Extension of a multilayer interconnection technology in MCM-Si with opto-electronic facilities

The increasing I/O-density of today's packages is dealt with by using multi layer modules. Since there is also a trend towards faster interconnections by using optics, the extension of the interconnection module with V-grooves is in high demand. This paper reports on the electro-optical extensions of an earlier developed standard MCM-Si technology (Lernout et al., Journal o f IMAPS (Europe) 1998; 15(1): 39-42; Ref. 1). The technology aspects of thi s standard MCM-Si technology are presented. The extended thin-film multilayer module is built up using two metal and th ree insulator layers. Additionally an implementation with low TCR resistors (NiCr) can be made. Fiber holding structures, namely V-grooves, an created into the bulk (100) silicon substrate by means of an anisotropic etching, performed in aqueous KOH. A passivation layer of silicon nitride, optimised towards low silicon content, served as protection mask during the KOH etch ing. The compatibility of this aggressive wet etching step with other proce ssing steps is discussed. As for the insulators in the multilayer module, t hese high quality PECVD (Plasma Enhanced Chemical Vapour Deposition) layers are optimised towards low stress content and uniformity. Subsequently, the use of this interconnection substrate as a motherboard in multichip modules (MCM) is considered. The extension of the motherboard wi th V-grooves makes it possible to integrate opto-electronic (O/E) component s, fibers and electronics on the same MCM-Si. Some of the major advantages are: low cost solution (saving non-used silicon area), compact assembly (ca rriers of fibers integrated with electronics), ability to reach higher freq uencies (shorter interconnection distances),... Also low coupling losses be tween laser and fiber are achieved: the accuracy of V-grooves in silicon pe rmits to place the fiber with high precision, and the self-aligning propert y of solder assures the control over the flip-chip (FC) mounted O/E-compone nts (e.g. laser diodes). (C) 2000 Elsevier Science Ltd. All rights reserved .