STMicroelectronics today unveiled the first details of a breakthrough technology that significantly increases junction capacitance density in thin-film passive integration.
The new technology greatly extends the capabilities of ST’s world-leading IPAD (Integrated Passive and Active Devices) technology by allowing capacitors with densities of more than 30nF/mm2 to be integrated, which represents a 50-fold improvement over existing competitive technologies that employ materials such as oxides or nitrides of silicon or tantalum.
The new technology is based on a class of materials called PZT Perovskites. Essentially, these are compounds that contain 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 over two hundred times greater than that of silicon dioxide. Equally importantly, they can be integrated cost-effectively into the proven, high-volume IPAD manufacturing flow.
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. For example, a typical mobile phone requires several hundred passive components, over half of which are capacitors. ST’s 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. ST’s new PZT technology represents a major breakthrough in integrating the higher value capacitors that are typically required for decoupling and low-frequency filtering purposes.
This will bring considerable benefits to customers by enabling 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 IC’s.
STMicroelectronics invented IPAD technology and is a leading supplier of IPAD devices worldwide. The new PZT technology will increase this leadership by allowing more integration and much better frequency behaviour as a result of reduced parasitic effects achieved by removing the SMD packages used today and designing shorter PCB interconnections.
To date, ST has used this technology for a number of customer-specific devices and will shortly introduce standard devices for the open market, when it will also release further technical details.
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