Fluid dynamic assembly of semiconductor blocks for heterogeneous integration

We have studied the fluidic assembly (FA) technique for heterogeneous integration. In this technique, device blocks, the size of which ranges from a few tens of microns to a few hundreds of microns, are arranged onto another material substrate in fluid. Here, we propose a novel technique to improve FA, called fluid dynamic assembly (FDA), which employs fluid dynamic effects. In the FDA, a special structure is fabricated on the block, which stabilizes the posture of the blocks falling in the fluid. This can be used to control the face of assembled blocks. In this paper, the feasibility of the FDA is discussed on the basis of fluid dynamic simulation and experiments. The numerical simulations revealed that the face control can be carried out for the block having ringlike (O-type) structures on it. Then we carried out the FDA experiments using thin disk-shaped GaAs blocks with O-type structure, and demonstrated an 87% face control ratio for the blocks with 7.5-mum-thick structure. Moreover, the less symmetric C-type structure was examined, and demonstrated even a high face control ratio of 96%.