| AVS 58th Annual International Symposium and Exhibition | |
| Helium Ion Microscopy Focus Topic | Tuesday Sessions |
| Session HI+AS-TuA |
| Session: | Basics of Helium Ion Microscopy |
| Presenter: | Norbert Koster, TNO, Netherlands |
| Authors: | D.J. Maas, TNO, Netherlands E. van Veldhoven, TNO, Netherlands N.B. Koster, TNO, Netherlands P.F.A. Alkemade, Delft University of Technology, Netherlands E.W.J.M. van der Drift, Delft University of Technology, Netherlands |
| Correspondent: | Click to Email |
Although Helium Ion Microscopy (HIM) was introduced only a few years ago [1], many new application fields are emerging. Key issue is the directional interaction of the primary helium ion beam with the sample at and just below its surface with negligible backscattering. The sub-nanometer sized probe of the 10-35 keV ion beam generates Secondary Electrons (SEs) that have a typical energy between 0 and 20 eV. Taking all together the SE signal stems from an area that is very well localized around the point of incidence of the primary beam. This makes the HIM well-suited for both high-resolution imaging as well as high resolution nanofabrication [2]. We explore the possibilities to use the HIM simultaneously for imaging and nano patterning of EUVL masks.
The HIM is a high-resolution surface imaging tool. In practice, the optimum dose for imaging is a balance between maximizing S/N ratio, while minimizing sample damage. Imaging work at TNO van Leeuwenhoek Laboratory (VLL) [3] focuses at sensitive materials such as e.g. DUV and EUV resists and EUV masks, which are difficult to image in a SEM due to their charging behavior. An electron flood gun in the HIM offers effective charge cancellation, which enables high-resolution imaging of insulation structures and for pin pointing defects on a EUV reticle. In this presentation we will show images of particles down to 5 nm on reticles.
Furthermore, to explore the possibilities of the helium ion microscope as a nanofabrication tool, the HIM at the TNO VLL is equipped with a pattern generator and a gas injection system (GIS). This presentation will show our latest nano structuring results made with Helium Ion Beam Induced Processes: deposition and etching. It is expected that the unique capabilities of the HIM in combination with the GIS are suited for EUV mask repair. These capabilities offer the possibility of circuit repair in the latest and smallest semiconductor technology nodes (beyond 22 nm). In both cases sub-surface damage due to scattered He ions is a matter of concern and topic of investigation. At this moment we are capable of etching 13 nm lines with 25 nm spacing on a EUV dummy mask with approximately 80 nm of TaN absorber. Furthermore we demonstrate Pt deposited lines of 13 nm width at a 16 nm spacing.
References
[1] J. Morgan, J. Notte, R. Hill, and B. Ward, Microscopy Today 14, (2006) 24
[2] D.J. Maas et al., Proc. SPIE Vol. 7638, 763614 (2010) 1-8
[3] http://www.vanleeuwenhoeklab.com/