摘要:

Ultraviolet (UV) blocking filters are needed for atomic flux imaging in environments where high levels of ultraviolet radiation are present. Freestanding gratings are a promising candidate for UV filtering. They have a high aspect ratio (∼13), narrow (∼40 nm) slots, and effectively block UV radiation. The grating fabrication process makes use of several etching, electroplating, and lithographic steps and includes an optional step to plug pinholes induced by particles during processing. Gratings were successfully manufactured and tested. Measured UV transmissions of∼10−5and particle transmissions of ∼10% are in agreement with theoretical predictions.

ISSN:1071-1023    

DOI:10.1116/1.590434

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We have tested nanoimprint lithography, a new and promising technique for nanometer-scale pattern definition. Preliminary experiments reveal that, besides severe sticking and adhesion problems, the problem of material transport is one inherent to this technique. There are clear indications that most of the effects found may be understood in terms of material transport. We performed experiments within a well defined pressure and temperature window which ranged from 60 to 100 bar and from 50 to 90 °C above the glass transition temperature of the poly(methylmethacrylate)-like polymer used. As a result, the quality of imprint is evaluated with respect to full area pattern transfer, based on a qualitative scanning electron microscope investigation of the fully imprinted area of 2 cm × 2 cm patterned with features of different size and shape. Optimum conditions for imprint quality are found around 100 bar and 90 °C aboveTgfor the specific polymer used. Although material transport will limit nanoimprint performance in general, it is found that periodic patterns and isolated or small area negative stamp relief patterns are most suitable for high quality nanoimprinting.

ISSN:1071-1023    

DOI:10.1116/1.590436

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Five multilayer resist methods (three positive tones and two negative tones) have been devised for nanoimprint lithography on nonflat surfaces. Three of the methods have been demonstrated experimentally on aSiO2surface with 100 nm deep sharp steps. The advantages and disadvantages of each method are discussed. Our results should be applicable to nanoimprint lithography with 10 nm feature size on nonflat surfaces.

ISSN:1071-1023    

DOI:10.1116/1.590437

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

An alternative approach to flat nanoimprint lithography (NIL)—roller nanoimprint lithography (RNIL) is demonstrated. Compared with flat NIL, RNIL has the advantage of better uniformity, less force, and the ability to repeat a mask continuously on a large substrate. Two methods for RNIL are developed: (a) rolling a cylinder mold on a flat, solid substrate; (b) putting a flat mold directly on a substrate and rolling a smooth roller on top of the mold. Using our current roller nanoimprint system, sub-100 nm resolution pattern transfer has been achieved.

ISSN:1071-1023    

DOI:10.1116/1.590438

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

A new technique for performing chromeless phase shift optical nanolithography is presented. Phase masks have been wet etched into silicon nitride membranes, using either hotH3PO4or HF. Contact exposure through these masks results in developed photoresist features as small as 90 nm, even for masks with shallow sidewall slopes. The observed effect is attributed to the presence of an abrupt phase step at some point on the wet etch profile, although this does not need to correspond to a π phase shift in order to obtain good contrast exposures. Simulations have been performed for typical wet-etching profiles, and it is found that good contrast is expected for a very wide range of etch depths. In addition, the width of the null in the near-field intensity profile varies with etch depth, indicating that control of feature size is possible. This technique is simple and inexpensive, making it an attractive candidate for nanopatterning a wide variety of substrates.

ISSN:1071-1023    

DOI:10.1116/1.590439

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We have developed a fabrication process of Si nanopillars using metal clusters arranged by electron beam (e-beam) lithography. This process forms nanopillars by taking advantage of the fact that metal clusters deposited on Si substrates act as nuclei for self-formation of etch masks during electron cyclotron plasma etching withSF6if the substrate is kept at ∼−135 °C. The clusters are placed on the substrate by an e-beam lift-off technique following a small amount of deposition of metal vapors. Arrays of Si pillars with a regular spacing of 100 nm were actually fabricated using Au, Ag, and Fe clusters. Au clusters yielded 70 nm high pillars with an average diameter of 10 nm and a standard deviation of 1.3 nm, which is exceedingly better than the resolution of the lithography used (∼30 nm). Ag and Fe clusters produced pillars 20 nm in diameter. These results demonstrate that the pillar size is controlled by species of the metal clusters, whereas the position is defined by the e-beam lithography. We have also found that Fe clusters are very durable in the etching process and can produce pillars with a very high aspect ratio: 280 nm high and 20 nm in diameter.

ISSN:1071-1023    

DOI:10.1116/1.590440

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We used a side view transmission electron microscopy (TEM) technique which allows us to study the oxidation process of Si dots onSiO2systematically for different dot sizes, oxidation times, and temperatures. Using energy filtering TEM (EFTEM) an excellent contrast between Si andSiO2is achieved, independent from the crystal orientation. Si dots onSiO2with initial diameters from 10 to 60 nm were oxidized with different oxidation times at 850 °C. The resulting shapes of theSiO2and the embedded Si cores were determined from the EFTEM micrographs. A strong retardation of the oxidation process compared to planar oxidation as well as a self-limiting effect for long oxidation times are reported. Furthermore a pattern dependent oxidation is observed, depending on the aspect ratios of the dots.

ISSN:1071-1023    

DOI:10.1116/1.590441

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Thin silicon membranes on silicon on insulator substrates are used to fabricate point contacts with a well-defined interface in the nanoconstriction between the two metal electrodes. Transmission electron microscope images of heterointerfaces in conjunction with energy dispersive x-ray analysis of the interfacial region show the capabilities of the process and its limitations. The latter involve material-specific phenomena on a nanoscale, such as an interfacial reaction between a metal film andSiO2and metal diffusion across the heterointerface. These adverse effects can be avoided by a proper choice of the metals and the deposition temperature, as demonstrated with results of electrical measurements on a Au/Cu heterocontact.

ISSN:1071-1023    

DOI:10.1116/1.590442

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The fabrication and performance of a microprobe with multipurpose capabilities for scanning probe microscopy is presented in this article. Atomic force microscopy (AFM), scanning capacitance microscopy, and electrostatic force microscopy measurements can be simultaneously performed with the probe in which a silicon tip is integrated with a piezoresistive cantilever. Fabrication of the microprobe is based on double side bulk/surface micromachining of silicon on insulator (SOI) substrates. The novelty of this device is a highly doped silicon tip with a curvature radius of about 20 nm which is electrically isolated from the silicon cantilever by the buried oxide layer of the SOI substrate. At the beam supporting point a piezoresistive Wheatstone bridge is fabricated to allow the deflection of the microtip to be monitored. This cantilever displacement detection system enables measurements in vacuum and simplifies the design of the AFM head. Experimental measurements agree well with theoretical estimates of the sensitivity of the microprobe.

ISSN:1071-1023    

DOI:10.1116/1.590443

出版商:American Vacuum Society    

年代:1998

数据来源: AIP