Trends in Microelectronic Systems Integration: From System on a Chip to System in a Package

The continued shift towards the integration of diverse functions into single chips and chip assemblies requires a new vision in microelectronic systems integration. Over the last decade or so, there has been a tremendous push towards systems on chip (SoC) approach for increased functionality. While systems on a chip has received much deserved credit for the size and cost reduction of many products, a true system on a chip solution has not been practical for a number of applications. In some cases, this is simply an issue of chip size, in others material compatibility (Si and GaAs), in yet others electrical compatibility (high voltage, RF, analog, with digital) and in some others the overall cost of integration on silicon, even if technically feasible. The need to combine diverse materials and technologies to achieve increased functionality with decreased size and weight, along with the ever present pressure for lower cost, has created the opportunity for new system level integration opportunities. Among the new concepts, system in a package (SiP) and system on a substrate (SoS) have received the most attention. System in a package is a natural extension of system on a chip concept. Currently, there are aggressive programs to develop SiP capabilities to allow rapid, cost effective design and fabrication of subsystem level packages. System on a substrate is an emerging concept based on the integration of technologies in a wide area of electronics. SoS will take the next step to the full system level (e.g. a monolithic radio). However, there is another important concept that seeks the same objective of system-level integration, but with a different set of drivers. In situations where the product is required to be a certain size (e.g. a display or a smart card), further size reductions of the components is no longer productive. This creates the opportunity for alternative technologies such as thin film transistors and plastic substrates. Integration of these technologies offers the potential for significant cost savings because of lower manufacturing costs, and light weight, wearable, flexible products by elimination of today's rigid substrates. Such technologies not only offer new capabilities, but also change the basic premise of the electronics industry. We could move from the microelectronics to the macroelectronics era. In this paper, we will present an overview of this diverse and emerging technology.