Electrical properties of HfO2/Al2O3 dielectrics fabricated on In0.53Ga0.47As by using atomic layer deposition at low temperatures (100 - 200 ◦C)

Electrical properties of the HfO2/Al2O3 dielectrics stacked using single- and dual-temperature atomic-layer deposition processes on In0.53Ga0.47As

“…Correspondingly, the amount of frequency dispersion exhibited a negligible change in all the samples after the increase in the measurement temperature to 100 °C, as shown in figure 4. Consistent with the previous single-temperature process results [15], the lowest amount of border traps were achieved from the 100/100 sample as compared to the 300/300 sample processed at a higher temperature. When the ALD temperature for the interfacial Al 2 O 3 layer was fixed at 100 °C, the increase in the ALD temperature for the subsequent HfO 2 film resulted in an increase in FD acc , while the dual-temperature-processed 100/300 sample presented a similar FD acc value as the singletemperature-processed 300/300 sample.…”

“…First, the ALD temperature-dependent C−V characteristics were evaluated through comparison of the CET values, which were obtained from the maximum capacitance (C max ) measured at the lowest frequency of 100 Hz. According to our previous results [15], a decrease in the ALD temperature from 300 to 100 °C reduces the dielectric constants for both HfO 2 and Al 2 O 3 films, which eventually results to a corresponding increase in the CET value of a stacked structure for a singletemperature process. As shown in figure 3, this result was confirmed again through comparison of the CET values for the single-temperature processed samples (100/100 and 300/300 samples with a similar physical thickness).…”

“…Meanwhile, when the ALD temperature for Al 2 O 3 remained constant at 100 °C, an increase in the HfO 2 ALD temperature for the dual-temperature process allowed for a continuous decrease in CET, even considering the difference in thickness between samples (refer to figure 1). This phenomenon is believed to be mostly as a result of a corresponding increase in the dielectric constant through an increase in the film densities (including the possible partial crystallization of HfO 2 ) and/or by the reduction in the number of residual impurities [15].…”

“…trimethylaluminum (TMA)), has proved to be effective in in situ self-cleansing of the native oxide at high ALD temperatures [8]. However, due to the relatively low dielectric constant of Al 2 O 3 , a HfO 2 gate dielectric stacked with an ultra-thin Al 2 O 3 passivation layer is considered as a promising candidate for In 1-x Ga x As MOSFETs [9][10][11][12][13][14][15].…”

“…Recently, we examined the electrical properties of the HfO 2 /Al 2 O 3 stacked dielectrics formed at a relatively low temperature regime (100 °C-200 °C), and showed that fewer near-interface traps in addition to a lower leakage current could be achieved through reduction of the deposition temperatures for both HfO 2 and Al 2 O 3 layers down to 100 °C regardless of a much lower self-cleaning efficiency during the Al 2 O 3 deposition process [15]. As an adverse effect, the capacitance-equivalent oxide thickness (CET) was significantly increased for the single-temperature process at 100 °C as a result of the simultaneous decrease in the dielectric constants of both HfO 2 and Al 2 O 3 layers [15]. In this study, to compensate for the undesirable increase in CET, we investigated the pros and cons of the dualtemperature process for the formation of HfO 2 /Al 2 O 3 stacked dielectrics on the n-type In 0.53 Ga 0.47 As substrates.…”