High-Precision nm-Coatings for EUV and X-Ray Optical Applications

AIP Conference Proceedings, 2007

The topic of this paper is the fabrication and characterization of EUV reflective coatings based on molybdenum/silicon (Mo/Si) multilayers. For the fabrication of such nanometer structures, the technologies of magnetron sputter deposition (MSD) and ion beam sputter deposition (IBSD) are used in IWS Dresden. The main challenges for extreme ultraviolet (EUV) optics are high reflectance, precise thickness profiles, low internal stress and long-term stability. Reflectances > 70 %, uniformities > 99.9 % and overall internal stresses < 20 MPa have been reached. In addition to sophisticated deposition technologies, precise metrology tools are mandatory for the characterization of the coatings. Together with a number of partners, IWS Dresden has developed a stand-alone EUV reflectometer that makes it possible to measure EUV reflectance R and peak position O on substrates with diameters of up to 500 mm. Current improvements of the reflectometer resulted in differences compared to calibrated measurements at PTB/BESSY of 'R = -0.2…-0.6 % and 'O 50 = +4…+9 pm.

Microelectronic Engineering, 2001

In the past, the successful application of PLD for X-ray multilayer synthesis has already been demonstrated for C-spacer systems. Recently, the method has also been tested for Mo / Si layer stacks. A UHV-coating machine has been used to prepare X-ray mirrors on 4 in. substrates. The ablation of both Mo and Si targets was carried out by Nd:YAG laser irradiation using the third harmonic (l 5 355 nm) with a pulse energy E 5 275 mJ and a pulse width t 5 4. .. 6 ns. p Multilayers of 10. .. 50 periods have been synthesized. Soft X-ray measurements in the EUV-range at near normal incidence show reflectivities R of typically 60%. From HRTEM, a high stack regularity and minimum interface roughness can be s deduced. In contrast to conventional technologies (coating by sputtering or e-beam evaporation) the formation of a MoSi-interface layer happens only when depositing Mo on Si. Extremely sharp interface transitions from one individual x layer to the other are observed and the total period is represented by a three-layer system. From TEM results, a structure model for PLD-prepared Mo / Si-multilayers has been deduced. The optical parameters of the layers were adapted by reflectivity curve fitting, so that the results measured in the EUV-range can be explained. Using this model, predictions of the ratio of the number of atoms N /N for the total stack were made and are in good agreement with results of RBS Si Mo measurements. The use of the multilayers as X-ray optics requires an excellent homogeneity of the layer thickness across the entire mirror. It can be shown that the PLD technique is able to realize film uniformities with a standard deviation of the period thickness of less than 0.5%. This was confirmed by Cu-Ka-reflectometry and by near normal incidence measurements in the EUV range on 4 in. samples.

AIP Conference Proceedings

The synchrotron-based reflectometer at beamline 6.3.2 of the Advanced Light Source (ALS) in Berkeley is an important metrology tool within the current Extreme Ultraviolet Lithography (EUVL) program. This program is a joint activity of three National Laboratories and a consortium of leading semiconductor manufacturers. Its goal is the development of a technology for routine production of sub-100 nm feature sizes for microelectronic circuits. Multilayer-coated normal-incidence optical surfaces reflecting in the Extreme Ultraviolet (EUV) spectral range near 13 nm are the basis for this emerging technology. All optical components of EUV lithographic steppers need to be characterized at-wavelength during their development and manufacturing process. Multilayer coating uniformity and gradient, accurate wavelength matching and high peak reflectances are the main parameters to be optimized. The mechanical and optical properties of the reflectometer at ALS beamline 6.3.2 proved to be well suited for the needs of the current EUVL program. In particular the facility is highly precise in its wavelength calibration and the determination of absolute EUV reflectance. The reproducibility of results of measurements at ALS beamline 6.3.2 is 0.2 % for reflectivity and 0.002 nm for wavelength.

Emerging Lithographic …, 2000

Approved for public release; further dissemination unlimited DISCLAIMER This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author. This report has been reproduced directly from the best available copy.

Emerging Lithographic Technologies IV, 2000

Approved for public release; further dissemination unlimited DISCLAIMER This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author. This report has been reproduced directly from the best available copy.