As a result, intrinsic parameters fluctuations in deep nanometer dimensions caused by ler deserve adequately attentions. Fluctuations in uncertainty line edge roughness ler is the deviation of a feature edge as viewed topdown from a smooth, ideal shape that is, the edge deviations of a feature that occur on a dimensional scale smaller than the resolution limit of the imaging tool that was used to print the feature 1. Software for characterisation and quantification of nanoscale line. In previous study, the dependences of chemical gradient an indicator of ler on the halfpitch of line andspace patterns, the sensitivity, the sensitizer concentration, and the. Ler can be simply detected by afm or sem techniques, however, fast and nondestructive optical techniques should be developed in order to enable effective process. Novel approach to simulate finwidth line edge roughness. A line edge roughness analysis software is developed based on the canny edge detection algorithm with a double threshold, where threshold. Line edge roughness ler measurements using two types of atomic force microscopes and three types of tips are compared. Gate line edge roughness model for estimation of finfet. A straight line was drawn though the midaxis each of the black laths as shown. Lines perpendicular to this axial line were drawn to the peaks and valleys of the black laths. The root mean square rms value of the edge sigma value does not provide a complete characterization of ler since it cannot give information about its spatial complexity. Additionally, the true value is obscured by a number.
A line edge roughness analysis software is developed based on the canny edge detection algorithm with a double threshold, where threshold values are obtained by otsus method. The application platform method includes in a digital micromirror device dmd installed in an image projection. We illustrate this concept using afm scans of a photoresist pattern having pitch less than 300 nm and line width less than 150 nm. Then the characterization of the roughness of the obtained edges line edge roughness ler follows. As previously discussed, shot noise is an important contributor to line edge roughness. Quantification of lineedge roughness of photoresists. Numerous simulations and experiments on the impact of line edge roughness 24 have been reported. Pana adepartment of ece, university of texas, austin, tx usa bfreescale semiconductor, austin, tx usa abstract as the transistors are scaled down, undesirable performance mismatch in identically designed transistors in. Summit is an interactive offline analysis package for critical dimension cd and lineedgewidth roughness lerlwr processing of sem images. Ler is inversely proportional to the normalized image logslope nils.
The height difference between peaks and valleys is defined as the roughness. Issues in line edge and linewidth roughness metrology j. Summit home page euv technology summit software division. Impacts of work function variation and lineedge roughness. A search for the best and most complete description of lineedge roughness ler is presented. Measuring linewidth and line edge roughness versus exposure dose summary. A recent investigation of the effects of line edge roughness on device performance used 3d device modeling 5.
Modeling line edge roughness in templated, lamellar block. Edge position variation in euv patterns is significantly affected by stochastic phenomena that occur during the euv exposure and the chemical processes in photoresist. The true value of rms roughness depends upon the length of edge or line that is measured and the chosen sampling interval. The results indicate that wfv and fin ler have different impacts on i on and. Line edge roughness metrology using atomic force microscopes. The roughness of a line edge can be described as the deviation of the real line edge from a straight line. The parameters studied include the scanning electron microscopy. Electrical impact of lineedge roughness on sub45nm node standard cell yongchan ban a, savithri sundareswaranb, rajendran pandab,anddavidz. As critical dimensions shrink, line edge and width roughness ler and lwr become of. The application platform method includes in a digital micromirror device dmd installed in an. Spanos, fellow, ieee abstractwe present a model for estimating the impact of gate line edge roughness ler on the performance of doublegate dg finfet devices. Edge positions at 95% of the ridge height were determined on each scan line using asm. This is the largest valley depth deviation from the mean line within a sample length.
The line edge roughness of a chemically amplified resist ultimately depends on photoacid generation and the deprotection of the resists base monomers. Featureshape and lineedge roughness measurement of. An off line image analysis algorithm and software is developed for the calculation of line edge roughness ler of resist lines, and is successfully compared with the on line ler measurements. The measurement of lineedge roughness ler has recently become a topic of concern in the lithometrology community and the semiconductor industry as a whole. Design impacts of backendofline line edge roughness. The edge roughness of the polymer photoresist used to pattern those lines must. Modeling line edge roughness effects in sub 100 nanometer. Analysis of tradeoff relationships between resolution.
Backendof line line edge roughness eugene chu, yandong luo, and puneet gupta abstractone of the main issues of euv lithography is line edge roughness ler on photoresists, which signi. The embodiments described herein relate to a software application platform, which corrects nonuniform image patterns on a substrate. These tools have provided much needed information both on line and off line for quality control tests and the evaluation of a given fabrication process. This includes both vertical and spatial aspects of ler. Line edge roughness metrology software request pdf. Edge roughness measurements advanced surface microscopy. We report the results of an experimental and simulation study of the line edge roughness ler for resists patterned with next generation lithography tools such as extreme ultraviolet euv, electron beam, and xray. Electrical impact of lineedge roughness on sub45nm node.
In order to alleviate it, several options were explored in this work for the interferencelike lithography imaging conditions. Gate line edge roughness model for estimation of finfet performance variability kedar patel, senior member, ieee, tsujae king liu, fellow, ieee, and costas j. A great tool for roughness inspection in nanolithography. Us10289003b2 line edge roughness reduction via step size. The effect of several imageprocessing parameters affecting the fidelity of the off line ler measurement is examined. Measuring and minimizing line edge roughness in beol. Line edge roughness reduction for advanced metal gate. Additionally, the true value is obscured by a number of measurement errors. Study of line edge roughness and interactions of secondary.
Study of gate line edge roughness effects in 50 nm bulk. Linewidth and line edge roughness versus dose genisys gmbh. At 32 nm line width and below, ler can be a significant fraction of the feature dimensions. Reduction of line edge roughness ler in interference. In semiconductor electronics applications, line edge and linewidth roughness are generally measured using a root. A novel method for pushing the limits of line edge. For 193nm lithography, ler values of 4 nm and larger are common. The line edge roughness and other parameters of a line space pattern can be obtained all together by first selecting a region of interest roi then simply hitting the calculation button. Systematic assessment of the contributors of line edge. Line edge roughness ler is a serious problem that we encounter in nanolithography as pattern sizes shrink. A line edge with roughness can be simulated by doing an inverse fourier transform of this signal. The tradeoff relationships between resolution, line edge roughness ler, and sensitivity are a significant concern for the extendability of euv lithography. In this work, an analytical model of ler is presented and analyzed for yield loss induced by.
The ler behaviour can be shown as a function of the spatial frequency. Line edge and width roughness smoothing by plasma treatment article pdf available in journal of micro nanolithography, mems, and moems 2. Pdf line edge and width roughness smoothing by plasma. We present a model for estimating the impact of gate line edge roughness ler on the performance of doublegate dg finfet devices. The residuals of the fit form the roughness profile, which is shown in figure b. Fluctuations in the line edge of lithographic features, termed line edge roughness ler always exist. Summit sem metrology interactive toolbox summit software. Experimental and modelbased study of the robustness of line. Euv arrives, but more issues ahead improvement still needed for uptime, defectivity, line edge roughness and process flows.
Line and surface roughness measurements with the olympus lext ols4000 confocal microscope x. Issues in line edge and linewidth roughness metrology nist. In semiconductor electronics applications, line edge and linewidth roughness are generally measured using a root mean square rms metric. Sertac guneri, yazgi, tzvetan ivanov, mathias holz, ivo w. Thirteennanometergatelength dg finfets are investigated using a framework that links device performance to commonly used ler descriptors, namely, correlation length xi, rms amplitude or standard deviation sigma of the line edge. Block copolymers offer an appealing alternative to current lithographic techniques with regard to fabrication of nextgeneration microprocessors.
This featurerich analysis program integrates a variety of visualization tools and numerous builtin processing algorithms into a userfriendly gui. Line edge roughness is a common and potentially serious problem when patterning 193 nm photoresist both lithography and plasma etching play a role in ler polymer aggregates in the resist cause it to be susceptible to roughening during both developing and etching worse as resist is thinner and narrower, or when features are. A group from a leading greek research institute has developed software for offline acquisition and characterisation of sidewall lineedge roughness of printed nanofeatures based on the analysis of topdown images obtained by scanning electron microscope. The structure that was utilized assumed a single step in the gate length to emulate the effects of gate edge roughness. Reduction of line edge roughness ler in interferencelike large field lithography line edge roughness ler is seen as one of the most crucial challenges to be addressed in advanced technology nodes. However, if copolymers are to be useful on an industrial manufacturing scale, they must meet or exceed lithography specifications for placement and line edge roughness ler of resist features.
Suchit %t study of line edge roughness and interactions of secondary electrons in photoresists for euv lithography %i eecs. Depending on the distance between the scans, either high or low. Villarrubia national institute of standards and technology, gaithersburg, md, 20899, usa abstract. The impacts of work function variation wfv and fin line edge roughness fin ler on tfet and finfet device ion, ioff, cg, twoway nand delay, switching energy and leakage power are investigated and compared using 3d atomistic tcad mixedmode montecarlo simulations. The edge roughness of the polymer photoresist used to pattern those lines must be considered, since this could limit the precision of width and overlay placement control. Recipe batch mode to perform the same measurement on a set of images. However, as the title of one paper on the subject put it, do not always blame the photons. In particular for sidewall roughness of nanostructures a software has been developed for the analysis of topdown sem images of lithographic lines or lines resulting after etching of optoelectronic devices. Two critical issues concerning the ler of resist patterns are its characterization and its origin.
We graphed edge position as a function of distance along a given line and fit the resulting curve to a polynomial. The linewidth and line edge roughness ler of a negative ebeam resist are measured as a function of ebeam exposure dose. Line edge roughness spatial wavelength measurement repeated cd measurement with decreasing measurement boxes width and track the ler amplitude as the measurement box width decreases below the wavelength of a given roughness component, this component no longer contributes and the roughness amplitude decreases. T h e l i t h o g r a p h y e x p e r t february 2007 line edge roughness, part 1 while resolution is commonly discussed relative to optical limits, and sometimes even resist contrast limitations, it is quite possible that the ultimate limit of resolution will come from line edge roughness. Determination of optimal parameters for cdsem measurement of line edge roughness nist. We developed our own software to extract line edge waveforms by. Poor aerial image contrast aic has been applied intentionally to create rough line edges. We studied gate line edge roughness ler and its effect on electrical characteristics of. The performance of the software is demonstrated on features with a 200nm nominal pitch generated by currentcontrolled, fieldemission scanning probe lithography. A group from a leading greek research institute has developed software for off line acquisition and characterisation of sidewall line edge roughness of printed nanofeatures based on the analysis of topdown images obtained by scanning electron microscope.
Effects of different processing conditions on lineedge. Learn more about smooth rough edge, image processing. An image correction application relating to the ability to apply maskless lithography patterns to a substrate in a manufacturing process is disclosed. However, overdoing it will artificially lower your line edge roughness values. In order to get this missing information, we analyze the detected line edges as found from. Resist line edge roughness study for next generation. Line edge roughness ler lacerm works well with a wide range of images. Measuring linewidth and line edge roughness versus. Issues in line edge and linewidth roughness metrology. Summit is an interactive offline analysis package for critical dimension cd and lineedge width roughness lerlwr processing of sem images. Xx 6 r v maximum valley depth of roughness profile. Hence, it is important to understand and quantify the contribution of each of the stochastic effects to the edge roughness. Line edge roughness when variations in the width of a resist feature occur quickly over the length of the feature, this variation is called linewidth roughness.
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