Print Email Facebook Twitter 3D Align overlay verification using glass wafers Title 3D Align overlay verification using glass wafers Author Smeets, E.M.J. Bijnen, F.C.G. Slabbekoorn, J. Van Zeijl, H.W. Faculty Electrical Engineering, Mathematics and Computer Science Department Delft Institute of Micro Electronics and Submicron Technology Date 2004-12-30 Abstract In the MEMS world, increasing attention is being given to 3D devices requiring dual-sided processing. This requires lithography tools that are able to align a wafer to both its back side as front side. Overlay describes how well front and back side layers are positioned with respect to each other. Currently there is no simple and fast method to qualify the overlay. This paper covers a method of measuring the overlay between front- and back side patterns using a glass substrate. We describe the methods used, special process requirements and measurement data. The main advantages of the presented method are the simplicity of the concept and the need for only basic fab processing equipment. The substrate employed is re-usable and low cost. The results are as follows: 1. Glass wafers can be used to measure front to back side overlay. The accuracy of the proposed method is better than 100 nm (3?) on ASML PAS 5000/5200 machines. On ASML PAS 5500 steppers, the expected accuracy is better than 80 nm (3?). 2. The proposed method of measuring the absolute glass shift, from a glass-on-silicon stack, yields unreliable information. This is due to deformation of the glass. An alternative method is described which builds on result 1 (above). 3. Processing of glass wafers has been established, and a glass overlay measurement wafer has been defined. 4. The benefit of Anti Reflective (AR) coatings is suspected, but not yet proven. Minimizing bi-refringency does not play a role in the measurement accuracy of glass wafers for overlay measurements. Subject MEMSMOEMSFTBAoverlaylithography3D Align tmglass wafer To reference this document use: http://resolver.tudelft.nl/uuid:1d5db401-1410-4098-ad47-d29f7baa5519 Publisher SPIE ISSN 0277-786X Source Proceedings of SPIE, 2004 vol. 5641 Part of collection Institutional Repository Document type conference paper Rights (c)2004 Smeets, E.M.J., Bijnen, F.G.C., Slabbekoorn, J., Van Zeijl, H.W. Files PDF 3DSmeets.pdf 655.69 KB Close viewer /islandora/object/uuid:1d5db401-1410-4098-ad47-d29f7baa5519/datastream/OBJ/view