Design and fabrication of si-based photonic crystal stamps

Abstract

In this work we report on the technology for enabling the mass replication of custom-designed and e-beam lithographically prepared structures via establishing UV-NIL nanoimprint processes for pattern transfer into UV curable pre-polymers. The new nano-fabrication technology based on the concept of disposal master technology (DMT) is suitable for mass volume manufacturing of large area arrays of sub-wavelength photonic elements. To show the potential of the application of the new nanoimprint technologies we choose as an example the fabrication of a photonic crystal (PhC) structure with integrated light coupling devices for low loss interconnection between PhC light wave circuits and optical fiber systems. We present two kinds of PhCs for fabrication of nanoimprint lithography stamps in Si. (a) A photonic crystal of Si-rods in air. This structure was fabricated with electron beam lithography (EBL) in resist and after lift-off, there is a mask of Cr on Si, then the pattern transfer into Si is performed using reacting ion etching (RIE) with SF6 as etch gas. We use 260 nm of positive resist (950K PMMA) for EBL exposure. Resist thickness, exposure dose, development time and parameters for etching have been optimized in this method. (b) In the second method lift-off was performed and metal mask was used as master. The subsequent steps for fabricating the master will be presented detail in our contribution.