A comparison has been made in terms of mask CD linearity measurements between the 2 tool versions of a 248nm based optical CD metrology tool for photomasks, i.e., the high-NA M5k-SWD and the through-pellicle M5k-LWD, as well as to a reticle SEM, i.e., the KLA-T 8250-XR. The measured pattern consists of lines and dots (dark features), and spaces arid contact holes (clear features), both in equal-lines-and-spaces and as isolated feature. Two masks have been measured with the same test pattern, i.e., a binary and a 9%-attPSM for 193nm lithography. The latter was especially challenging because typically such embedded phase shift masks are much more transparent at higher wavelengths than those for which they are optimized. All measurements on the M5k were made intentionally before calibration (apart fmm pitch calibration). The resolution performance of the M5k-LWD and the measurement offsets found between M5k and SEM, as well as between the two M5k-versions is discussed. In addition, two-dimensional metrology based on feature contour extraction from optical or from SEM images has been compared. Although its resolution is inherently lower than that of the high-NA M5k-SWD and a reticle SEM, the M5k-LWD offers a possibility to extend such assessment to pelliclized reticles, which is not possible on the alternative tools.
Gerd Scheuring, Alexander Petrashenko, Stefan Doebereiner, Frank Hillmann, Hans-Jurgen Bruck, Andrew Hourd, Anthony Grimshaw, Gordon Hughes, Shiuh-Bin Chen, Parkson Chen, Thomas Schatz, Thomas Struck, Paul van Adrichem, Herman Boerland, Sigrid Lehnigk
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 ?m), 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.
Andrew Hourd, Anthony Grimshaw, Gerd Scheuring, Christian Gittinger, Stefan Dobereiner, Frank Hillmann, Hans-Jurgen Bruck, Hans Hartmann, Volodymyr Ordynskyy, Kai Peter, Shiuh-Bin Chen, Parkson Chen, Rik Jonckheere, Vicky Philipsen, Thomas Schatz, Karl Sommer
The MueTec advanced CD metrology and review station, operating at the DUV (248nm) wavelength, has been extensively characterised for a number of feature types relevant to advanced (9Onm technology node) reticles. Performance for resolution capability and measurement repeatability is presented here for chrome-on-glass feature types concentrating upon lines and spaces, contact holes and dots. The system has already demonstrated the ability to image 100nm Cr lines and sub-nanometre (3- sigma) long-term repeatability on lines and spaces down to 200nm in size. We will now show that this performance level can be achieved and sustained at production levels of throughput and under typical cleanroom environmental conditions. Performance of new software tools to support the advanced metrology of 90-nm node reticles will also be introduced and their performance evaluated. Comparison will be made between CD-SEM measurements and the advanced optical metrology offered by the tool. Finally, reliability data for the tool —both in terms of mechanical and sustained repeatability performance — will be given, following prolonged trials in a production environment.
Andrew Hourd, Anthony Grimshaw, Gerd Scheuring, Christian Gittinger, Stefan Doebereiner, Frank Hillmann, Hans-Juergen Brueck, Shiuh-Bin Chen, Parkson Chen, Rik Jonckheere, Vicky Philipsen, Hans Hartmann, Volodymyr Ordynskyy, Kai Peter, Thomas Schaetz, Karl Sommer
The new MueTec , an advanced CD metrology and review station operating at DUV (248nm) wavelength, has been extensively characterised in a reticle production environment. Performance data including resolution, measurement repeatability and throughput will be discussed. The system has demonstrated the ability to image 100nm Cr lines and sub-nanometer (3-sigma) long-term repeatability on lines and spaces down to 200nm in size. Metrology capability on contact hole and serif structures will also be discussed.
The paper will also introduce the application of a long working distance DUV objective compatible with pelliclised masks. With a 9% EAPSM reticle for 193nm wavelength a very appropriate image contrast was obtained with both objective types, allowing reliable automated linearity measurements on this type of reticle also.
In addition to the metrology performance of the tool, its integration into a manufacturing environment will also be described. This will show how the availability of networked co-ordinate data (either in the form of ASCII files or CATS data) and the high-accuracy stage of the tool enable efficient, automated measurement of large numbers of dense features under production conditions.
Andrew Hourd, Anthony Grimshaw, Gerd Scheuring, Christian Gittinger, Hans-Juergen Brueck, Shiuh-Bin Chen, Parkson Chen, Hans Hartmann, Volodymyr Ordynskyy, Rik Jonckheere, Vicky Philipsen, Thomas Schaetz, Karl Sommer
Critical Dimension fidelity continues to be one of the key driving parameters defining photomask quality and printing performance. The present advanced optical CD metrology systems, operating at i-line, will very soon be challenged as viable tools owing to their restricted resolution and measurement linearity impact on the ability to produce repeatable measurements. Alternative measurement technologies such as CD-SEM and -AFM have started to appear, but are also not without tier concerns in the field of reticle CD metrology. This paper introduces a new optical metrology system (MueTec </M5k>/) operating at DUV wavelength (248nm), which has been specifically designed to meet the resolution and measurement repeatability requirements of reticle manufacture at the 130nm and 100nm nodes. The system is based upon a specially designed mechanical-optical platform for maximum stability and very advanced optical, illumination, alignment and software systems. The at wavelength operation of this system also makes it an ideal platform for defect printability analysis and review. The system is currently part of a European Commission funded assessment project (IST-2000-28086: McD'OR) to develop a testing strategy to verify the system performance, agree on equipment specifications and demonstrate its capability on advanced production reticles - including long-term reliability. It is the preliminary results from this evaluation that are presented here.
Qualification of a reticle is a very important step for a mask shop. For defect inspection, automatic die to die inspection can detect the random defects and the die to database inspection system can detect the missing patterns as well as the pattern placement of the reticle. When die size becomes larger, and the field size of the stepper lens is limited,it is a common practice that only one die is placed on a reticle.
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