Mask structure crossing

Hydrogels Hydrogels consist of a cross-linked polymer system or a meshlike structure that is flexible and can swell in the presence of water, producing a hydrophilic surface and masking the components below. The most widely used hydrogels consist of poly(hydroxyethyl methacrylate) (PHEMA), poly(ethylene glycol) (PEG), or poly(vinyl alcohol) (PVA) and tend to have reduced interaction with tissue.22 31 44 53 55... 

A field shielded pixel structure is used. The cross-section of the active-matrix stack is shown in Fig. 14.6. The first four layers, defining the TFT, are identical with the stack presented in Section 14.2. The rows of the display are processed on the first metal level whereas the columns are processed on the second metal level. In the field-shielded pixel design, the pixel electrode is defined in a third metal level of gold, resulting in a six-mask process. The pixel pad overlaps the storage capacitor, TFT, and column lines with a 6 pm thick polyvinylphenol layer acting as inter-layer dielectric. The optical aperture thereby increases to over 95%. The TFT channel length (L) and width (W) are 5 pm and 140 pm, respectively. 

In Fig. 3 we show the AFM image of the silicon substrate surface after selective removal of the large-area solid oxide mask from it and the cross section of this structure. 

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