摘要:

The microstructure of semiconductor metallization is becoming increasingly important as linewidths decrease below 0.5 μm. At these dimensions, reliability and performance are greatly influenced by specific microstructural features rather than only by the average material properties. In this article, we address the prospects for controlling the microstructure of thin film interconnection metals as linewidths are predicted to decrease below 0.1 μm by the year 2010. First, we evaluate the sources of energy available to drive microstructure changes in thin films, both during and after deposition. The internal energy sources considered are grain boundaries, interfaces, surfaces, strain, solidification, crystallization, solute precipitation, and phase transformations, with energy densities ranging from less than 1 meV/atom to greater than 100 meV/atom. The external energy sources considered are particle bombardment during deposition, mechanical deformation, and radiation damage, which may deliver energies greater than 100 eV/atom. Second, we review examples of microstructure changes in terms of these energy sources. These examples include the dependence of Al–Cu and Ti fiber texture on the roughness ofSiO2,orientation change and abnormal Cu grain growth coupled to the precipitation of Co in Cu–Co alloys, and in-plane orientation selection during phase transformation ofTiSi2in very narrow lines. A substantial degree of microstructure control is also achieved in films deposited with off-normal incidence energetic particle bombardment, which has been used to produce both in-plane and out-of-plane crystallographic orientations in metals (Mo, Nb), nitrides (AlN), and oxides(ZrO2).Drawing on these examples, we discuss the prospects for microstructure control in future semiconductor metallization with respect to the list of energy sources, the decreasing dimensions, and the changing fabrication processes. One mechanism in particular, discontinuous precipitation of supersaturated solute atoms, is highlighted as having a substantial amount of stored energy available to drive microstructure evolution, and may provide a means to more fully control the microstructure of semiconductor metallization.

ISSN:0734-211X    

DOI:10.1116/1.589407

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

The crystalline lattice and periodic grating features have been employed as reference scales for simultaneous calibration between the scanning tunneling microscope (STM) and atomic force microscope (AFM). This article describes the configuration and functions of a dual unit STM-AFM for length metrology. The system was developed on the basis of a dual tunneling unit STM (DTU-STM) in view of the fact that the application of DTU-STM was strongly limited by sample conductivity. In the dual unit STM-AFM, a STM serving as a reference unit and an AFM as a test unit were combined by using one singleXYscanner. Both the reference sample and the test sample were installed at the center of the scanner on either surface, and were imaged by STM and AFM units at the same time. The length of the test sample image was measured by counting the periodic features of the reference sample image. We present a detailed discussion about the structure and control of the dual unit STM-AFM. Some comparison results, respectively, using crystalline lattices and periodic grating features as reference scales for length calibration of test samples are also provided. Experiments show a satisfactory matching between the STM unit and the AFM unit when covering a wide scan range from 5 nm to 10μm. Using different standard reference scales, the system enables nanometer and/or sub-micron accuracy length metrology of microstructures with any conductivity.

ISSN:0734-211X    

DOI:10.1116/1.589408

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

We have successfully used scanning tunneling microscope-assisted chemical vapor deposition to fabricate magnetic nanostructures as fine as 5 nm wide and<2 nm high using ferrocene[Fe(C5H5)2]as the metal-organic source gas. The physical properties of these nanostructures were qualitatively characterized andex situmagnetic force microscopy measurements indicate these features are strongly magnetic.

ISSN:0734-211X    

DOI:10.1116/1.589409

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

We propose force modulation atomic force microscopy (FM)-(AFM) pit recording and demonstrate the possibility of achieving ultrahigh density recording with high speed readout. A minimum pit size of around 10 nm in diameter is formed by cold plastic deformation of the polycarbonate disk surface at a force of over 40 nN. Using a prototype of the rotation type FM-AFM pit recording system, an ultrahigh recording density of1.2 Tb/in.2and a readout speed of 1.25 Mb/s are demonstrated in 1/2(2,7) code recording.

ISSN:0734-211X    

DOI:10.1116/1.589410

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

Electron-beam deposition is used to fabricate free-standing carbon nanoelectrodes separated by a gap of less than 5 nm. Fabrication is carried out under direct visual control in an electron microscope. After coating the carbon electrodes with a thin metal film (e.g., AuPd) such structures can be used to study electrical transport properties of single molecules (e.g., conjugated polymers) or metal nanoclusters. The fabrication process of the nanowires is described in detail. Furthermore, we suggest electrostatic trapping as a new method to bridge the electrodes with a single conducting nanoparticle in a controlled way. This principle was tested successfully on Pd nanoclusters and carbon nanotubes.

ISSN:0734-211X    

DOI:10.1116/1.589411

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

There is distortion in atomic force microscope (AFM) images caused by a nonideal shape and size of the probe tip. This is called tip effect and is due to the convolution of the tip and sample. AFM images of nanometer size islands of zinc deposited on silicon substrates by the ionized cluster beam deposition technique were used to investigate this effect. The number of zinc atoms per unit area determined by each of two methods, the AFM images and Rutherford backscattering spectrometry (RBS) are compared and the AFM reported more zinc than RBS. A partial explanation for this difference is that the convolution of the tip and sample makes the islands appear larger in the AFM data. Previously reported convolution and deconvolution algorithms were implemented to study and simulate the interaction between tip and sample in the AFM. The deconvolution algorithm removes part of the distortion by taking into account the physical volume occupied by the tip which exposes a more accurate image. After deconvolution of the zinc islands images there was better agreement between AFM and RBS results. Deconvolution of other images will also be discussed.

ISSN:0734-211X    

DOI:10.1116/1.589412

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

ZnO ultrafine particle (UFP) films were deposited on glass andSiO2substrates by a direct current gas discharge activated reactive evaporation method. The effect of substrate temperature and annealing on the structure and morphology of ZnO UFP films was studied by x-ray diffraction and scanning electron microscope. The results show that the spherical island density decreases with increasing annealing temperature and the structure becomes polycrystalline with a (002) preferential orientation as the substrate temperature increases. In addition, angle resolved x-ray photoelectron spectroscopy was used to study the absorption of water on the ZnO UFP film surface by measuring the two deconvoluted peaks for O1s.The two deconvoluted peaks for O1swere located at 533.2 and 534.8 eV. The absorption coefficients of water on the surface were 0.52 and 0.43, respectively, for nonannealed and annealed ZnO UFP films.

ISSN:0734-211X    

DOI:10.1116/1.589413

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

Epi-ready Ge(111) surfaces were implanted with cobalt ions to doses of1016–5×1017ions/cm2at accelerating voltages of 40–70 kV. Cellular nanostructures were observed by contact mode and tapping mode atomic force microscopy (AFM). These are similar (at higher resolution) to those reported in earlier scanning electron microscope measurements. Image distortions observed in contact mode AFM are attributed to not only the effect of the tip size but also the change of the effective tip shape due to the softness and stickiness of the implanted surface layer. The variation of the root-mean-square roughness with ion dose (1016–1017ions/cm2), accelerating voltage (40– 70 kV), and mean beam current density (15–150μA/cm2)is presented and explained in terms of ion range and surface temperature.

ISSN:0734-211X    

DOI:10.1116/1.589414

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

A compact laser-plasma proximity x-ray lithography system suitable for laboratory-scale low-volume nanometer patterning is presented. The laser-plasma source, which is based on a fluorocarbon liquid-jet target, generates high-brightnessλ=1.2–1.7 nmx-ray emission with only negligible debris production. TheAu/SiNxx-ray mask is fabricated by employing ion milling and a high-contrast e-beam resist. With SAL-601 chemically enhanced resist we demonstrate fabrication of high-aspect-ratio, sub-100 nm structures. The exposure time is currently 20 min using a compact 10 Hz,λ=532 nm,70 mJ/pulse mode-locked Nd:YAG laser. However, the regenerative liquid-jet target is designed for operation with future, e.g., 1000 Hz, lasers resulting in projected exposure times of∼10 s.

ISSN:0734-211X    

DOI:10.1116/1.589490

出版商:American Vacuum Society    

年代:1997

数据来源: AIP

摘要:

Ion-beam exposure and patterning characteristics of an amorphousSe75Ge25thin film which acts as a positive resist in focused-ion-beam (FIB) lithography have been studied using low-energyGa+ion sources below 30 keV. Thea-Se75Ge25resist exposed to 10 keV defocused-Ga+ion beam with the dose of5.0×1014to9.3×1015 ions/cm2results in increasing the optical absorption, which was also observed in the film exposed to an optical dose of4.5×1020 photons/cm2.The absorption edge shift of 0.3 eV for the resist exposed to a dose of9.3×1015 ions/cm2at 10 keV is about twice that of photo exposure. These large shifts could be estimated as due to an increase in disorder, considering a decrease in the slope of the Urbach tail and a broad pattern of x-ray diffraction. For the exposure of a 30 keVGa+ion beam and above a dose of1.4×1015 ions/cm2,a 590-Å-thick resist film is completely etched by dipping for 10 s in 1:1:3HNO3:HCl:H2Osolution (25 °C), and then the etching rate is about 60 Å/s. As the incident energy increases from 10 to 30 keV, the threshold dose decreases from4.0×1015to1.4×1015 ions/cm2and then the imaging contrasts appear to be about 0.5 and 2.5, respectively. The decrease of the threshold dose with increasing the exposure energy is evidence that a predominant factor in the FIB exposure characteristics is the energy transfer rather than the implanted ions themselves. When 30 keVGa+FIB exposure with a multiscan diameter of 0.2 μm and the above-mentioned development are employed, a resist pattern with a linewidth of about 0.225 μm is obtained.

ISSN:0734-211X    

DOI:10.1116/1.589491

出版商:American Vacuum Society    

年代:1997

数据来源: AIP