TY - JOUR
T1 - In situ spectroscopic ellipsometry analyses of hafnium diboride thin films deposited by single-source chemical vapor deposition
AU - Yang, Yu
AU - Jayaraman, Sreenivas
AU - Sperling, Brent
AU - Kim, Do Young
AU - Girolami, Gregory S.
AU - Abelson, John R.
N1 - Funding Information:
The authors are grateful to the National Science Foundation for support of this research under Grant Nos. NSF CH-00-76061, NSF DMR-03-54060, and NSF DMR-03-15428. Compositional and structural analyses of the films were carried out in the Center for Microanalysis of Materials, University of Illinois, which is partially supported by the U.S. Department of Energy under Grant No. DEFG02-91-ER45439. The authors also thank Leslie H. Allen at UIUC for the use of his four-point probe apparatus.
PY - 2007
Y1 - 2007
N2 - In situ spectroscopic ellipsometry was used to analyze hafnium diboride thin films deposited by chemical vapor deposition from the single-source precursor Hf (B H4) 4. By modeling the film optical constants with a Drude-Lorentz model, the film thickness, surface roughness, and electrical resistivity were measured in situ. The calculated resistivity for amorphous films deposited at low temperature ranged from 340 to 760 μ cm. These values are within 25% of those measured ex situ with a four-point probe, indicating the validity of the optical model. By modeling the real-time data in terms of film thickness and surface roughness, the film nucleation and growth morphology were determined as a function of substrate type, substrate temperature, and precursor pressure. The data show that at low precursor pressures (∼ 10-6 Torr) and at low substrate temperatures (<300 °C), the onset of growth is delayed on both Si and Si O2 surfaces due to the difficulty of nucleation. A higher substrate temperature or precursor pressure reduces this delay. At low temperatures the film morphology is a sensitive function of the precursor pressure because site-blocking effects change the reaction probability; the authors show that the morphology of newly grown film can be reversibly transformed from dense smooth to rough columnar by decreasing the precursor pressure.
AB - In situ spectroscopic ellipsometry was used to analyze hafnium diboride thin films deposited by chemical vapor deposition from the single-source precursor Hf (B H4) 4. By modeling the film optical constants with a Drude-Lorentz model, the film thickness, surface roughness, and electrical resistivity were measured in situ. The calculated resistivity for amorphous films deposited at low temperature ranged from 340 to 760 μ cm. These values are within 25% of those measured ex situ with a four-point probe, indicating the validity of the optical model. By modeling the real-time data in terms of film thickness and surface roughness, the film nucleation and growth morphology were determined as a function of substrate type, substrate temperature, and precursor pressure. The data show that at low precursor pressures (∼ 10-6 Torr) and at low substrate temperatures (<300 °C), the onset of growth is delayed on both Si and Si O2 surfaces due to the difficulty of nucleation. A higher substrate temperature or precursor pressure reduces this delay. At low temperatures the film morphology is a sensitive function of the precursor pressure because site-blocking effects change the reaction probability; the authors show that the morphology of newly grown film can be reversibly transformed from dense smooth to rough columnar by decreasing the precursor pressure.
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U2 - 10.1116/1.2409939
DO - 10.1116/1.2409939
M3 - Article
AN - SCOPUS:33846195075
VL - 25
SP - 200
EP - 206
JO - Journal of Vacuum Science and Technology A
JF - Journal of Vacuum Science and Technology A
SN - 0734-2101
IS - 1
ER -