Showing papers on "Mask inspection published in 1997"

X-ray lithography: Status, challenges, and outlook for 0.13 μm

Abstract: X-raylithography (XRL) has been under development since the early 1980s, and has reached a state of relative maturity. Numerous devices, including dense and complex integrated circuits, have been fabricated using XRL for one or more critical levels. While development of XRL technology itself continues, XRL is in use in several locations around the world for process development of advanced DRAM (1 Gb and beyond) and logic (0.18 μm and below) integrated circuits. Most of the tool set in use today comes from commercial vendors. Resolution using XRL has been demonstrated at dimensions down to 70 nm or below. Excellent critical dimension (CD) control results have been achieved in simple, single-layer, commercially available resists; for example, a total CD variation of 22 nm (3σ) has been achieved using a mask with a CD variation of 18 nm (3σ). Because of these capabilities, along with the experience and relative maturity of the technology, we believe that XRL is the technology best positioned to succeed optical lithography and be available for timely insertion into manufacturing for 0.13 μm ground rules, as well as to be extendible to 0.10 μm and below. In order to be accepted for manufacturing, however, significant work remains to be done. In particular, new e-beam mask writers and wafer aligners are needed, along with improved mask inspection and repair tools. Mask fabrication processes must also be advanced. The ability to satisfy these needs is not expected to be limited by fundamental physics, but rather is expected to depend on skilled engineering design and implementation.

Pattern transfer mask, mask inspection method and a mask inspection apparatus

Abstract: A mask inspection apparatus of the present invention includes an electron gun for irradiating an electron beam onto a mask with a pattern formed thereon, an electron lens for magnifying an electro-optic mask image passed through the mask, a fluorescent screen for converting the magnified electro-optic mask image to an optical mask image, an optical lens for optically magnifying the optical mask image, a detector for detecting the magnified optical mask image, and a comparator for inspection a defect in the pattern on the basis of the image. By doing so, it is possible to suppress aberrations resulting from the electro-optic magnification and, in addition, inspect the pattern with a high resolution through optical magnification. It is also possible to inspect the mask at its area and to inspect a defect at high speeds.

Image sensing method and defect detection algorithm for a 256-Mb and 1-Gb DRAM mask inspection system

Abstract: This paper describes an image sensing method and defect detection algorithm applied for a newly developed mask inspection system, the MC-2000, for 256 Mbit and 1 Gbit DRAM masks. The MC-2000, which utilizes i-line wavelength optics, is designed for less than 0.2 micrometer defect detection capability. An image sensing system employing a TDI (time delay integration) CCD image sensor is used for i-line image acquisition with an 80 Mpixel/sec data rate. Defect detection is done by comparing sensor image data with CAD data. Here we utilized our original differential comparison method which has very high sensitivity for defect detection.

New die-to-database mask inspection system with i-line optics for 256-Mb and 1-Gb DRAMs

Abstract: For mask defect inspection in 256 Mbit and 1 Gbit DRAMs, it is necessary to have high sensitivity of 0.2 - 0.1 micrometer. A new die-to-database mask inspection system MC-2000 for 256 Mbit and 1 Gbit DRAMs has been developed. This system has high resolution optics with i-line light and high NA lens, and high speed and high accuracy data processing circuit by new multilevel bit map pattern generator, so the system has both high detectability and high throughput. This paper describes system configuration which include optical system and mechanical system, the defect inspection method, and inspection performance including defect sensitivity.

Real-time line-width measurements: a new feature for reticle inspection systems

Abstract: The significance of line width control in mask production has become greater with the lessening of defect size. There are two conventional methods used for controlling line widths dimensions which employed in the manufacturing of masks for sub micron devices. These two methods are the critical dimensions (CD) measurement and the detection of edge defects. Achieving reliable and accurate control of line width errors is one of the most challenging tasks in mask production. Neither of the two methods cited above (namely CD measurement and the detection of edge defects) guarantees the detection of line width errors with good sensitivity over the whole mask area. This stems from the fact that CD measurement provides only statistical data on the mask features whereas applying edge defect detection method checks defects on each edge by itself, and does not supply information on the combined result of error detection on two adjacent edges. For example, a combination of a small edge defect together with a CD non- uniformity which are both within the allowed tolerance, may yield a significant line width error, which will not be detected using the conventional methods (see figure 1). A new approach for the detection of line width errors which overcomes this difficulty is presented. Based on this approach, a new sensitive line width error detector was developed and added to Orbot's RT-8000 die-to-database reticle inspection system. This innovative detector operates continuously during the mask inspection process and scans (inspects) the entire area of the reticle for line width errors. The detection is based on a comparison of measured line width that are taken on both the design database and the scanned image of the reticle. In section 2, the motivation for developing this new detector is presented. The section covers an analysis of various defect types, which are difficult to detect using conventional edge detection methods or, alternatively, CD measurements. In section 3, the basic concept of the new approach is introduced together with a description of the new detector and its characteristics. In section 4, the calibration process that took place in order to achieve reliable and repeatable line width measurements is presented. The description of an experiments conducted in order to evaluate the sensitivity of the new detector is given in section 5, followed by a report of the results of this evaluation. The conclusions are presented in section 6.

An enhanced system for automated wafer particle and crystalline defect inspection

Abstract: Detecting and quantifying contaminants and defects on micro-electronic grade silicon wafer surfaces is extremely important to ensure high yield of Ultra Large Scale Integration (ULSI) devices. Laser Surface Scanning Inspection Systems (SSIS) have been widely used to automate wafer particle inspection process. Although automated particle inspection sensitivities are capable of detection below 0.100 μm 1 , visual inspection continues to be used in silicon wafer manufacturing facilities. Visual inspection is required because conventional SSISs are not capable of identifying and classifying a variety of crystalline defects such as dislocations, slip lines, stacking faults, voids, and mounds. This paper discusses a new inspection method of wafer particle inspection using an improved SSIS equipped with both a dark channel and a Reconvergent Specular Detection (RSD) light channel. This new inspection process provides the capability of successfully identifying and quantifying crystalline material defects as well as distinguishing them from particles; therefore, it provides the solution for fully automated wafer inspection. This paper will also discuss and compare the results of the new automated wafer inspection process and visual inspection.

Integration of KLA Starlight for phase-shift mask manufacturing

Abstract: In the chrome-on-glass photomask inspection arena, KLA Starlight tool is mostly used in manufacturing mode as a particle detector and final plate quality verification, before mounting the pellicle, after pelliclization or both. When it applies to phase-shift reticles -- embedded attenuated as well as PhaseEdge --, there are other applications of Starlight defect detectivity, in addition to the above. This paper describes uses of Starlight technology at several process steps of PSM manufacturing. It addresses case of I-line and DUV Cr/MoSi embedded attenuated and multiple level quartz- etched alternating. Illustrations provided show several typical defect. Finally challenge to migrate from a development use into a full manufacturing integration is discussed. Based on Starlight performance, the price to pay to extend use of initially binary chrome-on-glass tool designed for production of phase-shift reticles is seized.

Next-generation mask strategy: are technologies ready for mass production of 256 MDRAM? Summary of Photomask Japan '97 panel discussion

Abstract: A panel discussion on mask technologies for 0.2-micrometer rule devices was held at Photomask Japan '97. This paper summarizes the discussion to make clear what is really needed to the mask, and what is a key issue to overcome. Required CD uniformity is satisfied by the improvement in resist/etching process and pattern writing accuracy. PSM key issues are defect inspection and repair. OPC is indispensable for 0.2 micrometer device, so the improvement in mask pattern fidelity and defect inspection technology is strongly required, but some limitation in OPC pattern design will be necessary to realize the OPC technology in mass production. To achieve both technology and cost, the partnership of captive and merchant mask shop, and the partnership of lithography, device, mask, equipment, and material vendors will be very important.

Mask inspection device

Abstract: PROBLEM TO BE SOLVED: To perform automatic inspection with high speed by providing a photodetecting means and a moving means which are provided with a light source and a photomask in between and detects the light that the opening part of the photomask transmits, and a judging means which compares the output of the photodetecting means with a reference value. SOLUTION: A light source 1 illuminates a photomask 5 uniformly. On an X-Y stage 3, a photodetector 2 disposed near the photomask 5 is mounted, and it scans the photomask 5. A signal processing circuit 4 amplifies the output signal of the photodetector 2, shapes the waveform of the signal, and compares it with a reference value set in advance. By this, whether good or bad of the photomask 5 is judged, and the judgment result is displayed on a monitor 11.

An Automatic Solder Joint Visual Inspection System For Small Volume Production

Abstract: In print circuit board assembly production cspecially small volume high mixed pi-ocess. solder joint visual inspection process is one of the most difficult process to be automated and it was very late to be done. We have built an automatic solder joint visual inspection system including an automatic inspection programming systcin linked with our CAD/CAM system through LAN(Loca1 Area Network). In this paper, system configuration of the automatic solder joint visual inspection system, results of inspection quality improvement experiment performed with a simulation system crcatcd by oursclvcs and also a way for increasing efficiency of using the inspection system will be ci I-ibccl. Results showed one of the most successful automatic solder joint visual inspection system for small volume high mixed surface mount printed circuit board