A molecular self-assembly process based on the alternating deposition of a p-type doped electrically conductive polycationic polymer and a conjugated or nonconjugated polyanion has been developed. In this process, monolayers of electrically conductive polymers are spontaneously adsorbed onto a substrate from dilute solutions and subsequently built-up into multilayer thin films by alternating deposition with a soluble polyanion. In contrast to a deposition process involving the alternate self-assembly of polycations and polyanions, this process is driven by the electrostatic attractions developed between the p-type doped conducting polymer and the polyanion. The net positive charge of the conducting polymer can be systematically adjusted by simply varying its doping level. Thus, with suitable choice of doping agent, doping level and solvent, it is possible to manipulate a wide variety of conducting polymers into exceptionally uniform multilayer thin films with layer thicknesses ranging from a single monolayer to multiple layers.

Molecular beam epitaxy (202) with growing layer thickness control (206) by feedback of integrated mass spectormeter (204) signals. Examples include III-V compound structures with multiple AlAs, InGaAs, and InAs layers as used in resonant tunneling diodes.

A raster scan lithography system is modified so that the duration of illumination (dose modulation) for particular pixels is varied to lie between the full on and full off normally used. For instance, three levels of pixel intensity are provided, 100%, 70% and 30% (in addition to off which is 0%). The 30% and 70% pixels are used along the edge of a feature so as to locate the edge when written in between the lines of the cartesian raster scan grid. Thus the edges of the feature are moved off the grid, without the need for multiple passes. This pixel dose modulation uses three preset delay lines determining dwell times for each pixel on a pixel-by-pixel basis, as defined by a two (or more) bit deep memory file associated with the pattern to be written. Additionally, the pixel center locations are directly moved off the grid by deflecting the beam as it scans certain pixels located along feature edges. The amount of deflection is controllably variable to achieve various edge locations. This deflection is used by itself or in combination with dose modulation, and is implemented by an electrostatic deflector in the beam lens for an E-beam system.

Submicron device fabrication entailing ringfield x-ray pattern delineation is facilitated by use of a condenser including a faceted collector lens. The collector lens is constituted of paired facets, symmetrically placed about an axis of a laser-pumped plasma source. Each of the members of a pair produce an image of the entire illumination field so that inhomogeneities in illumination intensity are compensated within each composite image as produced by a particular pair.

A fiber probe is formed from a cladded optical fiber segment by isotropically etching a lower portion of the fiber segment, followed by cleaving the resulting etched lower portion. The resulting cleaved endface of the fiber segment is then coated with a protective layer which is then patterned by exposure to optical radiation propagating down the core of the fiber segment followed by development. A plasma etching, masked by the thus patterned protective layer, removes a desired height of cladding in the neighborhood of the cleaved endface. Finally, the lower regions of the fiber segment are subjected to a further etching to reduce the width of the tip to a desired value.

An electron beam system for direct writing applications combining the parallel throughput of a projection system and the stitching capability of a probe-forming system employs an electron gun to illuminate an initial aperture uniformly, a first set of controllable deflectors to scan the beam over the reticle parallel to the system axis, impressing the pattern of a subfield of the reticle in each exposure, in which a first variable axis lens focuses an image of the initial aperture on the reticle, a second variable axis lens collimates the patterned beam, a second set of controllable deflectors to bring the beam back to an appropriate position above the wafer, and a third variable axis lens to focus an image of the reticle subfield on the wafer, together with correction elements to apply aberration corrections that may vary with each subfield, thereby providing high throughput from the use of parallel processing of the order of 107 pixels per subfield with the low aberration feature of the variable axis lens and the ability to tailor location-dependent corrections that are associated with gaussian systems that stitch the image pixel by pixel.

A direct-writing electron beam is used for defining features in a resist layer and hence ultimately in an underlying workpiece, such as in a phase-shifting mask substrate or a semiconductor integrated circuit wafer. The resist layer is located on a top major surface of the workpiece. In a specific embodiment, the resist layer is located underneath a protective layer of polyvinyl alcohol (PVA); and a grounded conductive layer, such as a conductive organic layer, is located on the protective layer. After exposing the top major surface of the resulting structure to the direct-writing electron beam, the following steps are performed: (1) a plasma etching completely removes the entire thickness of the conductive layer as well as a small fraction of the thickness of the PVA layer; (2) the PVA layer is then completely removed by dissolving it in water; (3) another plasma etching removes a small fraction of the thickness of the resist layer, including any unwanted residues; and (4) the resist layer is developed.

A workpiece is patterned in accordance with the lateral pattern of a spatially selective, electrically charged, scanning beam of actinic radiation by:- (1) directing the beam at a major surface of a conductive layer (13) that is located overlying a resist layer (11) that is sensitive to the beam, the conductive layer being transparent to the beam, the resist layer being located overlying the workpiece; (2) removing the entire thickness of the conductive layer by means of dry etching; (3) developing the resist layer, whereby the resist layer becomes a patterned resist layer in accordance with the pattern of the beam.

An ohmic contact to a p-type zinc selenide (ZnSe) layer (17) in a Group II-VI semiconductor device, includes a zinc mercury selenide (ZnxHg1-xSe) or zinc telluride selenide (ZnTexSe1-x) layer (19) on the zinc selenide layer, a mercury selenide (HgSe) layer (18) on the zinc mercury selenide or zinc telluride selenide layer and a conductor (such as metal) layer on the mercury selenide layer. The zinc mercury selenide or zinc telluride selenide and mercury selenide layers between the p-type zinc selenide and the conductor layer (13) provide an ohmic contact by eliminating the band offset between the wide bandgap zinc selenide and the conductor. Step graded, linear graded, and parabolic graded layers of zinc mercury selenide or zinc telluride selenide may be provided. The ohmic contact of the present invention produces nearly ideal voltage-current relation, so that high efficiency Group II-VI optoelectronic devices may be obtained. The integrated heterostructure is formed by epitaxially depositing the ohmic contact on the Group II-VI device. A removable overcoat layer may be formed on the Group II-VI device to allow room temperature atmospheric pressure transfer of the device from a zinc based deposition chamber to a mercury based deposition chamber, for deposition of the ohmic contact. The integrated heterostructure may also be formed by forming an optical emission heterostructure including an epitaxial ohmic contact on a first substrate, bonding the ohmic contact to a second substrate, and then removing the first substrate.

An inverted integrated heterostructure includes an optical emission heterostructure formed of Group II-VI compound semiconductor materials having first and second opposing faces and including a layer of p-type zinc selenide or an alloy thereof at the first face. A zinc mercury selenide or a zinc telluride selenide layer is formed on the layer of p-type zinc selenide or an alloy thereof, and a mercury selenide layer is formed on the zinc mercury selenide or zinc telluride selenide layer, opposite the optical emission heterostructure. An ohmic electrode is formed on the mercury selenide layer opposite the zinc mercury selenide or a zinc telluride selenide layer, and a transparent ohmic electrode is formed on the second face of the optical emission heterostructure for allowing optical emissions from the optical emission heterostructure to pass therethrough. The ohmic electrode is preferably an optically reflecting ohmic electrode for reflecting optical emissions from the optical emission heterostructure back into the optical emission heterostructure. A substrate is also preferably included on the ohmic electrode opposite the mercury selenide layer. The substrate is preferably an electrically and thermally conducting substrate. The integrated heterostructure may be formed by forming an optical emission heterostructure including an epitaxial ohmic contact on a first substrate, bonding the ohmic contact to a second substrate and then removing the first substrate.