Selective deposition of copper in SiO2 trenches has been carried out using Pd/Si plasma immersion ion implantation and electroless Cu plating. To form the seed layer for electroless Cu plating on SiO2, sputtered Pd and Si atoms were partially ionized by the Ar plasma and then deposited at bottoms of SiO2 trenches; Ar ion beam was then applied to assist the mixing of the deposited Pd/Si films with the SiO2 substrate by recoil implantation. We found a threshold Pd dose of 2×1014/cm2 is required to initiate the electroless plating of Cu. By careful control of the anisotropic etching of the oxide trenches and proper choice of the Pd dose, 1-μm wide Cu filled lines with flat surfaces suitable for planarized multilevel metallization were successfully fabricated.
A novel magnetically actuated 8 8-port MEMSbased fiber-optic switch is described. Fiber-to-fiber insertion loss measurements of six 8 8 switch units show average and worst-case insertion loss of 1.3 dB and 2 dB, respectively. Low insertion loss is achieved through a unique MEMS design that uses anisotropically etched single-crystal silicon sidewalls to provide a global mechanical alignment stop for an array of MEMS mirrors. This alignment surface produces a uniform and repeatable mirror angle across the mirror array. Mirror misalignment is attributed to the surface roughness of the silicon sidewalls. Repeated interferometric measurements of the mirrors of 24 8 8 switch units show repeatability of the mirror angle of 3 10 3 degrees, while the uniformity of the mirror angle across the MEMS array is2 10 2 degrees, in agreement with the angular error predicted from measurements of sidewall surface roughness. In turn, the average repeatability and uniformity of the insertion loss are 0.01 dB and 1 dB, respectively, in agreement with predictions based on the interferometric measurements. Finally, the unique dynamics of the magnetic actuation and electrostatic addressing scheme are described. Measurements show that fast switching can be achieved by driving the mirrors with a magnetic pulse that is faster than the mechanical resonant frequency of the mirror, relying on an electrostatic clamping force to capture the mirror as it overshoots the magnetic field angle. This actuation scheme is shown to result in switching times of 8.5 ms to 13.5 ms, but requires accurate control of the kinetic energy of the mirror.[1169]Index Terms-Microelectromechanical devices, optical fiber devices, optical switches.
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