Multilevel nanoimprint lithography with submicron alignment over 4 in. Si wafers

We demonstrate that multilevel nanoimprint lithography (NIL) with submicron alignment over an entire 4 in. Si wafer can be achieved. Average alignment accuracy of 1 μm with a standard deviation 0.4 μm in both X and Y directions was obtained in ten consecutive tests of multilevel NIL. The multilevel alignment was achieved by aligning the wafer and the mask with an aligner, fixing them with a holder, and imprinting in an imprint machine. The issues that are critical to the alignment accuracy, such as relative movement during the press, relative thermal expansion, wafer bending, and resist, are discussed. The alignment accuracy currently achieved on the system is limited by the aligning accuracy of the aligner, instead of the process of multilevel NIL.