Vacuum Rapid Thermal Annealing Research Articles

Nanocluster evolution in Ge + ion implanted Ta 2O 5 layers

Ion implantation-induced nanoclusters were synthesized in reactive sputtered Ta 2O 5 films by Ge + implantation and subsequent annealing. The effects of ion fluence and post-implantation thermal treatment on the kinetics of the nanoclustering were investigated. Ge + ions with energy of 40 keV and fluences of 5 × 10 15, 1 × 10 16 and 5 × 10 16 cm − 2 were implanted in the Ta 2O 5 layers at room temperature. The samples were thermally treated by rapid thermal annealing in vacuum at 700 °C and 1000 °C for 30, 60 and 180 s. Structural studies of all samples were done by Cross-sectional Transmission Electron Microscopy in diffraction and phase contrast mode. Under optimized conditions (high implantation fluence, subsequent annealing) nanoclusters are formed around the projected ion range of the implanted Ge + ions. The structure of the implanted Ta 2O 5 matrix changes from amorphous to orthorhombic when the annealing was performed at 1000 °C. Although the Ta 2O 5 matrix crystallizes, no evidence is obtained for crystallization of the embedded nanoclusters even after annealing at 1000 °C.

Thermal stability of nitrided high-k dielectrics

The use of metal oxides and silicate films (high-k) on Si to replace SiO2 and SixNyOz as gate dielectrics in advanced CMOSFET technology presents several challenges, mainly concerning the chemical and structural stability of the high-k during the fabrication steps of microelectronic devices. Recent investigations indicated that incorporation of nitrogen into the high-k films provides substantial improvements on the direction of overcoming such difficulties. We report on the atomic transport and exchange of N, O, Si, Al, and Hf during thermal processing of AlON, HfSiO and HfSiN films on Si. All systems were submitted to rapid thermal annealing in vacuum or in 18O-enriched O2, as well as in combined, sequential thermal processing steps. The areal densities of the chemical species of interest were determined, before and after thermal processing, by nuclear reaction analysis and by Rutherford backscattering spectrometry. The profiles of the light elements were also monitored by narrow nuclear resonant reaction profiling with sub-nanometric depth resolution. In addition, we present some results on x-ray photoelectron spectroscopy and low energy ion spectroscopy. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Thermal stability of plasma-nitrided aluminum oxide films on Si

The effect of post-deposition rapid thermal annealing in vacuum and in dry O2 on the stability of remote plasma-assisted nitrided aluminum oxide films on silicon is investigated. The areal densities of Al, O, N, and Si were determined by nuclear reaction analysis and their concentration versus depth distributions by narrow nuclear reaction resonance profiling, with subnanometric depth resolution. Annealing in both vacuum and O2 atmospheres produced partial loss of N from the near-surface regions of the films and its transport into near-interface regions of the Si substrate. Oxygen from the gas phase was incorporated in the AlON films in exchange for O and N previously existing therein, as well as in the near-interface regions of the Si substrate, leading to oxynitridation of the substrate. Al and Si remained essentially immobile under rapid thermal processing, confirming that the presence of nitrogen improves the thermal stability characteristics of the AlON/Si structures in comparison with non-nitrided Al2O3/Si.

Atomic Transport and Chemical Stability during Annealing of UltrathinAl2O3Films on Si

Ultrathin films of Al2O3 deposited on Si were submitted to rapid thermal annealing in vacuum or in oxygen atmosphere, in the temperature range from 600 to 800 degrees C. Nuclear reaction profiling with subnanometric depth resolution evidenced mobility of O, Al, and Si species, and angle-resolved x-ray photoelectron spectroscopy revealed the formation of Si-Al-O compounds in near-surface regions, under oxidizing atmosphere at and above 700 degrees C. Under vacuum annealing all species remained essentially immobile. A model is presented based on diffusion-reaction equations capable of explaining the mobilities and reproducing the obtained profiles.

Effects of rapid thermal annealing in vacuum on electrical properties of thin Ta2O5–Si structures

The effect of rapid thermal annealing (RTA) in vacuum (1273K) on the properties of thin thermal Ta2O5 films in dependence on the oxidation temperature (673–873K) has been studied. It is established that the electrical and dielectric properties of the annealed layers are rather strong function of the oxidation temperature than of the film thickness. RTA reduces the leakage current of layers oxidized at 673 and 773K and deteriorates the current for layers formed at 823 and 873K—in both the cases the effect is stronger for shortest annealing time. The leakage current level after annealing of the lower-oxidation temperature layers is comparable with that of the as-grown high temperature oxidized films. The effect of RTA on the dielectric constant and fixed oxide charge is complex and there is not a simple relation with the leakage current behaviour—the annealing is not beneficial for fixed oxide charge in poorly oxidized films at 673 and 773K. The results are discussed in terms of oxidation and crystallization effects during the annealing in the oxygen free ambient and their relation with the properties of the initial Ta2O5–Si structures.

Formation of MoSi 2 by rapid thermal annealing in vacuum of CVD – Mo films on silicon substrate

Silicide formation due to thermal treatment of thin (200–1000 Å) molybdenum films on single-crystal silicon substrates in the temperature range of 800–1000°C was studied. Rapid thermal annealing (RTA) in vacuum was performed on Mo/Si system to form silicides. Molybdenum films were deposited on Si (1 0 0) by chemical vapor deposition (CVD), using Mo(CO) 6 (molybdenum hexacarbonyl) as precursor. The as-deposited films with thicknesses of 200 and 1000 Å were heated in vacuum at RTA temperatures of 800 and 1000°C for time durations of 15 and 30 s, 1 and 3 min. The results from the X-ray diffraction analysis and the Reflection Infrared Spectroscopy measurements show that Mo films after annealing transform into Mo silicides, preferably tetragonal MoSi 2 crystal phase. The presence of Mo 5Si 3 formation is also found. There is a change in the electrical resistance of the films before and after annealing. For the molybdenum silicides obtained the resistivity is in the range 0.9–9.8 mΩ cm.

Effect of vacuum rapid thermal annealing on the properties of SiN x films

Silicon nitride films prepared by different chemical vapor deposition techniques (APCVD, PECVD, μPCVD, LPCVD) are submitted to rapid thermal annealing (RTA) in vacuum at 800–1400°C for different time intervals of 15–180 s. The samples have been characterized by infra red (IR) spectroscopy and by capacitance–voltage ( C– V) measurements before and after RTA. The effect of the RTA on the IR spectra is the gradual shift of the maximum of the Si–N band from 826 to 833.2 cm −1. The RHEED spectra show that α-crystalline phase appears in the SiN layers after the RTA treatment.

Thin CNx films prepared by vacuum rapid thermal annealing

The properties of thin CN x layers prepared by rapid thermal annealing (RTA) are compared with CN xlayers obtained from N 2 plasma treatment. Carbon films of 6000 Å thickness were deposited by magnetron sputtering system on p-type silicon substrates. The samples were treated in an RTA system in N 2 atmosphere at a temperature above 800̊C. Some of the samples were treated in an N 2 plasma. The resulting CN x layers were analyzed by XPS (X-ray photoelectron spectroscopy) technique. The concentration of the incorporated nitrogen and carbon in the layer depths were analyzed by consecutive etching and measurement of the XPS spectra. This showed that maximum depth of incorporated nitrogen atoms in the carbon layer after 800̊C, 1 min RTA in N 2 was about 100 A ̊ , while in the N 2 plasma treated samples a nitrogen concentration of 6% was observed at 150 A ̊ . The electrical resistance of the layers rose with increase of the nitrogen concentration in the layers. © 1998 Elsevier Science Ltd. All rights reserved

Influence of vacuum rapid thermal annealing on some properties of quartz resonators

The influence of rapid thermal annealing (RTA) on the parameters of quartz resonators and their amplitude–frequency characteristics has been investigated. The resonators were an AT-cut quartz substrate with Al-electrodes 120 nm thick deposited by electron beam evaporation at 1.10 −5 mbar. The samples were subjected to RTA at the temperature of the heater 700°C, 800°C and 900°C for a time from 15 s to 180 s in vacuum at 5.10 −5 mbar. A correlation between the electrical parameters of the resonators and their amplitude–frequency characteristics from one side and RTA conditions from another side have been established. The conditions under which the quartz resonators parameters were improved have been found.

Properties of palladium silicide thin films obtained by vacuum rapid thermal annealing of r.f. sputtered Pd films on Si

The possibility of obtaining palladium silicide layers by rapid thermal annealing (RTA) has been studied. Palladium layers of 300 and 1000 Å thicknesses were deposited by r.f. sputtering on Si substrates. The samples were subjected to RTA at 800, 1000, 1200 and 1400°C for 15 s, 30 s, 1 min and 3 min in vacuum 5×10 −5 Torr. The deposited structure was studied by RHEED. The dependence of the structure and the sheet resistance of the Pd–Si films, as a function of the RTA condition, was established. The sample temperature in the RTA system could be increased from room temperature to the working temperature (800–1400°C) in 2 s. Pd 2Si was formed after annealing at 1400°C even for short times of 15 s.

Influence of the rapid thermal annealing in vacuum on the XPS characteristics of thin SiO 2

The effect of rapid thermal annealing (1073–1473 K) in vacuum on thin (11 nm) thermal SiO 2 layers on Si has been studied by means of X-ray photoelectron spectroscopy. The results show that the RTA slightly affects the properties of the SiSiO 2 system up to a temperature of 1473 K and the effect is in the direction of obtaining a more perfect oxide structure. The stoichiometry of the layer, however, at the surface as well as in the bulk is not influenced by the annealing. The analysis of the data also shows that the spontaneous decomposition of the oxide and the pinholes formation most likely take place during the annealing at 1473 K. The results seem to rule out the formation of suboxides at this temperature.

Influence of vacuum rapid thermal annealing on the properties of Al and Ag films on quartz

The influence of rapid thermal annealing of 700 °C and 800 °C in 5 × 10 −5 mbar vacuum on the structure and morphology of aluminum and silver thin films, deposited on quartz substrates is investigated. The metal films studied have thicknesses of 200 nm and 120 nm for Al and Ag, respectively, when the annealing time ranges from 5 to 180s. A recrystallization process in the Al films is observed. A correlation between the annealing time and the equivalent parameters' change of the quartz resonators with silver electrodes is also found.

The effect of rapid thermal annealing in vacuum on the properties of thin SiO2 films

The influence of rapid thermal annealing in vacuum on the properties of thermally grown SiO2 has been investigated by means of high-field Fowler-Nordheim tunnelling injection and breakdown field techniques. The results indicate that the rapid thermal annealing process anneals the original electron traps in the oxide but at the same time introduces a positive charge. These two mechanisms are a strong function of the technological history of the samples and of the oxide quality. Rapid thermal annealing in vacuum improves the properties of the as-grown oxides without conventional post-oxidation annealing in N2 but degrades the oxides that are preliminarily annealed in N2. The extent of the improvement (degradation) depends on the temperature of rapid annealing (1073-1473 K).

Self‐Aligned Titanium Silicided Junctions Formed by Rapid Thermal Annealing in Vacuum

New self‐aligned silicided junctions have been developed by rapid thermal annealing in vacuum for applications to VLSI technology. These silicided junctions were investigated in regard to sheet resistance, junction depth, junction leakage current, and impurity depth profiles. After Ti film (35 nm) was deposited by dc magnetron sputtering, Si+ was implanted for interface mixing and rapid thermal annealing (RTA) in vacuum (∼10−1 Pa) were performed in temperature range of 550°–750°C. In these temperature ranges, the lateral growth of titanium silicide was prevented. After Si+ implantation through the titanium silicide layer to amorphize the Si substrate, As+ and B+ ions were implanted for n+/p junction, and p+/n junction, respectively. Finally furnace annealing (900°C, 30 min) was performed with a cap CVD oxide. We have successfully fabricated the silicided junctions with the junction depth of 0.12 μm, and the leakage current of (at reverse bias of 5.0V) for n+/p junction and of 0.14 μm, and of for p+/n junction.