Showing papers on "Electron-beam lithography published in 1973"

Ion beam micromachining of integrated optics components.

Abstract: Thin film integrated optics components such as light guides, modulators, directional couplers, and polarizers demand high quality edge smoothness and high resolution pattern formation in dimensions down to submicrometer size. Fabrication techniques combining holographic and scanning electron beam lithography with ion beam micromachining have produced planar phase gratings with intervals as small as 2800 A, guiding channel couplers in GaAs, and also wire- grid polarizers for 10.6-µm radiation.

X-Ray Lithography: A Complementary Technique to Electron Beam Lithography

Abstract: X-ray lithography provides a means of replicating, in a single large-area exposure, submicron linewidth patterns made by scanning electron beam lithography. The technique is complementary to existing electron beam technology, and provides a number of unique advantages: (i) it is simple and inexpensive; (ii) the penetrating character of x-rays makes it relatively insensitive to contamination; (iii) both positive and negative type resists can be used; and (iv) because of the absence of backscattering effects, both positive and negative type patterns can be made with equal facility. Exposure times of seven minutes have been achieved for 3 μ mask-sample gaps. This can be decreased to less than one minute by using a rotating anode, or by reducing the mask-sample gap. The most recent results in x-ray lithography are reported, including the fabrication of surface wave devices. The elements of a multiple-mask alignment system are described. This system should permit the rapid and automatic superposition on a substrate of patterns from several different masks, to a precision of 1/10 μ.

Fundamental aspects of electron beam lithography. I. Depth‐dose response of polymeric electron beam resists

Abstract: The application of a phenomenological depth‐dose theory to the exposure of negative electron resists is described in detail. The model predicts a cross‐linking rate dnc/dt=(Gc/100) × (J0/e)(Va/RG)Λ(f) cm−3 sec−1, where Gc is the number of crosslinks produced per 100 eV lost in the polymer. Jo is the incident current density, Va the initial kinetic energy, RG the electron Grun range, and Λ(f) the depth‐dose function in terms of the normalized penetration f=z/RG. Since the G value of a negative resist decreases with exposure, it is suggested that a more meaningful parameter characterizing a negative resist is the absorbed energy required to gel the polymer at the resist‐substrate interface. This interface or threshold gel energy density, Eg(i), is independent of the beam parameters and varies from about 1022 eV cm−3 for polyvinyl ferrocene to 3.8×1018 eV cm−3 for epoxidized polybutadienes. The model predicts that the threshold sensitivity should vary as Va0.75 which agrees reasonably well with published exp...

Model for Exposure of Electron-Sensitive Resists

Abstract: A mathematical model for the exposure of electron-sensitive resists on a structure coated with a thin layer of resist is presented. The calculations yield contours of equal absorbed energy density in the resist and these are interpreted as the contours which bound the resist after development. We calculate the exposure for an electron beam of vanishingly small cross-section, a beam of Gaussian current-density distribution, single lines, parallel lines, and areas.

Fundamental aspects of electron beam lithography. II. Low‐voltage exposure of negative resists

Abstract: A study has been made of the use of low‐voltage exposure of negative resists for electron lithography. Three resists have been investigatd; an esterified terpolymer, epoxidized polybutadiene, and polyglycidyl methacrylate. The optimum exposure conditions have been determined for each material, and the use of a low accelerating voltage (5 kV) found to be advantageous. The application of this technique for the pattern delineation of silicon dioxide and tungsten is described.

Epoxy-polymer electron beam resists

Abstract: Disclosed is a method of making patterned negative electron beam resists by first mixing but not reacting an epoxy with a polymer. The epoxy-polymer mixture is then applied to a support in the form of a thin film. Upon irradiating a portion of the thin film with an electron beam according to a programmed pattern, the epoxy links with the polymer, thereby causing cross linkage of the polymer and making the irradiated portion insoluble in certain solvents. The remainder of the epoxy-polymer mixture is soluble in the solvent, thereby dissolving in the solvent and removed, resulting in the desired pattern of openings in the electron beam resist.

Manufacture of masks

Abstract: A method of, and apparatus for, fabricating masks in which the mask pattern is defined by electron beam exposure of electron beam sensitive resist on a surface of a mask blank. A metal layer on the mask blank incorporates reference markings which cause changes in secondary electron emission during scanning of the electron beam to effect the desired exposure pattern, from which correction signals are derived. The correction signals are used to adjust the electron beam deflection throughout the exposure process so that the final exposed pattern is accurately aligned with reference markings. A metal layer is then formed on the resist and the unexposed portions of the resist, as well as unoverlying and underlying metal areas, are removed to leave a metal pattern on the mask blank corresponding with the pattern exposed in the resist.

A Simple Flying Spot Scanner Design for Electron Lithography

Abstract: A simple, inexpensive flying spot scanner system is described which enables a conventional scanning electron microscope (SEM) to be used for research projects in electron beam lithography. The unit, built almost entirely from readily purchased parts, bolts onto the SEM without any modification of the microscope itself. The ultimate resolution of the system exceeds 45 line pairs/cm over a 9 cm square frame, giving over 900 beam on, beam off operations per frame. The system has been used with electron lithography to etch thin films into patterns of considerable complexity with linewidths of less than 5000 A.