Patent ID: 8802482

Claim:
A method for roughening a multi-crystalline silicon surface, comprising the steps of: coating the multi-crystalline silicon surface with a first diblock copolymer layer; annealing the first diblock copolymer layer to form nanopores therein; spin-coating one or more second diblock copolymer layers onto the first diblock copolymer layer, after the first diblock copolymer layer has been annealed, to form a stack of diblock copolymer layers on the surface of the multi-crystalline silicon substrate; annealing the one or more second diblock copolymer layers to form nanopores therein, wherein a number of the diblock copolymer layers employed in the stack is based on a desired nanopore spacing between the nanopores formed in the first diblock copolymer layer that line up with the nanopores formed in the one or more second diblock copolymer layers and thus provide through-extending nanopores in the stack which extend through both the first diblock copolymer layer and each of the one or more second diblock copolymer layers, and wherein by increasing the number of the diblock copolymer layers in the stack the nanopore spacing is increased since only a fraction of the nanopores formed in the first diblock copolymer layer will line up with the nanopores in each of the one or more second diblock copolymer layers; etching the multi-crystalline silicon surface through the through-extending nanopores in the stack to roughen the multi-crystalline silicon surface; and removing the first diblock copolymer layer and the one or more second diblock copolymer layers from the surface of the multi-crystalline silicon substrate.