Showing papers on "Photomask published in 1993"

Optical exposure method

Abstract: An optical exposure method in photolithography applied for precise processing when semiconductor devices are produced. A pattern on a photomask is projected and exposed on a register on a base plate with an exposure device including a deformation illumination system, a photomask and a projection lens. The deformation illumination system is composed of a light source, a diaphragm and a condenser lens, and the diaphragm is provided with a linear through-hole. The optical exposure method uses a ray of linear light for illumination or two rays of linear light for illumination that are parallel with the pattern. The two rays of linear light are symmetrical with respect to an optical axis. These rays are parallel with the pattern in a position separate from the optical axis of the exposure device when the photomask pattern is a line and space pattern.

Fabrication of 0.1-um T-shaped gates by phase-shifting optical lithography

Abstract: We have developed a method for patterning sub-micrometer gates with T-shaped cross sections, which may be applied to manufacture high performance field effect transistors (FETs). The technique employs two exposures at the KrF excimer laser wavelength (248 nm). The first exposure uses a phase-shifting mask to pattern 0.1 micrometers isolated spaces. The resist used for the second exposure absorbs the 248 nm radiation strongly enough to produce a profile suitable for lift-off patterning.

Laser imageable photomask constructions

Abstract: Novel photomask blanks and methods for producing photomasks using laser-imaging apparatus. The photomask blanks include at least one layer that absorbs laser energy and ablates in response thereto, and, where unremoved as a result of the imaging process, perform the masking function by blocking the passage of actinic radiation; and a a mechanically strong, durable and flexible substrate that is substantially transparent to actinic radiation.

Digital scan model for focused ion beam induced gas etching

Abstract: Focused ion beam (FIB), assisted, gas etching has several advantages over physical sputtering in many FIB applications. Advantages include etch rate enhancements of 1–2 orders of magnitude, dramatically reduced redeposition of etched material on sidewalls in high‐aspect ratio structures, and reduced implantation of the primary ion species in the sample. Applications which benefit from FIB gas etching include photomask and x‐ray mask defect repair, integrated circuit modification for failure analysis, and sample preparation for scanning electron microscope and transmission electron microscope analysis. In this article, a simple model is presented which takes into account the ion beam and scanning parameters, gas flux, and basic material constants. Approximate formulas are given in terms of these parameters and compared to experimental results.

Phase shift photomask, phase shift photomask blank, and process for fabricating them

Abstract: The invention relates to a phase shift photomask in which the peripheral region portion of a phase shift layer is removed by a relatively simple procedure and which has no or little defect and is inexpensive, a blank therefor, and a process for fabricating them. The process includes the steps of forming phase shift layer 23 all over the surface of one side of transparent substrate 21, and immersing only the peripheral region of substrate 21 in etching solution 25 to etch away the peripheral region of phase shift layer 23, whereby phase shift layer 27 is confined within an area smaller than that of substrate 21.

Phase-shifting mask topography effects on lithographic image quality

Abstract: The impact of phase-shifting mask topography on wafer exposure was studied via simulations and experimentation using phase-shifting masks fabricated by etching the quartz to define the shifted areas. The influence of the refractive index of the chromium layer was shown to be minimal and for all the simulations, the refractive index was assumed to be 2.5 - 2.0 j at 248 nm. As the chromium profiles marginally influence the linewidth of the resist patterns, the simulated intensity assumes vertical profiles. Moreover, it was shown experimentally and using simulations that the quartz profiles have a large impact on the wafer results. For vertical quartz profiles, the intensity of the light going through the etched portion of the mask is lower than that going through the unetched portion of the mask and varies with feature size. The consequences are that 0 degree(s) and 180 degree(s) phases cannot be interchanged blindly during the layout of a phase-shifting mask and that the pinhole phase-defect repair technique consisting in etching 360 degree(s) phase slots in the quartz will not yield the same intensity profile as a defect- free region. These problems can be addressed either by optimizing the quartz profiles or by biasing the size of the features depending on the type of pattern.

Case for photomask

Abstract: The present invention relates to a case for a photomask to prevent generation of dust which might attach to and stain a photomask or the photomask pellicle. In a case for a photomask comprising a case main unit with an upper opening for accommodating the photomask and a lid for the opening of the case main unit, cushion materials are provided on the inner bottom of the case main unit and on the inner ceiling of the lid. The photomask is elastically squeezed between the cushion materials when accommodated. Thus, shaking and rattling during transportation are prevented to minimize the generation of dust. As the cushion material, a rubber material having a smooth surface on one side and a coarse surface on the other side is used.

Fused silica masks for printing uniform and phase adjusted gratings for distributed feedback lasers

Abstract: A method for producing durable fused silica self‐interference grating photomasks is described. These masks allow repeated printing of both uniform and phase adjusted gratings. Periods as fine as 200 nm have been demonstrated. The fabrication of these masks via holographic and focused ion beam lithography and their use as a lithography tool are explained. Distributed feedback lasers, with gratings made by this technique, were produced. These lasers operated in a single longitudinal mode at a wavelength of either 1.55 or 1.3 μm.

Real and imaginary phase-shifting masks

Abstract: Use of the phase-shifting mask in lithography allows substantial improvement of the resolution of commercial steppers for periodic circuit patterns, and, in certain cases, features smaller than 200 nm can be fabricated using i-line steppers ((lambda) equals 365 nm). There has therefore been much interest in developing this technology in recent years. In this paper, we examine and compare several approaches to evaluating mask designs for terminated periodic features, narrow gate lines, and contact holes, and compare the simulations with the actual results obtained when one attempts to use these designs in practice. Although we have found atomic force microscopy (AFM) to be a key tool for metrology, we conclude that there is a vital need for mask simulation, fabrication, inspection, and repair techniques to be developed further before these `imaginary' masks can be useful in the real world.

Conformal photomask for three-dimensional printed circuit board technology

Abstract: In a method for fabricating a reusable conformal photomask for a doubly contoured hemispherical substrate such as a radome or a three-dimensional printed circuit board, a light blocking material is deposited on a shell or tool corresponding to the shape of the radome or printed circuit board. A pattern is then formed in the light blocking material, and portions of the light blocking material corresponding to the pattern are removed. The resulting pattern corresponds to the pattern to be formed on the three-dimensional printed circuit board or radome. A light transmissive layer is then deposited over the light blocking layer for support. The light blocking material and the light transmissive material comprise the reusable conformal photomask which is then removed from the shell. The reusable conformal photomask can be used to form an image of the desired pattern on the three-dimensional printed circuit board or radome.

Process for producing the passivation layer of an active matrix substrate by back exposure

Abstract: A photoresist 10 is exposed to light from behind a substrate by using as photomask a wiring electrodes 2 and 4 and a switching element 8 which are individually composed of an opaque member, whereby a passivation layer 9 for the switching element 8 is patterned. By virtue of this method, a photomask becomes unnecessary and jogs of the passivation layer 9 can be formed outside the transparent pixel electrode 7. Therefore, an unsatisfactory orientation of a liquid crystal can be made invisible without enlarging the black matrix of a counter substrate. Furthermore, since a passivation layer can be removed in portions not requiring the passivation layer, image-sticking can be reduced and the quality of displayed picture can be greatly improved. The present invention makes it possible to reduce the number of photomasks used for production of an actively addressing substrate and improve the picture quality of a liquid crystal display.

Photomask with pellicle and method of treating and storing the same

Abstract: A photomask with pellicle which is treated so that even if the obverse and reverse surfaces of the photomask are stained with a trace amount of contaminative particles during cleaning, water content and a low-volatile component are prevented from adhering to such contaminative particles during storage, thereby preventing the photomask from becoming stained with passage of time. Also disclosed is a method of treating and storing the photomask. The photomask is subjected to a hydrophobic treatment by providing the obverse and reverse surfaces thereof with a trimethylsilyl film formed by a reaction of OH groups in these surfaces with 1,1,1,3,3,3-hexamethyldisilazane. Even if contaminative particles are attached to the obverse and reverse surfaces of the photomask in a trace amount during cleaning, no water content or low-volatile component will adhere to such contaminative particles during storage and/or transport of the photomask with a pellicle attached thereto, so that the photomask is prevented from becoming stained with passage of time. Accordingly, the photomask with pellicle can be stably stored for a long period of time and also stably transported, and it can be used any number of times for a long period of time.

Exposure apparatus and an exposure method using the same

Abstract: An exposure apparatus includes a first reflective type photomask 18a, a first mask stage 180a for mounting the first reflected type photomask 18a, a second reflective type photomask 18b, and a second mask stage 180b for mounting the second reflective type photomask 18b. Light 11a from a light source 11 is directed to the first and second reflective type photomasks 18a and 18b. The first exposure light 110c and the second exposure light 110b reflected by the first and second reflective type photomasks 18a and 18b are merged by a half mirror 30 to form a third exposure light 110e to expose a resist film 21a on a semiconductor substrate 21.

Blank for halftone phase shift photomask, halftone phase shift photomask and production thereof

Abstract: PURPOSE:To obtain a halftone phase shift photomask and a blank therefor capable of changing transmissivity at a phase shift part, dealing with various patterns after forming the blank or the photomask and mass producing. CONSTITUTION:The exposure light transmissivity of the halftone phase shift photomask layer is optionally changed within the range of 1% to 50% by the film forming process or a process to expose the photomask to the high temp. of >=150 deg.C, a process to expose it to an oxidizing atmosphere, and a process to expose it to a reducing atmosphere or the like separated from a photomask producing process. As a result, the exposure light transmissivity is desirably controlled after producing the blanks or photomask and the halftone phase shift photomask optimum for the dimension, area, arrangement, and shape or the like of a transfer pattern is obtained.

Photomask and method for patterning resist and formation of micro-condenser lens

Abstract: PURPOSE:To enable the formation of the micro-condenser lenses of a CCD image sensor by decreasing the spacings between the respective lenses. CONSTITUTION:A resist film 22 is applied on a resin layer 6 for the lenses flattened on a CCD image sensor body 1. This resist film 22 is patterned by using the photomask 14 having light shielding patterns formed by changing the distribution density of dot patterns, by which resist patterns 23 having the lens shape are formed; thereafter, the micro-condenser lenses 24 are formed on the resin layer 6 for the lenses by etching back.

Focused ion beam XeF2 etching of materials for phase‐shift masks

Abstract: Phase‐shift masks (PSMs) for photolithography are emerging as a very important technology for integrated circuit manufacture at 0.35 μm design rules and below using conventional optical step and repeat cameras at 365 and 248 nm. One of the biggest issues which remains unresolved in the fabrication of PSMs is defect repair. The sensitivity to printing of defects is much worse for phase defects than defects on conventional photomasks. In addition, the repair of defects in transparent dielectric materials at high‐spatial resolution presents many challenges. Focused ion beams (FIBs) offer the necessary spatial resolution for PSM repair. This article discusses the addition of etchant gas to the FIB process for enhanced etch rates, decreased optical effects from implanted ions and possible etch selectivity for process control.

Diffusion type photomask and production of optical parts using the same

Abstract: PURPOSE:To produce optical parts having pattern shapes and differences in level uniform over the entire area at a good yield and at a low cost by providing the surface of a light transparent substrate opposite from its mask pattern forming surface with a light diffusing member for diffusing transmitted light CONSTITUTION:This diffusion type photomask 1 is constituted by forming grid- like mask patterns 4 consisting of light shielding parts and apertures (transparent parts) by electron beams, UV rays, etc, on a photoresist 3 formed on one surface of the light transparent substrate 2 consisting of transparent glass or transparent resin The surface of such photomask 1 on the side opposite to the mask pattern 4 forming surface is joined with the planar light diffusing member 5, such as ground glass, by adhering, etc, by which the photomask is constituted Transmitted light is sufficiently diffused at the time of production of the optical parts and a photosensitive resin film 7 is irradiated uniformly with light of random directivity, by which the illuminance distribution over the entire area of the exposed surface of the optical parts is effectively improved according to such diffusion type photomask 1

Photomask blank and phase shift photomask

Abstract: A phase shift photomask and a photomask blank used to produce the same. A dry etching stopper layer, which is disposed between a substrate and a light-shielding layer or between the substrate and a phase shifter layer, is made of either a film mainly composed of tin oxide nitride, which has high etching selectivity and high permeability, or an alumina film formed by sputtering, followed by heat treatment carried out in an oxidizing atmosphere, thereby enabling the required overetching to be satisfactorily performed during etching of the phase shifter layer, and thus making it possible to effect precise phase control. In addition, it is possible to eliminate the occurrence of an in-plane transmittance distribution.

Thin-sheet fixing device

Abstract: PURPOSE: To provide a fixing device which can fix a photomask without lowering its plane accuracy, which is provided with a high-accuracy definite-position property in a direction perpendicular to the plane direction of the photomask and whose treatment capability can be enhanced. CONSTITUTION: The thin-sheet fixing device is provided with a frame 11, with a criterion piece 14 which is installed at the frame 11 and which supports a photomask 12, with a plate spring 17 one end of which is attached to the frame 11, whose rigidity is high in the plane direction of the photomask 12 and whose rigidity is low in a direction perpendicular to the plane direction and with a suction pocket 16 which is attached to the other end of the plate spring 17 and which fixes the photomask 12. COPYRIGHT: (C)1995,JPO

Exposure apparatus employing a photomask

Abstract: A reflection photomask includes a substrate and first and second reflection circuit patterns on the substrate so that light reflected from the first reflection circuit pattern has a different phase from light reflected from the second reflection circuit pattern. Interference between the reflected light bundles produces dark, i.e., non-illuminated, regions. An exposure apparatus includes a light source, a Koehler illumination optical system for irradiating a reflection photomask including a circuit pattern with light emitted from the light source, and a projection optical system for converging the light reflected from the reflection photomask onto a substrate to project the circuit pattern onto the substrate.

Phase shift photomask

Abstract: A phase shift photomask for forming a fine-line pattern with high dimensional accuracy even at different focus positions. The phase shift photomask has a transparent substrate (1) of quartz, for example, and a light-shielding film (2) of chromium, for example, provided on the substrate (1). The light-shielding film (2) is partially removed to form a first opening pattern (4a) and a second opening pattern (4b) with a very small width which is annularly provided in a peripheral region adjacent to the first opening pattern (4a). The light-shielding film (2c) is left in each of the four corners of the second opening pattern (4b). In addition, a phase shifter layer 3 is provided over either of the first or second opening patterns (4a, 4b).

Exposure method and photomask used in the same

Abstract: PURPOSE: To expose a bright isolated pattern such as a contact hole with sufficient depth of focus. CONSTITUTION: The surface 21 of an opening in a photomask is made convex or concave within the height of the edge of the light shielding film 12 of the photomask and the photomask is illuminated with an illuminating optical system whose numerical aperture NA almost satisfies the relation of NA= W.n.(n-1)/(2|R|) [where (n) is the refractive index of the transparent substrate 11 of the photomask, W is the width of the opening on the substrate 11 and R is the radius of curvature of the convex or concave surface 21 of the opening]. COPYRIGHT: (C)1994,JPO&Japio

Phase shift photomask and blank for phase shift photomask

Abstract: PURPOSE:To provide a phase shift photomask to which physical washing to be normally used for washing photomasks is applicable as it is and which has perpendicular working surfaces with high accuracy and the blanks for the phase shift photomask. CONSTITUTION:This phase shift photomask has transparent regions 5 and regions of a translucent layer 4 consisting of a chromium compd. formed by a physical vapor growth method on a transparent substrate 1. The transmittance of the regions of the translucent layer 4 is 3 to 35% when the transmittance of the transparent regions 5 is defined as 100%. The regions of the translucent layer 4 are shifted by substantially 180 deg. in the phase of an exposing wavelength from the transparent regions 5. The chromium compd. consists of chromium and oxygen or the chromium, oxygen and nitrogen or the chromium, oxygen and carbon or the chromium, oxygen, nitrogen and carbon and consists of a single layer film or >=2 layers of the multilayered films.

Photomask and pattern transfer method for transferring a pattern onto a substrate having different levels

Abstract: A photomask for projecting a transfer pattern onto a wafer having a plurality of regions with different surface levels includes a transparent substrate; a shielding member on the transparent substrate having a plurality of patterns for projection onto respective regions of the wafer; and an optical-path-length varying layer on at least one of the patterns corresponding to a region of the wafer other than a reference region of the wafer for changing the optical path length of light transmitted through the pattern by a length corresponding to the difference in surface level between the corresponding region and the reference region of the wafer. A pattern transfer method using such a photomask includes directing light onto the photomask; effecting a change in the position of the apparent object-side image surface for at least one pattern including the optical-path-length varying layer; and simultaneously forming on surfaces of the wafer regions image formation planes respectively corresponding to at least two patterns by image projection using light transmitted through the patterns.

Production of color filter

Abstract: PURPOSE:To provide the process for production of color filters which has advantages, such as instantaneous transferability of dyes since flash exposing is adopted, feasibility of uniform exposing over the entire part of a photomask, freedom from the receipt of the influence of the strain of the photomask, feasibility of the inexpensive production of an exposing device, and higher simplicity of stages and the exposing device than by the conventional process. CONSTITUTION:A transparent substrate 1 provided with a dye absorption layer 2 and a carrier film 4 having a film 3 of sublimatable dyes of a prescribed color are brought into tight contact with each other in such a manner that the dye adsorption layer 2 and the film 3 side of the sublimatable dye face each other. The photomask 5 having prescribed patterns is disposed on the carrier film 4. The sublimatable dyes at the points irradiated with the light by flash exposing are then transferred onto the dye adsorption layer 2 and thereafter the similar stages are repeated with the sublimatable dyes of the necessary colors, by which the color filters are produced.

Photomask having variable transmissivity and production of optical parts using the same

Abstract: PURPOSE:To provide a photomask capable of low-cost production of various diffraction gratings different from each other in cross-sectional shape and to produce optical parts with the photomask. CONSTITUTION:Groups each consisting of openings 1 and light shielding parts 2 alternately arranged at narrow intervals incapable of resolution at the time of exposure are arranged at intervals capable of resolution to obtain the objective photomask 3. The light transmissivity of the openings 1 is varied by varying the area ratio of the openings 1 to the light shielding parts 2. When this photomask 3 is used, optical parts such as a diffraction grating whose cross-sectional shape corresponds to a variation of the light transmissivity can be produced.

Holographic mask aligner

Abstract: Total internal reflection holography permits high-resolution, noncontact lithography over very large fields. A production lithographic system has been constructed employing specially developed illumination, focus, and alignment subsystems integrated onto a 6-in. substrate-handling mechanism. The system achieves an imaging resolution of 0.25 μm with a present overlay capability of ± 0.5 μm. A fine alignment system under development has demonstrated a 50-nm measurement accuracy. The technology is well suited to many applications, including the manufacture of flat panel displays, surlace acoustic wave devices, integrated optics, and optical storage disks.

Method for removing foreign matter of photomask

Abstract: PURPOSE:To completely remove foreign matter from a photomask without damaging the photomask by forming a polymer film on the photomask stuck with the foreign matter and removing this polymer film, thereby simultaneously removing the foreign matter as well. CONSTITUTION:The surface of the photomask (photomask substrate 1 and photomask patterns 2) stuck with the foreign matter 3 is spin coated with polyvinyl alcohol(PVA) and the coating is baked, by which a PVA film 4 is formed. The intermolecular force of the foreign matter 3 acts on the PVA film 4 as well and the intermolecular force between the photomask and the foreign matter 3 is conceivably relatively decreased when the film of the polymer, such as PVA, is formed to enclose the foreign matter 3. Then, the intermolecular force between the foreign matter 3 and the photomask is small and the PVA film 4 is the water-soluble polymer and, therefore, if the PVA film 4 is removed by washing with hot water, etc., the PVA film can be easily dissolved by the hot water and the foreign matter 3 is thereby removed together with the PVA film 4.

Chrome dry-etching for photomask fabrication

Abstract: The resolution and critical dimension control requirements for photomask fabrication are increasing at a dramatic rate due to advances in wafer lithography systems and photoresist technology. For example, phase shifting techniques for 5x reduction steppers require subresolution phase shifter elements as small as 0.5 micrometers to be patterned on the reticle. Unity magnification systems such as 1x optical steppers and deep UV 1x steppers require sub- half micron resolution on the reticle. The latest generation of electron-beam mask making systems is capable of patterning these structures in the resist film. However, traditional wet etch is not capable of successfully transferring the pattern from the resist into the chrome. This paper discusses a dry etch chrome process that has been developed at TRW. Sub-half micron resolution is characterized and explained in terms of chrome etching parameters. Selectivity and process sensitivities are explored for a potential manufacturing process. Finally, a dry etch process is used to fabricate actual reticles for an Ultratech 1500 1x optical stepper for use in a wafer manufacturing line.

Cleaning tool for development and etching device for photomask

Abstract: PURPOSE:To make a liquid for cleaning such as pure water splash into whole of a chamber of a development and etching device for photomask used for a production of a semiconductor device. CONSTITUTION:A tool 1 for cleaning having a three dimensional curved surface is set on a photomask holder 2 and is rotated by a motor 3. Simultaneously the liquid for cleaning such as pure water is sprayed from a spray nozzle of the development and etching device. Pure water or a chemical solution for cleaning is splashed into all the corner of the chamber and a developer or an etchant sticking to the chamber is washed out to keep the chamber clean. And as the chamber is kept in clean state, defect such as a pattern defect is almost disappeared and working efficiency is increased as cleaning of the device by a worker becomes unnecessary.