(429f) A Novel Method of Making Stamps in Soft Lithography Via Compressed Carbon Dioxide

A
novel method of making stamps in soft lithography via compressed carbon dioxide

Yu Cang,
Rui Zhang*, Lixiao Liu, Jianchao Zhang, Tao Yang, Xuhong Guo*

State
Key Laboratory of Chemical Engineering, East China University of Science and
Technology, 130 Meilong Road, Shanghai 200237, China

*Corresponding
authors. Tel.: +86-21-64253491; E-mail: r.zhang@ecust.edu.cn

 guoxuhong@ecust.edu.cn

Abstract: Soft lithography (SL) is one
newly developed and high precise microfabrication technology which can
fabricate various microstructures of materials costless with the help of medium
pattern-transfer element or elastomeric stamp. Polydimethylsiloxane(PDMS)
owns excellent viscoelasticity that become widely used in making
different-microstructure stamps. PDMS stamps are produced by casting and curing
PDMS precursors on the Si master by photolithography or swelled by some organic
solvent traditionally. However, these preparation methods are expensive and may
distort microstructures which limited their applications.
We propose a new method of making stamp that imprint microstructure on PDMS
with compressed carbon dioxide due to the good solubility of PDMS in compressed
carbon dioxide. The patterns are sandwiched between two PDMS moldings under
certain pressure and temperature. We use gauze, silica gel particle and
nanometer-size chip as patterns. In the whole process, the reaction pressure is
up to 5MPa and temperature is 318.15K, which can soft
PDMS well. However, after the reaction the quench temperature should be
decreased obviously under constant pressure to prevent the collapse of stamp.
The patterns of different dimensions from micro-meters to nano-meters
can be imprinted perfectly after about 4 hours. The simply and precise way of
making stamp can expand the use of SL in chemistry, biology, physics,
semiconductor fields and so on.

Keywords:
soft
lithography, polydimethylsiloxane, carbon dioxide

Figure. (a) SEM
image of PDMS before imprinted (b) SEM image of gauze pattern (c) SEM image of
PDMS after imprinted gauze pattern