How to make single small holes with large aspect ratios

• Published in: Physica status solidi. PSS-RRL. Rapid research letters Vol. 3; no. 2-3; pp. 55 - 57
• Main Authors: Föll, Helmut, Gerngroß, Mark-Daniel, Cojocaru, Ala, Leisner, Malte, Bahr, Jörg, Carstensen, Jürgen
• Format: Journal Article
• Language: English
• Published: Berlin WILEY-VCH Verlag 01-03-2009; WILEY‐VCH Verlag
• Subjects: 81.05.Rm; 82.45.Mp; 82.45.Qr; 82.45.Vp; 82.47.Wx; 85.85.+j
• ISSN: 1862-6254; 1862-6270
• DOI: 10.1002/pssr.200802257

In many areas of research a need for single small holes with diameters from a few nm to several μm and large aspect ratios exists that is hard to meet with existing technologies. In a proof of principle it is shown that suitable single holes or specific arrays of some single holes can be made by first etching a very large number of small and deep holes or pores into semiconductors like Si or InP by established electrochemical means, followed by masking the desired holes and filling all others with, e.g., a metal in a galvanic process. The potential and limitations of this technique is briefly discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High aspect ratio single holes or single hole arrays can be produced in n‐type and p‐type silicon by the subsequent application of standard electrochemical processes: (i) Etching an array of macropores. (ii) Sealing specific pores by toner particles. (iii) Electrodeposition of a metal into the pore array. (iv) Grinding of the pore back side to transform pores into long holes.