Kon-Tsu Kin

Low-temperature method for enhancing sputter-deposited HfO2 films with complete oxidization

A low-temperature method, supercritical CO2 fluid (SCF) technology, is proposed to improve the dielectric properties of ultrathin hafnium oxide (HfO2) film at 150°C without significant formation of parasitic oxide at the interface between HfO2 and Si substrate. In this research, the HfO2 films were deposited by dc sputter at room temperature and post-treated by SCF which is mixed with 5vol% propyl alcohol and 5vol% H2O. From high-resolution transmission electron microscopy image, the interfacial oxide of SCF-treated HfO2 film is only 5A thick. Additionally, the enhancements in the qualities of sputter-deposited HfO2 film after SCF process are exhibited by x-ray photoelectron spectroscopy and capacitance-voltage (C-V) measurement.

A low temperature fabrication of HfO2 films with supercritical CO2 fluid treatment

To improve the dielectric properties of sputter-deposited hafnium oxide (HfO2) films, the supercritical CO2 (SCCO2) fluid technology is introduced as a low temperature treatment. The ultrathin HfO2 films were deposited on p-type (100) silicon wafer by dc sputtering at room temperature and subsequently treated with SCCO2 fluids at 150°C to diminish the traps in the HfO2 films. After SCCO2 treatment, the interfacial parasitic oxide between the Si substrate and HfO2 layer is only about 5A, and the oxygen content of the HfO2 films apparently increased. From current-voltage (I-V) and capacitance-voltage (C-V) measurements, the leakage current density of the SCCO2-treated HfO2 films is repressed from 10−2to10−7A∕cm2 at electric field=3MV∕cm due to the reduction of traps in the HfO2 films. The equivalent oxide thickness also obviously decreased. Besides, the efficiency of terminating traps is relative to the pressure of the SCCO2 fluids.

Effects of Supercritical Fluids Activation on Carbon Nanotube Field Emitters

This paper proposes a novel method to enhance the emission characteristics of carbon nanotubes (CNTs). It is extremely possible for CNTs to adsorb moisture and other contaminants during the fabrication processes, leading to the degraded field emission characteristics. In this work, CNT emitters are activated with commonly used heating process and supercritical carbon dioxide (SCCO2) fluids technology for removing adsorbed residue moisture. Experimental results have demonstrated that the electrical stability and field emission enhancement of CNT emitters are effectively achieved by the SCCO2 fluids treatment compared to the heating process, due to the minimization of residuary moisture in CNTs

Activation of Carbon Nanotube Emitters by Using Supercritical Carbon Dioxide Fluids with Propyl Alcohol

Carbon nanotubes CNTs as electric field emitters have especially received great attention, due to their high mechanical strength and chemical stability coupled with very high aspect ratios, leading to extremely strong local fields. 1-3 These attractive properties of CNTs make them extraordinary materials for field emission display FED applications. 4 For most electrical applications, the nanotubes need to be produced free of impurities, contamination, and minimized moisture adsorption. The two major sources of contamination in the growth of CNTs, including amorphous carbon and extraneous metal catalyst, can be eliminated by the cautious use of etching gases and by optimizing the catalyst formula, respectively. 5,6 However, few studies have been reported for the efficient drying methods to minimize residual moisture in the nanostructure CNTs. In general, a trace of residual moisture in electronic devices tends to degrade electrical performance and cause electrical instability. As for the field emission characteristics of CNTs, experimental work really focused on the study of the moisture adsoption effect also has been lacking so far. Therefore, in this work the influence of residual moisture on the field emission of CNTs is investigated first. In addition, the application of supercritical carbon dioxide SCCO2 fluids is proposed to activate CNT emitters, minimizing residual moisture uptake with no possible damage to the CNTs. The CO2-based processing is attractive because of its environmental compatibility, as it is nontoxic, nonflammable, and unreactive under most conditions. 7 SCCO2 is similar to liquid CO2 since it also dissolves methanol. Additionally, it possesses gas-like properties of diffusivity and viscosity that allow it to remove solvents from the narrow spaces between micro- and nanotructure surfaces. 8 Also, the extremely low surface tension of SCCO2 can account for its negligible effect i.e., extremely low damage on the morphology and microstructures. 9-11

Application of Supercritical CO2 Fluid for Dielectric Improvement of SiO x Film

Institute of Electronics Engineering, National Tsing Hua University, HsinChu 300, Taiwan Department of Physics and Institute of Electro-Optical Engineering, Center for Nanoscience and Nanotechnology, National Sun Yat-sen University, Kaohsiung 804, Taiwan Department of Photonics and Display Institute, National Chiao Tung University, HsinChu 300, Taiwan Industrial Technology Research Institute, Energy and Environment Research Laboratories, HsinChu 300, Taiwan

Programming Efficiency of Stacked-Gate Flash Memories with High-κ Dielectrics

The programming efficiency of high-permittivity (κ) inter-poly dielectrics (IPDs) and tunnel dielectrics (TDs) on the stacked-gate flash memory performance is evaluated. By 2D MEDICI simulation, stacked-gate flash memories with high-κ IPDs clearly exhibited significant improvement in operation speed over those with conventional oxide/nitride/oxide IPD programmed with either channel Fowler-Nordheim (CFN) or channel hot electron (CHE) injection. Choosing HfO2as the IPD and using CFN programming scheme, the operating voltage can be reduced by more than 48% under a typical 10μs programming time. However, the effect of high-κ TDs was quite different when compared with high-κ IPDs. High-κ TDs were only beneficial for memories programmed with CHE injection instead of CFN tunneling. The operating voltage can be reduced by more than 27% under 10μs programming time by choosing HfO2as both the IPD and TD with CHE programming scheme. Due to the contrary improvement in programming schemes, high-κ IPDs and TDs were suitable for next-generation NAND- and NOR-type stacked-gate flash memories, respectively.

Characterization of Inter-Poly High-κ Dielectrics for Next Generation Stacked-Gate Flash Memories

In this paper, the inter-poly dielectric (IPD) thickness, scaling, and reliability characteristics of Al2O3and HfO2IPDs are studied, which are then compared with TEOS IPD. Regardless of deposition tools, drastically leakage current reduction and reliability improvements have been demonstrated by replacing TEOS IPD with high-permittivity (high-κ) IPDs, which are suitable for mass production applications in the future. Moreover, MOCVD deposition can be used to further promote dielectric reliability when compared to reactive-sputtering deposition. By using MOCVD deposition, the QBDcan be significantly improved, in addition to reduced leakage current density, enhanced breakdown voltage and effective breakdown field. Our results clearly demonstrate that both MOCVD-Al2O3and MOCVD-HfO2IPD possess great potential for next generation stacked-gate flash memories.