Wafer-level vacuum sealing for packaging of silicon photonic MEMS

Silicon (Si) photonic micro-electro-mechanical systems (MEMS), with its low-power phase shifters and tunable couplers, is emerging as a promising technology for large-scale reconfigurable photonics with potential applications for example in photonic accelerators for artificial intelligence (AI) workloads. For silicon photonic MEMS devices, hermetic/vacuum packaging is crucial to the performance and longevity, and to protect the photonic devices from contamination. Here, we demonstrate a wafer-level vacuum packaging approach to hermetically seal Si photonic MEMS wafers produced in the iSiPP50G Si photonics foundry platform of IMEC. The packaging approach consists of transfer bonding and sealing the silicon photonic MEMS devices with 30 μm-thick Si caps, which were prefabricated on a 100 mm-diameter silicon-on-insulator (SOI) wafer. The packaging process achieved successful wafer-scale vacuum sealing of various photonic devices. The functionality of photonic MEMS after the hermetic/vacuum packaging was confirmed. Thus, the demonstrated thin Si cap packaging shows the possibility of a novel vacuum sealing method for MEMS integrated in standard Si photonics platforms

Vacuum-sealed silicon photonic MEMS tunable ring resonator with an independent control over coupling and phase

Ring resonators are a vital element for filters, optical delay lines, or sensors in silicon photonics. However, reconfigurable ring resonators with low-power consumption are not available in foundries today. We demonstrate an add-drop ring resonator with the independent tuning of round-trip phase and coupling using low-power microelectromechanical (MEMS) actuation. At a wavelength of 1540 nm and for a maximum voltage of 40 V, the phase shifters provide a resonance wavelength tuning of 0.15 nm, while the tunable couplers can tune the optical resonance extinction ratio at the through port from 0 to 30 dB. The optical resonance displays a passive quality factor of 29 000, which can be increased to almost 50 000 with actuation. The MEMS rings are individually vacuum-sealed on wafer scale, enabling reliable and long-term protection from the environment. We cycled the mechanical actuators for more than 4 × 109 cycles at 100 kHz, and did not observe degradation in their response curves. On mechanical resonance, we demonstrate a modulation increase of up to 15 dB, with a voltage bias of 4 V and a peak drive amplitude as low as 20 mV.</jats:p

Wafer-level hermetically sealed silicon photonic MEMS

The emerging fields of silicon (Si) photonic micro–electromechanical systems (MEMS) and optomechanics enable a wide range of novel high-performance photonic devices with ultra-low power consumption, such as integrated optical MEMS phase shifters, tunable couplers, switches, and optomechanical resonators. In contrast to conventional SiO2-clad Si photonics, photonic MEMS and optomechanics have suspended and movable parts that need to be protected from environmental influence and contamination during operation. Wafer-level hermetic sealing can be a cost-efficient solution, but Si photonic MEMS that are hermetically sealed inside cavities with optical and electrical feedthroughs have not been demonstrated to date, to our knowledge. Here, we demonstrate wafer-level vacuum sealing of Si photonic MEMS inside cavities with ultra-thin caps featuring optical and electrical feedthroughs that connect the photonic MEMS on the inside to optical grating couplers and electrical bond pads on the outside. We used Si photonic MEMS devices built on foundry wafers from the iSiPP50G Si photonics platform of IMEC, Belgium. Vacuum confinement inside the sealed cavities was confirmed by an observed increase of the cutoff frequency of the electro-mechanical response of the encapsulated photonic MEMS phase shifters, due to reduction of air damping. The sealing caps are extremely thin, have a small footprint, and are compatible with subsequent flip-chip bonding onto interposers or printed circuit boards. Thus, our approach for sealing of integrated Si photonic MEMS clears a significant hurdle for their application in high-performance Si photonic circuits.QC 20220303MORPHICAEOLUSULISSESZeroAM

Large scale programmable photonic circuits using silicon photonic MEMS

We demonstrate low-power and non-volatile MEMS actuators on an industrially established silicon photonics platform. The compact electrostatically actuated phase shifters and tunable couplers enable large-scale programmable photonic integrated circuits

Wafer-level Hermetic Sealing of Silicon Photonic MEMS by Direct Metal-to-Metal Bonding

The field of silicon (Si) photonic micro-electromechanical system (MEMS) for photonic integrated circuits (PICs) has evolved rapidly. Thanks to the ultra-low power consumption of Si photonic MEMS, it enables a wide range of high-performance photonic devices such as integrated optical MEMS phase shifters, tunable couplers and switches. However, photonic MEMS have suspended and movable parts which need to be protected from environmental influences, such as exposure to dust and humidity. Therefore, a packaging solution is needed for reliable operation over long periods. Here, we demonstrate wafer-level vacuum sealing of Si photonic MEMS inside cavities with ultra-thin Si caps.QC 20221214MORPHIC (EU, H2020)ZeroAMP (EU, H2020)ULISSES (EU, H2020)AEOLUS (EU, H2020

Programmable photonic circuits using silicon photonics MEMS

We present a silicon photonics technology extended with low-power MEMS scalable to large circuits. This enables us to make photonic waveguide meshes that can be reconfigured using electronics and software