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The latest generations of CMOS are increasingly being patterned closer to the resolution limits of optical lithography, which is one of the reasons that their process windows are decreasing. Hence, control of the process gets more and more important and in-die critical-dimension (CD) measurements are gradually being introduced for the monitoring of the in-line lithographic process performance. Because an increasingly large portion of the CD-error-budget is already being consumed by the mask-making, there is also a strong tendency toward improving process control of the mask, which in turn leads to a rapid increase in the number of mask-CD measurements even within the die.The main two reasons for the larger contribution of the mask to the error budget at wafer level are 1) the statistical process variations of the mask-making process, and 2) the mask-error enhancement factor (MEEF), the magnification factor of reticle-to-wafer error. The latter, and its lithographic process dependence, are very much depending on the shape of a feature and its local vicinity in the design. For example a narrow dense binary line has a larger MEEF value than an isolated line and its partial derivative to defocus is much larger.In this work we use a commercial IC design to demonstrate a workflow that enables mask qualification on the basis of flexible specifications that satisfy manufacturing needs. This flow selects smart qualification sites combining two software options integrated in CATS mask-data transcription. The first retrieves MEEF information from Siliconversus-layout (SiVL) scripting and has various capabilities such as gathering MEEF-defocus behavior. The second is selection of relevant functional sites by using logic operations in the so-called CATS Marking software. The acquired information can then be used to generate realistic mask specifications and forms a cost-method to control both mask quality and price.

Besides the metrology performance of a CD measurement tool, its close integration into a manufacturing environment becomes more and more important. This is extremely driven by the ever increasing complexity of masks and their tightening specifications. Hence, this calls for the capability of fully automated CD measurements on a large number of dense and isolated lines and 2-dimensional features under production conditions.In this paper we report on such a highly automated measurement system for CD measurements from MueTec. Either an ASCII software interface or a specially developed software interface to connect the MueTec with the CATSTM mask data fracturing software handles the large amount of co-ordinates and other information like design images from the measurement sites and their surrounding, which are necessary for fully automated CD measurements. Because the latter is the standard in mask-making and data-formats, this level of automation guarantees a good industrial integration of the MueTec system.Fully automated and reliable CD measurements are based on very stable tool hardware and especially on a positioning stage with best possible positioning accuracy (range better 0.5 jim), significantly improved possibilities of software controlled positioning and an automated job set up and execution.The time gain in relation to existing measurement programs in the extent of supply has turned out to be dramatically large. The User Interfaces and their applications will be described.

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