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Journal ArticleDOI

Determination of the possible magnitude of the charging effect in a SCALPEL mask membrane

02 Dec 1999-Journal of Vacuum Science & Technology B (American Vacuum Society)-Vol. 17, Iss: 6, pp 2888-2892

AbstractPreviously, we theoretically investigated the charging of free standing dielectric thin films irradiated by 100 keV electrons and formulated kinetic equations describing the dynamic process [M. Mkrtchyan et al., Microelectron. Eng. 46, 233 (1999)]. It was shown that in the currently used SCALPEL® masks comprising a 1000-A-thick amorphous SiNx film supported by a grillage of Si struts, the membrane charging could be significant and might have an adverse effect on the system performance. The membrane charging, sensitive to both the conductivity and the geometry of conductive path, can be regulated in a straightforward manner by tailoring both of them; for instance, by applying a top surface conductive layer (TSCL) with an appropriate thickness and doping level. Here we discuss the results obtained on the basis of our charging model modified to be applicable to the case of a SiNx membrane with a TSCL (e.g., a 10-nm-thick amorphous Si or poly-Si film doped by boron). The results presented demonstrate that thi...

Topics: Amorphous solid (53%)

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Journal ArticleDOI
Abstract: We report a method for fabrication of continuous, conformal, ultrathin (i.e., 15–30 nm) Cu films using a room temperature, aqueous-based, electroless deposition technique on silica and polymer planarizer surfaces. The Cu films are sufficiently homogeneous, electrically conductive, and optically transparent for use as resist discharge layers during e-beam patterning of the substrate. The grounded Cu film, deployed here as a resist underlayer, eliminates the 0.1–0.4 μm subfield stitching errors normally observed in the absence of the Cu film during resist patterning on a glass or insulating substrate. The Cu is readily removed using a nitric acid wet etch following patterning.

26 citations


Journal ArticleDOI
Abstract: In this article, we describe the analysis procedures of charging effects and calculation results of surface potential and beam deflection in electron beam lithography. Monte Carlo simulation is performed to obtain the charge distribution in e beam resist. A focused (Gaussian) and a flood beam are considered for beam shapes of the exposure system. The effects of discharging due to electron beam induced conductivity are included in the analysis. The Poisson equation is solved for the potential distribution by using the simultaneous overrelaxation method. The iteration technique is used for the convergence of the potential. With the given potential distribution, beam deflection is calculated using the fourth order Runge–Kutta integration algorithm. Comparison of the values of the surface potential obtained by simulations with experimental results by Pease' group at Stanford University show similar shapes between them. We also have applied this work to a SCALPEL mask with a thin silicon nitride membrane. This...

12 citations


Journal ArticleDOI
Abstract: Electron inelastic scattering in thin films is briefly discussed. It is found that in thin films of interest the plasmon generation by an energetic electron is the dominant process and the electron energy loss spectra (EELS) can be described by an analytical function of the membrane thickness and the material characteristics. A straightforward procedure using the analytical approximation of EELS and the results obtained from it for the SCALPEL mask-membrane in terms of chromatic aberration evaluation and control are presented.

2 citations


References
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Journal ArticleDOI
Abstract: Hall‐mobility measurements have been performed on polycrystalline silicon films deposited on a silicon oxide surface by the thermal decomposition of silane. Samples with doping impurities added during deposition or by diffusion from a doped vapor‐deposited oxide showed similar behavior. For both n‐type and p‐type samples approximately 5 μ thick, the mobility reached a maximum value of about 40 cm2/V sec at a free carrier concentration of about 1018 cm−3 and decreased for both higher and lower carrier concentrations. The observed Hall mobility was generally higher in p‐type samples than in n‐type samples. The decrease in observed mobility with decreasing carrier concentration is attributed to the effects of high resistivity space‐charge regions surrounding grain boundaries in the polycrystalline material. The mobility was seen to increase as the film thickness increased for samples with similar doping, indicating a more ordered structure in thicker films.

403 citations


Journal ArticleDOI
Abstract: Hall mobility and conductivity measurements have been made as a function of temperature on a series of n- and p-type a—Si specimens prepared by the glow discharge technique and doped with phosphorus or boron atoms. The Hall effect exhibits an interesting double reversal in sign : n-type samples show a Hall potential in the direction normally expected for holes and the opposite applies to p-type specimens. In lightly doped n-type samples, the observed Hall mobility μmH has a magnitude of about 0.1 cm2V−1see−1, essentially independent of temperature; this is in agreement with theoretical predictions for transport in the extended states. On increasing the donor density, μmH begins to show a temperature dependence which varies systematically with the doping level. The conductivity and Hall data for n-type specimens have been analysed in terms of a model with two parallel conduction paths, one in the extended electron states and the other through the localized impurity levels where transport takes pla...

147 citations


Journal ArticleDOI
Abstract: Origin of memory traps in chemically vapor‐deposited silicon nitride films was investigated. Electron‐spin resonance and infrared absorption measurements revealed the existence of silicon dangling bonds which have three‐folded configuration. Correlation between the spin density and the metal‐nitride‐oxide‐semiconductor (MNOS) memory characteristics was studied, and it was suggested that silicon dangling bonds are responsible for the trap states which cause not only hopping conduction, but also memory behavior. A model is presented suggesting that the dangling bonds are positively, neutrally, or negatively ionized. The MNOS memory behavior and the energy level of the traps were well interpreted by taking into account the transition of the dangling bonds.

113 citations


Journal ArticleDOI
Abstract: Charging of the workpiece in electron beam lithography is well recognized as a source of pattern placement error. Despite considerable previous effort there is little quantitative understanding of the problem. A new technique was recently reported in which the surface potential of a resist film during and after exposure was measured directly. Here we describe results obtained using an improved version of the technique for charging of resists under a wide variety of conditions. Some results are as expected, e.g., thicker resists tended to charge more negatively than did thinner ones. Other results are surprising; for example, under certain conditions (7 keV, 0.4 μm polybutene sulfone) there was zero potential at the surface and at higher energies (10 keV) the surface charged positively (0.7 V). The detailed mechanism for positive charging under these conditions is still unclear.

56 citations


Journal ArticleDOI
Abstract: Electron scattering in thin solid films used for the fabrication of masks for electron projection lithography, e.g., SCALPEL®, is investigated. We have developed an analytical model to calculate electron transmission through the mask membrane and image contrast due to different scattering properties of the patterned area and the membrane. The model utilizes cross sections for electron elastic and inelastic scattering on an atom with exponentially screened Coulomb potential of the nucleus derived in the first Born approximation. The variety and controversy of theoretical and empirical adjustments of the screening parameter are briefly analyzed and attributed to the misinterpretation of experimental data ignoring the effects mostly due to plural scattering of electrons and dense packing of atoms in thin solid films. This model frees us from the computational limitations of Monte Carlo simulations and proves to be effective for the straightforward characterization of various alternative materials for SCALPEL...

24 citations