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Geneva-based STMicroelectronics recently gave the first details of a breakthrough technology that significantly increases junction capacitance density in thin-film passive integration and extends the capabilities of ST¡¦s integrated passive and active devices (IPAD) technology by allowing capacitors with densities of more than 30nF/mm² to be integrated.



This breakthrough represents a 50-fold improvement over existing competitive technologies that employ materials such as oxides or nitrides of silicon or tantalum, ST noted.



ST¡¦s new technology is based on a class of materials called PZT Perovskites, which are compounds containing lead, zirconium, titanium and oxygen, with many different variations possible according to the ratio of zirconium and titanium.



These materials offer outstanding advantages because of their very high dielectric constant, which, at approximately 900 depending on the particular material, is more than 200 times greater than that of silicon dioxide. Equally importantly, they can be integrated cost-effectively into the proven, high-volume IPAD manufacturing flow, ST explained.



The integration of passive devices is of fundamental importance, especially in all nomadic applications where complex filtering and protection functions, which typically demand a large number of passive components such as resistors, capacitors and inductors, must be incorporated into equipment where PCB space is at a premium.



Given that a typical mobile phone requires several hundred passive components, over half of which are capacitors. ST said its IPAD technology allows large numbers of passive components to be integrated along with active devices such as ESD protection diodes into a single structure that performs a specified filtering or protection function.



A continual challenge in this type of integration is the search for new materials that allow ever increasing values of resistance or capacitance to be integrated. In the case of capacitors, the dielectric constant of the material is the most important factor because the capacitance is determined by the surface area, which it is always desired to minimize, and the dielectric constant.



As such, ST believes its PZT technology represents a major breakthrough in integrating the higher value capacitors that are typically required for decoupling and low-frequency filtering purposes, allowing a new level of system partitioning optimization in terms of size, performance, cost and time-to-market, as a single IPAD component can replace more than 30 discrete devices with one die that is compatible with flip-chip packaging technology or SiP assembly with ICs.



ST invented IPAD technology and said the PZT technology would allow more integration and much better frequency behavior as a result of reduced parasitic effects achieved by removing the SMD packages used today and designing shorter PCB interconnections.



The company has used this technology for a number of customer-specific devices and said it will soon introduce standard devices for the open market.