Scanning electron micrographs, silicon-based

As a first step in our study, we decided to assess our idea of microfabricated nib tips with simple structures based on the negative photoresist SU-8. Structures having a 2/2 D topology were fabricated on a silicon wafer support 11 it should be noted that the nib feature is not completely planar as the tip of the nib tended to point upwards due to stress in the thick SU-8 polymer layer. The nib structure is composed of a reservoir feature, a capillary slot leading the liquid to the tip of the nib where electrospray occurs upon HV application. These first nib prototypes have a microfluidic capillary slot with a width of around 20 pm. Figure 5.2 shows a scanning electron micrograph of a microfabricated nib tip in SU-8 and supported on a silicon support. 

Figure 3.2. Scanning electron micrographs of mechanically polished rigid conducting composite electrodes based on (A) Araldite-M-graphite (73.2%3, [B) Araldite-CW2215-graphite (45.8%), (C) silicone-graphite (61,0%), (D) epoxy-H77-graphite (20.0%) (Adapted with permission from Analyst 2002, 127, 1512-1519. Copyright 2002, The Royal Society of Chemistry).

Fig. 20. Examples of silicon-containing polymers for use in bilayer resist formulations. The top structure is used in a 248-rnn bilayer CA resist. The scanning electron micrograph shows the high aspect ratio images that can be obtained using 248-mn projection lithc a-phy with a bilayer resist based on this polymer. The bottom structure shows an example of a silicon-containing polymer designed for use in 193-nm lithography.

---