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Showing papers on "Mask inspection published in 1983"


Patent
12 May 1983
TL;DR: In this paper, a vector gradient within a matrix technique is used to develop candidate and cancellor information which is then logically manipulated to qualify the data obtained from each pixel matrix and then, after qualification, used to determine whether or not a defect has been detected.
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.

140 citations


Patent
Yasunobu Kawauchi1
15 Sep 1983
TL;DR: In this article, a mask inspection arrangement is described, including a magnetic disc memory for storing pattern data which has been used for operating a mask drawing apparatus, a data producing device for optically scanning a mask drawn by the mask drawing device and producing measured data indicative thereof, and a data converter for converting the pattern data from memory into a reference data in the form of dot pattern data for blanking an electron beam.
Abstract: A mask inspection arrangement is disclosed including a magnetic disc memory for storing pattern data which has been used for operating a mask drawing apparatus, a data producing device for optically scanning a mask drawn by the mask drawing apparatus and producing measured data indicative thereof, a data converter for converting the pattern data from memory into a reference data in the form of dot pattern data for blanking an electron beam in the mask drawing apparatus, and a comparator for comparing the measured data with the reference data and determining a correlation therebetween.

12 citations


Journal ArticleDOI
TL;DR: In this article, a Monte Carlo computer program was developed to simulate the backscattered electron signal from various types of two-dimensional gold-on-silicon structures, which was used to optimize the placement of the annular detector by examining the take-off angle distributions from different structures.
Abstract: The successful use of an electron‐beam lithography system for the inspection of x‐ray masks requires an in depth understanding of the scattering properties of the defects. A new Monte Carlo computer program has been developed to simulate the backscattered electron signal from various types of two‐dimensional gold‐on‐silicon structures. Simulation results for a variety of submicron patterns show excellent agreement with experimental backscattered electron signals from an annular silicon diode detector. It is found that the simulated energy signal, rather than the number signal, gives the best results. The program is used to optimize the placement of the annular detector by examining the take‐off angle distributions from different structures. The optimum take‐off angle range for this detector is found to be 30°–57.5° as opposed to the lower angle range favored for registration signals. It is also found through this investigation that small steps of gold on silicon will be the hardest defects to detect for t...

4 citations


Patent
21 Sep 1983
TL;DR: In this article, a mask inspection and correction apparatus is constituted of a controller 1 containing a memory device, mask inspection apparatus 2, exposing apparatus 3 which operates as a part of pattern correction apparatus, a controller 4 and an etching apparatus 5 which also operates as part of the pattern correcting apparatus.
Abstract: PURPOSE:To correct a defective part by storing defect of mask pattern detected to a memory medium, reproducing a corresponding defect of mask pattern by such data and selective irradiating the relevant area with light. CONSTITUTION:A mask inspection and correction apparatus is constituted of a controller 1 containing a memory device, a mask inspection apparatus 2, an exposing apparatus 3 which operates as a part of pattern correction apparatus, a controller 4 and an etching apparatus 5 which also operates as a part of the pattern correction apparatus. The apparatus 2 thus formed is further provided with an XY scanning stage 14 which places in parallel a pair of masks 13, an optical system consisting of an objective lens 17 and an eyepiece 18 and a linear encoder 21 which reads inspection position. Detected defect is then produced by the apparatus 3 and it is stored to a cassette tape 38 in the apparatus 4. The defect of mask 13 is corrected by the apparatus 5 based on such stored data.

4 citations


Proceedings ArticleDOI
07 Nov 1983
TL;DR: In this paper, the influence of mask defects on integrated circuits yield was studied by comparing the data given by an automatic mask inspection system to the die sort yield at probe test level, and it was found that the yield losses due to mask defects can vary from a few % to more than 50 %, as a function of the type of defects, layer involved and defect size.
Abstract: The influence of mask defects on integrated circuits yield was studied by comparing the data given by an automatic mask inspection system to the die sort yield at probe test level. It was found that the yield losses due to mask defects can vary from a few % to more than 50 %, as a function of the type of defects, layer involved and defect size.

2 citations


Proceedings ArticleDOI
Liang-Choo Hsia1, Lo-Soun Su1
07 Nov 1983
TL;DR: In this paper, Li et al. present a mask inspection methodology and procedure that involves direct X-Y measurements, where a group of dice is selected for overlay measurement; four measure-ment targets were laid out in the kerf of each die.
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.

2 citations


Proceedings ArticleDOI
Edward V. Weber1
07 Nov 1983
TL;DR: For over ten years IBM has been pursuing Manufacturing Electron Beam Systems in Manufacturing for direct wafer lithography exposure, which has resulted in three generations of systems for wafer exposure, each with a greater capability.
Abstract: For over ten years IBM has been pursuing Manufacturing Electron Beam Systems in Manufacturing for direct wafer lithography exposure. These efforts have resulted in three generations of systems for wafer exposure, each with a greater capability. These systems have been configured to minimize system ailments and to maximize throughput. Their principal application has been to reduce turn around time. They have provided satisfactory service in Manufacturing and in Development applications. Having proved themselves to be beneficial and reliable Manufacturing tools, electron beams are being implemented for additional applications. Mask exposure, mask inspection and module inspection are some of the newer applications for E-Beam systems, in IBM at East Fishkill.