DARWIN Digitale Dissertationen German Version Strich

FU Berlin
Digitale Dissertation

Viola Kirchner :
Electrochemical Microstructuring with Ultrashort Voltage Pulses
Elektrochemische Mikrostrukturierung mit ultrakurzen Spannungspulsen

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|Abstract| |Table of Contents| |More Information|

Abstract

Abstract of Thesis

Abstract

The fabrication of microstructures is one of today's key technologies. Applications of microdevices range from sensors and electronic devices up to complete miniaturized machines. In this thesis, a new electrochemical method is presented, which enables the three-dimensional machining of conducting materials with sub-micrometer precision. Electrochemical reactions on electrode surfaces are localized due to the application of ultrashort voltage pulses of only nanosecond duration.

      The method is based on the fact that the charging time constant of the double layer capacity varies linearly with the separation between the electrodes. During ultrashort pulses, effective charging is limited to electrode regions with distances below a few micrometers to the counter electrode. Since electrochemical reaction rates are exponentially dependent on the potential drop in the double layer, the reactions are sharply confined to these regions.

      Upon application of ultrashort voltage pulses to a tool electrode material can be locally etched or deposited. A tiny tool electrode can be etched into a workpiece or used like a miniature milling cutter. Thus, microstructures can be fabricated with a precision better than 1 mm and with high aspect ratios. With properly shaped tool electrodes it is possible to machine undercuts and freestanding elements into the material in one step.

      Micromachining with ultrashort voltage pulses is demonstrated for the local etching of copper, silicon, and stainless steel. The machining proceeds without inducing mechanical or thermal stress. Therefore, during etching, the material properties and the microcrystalline composition remain unchanged. In addition to local etching, the local deposition of copper structures is possible.

 

Table of Contents

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Inhaltsverzeichnis der Dissertation  

Titel und Inhalt


 
1 Einleitung   1
 
2 Die Idee   9
 
3 Experimentelles   23
  3.1 Aufbau   25
  3.2 Bipotentiostatische Regelung   26
  3.3 Herstellung der Werkzeuge   29
  3.4 Probenpräparation   32
  3.5 Experimentelle Durchführung   34
 
4 Mikrostrukturierung von Kupfer   37
  4.1 Experimentelle Bedingungen   37
  4.2 Dreidimensional geätzte Mikrostrukturen   39
  4.3 Lokale Kupferabscheidung   45
 
 
5 Mikrostrukturierung von Edelstahl   51
  5.1 Elektrochemische Besonderheiten   52
  5.1.1  Passivität und Passivschichten   53
  5.1.2  Bedingungen für die Mikrostrukturierung   58
  5.2 Mikrostrukturen   67
 
6 Mikrostrukturierung von Silizium   79
  6.1 Besonderheiten der Elektrochemie von Silizium   80
  6.1.1  Phasengrenze an Halbleiterelektroden   80
  6.1.2  Anodisches Ätzen von Silizium   84
  6.1.3  Bedingung für die elektrochemische Mikrostrukturierung   89
  6.2 Mikrostrukturen   91
 
7 Quantitative Untersuchungen   97
  7.1 Eindimensionale Simulation   98
  7.2 Zweidimensionale Simulation   104
  7.3 Experimente zur Ortsauflösung   108
  7.4 Wie gut kann die Methode werden?   118
 
8 Vergleich mit anderen Methoden   121
 
9 Zusammenfassung   127
 
Literaturverzeichnis   131
 

More Information:

Online available: http://www.diss.fu-berlin.de/2002/7/indexe.html
Language of PhDThesis: german
Keywords: Micromachining, Microstructuring, Electrochemistry, Voltage Pulses, Stainless Steel, Silicon
DNB-Sachgruppe: 30 Chemie
Date of disputation: 18-Dec-2001
PhDThesis from: Fachbereich Biologie, Chemie, Pharmazie, Freie Universität Berlin
First Referee: Prof. Dr. Gerhard Ertl
Second Referee: Prof. Dr. Helmut Baumgärtel
Contact (Author): kirchner@fhi-berlin.mpg.de
Contact (Advisor): ertl@fhi-berlin.mpg.de
Date created:14-Jan-2002
Date available:16-Jan-2002

 


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