Shapeable Material Technologies for 3D Self-Assembly of Mesoscale Electronics (original) (raw)

Advanced Materials Technologies

simple transistors and logics to highly integrated microcontrollers and displays, the latter of which utilizes some of the most technologically advanced processes available in the industry. [3] The success of these technologies has been achieved through enhanced integration of various active functional blocks such as transistors, digital logics, and analog circuits, along with advances in miniaturization and simplification of the overall manufacturing process, eventually leading to large scale, parallel fabrication of silicon chip-based microelectronic components and systems. [4,5] However, many of the manufacturing steps in assembling these electronic components remain either semiparallel or sequential in nature, including processes as dicing, pick and place, packaging, and final assembly of the device. Each additional sequential step increases costs and should ideally be avoided, however substantial streamlining is not always feasible in complex manufacturing processes. [6] More critically, highly integrated silicon-based devices still require several external supporting components for their operation such as wiring, powering, sensing, and communications that cannot be easily integrated within the planar surface of a silicon die. Thus, sensors, actuators, capacitors, coils, antennas, and optics, each crucial for the complete system, are typically placed separately from the silicon chip onto a printed circuit board (PCB), or integrated within another package (Figure 1a). While the need for ever decreasing sizes has demanded tremendous investments and efforts in the manufacture of completed assemblies, the miniaturizing of 3D electronic components (Figure 1b) and systems has nevertheless reached the range of mesoscopic sizes (<1 mm) where the manufacture and assembly of components experience challenges with respect to yield, costs, and reliability. [7] As a result, these issues limit the fabrication potential and commercial viability of components and systems to scales around 1 mm, [8] and despite efforts to improve the planar construction of mesoscopic 3D devices, the results are seen as inefficient and experience difficulties in achieving high performances while maintaining reasonable complexity. Despite the great success in manufacturing active electronics, such concerns are strongly related to the fabrication of passive electronic components like inductors, capacitors, antennas, and resonators where material properties (e.g., mechanical, magnetic, and electrical) and geometry play a crucial role. [8,9] In order to downscale these devices further and improve integration with active electronics, novel fabrication strategies are required. Electronic devices and their components are continually evolving to offer improved performance, smaller sizes, lower weight, and reduced costs, often requiring the state-of-the-art manufacturing and materials to do so. An emerging class of materials and fabrication techniques inspired by self-assembling biological systems shows promise as an alternative to the more traditional methods that are currently used in the microelectronics industry. This spatial self-assembly process offers the possibility of improved performance while reducing overall manufacturing complexity of devices and components by harnessing the relative ease in which it can produce mesoscopic 3D geometries. These benefits can lead to tighter integration, reduced costs, and ultimately even small, autonomous robots fabricated from a single wafer. To better understand the technology, existing work in this research field is reviewed with regard to the mechanisms involved in the 3D self-assembly, the materials that facilitate it, and the devices that can benefit most from their implementation.