Bulletin of the American Physical Society
64th Annual Gaseous Electronics Conference
Volume 56, Number 15
Monday–Friday, November 14–18, 2011; Salt Lake City, Utah
Session ET1: Plasma Deposition |
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Chair: Jeon Han, Sungkyunwkan University Room: 255D |
Tuesday, November 15, 2011 2:00PM - 2:15PM |
ET1.00001: Deposition profile control of carbon films on trenched substrate by simultaneous plasma CVD and plasma etching Masaharu Shiratani, Tatsuya Urakawa, Daisuke Yamashita, Kunihiro Kamataki, Naho Itagaki, Giichiro Uchida, Kazunori Koga, Yuichi Setsuhara, Makoto Sekine, Masaru Hori We have succeeded in realizing subconformal, conformal, and anisotropic deposition profiles of carbon films on trenched substrates by simultaneous plasma CVD and plasma etching. For anisotropic profile, we can deposit carbon films on trenched substrates in three ways, that is, films are deposited on the top without depositing films on the bottom and sidewall, films are deposited on to bottom without depositing films on the top and sidewall, and films are deposited on the top and bottom without depositing films on the sidewall. Such anisotropic deposition profiles can be obtained by tuning the balance between plasma CVD and plasma etching on each surface. Deposition takes place on surface where the deposition rate surpasses the etching rate. The deposition rate depends not only flux of carbon containing radicals but also ion flux, ion energy, and substrate temperature, whereas the etching rate depends not only H flux but also ion flux, ion energy, and substrate temperature. We need precise control of discharge plasmas to tune deposition profile as well as film properties. [Preview Abstract] |
Tuesday, November 15, 2011 2:15PM - 2:30PM |
ET1.00002: Using plasmas to control the nucleation, morphology and properties of self-organized graphene nanosheets Shailesh Kumar, Dong Han Seo, Kostya (Ken) Ostrikov Low temperature non-equilibrium plasma-assisted nanofabrication technique has a great potential for the controllability of nucleation density and complex morphology of various advanced nanomaterials, some of the nanostructures such as vertical vertical graphene nanosheets (GNSSs) can be produced only in a plasma environment. The plasma-assisted control of nucleation and morphology of vertical GNSSs on a catalyst-free substrate have been studied. The plasma-generated electric field was observed to be crucial for the synthesis of self-assembled vertical GNSSs on the undulating surface of the substrate. The process provides the fundamental understanding of the mechanisms for the control over the number density, length and the degree of arrays alignment of the nanosheet by a simple variation of plasma parameters. It was demonstrated the control of degree of graphitization of GNSSs, which enables to tune its electrical resistivity properties from dielectric to semiconducting and metallic, is possible. [Preview Abstract] |
Tuesday, November 15, 2011 2:30PM - 2:45PM |
ET1.00003: Atmospheric pressure cold plasma treatment of cellulose based fillers for wood plastic composites William Lekobou, Karl Englund, Patrick Pedrow, Louis Scudiero The main challenge of wood plastic composites (WPC) resides in the low interfacial adhesion due to incompatibility between the cellulose based filler that has a polar surface and most common matrixes, polyolefins which are non-polar. Plasma treatment is a promising technique for surface modification and its implementation into the processing of WPC would provide this industry with a versatile and nearly environmentally benign manufacturing tool. Our investigation aims at designing a cold atmospheric pressure plasma reactor for coating fillers with a hydrophobic material prior to compounding with the matrix. Deposition was achieved with our reactor that includes an array of high voltage needles, a grounded metal mesh, Ar as carrier gas and C$_{2}$H$_{2}$ as the precursor molecule. Parameters studied have included gas feed rates and applied voltage; FTIR, ESCA, AFM and SEM imaging were used for film diagnostics. We will also report on deposition rate and its dependence on radial and axial position as well as the effects of plasma-polymerized acetylene on the surface free energy of cellulose based substrates. [Preview Abstract] |
Tuesday, November 15, 2011 2:45PM - 3:00PM |
ET1.00004: Behavior of radicals in SiH$_4$/H$_2$ plasma for fabrication of solar cell using silicon thin film Yusuke Abe, Atsushi Fukushima, Ya Lu, Keigo Takeda, Hiroki Kondo, Kenji Ishikawa, Makoto Sekine, Masaru Hori Microcrystalline silicon ($\mu$c-Si:H) thin film grown by low temperature plasma enhanced chemical vapor deposition (PECVD) is an attractive material for applications in thin film solar cells since they can absorb higher wavelength light towards the infrared region of solar spectrum and have excellent stability against light soaking compared to amorphous silicon (a-Si:H) thin films. The flux of hydrogen (H) radicals is a determining factor of crystallinity of thin silicon films in the case of the PECVD. Therefore, it is important to recognize the behavior of H radicals in the plasma. However, the knowledge of H radicals has not been sufficient since it is difficult to measure the H radical absolute density under the actual condition to realize the high deposition rates of $\mu$c-Si:H. In this study, we have constructed a system of measuring the H radical absolute density in the PECVD using vacuum ultraviolet absorption spectroscopy and succeeded in the measurement. The density decreased from $9.1\times10^{12}$ cm$^{-3}$ to $6.0\times10^{12}$ cm$^{-3}$ with increasing SiH$_4$ flow rate. The decreasing is probably due to increasing the reaction of H radical and SiH$_4$. Relation between film quality and radicals will be discussed. [Preview Abstract] |
Tuesday, November 15, 2011 3:00PM - 3:15PM |
ET1.00005: Electrical investigation of the effect of gas additives on silicon deposition plasmas M. Sobolewski, R. Ridgeway, M. Bitner, P. Hurley, D. Sinatore Silane/hydrogen plasmas are used to deposit layers of amorphous and microcrystalline silicon for thin-film solar cells. One way to potentially increase deposition rates and reduce manufacturing costs is to add small amounts of other silicon-containing gases. Such gases, however, may be highly electronegative and may affect the absorption of power by the plasma. Thus, it is difficult to distinguish the chemical effects of each additive from its electrical effects. To investigate such effects, experiments were performed in a capacitively coupled Applied Materials P5000 plasma deposition chamber. Current and voltage probes were mounted on the powered electrode and the stray impedance of the electrode was characterized, allowing accurate determination of the true power absorbed by the discharge. A sheath model was used to distinguish the power absorbed by electrons in the plasma from that absorbed by ions in the sheaths. The power coupling efficiency and the fraction of power absorbed by electrons both fell off sharply at low values of the pressure, power, or electrode gap. For the rest of the experimental conditions, the power coupling and utilization efficiencies were high and nearly constant, indicating that, there, the effect of additives on growth rates is primarily a chemical effect. This work also led to the identification of an electrical signal that indicates growth of the microcrystalline phase. [Preview Abstract] |
Tuesday, November 15, 2011 3:15PM - 3:30PM |
ET1.00006: On Generation and Propagation of the Plasma Ion Beam for Plasma Ion Assisted Deposition (PIAD) of Optical Coatings J. Harhausen, R.P. Brinkmann, R. Foest, A. Ohl, B. Schr\"oder PIAD is a technique employed for the production of high performance optical coatings. Here, the plasma source is a hot cathode direct current discharge with an auxiliary magnetic field (APS). Its specific design together with a low chamber pressure of ${p\sim 2\cdot 10^{-4}\,\mbox{mbar}}$ results in the generation of energetic ions (typ. ${E_i=50..150\,\mbox{eV}}$) impinging onto the substrates. Until today, data on the plasma parameters in the coating chamber is sparse. This contribution presents details on the energy distribution functions (EDF) of electrons and ions in the strongly inhomogeneous APS plume using Langmuir probe and retarding field energy analyzer diagnostics. The IEDF is characterized by two separate populations of low and high energy. An analytical model for the evolution of the ion beam reveals that the slow ion component is due to charge exchange of fast ions with the background neutral gas. This model is indispensable for the estimation of the NEDF. [Preview Abstract] |
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