Showing papers on "Resist published in 1973"

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.

Electron-Beam Fabrication of Ion Implanted High-Performance FET Circuits

Abstract: This paper describes the design, fabrication and test results of a high-performance IGFET circuit made by combining electron-beam technology for all masking steps and ion implantation for the diffusion steps. The circuit consists of an eleven stage ring oscillator with two FET devices per stage. The enhancement mode device is the switching element and the depletion mode is used as load. The aluminum gate length of the devices is 1 μ and the width is 5 μ. The aluminum metallization, defined with electron-beam exposure of PMMA resist, also serves as a self-aligning mask for the ion implantation of source and drain in the gate region. The average delay per stage was determined by measuring the periodicity of the circuit oscillation and dividing by 22. Test results on several circuits indicate that the average delay per stage is approximately 295 psec.

Electron-Resist Fabrication of Bends and Couplers for Integrated Optical Circuits

Abstract: The fabrication of complex integrated optical circuits using thin films will require dielectric patterns of high resolution and edge smoothness. This paper describes an electron-beam technique that has been used to form a curved thin-film light guide and a directional coupler, and is applicable to filters and other more complex components.

The Preparation and Properties of a Polysiloxane Electron Resist

Abstract: The preparation of polymethylcyclosiloxane (PMCS) is described. PMCS may be used as a resist in which siliceous film patterns may be formed by irradiation with an electron beam. These siliceous patterns are readily developed and may be used directly in semiconductor technology as diffusion barriers or as etch-resistant layers, and after suitable heat treatment they may be used also as passivating layers. Transistors were made using PMCS film patterns defined by electron beams as diffusion barriers and as passivating layers. The sensitivity of PMCS to irradiation may be increased by controlled condensation to give a higher molecular weight polymer, or by introducing vinyl groups to replace some of the methyl groups in the polymer. The chemical changes which occur in PMCS upon irradiation by electrons were investigated and it is shown that at doses normally used in making film patterns of use in semiconductor technology, crosslinking occurs mainly through the hydroxyl groups present in the polymer. Subsequent treatment (thermal or radiation) can eliminate organic residues to produce a film which is identical to thermally grown silica.

Process for forming a resist mask

Abstract: A resist mask formation process in which a first layer of photoresist is applied to a substrate, blanket exposed to react the photoactive material in the resist and postbaked. A second layer of photoresist is then applied, exposed patternwise, and portions of the substrate are uncovered by solvent development of the resist layers.

Method of creating a replicating matrix

Abstract: A video disc master of glass, having a metal surface with microscopic apertures therein representing information, is coated with a commercial photosensitive resist, the sensitivity of which has been enhanced. The resist is uniformly exposed through the glass disc. The unexposed resist is removed using conventional developers to which a surfectant is added. The resulting disc has surface irregularities of predetermined height which can be alternatively used to product "stampers" for embossing replicas or to produce a mold for casting replicas.

Modified (meth)acrylate electron-resist. material - combine high dissolution capacity and sensitivity with reduced film thickness

Abstract: Electron resist materials consist of a linear (meth)acrylate polymer having 3-20C side-chains wich contain double-bonded end-gps. The materials have good adhesion, resistance to certain media, high dissoln. Capacity and high sensitivity at low film thicknesses for electron irradn.

Method for forming a resist mask using a positive electron resist

Abstract: Cathode ray-sensitive coating films known as positive type film which consist of a copolymer of methylmethacrylate with a member or comonomer selected from the group consisting of acrylonitrile, methacrylonitrile and maleic anhydride; these films are suitably used as a positive type photoresist, and as a memory medium for a high density memory.

Methods suitable for use in or in connection with the production of microelectronic devices

Abstract: A fabrication method suitable for use in or in connection with the production of a microelectronic device, which method is of the kind in which an electron beam which is accurately deflectable over a limited field is applied to change the nature of a layer of resist material on a substrate whereby parts of the layer of resist material may be selectively removed to form a predetermined pattern for the purpose of processing the substrate, includes providing on the layer of resist material a plurality of alignment marks so located on the layer that when the layer is in a desired position for exposure by the electron beam there is always at least one alignment mark belonging to the plurality in the field of accurate deflection of the electron beam, aligning the electron beam by reference to the alignment marks and selectively exposing the layer to the electron beam. The method may be that of producing a device mask suitable for subsequent use in the production of a microelectronic device or that of producing a microelectronic device itself.

Method for making the self-aligned gate contact of a semiconductor device

Abstract: A self-aligned gate contact of a semiconductor device is made without etching the semiconductor member during the gate contact forming step. A metal layer for forming contacts of the semiconductor device is deposited on a major surface of the semiconductor member and thereafter overlaid with a resist layer. A window pattern corresponding to the desired gate contact is formed in the resist layer, and the metal layer is undercut and removed adjacent the window pattern to expose portions of the major surface of the semiconductor member and to form overhanging portions of the resist layer adjacent the window pattern. Simultaneously with the undercutting, at least portions of contacts of the semiconductor device are formed in the metal layer. The desired gate contact is then self-aligned on the major surface by deposition through the window pattern in the resist layer. The method is particularly useful in making Schottky barrier gate field-effect transistors with high frequency capability, which requires minimal distance between source and drain contacts with an electrically separate Schottky barrier gate contact therebetween.

Process for simultaneous development and etch of photoresist and substrate

Abstract: Photoresists are developed and the supporting substrate is etched simultaneously therewith by bringing the resist (after exposure) into physical contact with a fluid containing a developer for the resist and an etchant for the supporting substrate.

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.

Photosensitive polymer composition

Abstract: Light-sensitive film forming polymers are disclosed which comprise recurring units of benzoate- and furoate-esterified polyvinyl alcohol as well as their utilization as photographic resist materials and printing plates for lithography

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.

IGFET Inverter Circuits made with Electron Lithography

Abstract: In IGFET circuitry, it has been predicted that halving the lateral dimensions should bring about approximately a fourfold speed advantage; providing doping levels, vertical dimensions, and applied voltages are constant. We have used electron lithography to make p-channel IGFET inverter circuits with 9- and 4-μ gates and have demonstrated a sixfold improvement in the propagation delay for smaller circuits. The devices were made using a refractory metal and ion implantation as described by Moline et al., and by Boll and Lynch. (IEDM, Washington, 1972). The electron resist (used for all four lithographic stages) was much more sensitive than polymethylmethacrylate.

Fabrication of Integrated CMOS Transistors using Electron Lithography and Ion Implantation

Abstract: Electron lithography and ion implantation have been used in the fabrication of integrated complementary P-channel and N-channel transistors. A digitally controlled single electron beam system, the Electron Micropattern Generator, aligned and exposed the eight mask levels required. The cumulative alignment tolerance was 3 μ. Fabricated devices had channel lengths of 1, 2, and 6 μ, and drain-source breakdown voltages of − 22 and + 12 V for the P- and N-type, respectively. Ion implantation was used to produce self-aligned gate structures by extending the diffused source and drain contact regions to the gate edges. The implantation masks consisted of 3000 A aluminum and 7700 A PMM resist. Boron and phosphorus ions were implanted at 50 and 100 keV, respectively at dosages ranging from 1×1014 to 1×1015 ions/cm2. Sintering and annealing operations were performed at 500 °C for 10 min in N2 atmosphere. Sheet resistances ranged from 2700 to 1000 Ω/□ for implanted boron and 700−240 Ω/□ for the phosphorus. Evolving h...

Apparatus for etch resist coating of plated holes in printed circuit boards

Abstract: Etch resist coating is applied into the plated holes in a printed circuit board by dipping the board in a liquid etch resist solution of farily low viscosity, squeezing the etch resist into the holes by pressing the board between opposed press rolls, followed by first squeegeeing the top and then the bottom of the board to wipe both surfaces. This results in a resistcoated hole.

Chemical fabrication of overhanging ledges and reflection gratings for surface wave devices

Abstract: A method is described of etching structures into α quartz and LiNbO 3 , two materials widely used in surface wave devices and which heretofore have not been found suitable for use with chemical etching techniques, in which concentrated HF acid at a predetermined temperature is used as an etchant, and the formation of overhanging ledges accomplished through a specific crystal orientation. Steps are shown which avoid the problems associated with suitable masking of the surface, which problems were encountered in the prior art, a primary step being one of a mechanical-chemical polishing to assure that the resist mask adheres to the surface properly.

Theory and Practice of MOS Processing Techniques-1973

Abstract: Current industrial practice and theory applicable to the fabrication of low-voltage p-channel metal-oxide-semiconductor (PMOS) devices is summarized. An extensive bibliography and design parameter graphs are presented.

Electron beam techniques for magnetic bubble device fabrication

Abstract: By using the electron beam machine to expose an electron sensitive resist and then by use of the 'float-off technique it is possible to produce the necessary permalloy overlay patterns for bubble devices with micron linewidths. Specification of the pattern is by computer program. At higher powers, the electron beam can also be used to damage the bubble material. This damage can be used to constrain the bubble motion.