Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Accuracy of Microcontact Printing Alkanethiols on Gold: Reducing Unwanted Mass Transport of the Ink

IP.com Disclosure Number: IPCOM000122879D
Original Publication Date: 1998-Jan-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 4 page(s) / 132K

Publishing Venue

IBM

Related People

Biebuyck, H: AUTHOR [+4]

Abstract

Microcontact printing (&mu.CP) is a technique that uses an inked stamp, usually an elastomeric polymer, to transfer an ensemble of molecules in the ink as a chemical pattern onto a substrate (1). The technique is currently mostly used to pattern gold substrates with linear alkanethiols because these molecules self-assemble into monolayers on gold and can protect this substrate from a 'CN' sup - '/O' sub 2-based etch in the printed regions (2). Thiols diffuse from the zones of contact between the stamp and the substrate or from the walls of the cavities where the stamp does not contact the substrate. This diffusion is highly detrimental to the resolution of the &mu.CP technique by derivatization, and subsequently protection against etchants, of the substrate outside the zones of the print.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Accuracy of Microcontact Printing Alkanethiols on Gold:  Reducing
Unwanted Mass Transport of the Ink

      Microcontact printing (&mu.CP) is a technique that uses an
inked stamp, usually an elastomeric polymer, to transfer an ensemble
of molecules in the ink as a chemical pattern onto a substrate (1).
The technique is currently mostly used to pattern gold substrates
with linear alkanethiols because these molecules self-assemble into
monolayers on gold and can protect this substrate from a 'CN' sup -
'/O' sub 2-based  etch in the printed regions (2).  Thiols diffuse
from the zones of contact between the stamp and the substrate or from
the walls of the cavities where the stamp does not contact the
substrate.  This diffusion  is highly detrimental to the resolution
of the &mu.CP technique by derivatization, and subsequently
protection against etchants, of the substrate outside the zones of
the print.

      A solution against unwanted diffusion of the ink is, therefore,
important to help &mu.CP remain an accurate pattern transfer
technique.  A solution to this problem is proposed that changes the
physical characteristics of the ink.  Two important parameters of
&mu.CP, the concentration of the thiols in the ink and the duration
of the print, are key to improving the accuracy of &mu.CP.

      Fig. 1 shows etch patterns on a gold substrate printed with
stamps of similar geometry but inked with linear alkanethiols of
different lengths.  When the stamp was inked with a 0.5 mM solution
of dodecanethiol in ethanol, no pattern in the gold could be produced
following a 20 s print in the gold.  Vapor phase transport from the
receding regions in the stamp and diffusion from the zones of contact
evidently formed a protective monolayer everywhere.  Increasing the
molecular weight of the ink by using a longer alkanethiol,
Hexadecanethiol (HDT), reduced uncontrolled mass transport of the
chemisorbing molecules.  A pattern composed of elongated features in
the gold can be identified and is surrounded by a large number of
gold crystallites that survived the etch.  The control in the figure
indicates that gold &tilde.  5 &mu.m away from the stamp etched
perfectly under the conditions used here:  a 6 min etch in 0.1 M KCN
in a KCl/NaOH buffer (pH 12).  The control also...