Properties of Atomic Layer Deposited HfO₂Films on Ge Substrates Depending on Process Temperatures

Abstract

The effect of deposition temperature and post deposition annealing (PDA) on the electrical properties of HfO 2 films grown on a Ge substrate by atomic layer deposition (ALD) was investigated. The HfO 2 films deposited at 280 • C (280 • C-HfO 2 ) showed a large capacitance-voltage (C-V) hysteresis, but it was significantly reduced at 200 • C (200 • C-HfO 2 ). Further reduction of deposition temperature to 160 • C resulted in the abrupt increase of C-V hysteresis. The reduction of C-V hysteresis was originated from the smaller degree of intermixing between the HfO 2 and Ge substrate with decreasing temperature, while the increase of C-V hysteresis comes from the low density of films grown at low temperatures. The C-V hysteresis characteristics were also strongly influenced by PDA temperatures. PDA temperatures higher than 550 • C induced a large C-V hysteresis regardless of deposition temperature. Interestingly, after the PDA process, the HfO 2 grown at 200 • C is crystallized to the tetragonal phase, while the HfO 2 grown at 280 • C is crystallized to the monoclinic phase. These different crystalline phases result in a lower equivalent oxide thickness in the 200 • C-HfO 2 compared to the 280 • C-HfO 2

The Impact of Carbon Concentration on the Crystalline Phase and Dielectric Constant of Atomic Layer Deposited HfO2Films on Ge Substrate

“…[4][5][6][7] Several papers reported that carbon contents in the HfO 2 films on Si substrate increased with decreasing deposition temperature, causing the stabilization of the tetragonal (or cubic) phase. 8,9 However, atomistic mechanism for such stabilization is still under debate. Fischer et al reported that the tendency to stabilize the tetragonal phase is strongly dependent on the kind of dopant used, including Si, C, Ge, Ti, Se, and Ce, and that their ionic size plays a crucial role in the stabilization mechanism.…”

Graded Crystalline HfO₂ Gate Dielectric Layer for High-k/Ge MOS Gate Stack

“…The average ΔVFB of p-HfO2/a-HfO2 and p-HfO2 was 0.28 V and 1.46 V, respectively. Therefore, the additional a-HfO2 layer deposited on p-HfO2 results in the reduction of VFB by ~ 1.18 V, and exhibits lower ΔVFB in comparison with the reported value of a Ge gate stack with a-HfO2 layer [32].…”

“…Although other amorphous high-k films can be applied as a capping layer, it is reported that the interface dipoles at the boundary of different oxide layers can cause additional hysteresis [28,29]. Even compared with the direct diffusion of Ge atoms into the a-HfO2 gate-dielectric, the proposed p-HfO2/a-HfO2 dielectric shows better interface quality [32]. Therefore, the proposed p-HfO2 dielectric capped by a-HfO2 can exhibit improvement of interface quality and reduction of leakage current.…”

Numerical analysis and design of polarization-multiplexing modulator utilizing the epsilon-near-zero behavior in ITO-HfO2-graphene stacked layers

“…Dielectric layer HfO2’s thickness is 2 nm and εHfO2 is 25 31 . Note that εHfO2 is related to the manufacturing process of the film 31 , 43 , 44 . For thickness of 2 nm, the breakdown voltage of HfO2 is 2.6 V. Even if εHfO2 drops to 11 due to the CVD and ALD process, the corresponding voltage in the off state calculated from Equations (3) and (4) do not exceed the breakdown voltage.…”

“…31 Note that ε HfO 2 is related to the manufacturing process of the film. 31,43,44 For thickness of 2 nm, the breakdown voltage of HfO 2 is 2.6 V. Even if ε HfO 2 drops to 11 due to the CVD and ALD process, the corresponding voltage in the off state calculated from Equations ( 3) and ( 4) do not exceed the breakdown voltage. Therefore, the deposition thickness and the ε HfO 2 of the film can be compensated by changing the voltage.…”