IMEC: RF-Sip: Microwave MCM-D technology

The multilayer thin-film technology (MCM-D) as developed over the past years, is well suited for high-frequency applications, particularly due to its high-precision definition and the possibility to integrate resistive and capacitive layers. The main features of IMEC’s thin-film technology are the use of electroplated copper for the interconnection lines, photo-sensitive benzocyclobutene (BCB) for the dielectric layers and Ni /Au for the final contact metallization. Up to 4 metal layers are used. The minimum copper line width and spacing are 5µm. Furthermore, a TaN resistor (25/square), Ta2O5 capacitor (0.75 nF/mm2) layer is integrated, lower value capacitors (5.6 pF/mm2) may be realized using the different BCB-layers.

Figure 1 : Schematic crossection of the microwave thin film builtup

The frequencies of interest vary from 1 to 50 GHz. The possibility of using multiple metal layers and our choice for a co-planar design style, offer a new dimension to the design of microwave circuits. An extensive microwave design library was developed for this technology. The library is integrated in the Agilent ADS microwave design suite and all models are validated up to 50GHz. This enables the microwave designer to efficiently and accurately design microwave circuits, also those including active devices. The library is coupled to an automatic layout generator, which allows a smooth and interactive mask realization as well as an automated design-rule check  (DRC).

RF MCM modules are formed by thin film deposition of metals on deposited dielectrics, which may be polymers or inorganic substrates. RF MCM provides a number of signi­ficant advantages over the previous technologies, mainly due to the fact that it uses processing techniques that are closely related to standard IC fabrication techno­lo­gies. The technology offers good dimensional control, small dimensions can be accura­tely realised, it offers a high reliability and passives (inductors, resistors and capaci­tors) can be easily integrated into the substrate.  Many integrated passive functions up to V-band have been demonstrated (see figure 2).

Figure 2 : Pictures of integrated passive devices integrated using an MCM- on AF45 glass technology from IMEC. left: bandpass filter at 5.2 GHz, right: integrated 50 GHz quadrature coupler.

Training on RF SiP