Showing papers on "Lithography published in 1982"

Improving resolution in photolithography with a phase-shifting mask

Abstract: The phase-shifting mask consists of a normal transmission mask that has been coated with a transparent layer patterned to ensure that the optical phases of nearest apertures are opposite. Destructive interference between waves from adjacent apertures cancels some diffraction effects and increases the spatial resolution with which such patterns can be projected. A simple theory predicts a near doubling of resolution for illumination with partial incoherence σ < 0.3, and substantial improvements in resolution for σ < 0.7. Initial results obtained with a phase-shifting mask patterned with typical device structures by electron-beam lithography and exposed using a Mann 4800 10X tool reveals a 40-percent increase in usuable resolution with some structures printed at a resolution of 1000 lines/mm. Phase-shifting mask structures can be used to facilitate proximity printing with larger gaps between mask and wafer. Theory indicates that the increase in resolution is accompanied by a minimal decrease in depth of focus. Thus the phase-shifting mask may be the most desirable device for enhancing optical lithography resolution in the VLSI/VHSIC era.

Production of separation-nozzle systems for uranium enrichment by a combination of X-ray lithography and galvanoplastics

Abstract: X-ray lithography using synchrotron radiation has been applied in a multi-step process for the production of plastic moulds to be used in the fabrication of separation nozzles by electrodeposition. For characteristic dimensions of a few microns a total height of the nozzle structure of about 400 μm has been achieved. Structural details of about 0.1 μm are being reproduced across the total thickness of the polymer layer. The surface finish of metallic separation nozzles produced by electrodeposition was equivalent to the high quality of the polymer surface. The separation-nozzle systems fabricated by the described method allow an increase by a factor three of the gas pressure in separationnozzle plants as compared to the present standard. This results in considerable savings in the enrichment of 235U for nuclear power production.

Blazed gratings and Fresnel lenses fabricated by electron-beam lithography

Abstract: A blazing technique using electron-beam lithography to achieve higher efficiency of gratings and Fresnel lenses is described. Transmission-type blazed gratings have been formed in polymethyl methacrylate films. As a result of measurement, we found that their diffraction efficiency of the first order in these gratings amounts to as much as 60 to 70% at 0.633 microm. Fresnel lenses of 1-mm diameter and 5-mm focal length, which have a sawtooth relief profile, have been also fabricated, and the experimental results showed high-efficiency performance (about 50%) and nearly diffraction-limited focusing.

Use of selective annealing for growing very large grain silicon on insulator films

Abstract: The selective annealing technique (laser annealing under a patterned antireflecting coating) has been successfully applied to the growth of very large (20×400 μm) silicon single crystals on SiO2. The grain boundary location is controlled by a conventional lithography step, and the grains obtained have a nearly perfect rectangular shape.

Ultrafast deep UV Lithography with excimer lasers

Abstract: The use of high-power pulsed excimer lasers for photolithography is described for the first time. Short exposure times, high resolution and absence of speckle are experimentally demonstrated. Using a XeCl laser at 308 nm and a KrF laser at 248 nm, excellent quality images are obtained by contact printing in two positive photoresists. Resolution down to 1000 line-pairs/mm is demonstrated. These images are comparable to state-of-the-art lithography done with conventional lamps; the major difference is that the excimer laser technique is ∼ 2 orders of magnitude faster. Preliminary results on reciprocity behavior in several resists are also presented.

Evaluation of the gas puff z pinch as an x‐ray lithography and microscopy source

Abstract: Soft x rays (100–10 000 eV), due to their short wavelength (0.1–10 nm) can play an important role in high resolution microscopy and lithography. The gas puff Z pinch is an intense source of soft x rays. Calorimeter and x ray diode measurements showed that 10% of the stored electrical energy was converted to radiation in the range of 1–10 nm. Commercial photoresist polymethyl methacrylate (PMMA) and some new resists—CR 39, nitrocellulose, were exposed to the pinch radiation. The developed images on the resists have been studied with a scanning electron microscope. The resolution was found to be source limited, but a simple modification can improve the resolution by more than an order of magnitude.

Ultrafast high-resolution contact lithography with excimer lasers

Abstract: A new technique for speckle-free, fine-line high-speed lithography using high-power pulsed excimer lasers is described and demonstrated. Use of stimulated Raman shifting is proposed for obtaining the most desirable set of spectral lines for any resist. This permits, for the first time, the optimization of the exposur wavelengths for a given resist, rather than the reverse situation. Excellent-quality images are obtained in 1-µm-thick diazo-type photoresists such as ® AZ-2400 and a diazonaph-thoquinone-®Novolak resist system by means of contact printing with a XeCl laser at 308 nm and a KrF laser at 248 nm. Resolution down to 1000 line pairs per millimeter is experimentally demonstrated. These images are comparable to state-of-the-art contact lithography obtained with conventional lamps. The major difference is that the excimer laser technique is approximately two orders of magnitude faster. Tests on reciprocity failure ins everal resists indicate a decrease in sensitivity by only a factor of three, despite the ≅108 times larger power density used in the laser exposures. The possibility of photochemical reactions being diflerent from those taking place in the case of lamp exposures is discussed in view of these results.

Deep uv submicron lithography by using a pulsed high-power excimer laser

Abstract: Deep uv lithography by using a pulsed high‐power excimer laser is demonstrated, in which submicron patterns with high resolutions were fabricated on PMMA (polymethyle methacrylate) photoresists by laser irradiation for 20 ns.

Electron-beam proximity printing: a new high-speed lithography method for submicron structures

Abstract: A laboratory prototype of an electron-beam proximity printer is described which shadow-projects patterns of chip-size transmission masks onto wafers. Electron-beam transmission masks with physical holes at transparent areas have been fabricated with the smallest structures down to 0.3 µm. Experiments to replicate mask patterns were directed at demonstrating the applicability of this lithographic method to high-speed printing of repetitive patterns on wafers. Linewidth resolution and positional accuracy, as well as exposure speed, meet the requirements for micron and submicron lithography.

Mask structure for X-ray lithography and method for manufacturing the same

Abstract: The invention provides a mask structure for X-ray lithography, having a mask substrate of an X-ray transmitting material, a mask pattern of an X-ray absorbing material which is formed on the surface of the mask substrate or therein, a support ring for supporting the rear periphery of the mask substrate, and a lattice-shaped metal film embedded in a lattice-shaped slit in the mask substrate. The mask structure with a large area has a dimensional stability.

Supports for lithographic printing plates and process for producing the same

Abstract: A support for a lithographic plate and process for producing a support for such a plate are described, which process comprises: mechanically roughening the surface of an aluminum plate, chemically etching about 5 to 20 g/m2 of aluminum from the surface of the plate, and applying an alternating wave-form electric current to the plate in an acidic aqueous solution such that the quantity of electricity generated with the plate as the anode is equal to or greater than the quantity of electricity generated with the plate as the cathode, electrolysis being carried out such that the current density when the plate is the anode is not less than about 20 A/dm2 and the quantity of electricity generated with the plate as the anode is about 200 coulombs/dm2 or less.

Ultra‐small metal particle arrays produced by high resolution electron‐beam lithography

Abstract: Arrays of silver and gold‐palladium particles smaller than 10 nm in diameter and center‐to‐center spacings as low as 25 nm have been fabricated by electron‐beam contamination lithography in a scanning transmission electron microscope and ion milling.

New inorganic electron resist system for high resolution lithography

Abstract: A new Ag2S/As2S3 negative electron resist system is proposed for nanostructure fabrication. Linear gaps down to 30 nm wide have already been resolved. Sensitization of the Ag2S3 with a chemically deposited layer of Ag2S overcomes the limitations involved in the use of silver halides as a source of silver. Although the sensitivity of this resist is very low (4×10−3–10−2 C/cm2) its extremely high contrast (γ>5.5) is an advantage in nanostructure fabrication where it is necessary to discriminate against exposure by backscattered electrons.

Electron sources and equipment having electron sources

Abstract: An electron source having a rapid response time comprises at least one n-p-n structure (and possibly an array of said n-p-n structure) formed in a silicon or other semiconductor body (10) by a p-type first region (1) between n-type second and third regions (2 and 3). Electrons (24) are generated in the n-p-n structure (2,1,3) for emission into free space (20) from a surface area (4) of the body (10) after flowing from the second region (2) through the first and third regions (1 and 3). The n-p-n structure (2,1,3) has electrode connections (12 and 13) only to the n-type second and third regions (2 and 3). The first region (1) provides a barrier region restricting the flow of electrons from the second region (2) to the third region (3) until a potential difference (V) is applied between the electrode connections (12 and 13) to bias the third region (3) positive with respect to the second region (2) and to establish a supply of hot electrons (24) injected into the third region (3) with sufficient energy to overcome the potential barrier present between the surface area (4) and free space (20). The barrier region (1) forms depletion layers with both the n-type second and third regions (2 and b 3) and is depleted of holes by the merging together of these depletion layers at least when the potential difference (V) is applied to establish said supply of hot electrons (24). The n-p-n structure can be provided in a mesa portion (9) of the body (10) at a window in an insulating layer (11) so as to form a compact arrangement having very low associated capacitances. The electron sources may be used in cathode-ray tubes, display devices and even electron lithography equipment.

Multiple printing mode printing machine system

Abstract: To permit, selectively, lithographic printing, flexo printing, or direct lithographic printing on a printing machine with the same direction of rotation of the respective cylinders, a liquid application system (11) including a liquid application roller (15) is selectively positionable for engagement either with a plate cylinder (4, 5) of a lithographic system, the rubber blanket cylinder (2, 3) for direct lithographic printing, the plate cylinder then acting as a form ink transfer cylinder which is being continuously inked; or for engagement with the blanket cylinder, with a flexo printing plate applied to the blanket cylinder, and the plate cylinder being placed out of engagement with the blanket cylinder, the damping liquid for lithographic printing being replaced by flexo-printing ink, and the position (FIG. 3) being as close to the printing or impression line as possible, and between the zone of operation of the plate cylinder (4) and the printing cylinder (2) to prevent drying of the quick-drying flexo-printing ink.

Sub-50-nm lithography in amorphous Se-Ge inorganic resist by electron beam exposure

Abstract: Ag2Se/Se90Ge10 inorganic resist has been used to produce sub‐50‐nm lines by electron beam lithography. 35–50‐nm‐wide lines have been defined by wet chemical processing in 70‐nm‐thick Se‐Ge resist supported on a 50‐nm silicon nitride membrane. The effects of different chemical etchants on resolution are described.

X-Ray mask

Abstract: An improved X-ray lithography mask has been fabricated by forming an X-ray absorbing lithography pattern on a supporting foil of hydrogenated amorphous carbon. The substrate foil is formed by depositing a carbon film in the presence of hydrogen onto a surface having a temperature below 375° C. The hydrogen concentration is maintained sufficiently high that the resulting film has at least one atom percent of hydrogen. A film having about 20 atom percent of hydrogen is preferred. While impurities are permitted, impurities must be maintained at a level such that the optical bandgap of the resulting film is at least one electron volt. A film with an optical bandgap of about 2 electron volts is preferred.

Rotary printing machine system with optional continuous web printing

Abstract: To permit, selectively, continuous printing, for example for wallpaper, wrapping or gift wrap paper, plastic or other foils continuously coated wth adhesive or the like, while additionally permitting use of the machine for printing on substrates, such as paper, which have margins, the plate cylinders, or the web between the plate cylinders can be respectively so aligned or offset with respect to each other that the position of a groove (5, 6) on one plate cylinder, which would result in an unprinted strip of paper, can have printing information, or adhesive or the like applied thereto by a plate on another printing station or, selectively, the other printing station may have its plate adjusted to provide printing information in a second color over the printed information applied by the first plate cylinder. The system can be expanded with multiple cylinders, and may be applied to offset, direct lithographic, raised letter, flexo graphic printing, and the like. For continuous printing, two printing cylinders, preferably adjacent printing cylinder will have the same color ink applied thereto, overlap or adjustment being possible to thereby provide, for example, striped patterns of greater color intensity; multiple printing stations can apply patterns of different colors. The relative adjustment of the printing cylinders can be by way of a clutch (FIGS. 5, 6) or by adjustment of the length of the travel of the web between adjacent printing stations, by web length or register control rollers.

Deep-ultraviolet spatial-period division using an excimer laser.

Abstract: We have used the deep-UV output from an ArF laser and a grating mask with 199-nm spatial period to fabricate a 99.5-nm-period grating pattern in polymethyl methacrylate resist by spatial-period division. For sub 100 nm, lithography of periodic and quasi-periodic patterns (including Fresnel zone plates) by spatial-period division, deep-UV radiation offers a number of advantages over soft x rays.

SiN membrane masks for x‐ray lithography

Abstract: The fabrication and properties of a new x‐ray lithography mask are described. The mask is made of a plasma enhanced chemical vapor deposited (PCVD) silicon nitride (SiN) membrane, which is supported by a silicon frame. The PCVD SiN film, deposited on silicon substrate under appropriate conditions, has a tensile stress of about 1×108 dyn/cm2, which is much lower than that of a Si3N4 film prepared by conventional (pyrolytic) CVD. The strength of the PCVD SiN membrane, stretched over a silicon frame, is as high as that of a Si3N4/SiO2/Si3N4 sandwich structure membrane, and is much higher than that of a conventional CVD Si3N4 membrane. The PCVD SiN film with low stress realizes a low distortion x‐ray mask substrate which is expected to be applied to very fine pattern lithography.

0.15 &#181;m Channel-length MOSFET's fabricated using e-beam lithography

Abstract: We have fabricated MOSFET's with channel lengths as short as 0.1 µm by a modified NMOS process. The devices have been designed according to parameters obtained from numerical simulation. Electron-beam lithography has been used to define patterns at all levels with the negative resist GMC in a tri-level configuration. Heat treatments have been as short as possible to preserve very shallow source-drain junction depths ( L = 0.14 µm, we obtain g_{m} = 180 mS/mm for a gate oxide thickness of 160A.

Method for producing an aluminum support useful for lithography

Abstract: An improved substrate suitable for use as a base for a lithographic printing plate, especially a plate useful for the production of continuous tone images. The substrate is produced by extremely uniformly graining an aluminum sheet which has a highly polished, mirror-like surface.

Transparent X-Ray Lithography Masks

Abstract: With a view to producing a rigid and optically-transparent mask for use in X-ray lithography, the membrane strength was theoretically analyzed as a function of the residual stress in films. In silicon nitride films, reduction of the residual stress resulted in an increase in membrane strength accompanied by a decrease in optical Transparency. Silicon nitride film was then combined with transparent silicon dioxide film and an Si3N4/SiO2/Si3N4 sandwich-structure membrane was developed. In this membrane, the compressive film force approached the tensile film force closely, keeping the membrane under tension. This produced an optically-transparent, rigid, smoothly stretched-out membrane. An X-ray lithography mask with 0.8 µm thick gold absorber patterns on this membrane was successfully used for four-level multiple-pattern replications using an optical auto-alignment system.

Multi-layer resist systems as a means to submicron optical lithography

Abstract: Multi-layer resist (MLR) systems improve resolution, aspect ratio, linewidth control, and sensitivity beyond what can be achieved by 1-layer systems. Therefore they have found applications in optical, e-beam, x-ray and ion beam lithography. The main reason for their impressive performance is that the imaging and the planarization functions of a photoresist are now separated. As shown in Fig. 1, a thick resist layer is used to planarize over topography, so that a thin imaging resist layer can be uniformly coated. After the top layer is delineated, it is used as a blanket exposure mask or etch mask to delineate the planarizing layer. Because this mask always conforms to the planarizing layer and is portable with the wafer, it is called a portable conformable mask (PCM). In a 3-layer system, the imaging and masking functions are further separated. A middle layer, generally inorganic, is used as the blanket exposure PCM or etch PCM.

Boron nitride X-ray masks with controlled stress

Abstract: It has been found that stress in X-ray transparent films used to form masks for X-ray lithography also cause distortions of the film and of the high-resolution X-ray-absorptive pattern formed thereon. A method is disclosed which anneals boron nitride films for use in X-ray masks in such a way as to control stress.

Linewidth control using anti-reflective coating for optical lithography

Abstract: Several types of anti-reflective (AR) coating, including TiW, V, polysilicon films, and spun-on layer incorporated with an absorbing dye have been investigated to eliminate the light reflection from layers under resist. The exposure latitude can be widely extended by the AR coating. Both the standing wave effect and the linewidth change with respect to variation in exposure dose can also be reduced significantly. This simple and convenient technique can be effectively applied to reduce linewidth variations at step cross-over for wafers with vertical aluminum steps less than 0.8 µm height.

Multilevel Ge-Se Film Based Resist Systems

Abstract: Multilevel resist systems based on Ge-Se films make possible the use of optical projection printers for printing 0.5-1.0μm features. The four multilevel resist systems considered employ either a photosensitive or a photopassive polymer layer for planarization. In bilevel schemes the surface of the Ge-Se film is reacted in a Ag(CN)i- containing solution to form a Ag2Se imaging layer. No reacted Ge-Se is used as a sacrificial layer in trilevel schemes. Ge-Se films are resistant to attack by oxygen plasma and therefore make good masks for pattern transfer by dry (reactive ion) etching, to a thick underlying photopassive polymer layer. Because of their high absorbance (a 105cm-1) in the ultraviolet and violet, Ge-Se patterns can also be used as exposure masks for transferring images to a thick underlying photosensitive polymer layer. The latter is "flood" exposed through the Ge-Se mask and wet developed. Both dry and wet processes provide steep wall-profile patterns in the polymer layer. The dry process provides superior feature size control while the wet process offers reduced processing cost. The exceptional lithographic performance exhibited by Ge-Se resist systems is attributed to a unique edge-sharpening effect; diffraction is compensated for by lateral silver diffusion in the Ag2Se layer. Patterns having 0.6μm lines and spaces are obtained over lcmXlcm fields with a defocus tolerance of 2.5μm using a standard Zeiss 10:1 reduction lens (N.A.=0.28, λ=436nm). Results indicate that optical lithography can practically print features in the size regime previously reserved for a-beam or x-ray based lithographic technologies.© (1982) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Substrate-tube lithography for optical fibres

Abstract: We describe the first use of substrate-tube lithography to build complex structures into MCVD fibre preforms. While the basic process is illustrated with high-birefringence fibres of 1.9 and 3 mm beat lengths and a two-core fibre, the technique is more general and may lead to a new class of integrated optical devices.