摘要
This paper reviews an initial achievement of our group toward the development of on-chip parallel high-speed atomic force microscopy（HS-AFM）.A novel AFM approach based on silicon waveguide cantilever displacement sensor is proposed.The displacement sensing approach uniquely allows the use of nano-scale wide cantilever that has a high resonance frequency and low spring constant desired for on-chip parallel HS-AFM.The approach consists of low loss silicon waveguide with nano-gap,highly efficient misalignment tolerant coupler,novel high aspect ratio（HAR）sharp nano-tips that can be integrated with nano-scale wide cantilevers and electrostatically driven nano-cantilever actuators.The simulation results show that the displacement sensor with optical power responsivity of 0.31%/nm and AFM cantilever with resonance frequency of 5.4 MHz and spring constant of 0.21 N/m are achievable with the proposed approach.The developed silicon waveguide fabrication method enables silicon waveguide with 6 and 7.5 dB/cm transmission loss for TE and TM modes,respectively,and formation of 13 nm wide nano-gaps between silicon waveguides.The coupler demonstrates misalignment tolerance of ±1.8 μm for 5μm spot size lensed fiber and coupling loss of 2.12 dB/facet for standard cleaved single mode fiber without compromising other performance.The nano-tips with apex radius as small as 2.5 nm and aspect ratio of more than 50 has been enabled by the development of novel HAR nanotip fabrication technique.Integration of the HAR tips onto an array of 460 nm wide cantilever beam has also been demonstrated.
This paper reviews an initial achievement of our group toward the development of on-chip parallel high-speed atomic force microscopy（HS-AFM）.A novel AFM approach based on silicon waveguide cantilever displacement sensor is proposed.The displacement sensing approach uniquely allows the use of nano-scale wide cantilever that has a high resonance frequency and low spring constant desired for on-chip parallel HS-AFM.The approach consists of low loss silicon waveguide with nano-gap,highly efficient misalignment tolerant coupler,novel high aspect ratio（HAR）sharp nano-tips that can be integrated with nano-scale wide cantilevers and electrostatically driven nano-cantilever actuators.The simulation results show that the displacement sensor with optical power responsivity of 0.31%/nm and AFM cantilever with resonance frequency of 5.4 MHz and spring constant of 0.21 N/m are achievable with the proposed approach.The developed silicon waveguide fabrication method enables silicon waveguide with 6 and 7.5 dB/cm transmission loss for TE and TM modes,respectively,and formation of 13 nm wide nano-gaps between silicon waveguides.The coupler demonstrates misalignment tolerance of ±1.8 μm for 5μm spot size lensed fiber and coupling loss of 2.12 dB/facet for standard cleaved single mode fiber without compromising other performance.The nano-tips with apex radius as small as 2.5 nm and aspect ratio of more than 50 has been enabled by the development of novel HAR nanotip fabrication technique.Integration of the HAR tips onto an array of 460 nm wide cantilever beam has also been demonstrated.
