Hi Yanying,

HMDS (hexamethyldisilazane) treatment makes a Si-wafer's surface hydrophobic
and can be easily removed with a standard alkaline developer. Thus, the
following recipe will lead to the desired pattern of hydrophilic and
hydrophobic areas:
- HMDS treatment of the Si wafer
- resist coating (e.g. AZ 1512) and patterning by optical lithography
- resist develop with a standard alkaline developer (e.g. AZ 400K)
- resist removal with solvent (e.g. acetone)

This is exactly what Marty did when he stripped his exposed wafer (see
#154).

Frank

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> Message: 3
> Date: Sun, 13 Jan 2002 20:37:10 +0800
> From: Yanying Feng 
> To: memsGROUP 
> Organization: Tsinghua University
> Subject: [mems-talk] If there is any method to make some domains
> hydrophobic and the
>  others hydrophilic in microchannels?
> Reply-To: [email protected]
>
> Dear Lady or Gentlmen:
>      I want to form some surface pattern of hydrophility in
> microchannels.Is there any method to make some domains hydrophobic and the
> other hydrophilic in silicon microchannels? The microchannel is
> constructed by bonding a silicon substrate with etched channels to a Pyrex
> glass coverslip. Thank you any way!
>
>
> With best regards
>
>             Yanying Feng
>             [email protected]
> ________________________________________________________
> MEMS Lab
> Department of Precision Instruments and Mechanology
> Tsinghua University
> Beijing
> P. R. China
> 100084
> _________________________________________________________