Direct Microrolling Processing on a Silicon Wafer.

Although, varieties of micro- to nanoscale fabrication technologies have been invented and refined for silicon (Si) processing because Si is the basic material of integrated circuits, the layouts are based on layer-by-layer approaches, making it difficult to realize three-dimensional (3D) structures with complicated shapes normal to the planar surface (along the out-of-plane direction) of the wafers used. Here, a novel and direct Si-processing technology that enables to bend thin layers of Si surfaces into various 3D curved structures at the micrometer scale is introduced. This bending is achieved by porosifying a Si wafer surface using anodic oxidation and then performing conventional photolithography patterning and wet etching.