skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Effect of composition on the thermal stability of sputter deposited hafnium aluminate and nitrided hafnium aluminate dielectrics on Si (100)

Abstract

Hafnium aluminate (HfAlO) and nitrided hafnium aluminate (HfAlON) dielectrics were sputter deposited on Si (100) substrate. The N{sub 2}/(N{sub 2}+Ar) flow ratio was varied between 0 and 66.6% in order to vary the nitrogen concentration. The Hf/Al ratio was varied from 0.5 to 1. In situ x-ray photoelectron spectroscopy and electrical measurements were utilized to characterize the as-deposited HfAlO and HfAlON films. The thermal stability studies of the HfAlO and HfAlON thin films after a 1000 deg. C, 10 s argon rapid thermal anneal were performed using grazing incidence x-ray diffraction and backside secondary ion mass spectrometry. Suppression of crystallization and no detectible outdiffusion of hafnium and aluminum into the silicon substrate were seen for HfAlO and HfAlON thin films with a Hf/Al ratio of 0.5.

Authors:
; ; ; ;  [1]
  1. Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080 (United States)
Publication Date:
OSTI Identifier:
20979420
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 11; Other Information: DOI: 10.1063/1.2743818; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINATES; ALUMINIUM; ANNEALING; ARGON; CRYSTALLIZATION; DIELECTRIC MATERIALS; HAFNIUM COMPOUNDS; MASS SPECTRA; MASS SPECTROSCOPY; NITRIDATION; NITROGEN; SILICON; SUBSTRATES; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 1000-4000 K; THIN FILMS; TIME DEPENDENCE; X-RAY DIFFRACTION; X-RAY PHOTOELECTRON SPECTROSCOPY

Citation Formats

Sivasubramani, P., Kim, J., Kim, M. J., Gnade, B. E., and Wallace, R. M.. Effect of composition on the thermal stability of sputter deposited hafnium aluminate and nitrided hafnium aluminate dielectrics on Si (100). United States: N. p., 2007. Web. doi:10.1063/1.2743818.
Sivasubramani, P., Kim, J., Kim, M. J., Gnade, B. E., & Wallace, R. M.. Effect of composition on the thermal stability of sputter deposited hafnium aluminate and nitrided hafnium aluminate dielectrics on Si (100). United States. doi:10.1063/1.2743818.
Sivasubramani, P., Kim, J., Kim, M. J., Gnade, B. E., and Wallace, R. M.. Fri . "Effect of composition on the thermal stability of sputter deposited hafnium aluminate and nitrided hafnium aluminate dielectrics on Si (100)". United States. doi:10.1063/1.2743818.
@article{osti_20979420,
title = {Effect of composition on the thermal stability of sputter deposited hafnium aluminate and nitrided hafnium aluminate dielectrics on Si (100)},
author = {Sivasubramani, P. and Kim, J. and Kim, M. J. and Gnade, B. E. and Wallace, R. M.},
abstractNote = {Hafnium aluminate (HfAlO) and nitrided hafnium aluminate (HfAlON) dielectrics were sputter deposited on Si (100) substrate. The N{sub 2}/(N{sub 2}+Ar) flow ratio was varied between 0 and 66.6% in order to vary the nitrogen concentration. The Hf/Al ratio was varied from 0.5 to 1. In situ x-ray photoelectron spectroscopy and electrical measurements were utilized to characterize the as-deposited HfAlO and HfAlON films. The thermal stability studies of the HfAlO and HfAlON thin films after a 1000 deg. C, 10 s argon rapid thermal anneal were performed using grazing incidence x-ray diffraction and backside secondary ion mass spectrometry. Suppression of crystallization and no detectible outdiffusion of hafnium and aluminum into the silicon substrate were seen for HfAlO and HfAlON thin films with a Hf/Al ratio of 0.5.},
doi = {10.1063/1.2743818},
journal = {Journal of Applied Physics},
number = 11,
volume = 101,
place = {United States},
year = {Fri Jun 01 00:00:00 EDT 2007},
month = {Fri Jun 01 00:00:00 EDT 2007}
}
  • The thermal stability of nanocomposite W-Si-N coatings, which had been sputter deposited at increased silicon target currents, was studied by annealing at 800 or 900 deg. C in vacuum by using x-ray diffraction, x-ray photoelectron spectroscopy, electron probe microanalysis, scanning electron microscopy, atomic force microscopy, and microhardness testing. The crystalline W{sub 2}N coatings were decomposed to W with the loss of interstitial N atoms and the presence of microcracks at their surfaces after annealing at 900 deg. C. The coating consisting of nanocrystalline (nc-) W{sub 2}N imbedded in amorphous (a-) Si{sub 3}N{sub 4} matrices and the amorphous coatings underwent partialmore » recrystallization, the loss of interstitial N atoms, and morphological changes upon annealing. The nc-W{sub 2}N/a-Si{sub 3}N{sub 4} coating had the least N in grain boundaries and the lowest atomic O/N ratio, and it had no failure after annealing at 900 deg. C, showing high thermal stability. The hardness of the coatings was decreased, but the nc-W{sub 2}N/a-Si{sub 3}N{sub 4} coating maintained the highest hardness (46.6{+-}3.7 GPa) after annealing at 900 deg. C.« less
  • The authors have examined the thermal stability of amorphous, molecular beam deposited lanthanum scandate dielectric thin films on top of Si (100) after a 1000 deg. C, 10 s rapid thermal anneal. After the anneal, crystallization of LaScO{sub 3} is observed. Excellent suppression of lanthanum and scandium diffusion into the substrate silicon is indicated by the back-side secondary ion mass spectrometry (SIMS) analyses. In contrast, front-side SIMS and high-resolution electron energy loss analyses of the amorphous Si/LaScO{sub 3}/Si (100) stack indicated the outdiffusion of lanthanum and scandium into the silicon capping layer during the anneal.
  • The band alignment of atomic layer deposited (HfZrO{sub 4}){sub 1−x}(SiO{sub 2}){sub x} (x = 0, 0.10, 0.15, and 0.20) gate dielectric thin films grown on Si (100) was obtained by using X-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy. The band gap, valence band offset, and conduction band offset values for HfZrO{sub 4} silicate increased from 5.4 eV to 5.8 eV, from 2.5 eV to 2.75 eV, and from 1.78 eV to 1.93 eV, respectively, as the mole fraction (x) of SiO{sub 2} increased from 0.1 to 0.2. This increase in the conduction band and valence band offsets, as a function of increasing SiO{sub 2} mole fraction,more » decreased the gate leakage current density. As a result, HfZrO{sub 4} silicate thin films were found to be better for advanced gate stack applications because they had adequate band gaps to ensure sufficient conduction band offsets and valence band offsets to Si.« less
  • We report on the stability under rapid thermal annealing (RTA) of the nitrogen depth profile in nitrided HfO{sub 2}/SiO{sub 2}/Si[001] and Hf{sub 0.8}Si{sub 0.2}O{sub 2}/SiO{sub 2}/Si[001] dielectric stacks. High resolution x-ray photoelectron spectroscopy (XPS) data indicate that the chemical component of nitrogen associated with the hafnium layer (binding energy of 396.7 eV) decreases considerably upon RTA. This was accompanied by a corresponding increase in the nitrogen component associated with silicon oxynitride (binding energy of 397.5 eV). A self-consistent analysis of the angle resolved XPS data indicated that the total amount of nitrogen in the film remains constant, suggesting that RTAmore » causes an exchange of nitrogen between the hafnium and silicon layers. Transmission electron microscopy images show crystallization of the hafnium layer upon RTA, which is consistent with the loss of nitrogen. Data from time of flight secondary ion mass spectroscopy were consistent with the change in the nitrogen profile caused by RTA.« less
  • Precisely figured optics coated with high-reflectance multilayer films are an integral part of an extreme ultraviolet (EUV) projection lithography system. Since multilayer film stress deforms these precisely figured optics, it is important that this stress be characterized and that suitable methods are developed to negate the effects of the stress. However, these techniques must reduce or compensate for the effects of film stress without significantly reducing the EUV reflectivity, since the reflectivity has a strong impact on the throughput of an EUV lithography system. Different techniques for reducing multilayer stress are examined. The technique of varying the base pressure (impuritymore » level) yielded a 10{percent} decrease in stress with a 2{percent} decrease in reflectance for our multilayers. A study of annealing during Mo/Si deposition is performed; a stress reduction of 70{percent} is observed at 200{degree}C, similar to what has been found for postdeposition annealing. However, the reflectance loss was 3.9{percent} versus 1.3{percent} for postdeposition annealing, indicating that if annealing is performed on our films it should be done after multilayer deposition. A decrease of approximately 9{percent} in the bilayer period thickness was observed for annealing during deposition at temperatures near 120 to 140{degree}C, much larger than the thickness changes observed during postdeposition annealing. A new athermal buffer-layer technique is developed to compensate for the effects of stress. Using this technique with amorphous silicon and Mo/Be buffer layers it is possible to obtain Mo/Be and Mo/Si multilayer films with a near zero net film stress and less than a 1{percent} degradation in reflectivity. It is important that the multilayer coated optics are stable with time and that the stress reduction and compensation techniques do not degrade the stability. The temporal stability of 100-nm-thick Mo, Si, and Be single-layer films, Mo/Si and Mo/Be multilayer films, and films treated with various stress reduction/compensation techniques are investigated. Results are reported showing the reflectance peak wavelength to be stable to within 0.15{percent} for both the multilayers and the stress-compensated multilayers. Therefore, stability is maintained when these buffer-layer stress compensation techniques are applied. Mo/Si multilayer films exhibit a {approximately}10{percent} short-term decrease in the stress over the first few months after deposition, but the stress stabilizes thereafter. The Mo/Si reflectance is observed to be stable to within 0.4{percent} over a period of over 400 days. The Mo/Be multilayer film stress was stable to within about 2{percent} over 300 days, and the reflectance was observed to decrease by about 1.5{percent} over the same period. For Mo/Si on a Mo/Be buffer layer the stress changed from {minus}28 to +3 MPa, and the reflectance decreased by approximately 0.4{percent} for a period of over 300 days. For Mo/Be on an a-Si buffer layer, the stress changed from {minus}23 to {minus}3 MPa, and the reflectance decreased by {approximately}1.8{percent} for a period of over 300 days; this drop in reflectance is believed to be due primarily to the Mo/Be and not the addition of the buffer layer. {copyright} {ital 1999 Society of Photo-Optical Instrumentation Engineers.}« less