Silicon-based passive devices for applications up to GHz-frequency range
Techniques related with abbreviations like PiP, SiP, PIC, MCM etc. indicate that passive devices in systems are still of importance. As well increasing process complexity in technology migration towards deep submicron stimulates a System-on-Chip (SoC) versus System-in-Package (SiP) discussion for systems including passive elements. Passive devices are today mainly based on ceramic substrates and assembled into packages, modules or systems as discrete elements. Future integration concepts ask for reduction of system integration space and subsequent e.g. for chip-stacking. Silicon based passive devices can support an "all-components-on-silicon" concept. Therefore lateral- and trench-type capacitors have been investigated. The results of first research wafer runs show good electrical characteristics concerning e.g. breakdown voltage and Q-factor up to GHz frequency range. Concerning trench-type capacitors the reduction of the equivalent series resistance was addressed by t he development of an innovative metal-filled trench process. As a third topic a basic study was done in the area of micro inductors. The focus of the study was set on lithography of thick film material. The results show feasibility of micro inductors on silicon substrate. Due to some arising but solvable challenges in process details the complete fabrication of demonstrator devices was identified to be subject of a future project preferably in cooperation with industry.