3D Integration of Flexible and Printed Electronics: Integrated Circuits, Memories, and Sensors

Abstract

Printing technologies have received a lot of attention and expectations for producing flexible and wearable electronics. However, the low transistor density of the printed devices has been a major obstacle to commercialization. In this review, a three-dimensional (3D) integration of organic flexible and printed electronics is described. First, layout-to-bitmap conversion and design rules for printed transistors, arrays, and integrated circuits are introduced. Then, printed 3D transistors, digital integrated circuits, and memories are described. Finally, 3D integration of printed active-matrix arrays and sensors is highlighted. This approach is a breakthrough technology that not only reduces the area occupied by a single transistor, memory, and sensor, but also increases the efficiency of routing, effectively reducing the area of the entire devices. In addition, monolithic 3D integration through the printing can stack transistor, memory, and sensor by simply repeating the additive process.