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Investigation of Crystallization Processes from Hafnium Silicate Powders Prepared from an Oxychloride Sol‐Gel
Author(s) -
McGilvery Catriona M.,
Gendt Stefan,
Payzant E. Andrew,
MacKenzie Maureen,
Craven Alan J.,
McComb David W.
Publication year - 2012
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2012.05408.x
Subject(s) - crystallization , materials science , nucleation , amorphous solid , hafnium , chemical engineering , silicate , phase (matter) , diffusion , dielectric , layer (electronics) , mineralogy , crystallography , metallurgy , nanotechnology , chemistry , zirconium , optoelectronics , thermodynamics , physics , organic chemistry , engineering
Hafnium oxide and silicate materials are now incorporated into working CMOS devices; however, the crystallization mechanism is still poorly understood. In particular, addition of SiO 2 to HfO 2 has been shown to increase the crystallization temperature of HfO 2 , hence, allowing it to remain amorphous under current processing conditions. Building on earlier study, we herein, investigate bulk Hf x Si 1− x O 2 samples to determine the effect of SiO 2 on the crystallization pathway. Techniques, such as XRD , HTXRD , thermal analysis techniques and TEM are used. It is found that the addition of SiO 2 has very little affect on the crystallization path at temperatures below 900°C, but at higher temperatures, a second t ‐ HfO 2 phase nucleates and is stabilized due to the strain of the surrounding amorphous SiO 2 material. With an increase in SiO 2 content, the temperature at which this nucleation and stabilization occurs is increased. The effect of strain has implications for inhibiting the crystallization of the high‐ k layer, reduction of grain boundaries and hence diffusion, reduction of formation of interface layers and the possibility of stabilizing t ‐ HfO 2 rather than m ‐ HfO 2 , hence, increasing the dielectric of the layer.