Patterning vertical sidewall for optical assembly

Abstract

Abstract. We report two approaches of the fabrication techniques for three-dimensional patterning across vertical sidewalls based on the photolithography. One approach applies the techniques of spray coating the photoresist and the angled exposure. The supposed application is the microenergy source summing the voltage of silicon (Si) photo cells. Since Si photo cell islands on the buried oxide are isolated from each other, the output voltage is summed well without interacting with the common substrate. Wiring using the vertical sidewalls minimizes the shadow region caused by the metal electrode. Another approach introduces a new sheet, which consists of polyvinyl alcohol (PVA) and polyethylene terephthalate layers. The photoresist film is spin-coated and pasted on the substrate making the bridge over the trench. The pattern of the cantilever overhanging the trench is transferred. Then, PVA is dissolved in water and the resist is developed. When the rinse water dries, the cantilever bends and adheres on the vertical sidewall. The minimum pattern width designed is 10  μm and is obtained on the vertical sidewall.