Infrared study on room-temperature atomic layer deposition of HfO2 using tetrakis(ethylmethylamino)hafnium and remote plasma-excited oxidizing agents

Abstract

Room-temperature atomic layer deposition (ALD) of HfO2 was examined using tetrakis (ethylmethylamino)hafnium (TEMAH) and remote plasma-excited water and oxygen. A growth rate of 0.26 nm/cycle at room temperature was achieved, and the TEMAH adsorption and its oxidization on HfO2 were investigated by multiple internal reflection infrared absorption spectroscopy. It was observed that saturated adsorption of TEMAH occurs at exposures of ∼1 × 105 L (1 L = 1 × 10−6 Torr s) at room temperature, and the use of remote plasma-excited water and oxygen vapor is effective in oxidizing the TEMAH molecules on the HfO2 surface, to produce OH sites. The infrared study suggested that Hf–OH plays a role as an adsorption site for TEMAH. The reaction mechanism of room temperature HfO2 ALD is discussed in this paper.

Room-temperature atomic layer deposition of ZrO2 using tetrakis(ethylmethylamino)zirconium and plasma-excited humidified argon

“…In our previous study, the room-temperature HfO 2 ALD was developed by using TEMAH and the plasma excited humidified oxygen (water vapor and oxygen) [20]. In this study, it was reported that TEMAH, having a similar chemical structure to TEMAZ, has a saturation behavior on hydroxylated HfO 2 surfaces with its exposure of 1.0 ×10 5 L. We can say that TEMAZ and TEMAH have almost the same adsorption characteristics in RT ALD.…”

“…As we can see in the previous studies for the adsorption sites [19,20], the hydroxyl groups are expected as the adsorption sites. We monitored the absorbance of the surface hydroxyl group by MIR-IRAS for the TEMAZ and plasma treatments as shown in Fig.…”

“…2 [20,24]. The peak at 2931 cm -1 can be assigned to the -CH 2 groups [20,24]. The peak at 2781 cm -1 comes from the symmetrical stretching vibration of -N(C 2 H 5 )(CH 3 ) [20,24].…”

“…The peak at 2931 cm -1 can be assigned to the -CH 2 groups [20,24]. The peak at 2781 cm -1 comes from the symmetrical stretching vibration of -N(C 2 H 5 )(CH 3 ) [20,24]. To confirm the saturated adsorption, absorbance of C-H at 2869 cm -1 as a function of the TEMAZ exposure is shown in Fig.…”

“…With the plasma excited humidified argon, we also developed the RT ALD of TiO 2 with a precursor of tetrakis(dimethylamino)titanium [19]. On the other hand, we also tried to achieve the RT ALD of HfO 2 with tetrakis(ethylmethylamino)hafnium (TEMAH) although we found that plasma excited humidified argon was ineffective [20].…”