Thin Film Decoupling Circuits, Making Use of a Three-dimensional Integration of Thin Film Passive Components
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high capacitance density
lithographic patterning of electrodes and dielectrics 4 tight tolerances low temperature processing -) high integration potential
To realise high quality capacitors which are requested in the mobile communication market and electronic data processing market, thin film metal electrodes such as Cu, Al, Pt with smooth surfaces are applied on top of insulating substrates such as glass or A120 3. With the highly conductive metal layers such as Al, low ohmic losses of the capacitors of•_ 100 mohm at frequencies of 500 MHz up to 1.5 GHz can be achieved. On top of the thin film metal layers thin dielectric layers such as Si0 2 , SiN(H), Ta 2O5 , TiO 2 as well as Bal.,SrTiO 3, or lanthanum doped PbZrxTii.,O 3 with relative permittvities of 4-1100 are deposited. The dielectric layers are covered with a second metal layer. Pattering of the thin metal and dielectric 463 Mat. Res. Soc. Symp. Proc. Vol. 596 © 2000 Materials Research Society
layers by means of lithographic processes such as dry as well as wet-etching, offers capacitors with a high performances. Special features of the thin film capacitors are the tight tolerance of the capacitance values of only 1-2 %. INTEGRATED THIN FILM CAPACITORS
In the portable electronic industry small sized electronic circuits with low weight and low power consumption are requested. For that reason numerous groups evaluate new product concepts, which consider the integration of passive components into passive modules [8, 9, 10]. An attractive integration route with respect to component density makes use of thin film techniques. Thin film capacitors, resistors, inductors are grown next to each other on top of substrates such as silicon or A120 3 . The processing on top of Si-substrates offers the potential to integrate active devices such as diodes, which can act as ESD (electrostatic discharge)
protection for the circuits, into the substrate. A very flexible concept makes use of metalinsulator-metal (MIM) structures for the capacitors. The capacitors are formed from high purity thin metal layers such as Al or noble metal electrodes. Dielectric layers are SiN(H) for small capacitance values of a few pF up to some tenth of pF as well as ferroelectric thin films such as lanthanum doped PbZrTil.O 3 for large capacitance values of up to some tenth of nF. Thin film resistors are made from poly-Si, thin TiW(N) or NiCr layers. These types of planar thin film RC networks are especially applied for electromagnetic interference (EMI) suppression. Thin film passive networks grown on top of Si-substrates do not only integrate active devices such as protection diodes into the substrate. Passive networks on Si are also developed for Multi-Chip Modules (MCMs). Multichip modules with integrated passive components are reported by several groups. R. W. Schwartz et al. [I1] have grown PbZrjTil5 O 3 thin films on top of Si-substrates to integrate decoupling capacitors. Multi-chip modules with integrated decoupling capacitors have also been developed by T. Bland [12]. High
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