Improved electrical properties of Pt/HfO2/Ge using in situ water vapor treatment and atomic layer deposition

Abstract

The effects of water vapor treatment (WVT) on a Ge substrate were investigated in order to understand the improved electrical properties of Pt/HfO2/Ge metal-oxide-semiconductor (MOS) capacitors. The WVT and HfO2 deposition were performed in situ using an atomic layer deposition technique to avoid air exposure. As a result, the WVT on cleaned Ge substrates reduced the native oxide effectively and enhanced the initial growth of the HfO2 film. The improved interface qualities with WVT enhanced Ge-based device performance through a smoother capacitance-voltage curve, less increase in the inversion capacitance, and lower density of interface states.

Annealing induced hysteresis suppression for TiN/HfO2/GeON/p-Ge capacitor

“…For the annealed sample, the calculated surface potential variation from accumulation to strong inversion using the Berglund method [12] is about 0.7 V, indicating that the Fermi level (E f ) can sweep through the whole band gap and is not pinned, which is important to achieve good performance for Ge devices, especially on the p-type Ge substrate. [2,13] For a MOSCAP with high-κ dielectric, hysteresis is a big problem to be solved [3,4,[8][9][10]. To investigate the hysteresis, the gate voltage was swept from −1.5 to 1.5 or 2.0 V. As can be seen in figure 3(a), for the as-deposited sample the bigger the positive voltage, the larger the observed hysteresis is when the gate voltage is swept back to −1.5 V. This phenomenon is attributed to the large amount of electron traps existing in the dielectric layer.…”

“…Effective passivation of the interface traps of Ge-MOSCAP, especially for the p-type Ge substrate, is vital to Ge-based MOSFETs [2]. Fortunately, some effective methods to passivate the Ge interface were recently reported, such as the introduction of GeO 2 [3,4], GeON [5,6], and rare earth oxides [7] as the interfacial layer between Ge substrate and high-κ layer or a post-process by water vapor [8]. When integrating high-κ oxides into a MOSCAP, capacitance-voltage (C-V) hysteresis is an important issue to be solved [8][9][10].…”

“…Fortunately, some effective methods to passivate the Ge interface were recently reported, such as the introduction of GeO 2 [3,4], GeON [5,6], and rare earth oxides [7] as the interfacial layer between Ge substrate and high-κ layer or a post-process by water vapor [8]. When integrating high-κ oxides into a MOSCAP, capacitance-voltage (C-V) hysteresis is an important issue to be solved [8][9][10]. To both suppress the hysteresis and reserve the excellent passivation property of the GeON interlayer, an appropriate process is required.…”

Asymmetric Current Behavior on Unipolar Resistive Switching in Pt/HfO2/Pt Resistor With Symmetric Electrodes

“…I N THE sub-100 nm era in semiconductor devices, HfO 2 films have been widely used as dielectrics in metal-oxide-semiconductor and metal-insulator-metal (MIM) capacitors due to their high permittivity, medium bandgap, high reliability, and thermal stability [1], [2]. Besides applications in capacitors, in recent years, the resistive switching (RS) phenomena between the low resistance state (LRS) and the high resistance state (HRS) of a HfO 2 insulator sandwiched between metal electrodes have been intensively investigated [3]- [11].…”