Showing papers on "Lithography published in 1984"

Repetitively pulsed-plasma soft x-ray source.

Abstract: A 10-Hz Nd:YAG laser system with 0.6-J, 25-nsec pulses was used to produce plasmas which emitted strongly in the soft x-ray region. Spectral, temporal, and spatial characteristics of these plasma emissions are presented together with an application of the source to soft x-ray lithography.

X-ray lithography system

Abstract: An x-ray lithography system is disclosed in which x-rays are generated by directing a high energy laser beam against a metal target to form an x-ray emitting plasma. The x-rays from the plasma are then directed through a mask towards a resist covered wafer to cause a patterned exposure on the wafer resist coating. The mask, the portion of the target which the laser beam strikes and the portion of the wafer to be exposed are all within an evacuated chamber. The laser, prior to entering the chamber, is split into two separate beams, each of which are focused and directed through a window in the side of the chamber towards the same spot on the target. Apparatus, including an air bearing, seal and positioner, is provided to move the target at periodic intervals. Similar apparatus is provided to move the wafer from exposure section to exposure section. The laser beam system includes a face pumped laser beam amplifier and unidirectional beam expanders to allow the maximum energy to be transferred to the laser beam by the amplifier. A series of two or more laser pulses are provided in order to maximize the energy obtained from the laser amplifier. A magnet and a membrane shield are also provided to prevent high energy particles and dust contaminants from the plasma from effecting the lithography process. A materials handling device is provided for moving wafers, targets and masks and an alignment system operating within the evacuated chamber, positions of the wafer with respect to the mask prior to the exposure thereof.

Method for making optically enhanced thin film photovoltaic device using lithography defined random surfaces

Abstract: The present invention is a method for producing an optically enhanced thin film photovoltaic device. The method includes the steps of producing an active layer of semiconductor material wherein the surface of at least one side of the active layer is textured such that the surface includes randomly spaced, densely packed microstructures of predetermined dimensions of the order of the wavelength of visible light in the semiconductor material and attaching a reflecting surface directly to one side of the semiconductor material and making an ohmic contact to the material.

10-nm resolution electron-beam lithography

Abstract: An analytical electron microscope has been used to fabricate a variety of ultrasmall structures and to test the size limits and some basic concepts of high‐resolution electron‐beam lithography. Arbitrarily shaped patterns on both thin film and bulk substrates have been written with dimensions of approximately 10 nm. A review of devices, structures, materials, and techniques is presented.

Waveguide grating lenses for optical couplers.

Abstract: New waveguide grating lenses for coupling a guided wave to a spherical wave, focusing in the air, have been designed. The lenses have the advantages. of high efficiency and high practicability for fabrication. Chirped and curved grating lenses were fabricated on PMMA waveguides by an electron beam exposure system.

Submicron, vacuum ultraviolet contact lithography with an F2 excimer laser

Abstract: An F2 excimer laser at 157 nm has been used for the first time as an exposure source for high resolution photolithography. At this short wavelength, conventional glass and quartz mask substrates are opaque, and therefore alkaline‐earth halides and sapphire were used as mask substrates. The masks were patterned by electron beam lithography, and mask features as narrow as 150 nm have been replicated and represent the smallest features yet produced by contact photolithography.

System for real-time monitoring the characteristics, variations and alignment errors of lithography structures

Abstract: A system for evaluating and measuring the performance of lithographic structures, and more particularly for monitoring the optical parameters of a projection lithography system which uses the instant electrical readout from an array of photosensitive detectors fabricated on a silicon wafer in combination with a computer for real-time characterization of lithographic devices and the evaluation of optical E-beam, ion-beam and X-ray parameters. The system includes a source radiation, such as a source of ultraviolet light, a projection mask which masks the illumination from the source. The illumination is then directed through a projection lens onto a semiconductor wafer mounted on an x-y stepping table. A standard digital data processor is provided to control the x-y drive mechanism for the stepping table. The computer also controls a Z drive mechanism for movement in a vertical direction. The semiconductor wafer contains a plurality of radiation detectors which are responsive to the radiation from the source. These detectors use a conventional power supply controlled by the computer, and employ an output signal means which obtains the radiation produced output signals from the detectors and applies them to the computer. The use of a unique mask with the radiation-sensitive detectors is employed in combination with compiling means for the purposes of evaluating image projection from a lithographic system, including the properties of intensity, modulation transfer function (MTF), focus and alignment.

Continuous-wave operation of 1.5 μm distributed-feedback ridge-waveguide lasers

Abstract: CW operation of 1.5 μm ridge-waveguide DFB lasers is reported for the first time. The ridge-waveguide DFB laser structure offers the prospect of high modulation speeds due to the absence of parasitic capacitances associated with reverse-biased current-blocking layers. These devices also represent the first report of CW operation of DFB lasers fabricated using the hybrid LPE/MOCVD crystal-growth technique and also of DFB lasers with gratings produced by electron-beam lithography.

X-ray lithography system

Abstract: A system is provided for producing plasma pinch X-rays usable in X-ray lithography. Ionized heated plasma is repeatably generated in a first area directly from solid material without exploding the latter. X-rays are generated in a second area by passing high current through the plasma causing radial inward magnetic field pinching. Accurate control and improved intensity performance, and greater flexibility in selection of X-ray emitting materials, are provided by the separation of the plasma generating and the X-ray pinch generating functions. Common electrode structure is provided for plasma generating and for plasma pinching, which common electrode also provides a cylindrical plasma communication passage from the first to the second area, and provides an X-ray emission passage of desired axial orientation.

Polysilane Bilayer uv Lithography

Abstract: Polysilanes are a class of Si-Si backbone polymers that have been demonstrated to function as high resolution positive resists with excellent uv sensitivity. These materials have a unique photochemistry with high quantum yields and nonlinear bleaching. Polysilanes serve as excellent RIE barriers for bilevel resist applications because a protective layer of SiO 2 is formed during exposure to an oxygen plasma. Aliphatic polysilanes have been applied to full wafer mid-uv lithography with 0.75 μm resolution.

Contrast Enhanced UV Lithography With Polysilanes

Abstract: Contrast enhanced lithography has been been applied to mid-uv projection lithography with a new class of CEL materials, polysilanes. The nonlinear bleaching photochemistry of polysilanes provides a unique "bleaching latency" for contrast enhanced lithography. SAMPLE resist exposure and development simulation is compared with experimental CEL resist images using AZ2400® photoresist. The contrast enhancement gained with the use of polysilanes is examined as a function of exposure dose, image size, and contrast enhancement film thickness.

The range of light ions in polymeric resists

Abstract: The technique of ion beam lithography coupled with calculations using a Monte Carlo computer program for ion penetration in solids have been used to obtain various range parameters of hydrogen, helium, lithium, beryllium, boron, and carbon ions in polymethyl methacrylate resist. In the experiment, the resist is bombarded with ions and then developed in a 1 : 1 solution of methyl isobutyl ketone and isopropyl alcohol with the developed depth monitored as a function of time. The saturated developed depth is approximated as the mean path length of the ion in the resist. The physical basis of this approximation is discussed. The projected ranges and straggles of the specified ions at energies of 5–300 keV obtained by fitting the experimental data to the total range using a Monte Carlo program are presented. These range data can be used as guidelines to determine the resist mask thickness for ion implantation and for choosing resist thickness in ion beam lithography.

Device lithography using multi-level resist systems

Abstract: In order to hard-bake the bottom resist layer of a tri-level resist system for patterning a device wafer, the resist is subjected to a positive ramp heating step (of increasing ambient temperatures).

Mask ring assembly for X-ray lithography

Abstract: This invention is directed to a mask ring assembly for X-ray lithography which is particularly adapted, among other possible uses, for use in replicating integrated circuit patterns, said assembly including a mask ring, a plurality of kinematic mounts for removably mounting the mask ring on an alignment cartridge, each of the kinematic mounts including a funnel-like shaped seat member and a mating ball-like shaped member, one of said members being on the mask ring and the other of the members being mounted on the alignment cartridge.

B-Si masks for storage ring X-ray lithography

Abstract: The fabrication of masks used in storage ring X-ray lithography is described. These masks consist of a gold absorber electroplated over a substrate formed by a thin boron-doped silicon membrane covered by a layer of polyimide. Measurement of the properties of the materials which are of concern in this application is also described.© (1984) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

High-performance micro-Fresnel lens fabricated by UV lithography

Abstract: A micro-Fresnel lens 2 mm in diameter with an F/No. of 1 has been designed and fabricated by ultraviolet lithography. Experimental results show that the fabricated lens has diffraction-limited focusing characteristics and 38% diffraction efficiency.

A composition of matter of use as a resist in lithography

Abstract: A composition of matter is obtained by interreacting a quinone diazo compound and an organosilicon compound. Such a composition can be used as a resist in a lithographic process.

X-Ray lithography system

Abstract: The present invention is directed to X-ray lithographic systems, which are characterized by a plurality of work stations, a cartridge in which a wafer and mask are mounted, apparatus for moving the cartridge between the stations, apparatus for moving the cartridge within each station to a kinematic mount, and said kinematic mounts in all of the stations being substantially identical.

Si MOSFET fabrication using focused ion beams

Abstract: Submicrometer focused ion beams have been used both for the maskless ion implantation of p-channel depletion-mode Si MOSFET's and for the gate lithography of n-channel enhancement-mode Si MOSFET's. B-Pt and Au-Si liquid-metal-alloy ion sources were utilized in a single-lens focusing column for the implantation and lithography steps, respectively. An 800-A-thick Al stopping layer was used at the target to separate the lighter ions from the heavier ion species in the beams. Reasonable dc electrical characteristics were measured for the chosen device process parameters.

Design of an E 2 PROM memory cell less than 100 square microns using 1 micron technology

Abstract: In this paper, the design of a state of the are E2PROM memory cell is presented. This memory cell is being incorporated in a third generation electrically erasable non-volatile memory technology based on 1 µm lithography. The 1 µm lithography is being used aggressively in the design of the memory cell to achieve the highest feature density. The memory cell is 13.5 µm in Y dimension and 7 µm in X dimension. The basic philosophy of the design is the maximization of coupling ratio, both in program and erase. This allows the use of a thicker tunnel oxide to give the highest yield and reliability. The tunnel oxide area is defined by two masking steps instead of one in competitive designs to minimize the drain capacitance, giving higher erase coupling ratio and thus a larger window. It will be shown that this is a very solid and reliable cell that will be used in high density E2PROMs.

Device fabrication by nanolithography and electroplating for magnetic flux quantization measurements

Abstract: 100‐keV e‐beam lithography and electroplating of gold have been used to fabricate a device for the measurement of quantum changes in magnetic flux. The structure is defined in a 200‐nm‐thick layer of a copolymer of methyl methacrylate and methacrylic acid (PMMA/MAA) on top of a Si wafer covered by 150 nm of Si3N4. The device is a square frame of 2×2 μm2 and 100‐nm linewidth. Gold was electroplated to a thickness of 100 nm. This technique allows the fabrication of high resolution, high aspect ratio gold structures.

Fabrication Of Free-Standing X-Ray Transmission Gratings And Zone Plates

Abstract: Free-standing transmission gratings and zone plates which are to be used as dispersion elements for x rays have been fabricated with UV holography and x-ray lithography.

Electron beam lithography — influence of molecular characteristics on the performance of positive resists

Abstract: Polymers are widely used as resists in electron beam lithography. This paper is concerned with theoretical modelling of the electron beam lithographic process and establishing criteria which need to be satisfied for a polymer to behave as a good positive resist. The effects of molecular weight, tacticity, solvent selection and sequence structure are discussed. Criteria are presented upon which the design of a new resist material may be based.

Polymethyl methacrylate resist sensitivity enhancement in x‐ray lithography by in situ polymerization

Abstract: X‐ray‐induced grafting of acrylic acid to poly (methyl methacrylate) (PMMA) increases the resist sensitivity by at least three orders of magnitude. Scanning electron microscopy of grafted PMMA revealed micron and submicron features for dose levels as small as 0.1–1 mJ/cm2, thus demonstrating the possibility of using this technique for x‐ray lithography.

Electron beam peripheral patterning of integrated circuits

Abstract: Silicon wafers are imprinted with microelectronic circuit patterns by firstithographing the outlines or peripheries of all circuit features of a given wafer level by means of a narrow line formed by direct-writing electron beam lithography utilizing a positive electron resist, then using proximity photoprinting to complete the lithography of that level using a positive photoresist and a photomask with oversized opaque areas so that the pattern edges on the wafer exposed to the flux passing through the photomask will fall within the peripheral lines formed by the electron beam.

Submicron Lithography by Demagnifying Electron-Beam Projection

Abstract: Demagnifying electron-beam projection is a technique well suited to generate submicron structures for various applications. A two- or three-lens projection system demagnifies a selfsupporting master stencil into a registration plane. The stencil is fabricated by optical or electron-beam lithography in conjunction with standard planar etching and plating technologies. The design rules for reducing image projection lens systems are discussed. To produce nanometer structures from micrometer master structures large reduction factors are to be used. For inspection of the recorded nanometer pattern a conventional transmission electron miscroscope (CTEM) is an adequate tool. A single field condenser objective lens offers the advantage to control the diminishing and the magnifying objective lens field by one lens excitation.

Optical heat-insensitive mask for X-ray lithography, and manufacturing process thereof.

Abstract: In conventional optical masks for X-ray lithography, which consist of a support layer and an absorber structure applied to one side, the heating occurring during the exposure due to the different coefficients of thermal expansion of support and absorber material results in bending of the optical mask (bimetallic effect) In the heat-insensitive mask according to the invention, on the other hand, the absorber structure 102, 103 is applied symmetrically with respect to the layer centre 106 of the support layer 101 in terms of its layer thickness, so that the forces due to the heating are self-compensating in terms of bending moment