193nm immersion lithography is the mainstream production technology for the 20nm and 14nm logic nodes. Considering multi-patterning as the technology to solve the very low k1 situation in the resolution equation puts extreme pressure on the intra-field overlay, to which mask registration error is a major error contributor. The International Technology Roadmap for Semiconductors (ITRS) requests a registration error below 4 nm for each mask of a multi-patterning set forming one layer on the wafer. For mask metrology at the 20nm and 14nm logic nodes, maintaining a precision-to-tolerance (P/T) ratio below 0.25 will be very challenging. Mask registration error impacts intra-field wafer overlay directly and has a major impact on wafer yield. We will discuss a solution to support full in-die registration metrology on reticles.
Technical demand for the photomask is becoming severer along with super-miniaturization of the semiconductor patterns as shown in the ITRS roadmap. Defect inspection is especially becoming more challenging and difficult as the photomask design rules continue to shrink toward hp65-45nm and below. One of the factors for such difficulties is aggressive OPC (Optical Proximity Correction), which makes defect inspection extremely difficult. In lithography, ArF immersion lithography will be predominantly used as one of the powerful candidates for the technology for hp65-45nm. Therefore, we have to assure zero printable defects assuming the use of ArF immersion lithography. Recently, there is another issue of increase in mask production cost, causing QCD balance to start to collapse. To cope with this new problem, tool operation is being considered for inspections ranging from accelerating inspection in R&D phase to reasonable inspection in production phase. In this paper, inspection concept for operation of inspection tools in R&D and production phases is discussed, with special focus on the aerial image based inspection.
A new configuration of spatial reticles is described for applications in real-time object tracking task. The motion of a planar object in a three-dimensional environment is decomposed into global motion parameters by measuring the temporal frequency of the reticles arranged on concentric circles in the image plane. Experiments were performed to maintain the size and the position of the object's image by controlling the attitude of a camera on the basis of the estimated motion parameters. The proposed system, composed of only a commercially available PC, exhibited good tracking performances with processing rate of 15 frames per second.
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