Design and Numerical Studies of Optical Alignment Rulers for Layer-by-Layer Integration

Plasmonics structures have gained great attention by research since these structures could be engineered to manipulate light into a unique fashion. They allow the coupling of the incident radiation with the surface electrons on the metal surface of the structure. This coupling has been utilized in a variety of applications including structural coloring, imaging, sensing, and security. In this research, a study of a potential alignment technique based on a plasmonic structure is proposed and designed by incorporating nano-optical technology for possible uses in vertical integration of device layers in 3D ICs technology to boost the performance while maintaining small form factor. The structures are positioned onto the layers that need to be integrated. TE (Transverse Electric) and TM (Transverse Magnetic) modes are used to achieve the accurate integration and alignment: light blocking mode only and light blocking with plasmonics mode. In the light blocking mode, incident light is s-polarized and is used to guide the horizontal alignment where light intensity changes are very sensitive to the small nano physical shifts. In the other mode, with consideration of surface plasmon excitation, incident light is p-polarized and is used to guide the complete alignment where light transmission peaks are observed. To validate these modes, numerical studies are carried using simulations and presented here.