tailieunhanh - Smart Material Systems and MEMS - Vijay K. Varadan Part 11

Tham khảo tài liệu 'smart material systems and mems - vijay k. varadan part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Polymeric MEMS Fabrication Techniques 299 Electrolyle Anode a Insulator b Blanket-depsosited 2nd material e d Selectively deposited 1st Substrate material g Structural material Sacrificial support material Figure The EFAB process a electroplating through an instant mask b instant-mask removal c blanket deposition of the structural material d planarization by polishing e repetition of electroplating blanket deposition and planarization until the final structure is formed f remove of the sacrificial materials g cross-sectional view of one layer consisting of structural material and sacrificial materials 55 . A. Cohen G. Zhang F Tseng U. Frodis F. Mansfeld P. Will EFAB rapid low-cost desktop micromachining of high aspect ratio true 3-D MEMS Proc. IEEE MEMS 99 1999 IEEE of insulator patterned on a flat Cu disk. In selective electroplating pressure is applied between the Cu anode with the mask and the Ni substrate cathode . Blanket deposition is also based on the electroplating technique but without a mask. Basically the blanket-deposited material . Ni is different from the selective plated one Cu so that one of them acts as the sacrificial material and could be removed later. The planarization is done by lapping the surplus materials to achieve a precise layer thickness and flatness before deposition of the subsequent layer. By repeating the above steps a metallic 3-D microstructure can be formed Figure . The EFAB process is in its development stage. The resolution obtained is around 25 pm and the smearing caused by lapping and misregistration also affects the fabrication precision. Moreover the fabrication speed is a concern since too many time-consuming electroplating steps are involved although a throughput of two planarized 5 mm layers per hour or about 50 layers per day was anticipated 55 . Localized electrochemical deposition A localized electrochemical deposition apparatus is schematically shown in Figure 53 . The tip of a sharply .