The Physics of Microdroplets

Chapter 11

Capillary Self-assembly for 3D Microelectronics

11.1 Abstract

Since the first microprocessor, fabricated in 1971, the performance of electronic chips has been rapidly increasing. The development speed has been following Moore’s law [1]. More precisely, Moore’s law describes a long-term trend in the history of computing hardware, in which the number of transistors that can be placed inexpensively on an integrated circuit has doubled approximately every two years. However, miniaturization limits – such as interconnect length and interference between packed electric circuitry – has recently brought limitations to the historical trend. Two axes of development are being investigated: the first one, called “more Moore,” consists of pursuing integration efforts to miniaturize ever further integrated circuit technology. The second one, called “more than Moore,” seeks to add functionalities to the integrated circuits, without further reductions in the dimensions.

In both cases, three-dimensional integration appears to be mandatory [2]. The conventional two-dimensional architecture presents horizontal wiring that slows down the transmission speed. Three-dimensional stacking of chips would result in shorter interconnects and consequently deliver a shorter transmission time. A required condition is a precise alignment of the chips – allowing for vertical connections – and a sufficiently strong direct bonding to vertically assemble the components. Another advantage of three-dimensional ...