In our work we discuss two approaches of offline CD-SEM recipe creation for both OPC qualification wafers and the introduction of new products to the manufacturing line using the Applied Materials OPC Check and Offline Recipe Editor (ORE) applications. We evaluate the stability of the offline created recipes against process variations for different OPC test layouts as well as for production measurements on multiple lots per week and compare the results to the performance of recipes created directly on the tool. Further, the success rate of recipe creation is evaluated. All offline recipes have been generated in advance of wafer availability using GDS data. The offline created recipes have shown pattern recognition success rates of up to 98% and measurement success rates of up to 99% for line/space as well as for contact-hole (CH) measurements without manual assists during measurement. These success rates are in the same order of magnitude as the rates typically reached by an experienced CD-SEM engineer creating the recipes directly on the tool.
In our work we investigate the influence of averaging varying numbers of measurement structures on process stability and CD uniformity. Measurements are performed on an Applied Materials VeritySEM CD-SEM system which provides the possibility to measure several lines or contact hole structures and to yield the average and 3 sigma value of all measured structures. We show that averaging significantly improves the single tool precision up to 30%. Additionally, a long term pilot test has shown that the range of the CD distribution of selected production layers is significantly decreased reducing the contribution of the measurement to the total CD budget resulting in a yield enhancement. Further, we discuss the influence of averaging on the contribution of short-range random CD variations for CD uniformity measurements. This is done by investigating the distribution of the CD difference between adjacent structures across the wafer. We show that increased averaging significantly reduces the contribution of random CD variations to the CD budget.
KEYWORDS: Electron microscopy, Atomic force microscopy, 3D metrology, Line edge roughness, Reconstruction algorithms, Scanners, Finite element methods, Photoresist processing, Critical dimension metrology, Process control
In this work, the profile reconstruction capability of the Applied Materials NanoSEM 3-D critical dimension-scanning electron microscopy is evaluated. The system allows the fully automatic reconstruction of profiles by evaluating profiles measured at two different beam tilt angles. From two different tilt angles up to 15 deg, the reconstruction of sidewall profiles is possible in a quick and nondestructive way, even for negatively sloped profiles. The sensitivity of profile reconstruction, especially with respect to height and undercut detection in dependence of structure height and beam tilt angle, is discussed. We investigate precision and accuracy of profile reconstruction by comparing results from profile reconstruction to AFM and cross-sectional (X-SEM) results. We show that the sidewall angle can accurately be detected for 193-nm resist structures even for negatively sloped profiles. This enables the system for production use especially for monitoring of such profiles. As the profile reconstruction is done with nearly the same speed as regular top-down measurements, a clear advantage over existing monitoring techniques is obvious.
We use the LER measurement capabilities of the Applied Materials NanoSEM 3D CD-SEM for the determination of LER for different manufacturing steps of the DRAM gate layer for the 90 nm technology node and below (after develop, after hard mask-open and final inspection steps). The system allows the fully automatic measurement of the LER as a 3 sigma value for top as well as bottom LER and yields also information about the spatial frequency along the line edge. We demonstrate precision of LER measurements (3 sigma) of less than 10% of the LER for resist structures as well as for etched structures with random or artificial LER within a range from 4 to 20 nm LER. The results agree with the requirements of the ITRS roadmap for structures down to 70 nm. We show on etched poly wafers containing artificial LER that the identification of discrete frequencies is possible down to LER values of below 5 nm (3 sigma). Based on these result we investigate LER on product wafers and show that the LER of left and right line edge, repsectively, are independent of each other. Additionally, no significant discrete frequencies are detected for all process steps under investigation, although the LER amplitude varies significantly in dependence of process conditions.
KEYWORDS: 3D metrology, Atomic force microscopy, Scanning electron microscopy, Silicon, Deep ultraviolet, Line edge roughness, Process control, Scanners, Finite element methods, 3D image processing
In this work the profile reconstruction capability of the Appplied Materials NanoSEM 3D CD-SEM is evaluated. The system allows the fully automatic reconstruction of profiles by evaluating profiles measured at two different beam tilt angles. From two different tilt angles up to 15 degrees the reconstruction of side-wall profiels is possible in a quick and non-destructive way even for negatively sloped profiles. The sensitivity of profile reconstruction especially with respect to height and undercut detection in dependence of structure height and beam tilt angle is discussed. We investigate precision and accuracy of profile reconstruction by comparing results from profile reconstruction to AFM and X-SEM results. We show that the side-wall angle can accurately be detected for 193nm resist structures even for negatively sloped profiles. This enables the system for the production use especially for monitoring of such profiles which cannot be detected by top-down CD-SEM so far.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.