Transmission electron microscopy investigation of the formation of C54-TiSi(2) phase on stressed (001)Si.
The effects of stress on the formation of C54-TiSi2 phase in Ti/(001)Si samples have been investigated by high-resolution transmission electron microscopy in conjunction with auto-correlation function (ACF) analysis. The C54-TiSi2 phase transformation temperature in tensily stressed samples was found to be lowered by about 100 degrees C than that in compressively stressed samples. The thickness of amorphous interlayers (a-interlayers) between Ti metal thin films and Si substrates was found to be thicker and thinner in the tensily and compressively stressed Si samples, respectively. Furthermore, the thicker a-interlayer was found to consist of a higher density of crystallites from the ACF analysis. With a higher density of crystallites in the a-interlayer, the grain size of C49-TiSi2 was reduced since more nucleation sites are available for the formation of C49-TiSi2. The small grain size of C49-TiSi2 in turn enhances the formation of C54-TiSi2. As a result, the phase transformation of C49- to C54-TiSi2 is enhanced by the tensile stress present in silicon substrates.
Cheng
S L
SL
Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan, ROC.
Chang
S M
SM
Huang
H Y
HY
Chen
L J
LJ
Tsai
C J
CJ