Showing papers on "Photomask published in 1979"

Pattern inspection system

Abstract: A pattern inspection system for inspecting a pattern formed on a base, such as a photomask, by means of laser beam scanning which includes a device for detecting the body and edges of the pattern, a memory device having a plurality of memory units for separately storing the detected body and plurality of edges of the pattern, a device for measuring the width of the body of the pattern between two parallel edges of the pattern, a device for detecting and correcting missing pattern edges, a device for inverting the pattern, a device for reducing the pattern, and a device for eliminating pinholes and stains within the pattern.

Portable Conformable Mask-A Hybrid Near-Ultraviolet And Deep-Ultraviolet Patterning Technique

Abstract: Deep-UV conformable printing offers the capability of delineating submicrometer features with high aspect ratios. The profile of the resist image can easily be manipulated from overcut to vertical and undercut. However, making intimate contact between the mask and the wafer potentially induces defects. On the other hand, near-UV optical projection printing can be defect-free but cannot achieve a high aspect ratio in the photoresist image. In this paper a double layer resist system is used to combine the advantages of the two printing methods while eliminating the shortcomings. A thin AZ layer is spun on a thick PMMA layer. The AZ1350J layer is conventionally deliniated with a near-UV mask aligner. Because AZ1350J is opaque to deep-UV radiation, it acts as a built in conformable mask which can be carried with the wafer to a deep-UV blanket-exposure station to delineate the PMMA layer.

Apparatus and method for fine alignment of a photomask to a semiconductor wafer

Abstract: A method and apparatus are disclosed for fine aligning a photomask to a semiconductor using the interference and diffraction effects produced by coherent light impinging upon or passing through repetitive patterns on a photomask and a semiconductor. A plurality of photodetectors are employed to convert the interference information into phase dependent electrical signals that are used to control conventional X, Y and θ workpiece positioning mechanisms.

Method for making thermochromic photomasks

Abstract: An orange colored photomask visually transmissive to yellow-orange light formed by heating an exposed and developed silver-halide emulsion coated photomask. At approximately 200° C., black silver in the photomask begins to show evidence of conversion to a transparent red material. At a temperature of 250° C. to 320° C., the black silver opaque images are rapidly converted to orange, visually transmissive images which are essentially opaque to the ultraviolet light used to expose photoresist covered silicon wafers, while clear areas remain clear.

Electron beam testing method and apparatus of mask

Abstract: A method and an apparatus for testing a mask by an electron beam are disclosed in which the electron beam probe is first incident upon a predetermined point on a mask pattern of a photomask used to fabricate a semiconductor integrated circuit, the mask pattern is scanned by the electron beam probe from the predetermined point in a direction, the scanning operation is stopped when the electron beam probe reaches an edge of the mask pattern, the position of the edge or the distance between the predetermined point and the edge is determined by the number of pulse required to deflect the electron beam probe by a desired amount, and the position or distance thus determined is compared with the design data of the mask pattern to examine the dimensions of the mask pattern.

Photomask correcting method

Abstract: PURPOSE:To correct the image defective part of a photomask and effectively utilize resources by forming a photoresist layer on the photomask, selectively exposing the layer and implanting high energy particles into the resulting photoresist image on the defective part while accelerating them. CONSTITUTION:A photoresist is applied to a photomask having inorg. light shielding film pattern 12 including an image defective part, and it is prebaked to form photoresist layer 13. Layer 13 is selectively exposed to form photoresist layer 14 covering the defective part alone, and then desired high energy particles are implanted into layer 14 with predetermined accelerating energy. Thus, layer 14 is hardened, modified, and converted into ion implanted photoresist layer 16. Since layer 16 has high adhesion to glass substrate 9 and inorg. light shielding film 12, superior mechanical strength and light shielding properties, the resulting photomask can be used under conditions similar to those of an ordinary hard mask.

A new fabrication method of small-dimension devices—Multiple-wall self-aligned devices

Abstract: The fabrication procedure and device characteristics of the multiple-wall self-aligned devices are described. Two neighboring resist walls are photolithographed on a silicon wafer to protect the intervening region between the walls from diagonal incident ion beams. By using this shadowing effect in ion-beam etching and the ion implantation, only one photomask or one electron-beam exposure is required to fabricate the major components of MOSFET's or bipolar transistors. The results of performance testing of MOS and bipolar transistors fabricated with this process are presented.

Photomask base plate

Abstract: PURPOSE:To prevent damage, etc. of a photomask base plate in handling and facilitate removal of dust and foreign matter adhered to the plate during storage by covering the surface of the transparent substrate of the plate partially having an opaque thin film pattern with a transparent protective substrate followed by hermetical seaing. CONSTITUTION:The photomask base plate is composed of substrate 1 which is transparent to light and thin film pattern 2 which is opaque to light and has been attached to part of the surface of substrate 1. In order to protect the surfaces of pattern 2 and substrate 1 by hermetical sealing, protective substrate 3 which is transparent to light and tough is bonded with adhesive 4 of high transparency, e.g. polyvinyl butyral resin or epoxy resin for optoelectronics. As the material of substrate 3 glass, quartz, plastics or the like is chosen like the material of substrate 1 in accordance with light used. Thus, powerful chemical and physical washing can be performed to easily remove dust and foreign matter.

Manufacture of photomask

Abstract: PURPOSE:To obtain a photomask of high accuracy for LSI, etc. by forming a film of a specified metal and a film of the metal oxide on a glass substrate; coating a polymer resist; forming a pattern by applying electron beams or the like; and carrying out specified etching. CONSTITUTION:Cr film 12 and chromium oxide film 13 are formed on glass substrate 11 by sputtering or other method, and photoresist or electron beam resist film 14 is coated. The films are then exposed to light or electron beams through a pattern for LSI or the like and developed to form opening portion 15, thus obtaining a resist pattern. After baking to improve the adhesive properties of films 13, 14, exposed film 13 is removed by etching with mixed gas plasma of halogen type gas such as Cl2 and CO, NO, H2 or the like. Film 13 is then removed by etching with O2 plasma or the like, and film 12 is removed by etching with mixed gas plasma contg. Cl2 and O2 to obtain desired mask E.

High‐speed, low‐overhead electron beam direct slice writing system

Abstract: Electron beam writing systems have been primarily used for photomask and reticle fabrication because of the limited throughput ahievable. A vector‐scan beam writing system (EBSP) has been developed with a 1–1.25 μm resolution capability and ±0.25 μm pattern overlay accuracy and a potential throughput capability of 14 3‐in. slices/h for 1–1.25 μm minimum pattern geometries and 20 3‐in. slices/h for 2.5 μm minimum pattern geometries. This paper discusses the throughput factors for vector‐scan e‐beam systems and describes the new developments and improvements to tne major subsystems of the earlier photomask machine (EBM II) which were necessary to achieve this order of magnitude improvement in throughput.

Pattern correcting device

Abstract: PURPOSE: To make visual recognition of correcting sections sure and easy even in the case of a photomask drawn densely with patterns by projecting optical marks showing correcting sections from above the working table placed thereon with the photomask. CONSTITUTION: A pattern correcting device is formed by a defect position projector 1 irradiating the light of a light source 1b past the hole V of a shading plate 1a to the desired section on a photomask by a lens 1c, a stage T disposed on a working table 3 via swivel balls Ba and a light source N for lighting installed under the stage T. While the photomask 2 on the stage T is being lighted over the entire part from the back by the light source N for lighting via a light diffusing plate D, a light spot is irradiated from the projector 1 to indicate the defect position on the mask 2, whereby the pattern correcting work is carried out. With said device, the stage T is freely movable on the working table 3; moreover the defect position may be indicated always correctly despite the movement of the stage T by fixing the projector 1 to the stage T by means of a supporting arm As, and therefore the working efficiency is good. COPYRIGHT: (C)1981,JPO&Japio

Optical Measuring Technology Of The Micropatterns

Abstract: This paper describes three optical measuring machines which have been recently developed for state-of-the-art microlithography, as follows: (1) X-Y measuring machine for checking photomask registration. Utilizing a photoelectric microscope and a laser interferometer, this machine has a repeatability of less than O.lμm, covering a measuring range of 6 inches. (2) Measuring machine for critical line width (1 - 100µm) of photomask. This machine likewise utilizes the latest photoelectric detection technology; it has a repeatability of approximately 0.05µm. (3) Measuring machine for wafer and photomask micropatterns. A newly developed system which makes use of laser beam technology is incorporated in this machine; measurement repeatability is approximately 0.05µm.

Method and device for selective treatment

Abstract: PURPOSE: To raise the accuracy of treatment, by measuring the area of the opening of a mask, through which laser light is transmitted, through a television camera and adjusting the area of the opening when inradiating the laser light upon an electric insulator to selectively treat it. CONSTITUTION: A photomask 1 to be treated is interposed between an objective lens 2 and a condensing lens 3 over an illumination lamp 4. A half mirror 5, an intermediate lens 6 and a television camera 7 are installed over the photomask 1. An iris mechanism made of four plates 9, which are driven by pulse motors 10, is provided near the mirror 5. Light from a laser oscillator 11 is transmitted through the opening 19 of the iris mechanism and reflected by the mirror and irradiated upon the mask 1. A measuring circuit 25 is connected to the television camera 7. A comparison and adjustment circuit 26 is operated by the output of the measuring circuit 25. The motors 10 are controlled by the output of the circuit 26 to regulate the area of the opening 19. The result of the regulation is monitored through a monitor television set 8. COPYRIGHT: (C)1980,JPO&Japio

Method of producing metal filter

Abstract: PURPOSE: To produce a metal filter for sieving ultrafine particles having uniform holes and high aperture rate by an electroforming method on an electroconductive base plate using a photomask having a light-shielding material of interference fringe pattern obtained by the interference of laser light. CONSTITUTION: In a transparent base plate 17 made of glass or the like there is provided a layer of a light-shielding material such as Cr or the like thereby to produce a mask original plate, and a phtotsensitive material layer 19 is applied on the layer 18. Then, an interference fringe pattern is baked on the layer 19, and developed to form a resist pattern 19A. Then, the exposed layer 18 is subjected to etching through the layer 19A. Thereafter, the resist 19A is exfoliated to obtain the object photomask P. Then, by use of the photomask P a fine diffraction grating pattern is baked on a photoresist layer 20 by ultraviolet rays 20, and developed to produce a resist pattern 22A. Then, a metal 23 is electroplated by using an ordinary electroforming method. Then, the metal 23 is exfoliated to obtain a metal filter having uniform ultrafine holes having a hole diameter of, for instance, 1μ or less, and a high aperture rate. COPYRIGHT: (C)1980,JPO&Japio

Computerized Optical Systems For Ilinewidth And Film-Thickness Measurements On Microelectronic Circuits

Abstract: Nanometrics has designed two computerized optical measurement systems for use in micro-electronics photomask and wafer process control. The NanoSpec/AFT Automatic Film. Thickness Measurement System car measure with good precision the thickness of silicon dioxide, silicon nitride, polysilicon, photoresist and other films from. several hundred angstroms to several microns. A nine micron diameter measuring spot is employed which allows gates and pads as small as 10 microns to be measured. Recently its use has been extended to thickness measurement of photo and electron beam resists on chromium photomasks as well as wafers. The Nano-line Critical Dimension Computer is a line-width measuring instrument comprised of a micro-densitometer adapted to a high-magnification microscope and interfaced to a digital micro-processor computer. It can measure lines from less than one micron to 100 microns on masks and wafers with good precision. Both systems employ similar computer methods, are non-destructive, and very reliable in the manufacturing environment. They also provide results which minimize operator error. Their computers incorporate large memory capacity to store statistical data which allows the manufacturing engineer to determine and correct process variations and drift on a prompt basis.© (1979) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Development of a Two-Step E-Beam Lithography Process For Submicron Surface Acoustic Wave (SAW) Device Fabrication

Abstract: A two-step fabrication process was developed which has produced previously unobtainable high frequency surface acoustic wave (SAW) devices. In addition, the design-to-test cycle time has been shortened significantly to allow an effective interactive design procedure. The SAW structure places some of the most stringent precision requirements on current electron-beam lithography, since finger placement errors are directly related to phase errors in the electrical performance of bandpass or pulse compression filters. A form of double precision is implemented in the interface software to enable successful patterning of the monotonic variation in line width from less than 0.4 pm to more than 0.9 pm required for a 1 to 2 GHz pulse compressor. Compensation for proximity effects due to the electron beam profile was also implemented. Alignment accuracy within a field is controlled to within ±250 A and field placement is accomplished via a laser interferometer controlled stage. Several alternative processes, including direct slice writing, reverse liftoff, and x-ray lithography are compared. Once the E-beam master is generated, large area contact replication is achieved using a modified conformable mask printer. This process has extended the range of SAW device performance beyond 2 GHz in a fundamental mode which, represents a significant advancement in microfabrication. Three-day turnaround from design to packaged devices was demonstrated using this technique.

Manufacture of photomask

Abstract: PURPOSE:To form a negative pattern which excels in the resolution by making use of the excellent resolution characteristics of the positive resist. CONSTITUTION:The photomask is produced in order to etch the patterned resist as well as the positive-negative inverted pattern in case the blank photomask is etched. For this purpose, conducting electrode 3 of Au, Ni or the like is provided on the blank photomask which contains the thin film composed of 2nd basement material 2 of Si, Bi, Cr or the like on 1st basement material 1 of the glass, quartz, sapphire or the like. On the blank mask substrate of such 3-layer structure, the patterned electronic resist or photo resist 4 is provided. The metals of Au, Ni and the like are provided selectively through the selective plating method to the area where the resist patterned from the photomask does not exist, and then the resist is exfoliated. Then the patterned metal film thus obtained is used for the mask to carry out the chemical or physical etching, thus etching both the resist pattern obtained first and the positive-negative inverted pattern into the photomask.

Mask Fabrication With Vector Scan Electron Beam System

Abstract: An automated electron beam lithographic system, Vector-Scan-1, was designed to write patterns directly on device wafers as well as generate chrome masks for conventional optical processing. Due to its high current density, conventional AZ-1350 resist can be used directly in the mask making process. Its vector scan capability not only saves exposure time but also provides extremely compact pattern data. Using its laser interferometer servo control, extremely large capacity chips in both 1X masters and 10X reticles can be exposed with relative ease. The accuracy and speed of generating high resolution 1X chrome masks and 10X reticles generated by the VS-1 lithographic system for magnetic bubble fabrication are discussed in detail.

Photomask material for far ultraviolet exposure

Abstract: PURPOSE:To obtain a photomask material low in reflectance of far ultraviolet rays and high in resolution, for use in fabrication of high density integrated circuits or the like, by forming a metallic Cr layer and a Cr oxide layer each in a specified film thickness range on a transparent synthetic quartz substrate. CONSTITUTION:A metallic Cr layer is formed on a synthetic quartz substrate having 180-260nm spectral transmittance >=90% in 50-70nm film thickness, and a Cr oxide layer of 5-8nm film thickness is formed on the Cr layer so as to reduce its spectral reflectance of the far ultraviolet rays in the region of 180-260nm wavelength to a minimal value <=5%, thus permitting a material for fabricating a photomask capable of forming a minute pattern of about 1mum size by far ultraviolet exposure to be obtained. Reduction of reflectance permits the light reflected by the Cr oxide layer to be prevented from exposing the photoresist again, and from disabling transfer of minute patterns, and therefore, a high resolution photomask to be obtained.

Preparation of photomask

Abstract: PURPOSE:To prepare a hard type photomask by using a combination of means of electron beam irradiation, etching, etc against a polymer layer formed on a low reflection chromium layer provided on a glass substrate CONSTITUTION:Resist 14 for electron beams is coated on a low reflection chromium layer consisting of chromium film 12 and chromium oxide film 13 formed on glass substrate 11, resist 14 is irradiated by electron beams 10 patternwise as it is kept at a constant high temperature, and resist 14 in the irradiated parts is evaporated to form exposed parts 15 of the chromium layer The low reflection chromium layer under parts 15 is removed by wet chemical etching, dry etching, or such method using the above resist film as a mask, and remaining resist 14 is removed to obtain a photomask

Manufacture of durable photomask

Abstract: PURPOSE:To form an essentially flat mask image in a glass base and to improve durability, by dispersing Ag or Cu into the glass base using a silver halide emulsion layer

Optical measurement of the IC photomask pattern area.

Abstract: Optical measurement of the integrated-circuit (IC) photomask pattern area is performed. The relationship between aperture dimension and diverging angle of diffracted light is numerically estimated after scalar electromagnetic theory, and the expected measurement error is derived. The experimental measurement of the pattern area is made using typical IC photomasks. In the experiment, converging optics and an integrating sphere are suitably arranged so as to minimize the error introduced by omitting the higher-order diffraction. Some of the measured data are compared with values which are calculated from the IC layout design data, and they are found to be in good agreement.