Sungho Heo

Reproducible hysteresis and resistive switching in metal-CuxO-metal heterostructures

Materials showing reversible resistance switching between high-resistance state and low-resistance state at room temperature are attractive for today’s semiconductor technology. In this letter, the reproducible hysteresis and resistive switching characteristics of metal-CuxO-metal (M-CuxO-M) heterostructures driven by low voltages are demonstrated. The fabrication of the M-CuxO-M heterostructures is fully compatible with the standard complementary metal-oxide semiconductor process. The hysteresis and resistive switching behavior are discussed. The good retention characteristics are exhibited in the M-CuxO-M heterostructures by the accurate controlling of the preparation parameters.

Improvement of reproducible hysteresis and resistive switching in metal-La0.7Ca0.3MnO3-metal heterostructures by oxygen annealing

Materials showing reversible resistance switching between high-resistance state and low-resistance state at room temperature are attractive for today’s semiconductor technology. In this letter, the improvement of reproducible hysteresis and resistive switching characteristics of metal-La0.7Ca0.3MnO3-metal (M-LCMO-M) heterostructures is demonstrated. The fabrication of the M-LCMO-M heterostructures is compatible with the standard complementary metal-oxide semiconductor process. The effect of oxygen annealing on the improvement of the hysteresis and resistive switching is discussed. The good retention characteristics are exhibited in the M-LCMO-M heterostructures by the accurate controlling of the preparation parameters.

Sub-15 nm n+/p-germanium shallow junction formed by PH3 plasma doping and excimer laser annealing

An n + /p germanium (Ge) ultrashallow junction formed by PH 3 plasma doping (PLAD) and KrF excimer laser annealing is demonstrated. In order to improve the n-type dopant activation without significant diffusion in the n + /p-Ge junction, we applied laser annealing on the PLAD samples. Compared with rapid thermal annealing (RTA), the laser annealing yielded shallower junction depth (∼15 nm) with low sheet resistance and comparable leakage current characteristics in the Ge n + /p junction. Therefore, PLAD with laser annealing can be considered as an alternative method for fabricating future Ge metal-oxide-semiconductor field-effect-transistors.

Characteristics of HfO/sub 2/ pMOSFET prepared by B/sub 2/H/sub 6/ plasma doping and KrF excimer laser annealing

The electrical characteristics of HfO/sub 2/ pMOSFETs prepared by B/sub 2/H/sub 6/ plasma doping and excimer laser annealing were investigated. Various metal gate electrodes were evaluated to protect the high-/spl kappa/ oxide during laser irradiation. Although the aluminum gate electrode showed superior reflectivity to the laser, the equivalent oxide thickness was increased due to the interaction between aluminum and HfO/sub 2/, which resulted in reduced capacitance. In contrast, the Al-TaN stacked gate showed good reflectivity up to laser energy of 500 mJ/cm/sup 2/ and improved capacitance was obtained compared with the Al gate. For the first time, the electrical characteristics of a HfO/sub 2/ pMOSFET with an Al-TaN gate fabricated by plasma doping and excimer laser annealing were demonstrated. It was also demonstrated that plasma doping and excimer laser annealing combined with a metal gate could be applied for high-/spl kappa/ oxide MOSFET fabrication.

Electrical Characteristics of LaAlO3 Gate Dielectrics Prepared by High-Pressure Hydrogen Post-Deposition Annealing

To improve electrical characteristics of high-k gate dielectrics, post-deposition annealing (PDA) was performed in high-pressure (10 atm) pure hydrogen ambient. High-pressure PDA samples show excellent electrical characteristics such as low fixed charge density, and reduced interface state density confirmed by capacitance-voltage analysis and conductance technique, respectively. They also showed no frequency dependency and a hysteresis of 2.9 mV. The leakage current decreases remarkably from 0.23 to 2.44 X 10 -7 Ampere/cm 2 at the gate voltage of 1 V below V FB . The excellent electrical characteristics of high-pressure hydrogen annealed sample can be explained by enhanced hydrogen passivation of defects in high-k dielectric.

Ultrashallow (<10nm) p+∕n junction formed by B18H22 cluster ion implantation and excimer laser annealing

In order to form an ultrashallow p+∕n junction, incorporation of a top amorphous-silicon (a-Si) layer is necessary so as to avoid channeling and to fully activate the dopant. Conventional ultrashallow junction processes require two-step implantation such as preamorphization by Si+ or Ge+ implantation and ultralow (<0.5keV) energy B+ implantation. In this report, the authors investigate B18H22+ implantation. Due to the heavy mass of cluster ions, one-step ion implantation at 5keV readily forms a 5-nm-thick a-Si layer and an ultrashallow junction without B channeling. By employing excimer laser annealing, the authors have obtained a shallow junction depth (∼9nm) and low Rs (∼830Ω∕◻).

Characteristics of heavily doped p+/n ultrashallow junction prepared by plasma doping and laser annealing

High quality p+∕n ultrashallow junctions were fabricated by high dose plasma doping and two step annealing involving low-temperature furnace annealing and excimer laser annealing. Without a preamorphization process, laser annealing is effective in terms of activation and annealing. Meanwhile, the junction depth can be controlled by the low-temperature annealing process prior to the laser annealing. By combining low-temperature preannealing and laser annealing, ultrashallow (junction depth ∼22nm), low sheet resistance (∼275Ω∕sq.), and a defect-free p+∕n junction can be obtained without preamorphization.

Characteristics of Al2O3 gate dielectrics partially fluorinated by a low energy fluorine beam

The partial fluorination of Al2O3 gate dielectrics was examined by exposing an oxide-nitride-aluminum oxide (ONA) stack to a low energy fluorine beam, and its effect on the properties of the ONA was investigated. Exposing ONA to about 10 eV fluorine beam resulted in a 5-nm-thick AlOxFy layer on the ONA by replacing some Al–O to Al–F. The electrical properties such as leakage current and memory window characteristics were improved after fluorination of the ONA, possibly due to the improved charge trapping characteristics through the formation of an AlOxFy layer on the Al2O3 without changing the blocking layer thickness.

Characteristics of ultrashallow p + /n junction prepared cluster boron (B 18 H 22 ) ion implantation and excimer laser annealing

Ultrashallow junction (<10 nm) p⁺/n junction formed by B₁₈H₂₂ cluster ion implantation and excimer laser annealing (ELA) is demonstrated. B₁₈H₂₂ ⁺ equivalent implantation energy at 0.25 keV readily forms an amorphous-silicon (a-Si) layer without additional Si⁺ or Ge⁺ implantation. After ELA at 500 mJ/cm², diffusion of the boron profile was almost negligible, which can be explained by selective melting of a-Si

Ultra-shallow Junction Formed by Plasma Doping and Laser Annealing

We investigated ultra-shallow junction prepared by plasma doping (PLAD) and laser annealing (LA). Although PLAD is promising doping technology for the sub-45nm technology node due to the high dose rate at low energy, it has problems which is related with hydrogen or fluorine. The implanted hydrogen generally increases damage in the Si substrate. The fluorine also retards dopant activation and increases dopant deactivation during post-annealing step. Conventional one step annealing processes such as rapid thermal annealing (RTA) or excimer laser annealing (LA) are not effective method for high dopant activation. To minimize the effect of hydrogen or fluorine, we propose additional pre-annealing followed by conventional laser annealing. By employing low temperature pre-annealing, we can improve electrical characteristics such as low sheet resistance, high activation rates, shallow junction depth and reduced dopant deactivation. The improvement can be explained by reduced defect density and out-diffusion of fluorine or hydrogen which in turn enhances dopant activation during ELA