Kung Ming Fan

Fluorine effects on the dipole structures of the Al2O3 thin films and characterization by spectroscopic ellipsometry

Fluorine-terminated chemical bonds and dipole structures within an Al2O3 layer were investigated in this study. Spectroscopic ellipsometry (SE) was employed to estimate the characteristics of fluorinated Al2O3. The parameters S0 and λ0 extracted from SE were analyzed to detect the influence of F-terminated bonding. Al–O bonds were replaced by the Al–F bonds after fluorine was implanted on the silicon substrate. A physical model of dipole structures was proposed explaining the F incorporation phenomenon.

Improvements on Interface Reliability and Capacitance Dispersion of Fluorinated ALD- Al2O3 Gate Dielectrics by CF4 Plasma Treatment

The characteristics of atomic layer deposited (ALD)-Al 2 O 3 gate dielectrics with CF 4 plasma surface treatment have been studied in this paper. Fluorine atoms were observed to be incorporated at bulk Al 2 O 3 and pile-up at both Al/Al 2 O 3 and Al 2 O 3 /Si interfaces. X-ray photoelectron spectroscopy analysis demonstrated that Al-O bonds were replaced by Al-F and F-Al-O bonds as samples were treated in CF 4 plasma. A physical model was proposed to explain the capacitance-equivalent-thickness (CET) degradation and capacitance-frequency-dispersion phenomenon. The CF 4 plasma-treatment approach can immunize capacitance dispersion due to its excellent capability of interface trap passivation by fluorine atoms in Al 2 O 3 dielectrics. Fluorine incorporation was proven to improve the Al 2 O 3 dielectric characteristics of hysteresis, oxide reliability, and capacitance dispersion.

Effects of Post CF4 Plasma Treatment on the HfO2 Thin Film

In this study, a novel approach was proposed to improve the characterization of HfO2. Fluorine was incorporated by CF4 plasma to improve the HfO2 gate dielectric properties including leakage current, breakdown voltage and hysteresis. The hysteresis of capacitance–voltage characteristics can be reduced to approximately 10% hysteresis voltage for the samples with CF4 plasma treatment. An inner-interface trapping model is presented to explain the hysteresis. The secondary-ion mass spectroscopy (SIMS) results show that there is a significant incorporation of fluorine (F) at the interface between the HfO2 thin film and silicon substrate. The incorporation of F effectively suppressed leakage current and improved carrier trapping without an increase in interfacial layer thickness.

Characterizations of HfxMoyNz Alloys as Gate Electrodes for n-and p-Channel Metal Oxide Semiconductor Field Effect Transistors

In this article, the work functions (Φm) of hafnium–molybdenum (HfxMoy) alloys were modified using nitrogen in dc reactive cosputtering for the first time. The HfxMoyNz alloys show low resistivity and excellent thermal stability up to 900 °C. In addition, the work functions (Φm) of the HfxMoyNz alloys were tuned from the conduction band (4.17 eV) to the valence band (5.16 eV) by increasing the nitrogen flow ratio. From the X-ray diffraction (XRD) data, the MoN(200) peak can be observed for samples with a nitrogen ratio higher than 6%, which was responsible for the work function (Φm) increase in the HfxMoyNz alloys.

Reoxidation after NH3 Plasma Nitridation for Multiple-Thickness Oxynitrides

A novel manufacturable multiple gate oxynitride thickness technology is proposed in this work. An ultrathin dielectric film (EOT=2.5 nm) of lower oxidation growth rate than conventional films was fabricated by NH3 plasma nitridation. Oxide thickness was reduced by about 80% for samples treated by NH3 plasma nitridation. However, the thickness limitation is 1.3 nm for NH3 plasma nitridation. This is believed to be due to nitrogen incorporated in the silicon surface to form a nitridelike thin film, which retarded oxide growth. The effects of NH3 plasma nitridation were systematically studied, and the rapid thermal N2O reoxidation of an NH3 plasma sample was also demonstrated in this work. This novel process improves the gate oxide reliability, decreases bulk trap densities, provides better SILC immunity, and produces less charge trapping and a higher Qbd.

Programming Speed Enhancement by NH3 Plasma Nitridation of Tunneling Oxide for Ge Nanocrystals Memory

The characteristics of Ge nanocrystals charge-storage memory stacks with NH 3 plasma surface treatment of the tunneling oxide layer have been studied in this paper. The tunneling silicon oxide (TO) surface was nitrided by NH 3 plasma treatment, which appears to modify the bonding type of the substrate surface and enhance the nucleation sites for Ge nanocrystals. The chemical bonding depth profile of the Si x Ge 1-x /TO layers and the Ge nanocrystals structure were examined by X-ray photoelectron spectroscopy and transmission electron microscopy, respectively. The trap charge densities were estimated to be as high as 9.1 X 10 12 cm -2 from hysteresis loop for ± 10 V sweep. The nitrided interface (oxynitride) between the trapping layer and the tunneling silicon oxide has a bandgap lower than the silicon oxide, which causes an asymmetric tunneling barrier under programming and erasing conditions. An effective thinner barrier under programming bias results in enhanced programming speed due to improved carrier injection efficiency. It was also observed that the nitrided interface reduces Ge diffusion into the TO layer, which is known to result in degradation of the properties of Ge nanocrystal-based memory devices.

Improvement of Charge Programming and Retention by NH 3 Plasma Treatment on Tunnel Oxide for SiO 2 /Si x Ge 1-x /SiO 2 Tri-layer Memory Devices

The aim of this paper is to study, the NH₃ plasma technique to improve the charge programming speed and retention time for the SiO₂/Si_xGe_1-x/SiO₂ tri-layer memory devices. The modulated tunnel oxide energy band gap near Si_xGe_1-x/TO interface is suitable for enhancing the programming and charge retention performance.

Fluorinated ALD Al/sub 2/O/sub 3/ Gate Dielectrics by CF/sub 4/ Plasma

Introduction As device scaling down, the silicon oxide thickness is shrinking to nanometer scale. High-k dielectric is necessary to avoid high gate leakage current and enhance drive ability. Al2O3 is a candidate dielectric for DRAM or CMOS technology because of its high thermal stability and energy band gap [1, 2]. However, some fixed charges are located in the Al2O3 films and affects the flatband voltage (Vfb) shift. CF4 plasma had been used in the HfO2 gate dielectric to improve hysteresis [3]. In this study, a novel approach for fluorinated ALD-Al2O3 films by the CF4 plasma was proposed. Due to fluorine incorporation, the characterization was improved including breakdown field, hysteresis and reliability. Experiment Rapid thermal nitridation (RTN) was processed on p-Si followed by atomic layer deposition (ALD)-Al2O3 with precursor of Trimethylaluminum (TMA) and O3. ALD processes were split to 40, 69 and 109 cycles. CF4 plasma was treated on the Al2O3 for 1, 3 and 5 min. Aluminum gate electrode was deposited and patterned. The key processes for (a) without CF4 plasma and (b) with CF4 plasma are shown in the Fig. 1. Electrical characteristics were measured with gate areas of 80μm*80μm. Results and Discussion

Effects of Post CF4Plasma Treatment on the HfO2Thin Film

In this study, a novel approach was proposed to improve the characterization of HfO2. Fluorine was incorporated by CF4 plasma to improve the HfO2 gate dielectric properties including leakage current, breakdown voltage and hysteresis. The hysteresis of capacitance–voltage characteristics can be reduced to approximately 10% hysteresis voltage for the samples with CF4 plasma treatment. An inner-interface trapping model is presented to explain the hysteresis. The secondary-ion mass spectroscopy (SIMS) results show that there is a significant incorporation of fluorine (F) at the interface between the HfO2 thin film and silicon substrate. The incorporation of F effectively suppressed leakage current and improved carrier trapping without an increase in interfacial layer thickness.