Conformal coatings for 3D multichip microsystem encapsulation

Materials and methods for low cost minimum volume protective encapsulation of microsystems have been investigated. The focus has been on a 3D conformal multilayer coating of silicon microphones. Materials with different properties, e.g. insulating and conductive, can be applied and combined as multilayers around the sharp edges of single crystalline silicon giving a protection which can not be matched by a single material. A 50 mum thick insulating layer with volume resistivity above 10(16) Ohm cm with a 150 mum thick conductive layer on top is reported to have an EMI E-field damping higher than 55 dB in the 50 MHz-1 GHz frequency range.