Integrated Optics in a Standard MCM-D Motherboard Technology Demonstrated in O/E Measurement Probes

An ongoing trend in packaging technology is the introduction of optical interconnections to cope with the problems of increased data transmission speed and the raised interconnection density. Hence, improving packaging and interconnection technologies is only viable if the aspects of optical interfaces and opto-electronic (O/E) components are considered. In this paper, we will demonstrate an MCM-D technology with O/E features. We achieved to integrate high-precision V-grooves for alignment and fixation of the optical fibers into a standard MCM-D technology. The V-groove shape of the fiber fixation structures is a result of the anisotropic etching of (100) silicon by means aqueous KOH. The technology aspects of this aggressive wet etching step are discussed as well as the optimisation results of a suitable KOH masking layer: a low refractive index PECVD nitride. The extension of an MCM-D technology with V-grooves generates the possibility to integrate side-emitting O/E components and fibers with the electronics on the same MCM-Si motherboard. This implies a more dense and compact motherboard with the potential of obtaining higher bandwidths due to the minimal distance between optics and electronics. Additionally, low coupling losses between O/E components and fibers are obtained by means of passive alignment as the accuracy of the V-grooves in silicon allow us to place the fibers with high precision. The feasibility of this optics-extended MCM-D technology will be shown in the example of O/E measurement probes. In the fabrication process of such O/E measurement probes, we will focus on the multilayer MCM-D motherboard extended with V-grooves, on the FC mounting of both RF-amplifier chip and laserdiode, and on the alignment of the fiber.