Flexible Circuits By The Slice

Researchers have demonstrated a way to make high-performance, flexible integrated circuits mainly via standard fabrication equipment and materials (Nano Lett., DOI: 10.1021/nl302735f). The process could lead to the creation of smart medical implants and flexible displays, without significantly overhauling current production protocols. The method, developed by Sanjay Banerjee of the University of Texas, Austin, and colleagues, begins with researchers patterning integrated circuits on 600- to 700-µm-thick silicon wafers. Next, they electroplate the patterned wafer with a 50- to 100-µm-thick layer of nickel and then heat the wafer to about 100 ºC. As the wafer is heated, silicon and nickel expand at different rates, putting stress on the silicon. As a result, the silicon wafer cracks at its edges about 20 to 30 µm below the surface. Then the team removes the nickel, leaving behind a thin, flexible platter of circuits that they cut up into 20- to 30-µm-thick chips.