Showing papers on "Photomask published in 1994"

Process for making an array of tapered photopolymerized waveguides

Abstract: The present invention is directed to a process for making an array of tapered photopolymerized waveguides. The tapered waveguides are useful as a display means in direct view devices and projection display devices. In step (a), a photomask is placed in substantial contact with a substrate wherein the photomask has opaque and transparent regions. In step (b), a substantially uniform thickness of photopolymerizable mixture is placed on the substrate so that the substrate is positioned between the photopolymerizable mixture and the photomask wherein (i) the photopolymerizable mixture comprises at least one reactive monomer and photoinitiator and (ii) the photoinitiator is present in an amount sufficent to form a gradient of substantially collimated actinic radiation across the thickness of the photopolymerizable mixture during subsequent step (c). In step (c), while maintaining the photopolymerizable mixture and substrate in a substantially fixed plane relative to the substantially collimated actinic radiation, the photopolymerisable mixture is exposed through the transparent regions of the photomask to the substantially collimated actinic radiation for a time sufficent to form an array of tapered photopolymerized waveguides wherein (i) the tapered end of each of the waveguides extends outward from the substrate, (ii) each of the waveguides has a light input surface adjacent the substrate and a light output surface distal from the light input surface, and (iii) the area of the light input surface of each of the waveguides is greater than the area of its light output surface. In step (d), the photomask and photopolymerizable mixture which was not substantially polymerized by the substantially collimated actinic radiation during step (c) are removed from the substrate.

Dry etching for coherent refractive microlens arrays

Abstract: Coherent arrays of refractive micro-optics are fabricated in the surface of silicon using a combination of lithographic and reactive-ion etching (RIE) techniques. The aspheric profile can be approximated in a stepwise manner by iterative steps of photolithography and RIE (binary optics technology), by direct etching of a preshaped polymer microlens etch mask into the substrate, or by analog etching of a lens profile directly into the substrate through a pinhole mask.

Method of forming a photomask for a printing plate with an ink jet

Abstract: A method and apparatus for preparing a printing plate without the need for a photomask formed from a sheet of photographic film bearing the positive or negative of the image to be printed. According to the invention, an ink jet print head deposits ink onto a light-sensitive emulsion in a pattern which corresponds to either the positive or negative of the image to be printed. The printed pattern provides a photomask for subsequent exposure of the emulsion.

Halftone phase shift photomask, halftone phase shift photomask blank, and methods of producing the same

Abstract: A halftone phase shift photomask designed so that it is possible to shorten the photoengraving process, use a production line for a conventional photomask, prevent lowering of the contract between the transparent and semitransparent regions at a long wavelength in the visible region, which is used for inspection and measurement, and also prevent charge-up during electron beam exposure, and that ordinary physical cleaning process can be used for the halftone phase shift photomask. The halftone phase shift photomask has on a transparent substrate (1) a region which is semitransparent to exposure light and a region which is transparent to the exposure light so that the phase difference between light passing through the transparent region and light passing through the semitransparent region is substantially π radians. A semitransparent film that constitutes the semitransparent region is arranged in the form of a multilayer film including layers (3, 4) of chromium or a chromium compound. For example, the layer (3) is formed of chromium oxide, chromium oxide nitride, chromium oxide carbide, or chromium oxide nitride carbide, and the layer (4) is formed of chromium or chromium nitride. The layer (3) mainly serves as a phase shift layer, while the layer (4) mainly serves as a transmittance control layer that suppresses the rise of transmittance at the long wavelength side. The semitransparent film is formed by physical vapor deposition.

New mask evaluation tool: the microlithography simulation microscope aerial image measurement system

Abstract: The Zeiss MSM100 microlithography simulation microscope can evaluate phase shift and conventional photolithographic masks. In this paper we discuss the MSM design, its operation, image capture and analysis methods, and typical applications. The tool's unique optical system captures `through focus' images of a mask for a selected NA, sigma, and wavelength, thus paralleling the characteristics of a particular optical stepper. The MSM operates at i-line (365 nm) and DUV (248 nm) wavelengths, and handles commonly used 5 or 6 inch reticles. The images obtained are optically equivalent to that incident on resist, but are highly magnified so that they may be recorded using a DUV CCD camera. Typically, features of interest are recorded as a through focus series; image intensity is digitized. Application to the assessment of defect printability, both before and after repair, is presented. Masks have been analyzed to predicted CD values which are in good agreement with subsequent resist work. Unconventional illumination schemes have been studied.

Method of chromeless phase shift mask fabrication suitable for auto-cad layout

Abstract: A method for forming chromeless phase shifting photomasks is provided. The photomasks include a transparent substrate and raised phase shifters formed with a vertical edge and a tapered edge. During a lithographic process using the photomask, the vertical edges of the phase shifters form nulls on a photoresist covered wafer. The tapered edge prevents the formation of undesirable stringers on the wafer. The method of the invention includes the steps of: forming an opaque etch mask including a pattern of opaque features on a transparent substrate; forming a layer of resist over one sidewall of each opaque feature; and then etching the photoresist with one etching species and the substrate with another etching species to form chromeless phase shifters each having a vertical edge and a tapered edge.

Photomask and method of forming resist pattern using the same

Abstract: A photomask for use in forming a photoresist pattern by projection exposure, comprising opaque stripes respectively arranged on a mask substrate at a given pitch and phase shifters formed alternately on light-transmissive areas between said opaque stripes. The widths of the opaque stripes are larger than those of said light-transmissive areas whereby the edges of said phase shifters on said light-transmissive areas are prevented from being transferred to a wafer.

Photomask for t-gate formation and process for fabricating the same

Abstract: The present invention relates to a photomask for forming a T-shaped gate structure on a high speed FET through a photolithography, comprising opaque layer patterns 2 and 2a for defining a head portion of the T-shaped gate structure and half-tone layer patterns 3 and 3a for defining a foot portion thereof. The half-tone film patterns composed of a chrome layer are deposited to a thickness thinner than that of the opaque layer patterns so that the half-tone layer patterns show a relatively lower transmittance to an incident beam. The application of the photomask of the invention to the process for forming a T-shaped gate structure improves process reproducibility and leads to great cost savings.

Blanks for halftone phase shift photomasks, halftone phase shift photomasks, and methods for fabricating them

Abstract: The invention relates a halftone phase shift photomask and a blank therefor, which enables the transmittance of a phase shift portion to be varied even after blank or photomask fabrication, can accommodate to a variety of patterns, and can be fabricated on a mass scale. The exposure light transmittance of a halftone phase shift layer is arbitrarily variable within the range of 1% to 50%, inclusive, by exposing the blank or photomask to a high temperature elevated to at least 150° C., to an oxidizing atmosphere, or to a reducing atmosphere at a step that can provided independent of the steps for film-forming or photomask fabrication step. This enables the exposure light transmittance of the halftone phase shift layer to be changed to any desired value after blank or photomask fabrication, and so an optimal halftone phase shift photomask to be obtained depending on the size, area, location, shape, and the like of the transferred pattern.

Attenuated phase-shifting photomasks fabricated from Cr-based embedded shifter blanks

Abstract: I-line (365 nm) and G-line (436 nm) attenuated phase shifting photomasks have been developed using single layer Crbased photoblanks. The absorber layer has a composition gradient that allows the desired transmission to be tuned while maintaining control over reflectivity and phase shift. These photoblanks are manufactured in existing facilities, and masks are processed much like conventional opaque Cr-based materials. They can be inspected and repaired on current equipment with slight modifications. Printing has been demonstrated on current generation steppers. Deep UV extendability of these materials is also being studied, with a 5% Deep UV (248 nm) single layer photoblank chemistry already demonstrated.

Method of fabricating a display device

Abstract: An object of the technology of our invention is to solve a luminance defect viewed as a "seam" or the like and to provide a liquid crystal display device having a screen for equally displaying an image. For example, when an exposing process is performed for one conductor layer or a dielectric layer, a total of four photomasks are used corresponding to four shot areas. A light insulation layer of a photomask used for the exposing process for patterning for example a signal line is formed so that it becomes a projection pattern of the signal line. The photomasks corresponding to adjacent shot areas are formed so that patterns of the light insulation layers of the boundary portion are engaged with each other on the plane.

Photomask substrate plate of synthetic fused silica glass for photolithography

Abstract: A photomask substrate plate of synthetic fused silica glass for use in photolithography can be imparted with remarkably improved stability relative to the transmissivity to ultraviolet light and to the dimensional changes due to so-called "radiation compaction" under irradiation, in particular, with ultraviolet light of short wavelength, such as the light emitted from an ArF excimer laser, when the content of molecular hydrogen in the fused silica glass is in the range from 1×10¹⁷ to 1×10¹⁹ molecules/cm³. The content of molecular hydrogen can be controlled within the specified range by suitably selecting the conditions used in the preparation of silicon dioxide by the direct flame hydrolysis method and the annealing treatment.

Comprehensive evaluation of major phase-shift mask technologies for isolated gate structures in logic designs

Abstract: This paper presents a comparative analysis of binary `chrome-on-glass,' attenuated, biased rim, and phase edge shifted DUV lithography solutions for advanced circuitry in the sub-250 nm image size regime. Lithography techniques are compared based on design complexity, ground rule impact, process latitude, and cost. Data are presented from aerial image simulations (SPLAT), aerial image measurements (AIMSR), and SEM measurements. Phase edge shifted designs clearly exhibit the largest process window for 200 nm linewidths exposed on a 0.5 NA 248 nm DUV stepper. The complexity of the mask engineering (design as well as manufacture) and exposure process for this `hard' phase shifting technique warrants the study of less powerful but also less restrictive phase shifting options. This paper investigates the tradeoffs associated with various applicable phase shift mask (PSM) techniques and presents recommendations based on specific program requirements.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Application of an aerial image measurement system to mask fabrication and analysis

Abstract: Application of an Aerial Image Measurement System (AIMSTM) to binary and phase- shift mask fabrication and evaluation is described. The AIMS tool, an optical system which measures the aerial image directly from a mask, provides rapid feedback on lithographic performance for a variety of stepper configurations through modifications of the wavelength, numerical aperture, and illuminator design. The AIMS tool has been applied during the implementation of an alternating phase-shift mask (PSM) fabrication process in order to understand the impact of the etched-quartz sidewall on lithographic performance. AIMS measurements were used to extract the effective phase and transmission as a function of phase- etch depth as well as post-etch treatment condition. A set of basic test structures are proposed which can be used in conjunction with the AIMS tool to automate the extraction of transmission, phase, and second-level overlay for phase-shifting processes such as alternating and attenuating PSM.

Formation of fine pattern

Abstract: PURPOSE:To efficiently produce fine patterns continuously changing in height. CONSTITUTION:Light transmissive parts or light shielding parts are separated to a plurality at the time of forming prescribed patterns on a photoresist 6. A photomask formed by making the ratio of the areas of the light parts or light shielding parts correspondent to a change in the heights of the patterns is used. An exposure distribution is applied to the photoresist 6 by exposing the photoresist 6 via this photomask, by which such patterns as to have the varying heights to a substrate 1 are formed on the photoresist 6.

Attenuated phase-shifting mask with a single-layer absorptive shifter of CrO, CrON, MoSiO, and MoSiON film

Abstract: Attenuated phase-shifting mask with a single-layer absorptive shifter of CrO, CrON, MoSiO or MoSiON films has been developed. The optical parameter of these films can be controlled by the condition of sputtering deposition. These films satisfy the shifter requirements, both the 180-degrees phase shift and the transmittance between 5 and 20% for i-line. MoSiO and MoSiON films also satisfy the requirement for KrF excimer laser light. Conventional mask processes, such as etching, cleaning, defect inspection and defect repair, can be used for the mask fabrication. Defect-free masks for hole layers of 64 M-bit DRAM are obtained. Using this mask, the focus depth of 0.35-micrometers hole is improved from 0.6 micrometers to 1.5 micrometers for i-line lithography. The printing of 0.2-micrometers hole patterns is achieved by the combination of this mask and KrF excimer laser lithography.

Photomask, production of photomask, exposure method and production of semiconductor device

Abstract: PURPOSE:To obtain the optimum condition by combining one of the parameters with plural data in the other preset two ranges and obtaining the allowable range in the combination to find out the correlation of the combinations. CONSTITUTION:One among the defocus tolerance, mask pattern size tolerance II and exposure tolerance I is combined with plural data in the other preset two ranges, and the allowable range III is obtained from the combinations to determine the optimum value. As a result, the correlation of many parameters, e.g. 3, is found out, and the optimum condition is obtained from the correlation. Consequently, the departure from the actual condition is reduced, various performances are quantitatively seized, and the time and cost are reduced. Further, the effect of the variance in the mask pattern size, etc., can be considered, and actual optimization is made possible.

Production of phase-shift photomask blank, phase-shift photomask blank and phase-shift photomask

Abstract: PURPOSE: To provide a phase-shift photomask blank suitable to UV exposure and highly resistant to chemicals. CONSTITUTION: Gaseous nitrogen monoxide is added by 2.65-6vol.%, then a molybdenum silicide target is sputtered, and a molybdenum silicide oxynitride film is formed on a transparent substrate. This film is suitable to the phase-shift film in a KrF excimer laser wavelength and highly resistant to chemicals. Since the chemical resistance is especially improved when the proportion of the gaseoous nitrogen monoxide is low, the film is used as the protective film of the phase-shift film by adding 0.5-6vol.%. The process variation of the transmittance is reduced when the film is heat-treated at >=200 deg.C, and the transmittance is increased in the exposure wavelength.

Manufacturing of half-tone phase-shift masks I: blank

Abstract: Half-tone phase shift mask (HT-PSM) blanks for i-line (365 nm) and g-line (436 nm) lithography, using chromium composites as a half-tone shifter, are brought into production. A bilayer structure of a 10 - 20 nm thick opaque, conductive chrome layer and a phase-shifting CrON layer is proposed, which can be formed by continuous deposition of the two layers and etched continuously by the process similar to that of the conventional chrome photomask. It shows low visible light transmission of less than 30% so that it can be inspected, and also shows enough conductivity to decay the excess charge during electron beam writing. HT- PSMs made of these blanks can be cleaned by sulfuric acid at 100 degree(s)C and can be used at least up to an irradiation of 1 MJ/cm2, when used for i-line exposure. The specification for the transmission is (target +/- 1)% for any point on any plate, and 0.7% range for any point on one plate, where the target ranges from 6% to 10%. The specification for the phase shift is currently (180+/- 10) degree(s).© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Solid-state image-pickup device

Abstract: PROBLEM TO BE SOLVED: To provide a solid-state image-pickup device, the potential of the readout gate of which is set by optimally solving troubles due to misalignment of a mask pattern at forming of the readout gate. SOLUTION: For manufacturing a solid-state image-pickup device, a readout gate 15 is formed together with a photosensor 14 by simultaneous injection of an impurity through the use of a step of impurity injection for improving the transmission efficiencies of a vertical CCD(charge-coupled device) register 13. In this way, the potential of the readout gate 15 under gate electrode is set optimally, without being affected by misalignment of a photomask.

Halftone phase shift photomask comprising a single layer of halftone light blocking and phase shifting

Abstract: The invention provides a halftone phase shift photomask that is of much more simplified structure and so can be fabricated much more easily, which comprises a transparent substrate 10 and a single halftone light-blocking and phase shift layer 11 that is formed on the surface thereof according to a predetermined pattern and is made up of a material of homogeneous composition, characterized in that: said single halftone light-blocking and phase shift layer has a film thickness d that is virtually equal to a value defined by d=λ/{2(n-1)} where λ is the wavelength at which the photomask is used, and n is the index of refraction of the single layer, or that is an odd-numbered multiple of said value, and has a transmittance lying substantially in the range of 5 to 30%. The layer 11 may be made up of any of CrO x , CrN x , CrO x N y and CrO x N y C z .

Method of producing photomask and exposing

Abstract: A photomask, a method of producing the same, a method of exposing using the same and a method of manufacturing a semiconductor device using the same are disclosed, which permit correlation to be found out with respect to a large number of mask condition parameters, thus permitting optimum condition to be obtained such as to be less aloof from the actual process, permits quantitative grasping of performance, permits reduction of time and cost, and permits effects of mask pattern size fluctuations, etc. into considerations. Either defocus latitude, mask pattern size latitude II and exposure latitude I is combined with pluralities of data in predetermined ranges of the other two latitudes I and II to determine the permissible range of the first-noted latitude III for optimum value determination.

Patterned deposition of thin films

Abstract: A method for creating a patterned thin film of a high surface energy material on a substrate comprising the steps of creating a photomask pattern on the substrate using photolithography, providing an oppositely charged surface on the substrate and photomask, if such does not exist, from that of particles of the high surface energy material, removing the photomask and exposing the substrate to an aqueous colloidal suspension of particles composed of the high surface energy material to adsorb seed particles onto the surface of the substrate, or removing the photomask after adsorbing seed particles to the surface, and then depositing a uniform thin film of the high surface energy material by chemical vapor deposition onto the seeded substrate.

Photomask for semiconductor integrated circuit device

Abstract: In making semiconductor patterns on a glass substrate by a light shielding substance such as chromium (Cr), the amount of necessary data and time to make the semiconductor patterns can be reduced. Patterns each having a size smaller in at least one direction than the resolution limit of an exposure device are previously arranged on the glass substrate at regular intervals smaller than the resolution limit and they are partially removed in accordance with the patterns for a semiconductor integrated circuit. Thus, a photomask can be provided for the semiconductor integrated circuit.

Impact of attenuated mask topography on lithographic performance

Abstract: Experimental evaluations were used in conjunction with rigorous electromagnetic simulations to evaluate the affect of attenuated phase-shifting mask (PSM) fabrication processes on lithographic performance. Three attenuated PSMs were fabricated including a normal leaky- chrome reticle and two novel approaches: a recessed leaky-chrome reticle for reduction of edge scattering and a single-layer reticle employing a hydrogenated amorphous carbon film. Direct aerial image measurements with the Aerial Image Measurement System (AIMSTM), exposures on an SVGL Micrascan 92 deep-UV stepper, and TEMPEST simulations were used to explore the effects of edge-scattering phenomena for the different mask topographies. For each reticle, the process window at a feature size of 0.25 micrometers was evaluated for four basic feature types: nested lines, isolated lines, isolated spaces, and contact holes. Further evaluation of the sidewall profiles and the image size on the mask are required to address these discrepancies.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Photomask inspecting method and apparatus

Abstract: In a photomask inspecting method, a photomask is inspected on the basis of the difference between the polarized state of elliptical light produced upon superposition of two linearly polarized light beams having orthogonal polarization directions and passing through two different optical paths and the polarized state of elliptical light produced when two linearly polarized light beams are superposed on each other after a target portion of a photomask is set in the optical path of one of the linearly polarized light beams. A photomask inspecting apparatus is also disclosed.

Embedded phase shifting photomasks and method for manufacturing same

Abstract: The present invention phase shifting photomask is fabricated by means of a structured modification to the surface of a mask blank suitable for photolithography. Ion implantation, diffusion or similar processes are used to alter the optical properties of selected areas of a mask blank in such a way that these areas modify the intensity and phase of optical radiation transmitted through the processed areas of the mask blank substrate. The present invention provides the intended phase and intensity modulation by modification of a surface layer or other layer which is close to the surface of the mask blank. This leaves the actual surface of the mask blank intact and smooth without chemical changes to the surface of the mask blank. In this way optical radiation is not scattered on the borders of different materials and unwanted particulates will have a lower chance of adhering to a smooth surface with little or no topography. Use of photomasks manufactured in accordance with the present invention method enhances the resolution and process window, for example, depth of focus and/or exposure latitude of the lithographic process.

Photomask having patterns to reduce power of a stepper

Abstract: An energy-saving photomask comprises: at least one first pattern region in which a light can penetrate through the photomask without diffraction; and a second pattern region in which a plurality of fine patterns are formed in such a way to serve as slits through which the light is diffracted to increase the energy of the light irradiated relative to the first pattern region and diffracted to an extent that it comes to have an insufficient energy for the development of all photosensitive film except below the first pattern region. By virtue of the auxiliary patterns, the energy of the light incident on the photosensitive film can be rich at the auxiliary patterns contributes intensity of light to the desired portions without seriously affecting other portions. Because of a reduction of processing time, the photomask prolongs the lifetime of a light lamp in the stepper, as well as allows usage of a stepper with low power.

Method for forming a photomask pattern

Abstract: A silicon film is formed on the surface of a substrate for a photomask, and a silicon nitride film is formed thereon. Then the silicon film and the silicon nitride film are patterned into desired shapes by photolithography method, the edge portion of the patterned silicon film is oxidized to provide a translucent region consisting of a silicon oxide film only on the edge portion, and the silicon nitride film is removed.

Exposure device and its method

Abstract: PURPOSE:To perform the exposure of a large-size substrate with high accuracy and high throughput by dividing a pattern formed in the substrate and moving the divided region relatively to the photomask of the substrate so that the divided region is located in the mask region of the photomask CONSTITUTION:A pattern formed in a substrate is divided into 1/2 to 1/4 The divided regions are symmetrical to a line or a point to each other At first, a substrate 2 is moved relatively to a photomask 10 so that the first divided region of the exposure regions of the transparent substrate 2 is located in the mask region of the photomask The light from a light source for exposure is applied to the first divided region through the photomask 10 to perform the exposure of the first divided region