Compared to Ta <sub> 2 </sub> O <sub> 5 </sub> films deposited on bare Si(100), the films deposited on SiO <sub>x</sub> N <sub>y</sub> -passivated layers show better electrical properties; with smaller equivalent thickness (Δt<sub> eq </sub>∼6 Å), one order of magnitude lower leakage current was measured. TOF-SIMS data indicate that SiO <sub>x</sub> N <sub>y</sub> layers (∼9 Å) incorporate some oxygen during <-
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roman>Ta <sub> 2 </sub> O <sub> 5 </sub> deposition; however, regions where x=2, y=0 were not detected. Postdeposition annealing of Ta <sub> 2 </sub> O <sub> 5 </sub> /SiO <sub>x</sub> N <sub>y</sub> samples results in displacement of N by O in SiO <sub>x</sub> N <sub>y</sub> layers and oxidation of the Si substrate, forming SiO <sub> 2 </sub>. © 1998 American Vacuum Society.
Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 06/1998; · 1.25 Impact Factor
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ABSTRACT: Tantalum oxide films were deposited on Si substrates by chemical vapor deposition using the precursor Ta [ N(CH <sub> 3 </sub>)<sub>2</sub>]<sub>5</sub>, and an oxidizing agent— O <sub> 2 </sub>, H <sub> 2 </sub> O , or NO. Temperatures ranged between 400 and 500 °C and total pressures between 10<sup>-3</sup> and 9 Torr. NO did not lead to satisfactory film growth rates. Insignificant (≪1 at. %) N and up to a few percent C are incorporated when O <sub> 2 </sub> is the oxidant and the total pressure is in the Torr regime. In the milliTorr regime, the Ta <sub> 2 </sub> O <sub> 5 </sub> films, grown using either O <sub> 2 </sub> or H <sub> 2 </sub> O , contain readily detectable amounts of C and N. For the films grown with O <sub> 2 </sub> in the Torr regime, leakage currents were significantly lowered when the flow rate of O <sub> 2 </sub> increased from 100 to 900 sccm. © 1998 American Institute of Physics.
Applied Physics Letters 04/1998; · 3.84 Impact Factor
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ABSTRACT: Ultrathin (8–23 Å) silicon oxynitrides have been studied in the temperature range of 560–1000 °C in 4 Torr of NO using a sequential growth and analysis approach. X-ray photoelectron spectroscopy indicates that with increasing growth temperature and time, a bonding structure with predominantly Si–O rather than Si–N formation is favored. Simultaneously, the average volume fraction of N (N/N+O) in the dielectric decreases, as a consequence of which the N1s binding energy increases by 0.2–0.8 eV from its initial value of 397.8 eV at a thickness of 8 Å. A correlation of the electrical characteristics of NO grown oxynitrides with nitrogen content and location has been made. A film growth mechanism that takes into account the removal of previously incorporated N by NO is also proposed. © 1997 American Institute of Physics.
Applied Physics Letters 01/1997; 70(1):63-65. · 3.84 Impact Factor
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ABSTRACT: The nitridation of clean Si(100)‐2×1 with NO 2 has been studied using Auger electron spectroscopy (AES). In this letter we demonstrate that the interaction of Si(100) with NO 2 leads to the efficient incorporation of nitrogen (N) and oxygen (O) in single crystal Si as opposed to the case of N 2 O on Si(100). A comparative study of the incorporation efficiency of N and O by the reaction of NO 2 and N 2 O with Si(100) over a wide temperature range has been performed. It is observed that only a few Langmuirs (L) of NO 2 is required to saturate the Si surface while reaction with N 2 O is not as favorable. At temperatures ranging from room temperature to 1000 °C, varying proportions of N and O are incorporated into the Si by NO 2 . Repeated dosing and annealing cycles indicate that continued incorporation of N and O is possible even through a nitrogen‐rich Si layer.
Applied Physics Letters 10/1994; · 3.84 Impact Factor
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ABSTRACT: Effects of NH 3 nitridation on the chemical and electrical properties of N 2 O oxides have been studied. Compared with NH 3 ‐nitrided SiO 2 , NH 3 nitridation does not degrade the electrical properties of N 2 O oxides, thus resulting in superior impurity diffusion barrier properties, while preserving excellent interface immunity to hot‐carrier injection and much lower charge trapping. Correlation studies between the chemical and electrical properties of NH 3 ‐nitrided N 2 O and NH 3 ‐nitrided SiO 2 have been done to explain these results.
Applied Physics Letters 05/1994; · 3.84 Impact Factor
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ABSTRACT: The chemical structure and composition of ultrathin N 2 O oxides have been investigated using angle resolved x‐ray photoelectron spectroscopy and compared to those of reoxidized NH 3 ‐nitrided SiO 2 . It is found that N 2 O oxide shows a second nitrogen‐related bond (N—O bonds) in close proximity to the SiO 2 /Si interface in addition to the typically observed Si—N bonds in reoxidized NH 3 ‐nitrided SiO 2 . In addition, the change of the difference between Si 2p and O 1s binding energies in the N 2 O oxide and reoxidized NH 3 ‐nitrided SiO 2 with the take‐off angle is negligible due to the interfacial nitrogen incorporation.
Applied Physics Letters 03/1994; · 3.84 Impact Factor
