The objective of this work is to develop a silicon integrated microcapacitor with an enlarged electrode area, suitable for high energy storage in powering advanced microsystems. That enlargement has been obtained by anodizing the semiconductor, which results in the formation of macroporous structures with an aspect ratio between 10 and 100, in both P and N type silicon.

An electrochemically etched <100> P type substrate ensures a vertical growth of silicon macropores, due to its crystalline orientation. The pore density increases with the anodization current density, which also has an increasing effect over the growth rate, in a certain electrolyte. The relationship between the mentioned parameters has been analyzed by the use of image processing software and Scanning Electron Microscopy (SEM).

Starting from a N type silicon wafer, back side illumination is required to ensure the desirable vertical growth of the macropores, according to the <100> crystalline orientation and towards the source of electric holes. An Indium Tin Oxide (ITO) thin film has been deposited on the back side, as an ohmic contact, allowing the wafer being illuminated. A high transmittance of the deposited film and a resistivity as low as 3x10^-4 ohm.cm have been obtained. The properties of the ITO layer grown under different process parameters have been characterized by a spectrometer, X-ray Diffraction (XRD) and a Sheet Resistance Monitoring System.

The local formation of porous silicon has been delimited by regions highly doped with phosphorous, which endure against the electrochemical etching. A dry thermal oxidation of the substrate constitutes the dielectric layer of the capacitor. The top electrode has been built by a homogenous polysilicon layer grown by the Low Pressure Chemical Vapor Deposition (LPCVD) technique, which has been characterized by Field Emission Gun SEM and RXD. A doping process with phosphorous at 1000 ºC reduces the electrode sheet resistance up to 3 ohm/sq.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/11546 must be provided.