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Study of Ta2O5 based MOS capacitors, with tantalum oxidized in O-2 : NH3 ambient

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Title Study of Ta2O5 based MOS capacitors, with tantalum oxidized in O-2 : NH3 ambient
 
Creator KRISHNAMOORTHI, P
CHANDORKAR, AN
 
Subject thin-films
 
Description Tantalum Pentaoxide, an alternative to SiO2, as a high-k dielectric for DRAM and MOS applications, faces the problem of interface mismatch at silicon. SiO2 or Si3N4 interfacial layer could help in overcoming this problem. The higher band offsets of these materials also help in the reduction of leakage currents at low electric fields. Here we study the physical and electrical characteristics of Ta, oxidized in O-2:NH3 ambient, and without any other interface layer. This is done to check if N/H moves to the interface, and thus improves the electrical properties. XRD studies of the film, showed the presence of Ta2O5. Peaks corresponding to TaSi2, un-oxidized tantalum and TaN were also found in the film. But the intensity of these peaks decreased with the reduction of NH3 content. Thus a higher oxygen content could reduce the content of TaN and unoxidized tantalum. FTIR analysis however showed strong Ta=O and Si-O peaks. For the MOS capacitors, due to the presence of resistive components, the maximum capacitance was reduced, compared to that of pure Ta2O5 films. Oxide charges in the films were observed to be around 1.9E10 cm(-2). But the traps in these films were found to be almost negligible as observed from the negligible hysteresis in the C-V characteristics. Films with N/H showed lesser oxide charges by an order of magnitude, as compared to pure Ta2O5 films.
 
Publisher MATERIALS RESEARCH SOCIETY
 
Date 2011-10-23T09:55:18Z
2011-12-15T09:11:05Z
2011-10-23T09:55:18Z
2011-12-15T09:11:05Z
2002
 
Type Proceedings Paper
 
Identifier SILICON MATERIALS-PROCESSING, CHARACTERIZATION AND RELIABILITY,716,525-530
1-55899-652-4
0272-9172
http://dspace.library.iitb.ac.in/xmlui/handle/10054/15095
http://hdl.handle.net/100/1844
 
Source Symposium on Silicon Materials held at the 2002 MRS Spring Meeting,SAN FRANCISCO, CA,APR 01-05, 2002
 
Language English