A comparative study of atomic layer deposited advanced high-k dielectrics

A comparative electrical characterization of metal-insulator-semiconductor (MIS) structures fabricated from atomic layer deposited (ALD) Al/sub 2/O/sub 3/, Ta/sub 2/O/sub 5/ and Nb/sub 2/O/sub 5/-Ta/sub 2/O/sub 5/-Nb/sub 2/O/sub 5/ dielectric thin films on silicon substrates has been carried out. The interface states as well as defects inside the insulator bulk were measured by using capacitance-voltage (C-V), deep level transient spectroscopy (DLTS) and conductance-transient (G-t) techniques. Interface quality is poorer in the case of Ta/sub 2/O/sub 5/ (D/sub it/ is about 6 /spl times/ 10/sup 12/ cm/sup -2/ eV/sup -1/) than in the Al/sub 2/O/sub 3/ ones (D/sub it/ values up to 1 /spl times/ 10/sup 12/ cm/sup -2/ eV/sup -1/). Also, the addition of Nb/sub 2/O/sub 5/ buffer layers to Ta/sub 2/O/sub 5/-based MIS degrades the structure (D/sub it/ reaches values of 1.2 /spl times/ 10/sup 13/ cm/sup -2/ eV/sup -1/).