| AVS 60th International Symposium and Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS-TuP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | A.M. Lietz, University of Illinois at Urbana Champaign |
| Authors: | A.M. Lietz, University of Illinois at Urbana Champaign D. Curreli, University of Illinois at Urbana Champaign A.V. Hayes, Veeco A. Devashayam, Veeco D.N. Ruzic, University of Illinois at Urbana Champaign |
| Correspondent: | Click to Email |
Extreme UltraViolet Lithography (EUVL) requires reflective mask blanks, manufactured by ion beam sputtering a multilayer stack of thin films, primarily Mo and Si, onto a mask substrate. At least 40 bilayers of Mo and Si are necessary to produce a surface which has sufficient EUV light reflectivity for use in high volume manufacturing exposure tools. When contaminant particles deposit between these layers, the EUV light is absorbed or scatters irregularly, rendering the mask blank unusable. One possible source of such particles is bombardment of shields in the deposition chamber by energetic particles scattered from the ion beam and target and “overspill” of the tails of the ion beam off the edge of the target under oblique target angle of incidence. Shields are used to cover targets that are not in use and prevent deposition or sputtering nearby surfaces and equipment. These shields must be able to accept many successive layers of deposition without flaking and forming particles of deposited material. They must also be able to withstand ion beam overspill bombardment, while forming a minimal amount of particles.
In order to evaluate improved shield materials and surface finishes, shield samples were placed under a broad angle ion beam and particles were collected on a witness plate. Shields of various materials and surface finishes were compared to determine the lowest level of particle formation. The total number of particles on the witness plates was quantified using laser scattering particle detection. Particle sizes and shapes were quantified with high resolution SEM imaging of the witness plate, and their composition was determined using backscattered electron imaging. The shield samples themselves were also analyzed using SEM to check for qualitative features, such as plateau formation, that may indicate the mechanism of particle formation.