Anodic silicon etching; the formation of uniform arrays of macropores or nanowires

Macropore formation on p-type Si in the dark has been studied on 6-inch wafers in aqueous HF solution. More than 10⁹ pores with a diameter of 2.5 μm and a depth of 100 μm are obtained in a single etch step. These pores can be used as a template for the fabrication of high-density MOS capacitors. If the current density is close to the characteristic peak for the anodic etching of Si in HF solutions, nanowires are obtained. The length of these wires can reach values up to 100 μm, while their width can be as small as 30 nm. This method is a suitable way to the high-volume production of nanowires.