title: Formation of through-holes in Si wafers by using anodically polarized needle electrodes in HF solution.
abstract: Electrochemical pore formation in Si using an anodized needle electrode was studied. In the electrochemical process, a Pt, Ir or Pd needle with a diameter of 50-200 μm was brought into contact at its tip with a Si wafer, which was not connected to an external circuit, in HF solution. By applying an anodic potential to the needle electrode against a Pt counter electrode, a pore with a diameter slightly larger than the diameter of the needle electrode was formed in both p-type and n-type Si, of which current efficiency was higher for n-type Si. Through-holes were electrochemically formed in p-type and n-type Si wafers at speeds higher than 30 μm min(-1) using a sharpened Ir needle electrode. A model was proposed to explain the results, in which the pore formation was attributed to successive dissolution of Si atoms near the 3-phase (Si/metal/HF solution) boundary by positive holes injected from the needle electrode to the surface of Si.
authors.affiliation: Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Sugita
authors.forename: Chia-Lung
authors.initials: CL
authors.lastname: Lee
authors.forename: Shigeru
authors.initials: S
authors.lastname: Ikeda
authors.forename: Michio
authors.initials: M
authors.lastname: Matsumura