MEMS, MOEMS, RF-MEMS and photonics packaging based on LTCC technology

Abstract

In order to fulfill the specifications of photonic systems, various optoelectronic chips, MEMS, MOEMS and RF-MEMS devices, micro-optical elements and integrated circuits needs to be integrated into functional components, modules and systems. The sub-systems of the photonic system must be fabricated by the use of costefficient, reproducible, well-established, high-volume manufacturing technologies. The functionality of the system is outlined by the combination of the functionalities of individual devices. The performance of the system, however, is defined by packaging and integration methods and configurations. Low temperature co-fired ceramics (LTCC) is one of our key technology assets for photonics and MEMS/ MOEMS/RF-MEMS packaging. In photonics integration, the tolerance of device alignment is the key issue of integration. In order to be able to use mass-manufacturing tools, the primary aim is to process 3D structures, such as, grooves, cavities, holes, bumps and alignment fiducials, which can be used for the passive alignment of devices. The tolerances of LTCC structures are typically ±5µm and in some specific cases ±2µm. Therefore, LTCC provides means for the passive alignment of multimode fiber as well as MOEMS devices. Thermal management by the use of thermal vias in LTCC is a well-established technique, and liquid cooling channels in the LTCC substrate provide efficient additional means for high-power laser cooling. When targeting for thermally controlled systems, thermal bridge structures can be used to isolate critical devices from main structures. LTCC provides inherently hermetic substrate allowing for the possibility to hermetic encapsulation. Hermetic fiber feed throughs and transparent windows can be integrated in LTCC structures. Cavities, channels and sealed gas cells can be fabricated, also. RF antennas and coil structures for electro-magnetic field control can be integrated in the LTCC substrate. Therefore, 3D packaging of MEMS, MOEMS and photonic devices is enabled by LTCC.