Use of layout automation and design-based metrology for defect test mask design and verification
This paper studies the impact of shape and local environment (pattern layout) on the ability to detect defects on the reticle and the extent to which they affect the dimension of the printed image on the wafer. The authors have made extensive use of design information to perform a thorough evaluation. OPC software was used to generate mask data that was comparable to product mask data. Defects were placed on the post-OPC layout and OPC software was also used to simulate the dimension of the defective features as printed on the wafer. "Design Based Metrology" was used to create accurate metrology recipes to support wafer and mask metrology. Ultimately the procedures described in this paper allow a direct correlation to be made between reticle inspectability and the impact of the same defects on wafer CD. Data is presented for the case of the Contact Hole layer of a "65nm" Logic technology, though the methods described in the paper are applicable to all layers.
Wafer fab mask qualification techniques and limitations
Mask inspection and qualification is a must for wafer fabs to ensure and guarantee high and stable yields. Single defect events can easily cause a million dollar loss through a defect duplicating onto the wafer. Several techniques and methods for mask qualification within a wafer fab are known but not all of them are neither used nor understood regarding their limitations. Increasing effort on existing tool platforms is necessary to detect the defects of interest which are at the limit of the tools specification - On the other hand next generation tools are very sensitive and therefore consume only a negligible amount of time for recipe optimization. Knowing the limits of each inspection tool helps to balance between effort and benefit. Masks with programmed defects of 90nm and 65nm design rule were used in order to compare the different available inspection techniques. During the course of this technical work, the authors concentrate mainly on two inspection techniques. The first one inspects the reticle itself using KLA-Tencor's SLF27 (TeraStar) and SL536 (TeraScan) tools. As the reticle gets inspected itself this is the so called "direct" mask defect inspection. The second inspection technique discussed is the "indirect" mask defect inspection which consists of printing the pattern on a blank wafer and use KLA-Tencor's bright-field wafer inspection tool (2xxx series) to inspect the wafer. Data of this work will include description of the techniques, inspection results, defect maps, sensitivity analysis, effort estimation as well as limitations for both techniques for the used design rule.
Wood Microbiology: Decay and Its Prevention
Introductory text on the principles of decay and discoloration processes in wood, with emphasis on the major fungal damages which may develop during the growth, storage, and use of wood. The characteristics, detection, effects, and control of microbial attacks are stressed. Provides a synthesis of the current literature on wood microbiology, a rapidly expanding field of study. (Abstractor's note: This is an important resource for conservation researchers studying the decay of wood in art and architecture.) The following is a list of chapter headings: 1) Introduction to wood microbiology; 2) Wood deterioration agents; 3) Characteristics and classification of fungi and bacteria; 4) Factors affecting the growth and survival of fungi in wood (fungal ecology); 5) Fungal metabolism in relation to wood decay; 6) The decay setting: some structural, chemical, and moisture features of wood in relation to decay development; 7) General features, recognition, and anatomical aspects of wood decay; 8) Chemical changes in wood caused by decay fungi; 9) Ultrastructural features of wood decay; 10) Changes caused by decay fungi in the strength and physical properties of wood; 11) Colonization and microbial interactions in wood decay; 12) Decays originating in the stems of living trees; 13) Biodeterioration of stored wood and its control; 14) Wood stains and discolorations; 15) Decay problems associated with some major uses of wood products; 16) Detection of internal decay; 17) Paint mildew and related degradative problems; 18) Natural decay resistance (wood durability); 19) Chemical protection of wood (wood preservation); and 20) Some trends in wood microbiology research and a new emphasis (biotechnology). -- AATA