Electrothermal Actuators for SiO2 Photonic MEMS

This paper describes the design, fabrication and characterization of electrothermal bimorph actuators consisting of polysilicon on top of thick (>10 μ m ) silicon dioxide beams. This material platform enables the integration of actuators with photonic waveguides, producing mechanically-flexible photonic waveguide structures that are positionable. These structures are explored as part of a novel concept for highly automated, sub-micrometer precision chip-to-chip alignment. In order to prevent residual stress-induced fracturing that is associated with the release of thick oxide structures from a silicon substrate, a special reinforcement method is applied to create suspended silicon dioxide beam structures. The characterization includes measurements of the post-release deformation (i.e., without actuation), as well as the deflection resulting from quasi-static and dynamic actuation. The post-release deformation reveals a curvature, resulting in the free ends of 800 μ m long silicon dioxide beams with 5 μ m-thick polysilicon to be situated approximately 80 μ m above the chip surface. Bimorph actuators that are 800 μ m in length produce an out-of-plane deflection of approximately 11 μ m at 60 mW dissipated power, corresponding to an estimated 240 ∘ C actuator temperature. The delivered actuation force of the 800 μ m-long bimorph actuators having 5 μ m-thick polysilicon is calculated to be approximately 750 μN at 120 mW

Design, Fabrication and Testing of Assembly Features for Enabling Sub-micron Accurate Passive Alignment of Photonic Chips on a Silicon Optical Bench

Part 1: Micro Assembly Processes and SystemsInternational audienceIn this paper, we report on passive alignment with sub-micron precision of two photonic chips on a silicon optical bench. An effective design principle to minimize the tolerance chain is presented and applied to a case study. The chips have been successfully manufactured and individual characterization of the chips revealed that all critical dimensions were within or close to specs. Sub-pixel analysis of images of assembled chips showed that a repeatability of 0.3 μm from a single photonic chip to the silicon optical bench can be achieved. Moreover, it was demonstrated that passive alignment features defined in the waveguiding layers are robust enough to function as mechanical endstops

Towards reel-to-reel integration of ultra-thin chips to polymer foils

The EU FP7 funded project Chip2Foil aims to realise a technology platform allowing a radically different implementation of the assembly process for ultra-thin chips (UTCs) to polymer foils. The process is based on redistribution of the tolerance budget, and consists of two major steps: self-assembly supported chip placement followed by an adaptive circuitry approach for realising the electrical interconnects. The concept accepts non-contact, low precision presentation of a UTC to the self-assembly force field, which brings the chip to a final position with moderate precision. Next, in an adaptive interconnection process the chip position is measured with respect to the circuitry on the foil and interconnects are created on an individual chip and IO basis. The main technology building blocks are described and the current performance is demonstrated, including chip thinning, fast UTC release from wafer tape, self-assembly supported chip placement using magnetic forces and adaptive electrical interconnection by laser scribing of a screen-printed silver patch