摘要:

We have developed a nanofabrication method that uses patterned anodic silicon oxide as a template for pattern transfer to a gold (Au) nanostructure. The oxide patterns were prepared on a hydrogen‐terminated silicon (Si–H) surface by scanning probe anodization, that is, electrochemical nanolithography based on scanning probe microscopy. These anodic oxide patterns were transferred to Au patterns through area‐selective electroless plating, in which Au deposition proceeds selectively on the unanodized Si–H area while the anodic oxide surface remains free of deposits. Due to low Au nucleation density on the Si–H surfaces, Au lines formed by the electroless plating were discontinuous when their linewidth narrowed to less than 50 nm. The nucleation density was increased by a chemical etching of the Si–H surface prior to plating. We have successfully fabricated a continuous Au line as narrow as ∼30 nm.

ISSN:0734-211X    

DOI:10.1116/1.588111

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

An atomic force microscope (AFM) was used to study the microwear process of polycarbonate (PC). Testing included line scratching of the polymer surface using a microfabricated Si3N4AFM tip of 10–20 nm radius. Interfacial adhesion, friction, the effect of the number of scratches, and scanning speed were studied. Unlike previous reports, projections as a result of polycarbonate apparent volume increase have been observed after reciprocal scratching on the same track (without an AFM tip lateral feed). In spite of analytically predicted elastic/plastic contact, no plastic deformation was found during the tests. A model, based on the formation of cracks and their growth was suggested to explain these phenomena. No viscoelastic/plastic behavior (scanning speed effect on friction or microwear) was found.

ISSN:0734-211X    

DOI:10.1116/1.588112

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

A summary is given of an experimental method used to obtain the local dielectric strength of thin insulators using atomic force microscopy with conducting tips. This technique is applied to 7–15 nm thick SiO2films grown on either crystalline silicon or polysilicon substrates. The dielectric breakdown of the oxides over small areas (∼5×10−16m2) follows that observed in the intrinsic breakdown of conventional metal–oxide–semiconductor structures, with a maximum breakdown field of 13.2±0.8 MV/cm. On the polycrystalline samples variation in dielectric strength between individual grains can be observed, with the oxide over some grains breaking down entirely. A difficulty when working in air is that sample or tip contamination and induced growth of material under the tip lead to changes in either the effective barrier height or local material thickness which are not related to the SiO2film. These effects are discussed in detail.

ISSN:0734-211X    

DOI:10.1116/1.588113

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

We present a method for measuring molecular‐beam epitaxy growth rates in near real‐time on rotating substrates. This is done by digitizing a video image of the reflection high‐energy electron diffraction screen, automatically tracking and measuring the specular spot width, and using numerical techniques to filter the resulting signal. The digitization and image and signal processing take approximately 0.4 s to accomplish, so this technique offers the molecular‐beam epitaxy grower the ability to actively adjust growth times in order to deposit a desired layer thickness. The measurement has a demonstrated precision of approximately 2%, which is sufficient to allow active control of epilayer thickness by counting monolayers as they are deposited. When postgrowth techniques, such as frequency domain analysis, are also used, the reflection high‐energy electron diffraction measurement of layer thickness on rotating substrates improves to a precision of better than 1%. Since all of the components in the system described are commercially available, duplication is straightforward.

ISSN:0734-211X    

DOI:10.1116/1.588114

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

This article presents the investigative results of pulsed threshold current densities of niobium tip cathodes at temperatures ranging from 4.2 to 300 K. It has been shown that the superconducting‐to‐normal phase state transition of the cathode has no effect on pulsed threshold current densities. Estimations have been made for the factors limiting the current from a superconducting emitter. The experiments have shown that the cooling of the cathode from 300 to 4.2 K changes the dynamics of cathode heating considerably and leads to a steady increase in the threshold current densities with the delay time range of 10−9–10−6s. Numerical analysis of thermal processes in the emitter has shown that the above effects are not due to the difference between the electron and the phonon temperatures (the electron–phonon relaxation time does not exceed 10−9s), but to the more intense heat transfer processes and the reduction of Joule heating, with the cooling of the cathode. It has been shown that the space charge of emitted electrons produces a considerable effect on the temperature and current density distribution in the tip apex. Investigations have shown that the mechanism of the tip cathode failure depends on the delay time range. The simple relationship for estimation of average pulsed threshold emission current density of the tip cathode for a delay time range of 10−9–10−7s is presented.

ISSN:0734-211X    

DOI:10.1116/1.588115

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Double‐gated Si field emitter arrays (FEAs) capable of generating focused electron beams were fabricated and experimentally evaluated. The present field emitter array has a vertical triode structure consisting of a conical Si tip and two gate openings (upper and lower) surrounding the tip. The lower gate with a 2‐μm‐diam opening acts as an extraction electrode controlling the emission current, and the upper one with a 3‐μm‐diam opening acts as an electrostatic lens focusing the electron trajectories. The focusing property was evaluated by observing the spot size of a phosphor (ZnO:Zn) screen located about 20 mm apart from the field emitter array and biased to 1 kV. It was found from experimental results that decreasing the upper gate voltage (VF) down to a few volts was quite effective to generate focused electron beams. AtVFof about 4 V, the electrons emitted from the tip were well collimated and a beam current of about 0.1 nA/tip was obtained.

ISSN:0734-211X    

DOI:10.1116/1.588116

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

We have fabricated uniform arrays of 120‐nm‐diam dot masks on 300 nm centers using laser interference lithography. Chrome, cobalt, nickel, and germanium dot arrays have been fabricated. The density of these arrays is ≳109dots/cm2. The standard deviation of the average dot diameter is 7.4% over a 5‐cm‐diam silicon substrate. The center‐to‐center spacing of the dot mask is determined by the laser wavelength and interference angle. Some control over the dot diameter is possible by varying the angle of the substrate during the metal deposition prior to liftoff. We have used a reactive ion etch with these metal dot masks to form single crystal silicon pedestals demonstrating that these structures are suitable for self‐aligned gated field emitter array fabrication.

ISSN:0734-211X    

DOI:10.1116/1.588117

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

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.

ISSN:0734-211X    

DOI:10.1116/1.588118

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

A focused electron beam was found, in the presence of oxygen gas, to induce the etching of a plasma enhanced chemical vapor deposited amorphous hydrogenated carbon (PECVDa‐C:H) film. This reaction was used to pattern the film directly, eliminating the need for subsequent development of the exposed areas (as required for conventional resists). Pattern transfer from the film into gold and into silicon was investigated. Submicrometer patterns have been transferred from a 50‐nm‐thick PECVDa‐C:H film into a gold film by wet chemical etching. With a silicon substrate, the exposure process produced an etch‐resistant layer on the surface.

ISSN:0734-211X    

DOI:10.1116/1.588119

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Synthesis of electrostatic deflectors with given source parameters, first‐order properties, and minimum aberrations can be realized by using the cubic spline method or theapriorigiven multielectrode approach. Synthesis of electrostatic deflectors was successfully achieved previously by using the cubic spline method. In this paper we present synthesis of electrostatic deflectors based on theapriorigiven multielectrode approach for the purpose of obtaining the minimum beam spot size through a sequential optimization technique. Our calculations show that the third‐order geometrical deflection aberrations can be reduced by about two to three orders of magnitude using a multielectrode deflector with three units or five units, each having short cylindrical segments with geometrically octupole symmetry.

ISSN:0734-211X    

DOI:10.1116/1.588120

出版商:American Vacuum Society    

年代:1995

数据来源: AIP