Showing papers on "Photomask published in 1983"

Photomask inspection apparatus and method using corner comparator defect detection algorithm

Abstract: Defect detection apparatus including a mechanical and optical system for scanning duplicate areas of a photomask to be inspected, electronic means for converting the optically scanned information to digitized form, memory for storing such information, and means for comparing information obtained from one inspected area to the other inspected area to determine differences therebetween, such differences being classified as defects. The detection is accomplished using a vector gradient within a matrix technique to develop candidate and cancellor information which is then logically manipulated to qualify the data obtained from each pixel matrix and then, after qualification, is used to determine whether or not a defect has been detected. The subject invention has particular application to the detection of defects occurring at pattern corners within the inspected photomask and is specifically directed to overcoming difficulties previously encountered in detecting such defects.

Apparatus for inspecting a circuit pattern drawn on a photomask used in manufacturing large scale integrated circuits

Abstract: A photomask on which a circuit pattern is drawn is placed on an x-y table and is illuminated by a light source. A linear image sensor, on which the circuit pattern is imaged, measures the circuit pattern along the direction substantially perpendicular to a moving direction of the x-y table to generate an analog signal in units of measured positions on the mask. In order to eliminate the need for matching the size of the pixel to be measured with the pixel size of the design pattern data and allow effective detection of a defect smaller than the pixel size, an analog-to-digital converter is arranged to convert the analog signal to multi-level digital data, and a measured point calculation circuit calculates the position of the measured point in units smaller than the pixel size unit in accordance with the position of the x-y table. A reference data calculation circuit is provided to calculate multi-level reference digital data which is to be obtained when the design pattern is measured at a calculated measured point taking sensitivity distribution characteristics (including resolution characteristics of lens) of image sensor elements into consideration. A defect detector compares the measured data with the reference data to detect the presence or absence of defects of the circuit pattern on the photomask.

Photomask with corrected white defects

Abstract: A photomask with white defects that have corrected with a film comprising a mixture of silver and tantalum oxide. The film has a good resistance to chemicals.

Transfer apparatus provided with an auto-focusing mechanism

Abstract: A transfer apparatus comprises a projection device operable with a photomask having a semiconductor circuit pattern therein and includes a projection lens for projecting the image of the photomask to a photosensitive member sensitive to the image of the photomask projected by the projection lens. The apparatus further includes an illuminating device for illuminating the photomask, a memory circuit for storing the time characteristic Δl of a focus error occurring in the projection lens due to the exposure light from the photomask having passed through the projection lens, a history detector for detecting the illuminating history to/t of the illuminating device, a transmission signal forming device for forming a transmission signal regarding the transmission factor τ of the photomask used, a length measuring device for measuring the length of a part of the optical path between the photomask and the photosensitive member, an operation circuit for calculating a proper value in accordance with the output of the memory circuit, the output of the history detector and the transmission signal, and an adjusting device for adjusting the length of the optical path of the projection device until the proper value and the value measured by the length measuring device are in accord with each other.

Manufacture of semiconductor device

Abstract: PURPOSE:To form an integrated circuit by providing a prescribed circuit pattern on the same semiconductor substrate by a method wherein a light exposing method is employed using a photomask in the formation of one circuit pattern, a direct exposing method by an electron beam is used in formation of the other circuit, and both of these methods are combindly utilized. CONSTITUTION:The exposure of a first layer circuit net work pattern and the wafer of target marks 4a and 4b is performed by matching the marks 2a-2d of a wafer 1 to the marks 2a'-2d' on the photomark 3. As a result, the target marks 4a and 4b to be used for photomask positioning is patterned on the wafer 1 with the designed positioning relations against the registration marks 2a-2d, to be used for electron beam direct exposure, located on the wafer. Subsequently, when a direct exposure is performed using an electron beam in the pattern formation of the layer which is considered to be necessary, a positioning is performed by matching the registration marks 2a-2d, and this enables to form an accurate microscopic pattern. When a light exposure is performed, patterns can be formed by performing a mask-matching process using the target marks 4a and 4b.

Projection printing apparatus for printing a photomask

Abstract: A projection printing apparatus uses different lens systems during alignment and during printing. The lens system for alignment causes an alignment mark on mask to be imaged on the alignment mark on a wafer when the mask is illuminated by non-sensitizing light. The lens system for printing causes the circuit pattern of the mask to be illuminated by sensitizing light to be imaged on the wafer. The whole or part of the lens system for alignment is positioned outside of the circuit pattern image forming light path so as not to adversely affect the circuit pattern image on the wafer when the mask is illuminated by the sensitizing light.

Photomask and method of using same

Abstract: A photomask (60) used to form patterns on a resist coated semiconductor wafer is comprised of a light transmissive baseplate (62) having a thin metallic pattern (63) thereon; a plasma deposited coating (66) covering the patterned baseplate (62); a light transmissive, planar coverplate (68) in intimate contact with the coating (66) with an index matching fluid (72) interposed therebetween.

Method of fabricating integrated semiconductor circuit

Abstract: A method of fabricating an integrated semiconductor circuit device having a plurality of layers of circuit patterns, comprising forming the circuit pattern of at least one of the above mentioned layers by a direct exposure method using an electron beam, and forming the circuit pattern of at least one of the remaining layers by a light exposure method using a photomask.

Application Of Optical Microscopy To Dimensional Measurements In Microelectronics

Abstract: The problems of making accurate measurements of critical dimensions of features on integrated photomasks and silicon wafers are discussed and the currently employed optical measurement techniques described. Sources of systematic uncertainty in such measurements are considered. Measurement equipment developed at NPL and the NPL Photomask Linewidth Standard are described, and approaches to profile measurement of features on silicon wafers are discussed.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Method for marking base used for photomask blank

Abstract: PURPOSE:To form a mark easily recognizable and lasting semipermanently, by polishing the peripheral side of a base used for photomask blanks, and forming a prescribed mark on the polished face by precision working. CONSTITUTION:A protective film 6 is partly formed on the peripheral side of a base used for photomask blanks, and the side is polished by the relative movement of a polisher, such as polyurethane and an abrasive material, such as cerium oxide and water, a protective film 6 is formed on the polished part, and it is matted by a weak force with a sand belt 9. A prescribed mark for discriminating the kind of photomask blanks is formed on the polished part by precision working, using laser beams, ultrasonic waves, electron beams, etc.. In addition, the use of a polishing belt 10 having fixed abrasive grains can dispense with the matting step.

Inspecting method for photomask

Abstract: PURPOSE:To greatly simplify an inspecting stage for a working photomask by providing an optical system, a storage device, an arithmetic device, etc., for the inspection of the working photomask manufactured by using a common master photomask. CONSTITUTION:Firstly, the entire surface of a common master photomask 3 is inspected to find all faults, and whether each fault is harmful or not is judged to correct a harmful fault. The position of the area where a fault judged to be harmful substantially is present is stored in a storage device 4. Then, the entire surface of an optional working photomask is inspected to find all fault without discriminating between harmful and harmless faults, and positions of their areas are stored in the device 4. Then, the information obtained by subtracting information on a harmless fault that the master photomask 3 has from information on a fault of the workig photomask is regarded as information on the area of a harmful fault that the working mask manufactured before the working photomask detected in a manufacture lot has. This area is accessed and set in the visual field of an optical system 1 to perform correction.

Photomask and developing method using said mask

Abstract: PURPOSE:To obtain a developing method which is free from defects in the shapes of patterns owing to the stripped pieces of resist films in a photoetohing method by dissolving the photoresist films of the desired parts in the peripheral and side surfaces of a material to be worked by developing. CONSTITUTION:In a photomask and a developing method using said mask used for a photoetching method, this invention relates to a photomask (7) having the parts (9, 10) disposed with patterns, and the parts (13) corresponding to the peripheral and side surface parts of a wafer (14) which is the material to be worked where no patterns are disposed and a developing method for matching the photomask and the material to be worked, exposing and developing the photoresist films and removing the photoresist films in the peripheral and side surface parts of the material to be worked in the stage of developing; therefore the scattering of the resist films by the contact with jigs, etc. after the developing is obviated, and the defects in the shapes of patterns owing to the sticking of such small pieces are prevented.

Photomask and pattern evaluating method

Abstract: PURPOSE:To evaluate the size precision of a transfer pattern easily with high precision by detecting the zero-interval pattern of a size precision indication pattern transferred from a size precision reference pattern, and reading the distance between size precision reference pattern. CONSTITUTION:The zero-interval pattern of a size precision indication resist pattern transferred by size precision reference patterns 30, 31-34, and 3'1-3'4 is detected to read the distance between size precision indication resist patterns where intervals or overlaps of photomasks corresponding to the detected pattern are set. This extremely-easy operation realizes the easy and precise evaluation of the size precision of the transfer pattern of the mask pattern of a photomask.

Masked Ion Beam Lithography For Submicrometer Device Fabrication

Abstract: Masked ion beam lithography (MIBL) is a high resolution pattern replication technology that uses a collimated proton beam directed through a patterned mask to expose a resist-coated wafer in proximity to the mask A major step in the demonstration of MIBL as a practical lithography for submicrometer device processing has been achieved with the fabrication of functional n-channel metal oxide semiconductor (NMOS) devices We present details of the mask fabrication, resist and process technology development, and the resulting NMOS test chip characteristics

Manufacture of photomask for image pickup tube

Abstract: PURPOSE:To invisualize seam of deflection electrode after exposure by cutting both ends of transparent photomask like a saw tooth in accordance with the specification of deflection electrode pattern and the forming the cylindrical photomask through heat treatment after the saw tooth areas of both ends are alternately engaged. CONSTITUTION:After a vacuum-deposited metal film 2 and a photoresist 3 are formed at the internal wall of tube 1, a cylindrical photomask 4 forming the deflection electrode pattern is inserted, a fluorescent lamp 5 and a air bag 7 are provided at the inside, the air is supplied to the air bag 7 and thereby the bag expands and is closely in contact with the internal wall of photomask 4, and the deflection electrode is formed by exposure. In this case, both ends of photomask 4 are cut like a saw tooth in accordance with the deflection electrode pattern, the cylindrical photomask is formed by combining the saw tooth edges 8 alternately along the shape of cylindrical jig 17 and by heating such photomask with a jig 18. Such cylindrical photomask is molded and hardened. Thereby, the seam of deflection electrode can be invisualized after the exposure.

Photomask for projection exposure

Abstract: PURPOSE:To make the automatic positioning of a wafer and a photomask possible in projection exposure using a reflection optical system with respect to the photomask for exposure and transfer to be used during a photoetching stage in the production stage of semiconductor devices. CONSTITUTION:Target groups 1, 1' for automatic positioning of a photomask 2 for exposure and transfer and a semiconductor substrate 3 are disposed laterally symmetrically, and respectively and, a pair of target groups 1, 1', 2, 2' to be used for one time of exposure and transfer are disposed laterally symmetrically. Since the right and left targets of the wafer 3 and the mask 2 can be easily exposed in a slit region 4 only by the operation in X-, Y direction, the automatic positioning is facilitated and the reproducibility of the automatic positioning is markely improved. Thus productivity and the accuracy of positioning are improved.

Status Of X-Ray Lithography At H-P

Abstract: The various aspects of X-ray lithography at H-P in terms of mask-fabrication, resist development, alignment systems and source development are reviewed in their present status. Masks are being developed, flat within one micron, and with very low substrate defect density. PCMS is described as an X-ray resist with moderate sensitivity, but very good physical properties. Advanced source cooling techniques are expected to allow power densities up to 60KW/cm2, enhancing the source brightness. A very compact automatic exposure system is described, with alignment accuracy of .15 micron RMS.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Method and apparatus for inspecting photomask

Abstract: PURPOSE:To ensure the aptitude quality of a photomask as well as improve its production yield, by inspecting mask patterns after washing the mask surface while applying thereto a mechanical load of a desired intensity. CONSTITUTION:After a photomask 1 is brought above a washing means by a transfer mechanism, a mask-securing plate 10 is lifted up, and the mask 1 is transferred onto the securing plate 10. Then, the securing plate 10 is lowered to immerse the mask 1 in pure water 8 in the washing means. While ultrasonic vibrations are applied to the mask surface through a ultrasonic vibrator 16, the whole mask surface is scanned about two-three times by a rotary brush 15. Thereafter, the securing plate 10 is lifted up to the upper part of a washing vessel 8, and the mask 1 is transferred by the transfer mechanism located under the securing plate 10 to a stage 24 in a pattern inspecting means through a drying means to inspect the mask patterns, two by two, successively through optical microscopes 28a, 28b. Thus, all the photomasks having defective patterns not satisfying quality requirements can be judged to be failure.

Manufacture of metallic polishing body

Abstract: PURPOSE:To manufacture metallic polishing bodies each having a superior finishing polishing effect in large quantities by a photoetching method at a low cost, by relatively moving each metallic blank and an etching soln. to form the etched parts in a curved sectional shape and by using the remaining protrusions as teeth. CONSTITUTION:A photoresist film 2 is coated on a metallic blank 1 and prebaked. A tooth pattern is drawn and scaled down, and a precise photo plate having the pattern to be formed is mounted on the film 2 as a photomask 3 and exposed. After carrying out development, the photoresist film remaining on the blank 1 is baked. Thus, holes 4 having the same shape as the pattern of the photomask 3 are pierced, and metallic parts 5 are disclosed. While rotating the blank 1, an etching soln. is sprayed to form curved recesses 6 by etching and to remove the remaining film 2. Only the surface layer part having the formed teeth is finally quench-hardened.

X-ray collimator and exposing apparatus

Abstract: PURPOSE: To improve parallelism and permeability of soft X-ray flux and improve the performance of an exposing apparatus by a method wherein, when a semiconductor wafer, coated with a photoresist film, is irradiated by soft X-rays through a photomask, a soft X-ray collimating part made of glass is provided to an emission window of the soft X-rays. CONSTITUTION: A photomask chuck 17 which contains a wafer 18, coated with a photoresist film, and a chuck 19 holding the wafer is provided on a guide 20 moving at a constant speed and a photomask 16 with an IC pattern is put on the photomask chuck 17. A window 15 of a vacuum air-tight chamber 12 in which an electron gun 13 and a soft X-ray producing target 14 are contained is so provided as to face the mask 16. In this structure, a soft X-ray collimating part 7 made of glass is provided between the window 15 and the mask 16. The collimating part 7 is composed of countless fine piercing holes which have inside diameter (d) of an order of 10μm and a length (l) of an order of mm and these holes are fixed vertically in a bundle by a glass holding frame 8. COPYRIGHT: (C)1985,JPO&Japio

Emulsion photomask drying method

Abstract: PURPOSE:To prevent deformation of an emulsion photomask due to water drops, by coating a surfactant on the surface of an emulsion photomask wetted with water, and drying the mask CONSTITUTION:An emulsion containing diffused silver halide coated on a glass plate is exposed to a light pattern, then developed, fixed, and dried to provide an emulsion photomask for use in individual semiconductors and a small scale integrated circuit Before drying the wetted mask, a surfactant is first coated on its surface by spraqing or dipping, and water drops are removed by low speed spin drying or the like The surfactant reduces the surface tension of the liquid, permitting the drops to be converted into a flat film, and deformation of the pattern due to the surface tension and accordingly, deformation of the emulsion photomask due to water drops to be prevented

Metallic mask substrate

Abstract: PURPOSE:To easily hold a metallic mask substrate for a photomask with fingers without staining a metallic thin film on the substrate by using a part of the substrate as a holding part for handling on which the film is not present. CONSTITUTION:A part of a plurality of a photomask substrate having a metallic thin film 2 used in a stage for manufacturing a semiconductor device are used as holding parts 3 for handling on which the film 2 is not present. Even if the metallic mask substrate is large in size, it can be held by picking up the holding part between fingers, and the sticking of a stain such as a fingerprint to the metallic thin film is prevented.

Photomask correcting method

Abstract: PURPOSE:To readily effect the correction of a white pinhole defect portion, which is conventionally considered to be difficult, by forming a metal film at a defective part, such as a pinhole, in the area of a photomask which should be opaque, by means of electroless plating. CONSTITUTION:A photomask having a pinhole 4, known as ''white pinhole'' produced in the area 3 of a transparent substrate 1 which should be opaque is dipped in a pretreatment solution 5 for electroless plating. As a result, a film 6 of the pretreatment solution is formed all over the surface of the substrate 1 including the area 3 and the part of the pinhole 4 as a defective part. Next, only the part of the pinhole 4 is irradiated with ultraviolet rays or the like in the direction of an arrow A. As a result, metallic copper 7 is formed at the part by a reducing reaction, Thereafter, the photomask is dipped in an electroless plating bath; thereby, the plating reaction takes place at only the irradiated pinhole part to form metal films 8 and complete the correction.

Manufacture of josephson integrated circuit

Abstract: PURPOSE:To prevent the separation and flaws of photoresist attendant with the contact exposure and to impove the yield rate, by forming a convex part, which is thicker than a multilayer structure part of the circuit, in advance at a photomask part which is deviated from the region that is required for forming the Josephson integrated circuit. CONSTITUTION:The photomask 31 having a specified exposure pattern is formed. Then, the positive type photoresist is applied to the side of the mask 31 facing the Josephson integrated circuit. The exposure is performed by using a convex part forming mask pattern and development is performed. Thereafter, a metal film (thickness is 1-3mum) such as an SiO2 film or Cr is evaporated on the entire surface including the positive type photoresist. Said resist and the metal film such as the SiO2 or Cr thereon are removed, and the convex part 32 is formed. When a photoresist layer 33 is applied, a resist part 34 on the constitutional part of the Josephson circuit is high and a resist part 35 on a silicon substrate 1 is low. When the mask 31 is contacted with the resist layer 33, the convex part 35 is intensely adhered to the low resist part 35, but the high resist part 34 is not contacted with the photomask 31 owing to the convex part 32. Therefore the separation and flaws of the photoresist do not occur.

Production of photomask

Abstract: PURPOSE:To obtain uniform dimensions of photomasks, by drawing a mask pattern and a monitor pattern on a negative resist film with an electronic beam, detecting the thickness of the monitor pattern after development and baking and then etching selectively a light cut-off film. CONSTITUTION:A chrome thin film 2 is coated on a glass substrate 1, and a negative resist film 3 is coated on the film 2. A mask pattern 4' and a process monitor pattern 6' are drawn by an electronic beam after carrying out the prebaking. Then the development postbaking is carried out to form a mask pattern 4 and a process monitor pattern 6 respectively. The light 8 is irradiated to the pattern 6 to detect the thickness of the pattern 6 by means of the interference light, etc. Then the difference is obtained between the actual size and the design dimensions of the pattern 6, and the light cut-off film 10 of a region 9 equivalent to the difference of dimensions is deleted. Then the film 2 is selectively etched, and the film 10 is deleted. Thus a master mask is obtained. In such a way, the variance of dimensions can be eliminated.

Pellicle cover for photomask

Abstract: In a projecting printing system for forming an image on a radiation sensitive wafer, which system includes a mask having a transparent substrate with a pattern of opaque and transparent areas formed on the surface thereof, an illumination system for directing radiation through the mask to the radiation sensitive wafer, an optical system for forming a focused image of a mask pattern on the wafer, the improvement comprising a pellicle cover assembly for maintaining the images of any contaminate particles on the surface of the mask out of focus, said pellicle cover being fabricated from polymethylmethacrylate.

Direct Mask Overlay Inspection

Abstract: Direct mask overlay inspectionLiang -Choo Hsia and Lo -Soun SuMask Engineering, General Technology DivisionIBM Corporation, East Fishkill, New York 12533AbstractIn this paper, we present a mask inspection methodology and procedure that involvesdirect X -Y measurements. A group of dice is selected for overlay measurement; four measure-ment targets were laid out in the kerf of each die. The measured coordinates are then fit-ted to either a "historical" grid, which reflects the individual tool bias, or to an idealgrid squares fashion. Measurements are done using a Nikon X -Y laser interferometric mea-surement system, which provides a reference grid. The stability of the measurement systemis essential. We then apply appropriate statistics to the residual after the fit to deter-mine the overlay performance.Statistical methods play an important role in the product disposition. The acceptancecriterion is, however, a compromise between the cost for mask making and the final deviceyield. In order to satisfy the demand on mask houses for quality of masks and high volume,mixing lithographic tools in mask making has become more popular, in particular, mixingoptical and E -beam tools. In this paper, we also discuss the inspection procedure formixing different lithographic tools.IntroductionThe trend towards denser circuits, smaller device geometries, and larger wafer size hasmade mask overlay inspection most critical in VLSI manufacture. Misregistration problemscan give rise to large yield losses. Therefore, a reliable mask overlay inspection pro-cedure is essential. The measurements must be accurate and repeatable. On the other hand,the advent of projection aligner has dramatically increased the working life of a mask andhas made the number of masks needed per level decrease continuously. The near future maysee a situation where one to two masks suffice for each masking level, even for high volumeVLSI device manufacture. Therefore, it will be more economical to inspect each mask verycarefully. In particular, for bipolar device fabrication, which requires more than 16lithographic steps, the quality of each photomask has great impact on yield losses.As improvements have been made over the years, E -beam lithographic tools have beengradually accepted by mask makers for 1X mask making. Compared with optical mask making,E -beam mask making has the advantages of design flexibility, quick turnaround time, betterresolution, and perhaps better placement accuracy. However, E -beam mask making is expen-sive and the equipment is difficult to maintain. A cost -effective approach lies in mixingE -beam with optical mask making. The overlay matchability between the two, therefore,must first be guaranteed. In this paper, we present an inspection methodology and proced-ure for solving this problem.

Manufacture of photomask material

Abstract: PURPOSE:To obtain a photomask material almost free from defects and having superior etching characteristics, high acid and heat resistances by continuously forming an electrically conductive transparent film, a light shielding film and a reflection preventing film on a transparent support in order by sputtering. CONSTITUTION:An electrically conductive transparent film is formed on a transparent support by sputtering Sn or the like as a target in an Ar-O2 mixed atmosphere under 3X10 Torr by a DC magnetron method. Evacuation is carried out once, and Cr or the like is sputtered in Ar under 3X10 Torr to form a light shielding film. A reflection preventing film of chromium oxide or the like is then formed by sputtering Cr or the like as a target in a gaseous mixture of Ar with O2 under 3X10 Torr. Thus, a photomask material almost free from defects such as pinholes and having favorable etching characteristics, superior acid and heat resistances is obtd. The unevenness of the edges of the resulting pattern is <=+ or -0.03mum, and the extent of side etching is reduced.

Comparison and inspection of photomask and apparatus thereof

Abstract: PURPOSE:To detect existence or not existence of defective photomask pattern by seizing each corresponding area between the reticule pattern and photomask pattern with an optical means within the sight of the same size and by comparing them by scanning of inspection light. CONSTITUTION:The laser comparison and inspection beam generated from a laser light source 8 is inputted to microscopes 30, 32 through a scanning mirror 34. It scanns the correcting point between the reticule pattern 10 and photomask pattern 12 on the stages 22, 24 and passes condensers 40, 42. Thereby, an electric signal is generated in accordance with the shape of pattern from a photo-electric elements 44, 46 and a result of comparison and collation is outputted from a signal processing circuit 52. Magnification of objective microscopes 30, 32 is determined, for example, as 1:10, in case contraction ratio of patterns 10, 12 is 10:1, in view of optically seizing the corresponding area between the reticle pattern 10 and photomask pattern 12 within the sight of the same size.