Focused ion beam ͑FIB͒ methodologies for successfully milling copper ͑U.S. Patent No. 6,322,672 B1͒ have been demonstrated. Approaches to milling copper ͑Cu͒ are required because standard FIB mill procedures produce rough, uneven cuts that are unsuitable for circuit edits, a principal FIB function. Efforts to develop gas assisted etching ͑GAE͒ processes which would smoothly mill Cu failed because Cu halides are not volatile and remain on the substrate as corrosive electrically conductive debris. Single crystal studies show that Cu grains with different crystal orientations vary in mill rate by as much as 4ϫ. Moreover, the ͑110͒ crystal orientation, which mills most slowly, forms a Cu 3 Ga phase when milled with a focused Ga ion beam. This phase is particularly resistant to milling and, in polycrystalline Cu, propagates during the milling operation, contributing to the uneven trench profiles. CoppeRx, a novel scan strategy, cleanly and uniformly removes polycrystalline Cu with minimal damage to the underlying dielectric. CoppeRx minimizes the formation and propagation of the Cu 3 Ga phase and equalizes the etch rates of the Cu crystal orientations. The CoppeRx strategy includes the milling of an ''egg crate'' topography to minimize the propagation of the Cu 3 Ga phase and the creation of a heavy atom sacrificial layer of the Cu surface ͑U.S. Patent Application No. 20010053605͒ which scatters the incident Ga ion beam, thereby reducing the channeling influence on Cu milling rates. This heavy atom layer is created by flowing W͑CO͒ 6 vapor during the FIB milling process. The CoppeRx scan strategy is especially beneficial for milling thick ͑Ͼ0.8 m͒ Cu structures with large, prominent grains. Because Cu interconnect lines are relatively thin ͑Ͻ0.4 -0.5 m͒, grain-related milling roughness is less of a problem. The CoppeRx egg crate topography and W scattering layer are not required. Instead, the successful cutting of 40 ohm Cu interconnect lines to produce Ͼ20 M ohm open circuits is achieved by flowing O 2 or H 2 O during the milling process ͑U.S. Patent No. 6,322,672B1͒. The O 2 /H 2 O flow smoothes the Cu milling by producing an amorphous surface oxide, thereby reducing channeling, and by enhancing the etch selectivity for Cu relative to the surrounding and underlying SiO 2 based dielectric. These interconnect cuts have been routinely done at the bottom of high aspect ratio holes ͑e.g., 1ϫ1ϫ9 m͒.

ABSTIMCTAn x-ray zone plate was fabricated using the novel approach of focused ion beam (FIB) milling. The FIB technique was developed in recent years, it has been successfully used for transmission electron microscopy (TEM) sample preparation, lithographic mask repair, and failure analysis of semiconductor devices. During FIB milling, material is removed by the physical sputtering action of ion bombardment. The sputter yield is high enough to remove a substantial amount of material, therefore FIB can perform a direct patterning with submicron accuracy. We succeeded in fabricating an x-ray phase zone plate using the Micrion 9500HT FIB station, which has a 50 kV Ga+ column. Circular Fresnel zones were milled in a 1.Opm-thick TaSiN film deposited on a silicon wafer. The outermost zone width of the zone plate is 170 nm at a radius of 60 pm. An achieved aspect ratio was 6:1.

Purification and crystallization of tungsten wires fabricated by focused-ion-beam-induced deposition Appl. Phys. Lett. 86, 192112 (2005); 10.1063/1.1927714 Microstructural comparisons of ultrathin Cu films deposited by ion-beam and dc-magnetron sputtering J. Appl. Phys. 97, 093301 (2005); 10.1063/1.1886275 Evolution of tungsten film deposition induced by focused ion beam

The magnetotransmission of a p-type Hg,,,,Cd,.,,,Te bicrystal containing a single grain boundary with an inversion layer has been investigated in the submillimetre wavelength range. For the first time t h e cyclotron resonance lines belonging to the various electric subbands of a quasi-two-dimensional carrier system at a grain boundary could be detected. The measured cyclotron masses and the subband densities determined from Shubnikov-de Haas experiments are compared with theoretical predictions and it is found that the data can be explained very well within the framework of a triangular well approximation model which allows for non-parabolic effects.

Magnetotransport experiments on an electron accumulation system at the interface between t h e narrow-gap semiconductor cadmium mercury telluride (Hg,,Cd,Te (CMT)) and a passivating anodic oxide yield data of an extremely high quality and t h e first observation of t h e quantum Hall effect in this system. It is shown that the quality of the observed data is a result of a sharp increase in the resistivity of t h e bulk n-type CMT in a magnetic field. T h e Landau level structure of the system is calculated using a very simple scheme adapted from one originally devised for a two-dimensional system in lnSb a n d the conductivity tensor component oxx is modelled. The alternative assumptions of fixed carrier concentration and fixed Fermi energy are found to givenearly equivalent results and a good qualitative agreement with experiment is found. Estimates of the Landau level broadening parameters are made and the zerofield electron mobilities implied by these are ComDared with those deduced from cyclotron resonance measurements.