Photopatterning

E. Bacher, S. Jungermann, M. Rojahn, Y. Wiederhirn, and O. Nuyken, Photopatterning of crosslinkable hole-conducting materials for application in organic light-emitting devices, Macro-mol. Rapid Commn., 25 1191-1196 (2004). 

Fig. 14 AFM images showing photopatterned lines of nanoporous materials. A is for a film thickness of 39 nm and B is for a film thickness of 127 nm. Reproduced from [52]...

Figure 19. Process steps for patterning polyimides by wet etching and dry etching and for direct photopatterning of a photosensitive polyimide. The abbreviation PR stands for photoresist.

With PSPIs, the photopatterning process involves significantly fewer process steps (Figure 19) and eliminates the need for expensive plasma equipment. However, the process is currently limited to aspect ratios of about 0.5 for negative features such as via holes. Higher aspect ratios can be obtained for positive features such as lines unfortunately, holes are the more-prevalent features for TFML structures. 

The electropolymerization of the semipermeable membrane can be performed on the Pt electrodes on a wafer as well as the photopatterning of the enzyme mem-... 

Song, S., Singh, A.K., Shepodd, T.J., Kirby, B.J., Microchip dialysis of proteins using in situ photopatterned nanoporous polymer membranes. Anal. Chem. 2004, 76, 2367-2373. 

Murine 3T3 fibroblasts, primary rat hepatocytes Photopatterning of PEG-DA film containing a photoinitiator 2003 [106]... 

Figure 18 UV photopatterning method. The molecular structure of a photocleavable SAM formed on glass surfaces. UV irradiation through masks placed on top of SAM-modified microchannels leads to the production of hydrophilic carboxylate groups in the irradiated regions (Zhao et al, 2001).

Use of more complicated functionality on the solubilized pentacene (6, 7) yields materials that can be photopatterned to give devices with mobilities ranging from 0.02-0.2 cm2 V-1 s-1 [20, 21]. A very recent addition to the category of pentacene molecules functionalized with removable solubilizing groups is diketone 8 [22], which is relatively soluble and can be converted back to pentacene (and carbon monoxide) by irradiation with ultraviolet light. 

Fig. 16 A Optical micrograph of two-dimensional photopattern generated by photolysis of a metallized hb-PY (81) through a copper-negative mask. B Image with a higher magnification and C molecular structure of polymer complex 81...

The photopatterning apparatus used is the same as shown in Fig. 12 [45, 51]. First, a photomask was set on a SAM sample in the vacuum chamber. Second, a quartz plate (thickness 10 mm) was put on the photomask, the chamber was evacuated to 10 Pa and the VUV light irradiated the sample for 20 min. The photomask consisted of quartz glass of 2 mm thick (transmittance at 172 nm 93%) with rectangular patterns of chromium as shown in Fig. 15(a). By using these patterns, the micropatterns were formed on the SAM sample by removing part of the SAM by the VUV irradiation as shown in Fig. 15(b). 

Photoelectrochemical etching The dissolution of a semiconductor in an electrolytic solution upon exposure to Ught. Used in the photopatterning of semiconductor surfaces. 

Fuhrmann, T., and Tsutsui, T. Synthesis and properties of a hole-conducting, photopattern-able molecular glass. Ghent, of Materials 1999, 11, pp. 2226-2232. 

Figure 4. Photopattern process for wafer stage applied UV curable silicone coating.

Fig. 9.26 AFM images of photopatterned crosslinked hole-transport layers Left illuminated through a mesh-1500 TEM grid, yielding squared features of 8 pm size separated by channels 5.6 pm wide [57] (in addition scratches from placing the mask on the mate-...

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