The Effect of Film Thickness on the C40 TiSi[sub 2] to C54 TiSi[sub 2] Transition Temperature

Abstract

In this paper, we investigate the transformation of TiSi 2 from the high-resistivity C40 phase to the low-resistivity C54 phase. In particular, the effect of C40 film thickness on the transition temperature, which has not been studied in the literature, is scrutinized. Two types of laser, i.e., Nd:YAG ͑yttrium aluminum garnet͒ and excimer laser, were used to induce C40 TiSi 2 on samples of 350 Å of Ti deposited on ͑100͒ Si substrates. It was also found that the thicker C40 TiSi 2 ͑40 nm͒ induced by the Nd:YAG laser required a very high temperature of more than 1000°C and an activation energy of 6.5 eV for the formation of the stable C54 TiSi 2 , whereas a thinner C40 TiSi 2 ͑15 nm͒ produced by the excimer laser required a low temperature of 700°C and an activation energy of 2.5 eV to transform into C54 TiSi 2 . The much lower transition temperature for the thin samples is attributed to the compressive strain in these samples.

Impact of nanosecond laser energy density on the C40-TiSi2 formation and C54-TiSi2 transformation temperature

“…12), the C40-TiSi2 thickness after UV-NLA (and before RTA) enabling the formation of C54-TiSi2 only (ED = 0.85 J/cm²) is close to 3 nm. This thickness is significantly lower than the C40-TiSi2 layer thickness determined by Tan et al 60 . However, they show that the enhancement of the C54-TiSi2 phase from the C40-TiSi2 one is strongly dependent on the thickness of the C40-TiSi2 layer.…”

“…However, they show that the enhancement of the C54-TiSi2 phase from the C40-TiSi2 one is strongly dependent on the thickness of the C40-TiSi2 layer. In their study 60 , a thick layer of C40-TiSi2 around 40 nm is undesirable because a higher thermal budget is needed to enable the transformation. On the contrary, a thin layer of C40-TiSi2 (around 15 nm in their case) allows to achieve the C40-C54 transformation at low thermal budget.…”